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8 Effects on Animals Animals can be affected directly by oil and gas activi- ties or indirectly via alterations in habitat or food supplies. At sea, animals can be affected by noise, particularly sounds generated by seismic exploration, and by spills of oil and other contaminants. On land, animals can be affected by noise associated with seismic exploration, routine industrial activities, vehicle and aircraft traffic, and disturbance of dens. In addition, animals can be indirectly affected by changes in vegetation caused by industrial activities, con- taminant spills, withdrawal of water from lakes and streams, and by the availability of anthropogenic food sources. For obvious reasons, attention has been directed toward animal species such as whales, seals, fish, bears, caribou, and birds that have particular economic, esthetic, or cultural value. Most invertebrates and many smaller vertebrates have not been studied. A review of the fates and effects of oil in the sea (NRC 2003) details much recent information. POPULATION DYNAMICS Terrestrial animals are mobile as adults. They can move away from sources of disturbance or find new habitat. De- clining populations in areas where local extinction is a dan- ger can be replenished by the immigration of individuals from other areas. The movements of individual animals, however, make it difficult to assess the effects of industrial activities on the North Slope. Data are needed on the behav- ior of individual animals and on trends over larger areas than are required, for example, to assess effects of road dust on plants. Although many studies have examined the responses of various species on the North Slope to roads, ground and aerial traffic, gravel pads, pipelines, and impoundments, it is diffi- cult to assess the implications of the findings for the long-term population dynamics of those species. Rarely are data avail- able with which to compare the quality of the lost or disrupted habitats with that of remaining, undisturbed habitats. There 98 are only inadequate estimates of the total fraction of high- quality habitats affected by commercial activities. To guide its thinking about effects of industrial activi- ties on animals, the Committee on Cumulative Environmen- tal Effects of Oil and Gas Activities on Alaska's North Slope used basic principles and concepts of population ecology. One process of central importance is habitat selection (Cody 1985~. All animals select habitats for various activities (breeding, molting, hibernating) using clues associated with the suitability of habitats for those activities. Because indi- viduals that make good habitat choices reproduce more suc- cessfully than those that make poor choices, populations evolve so that individuals prefer to be in habitats that best serve their needs. Thus, individual animals select the regions containing the best, on average, available habitats (Rosenzweig 1981), and use poorer habitats only when bet- ter habitats are fully occupied or when the density of indi- viduals in the better habitats is high enough to lower ex- pected success below levels attainable in poorer habitats. At a landscape scale, animals travel to regions that maximize long-term productivity, although in a particular year, those regions might not be the best (Griffith et al. 2002~. Biologists can use habitat selection behavior as an indi- cator of habitat quality. For example, because some species of waterfowl travel long distances after completing repro- duction to molt in particular areas on the North Slope, we can assume that those are the best available molting areas and that their loss would force individuals to molt in less favorable places. Similarly, if caribou typically calve in spe- cific areas, we can assume that those are the best available calving areas. Although data might not be available about the likely suitability of other areas to which individuals might be displaced it is prudent to assume that alternative areas are less desirable than the ones currently used. When patterns of habitat occupancy are constrained by behavioral dominance or population density, a population is likely to have "source-sink population dynamics" (Hanski
EFFECTS ON ANIMALS and Gilpin 1997), which result when reproductive rates are higher than death rates in high-quality habitats. The better habitats are sources of emigrants that disperse into and oc- cupy poorer quality habitats (sink habitats), in which death rates exceed birth rates. Population densities can be quite high in sink habitats even though persistence of the species in those habitats depends on a regular supply of immigrants from source habitats. An important consequence of source-sink population dynamics is that a substantial proportion of the population of a species can be found in sink habitats. Without detailed de- mographic data, distinguishing between source and sink habitats can be difficult at best (Pulliam 1988~. Loss of source habitats could threaten the viability of a population even though most of the habitat occupied by the species in a region remains relatively intact. Thus, as activities and struc- tures associated with oil and gas development expand into the National Petroleum Reserve-Alaska and into the foot- hills of the Brooks Range, the result could be an unexpected decline of species even though total habitat loss might be modest. In predicting the effects of expanded activity on the North Slope, the committee attempted to identify those spe- cies and areas where source-sink population dynamics are likely to be operating and used the available information to evaluate the likelihood that source-sink dynamics would oc- cur. Although all receptors were considered from this point of view, source-sink dynamics is discussed only for those that appear to be affected by it. MARINE MAMMALS Although primary productivity is low in the freshwater and marine ecosystems of northern Alaska, it is enough to support many species of carnivorous vertebrates. The ma- rine mammal fauna off northern Alaska consists of three truly arctic species: ringed seal (Phoca hispida), bearded seal (Erignathus barbatusJ, and polar bear (Ursus maritimus); and four subarctic species: spotted seal (Phoca largha), wal- rus (Odobenus rosmarus), beluga whale (Delphinapterus Lucas), and bowhead whale (Balaena mysticetus) that move into the area seasonally from the Bering and Chukchi seas (Ferrero et al. 2000, Frost and Lowry 1984, Lentfer 1988~. Beluga whales spend most of their time in the Beaufort Sea in deep offshore waters. Bowheacl Whales The bowhead whale is a large up to 18 m (60 ft) long- baleen whale that once was common in northern circumpo- lar waters. Massive exploitation by commercial whalers greatly reduced its numbers to the current five small groups in the Bering Sea, Okhotsk Sea, Spitzbergen, Davis Strait, and the Hudson Bay (Shelden and Rugh 1995~. The Bering Sea stock is found seasonally in the Bering, Chukchi, and Beaufort seas and in parts of the East Siberian 99 Sea. For many centuries bowhead whales have been impor- tant nutritionally and culturally to the coastal Native people of western and northern Alaska (Inupiat), the Chukotka Pen- insula (Inupiat and Chukchi) of the Russian Far East, and northwestern Canada (Inuit) (for example, see Krupnik 1987, Sheehan 1995, Stoker and Krupnik 1993~. This stock was heavily exploited by commercial whalers beginning in 1848 and ending in about 1914 (Woodby and Botkin 1993~. Be- fore commercial whaling, the population is estimated to have been between 14,000 and 26,000 (Breiwick et al.1981) with estimates of 22,000 animals having been taken (Shelden and Rugh 1995~. By the end of the commercial whaling period it is thought that only a few thousand remained. As a result of the 1993 census effort conducted off Point Barrow, Alaska, the Bering Strait stock of bowhead whales is estimated at 8,200 (95% estimation interval from 7,200 to 9,400) (Raftery and Zeh 1998~. The estimated annual rate of increase from 1978 to 1993 was 3.2% with 95% confidence interval 1.4% to 5.1%. As described in Chapter 1, accurate censuses of bowhead whales were accepted only after long efforts by Alaska Native hunters to correct earlier work. The Bering Sea stock of bowhead whales spends the winter (from about late November to about mid-March) in the Bering Sea primarily at or near the ice edge. In the spring, most bowheads move north from the vicinity of Saint Lawrence Island, along the Alaskan coast to Point Barrow, and then eastward, with most reaching the Canadian part of the Beaufort Sea by early to mid-June (Shelden and Rugh 1995~. Although many spring migrants move in newly form- ing open areas (leads) in the ice, bowheads also move through ice-covered seas (Clark and Ellison 1988, 1989; Clark et al. 1996), often breaking through ice (to at least 15 cm [6 in.~) to breathe (George et al. 1989~. Most spend the summer in the Canadian part of the Beaufort Sea. During fall (late August to mid-October), they migrate westward through the Alaskan part of the Beaufort Sea, then into the northern part of the Chukchi Sea, and then south along the Chukotka coast. Most return to the Bering Sea by mid- November. Bowhead whales feed primarily on euphausiids and copepods about 3-4 cm (Carroll et al. 1987, Lowry 1993, Lowry and Burns 1980, Lowry and Frost 1984, Lowry et al. 2001~. Bowheads feed throughout the year, at least to some extent. There are inadequate data to properly evaluate the importance of the Alaskan portion of the Beaufort Sea as feeding habitat for bowhead whales, especially during their fall migration. Because this is the time when they are sus- ceptible to disturbance by the noise of exploration for oil, the information is needed for a full assessment of the effects of noise on bowheads. It probably takes about two decades for a bowhead to achieve sexual maturity. Conception likely occurs in late winter or early spring, and calves are usually born during the spring migration (Kenney et al. 1981; Koski et al. 1993; Rugh et al. 1992; Shelden and Rugh 1995; Tarpley et al.
100 1983,1999; Tarpley and Hillmann 1999~. Bowheads can live 100 years or more (George et al. 1995, 1999~. Oil- and Gas-Relatecl Activities and Bowheacl Whales The activities most likely to affect bowhead whales are marine seismic exploration, exploratory drilling, ship and air- craft traffic, discharges into the water, dredging and island con- struction, and production drilling. To date there have been docu- mented effects of industrial noise. As was true of early censuses, the current understanding of the effects of noise on bowheads was achieved only after long efforts of Alaska Native hunters to correct early, imperfect studies (Chapter 1~. There have been no major offshore oil spills on the North Slope. Marine seismic exploration produces the loudest indus- trial noise in the bowhead whale habitat. Some seismic sur- veys are conducted in winter and spring on the sea ice, but most are done in the summer-autumn open-water period. Thus, bowheads and seismic boats are in the same areas dur- ing the westward fall migration. In the nearshore Alaskan Beaufort Sea, nearly all the fall-migrating bowhead whales avoided an area within 20 km (12 mi) of an operating vessel, and deflection of the whales began at up to 35 km (21 mi) from the vessel (Richardson 1997,1998,1999; NMFS 2002~. Noise levels received by these whales at 20 km (12 mi) were 117-135 dB (NMFS 2002~. Disturbance to fall migrating bowhead whales also has been shown in relation to offshore drilling in the Alaskan Beaufort Sea. At the 1992 Kuvlum site the approaching fall- migrating whales began to deflect to the north at a distance of 32 km (19 mi) east of the drilling platform and bowhead calling rates peaked at about the same distance (Brewer et al. 1993~. At the 1993 Kuvlum #3 site the whales were nearly excluded from an area within 20 km (12 mi) of the drilling platform (Davies 1997, Hall et al. 1994~. During the 1986 open-water drilling operations at the Hammerhead site, no whales were detected closer than 9.5 km (6 mi) from the drillship, few were seen closer than 15 km (9 ml), and one whale was observed for 6.8 hours as it swam in an arc of about 25 km (15 mi) around the drillship (LGL and Greeneridge 1987~. The zone of avoidance there- fore seemed to extend 15-25 km (9-15 mi) from the drillship. Acoustic studies done at the same time provided received levels of drillship noise that can be related to the zone of avoidance. At 15 km (9 mi) from the 1986 Corona site, received sound was generally 105-125 dB (LGL and Greeneridge 1987~; at 11 km (6 mi) from Hammerhead, re- ceived sound was generally 105-130 dB. Estimating Future Accumulation of Effects In~lustrial Noise If oil- and gas-related activities continue in the Alaskan waters of the Beaufort Sea, the major noise will be generated CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS by marine seismic exploration. Other significant noise will continue to be produced by exploratory and production drill- ing, island construction, and vessel transit. The probable con- sequences are diversion of animals from their normal migra- tory path, possibly into areas of increased ice cover, and less use of the fall migration corridor as feeding habitat. If two or more types of disturbance occur at the same time or in the same general area, the effects could be greater than those observed from single sources. The greatest diver- sion would occur if two or more seismic vessels operated simultaneously with one just offshore of the other. Such a disturbing influence set across the migratory path could displace the whales seaward into areas where ice con- ditions are more dangerous for hunters, prevent some whales from passing, reduce use of the area as feeding habitat, and affect the other behavior in the animals. Spille~l Oil There are no data on Arctic oil spills and bowheads be- cause no major oil spill has occurred in the Beaufort Sea. However, the potential for an oil spill and its likely effects on bowhead whales are viewed by bowhead-dependent hunt- ers as the greatest threat to the whale population and to their cultural relationship with the animal (Ahmaogak 1985,1986, 1989; Albert 1990~. Oil spilled in broken-ice cannot be cleaned up effectively, and it is expected that whales would not avoid oil-fouled waters. Each environmental impact statement (EIS) relating to industrial activity in the Beaufort Sea contains estimates of the likelihood of an oil spill. For example, the final EIS for Beaufort Sea Planning Area Oil and Gas Lease Sale 170 (MMS 1998: IV-A-12) estimated a 46-70% chance of a spill of 1,000 barrels (bbl) or more. Increasing industrial activity in the Beaufort Sea, coupled with existing production at the Endicott and Northstar facilities, would lead to rising prob- ability of a significant oil spill. The Exxon Valdez experience shows that cleaning up spilled oil is difficult, even in ideal conditions in ice-free waters (Loughlin 1994~. An oil spill would be most difficult to control during periods of broken ice in the fall when bowheads migrate through the area. During this period, new ice is forming, slush ice is often present, ice is in the form of chunks and pans, and ice formed earlier can move into the area with the drifting and shifting ice pack. Mechanical re- covery alone would likely be able to clean up only a small fraction of oil in broken ice (ADEC 2000~. An oil spill would pose less risk to bowhead whales if the whales could detect spilled oil and avoid it. Although there is no direct evidence about how bowhead whales would react to oil-fouled waters, Dall's porpoise, harbor porpoise, killer whales, and grey whales moved through waters con- taminated by the Exxon Valdez accident (Harvey and Dahlheim 1994~. Also, fin, humpback, and probably right whales did not avoid an oil spill off Cape Cod, Massachu-
EFFECTS ON ANIMALS setts (Goodale 1981, cited in BLM 1982~. Bowhead whales regularly surface in slush ice, and easily break through thin ice to breathe, so they are unlikely to avoid surfacing in oil- covered waters. The toxic effects of inhaled oil vapors and ingested oil on bowhead whales would probably be similar to those described below for seals and polar bears. A modest amount of attention has been devoted to study- ing the likely effects of spilled oil on bowheads (for example, see Albert 1981b, Hansen 1985 and Beaufort-Sea-related EISs). One method compares the structure of the various tissues of the whale that are most likely to contact the oil with those of better-studied mammals. Related studies of the bowhead, begun in the late 1970s with examination of sub- sistence harvested whales and with the collection and ex- amination of tissues from those whales (Albert 1981a, Kelley and Laursen 1980), indicated that the skin, the eyes, the ba- leen, and the lining of the gastrointestinal tract of bowhead whales are likely to be injured by contact with spilled oil (Albert 1981b). 101 The Skin The skin of a bowhead whale is 10-22 mm (0.4-0.9 in.) thick over much of its body (Haldiman et al. 1981, 1985, 1986~. Although bowheads have the soft, smooth skin typi- cal of most cetaceans, they also have dozens to hundreds of roughened areas (1-4 cm [0.4-1.6 in.] diameter) of skin sur- face (Albert 1981b, Haldiman et al. 1985, Henk and Mullan 1996) the cause of which is not yet known (see Figure 8-1~. In some of the roughened areas, the epidermal cells between the epidermal rods have been removed. The exposed epider- mal rods then appear as tiny hairlike or filamentous projec- tions. The great increase in exposed surface (microrelief) of these roughened areas increases the area to which oil can adhere. In a laboratory experiment, oil adhered, in propor- tion to the roughness of the skin surface, to formalin-pre- served bowhead skin exposed to crude oil on water (Haldi- man et al. 1981~. The roughened areas of skin had large numbers of diatoms and bacteria, including potential patho- FIGURE 8-1 Subsistence harvested bowhead whale, on the ice at Barrow. This photo shows a portion of the left side of the head. The blowhole area is in contact with ice (near knife). A portion of left row of baleen is visible in the upper right of the photo. Note the large number of lesions (arrows) on the skin surface. These commonly seen eroded areas make the skin surface much rougher than in unaffected areas. A section of skin with lesions (upper right) was removed from the skin of the upper jaw. Photograph by Thomas Albert.
102 yens with varying tissue-destructive enzymes (Shotts et al. 1990~. Thus, it is likely that oil contact would be harmful. The Eyes The conjunctival sac associated with the eye is so exten- sive that an adult human's fingers can pass beneath the eye- lids and reach approximately two-thirds of the way around the eye (Albert 1981b, Dubielzig and Aguirre 1981, Haldi- man et al. 1986~. Thus, a large surface exists for an irritant (such as spilled oil) to contact sensitive visual structures (Zhu 1996, 1998; Zhu et al. 2000, 2001~. The Baleen Bowheads filter prey from the water with their exten- sive baleen apparatus (Lambertsen et al. 1989~. Many of the hair-like filaments that form the margin of the baleen plates break off during feeding and are commonly found in the stomachs of harvested bowheads. Because the bowhead's baleen apparatus is so extensive and the filaments on the margin of each plate are so prominent, the baleen would be fouled if a whale fed in oiled waters (Albert 1981b, Braith- waite 1980, Braithwaite et al. 1983~. A laboratory study (Braithwaite et al.1983) showed that Finclin s crude oil strongly adhered to isolated bowhead baleen and 9 interfered with filtration efficiency for approximately 30 days. Less of an effect on filtration was found on isolated baleen of species (fin, set, humpback, gray whale) that have shorter, stiffer bristles than bowheads (Geraci 1990, Geraci Baleen attached to jaw of subsistence-harvested bowhead whale. September 2001. Photograph by David Policansky. CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS and St. Aubin 1982, 1985~. Petroleum also had little direct effect on isolated baleen from several whale species (St. Aubin et al. 1984~. A bowhead probably could filter out the heavier portions of spilled oil, including globules and "tar balls," and would probably swallow the oily material and the dislodged oiled baleen filaments along with its prey. The Stomach Broken-off baleen bristles swallowed during feeding can form "tangles" in the stomachs of bowheads (George et al. 1988~. Those dislodged bristles could combine in the stom- ach with weathered oil components (such as tar balls) to form a sticky mass (Albert 1981b). The stomach of the bowhead whale consists of four chambers, one of which is a narrow channel that connects two other larger chambers (Tarpley 1985; Tarpley et al. 1983, 1987~. Blockage, leading to gastric obstruction, could occur in this small, narrow connecting channel, which has small entrance and exit openings, if a bowhead fed in oil- fouled waters (Albert 1981b). Ingested oil would also have toxic effects whose severity would be related to the amount of oil swallowed. · Noise from exploratory drilling and marine seis- mic exploration causes fall-migrating bowhead whales to divert around noise sources, including drillship operations and operating seismic vessels, at distances of 15-20 km (9-12 ml). · In view of the large zone of near total avoidance around a single operating seismic vessel, if more than one such vessel is operating in the Alaskan portion of the Beau- fort Sea when fall-migrating bowheads are in those waters, the diversion of migrating whales could be much greater. · Data needed for an improved assessment of the ef- fects of seismic noise was delayed for many years due to overreliance on a study that underestimated such effects, and because of inadequate consideration given to relevant obser- vations by subsistence hunters. · Available data are inadequate regarding the full ef- fects of industrial noise (seismic noise in particular) on fall- migrating bowhead whales in the Alaskan portion of the Beaufort Sea. · There are inadequate data regarding the importance of the Alaskan portion of the Beaufort Sea as feeding habitat for the bowhead whale, especially during the fall migration. · Harm to marine mammals from contact with spilled oil (as in the Exxon Valdez experience and other instances) and specific morphological characteristics of the bowhead whale (extensive baleen apparatus, eroded areas of skin, ex- tent of conjunctival sac, narrowness of stomach-connecting channel) indicate that spilled oil would pose a great potential threat to those organs in bowhead whales.
EFFECTS ON ANIMALS Recommenclations · Studies should determine the distance from an oper- ating seismic vessel (and received noise at that distance) at which the "average" bowhead whale begins to deflect, be- gins to change its rate or type of vocalization, reaches the point of greatest deflection, and returns to the normal migra- tion path. Studies also should examine the effects of mul- tiple noise sources in different configurations. · Studies should determine the extent to which bow- head whales make use of the Alaskan portion of the Beaufort Sea as feeding habitat. · The use of sound to divert whales from a spill site and prevent them from contacting spilled oil should be investigated. Seals and Polar Bears In Alaska, spotted seals, bearded seals, and walrus spend most of their time in the Bering and Chukchi seas and gener- ally use only the westernmost part of the waters off the Alaska North Slope. Ringed seals and polar bears are com- mon in waters off the North Slope where oil and gas explo- ration and development have occurred. The main areas of concern with regard to effects on those animals from oil and gas activities are the potential for contamination (reviewed by Geraci and St. Aubin 1990) and for disturbance caused by industrial noise in the air and water (reviewed by Richardson et al. 1995). The effects of industrial activity on marine mammals in the North Slope have been difficult to measure. Clearly, spilled oil can be toxic to marine mammals (Geraci and St. Aubin 1990, Loughlin 1994, NRC 2003), although there have been no major spills in the Beaufort Sea, or in any similar arctic environment, so no field data exist that can be used to evaluate or predict consequences. Observations and studies of responses of marine mammals to noise are diffi- cult to interpret (Richardson et al. 1995~; nevertheless, it is clear that noise can cause pronounced behavioral reactions and displacement of some species. However, it has not been possible to predict the type and magnitude of responses to the variety of disturbances caused by oil and gas operations, or, most important, to evaluate the potential effects on popu- lations. Even if there were no effects on populations of the affected marine mammal species, displacement of animals could have important consequences for Alaska Natives seek- ing to harvest those animals for subsistence. Hunting and Other Deaths Causecl by Humans Before the Marine Mammal Protection Act (MMPA) became law in 1972, active sport hunting for polar bears off western and northern Alaska reduced that population (Amstrup et al. 1986~. Since then, marine mammals may be hunted only for subsistence and handicraft purposes by Alaska Natives, and there are no federally imposed limits on 103 that hunting unless populations are declared depleted. Since 1988, hunting of polar bears from the southern Beaufort Sea stock has been controlled by a conservation agreement be- tween the Inupiat of northern Alaska and Inuvialuit of the western Canadian Arctic who hunt a shared population (Nageak et al. l991~; the number of animals taken each year is well documented. From 1988 to 1995 the average annual take of 58.8 bears was well below the estimated "potential biological removal level" of 73 (FWS 1998) and therefore was considered safe. Little is known about the number of ringed seals har- vested, but they are an important subsistence resource to in- digenous people throughout the Arctic (Smith et al. 1991~. Alaska Native dependence on, and interest in, hunting ma- rine mammals is influenced by many factors, including cul- tural involvement, employment, community wealth, logis- tics, and ice and weather conditions. The number of animals killed by hunters can be expected to vary accordingly. How- ever, current legal restrictions should prevent harm to popu- lations of these animals if they are properly enforced. Marine mammals also are killed in other ways. At least one ringed seal pup has been killed by a bulldozer that was clearing seismic lines on shore-fast ice of the Beaufort Sea. A polar bear died on the North Slope apparently after eating a container of dye used to mark temporary airstrips (Amstrup et al. 1989~. It is not uncommon for residents to shoot polar bears in defense of life and property, both in coastal commu- nities and at industrial facilities. Two polar bears were killed in this manner along the Beaufort Sea coast in 1990 and 1993, one at the Stinson oil exploration site and the other at Oliktok Point (S. Schliebe, FWS, personal communication, 2001~. Regulatory agencies and the oil and gas industry have made serious efforts to minimize interactions with polar bears, both to increase human safety and to safeguard the bears (Truest 1993~. Oil Laboratory experiments in which three polar bears were coated with crude oil showed dramatic effects (0ristland et al. 1981~. Oil ingested during grooming caused liver and kidney damage. One bear died 26 days after oiling and another was euthanized. Stirling (1990) detailed numerous behavioral char- acteristics and ecological considerations that suggest that po- lar bears are especially susceptible to oil contamination. Labo- ratory experiments also have been done to determine the effects of oiling on ringed seals (Englehardt et al.1977~. After 24 hr in a pen with oil-covered water, ringed seals' blood and tissues showed evidence of hydrocarbons that had been incor- porated through inhalation, and kidney and liver damage. In another study (Geraci and Smith 1976), three seals died within 71 minutes after oil was put into their pool, presumably be- cause of a combination of hydrocarbon inhalation and stress. Data presented by St. Aubin (199Oa) described the various ways that pinnipeds could be affected by oil, much of it con-
104 firmed by studies of effects of the Exxon Valdez oil spill on harbor seals (Frost et al. 1994a,b; Lowry et al. 1994; NRC 2003; Spraker et al. 1994~. However, as far as is known, nei- ther ringed seals nor polar bears have been affected by oil spilled as a result of North Slope industrial activities. Noise Most of the effort to describe the effects of noise and disturbance on marine mammals has been devoted to studies of bowhead whales. However, pinnipeds also react to a vari- ety of disturbances, such as noise from aircraft and ocean vessels (Richardson et al. 1995~. Some studies of the poten- tial effects of disturbance on shore-fast ice on pupping ringed seals have been done. Those studies showed that there was probably some displacement of ringed seals from areas close to artificial islands in the central Beaufort Sea (Frost and Lowry 1988), and that there was a higher abandonment rate of seal breathing holes close to seismic survey lines (Kelly et al. 1988~. Noise probably affects haulout behavior of pinni- peds but no quantitative data are available. From data col- lected in the central Beaufort Sea from 1985 to 1987, Frost and colleagues (1988) concluded that there were no broad- scale effects of industrial activity on ringed seals that could be measured by aerial surveys, but they also noted that there was little offshore activity during those years. Subsequent industry-funded monitoring studies for the Northstar and Liberty projects suggested minor effects on ringed seals from ice road construction and seismic exploration (Harris et al. 2001, Richardson and Williams 2000~. For most of the year, polar bears are not very sensitive to noise or other human disturbances (Amstrup 1993, Richardson et al. 1995~. How- ever, pregnant females and those with newborn cubs in ma- ternity dens both on land and on sea ice are sensitive to noise and vehicular traffic (Amstrup and Gardner 1994~. Seismic exploration has disturbed a bear in a maternity den (FWS 1986~. Current regulations require industry to avoid polar bear dens as much as possible (FWS 1995b). Habitat Changes Human activities in, on, and adjacent to sea ice can cause habitat changes that affect marine mammals. In winter, ringed seals maintain holes in the shore-fast ice, and they give birth to their pups in lairs under the snow in spring (Smith and Stirling 1975~. If the thickness of the ice, the amount and distribution of snow cover, or the timing and characteristics of breakup change, seal productivity or sur- vival will be reduced (Furgal et al.1996, Smith and Harwood 2001~. Polar bears can be attracted to artificial structures that create leads in the ice because the leads increase the area bears use to hunt ringed seals. Buildings also offer places for bears to forage for human discards and stimulate their curi- osity (Stirling 1988a). Not only does this increase the likeli- hood that bears will encounter contaminants, but it also in- CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS creases the chances they will need to be driven away or killed to protect human safety. Ice breaking, especially in areas of shore-fast ice, obviously would result in major changes to habitat, with likely effects on ringed seals and polar bears. In waters off the North Slope, ringed seals feed princi- pally on arctic cod, euphausiids, and amphipods (Lowry et al. 1980~. Those species, along with bowhead whales, copepods, and seabirds, form a relatively simple pelagic trophic system with some obvious potential for competitive interactions (Frost and Lowry 1984~. Ringed seals are the primary prey of polar bears (Smith 1980, Stirling 1988b). Changes in popula- tion sizes of any of these species, either natural or caused by humans, could affect other components of the ecosystem. For polar bears, mark-recapture studies in the Beaufort Sea suggest that the population increased considerably be- tween 1967 and 1998 (Amstrup et al. 2001), probably be- cause hunting has been limited (Amstrup et al.1986~. Ringed seals are harder to count. Efforts to develop a program to monitor ringed seals in the Beaufort Sea region began in 1985-1987 and continued in 1996-1999. Analysis of data from 1970 to 1987 (Frost et al. 1988) suggested the density of hauled-out seals fluctuated considerably from a high of 3.5 seals per km2 (9.1 seals per mi2) to a low of 1.1 seals per km2 (2.6 seals per mid. Results of more recent surveys are being analyzed (Frost et al. 2002~. Neither assessment pro- gram is sensitive enough to detect the substantial changes in population size that would be expected to result from oil and gas exploration and development and other human activi- ties. However, because so far the marine waters of the Beau- fort Sea have seen only limited and sporadic industrial activ- ity, it is likely that there have been no serious effects or accumulation of effects on ringed seals or polar bears. Permitting Inciclental Take The Marine Mammal Protection Act prohibits the tak- ing of marine mammals including polar bears and ringed seals except in specifically permitted circumstances. The MMPA allows the secretary of commerce to permit indus- trial operations (including oil and gas exploration and devel- opment) to take small numbers of marine mammals, pro- vided that doing so has a negligible effect on the species and will not reduce the availability of the species for subsistence use by Alaska Natives. Regulations governing the permits identify permissible methods, means to minimize harm, and requirements for monitoring and reporting. The permits have been used to minimize the effects of on-ice activities on pup- ping ringed seals, to require planning and personnel training that minimizes conflicts with polar bears, and to provide buffer zones around known polar bear maternal den sites. Potential for Accumulation of Effects Although the U.S. Fish and Wildlife Service (FWS) has produced a useful review of current and future threats to
EFFECTS ON ANIMALS polar bears and their habitats (FWS 1995b), no formal pro- jections have been made of how likely effects on ringed seals or polar bears from future oil and gas activities are to accu- mulate with effects of other human activities. For purposes of making such a projection, the committee's scenario as- sumes that offshore exploration for oil and gas, and possible extraction, will occur in the Beaufort Sea from Barrow to Flaxman Island, and possibly to the Canadian border. Activ- ity would occur mostly near shore, adjacent to onshore oil reserves, and development would entail methods and struc- tures similar to those currently in use (gravel islands or bottom-founded structures, horizontal drilling, buried pipe- lines, and an emphasis on working during winter). Full-scale industrialization of near-shore areas would most likely result in at least partial displacement of ringed seals. The frequency with which polar bears come into con- tact with people and structures is undoubtedly a function of the amount of activity in their habitats. Even with the best possible mitigation measures in place, it is certain that some bears will be harassed or killed. More human activity along the coast and near shore could reduce the suitability of some areas for use by donning female bears. This effect is likely to be greatest east of the Canning River, especially within the 1002 Area of the Arctic National Wildlife Refuge, where the highest concentration of on-land dens is found (Amstrup 1993, Amstrup and Gardner 1994~. Efforts to identify areas where polar bears are most likely to den in the eastern part of the North Slope (Durner et al. 2001), should improve the ability of regulators and industry to reduce disturbance of donned bears. Contact with spilled oil or other contaminants in the ocean would harm ringed seals and polar bears, and the like- lihood of spills would increase with increased exploration and development. Amstrup and colleagues (2000) modeled the spread of a hypothetical 5,900 bbl (939,000 L, 248,000 gal) oil spill from the Liberty prospect) as it might affect the seasonal distribution and abundance of polar bears in the Beaufort Sea. The number of bears potentially affected by such a spill ranged from O to 25 with summer open-water conditions and O to 61 with autumn broken-ice conditions. In its findings permitting the oil and gas industry to take polar bears in Alaska waters, the FWS stated, "We conclude that if an oil spill were to occur during the fall or spring broken-ice periods, a significant impact to polar bears could occur" (65 Federal Register 16833 [20001~. It seems likely that an oil spill would affect ringed seals the same way the Exxon Valdez affected harbor seals (Phoca vitulina) (Frost et al. 1994a, Lowry et al.1994, Spraker et al.1994), and the number of animals killed would depend largely on the sea- son and the size of the spill. Polar bears could be further affected if they ate oil-contaminated seals (St. Aubin l990b). Climate change also will affect marine mammals (Tynan and DeMaster 1997~. Sea ice is important in the life of all ~ The Liberty prospect is not being developed as of late 2002. 105 marine mammals in the arctic and subarctic regions (Fay 1974~. Already, there have been dramatic decreases in the extent and thickness of sea ice throughout the northern hemi- sphere, and those trends are expected to continue through the next century (Vinnikov et al. 1999, Weller 2000~. The distribution, abundance, and productivity of Alaskan marine mammal populations will likely be altered by the combined effects of changes in physical habitats, prey populations, and interspecies interactions (Lowry 2000~. Warming is likely to increase the occurrence and residence times of subarctic spe- cies (spotted seals, walrus, beluga whales, bowhead whales) in the region. Negative effects on populations of truly arctic species (polar bears, ringed seals, and bearded seals) are likely to result from climate warming. Polar bears and ringed seals depend on sea ice, and reductions in the extent and persis- tence of ice in the Beaufort Sea will almost certainly have negative effects on their populations (FWS 1995b). Climate change has already affected polar bears in western Hudson Bay, where bears hunt ringed seals on the sea ice from No- vember to July and spend the open-water season on shore where they feed little. In a long-term study, Stirling and col- leagues (1999) documented decreased body condition and reproductive performance in bears that correlated with a trend toward earlier breakup of sea ice in recent years. The earlier breakup gives bears a shorter feeding season. They are leaner when they come ashore, and they must fast longer. Many ringed seals give birth to and care for their pups on stable shore-fast ice, and changes in the extent and stability or the timing of breakup of the ice could reduce productivity (Smith and Harwood 2001~. Because of the close predator- prey relationship between polar bears and ringed seals, de- creases in ringed seal abundance can be expected to cause declines in polar bear populations (Stirling and 0ritsland 1995~. How these independent factors might combine to influ- ence populations cannot be predicted with current knowl- edge. If climate warming and substantial oil spills did not occur, cumulative effects on ringed seals and polar bears in the next 25 years would likely be minor and not accumulate. Currently there are no research plans or studies that spe- cifically address potential accumulating effects on polar bears or ringed seals off the North Slope. Unless such stud- ies are designed, funded, and conducted over long periods (decades), it will be impossible to verify whether the effects occur, to measure their magnitude, or to explain their causes. Finclings · Industrial activity in marine waters of the Beaufort Sea has been limited and sporadic and likely has not caused serious accumulating effects on ringed seals or polar bears. · Careful mitigation can help to reduce the effects of North Slope oil and gas development and their accumula- tion, especially if there is no major oil spill. However, the
106 effects of full-scale industrial development of the waters off the North Slope would accumulate through displacement of polar bears and ringed seals from their habitats, increased mortality, and decreased reproductive success. · A major Beaufort Sea oil spill would have major ef- fects on polar bears and ringed seals. · Climate warming at predicted rates in the Beaufort Sea region is likely to have serious consequences for ringed seals and polar bears, and those effects will accumulate with the effects of oil and gas activities in the region. · Unless studies to address potential accumulation of effects on North Slope polar bears or ringed seals are de- signed, funded, and conducted over long periods, it will be impossible to verify whether such effects occur, to measure them, or to explain their causes. CARIBOU Introduction The effects of North Slope industrial development on barren-ground caribou (Rangifer tarandus grant)) herds have been contentious. Although much research has been con- ducted on caribou in the region, researchers have disagreed over the interpretation and relative importance of some data and how serious data gaps are. The disagreements are espe- cially significant because caribou are nutritionally and cul- turally important to North Slope residents and because cari- bou are widely recognized as important symbols of the state and well-being of North Slope environments. For these rea- sons, the committee assembled information on caribou and evaluated conflicting interpretations of the information about how oil and gas development might have affected their popu- lation dynamics. The committee's consensus on effects to date, and projections of probable future effects, is the prod- uct of this careful analysis and deliberation. Assessing the effects of oil and gas development on cari- bou is not straightforward because many factors other than oil and gas activities affect the sizes of North Slope caribou herds weather, vegetation, disease, and predators, for ex- ample. Therefore, there is no steady baseline against which to identify and assess disturbance-induced changes. To evaluate the effects of petroleum development on caribou, the committee examined changes in distribution and habitat use, and evaluated the nutritional and reproductive implica- tions of those changes and how they altered population dynamics. Background Caribou are ubiquitous on the North Slope. Four sepa- rate herds, ranging nearly 20-fold in size, are recognized on the basis of distinctly different calving grounds (Skoog 1968, Figure 8-2~. The extent of seasonal migration varies with herd size (Bergerud 1979, Fancy et al. 1989, Skoog 1968~. CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS By far the largest is the Western Arctic Herd (WAH), esti- mated at 460,000 (in 2001~. It calves in the Utukok uplands south of Barrow and summers throughout the North Slope and Brooks Range west of the Colville River, including most of the National Petroleum Reserve-Alaska. Wintering areas include both the western North Slope and the southern foothills of the Brooks Range. The annual range of the Teshekpuk Lake Herd (TLH), numbering 27,000 (in 1999), lies within the WAH summer range. Calving and summer ranges are in the coastal zone near Teshekpuk Lake; the win- ter range typically is confined to the coastal plain and nearby foothills. Estimated at 123,000 (in 2001), the Porcupine Cari- bou Herd (PCH) calves on the coastal plain and lower uplands in northeastern Alaska within the Arctic National Wildlife Refuge and adjacent Yukon Territory. During the summer, the PCH ranges throughout much of the eastern North Slope and Brooks Range; its wintering areas include the Ogilvie and Richardson mountains in western Canada and the southern Brooks Range in eastern Alaska. At 27,000 (in 2000), the Central Arctic Herd (CAM) is distributed pri- marily within state lands between the Colville and Canning rivers. CAM calving and summer ranges are on the coastal plain, and the winter range typically extends southward into the northern foothills of the Brooks Range. During the past 27 years, the size of the PCH has been nearly constant; the other three herds have increased substantially (Figure 8-3~. Central Arctic Hercl For the past 50 or 60 years, all four herds (Figure 8-2) have been exposed to oil and gas exploration activity, but only the CAH has been in regular and direct contact with surface development related to oil production and transport. Its calving ground and summer range lie within the oil-field region near Prudhoe Bay; its autumn, winter, and spring ranges encompass the Dalton Highway (also called the Haul Road) and the area around the Trans-Alaska Pipeline (Cameron and Whitten 1979b). The CAH has increased from around 5,000 animals in the late 1970s to its current (2000) size of 27,000 (Figure 8-3~. Parturient females, along with most nonparturient fe- males and yearlings, arrive on the coastal calving ground in mid-May (Gavin 1978, Smith et al. 1994~. The exact timing depends on patterns of snowfall and snowmelt (Cameron et al. 1992, Gavin 1978~. Most calving occurs within 50 km (31 mi) of the Beaufort Sea (Whitten and Cameron 1985, Wolfe 2000~. Virtually all calves are born between late May and early June (Cameron et al. 1993) within two or three calving concentration areas (Whitten and Cameron 1985, Wolfe 2000~. At the landscape level, selection and repeated use of a calving ground is probably related to both the distri- bution of predators, which are less abundant on the coastal plain (Rausch 1953; Reynolds 1979; Shideler and Hechtel 2000; Stephenson 1979; Young et al. 1992, 2002) and the likelihood of favorable foraging conditions (Griffith et al.
EFFECTS ON ANIMALS 107 :~ . ~ ~ FIGURE 8-2 Arctic caribou herds. SOURCE: Alaska Geobotany Center, University of Alaska Fairbanks, 2002. 7 - .N 6 - cn Cad o 5 - . _ =4 - o AL 3 _ . _ ~ 2 - a~ - lY 1 - .~W fit it: - O- 1 1 1 1 1 1 1 1 1 1 1 1975 1980 1985 1990 1995 2000 Year - PCH - 1 78K WAH - 463K CAH - 27K m TLH - 28K FIGURE 8-3 Relative post-calving herd sizes (minimum ob- served = 1.0) of the four Alaska barren-ground caribou herds (PCH, Porcupine Caribou Herd; WAH, Western Arctic Herd; CAH, Cen- tral Arctic Herd; TLH, Teshekpuk Lake Herd), 1976-2001. Maxi- mum observed population size for each herd is noted in the legend. SOURCE: Griffith et al. 2002. 2002~. Annual shifts in concentrated calving within the over- all calving ground are driven by spatial changes in the qual- ity and quantity of new forage, principally sedges (Bishop and Cameron 1990, Wolfe 2000~. An additional advantage of coastal calving is proximity to "insect-relief habitat," which eliminates the need for extensive travel with a young calf. Bulls and the remaining noncalving females and sub- adults, which stay inland during the calving period, follow the northward progression of plant growth (Whitten and Cameron 1979), arriving on the coastal plain in late June (Cameron and Whitten 1979a, Gavin 1978~. The midsum- mer diet includes a variety of deciduous plants (Roby 1978; Trudell and White 1981; White and Trudell 1979, 1980; White et al. 1975, 1981~. Insects substantially affect energy balance by reducing food intake and by increasing energy expenditure. Mosqui- toes are present from late June through late July (Dau 1986, Russell 1976, White et al.1975~. On warm, calm days, when mosquitoes are active, caribou move rapidly to cooler, windier areas on or near the coast, returning inland to pre- ferred feeding areas when harassment abates (Cameron and Whitten 1979a, Cameron et al.1995, Child 1973, Dau 1986, Roby 1978, White et al. 1975~. These movements appear to optimize foraging opportunity relative to energy expendi- ture (Russell 1976, Russell et al. 1993, Walsh et al. 1992, White et al. 1975~. Oestrid flies (warbles and nose bots) emerge in mid-July and persist through early August (Dau 1986~. When oestrids are active, caribou stand head-down or run erratically (Dau 1986, Nixon 1990, Roby 1978~. This behavior probably reduces larval infestation, but at the ex- pense of energy balance (Helle and Tarvainen 1984, Murphy and Curatolo 1987, Russell et al. 1993~. By autumn, caribou move inland (Cameron and Whitten 1979a), and breeding occurs from late September through mid-October, while enroute to the winter range. Most of the
108 CAH winters in the foothills and mountainous terrain of the northern Brooks Range, although a few caribou typically remain on the coastal plain year round (Cameron and Whitten 1979b, Cameron et al. 1979, White et al. 1975~. Lichens, which are low in protein, predominate in the winter and spring diets (Roby 1978~. Ecological Strategies During June and July, caribou body energy and nutrient reserves are low (Chan-McLeod et al. 1999, Gerhart et al. 1996), and parturient and maternal females attempt to maxi- mize theirintake of high-quality forage (Klein 1970, Kuropat 1984, Kuropat and Bryant 1979, Russell et al. 1993, White et al.1975~. They replenish body protein reserves mobilized during late gestation (Gerhart et al. 1996) and attempt to meet or exceed the metabolic demands of lactation (White et al. 1975, 1981), which are highest during the first 3 weeks postpartum (Chan-McLeod et al. 1999, White and Luick 1984~. The benefits of good nutrition include increased growth rates (Allaye-Chan 1991, White 1992) and survival of calves (Haukioja and Salovaara 1978~. Good nutrition also enhances summer weight gain of a female and increases the probability that she will conceive in autumn (Adams and Dale 1998; Cameron and Ver Hoef 1994; Cameron et al. 1993, 2000; Dauphine 1976; Eloranta and Nieminen 1986; Gerhart et al.1997b; Lenvik et al.1988; Reimers 1983; Tho- mas 1982; Thomas and Kiliaan 1998; White 1983~. The intake of high quality forage often is reduced by adverse weather. A late spring snowfall or late snowmelt decreases forage quality and availability, resulting in lower birth weights (Adamczewski et al. 1987, Bergerud 1975, Eloranta and Nieminen 1986, Espmark 1979, Reimers 2002, Rognmo et al. 1983, Skogland 1984, Varo and Varo 1971) and delayed parturition (Cameron et al. 1993 Sko~land 1983, 1984), both of which reduce survival of offspring (Adamczewski et al. 1987, Eloranta and Nieminen 1986, Haukioja and Salovaara 1978, Rognmo et al.1983, Skogland 1984~. From late June through early August, repeated and often severe insect harassment reduces the frequency and duration of both suckling (Thomson 1977) and foraging bouts (Helle et al. 1992, Morschel and Klein 1997, Murphy 1988, Murphy and Curatolo 1987, Russell et al.1993, Toupin et al. 1996~. The result is less nursing opportunity, and because fewer maternal nutrients are allocated to milk- lower rates of milk intake. Factors that individually or col- lectively reduce a female's ability to raise a calf also reduce her ability to restore her body reserves, to fatten, and to breed (Crete and Huot 1993~. Tradeoffs therefore are inevitable: If maternal protein or fat reserves are not replenished fast enough, calves are weaned prematurely (Russell and White 2000~. Calf survival is reduced by early weaning, but parturition and conception rates increase (Davis et al. 1991, Russell and White 2000~. Delayed weaning enhances calf survival, but extended lacta- CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS tion precludes breeding that year (Gerhart et al. 1997a,b; Russell and White 2000~. By comparison, well-fed cows ini- tiate weaning during the rut, and both calf survival and fe- cundity are high. During August and September, when insects are absent, growth of calves and fattening of adults continue relatively unimpeded. Milk production is low (White and Luick 1984), and offspring graze actively (Russell et al. 1993) as they approach nutritional independence. Although most forage species have senesced, with a decline in quality, their high biomass permits high rates of food intake (White et al.1975) and, therefore, body-fat synthesis. Fattening is enhanced in some years by the inclusion of mushrooms in the diet (Allaye-Chan et al. 1990~. An unseasonably early, heavy snowfall, however, can disrupt the fattening process, and movement into more mountainous terrain increases expo- sure to predators. Hunting by humans tends to intensify in early autumn as well. Females that wean their calves early, together with most that are in good enough condition to wean at normal times, conceive in October (Russell and White 2000~. Cows in su- perior condition are less likely to lose their embryos early (Crete and Huot 1993, Russell et al. 1998), and, hence, are more likely to produce a calf the next spring. A dietary shift from deciduous vegetation to lichens, begun in autumn, is virtually complete by midwinter. Males and nonpregnant females typically maintain body weight (Steen 1968) even when weather and foraging conditions are unfavorable. In contrast, pregnant females, faced with the increasing metabolic demands of a growing fetus, have diffi- culty maintaining energy and nutrient balance. They metabo- lize muscle tissue and conserve body fat during the last tri- mester to support early lactation (Chan-McLeod et al. 1994, Tyler 1987~. Adequate winter nutrition increases the chances of timely parturition and early postnatal survival (Cameron et al. 1993, Eloranta and Nieminen 1986, Rognmo et al. 1983~. When snow is deep or encrusted, foraging requires more energy because caribou must dig through the snow (Fancy and White 1985a,b; Miller 1976~. Far more serious is ground-fast ice. During frequent freeze-thaw cycles, typi- cally in coastal areas during late winter or early spring, veg- etation under the snow becomes encased in ice and thus in- accessible (Miller and Gunn 1979, Miller et al. 1982~. As during autumn, mortality from predation and hunting can be appreciable. Effects on Distribution, Movements, ancl Activity Patterns Seismic Surveys Until recently, the location and timing of seismic testing resulted in few conflicts with caribou in arctic Alaska. Sur- veys on state lands through the 1990s were conducted prin- cipally within the area of the CAH summer range, but during
EFFECTS ON ANIMALS Post-calving caribou aggregation on the Arctic Coastal Plain. Photograph by Ken Whitten. winter, when caribou were largely absent. Similarly, long- term programs within the National Petroleum Reserve- Alaska during the 1970s and 1980s occurred mostly within the summer ranges of the TLH and WAH, but again during winter. Seismic exploration crews on the coastal plain of the Arctic National Wildlife Refuge in the 1980s had no contact with caribou of the PCH, which winters south and east of the Brooks Range. Even when seismic testing was conducted on winter range, the direct effects on caribou were probably temporary and minor. Early two-dimensional (2-D) surveys were of low intensity and, because wintering bands of caribou tend to be small and often widely dispersed, few caribou would have been in simultaneous contact with seismic activities. More- over, caribou appear least sensitive to human-induced dis- turbance during winter (Roby 1978~. Recently, however, both the extent and intensity of seis- mic activities have increased. Active exploration now ex- tends southward into the upper foothills of the central Brooks Range and westward to new lease tracts in the northeastern portion of the National Petroleum Reserve-Alaska. With a seismic line density 10-20 times greater than that for 2-D procedures, expanded application of the new three-dimen- sional (3-D) technology in those areas will increase the po- tential for conflicts with the CAH and TLH. Avoidance of 109 seismic lines and the attendant human activity could reduce the animals' ability to avoid areas of deep snow (Dyer et al. 2001~. The energy costs of multiple encounters with seismic disturbance could increase winter weight loss and reduce calf production and survival (Bradshaw et al. 1998~. Exploration Drilling Most exploration drilling a site-specific, high-inten- sity event is not connected to a permanent road system. As novel features on the landscape, drilling sites that are active in late spring almost certainly would be avoided by calving caribou. During midsummer, effects include local- ized changes in habitat use, longer approach distances, and altered activity patterns (Roby 1978, Wright and Fancy 1980~. Caribou did not approach a drilling site closer than 1,200 m (0.7 mi) and were seen less frequently within 2 km (1.2 mi) of a drilling site than in a control area. Those en- tering the drilling area spent less time feeding and lying and more time moving than did caribou in a control area (Wright and Fancy 1980~. In studies involving a simulated gas compressor station, caribou usually avoided the source of sound by at least 0.2 km (0.12 mi) (McCourt et al. l 974~. Sensitivity appears to decline during other seasons, when calves are older.
110 Isolated Roacis and Pipelines Perhaps as an anti-predator strategy (Bergerud and Page 1987), parturient females and postpartum females with new- born calves distance themselves from potentially threaten- ing stimuli. Aerial survey observations before and after placement of a road system (and later, an aboveground pipe- line) through a calving concentration area near Milne Point (Whitten and Cameron 1985), in the Kuparuk Development Area (KDA), illustrate that sensitivity. After construction, the density of maternal females increased with distance from roads; no relationship was apparent before construction (Dau and Cameron 1986~. Mean caribou abundance declined by more than two-thirds within 2 km (1.2 mi) of roads and was less than expected, overall, within 4 km (2.5 ml); but abun- dance nearly doubled at 4-6 km (2.5-3.7 mi) (Cameron et al. 1992), resulting in two separate concentrations (Dau and Cameron 1986, Lawhead 1988, Smith and Cameron 1992~. Road traffic was light during the study (Dau and Cameron 1986; Dau and Smith, ADF&G, unpublished data, 1986; Lawhead 1988), suggesting that the presence of a road or pipeline alone, without vehicular or human activity, can elicit avoidance. Concurrent ground observations within the KDA cor- roborate those findings. Few females and calves were seen from the road system during early June, and correspondingly few were observed crossing roads or pipelines (Smith et al. 1994~. This is consistent with a tendency for parturient fe- males to be relatively sedentary during the calving period (Fancy and Whitten 1991, Fancy et al. 1989~. A similar pattern of avoidance of a tourist resort and separate power-line corridor has been reported for semi- domesticated reindeer (Rangifer tarandus tarandus) during the calving period. Mean reindeer densities within preferred habitat were 73% and 78% lower in areas less than 4 km (2.5 mi) from the resort and power-line corridor, respectively, than in areas beyond 4 km (2.5 ml). Traffic and human activ- ity were low, again implying a dominant influence of the structures themselves (Vistnes and Nellemann 2001~. From late June through July, sensitivity to disturbance appears to decline as calves mature and are less vulnerable to predation and other sources of mortality. Maternal females are less protective and therefore less reactive to novel stimuli than during the calving period. Also, when insect harass- ment is high, caribou are less likely to avoid anthropogenic disturbances (Murphy and Lawhead 2000~. Even so, avoidance of transportation corridors can per- sist through summer. During construction of the Trans- Alaska Pipeline, 1975-1978, calves were increasingly under- represented among caribou observed from the Dalton Highway; calf percentages, on average, were 69% lower than regional estimates determined by aerial survey. Caribou sightings within, and crossings of, the pipeline corridor in 1976-1978 averaged 30% and 80% less, respectively, than did those in 1975 (Cameron and Whitten 1979b, Cameron et CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS al. 1979~. Collared males crossed the corridor more fre- quently than did collared females (Whitten and Cameron 1983~. Jakimchuk and colleagues (1987) attributed those observations to sex differences in habitat use, arguing that maternal females avoid riparian habitats to reduce the risk of predation by grizzly bears along the Sagavanirktok River, which is adjacent to the pipeline corridor. A reexamination of the data, however, revealed that bull numbers were high and calf numbers were low only within riparian areas associ- ated with the corridor (Whitten and Cameron 1986~. Young and McCabe (1998) reported neither avoidance of riparian habitats by PCH females nor selection of those habitats by bears; they also rejected the antipredator explanation. Similar avoidance was observed within the KDA, dur- ing placement of the smaller Kuparuk pipeline along the Spine Road and during construction of the first processing facility. Calves were underrepresented in groups observed in areas of heavy construction and traffic (Smith et al. 1994~. Within the CAH summer range, crossing success2 var- ies with design and juxtaposition of roads and pipelines as well as with the amount of vehicular traffic. Most early pipe- lines in the Prudhoe Bay oil-field complex (PBOC) were constructed 1 m (3 ft) or less above ground, posing physical barriers to movement (Shideler 1986~. Gravel ramps were placed over some low pipelines to encourage crossings, but anecdotal observations indicated that caribou made limited use of those structures. In the adjacent KDA, however, all ninelines were elevated at least 1.5 m (5 ft), and ramps were built at road intersections. Curatolo and Murphy (1986) re- ported no selection for particular surface-to-pipe clearances within the range of 1.5-4.3 m (5-14.1 ft), indicating that, under most conditions, the regulatory standard of 1.5 m (5 ft) is sufficient for caribou crossings (Cronin et al. 1994, Curatolo and Murphy 1986~. However, crossing success at elevated pipelines close to roads with traffic was lower than for pipelines without associated roads and traffic (Curatolo and Murphy 1986~. Large mosquito-harassed groups had particular difficulty negotiating road-pipeline corridors (Child 1974; Curatolo and Murphy 1986; Fancy 1983; Smith and Cameron 1985a,b). Crossing success appears to increase during the oestrid fly season, but it is unclear whether that is attributable to the presence of smaller groups or to different reactions to the two insect pests (Smith and Cameron 1985a). Under some circumstances, ramps enhance pipeline cross- ings (Child 1973, Cronin et al. 1994, Curatolo and Murphy 1986, Shideler 1986, Smith and Cameron 1985b). Effects on caribou activity near road-pipeline corridors are most pronounced when there is no insect harassment. During insect-free periods, maternal and nonmaternal groups 2 Curatolo and Murphy (1986) considered a crossing successful when more than half of an observed group crossed a road and/or pipeline (or a hypothetical pipeline in a control site). Success was then expressed as a percentage which was evaluated statistically by comparison with the corre- sponding "expected" percentage obtained from the control site.
EFFECTS ON ANIMALS within 600 m (2,000 ft) of a corridor with traffic spent less time lying and more time moving than did controls. Mater- nal groups and groups of more than 10 individuals were most reactive to disturbance (Murphy 1988, Murphy and Curatolo 1987). From autumn through early spring, the CAH has con- siderably less contact with industrial development. By the autumn rut, most of the herd has moved well inland (Cameron and Whitten 1979a). Only those few caribou that winter on the coastal plain are likely to interact with oil fields, and the effects appear to be minor. However, females with calves avoided inland portions of the Trans-Alaska Pipeline corridor during its construction. Calf percentage for caribou near the Dalton Highway was approximately repre- sentative of regional percentages in 1975, but diverged dur- ing 1976-1978, averaging 32% less than regional estimates. Sighting frequency declined about 60%, relative to the 1975 estimate, but crossing rates were inconsistent (Cameron and Whitten 1979b, Cameron et al.1979~. Overall, avoidance of the pipeline corridor by females with calves decreased mea- surably between summer and autumn, correlated with the advanced age of the calves and distractions of the rut. Ha- bituation to construction activity is also a possibility. Oil-Fielcl Complexes Given that calving caribou avoid roads and pipelines (Cameron et al. 1992, Dau and Cameron 1986), their densi- ties should be reduced in areas with corridors closer together than some minimum distance. In fact, the proportion of calv- ing caribou in the densely developed western portion of the KDA declined significantly from 1979 through 1987 (Cameron et al.1992~. Concentrated calving activity shifted inland from the Milne Point area beginning about 1987 (Lawhead et al. 1993, 2001; Murphy and Lawhead 2000; Wolfe 2000), associated with the increasing density of oil- field infrastructure. Caribou did not abandon the area near Milne Point (Lawhead et al. 2001, Nellemann and Cameron 1996), but continued to occupy the KDA in numbers consis- tent with the amount of undisturbed habitat. Other explana- tions advanced for the inland shift west of the Sagavanirktok River include expansion of the calving ground with increas- ing herd size, changing vegetation characteristics, and para- site avoidance (Lawhead et al. 2001~. One or more of these factors could have accelerated that process. However, none explains the absence of a similar shift by the undisturbed part of the caribou herd east of the Sagavanirktok River (Wolfe 2000). During the summer insect season, dense surface devel- opment within the PBOC also altered the distribution of cari- bou, especially females with calves. As early as 1978, mean calf percentage in the core area of the industrial complex was less than half the minimum regional estimate (Smith and Cameron 1983~. With continued growth of the complex, changes in caribou distribution became even more pro- 111 pounced. An analysis of more than 1,200 point locations of 141 radio-collared females (Cameron et al. 1995) suggests that caribou use of the area has declined substantially from that noted by Child (1973), White and colleagues (1975), and Gavin (1978~. From 1980 through 1993, abundance within and east-west movements through the area were lower than for other areas along the arctic coast. Conservative cal- culations yielded an estimated 78% decrease in use and a 90% decrease in lateral movements. Other researchers (Cronin et al. 1998, Pollard et al. 1996a) concluded that the PBOC infrastructure has had little effect on the midsummer distribution of caribou. However, their findings do not appear to support that conclusion. With- out spatial controls undeveloped areas they lacked the ability to compare the distribution of cows with calves in the field as a whole with that in either the denser central area or in the less-developed areas to the northwest. Many caribou, including some females and calves, do periodically use the PBOC, particularly the less-developed northwestern areas (Ballard et al. 2000, Murphy and Lawhead 2000~; but data reported by Pollard and colleagues (1996a) indicate that cari- bou were numerous there only during periods of moderate or high insect harassment and that females with calves gener- ally were underrepresented. These latter data and evidence for reduced abundance and movements of females with the complex (Cameron et al. 1995, Smith and Cameron 1983) indicate that patterns of use by caribou have been apprecia- bly altered. Changes in Habitat Use Ecological theory and data support the premise that ani- mals generally select the best available areas for reproduc- tive activity. For calving CAH caribou, the probable conse- quence of disturbance-induced changes in distribution is selection of lower-quality habitats. The number of caribou affected is directly related to the area and intensity of distur- bance, which could range from the localized avoidance of an isolated road to a regional shift of a large calving concentra- tion away from areas occupied by multiple oil-field com- plexes. With the gradual loss of access to preferred foraging habitats, increasingly more females seek "next best" avail- able areas. As those areas become insufficient to accommo- date the population, use declines at a rate proportional to the increase in density of structures (Nellemann and Cameron 1998, UNEP 2001~. The shift in calving activity west of the Sagavanirktok River might have increased predation risk, particularly in recent years. Since at least 1995, the inland calving concen- tration west of the river has overlapped extensively with rela- tively high densities of brown bears (R. Shideler, ADF&G, unpublished data, no date). However, estimates of calf sur- vival during 1988-2001 were similar west and east of the river (84% and 88%, respectively; P = 0.426) (Table 8-1), implying that any increase in mortality attributable to preda-
112 CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS TABLE 8-1 Parturition Rates of Radiocollared Female Cariboua and Summer Survival of Their Calves, West and East of the Sagavanirktok River,b during 1988-1994C and 1998-2001.4 Central Arctic Herd, Alaska. Parturition rate, Be (n) Calf survival, Of (n) Years(s) West East Pg West East Pg 1988 72.7 (11) 100.0 (8) 66.7 (6) 100.0 (6) 1989 53.8 (13) 77.8 (9) 83.3 (6) 60.0 (5) 1990 83.3 (12) 100.0 (7) 85.7 (7) 60.0 (5) 1991 45.5 (11) 75.0 (12) 1992 72.7 (11) 75.0 (12) 87.5 (8) 100.0 (9) 1993 55.6 (9) 62.5 (8) 100.0 (5) 100.0 (5) 1994 66.7 (6) 87.5 (8) 75.0 (4) 85.7 (7) 1988-1994 64.3 + 5.0 82.5 + 5.3 0.003 83.0 + 4.6 84.3 + 8.0 0.898 1998 92.3 (13) 100.0 (6) 90.9 (11) 100.0 (6) 1999 100.0 (13) 100.0 (8) 88.8 (9) 100.0 (8) 2000 83.3 (12) 90.0 (10) 77.8 (9) 77.8 (9) 2001 90.9 (11) 100.0 (7) 80.0 (10) 100.0 (5) 1998-2001 91.6 + 3.4 97.5 + 2.5 0.062 84.4 + 3.2 94.4 + 5.5 0.091 All years 74.3 + 5.3 88.0 + 4.1 0.001 83.6 + 2.9 88.4 + 5.3 0.426 a All sexually mature. b Individual locations consistently west (oil field development present) or east (no surface development, except for the Badami pipeline and oil field beginning in 1996) during the calving period. c Forty-three females observed for 2-7 years (Cameron 1995; Cameron et al. 2002). Twenty-nine females observed for 2 - years (Lenart, ADF&G, unpublished data, 2002). e Based on parturition status determined by fixed-wing aircraft (Cameron et al. 1993). f Percentage of parturient females with calf at heel 2-6 weeks postpartum. g T-test, paired comparisons. Mean and standard errors shown. tion was compensatory (that is, predation on calves predis- posed to die from other causes). Oil-field infrastructure also can delay access to insect- relief areas and foraging habitats. In the KDA, the lower success of or delays in crossing road-pipeline corridors by large insect-harassed groups of caribou (Curatolo and Murphy 1986, Murphy 1988, Murphy and Curatolo 1987, Smith and Cameron 1985b) apparently encouraged a general shift to peripheral areas of the complex with less surface development and human activity (Smith et al. 1994), sug- gesting that caribou were impeded in their efforts to move between coastal and inland habitats. Much of the PBOC poses a behavioral, if not a physical, barrier to movement of adult females at times (Cameron et al. 1995, Whitten and Cameron 1983~. Radio-collared fe- males were scarce in the most densely built (and oldest) part of the complex (Figures 8-4 and 8-5), especially when in- sects were relatively inactive. During periods of moderate to high insect activity, caribou south of the complex often di- vert eastward, into the prevailing northeasterly winds, to the Sagavanirktok River and move downstream to the coast (Lawhead et al. 1993~. Alternatively, caribou might occupy gravel pads for insect relief (Noel et al. 1998, Pollard et al. 1996b, Truett et al. 1994) when other habitats are unavail- able (Wolfe 2000~. Changes in distribution and movements during calving and when insects are present reduce the capacity of the range to support CAH caribou. This is due to loss of preferred habi- tats (Cameron et al. 1995, Wolfe 2000) and through corre- spondingly greater use of lower-quality habitats (Klein 1973, Nellemann and Cameron 1996, Wolfe 2000~. Nutritional and Reprocluctive Implications The reproductive success of arctic female caribou is highly correlated with their nutritional status. Parturition rate varies directly with body weight or fat content during the previous autumn (Cameron and Ver Hoef 1994; Cameron et al. 1993, 2000; Gerhart et al. 1997a), whereas calving date and survival within about 48 hr after birth are more closely related to maternal weight at the time of parturition (Cam- eron et al. 1993~. Those relationships form the link between the distur- bance-induced changes in distribution described above and potential changes in reproductive success. Based on an analysis of 96 radiocollared females at 183 calving sites from 1980 to 1995, Wolfe (2000) reported a shift in concentrated calving from developed coastal areas west of the Saga- vanirktok River to inland habitats with lower green-plant biomass.3 On the east side of the river, an area without 3 Relative levels of biomass were inferred from the normalized differ- ence vegetation index (NDVI), which is a measure of relative land-cover greenness. Numerous factors can affect the NDVI, including the amount of green biomass, dominant plant species, the amount of standing dead vegeta- tion, lakes, bare soil, and rock (Walker et al. 2003). 7 ~
FICURE 8-4 Roads Ed pipeUnes in me P~~oe BE region, Alaska, circa 1990. Dog: One or more pipeUnes (suppled) He Percent to most roads. SOURCE: C~eron et at. 1995. Repriced Aim permission, copyright 1995, R~ngi~. FICURE 8-5 Locus of r~dio-coU~ed Me caribou Timid 850-~2 coasts quits in seldom to insect ~cUvi~. Ceded Arctic Herd, Alaska, summer 1980-1993. God: Some points represent >1 Me in ~ Angle group. SOURCE: Cameron et AL 1995. Repined Aim permission, copyright 1995, Raging.
114 development, no such shift in calving was observed: Females selected habitats with above-average green-plant biomass (Wolfe 2000~. For the PCH, calf survival through their first few weeks is primarily a function of the relative amount of forage available on the annual calving ground during the peak lactation period (Griffith et al. 2000, 2002~. However, survival estimates (Table 8-1) and Wolfe's (2000) NDVI data do not suggest such a relationship for the CAH, but sample sizes are small. Impaired movements during the insect season also could decrease energy balance (Murphy and Lawhead 2000, Russell 1976, Russell et al.1993, Smith 1996, Weladji et al. 2002, White et al. 1975) and hence reduce rates of summer weight gain. However, changed activity patterns of caribou near transportation corridors (Murphy 1988, Murphy and Curatolo 1987) might not reduce weight gain enough to de- press parturition rates (Murphy et al. 2000~. Nevertheless, individual or collective conflicts that result in nutrient insuf- ficiency can decrease fecundity. In fact, from 1988 through 1994 the mean parturition rate for radio-collared females exposed to oil development west of the Sagavanirktok River was 64%, compared with 83% for the relatively undisturbed females east of the river (P = 0.003~. Parturition rates were similar from 1998 through 2001 (92% and 98%, respectively; P = 0.062), but differed for the eleven years overall (74% and 88%, respectively; P = 0.001) (Table 8-1~. Estimated frequencies of reproductive pauses (periodic failure to produce a calf because of poor condition at breeding) (Cameron 1994, Cameron and Ver Hoef 1994) for the combined data were 26% and 12%, or approximately one pause every 4 and 8 years, respectively. This longitudinal analysis provides a reliable assessment of differences in reproductive success. Because radio-col- lared females were used, interannual shifts of individual fe- males between areas west and east of the Sagavanirktok River (Cronin et al.2000; Lawhead and Curatolo 1984, cited in Murphy and Lawhead 2000; Whitten and Cameron 1983) could be detected and samples adjusted accordingly, yield- ing multiyear histories of parturition rates for females with consistent use of the two areas. Lower fecundity of females west of the river could be due to inadequate compensation for milk production (Cameron and White 1992~. By reducing rates of forage in- take and increasing rates of energy expenditure, conflicts during the calving and insect periods might diminish chances of achieving the weight gain required to support annual re- production (Cameron and White 1992, Russell et al. 2000~. In general agreement are anecdotal reports from Nuiqsut resi- dents that caribou taken recently have been leaner than in years past (Miller 2001, Pedersen et al. in press). Population Dynamics Observed changes in the size of the CAH (Figure 8-6) are correlated with estimates of net calf production the CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS 30 CO ° 20 _ x N . _ U' I 10 _ O _ (a) i 100~ (b) a ~ 80 _ tL He 60 _ 40 _ 30 (C) I In in 20 _ 10 _ \e ~ '~V': J - 80 84 88 Year 92 96 00 FIGURE 8-6 Central Arctic Herd in Alaska. (a) Herd size, 1978- 2000. Point estimates determined by photo-census. (b) Net calf pro- duction. Three-year moving averages of radio-collared female cari- bou, 1981-2000. SOURCES: Data from ADF&G files, Lenart 2001. Percentage of parturient females with a calf at heel 2-8 weeks postpartum; approximate equivalent of the product of parturition rate and over-summer calf survival (see Table 8-1~. (c) Number of insect days in July. Three-year moving averages, 1980-1999. SOURCES: Weather data for Deadhorse Airport, Alaska State Cli- mate Center, UAA applied to the predictive models of Russell et al. (1993~; criteria for insect days from Cameron et al. (1995~. product of parturition rate and calf survival. From 1978 through 1983, when the herd increased, on average, 16% annually, net calf production exceeded 90%. The next cen- sus was not done until 1992, so the trajectory in herd size during the intervening period is not known; but the steady decrease in net calf production implies a deceleration of growth though the early 1990s. Between 1992 and 1995, years with consistently low productivity, the CAH actually declined by about 8% per year. From 1995 until the census in 2000, the herd increased 14-15% annually, correlated with a sustained increase in net calf production. Net calf production is affected by factors that influence acquisition and retention of energy and nutrients. An impor- tant factor is insect activity. From 1981 through 2000, net
EFFECTS ON ANIMALS 100 80 so on cC 60 o . _ . _ ILL 40 20 West East ilk _ "Kirk 1 Low Insect Activity High FIGURE 8-7 Parturition rates of 72 radio-collared female caribou of the Central Arctic Herd in Alaska west and east of the Saga- van~rktok River, 1988-2001, following years of low and high insect activity, determined, respectively, as the number of insect days below and above the median of 20.5 days (range, 15-27) for 1987-2000 (see Figure 8-6 legend). UP= 0.043, paired l-test. **P = 0.004, paired l-test. SOI~CES: Data from ADF&G files, Lenart 2001. calf production was inversely correlated with the number of days of high insect activity in July of the previous year (Fig- ure 8-7) (Spearman's rank, P = 0.012~. A lower frequency of insect-induced movements and insect avoidance behavior enable caribou to spend more time in high-quality habitats, thereby increasing chances that they will eat enough to pro- duce milk. Maternal females would then experience greater weight gain, superior condition at breeding, and a higher probability of producing a calf the following spring. Fre- quent or prolonged insect harassment would have the onno- site effect. Because parturition rate accounts for most of the vari- ability in net calf production (Table 8-1), the committee fo- cused on differences in parturition rate that might be related to level of insect activity. Classifying the 11 paired estimates of parturition rate west and east of the Sagavanirktok River into (previous) years of low and high insect activity yielded significant differences within each category (P = 0.043 and P = 0.004, respectively; Figure 8-7~. When insects were rela- tively inactive, mean parturition rate of females west of the river was only about 10% lower than for those to the east. Following years of relatively high insect activity, however, the reduction was more than 25%. Thus, oil-field development, by delaying or deflecting movements of caribou within and between habitats (Murphy and Lawhead 2000; Smith and Cameron 1985a,b; Smith et al. 1994), probably exacerbates the adverse effects of insect harassment. If the ability to forage or escape insects is suffi- ciently reduced, nutrition and fecundity will decline, with direct consequences for herd growth. Indeed, decreasing herd size from 1993 to 1995 (Figure 8-6) was associated with relatively high insect activity (2 of 3 years, 1992-1994~. The subsequent trend of increasing size from 1996 to 2000 oc- 115 curred during a period of generally low insect activity (3 of 5 years, 1995-1999~. Net growth of the CAH over the past 25 years is not, by itself, sufficient evidence for the absence of any adverse ef- fect of petroleum development on caribou (WMI, unpub- lished material, 1991~. We cannot know what the growth trajectory of the herd would have been in the absence of oil- field development. However, multiyear data on the repro- ductive performance of collared CAH females exposed to oil-field development, relative to an undisturbed reference group, indicate that productivity did decline when the atten- dant disturbance and habitat losses were superimposed on other conditions that adversely affected nutrient balance. Future Effects The results of the committee's analysis of the consequences of petroleum-related disturbance to CAH caribou provide a ba- sis for assessing the probable future effects on the CAH and other arctic herds of the likely expansion of oil and gas develop- ment over the next 25 years. The expansion will likely be east- ward on state lands from the Badami unit, southward into the foothills of the central Brooks Range, and westward into the National Petroleum Reserve-Alaska from the Alpine unit. Un- less the density of new access roads and new production and support facilities can be substantially reduced relative to infra- structure now in place, conflicts with CAH caribou east of the Sagavanirktok River will increase during the calving and in- sect-harassment periods. Higher insect activity associated with climate warming (Klein 1999) could counteract benefits of re- duced surface development by increasing the frequency with which caribou encounter infrastructure. With inland expansion, more of the CAH will come into contact with development on its winter range, with unknown consequences. If the calving ground of the TLH continues to be protected, direct conflicts with parturient females of that herd are unlikely, provided that their movements are not im- peded. However if inland lease tracts in the northeastern por- tion of the National Petroleum Reserve-Alaska are developed, effects on midsummer distribution, habitat use, and produc- tivity of TLH caribou are possible. The exact outcome and the degree to which these effects would accumulate depend on a host of unknowns, including characteristics of the oil and gas reservoir and advances in extraction technology. Within the next 25 years, major expansion of industrial activity into the WAH calving ground is unlikely, and inroads to its primary summer range are expected to be modest. If so, effects should be minor and not accumulate significantly. If a proposed road north of the Red Dog mine to a North Slope site of a coal-fired power plant were constructed, it would cross a major east-west zone of caribou travel, possi- bly interfering with insect-induced movements. A road would also open the region to further development. To date, oil and gas activities have had little influence on the PCH, but petroleum exploration and subsequent develop-
116 ment on the coastal plain (1002 Area) of the Arctic National Wildlife Refuge could lead to conflicts on the calving ground of that herd. To assess the potential effects of such develop- ments on the PCH, Griffith and colleagues (2002) combined pertinent information on the CAM with the extensive data on the PCH. They simulated the effects of progressive develop- ment of the 1002 Area by displacing 17 annual calving grounds, between 1985 and 2001, using five scenarios (slough et al.1987~. The concentrated calving area within each annual calving ground was repositioned 4 km (2.5 mi) from the pe- riphery of industrial infrastructure. June calf survival was then calculated for each annual calving ground observed and for those hypothetically displaced, using a predictive model based on green-plant biomass during peak lactation and predation risk. A significant (P < 0.0001) inverse relationship was ob- tained between change in calf survival and displacement dis- tance, even though calving still remained primarily on the coastal plain where habitat was good for foraging and preda- tor avoidance. The results of these simulations suggest that an average displacement of approximately 27 km (17 mi) would be sufficient to halt growth of the PCH. Consequences similar to those reported for the CAH are possible on PCH summer range, depending upon the extent and intensity of surface development. Impaired movements during years of high insect activity could reduce weight gain of lactating females, with comparable effects on fecundity (Figure 8-7~. If superimposed on reduced calf survival (Griffith et al. 2002), the additive effects on PCH productiv- ity could be substantial. The PCH has the lowest growth capacity of the four arctic herds and, consequently, the least resistance to natural and anthropogenic stresses (Griffith et al. 2002~. That vul- nerability is, in part, attributable to the critical importance during calving of free access to the highest quality foraging and predator-avoidance habitats and to a lack of suitable al- ternative habitats (Griffith et al. 2002~. It is impossible to characterize future development in- frastructure and activity in areas that have not been fully explored. Until exploration has occurred, the amount, distri- bution, and exact nature of any extractable hydrocarbon de- posits remain unknown. But the amount, distribution, and type of hydrocarbon deposits profoundly influence the na- ture and extent of development infrastructure, thus how many roads and pipelines will be needed, and how much activity will occur and when it will occur. Current technol- ogy will probably continue to evolve, as discussed elsewhere in this report, but adverse effects on caribou are likely to increase with both the density of infrastructure development and the area over which it is spread. Finclings . The intensively developed PBOC has altered the dis- tribution of female caribou during the summer insect season. Elsewhere, a network of roads, pipelines, and facilities has CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS interfered with their movements between coastal insect-re- lief and inland feeding areas. · Radio-collared female caribou west of the Saga- vanirktok River shifted their calving concentration area from developed areas nearer the coast to undeveloped areas in- land. No such shift has occurred for caribou calving east of the Sagavanirktok River where there is no development. The shift by caribou west of the Sagavanirktok River was into an area with lower green-plant biomass than the area previously used. From 1988 to 1994, parturition rates of radio-collared females in regular contact with oil-field infrastructure west of the Sagavanirktok River were lower than those of undis- turbed females to the east. Reduction in parturition rates- the variable part of net calf production for those caribou was exacerbated by intense insect harassment during the period. Thus, it appears that the effects of oil-field develop- ment accumulate with effects of insect harassment by im- pairing movements between coastal and inland habitats. · Possible consequences of these disturbances include reduced nutrient acquisition and retention throughout the calving and midsummer periods, poorer condition in autumn, and a lowered probability of producing a calf in the follow- . . ng spnng. · As a result of conflicts with industrial activity during calving and an interaction of disturbance with the stress of summer insect harassment, reproductive success of Central Arctic Herd female caribou in contact with oil development from 1988 through 2001 was lower than for undisturbed fe- males, contributing to an overall reduction in herd produc- tivity. The decrease in herd size between 1992 and 1995 may reflect the additive effects of surface development and rela- tively high insect activity, in contrast to an increase in the herd's size from 1995 to 2000, when insect activity was gen- erally low. · Expanded loss of preferred habitats, which could ac- company the spread of industrial activity across the National Petroleum Reserve-Alaska and into the foothills of the Brooks Range, and climate change that increases insect ha- rassment, are likely to depress energy and nutrient status and, therefore, summer weight gain of lactating females. · Unless future requirements for infrastructure can be greatly reduced, exploitation of oil and gas reserves within the calving and summer ranges of the CAH, TLH, and PCH will likely have similar consequences. Recommenclations · Determine the responses of caribou to seismic test- ing under different snow conditions and estimate the prob- able consequences in terms of energy intake and nutrient balance and reproductive success. · Determine the minimum distance between road-pipe- line corridors that is compatible with continued use of an area by calving caribou and how design of corridors influ- ences those effective distances.
EFFECTS ON ANIMALS · Studies are needed to characterize the nutrient-en- ergy tradeoffs associated with insect-induced movements; quantify the conditions of food intake and body condition associated with each of the various weaning decisions (tradeoffs) made by maternal females; and within known lev- els of exposure to disturbance, determine the over-summer nutritional performance of females and their calves. · Determine whether winter calf mortality is additive or compensatory, relative to early postnatal mortality; that is, do those that survive unfavorable foraging conditions in spring or summer die during the winter anyhow? MUSKOXEN Muskoxen (Ovibos moschatus), which were extermi- nated from Alaska, have been reintroduced and are now found at low densities on the North Slope, mostly in riparian areas. Populations are expanding into other habitats. Heli- copters and low-flying aircraft sometimes cause muskoxen to stampede and abandon their calves (Winters and Shideler 1990~. Seismic exploration is of concern because muskoxen are present year-round on the North Slope. The response to the noise of seismic exploration appears to differ from herd to herd, perhaps because of each herd' s previous experience. Some seem unaffected by seismic activities as close as 300 m (980 ft); others appear disturbed by activity 10 times more distant (Winters and Shideler 1990~. Therefore, although no adverse effects have been recorded to date, the expansion of 3-D seismic exploration to primarily unsurveyed areas, par- ticularly in riparian areas, could result in increased distur- bance to this species. Finding No effects of seismic exploration on muskoxen have been detected to date. However, the expansion of 3-D seis- mic exploration to new areas, particularly in riparian areas, might increase disturbance to this species. ARCTIC FOXES Past and current industrial activities on the North Slope have probably increased the availability of shelter and food for the arctic fox (Alopex lagopus). Developed sites within the Prudhoe Bay oil field are used by foxes for foraging on garbage and handouts, and for resting. Foxes do not avoid human activity successful litters of pups have been raised within 25 m (80 ft) of heavily traveled roads and within 50 m (160 ft) of operating drill rigs. Foxes use culverts under roads, underground utility corridors in camps, and sections of natural gas pipe as dens (Eberhardt et al. 1982~. In Prudhoe Bay, foxes use developed sites more in win- ter, when food is more likely to be scarce, than in summer. In December radio-tagged foxes spent much of their time on and around developed sites, with large concentrations near 117 dumps and other developed areas (Eberhardt et al. 1983a). During summer, garbage was commonly found at den sites near Prudhoe Bay (Garrott et al. 1983~. The density and rate of occupancy of dens and the sizes of litters are greater in oil fields than in adjacent areas, so the fox population has grown larger and more stable (Burgess 2000, Eberhardt et al. 1982, 1983b). To reduce the possibil- ity of transmission of diseases, especially rabies, to humans, oil companies have developed employee education programs and have trapped and removed foxes (Burgess 2000~. With careful employee education and proper refuse-handling pro- cedures, disease-transmission problems with arctic foxes can be reduced. Another issue of concern is the foxes' potential to affect populations of nesting birds. Birds are a normal prey (Garrott et al.1983), and migratory species can provide an especially important food source (Stickney 1991). Future Effects In the scenario the committee has used for future devel- opment, oil and gas exploration and production would occur on the entire Arctic Coastal Plain outside of the Arctic Na- tional Wildlife Refuge. The arctic fox population is likely to increase throughout that region. The current concerns about foxes would then be applied to a more expanded area. A long-term higher density of foxes could result in reduced nesting success and smaller regional populations of some species of birds (Burgess 2000~. Effects of predation can be locally devastating to colo- nial birds that nest in areas normally inaccessible to foxes (Quinlan and Lehnhausen 1982~. Human modifications to habitats, such as roads or causeways that connect barrier is- lands to the mainland, could cause serious problems in such circumstances. Such effects would accumulate as more area is developed and as a larger portion of a bird population's nesting habitat is affected by increased fox predation. Other factors would interact cumulatively with indus- trial development to influence arctic fox populations on the North Slope over the next 25 years. In particular, habitat characteristics and abundances of prey, competitors, preda- tors, and disease agents could change greatly with climate warming. Although it is likely that there will be more arctic foxes in developed areas in the immediate future, it is not possible to predict long-term patterns of their abundance. Finding The increased fox populations due to oil and gas activi- ties could affect regional populations of some bird species. GRIZZLY BEARS The infrastructure that supports industrial development in the Arctic substantially increases bear-human interactions.
118 These interactions might have created a population sink as- sociated with industrial infrastructure that could lead to long- term effects on grizzly bear populations on the North Slope. Development in the central Arctic increased potential hunter access by road and airstrip (Shideler and Hechtel 2000~. Defense of life and property (DLP) mortality of griz- zlies arises with increases in human residence and anthropo- genic food availability. Shideler and Hechtel (2000) found that 21% of oil-field grizzlies supplemented natural forage with anthropogenic foods. When access to garbage and hu- man food was suddenly eliminated, food-conditioned bears suffered DLP mortalities greater than sustainable rates (Shideler and Hechtel 2000; R. Shideler, ADF&G, personal communication, 2002~. Studies of the grizzly bear populations that use Prudhoe Bay oil fields showed that bears that consumed human food resources had higher than average cub survival (possibly because of a scarcity of natural predators such as wolves, wolverines, and adult male bears). This increased cub sur- vival was offset by greater-than-average mortality among post-weaned subadults because their conditioning to human foods made them more vulnerable to hunters along the Dalton Highway and to DLP killings (Shideler and Hechtel 2000~. Bears are often drawn into human camps by simple curiosity or cooking odors; however, once there they often remain because of deliberate feeding which is now rela- tively unusual or by improperly stored food and garbage, which can lead to additional grizzly bear mortalities. A1- though efforts have been made to reduce food available to bears, they have been only partly successful because some individuals have become expert at defeating them. In the Prudhoe Bay oil fields, the mortality rates of all adults and subadults that fed on anthropogenic foods was significantly higher than for bears that fed on natural foods (Shideler and Hechtel 2000~. Of 12 offspring weaned by 4 food- conditioned females, 7 were killed, the status of 2 was un- known, and only 3 are known to have survived (Shideler and Hechtel 2000~. During the summer of 2001, 5 food- conditioned bears were killed in the Prudhoe Bay oil fields (R. Shideler, ADF&G, personal communication, 2002~. These DLP kills are an example of the risks facing grizzly bears following industrial development in wilderness habi- tat. Of 9 known grizzly bear deaths associated with oil- field development, all were within the support service en- claves outside the immediate control of the oil companies (R. Shideler, ADF&G, personal communication, 2002~. On the basis of this experience, support areas appear likely to be a source of human-bear interactions. Western arctic grizzly populations are low, and they are vulnerable to increasing harvest rates. Northern and north- western areas of the western Arctic are marginal grizzly bear habitat (R. Shideler, ADF&G, personal communication, 2002), but grizzlies can be lured out of the foothills to food sources on coastal plain habitats. Seismic exploration, par- CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS ticularly new three-dimensional techniques, could disrupt donning (R. Shideler, ADF&G, personal communication, 2002~. Future Effects Expanded oil and gas exploration and production on the North Slope does not appear likely to have a large effect on bear populations, especially if the attention to the issue of bears and garbage continues. If some bears continue to be food-conditioned, some of them probably will be killed when their food source is removed. Also, bear predation on other species such as caribou could increase (Shideler and Hechtel 2000~. Even with the best possible mitigation programs, there will always be interactions with humans who live and work in grizzly bear habitat, and some bears will be killed in de- fense of life and property or by accident. Also, increased access opportunities (roads and airstrips) and changes in vil- lage lifestyles or economies could result in more bears being killed for sport or subsistence. Construction of industrial facilities results in alteration or destruction of grizzly bear habitat, and as the amount of developed area expands so will the effect on bear habitat. Issues of potential concern are the effects of disturbance from roads and from seismic exploration on donning habitat and on bears in dens, and habitat alterations that influence food availability (R. Shideler, personal communication, 2002~. Those effects will be greater when development expands into the foothills because grizzly bear densities are higher there than on the coastal plain (Carroll 1995, Stephenson 1995~. It is also very likely that in the next 25 years the nature of habitats available to grizzly bears on the North Slope will be affected by climate warming. How the effects on grizzly bears of development-related killing of bears, hunting, alter- ations of habitat, and climate warming will accumulate can- not be predicted. Finding Oil and gas activities on Alaska's North Slope have changed the demographics of the grizzly bear population primarily because of the availability of anthropogenic food sources. BIRDS To assess the accumulation of effects of oil and gas ac- tivities on birds it is necessary to understand factors that limit avian populations in areas influenced by the petroleum in- dustry. This task is complicated because migratory species can be affected by factors away from the oil fields. The lim- iting factors generally involve habitat, but there are associ- ated variables, such as the availability of food in wintering and migration areas and of the food birds need for mainte-
EFFECTS ON ANIMALS nance and production of eggs or tissue in the breeding area. Hunting, primarily of waterfowl, also is of concern, as is predation on eggs, young, and adults. Habitat change in win- tering or migration areas can reduce populations that breed in oil development areas independent of local effects or can keep breeding populations below local carrying capacity. Reduced winter habitat could hamper first-year or adult sur- vival or reduce the proportion of breeding adults by altering their ability to store nutrients required for migration and re- production (Ankney 1982, Ens et al. l990~. Also, large molt- ing concentrations of pintails (Anas acuta), long-tailed ducks (Clangula hyemalis), king eiders (Somateria spectabilis), and black brant (Branta bernicla nigricans) use Alaska's North Slope and adjacent lagoons for postbreeding molting and migration. Declines in breeding populations away from the North Slope could cause declines in northern Alaska in- dependent of local industrial activities. Such cross-seasonal effects are difficult to measure and will be considered only in the context of evaluating local effects in developed areas on Alaska's North Slope. Dynamics of Habitat Habitat for breeding and molting birds has been directly affected by placement of gravel fill (Gilders and Cronin 2000, Walker et al. 1987a) and by thermokarst (Walker and Everett 1987~. There have been several indirect effects: Dust shadows on the leeward side of roads and gravel pads can accelerate snow melt and alter the condition of plant com- munities (Walker and Walker 1991~. Drifted snow on the windward sides of roads can delay snowmelt, and the dam- ming effects of roads can create impoundments (Kertell and Howard 1997, Walker 1996~. Almost 3% of the area of cur- rent oil fields is covered by gravel, although newer develop- ments require only about one-tenth the amount of gravel fill that was required for the earliest oil fields (Gilders and Cronin 2000~. The area affected by thermokarst and im- poundment associated with gravel fill is approximately double the area covered by gravel. Raptor densities are concentrated inland from existing oil fields, especially along the Colville River, which has one of the highest densities of nesting raptors anywhere on Earth. Past development probably has not measurably affected those populations. Rough-legged hawks (Buteo lagopus) and ravens (Corvus corax) might have benefited slightly from development because they use anthropogenic structures for nest platforms (Day 1998, Ritchie 1991~. The power lines that are ubiquitous in older oil fields cause minor mortality of migrating birds in other regions (e.g., Faanes 1987~. One study detected 4 collisions and re- ported 31 dead birds over 2 years (Anderson and Murphy 1988~. Correcting for detection bias (dead birds scavenged before being found), Anderson and Murphy (1988) estimated 1 collision for every 1,000-7,000 flights across the power line, which was at the low end of reports from other studies 119 of bird collisions with powerlines. Nonetheless, if rare spe- cies or pre-breeding adults are among the colliders, these could be effects of importance for those particular species. Individuals from 15 avian species were identified; no spe- cies was represented by more than three individuals (B. Anderson, ABR Inc., unpublished data, 1988~. Five of the carcasses were identifiable only as waterfowl. Potentially sensitive species represented in the sample of carcasses in- cluded long-tailed ducks (three individuals) and an unidenti- fied eider. Given the small numbers representing any indi- vidual species, power line collisions are unlikely to represent an important source of mortality in the oil fields. This source of mortality is likely to remain confined to the core areas of the Prudhoe Bay and Kuparuk oil fields if new fields con- tinue the recent trend of placing power lines on pipeline sup- ports or burying them in roads. Tuncira Poncis Spills that contaminate tundra ponds could cause sig- nificant damage to the ponds and to birds that use them. If oil becomes trapped in sediments, preventing weathering, the effects on organisms can persist as fresh oil emerges. Miller and colleagues (1978) studied tundra ponds affected by natu- ral oil seeps and experimental spills. Zooplankton was virtu- ally eliminated, although phytoplankton productivity, which was reduced initially, returned to normal. Recovery can take several years, however. Data from experimental spills sug- gest that recovery could be enhanced by the addition of nu- trients to stimulate the growth of oil-degrading organisms (Bergstein and Vestal 1978, Horowitz et al. 1978~. Preclators Birds and their nests in the oil fields have a suite of predators, the most important of which are arctic foxes, glau- cous gulls (Laws hyperboreus), grizzly bears, and ravens. The populations of all of those predators have increased in the oil fields (Burgess 2000, Burgess et al. 1993, Eberhardt et al. 1982, Truett et al. 1997), most likely because of the increase in garbage. Gull populations are on the rise through- out the Arctic (Bowman et al.1997, Kadlec and Drury 1968, Mallek and King 2000, Vermeer 1992), however, so it is not clear whether the increases in the oil fields are part of a glo- bal pattern or associated with local changes caused by oil development (Day 1998~. Day (1998) cites numerous ac- counts of heavy use on the North Slope of landfills, includ- ing those in the oil fields, for foraging by glaucous gulls. Bircl Species of Special Concern Loons Pacific loons (Gavia pacifica) sometimes nest on the shores of impoundments (Kertell 2000), so increases in im-
120 pounded water in developed areas could be beneficial to this population if productivity on impoundments is similar to that in natural wetlands. Kertell and Howard (1997) were unable to detect important limnological differences between natural wetlands and impoundments, and Kertell (1996) found little difference in adult foraging behavior or provisioning of chicks for loons that fed on natural ponds or impoundments. Nest success on a study site in the Kuparuk oil field aver- aged 60% (n = 19) (Moiteret et al.1996), and nest success in the Prudhoe Bay field was 41% and 33%, respectively, for natural ponds and impoundments (Kertell 1996~. Nest suc- cess of Pacific loons on the Yukon-Kuskokwim delta in southwestern Alaska was 32% (Petersen 1979), slightly lower than that in the oil fields. Overall productivity (fledged young per nesting attempt) of Pacific loons was comparable at Prudhoe Bay to that of arctic loons in Scandinavia (Gotmark et al. 1989, Kertell 2000~. Neither loon density nor trend estimates exist for the oil fields, however, making it impossible to determine whether changes in habitat have influenced the Pacific loon population within the oil fields. Much less is known about yellow-billed loons (G. adamsii), but Alaska's North Slope, particularly the Colville River delta and the National Petroleum Reserve-Alaska, is a major breeding area for this species, which is being consid- ered for listing under the Endangered Species Act. Shorebirds Semipalmated sandpipers (Calidris upsilla), pectoral sandpipers (C. melanotos), and red-necked phalaropes (Phalaropus lobatus) are the most widespread and abundant breeding shorebirds across the North Slope, with densities exceeding 10 nests per km2 (26 nests per mi2) in the National Petroleum Reserve-Alaska (Cotter and Andres 2000~. The North Slope is a relatively important breeding area for red phalaropes (P. fulicaria) (Cotter and Andres 2000, FWS 1986), bar-tailed godwits (Limosa lapponica), stilt sandpip- ers (C. himantopus), and long-billed dowitchers (Limno- dromus scolopaceus) (Cotter and Andres 2000~. Dunlins (Calidris alpina) are locally important and were intensively studied during the 1960s near Barrow (Pitelka et al. 1974~. Buff-breasted sandpipers (Tryngites subruficollis) are not abundant, but about half of the world's population nests on the North Slope, entirely within the area of known or prob- able oil and gas resources (Audubon Alaska 2001; Gotthardt and Lanctot, FWS, unpublished material, 2002; Lanctot and Laredo 1994~. This species is also being considered for list- ing under the Endangered Species Act. Shorebird populations appear to be stable in the oil fields, except for dunlins, which have declined there and elsewhere on Alaska's North Slope (Troy 2000~. It is pos- sible that the population losses are the result of factors out- side the oil fields. Habitat declines on wintering and staging areas in Asia (Hanawa 1985, Melville 1997, Tobai 1997) could be the cause of the Alaskan declines (Troy 2000~. CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS Two mechanisms that affect birds are habitat alteration, which causes direct or indirect effects, and reduced nest suc- cess associated with predation. Direct alteration of habitat displaces individuals from locations where they might oth- erwise nest. Secondary effects, including changes in drain- age patterns, thermokarst, deposition of dust, and disturbance associated with activity on roads, can displace additional individuals. Shorebird densities are lower near roads and gravel pads than in more distant areas (Connors and Rise- brough 1979, TERA 1993a, Troy and Carpenter 1990), but densities are higher on the leeward sides of roads than else- where, suggesting that dust shadows could create conditions attractive to shorebirds (TERA 1993a). Both Meehan (1986) and TERA (1993a) estimated that 5% of shorebirds were displaced from preferred nesting areas by the direct or sec- ondary effects of oil-field facilities. The impact of such dis- placement on population dynamics is unknown, however, because potential limiting effects of nesting habitat are poorly understood on Alaska's North Slope. Attempts to as- sess tertiary effects, such as habitat fragmentation, have pro- duced contradictory results (Meehan 1986, TERA 1993a). Troy (1996) reported that semipalmated sandpiper abun- dance was correlated with nesting success two years before, suggesting that recruitment might play an important role in regulating this population in the oil fields. Few estimates of nest success for other sites in Alaska are available for com- parison. There is evidence that nesting success for other ground-nesting birds is unusually low in the oil fields (Anderson et al. 2000, Sedinger and Stickney 2000), and that, combined with Troy's (1996) results, suggests that in- creased predation in the oil fields is affecting local shorebird populations. Shorebird populations have probably been affected by the loss in food supply caused by contamination of wetlands by reserve pits (West and Snyder-Conn 1987~. West and Snyder-Conn (1987) demonstrated that invertebrate diver- sity and abundance were reduced in wetlands within 25 m (80 ft) of reserve pits. However, because reserve pits are no longer used for disposal of drilling waste and because exist- ing reserve pits are being emptied, the outlook is improved. Tuncira Swan Tundra swan (Cygnus buccinator) populations have in- creased in Alaska (Conant et al. 2000) after their over-har- vesting in the early part of the twentieth century (Banko and Mackay 1964~. The rate of increase in the Kuparuk oil field between 1988 and 1997 (Ritchie and King 2000) exceeded that in other parts of Alaska (Conant and Groves 1997~. There are caveats, however. Alaska's North Slope tundra swans, including those that inhabit the oil fields, winter on the east coast of the United States; those that breed in southwestern Alaska winter west of the Rocky Mountains (Bellrose 1980~. Thus, tundra swans in the two regions expe- rience different winter conditions. Additionally, climate
EFFECTS ON ANIMALS warming has been pronounced on the North Slope, produc- ing longer frost-free periods during the breeding season (Lachenbruch and Marshall 1986), which might have dis- proportionately benefited swans there. Thus, if there have been negative effects of oil-field development on tundra swans, they have been insufficient to prevent the rapid growth of the population during the past decade. As with other species of birds, loss of habitat could re- duce swan densities in the oil fields. Given the large territo- ries (Ritchie and King 2000) and resulting low densities of breeding swans throughout their range, however, it is un- likely that the loss of less than 5% of potential breeding habi- tat has substantially affected breeding swans in the oil fields. Disturbance associated with facilities might be more impor- tant than habitat loss, because swans are sensitive to human disturbance at considerable distances (greater than 500 m [1600 ft]) (Monda 1991~. Tundra swan broods have been reported to avoid some areas within 100-200 m (330-660 ft) of roads, although habitat use outside the breeding season did not appear to be affected by roads (Murphy and Ander- son 1993~. Ritchie and King (2000) concluded that oil-field facilities had little influence on distribution of tundra swan nests because the mean minimal distances from swan nests to structures were less than the mean minimal distances be- tween nests (Stickney et al. 1994), so territorial spacing is more important to breeding distribution than is proximity to artificial structures. Predation does not seem to have influenced nest success in the oil fields (83%) (Murphy and Anderson 1993), which was comparable to that for tundra swans nesting in Arctic National Wildlife Refuge (76%) (Monda et al. 1994~. Black Brant Nest success of black brant in the oil fields has been chronically low, ranging from 44% to 55% (Sedinger and Stickney 2000), in contrast to that in other colonies where nest success is typically near 80% (Barry 1967, Sedinger et al. 2002~. Low nest success is associated with high predator populations in the oil fields. Modeling of this population suggests that oil-field populations are not sustainable at such inadequate nest success and could represent a sink popula- tion (Sedinger and Stickney 2000~. Thus, high predator populations associated with human activity in the oil fields likely represent the greatest harm to nesting brant in the region. Black brant nesting in the oil fields are a relatively small proportion (less than 2%) of the entire breeding population for this subspecies (Sedinger et al. 1994, Sedinger and Stickney 2000), although many brant broods from the Colville River delta use the oil fields after hatching. B rant breeding in the oil fields and in the delta increased several- fold between 1982 and 1992 (Sedinger and Stickney 2000), supporting the view that the growth has been sustained by immigration from other areas. 121 13 rent nest colonially or semi-colonially (Sedinger et al. 1993) and are therefore less likely to be displaced by oil- field structures unless the facilities are placed on or immedi- ately adjacent to nesting concentrations. Facilities do not seem to have displaced nesting brant (Murphy and Anderson 1993, Stickney and Ritchie 1996~. The largest nesting con- centrations in the oil fields occur on Howe and Duck islands, 5 km (3 mi) and a few hundred meters, respectively, from the Endicott Causeway. Similarly, large numbers of brant broods use the salt marsh within 0.5 m (1.6 ft) of the Oliktok long-range radar site (Sedinger and Stickney 2000~. During nesting and brood rearing at these sites, brant responded to humans at distances of less than a few hundred meters (Murphy and Anderson 1993~. Brant also responded to 12% of vehicles that passed within 300 m (980 ft), although those responses lasted less than 5 minutes (Murphy and Anderson 1993) and likely had little effect on their nutritional status. Observations of color marked and radio-tagged brant broods provided no evidence that roads or other oil-field facilities impeded movement from nests to brood-rearing areas (Stickney 1996~. Brant goslings in the oil fields were actu- ally larger than those from the Yukon-Kuskokwim delta at the same age, implying greater abundance of food in the oil fields (Sedinger et al. 2001~. A long-term color-marking and monitoring program has allowed estimates of annual survival for adult and juvenile brant from the oil fields. The estimates show that adults from the oil fields have similar if not slightly higher survival rates than those from the delta in southwestern Alaska (Sedinger et al. 2001~. Juvenile brant from the oil fields survived the first stage of fall migration at higher rates than did those from the Yukon-Kuskokwim delta, probably because of their superior growth conditions (D. H. Ward, USGS, personal communication, 2001~. The North Slope is particularly important as a molting are for black brant. About one-third of the world's popula- tion of Pacific black brant assemble in the lakes and tundra north and east of Teshekpuk Lake to molt. During that time they are sensitive to disturbance by aircraft, especially heli- copters (Derksen et al.1982, Miller 1994, Miller et al.1994, Ward and Stehn 1989~. If industrial activity expands into this region in the form of satellite fields without permanent road links, increased air traffic is inevitable. The fact that brant fly long distances to molt in this area strongly suggests it is unusually favorable as a place to molt. This assumption is supported by analyses of the tundra vegetation in this area. Eiclers Spectacled (Somateriafischeri) and Steller's (Polysticta stelleri) eiders are currently listed as threatened under the Endangered Species Act, mainly because of their decline in excess of 90% since the 1970s on the Yukon-Kuskokwim delta in southwestern Alaska (Stehn et al.1993~. Threatened status has heightened interest in the North Slope populations,
122 but the historical record is short, and there are no data with which to compare pro- and postdevelopment populations. Spectacled eiders nest at relatively low densities on the North Slope (Ducks Unlimited 1998, Mallek and King 2000), so it is difficult to acquire sufficient censuses to make inferences. Nesting spectacled eiders do not appear to avoid oil- field structures, although nests appear to be farther from fa- cilities than are those of prebreeding spectacled eiders (Anderson et al. 2000~. Nest attendance patterns in the oil fields (Anderson et al. 2000) are comparable to those in the delta (Flint and Grand 1999), indicating that disturbance of incubating females does not reduce nest attendance in the oil fields. Nest success in the oil fields (42%) (Anderson et al. 2000), however, is substantially lower than in the delta (48%, Grand and Flint 1997; 70%, Moran 2000~. Low nest success in the oil field is primarily associated with predation (Ander- son et al.2000~. Despite the low nest success, the population in the oil fields was stable over 8 years of monitoring (1993- 2000) (Anderson et al. 2000), although the relatively short study period and the small numbers recorded (typically fewer than 10 nests) each year make it difficult to discern actual trends. Low nest success is cause for concern, however, and the local population might not be sustainable without regular . . . mm~grahon. Because common eiders (Somateria mollissima) nest predominantly on barrier islands in the Beaufort Sea they have not been close to most oil-field activities. One excep- tion was intensive operations in 1983 near Thetis Island, north of the Colville River Delta (Johnson 2000a). Nest suc- cess on Thetis Island in 1983 (81 %) was higher than in other years or at other locations on Alaska's North Slope (less than 45%), possibly associated with removal of arctic foxes from Thetis Island that year (Johnson 2000a). Numbers of common eider nests on barrier islands north of the oil fields have generally increased since 1970, possibly as a result of placement of anthropogenic debris on the islands, which ei- ders use as nesting cover (Johnson 2000a). Glaucous gulls are important predators of eider ducklings, but there are no data to evaluate the potential effects of increased glaucous gull populations in the oil fields on survival of common ei- der ducklings in coastal lagoons immediately north of the oil fields (Johnson 2000a). King eiders (S. spectabilis) have been studied for a shorter period, but there are no apparent trends in their popu- lations within the oil fields (Anderson et al. 2001~. They do not appear to avoid oil field structures (Anderson et al.2001~. Nest success in the Kuparuk oil field averaged 32% from 1993 to 2000 (Anderson et al. 2001), similar to that of other waterfowl in the oil fields, and consistent with the hypoth- esis that nest success rates are low in the oil fields. Lesser Snow Goose Like black brant, lesser snow geese (Chen caerulescens caerulescens) nest on Howe Island and Duck Island near the CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS Endicott Causeway (Johnson 2000b). As with other birds nesting in the oil fields, predation appears to be the principal negative effect of oil development. Oil-field-nesting snow geese are less than 1 % of the North American winter popula- tion (Bellrose 1980, Johnson 2000b), but the oil-field popu- lation has increased 10-fold since monitoring began in 1980 (Johnson 1994~. Snow geese typically rear broods in salt marshes east of the Endicott Causeway and in freshwater and salt marshes west of the causeway. Broods are reared much closer to the nesting area than is normal for most other snow geese, which often move 70 km (40 mi) for brood rear- ing. The broods did not change their use of brood-rearing areas after construction of the causeway (Johnson 2000b). Nest success was generally lower than for snow geese nest- ing at La Perouse Bay (mean 92%, Cooke et al.1995) and no eggs hatchedin 1991 or 1992, when arctic foxes were present on the island during the normal nest initiation period. Nest success has been low from 1991 through 2001, with com- plete failure some years (Alaska Audubon 2001~. Thus, the population on Howe Island appears to be a sink. The North Slope of the Arctic National Wildlife Refuge supports more than 60% of the Pacific population of lesser snow geese during fall premigratory staging (Robertson et al. 1997), so significant effects would accumulate if indus- trial development were to spread to that area, accompanied by increased aircraft traffic. Conclusions ancl Projections of Future Effects Because of higher predator densities, increased preda- tion on nests is the most apparent effect of oil development on birds that nest in the oil fields. Reduced nest success is sufficient in some cases to cause population declines, so the apparent stability of some oil-field populations is presum- ably the result of immigration. As industrial activity spreads into new areas, the amount of sink habitat will increase. Placement of oil-field facilities does not appear to have re- duced overall densities in the oil fields, although some shore- birds do exhibit local displacement away from facilities and roads. Of course, the direct loss of habitat caused by place- ment of gravel fill could have reduced numbers, but the small areas actually covered, combined with the low densities of breeding birds, make it impossible to measure that effect. Similar changes are to be anticipated in newly devel- oped areas, and it appears that controlling anthropogenic food sources that could enhance predator populations will be essential to minimizing effects of predation on birds. One important unknown is how the expanded use of 3-D seismic exploration will affect birds: To the degree that this activity affects vegetation, it might affect breeding birds in areas of new development. An important consideration is that new development in the foothills of the Brooks Range could impinge on raptor species' nesting and hunting habitats. Assessment of the ef- fects of human activities on breeding raptors has produced
EFFECTS ON ANIMALS mixed information (Andersen et al. 1990, England et al. 1995, Grubb and Bowerman 1997, Schueck and Marzluff 1995, Schueck et al. 2001~. Andersen et al. (1990) detected shifts in home ranges of less than 1 km in response to mili- tary training activity in southern Colorado. Schueck and col- leagues (2001), however, detected little effect on the num- ber, distribution, or behavior of raptors in the Snake River Birds of Prey National Conservation Area in response to military training activity, although they noted that raptors responded to firing of live ammunition. When effects of weather were removed from the analysis, effects of military activity on raptor distribution were further reduced (Schueck and Marzluff 1995~. England and colleagues (1995) docu- mented reduced fledging success for Swainson's hawks (Bu- teo swainsoni) in urban relative to rural areas of the Central Valley of California. That research group attributed reduced fledging success of urban nests to the distance the birds had to travel to foraging areas rather than to disturbance around nest sites. Grubb and Bowerman (1997) reported that fixed- winged aircraft elicited a response from nesting bald eagles less than 30% of the time at distances greater than 500 m (1,600 It). Bald eagles flew less than 5% of the time in re- sponse to those disturbances. Helicopters less than 500 m (1,600 ft) from nests, in contrast, elicited flight responses about 10% of the time (Grubb and Bowerman 1997~. It is difficult to evaluate the potential effect of 3-D seismic ex- ploration on prey for raptors, such as ptarmigan (Lagopus lagopus) and arctic ground squirrels. Direct effects on these populations are unlikely, but any changes in vegetation and soils over large areas could reduce habitat quality for prey, thereby reducing their populations. Given the relatively small effects of large disturbances and the location of raptor nests on cliffs and steep lakeshores and river banks, it should be possible to conduct oil development in the foothills of the Brooks Range with small effects on nesting raptors, espe- cially if aircraft and other human activities near nests are regulated. Future industrial development will likely occur in a warming climate that would probably affect timing and suc- cess of reproduction of many bird species. Tundra vegeta- tion also is likely to change. Shrubs are likely to increase at the expense of herbs, favoring some species over others. Not enough information is available at present to evaluate how likely such effects are to occur and how they will accumu- late with the effects of oil and gas activity. Finclings . Shifts in nesting distribution of shorebirds have oc- curred in response to oil-field facilities, but because of insuf- ficient information the committee cannot determine whether the displacement has affected oil-field populations. · Inadequate disposal of garbage has resulted in artifi- cially high densities of gulls, ravens, and mammalian preda- tors in the oil fields. The resulting increased predation of 123 birds' nests and young has likely made some oil-field popu- lations dependent on immigration from more productive populations elsewhere. That is, nesting areas that might have been source habitats have become sink habitats. However, population counts alone cannot reveal such effects. · Future development in the foothills of the Brooks Range could affect nesting raptors. · If development moves into the Teshekpuk Lake area of the National Petroleum Reserve-Alaska, molting water- fowl could be adversely affected, especially brant. · A major oil spill associated with shoreline or off- shore oil development would endanger molting flocks of waterfowl in nearshore lagoons. FISH The life cycles of freshwater and diadromous fishes on the North Slope are adapted to the region's long winters and low productivity (Craig 1984, 1989; Power 1997~. After break-up, fish move quickly during the brief summer into many habitats, often at great distances from the wintering area. For example, arctic cisco (Coregonus autumnalis) from the Colville River can return to spawning areas more than 600 km (370 mi) from the wintering area (Gallaway and Fechhelm 2000~. Locating a suitable wintering area at the end of the summer is critical to survival. Craig (1989) esti- mated that substantially less than 5% of stream habitat re- mains available to fish by late winter. These widespread movements and the greatly restricted area of habitat avail- able to fish in winter make many of these species highly vulnerable to the effects of oil and gas exploration and development. Nearly 40 species of fish are routinely caught during studies in freshwater and nearshore habitats of the North Slope (Bendock 1979, Cannon et al. 1987, Craig and Haldorson 1981, Fechhelm et al. 1984, LGL Alaska Res. Assoc. 1990-1996, Moulton et al. 1986~. Others are caught occasionally, but they tend to be rarer or associated with offshore marine areas. Seventeen of the frequently occurring species com- monly enter the subsistence harvest. Arctic cisco and broad whitefish (Coregonus nasus) have the highest subsistence value. An average of 18,500 kg (40,800 lb) of arctic cisco was harvested annually from the Colville River delta each fall from 1985 to 1998, with an additional 3,200-4,000 kg (7,100-8,800 lb) taken near Kaktovik (Craig 1987, Fuller and George 1997~. The broad whitefish harvest by North Slope villages is estimated to be more than 28,000 kg (62,000 lb) annually (Fuller and George 1997, Hepa et al. 1997~. Fishes along the North Slope have three principal life histories: freshwater, diadromous, or marine. Diadromous fishes move between freshwater and the sea during their lives. The term includes anadromous species, which spawn in freshwater and grow in the sea; catadromous species,
124 which do the reverse; and those species that can spend sub- stantial amounts of time in either environment, but not nec- essarily mainly to reproduce or mainly to grow. The term diadromous is applied to ciscoes, whitefishes, and Dolly Varden char (Salvelinus malma) that migrate each year be- tween freshwater and coastal habitats (Gallaway and Fech- helm 2000~. Most freshwater species spend their entire lives in rivers and lakes of the North Slope and generally avoid saline waters, although some, such as arctic grayling (Thymallus arcticus) and round whitefish (Prosopium cylindraceum), move down river to enter low-salinity estua- rine waters during early summer. Diadromous species, such as Dolly Varden char, arctic cisco, broad whitefish, and least cisco (Coregonus sardi- nellaJ, migrate each summer between upriver overwintering areas and feeding grounds in coastal waters. That group is more abundant along the Beaufort Sea coast than along the northeastern Chukchi coast, possibly because of a lack of large rivers and because of the Chukchi's less-productive coastal region (Fechhelm et al. 1984~. Most marine species inhabit deeper offshore waters and are rarely reported in the North Slope coastal zone. Notable exceptions along the Beaufort Sea coast are arctic cod, fourhorn sculpin (Myoxocephalus quadricornis), and arctic flounder (Pleuronectes glacialis), which specifically migrate into shallow, low-salinity coastal waters and estuaries dur- ing summer. Those species, along with capelin (Mallotus villosus) and Pacific herring (Clupea harengus pallasi), also dominate the fish biota along the Chukchi Sea coast (Fech- helm et al. 1984~. Diaciromous ancl Freshwater Fishes Diadromous fishes in the Beaufort Sea exist in two ma- jor population centers: the Mackenzie River system of Canada in the east and the Colville River and Arctic Coastal Plain systems of Alaska in the west (Craig 1984~. Most of the major river systems along the 600 km (370 mi) coastline between the Mackenzie and Colville rivers originate in the Brooks Range (Craig and McCart 1975~. The rivers are shal- low and provide little over-wintering habitat except for that associated with warm-water perennial springs (Craig 1989~. Dolly Varden char and arctic grayling are the two principal species that inhabit mountain streams, although lakes asso- ciated with the drainages can contain lake trout (Salvelinus namaycush), arctic char (Salvelinus alpinus), and arctic gray- ling. Ninespine sticklebacks (Pungitius pungitius) also are prevalent in drainages within the western mountain streams. Small runs of pink salmon (Oncorhynchus gorbuscha) occur in the Sagavanirktok and Colville rivers, and spawning popu- lations of chum salmon (O. keta) inhabit the Colville and Mackenzie rivers (Craig and Haldorson 1986, Moulton 2001~. The remaining salmon species consist of individuals from southern populations (Bering Sea) that are incidental visitors to the Beaufort Sea (Craig and Haldorson 1986~. CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS Three species arctic cisco, broad whitefish, and arctic gray- ling are examined here in detail. These three use the com- plete range of habitats affected by the North Slope oil and gas development, and at their various life stages they are vulnerable to the consequences of development. The few diadromous species found along coastal region of the north- east Chukchi Sea likely originate from large river systems in the southeast Chukchi Sea or along the Beaufort Sea (Fechhelm et al. 1984~. Arctic Cisco Arctic cisco in the Alaskan Beaufort Sea originate from spawning grounds in the Mackenzie River system of Canada (Gallaway et al.1983,1989~. Fry emerge by spring ice break- up in late May to early June and are swept downstream to coastal waters, where they begin feeding in the brackish waters near the Mackenzie delta. Young-of-the-year are transported away from the Mackenzie region by wind-gen- erated currents. In years with predominant easterly winds, some young-of-the-year are transported westward to Alaska by wind-driven coastal currents (Colonel! and Gallaway 1997, Fechhelm and Fissel 1988, Fechhelm and Griffiths 1990, Gallaway et al. 1983, Moulton 1989, Schmidt et al. 1991, Underwood et al. 1995~. They arrive in the Prudhoe Bay area from mid-August to mid-September. In summers with strong and persistent east winds, enhanced westward transport can carry the fish to the Colville River where they take up winter residence. After entering the Colville River, they return to the river every fall for wintering in the brack- ish portion of the delta until the onset of sexual maturity at about age 7, at which point they migrate back to the Mackenzie River to spawn (Gallaway et al. 1983~. Juvenile arctic cisco are abundant enough to support a commercial fishery in the Colville River and a subsis- tence fishery at Nuiqsut (Brower and Hepa 1998, George and Kovalsky 1986, George and Nageak 1986, Moulton 1997~. Possible Accumulation of Effects Recruitment of young arctic cisco into the Alaskan Beaufort Sea is a function of wind-generated coastal cur- rents, so facilities that interrupt the movement of fish along the coast could lead to reduced recruitment. The presence of multiple similar structures would cause effects to accumu- late. To affect recruitment, a structure would modify the coastal habitat in such a way as to hinder young arctic cisco from reaching the Colville River, the most suitable winter- ing area. The hindrance could result from modifying the coastal environment so that westward movement is delayed enough that they fail to reach the Colville River in the re- cruitment year. The available data indicate that arctic cisco recruitment has not been affected by existing causeways (NSB/SAC 1997~.
EFFECTS ON ANIMALS In an environment where heat is at a premium, the warm coastal waters are important to diadromous fishes (Craig and Haldorson 1981~. Facilities that disrupt this narrow coastal band could disrupt the coastal movements of arctic cisco and other diadromous species (Hachmeister et al. 1991, Hale et al. 1989~. Any future operations that discharge warm water could serve as attractants that would prevent fish from mov- ing to wintering areas at the proper time. The potential for effects to accumulate arises when multiple facilities affect the same populations of fish. Broacl Whitefish Broad whitefish are common in lakes and streams of the Arctic Coastal Plain, most abundantly in large rivers, such as the Colville, Ikpikpuk, and Chipp rivers, that have deep, low- velocity channels and a multitude of connected lakes. They are also in the Sagavanirktok River, but its steeper channel gradient and low number of connected lakes limit that popu- lation. During summer, some broad whitefish enter small tundra streams. The fish use a variety of habitats through their life cycle. Spawning is in deep portions of large rivers in the fall. In the Mackenzie River in Canada, broad whitefish spawn in the lower river just upstream of marine influence. Similarly, the anadromous population in the Colville River spawns in the main river upstream of the delta. Bendock and Burr (1986) identified a prespawning migration in August. During the spring flood, age-O and juvenile broad whitefish enter a vari- ety of available habitats, including seasonally flooded lakes, lakes connected to stream systems, river channels, and coastal areas. Fish that use perched lakes remain in the lakes until they reach maturity, then return to the river in the spring of the year in which they will spawn. Broad whitefish that do not enter perched lakes either enter the coastal region and adjacent small drainages to feed or remain within the river system to feed in low-velocity channels, tapped lakes, or drainage lakes. In fall, they move out of the shallow feeding areas and return to the deep wintering areas in the main river or lakes. Fish from the Sagavanirktok River population move through the Prudhoe Bay coastal region and enter lakes at- tached to small drainage systems (Morris 2000~. During summer, broad whitefish are distributed throughout the drainages and coastal plain water bodies. The highest abundance in coastal marine waters is near river del- tas (Furniss 1975, Griffiths et al.1983, Moulton and Fawcett 1984, Moulton et al. 1986, Schmidt et al. 1983), although large fish move at least between the Colville River and Prudhoe Bay region. When they are in coastal waters, broad whitefish show a strong preference for nearshore habitats, appearing only rarely offshore or near barrier islands (Craig and Haldorson 1981, Moulton et al. 1986~. The main overwintering areas in the Colville River are upstream from the Itkillik River. Most broad whitefish leave the delta after ice forms and move upstream beyond the in- 125 fluence of salt water. In the Sagavanirktok River, wintering areas have been identified in both the east and west channels within 20 km (12 mi) of the river mouth (Morris 2000~. Possible Accumulation of Effects Because of the wide range of habitats used by broad whitefish populations in the Sagavanirktok and Colville riv- ers, the potential for effects to accumulate is high. They use nearly all stream systems between Barrow and the Saga- vanirktok River, they enter a large number of lakes associ- ated with the streams, and they move widely along the coast, ranging as far east as the Canning River. As a result, they are vulnerable to facilities that change the distribution of fresh- water and the coastal nearshore band. Because many rear in lakes, they are vulnerable to excessive water withdrawal and the introduction of contaminants. Arctic Grayling Arctic grayling is the second-most-widespread freshwa- ter fish on the North Slope, after ninespine stickleback. It occurs in most stream systems and in many lakes (Moulton and George 2000~. Grayling typically overwinter in deep areas within larger rivers the Colville, Kuparuk, Saga- vanirktok, and Canning. Wintering areas are limited or non- existent in smaller tundra streams (Hemming 1993~. During or after ice break-up, adult grayling move into tributary streams for spawning. Streams with sand or gravel substrates seem to be most heavily used. After spawning, adults disperse to summer feeding areas, moving downstream in the tributary to feed on drift insects, moving into lakes, or returning to the main river. Grayling embryos hatch after about three weeks. Young-of- the-year (age-O) grayling feed in tributary streams until late summer, then move into the main river for wintering. Juve- niles, which do not participate in spawning migrations, move in spring from wintering areas into small streams, lakes, or shallow areas within the main river to find suitable feeding areas. As with most arctic freshwater fish, arctic grayling are strongly limited in abundance by the availability of winter- ing habitat. Many streams across the Arctic Coastal Plain are devoid of grayling or contain only a few juveniles because they are far from suitable wintering areas and lack dispersal routes that allow free passage during both spring and late summer. Possible Accumulation of Effects Disruptions to flow patterns that affect arctic grayling movements can affect survival, and the proliferation of roads and culverts across wetlands and streams creates the poten- tial for effects to accumulate. Delays in the upstream spawn- ing migration were common in the early stages of oil-field
126 development, when culverts were too small to handle break- up flows. Road-crossing and culvert designs now include fish passages, so effects should be less than in the early years of development. The distribution of arctic grayling has expanded because of habitat alterations in the oil-field region. Some of the large, deep gravel pits excavated for oil-field construction material filled with water after abandonment to form large artificial lakes that provide abundant wintering habitat. Hem- ming (1988) reported that a mine site connected to the Sagavanirktok River contained 88 times more water than the largest wintering areas reported within the river itself. Two of the deep gravel pits were connected to small tundra streams that appeared to contain suitable spawning and rear- ing habitat but lacked wintering areas. Arctic grayling of various ages were introduced over several years and eventu- ally developed reproducing populations (Hemming 1995~. The cumulative effect of these large gravel pits is to increase the available freshwater wintering area. It is not known whether the amount of habitat added by the gravel pits out- weighs possible loss of habitat attributable to hampered mi- gration caused by roads and pads, but with the recently in- creased attention to structural design it is likely that most of the migration problems have been solved. There is a reasonable amount of information on fish- passage problems and ways to mitigate them (Ott 1993~. The rehabilitation and success of habitat restoration in many of the North Slope gravel pits are well documented (Hemming 1988, 1993, 1995; Hemming et al. 1989~. Effects in Freshwater Systems Effects in streams and lakes can accumulate through disruption of drainage patterns combined with water with- drawal and contamination. Hershey and colleagues (1999) demonstrated that the landscape controls biological interac- tions in lakes through facilitating or limiting fish dispersal. Activities that affect dispersal through alterations to drain- age patterns can ultimately affect the assemblage of fishes in different habitats. Water withdrawals affect the amount of water present during winter, which can affect fish survival. Drainage Patterns Drainage patterns are altered by the construction of roads or pads in or across wetlands or drainage areas. To date, 2,338 ha (5,777 acres) of gravel pads, including more than 875 km (544 mi) of roadways, have been constructed in association with oil-field development on the North Slope (Chapter 4~. Much of the gravel fill has been in wetlands where drainage has been blocked by road construction. Dur- ing spring ice break-up, there is substantial flow across ex- pansive wetlands into lakes and streams. When long stretches of gravel road interrupt flow, the difference in water surface elevation from one side of the pad to the other can produce CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS high-velocity water flow in the cross-pad drainage structures, usually culverts, that can inhibit upstream fish movements and delay migration to various summer habitats. The delays are particularly problematic for arctic grayling, which spawn shortly after break-up and often undertake long, rapid migra- tions from wintering areas to spawning sites. An opposite effect can occur in mid- to late summer when stream flow is low. Fish that disperse during or after break-up must leave small drainages and shallow lakes to reach wintering areas before those waters freeze because there are often limited or no opportunities for overwintering within the habitats used for summer feeding. Fish that can- not leave will freeze. An inadequate number or improper placing of culverts or modifications to the stream bed can cause flow to go below the surface or to be spread too shal- low to allow downstream movement when flow levels are reduced in late summer. Large quantities of gravel have been used to construct the oil-field infrastructure. In the early period of develop- ment and pipeline construction, much of the gravel was ob- tained from gravel deposits within floodplains. But concerns arising from this practice prompted the FWS to study the effects of floodplain gravel mining on the floodplains physi- cal and biotic processes (Woodward-Clyde Consultants 1980~. The study identified numerous examples of habitat modification, including increased channel braiding, loss of wintering areas, spreading of flow, and restriction of fish movements, including mortality caused by stranding. The study also set forth guidelines for gravel mining that mini- mize floodplain damage (Joyce et al. 1980~. In response to agency concerns, and results of the FWS study, new gravel mines were primarily in upland sites during the 1980s. Some of these were flooded when mining ceased and used as reser- vations, with the long-term goal of establishing aquatic habi- tat. Recently, some new mines have been in floodplains, again following established guidelines. Water Withdrawal Use of freshwater has increased in recent years because of expanded oil-field development and increased explora- tion. In the early years of exploration, water was obtained from any source, including rivers during winter. Bendock (1976, as cited in Winters et al. 1988) documented water withdrawals from the Sagavanirktok River that depleted water in wintering areas and increased mortality to fish in the area. Much of the water needed in the established oil fields is now obtained from reservoirs that are replenished with runoff during spring ice break-up; most of the water used in exploration is taken from lakes. Ice thickness has a great influence on the distribution of fish in lakes across the Arctic Coastal Plain. Most lakes in the existing development area between the Colville and Sagavanirktok rivers are less than 2 m (6.5 ft) deep, few fish are present, and effects have been minimal. As development
EFFECTS ON ANIMALS spreads into regions with deeper lakes, such as the Colville delta and the eastern part the National Petroleum Reserve- Alaska, there is greater potential for having fish populations within lakes. Under current Alaska Department of Fish and Game (ADF&G) policy, water withdrawals from fish-bear- ing lakes are limited to 15% of the estimated minimum win- ter water volume. This policy was adopted to allow some water use while preserving most of the water for wintering fish, and the criterion was set arbitrarily because there were no data to support a different withdrawal volume. Fish popu- lations in lakes subjected to this maximum allowable with- drawal appear to be unaffected, but data on consequences are limited, and there has been no research to determine the effects of withdrawals on populations of invertebrates in the lakes or on vertebrate food supplies. The current practice for ice road construction is to per- mit withdrawals from a large number of lakes along a de- sired route, then to allow the ice road contractor to draw from the nearest suitable lake. This allows for maximum construction flexibility, but it complicates the tracking of withdrawal volumes: Much more water is permitted for withdrawal than is used. Between 1998 and 2001, for ex- ample, Phillips Alaska obtained annual permits for with- drawals of more than 8.3 billion L (2.2 billion gal), but used less than 908 million L (240 million gal) in any given year (Table 8-2~. For lakes that do not support wintering fish, there is essentially no current regulation of winter water withdraw- als, and the amount estimated to be present during summer is typically set as the withdrawal limit. Because ice thickness grows to 1.2-1.5 m (4-5 ft) by the time withdrawals are needed in January through March, there is substantially less water available than the permitted amount, thus the full amount is not really available for use and the actual with- drawal is considerably less than that permitted. This practice essentially allows withdrawal of all remaining unfrozen wa- ter in the lake at the time of withdrawal. The effects of such withdrawals on lake flora and fauna have not been analyzed. Effects on invertebrates are not likely to be significant be- cause during winter most invertebrates inhabiting shallow lakes are in freeze-tolerant resting stages. The potential ef- fects of reduced water levels on vegetation and waterfowl nesting or feeding have not been evaluated. TABLE 8-2 Phillips Alaska Water Permits Winter Year Lakes Permitted Withdrawal Limit (million L) Total Used (million L) Percentage Used 1998-1999 1999-2000 2000-2001 26 41 24 8,477.4 8,468.7 8,944.1 771.1 886.2 344.5 9.1 10.5 3.9 SOURCE: Phillips Alaska, Inc., data files submitted to Alaska Department of Natural Resources. 127 An additional issue associated with water withdrawals from fish-bearing lakes is the potential to remove fish during pumping. In recent years, as construction of ice roads has increased in the vicinity of Nuiqsut, residents have reported finding fish frozen into the roads. Contracts issued for ice road construction specify that water is to be screened to avoid removing fish, but contractors sometimes fail to install screens. In some cases, sampling to identify the presence of fish before water withdrawal used gear that was not appro- priate for detecting smaller species, such as ninespine stick- leback and Alaska blackfish (Dallia pectoralis). The prob- lem can be aggravated when lighted shacks are placed over the hole from which water is withdrawn. Ninespine stickle- back, in particular, are drawn to the light, then are sucked up with the water and spread on the road. Procedures have been adopted recently to prevent taking fish with water for road construction. Seismic Effects When seismic exploration was conducted with explo- sives, there was a great potential for harming fish that were exposed to large, rapid changes in ambient pressure. The advent of vibrating equipment has reduced concern, because the energy it generates is much less than that generated by explosives. The ADF&G blasting standards require that the instantaneous change in pressure resulting from any explo- sion must remain below 0.02 megapascals (MPa, 2.7 psi). Results of a recent field test involving vibrators on ice, over water, indicate that peak pressure changes below a vibrator (under 1.2 m [4 ft] of ice) can be as low as 0.01 MPa (1.57 psi). In addition, the energy velocity appears to be many times slower than velocities known to harm fish. Peak sound pressure levels associated with vibroseis exploration, calcu- lated at 7.3 m (24 ft) from the source, appear to be about 12 dB lower than sound pressure levels associated with airguns. When converted to energy, the vibroseis machines transfer many times less energy to the water than do airgun arrays (W. Morris, ADF&G, personal communication, 2002~. The effects of summertime seismic exploration with airguns on coastal and marine fish in the Beaufort Sea have not been investigated. Coastal Development Coastal development that poses the greatest risk of caus- ing effects that accumulate in nearshore habitats includes facilities that change physical conditions that are important to nearshore biota. Such structures include causeways that modify water temperature and salinity. Two major causeways have been built into the nearshore region to support oil-field activities (Table 8-3~. The Prudhoe Bay West Dock was built in the winter of 1974-1975 primar- ily to support off-loading of large modules used to develop the field; it was modified in 1981 to support the intake struc-
128 ture for the Prudhoe Bay waterflood facility to supply water needed for injection into the oil reservoirs. The causeway runs from the east end of Simpson Lagoon to the west en- trance to Prudhoe Bay. The second major causeway, in the middle of the Sagavanirktok River delta, was built to sup- port facilities for the Endicott oil field. Accumulation of effects is a concern when multiple causeways affect the same fish population. The migratory stocks found along the Beaufort Sea coast are likely to en- counter multiple causeways during their annual summer feeding movements. From the late 1970s to late 1980s, there was substantial concern over the potential effects of the two long causeways to migrating fishes, especially for the integ- rity of the nearshore band of relatively warm, low-salinity coastal water that is used by migrating fish (Craig 1984~. Causeways built perpendicular to shore disrupt the east-west flow of the coastal currents, and that can alter fish move- ments within the band. Permits issued by the U.S. Army Corps of Engineers and the North Slope Borough for cause- way construction included stipulations for monitoring the effects of the causeway on fish movements and habitat, among other issues. Initial monitoring studied the West Dock Causeway between 1981 and 1984 and then the West Dock and Endicott causeways between 1985 and 1987. In 1988, the U.S. Army Corps of Engineers concluded that signifi- cant harm to habitat had been demonstrated and that further monitoring for effects on fish populations was not required (Hachmeister et al. 1991~. Those effects, as summarized Ross (1988), included degradation of habitat quality in the nearshore region, alteration to fish movements and fish use of the Prudhoe Bay area, and changes to fish community structure. The North Slope Borough, with the advice of its Scien- tific Advisory Committee, determined that the findings were not supported by the existing data, however, and decided to continue the causeway-monitoring program under its per- mitting authority. The effects described by Ross (1988) were TABLE 8-3 Causeway Construction, Nearshore Beaufort Sea Facility Length of Year Fill (m) Notes East Dock West Dock Initial dock Emergency extension Waterflood extension Breach retrofit Endicott Initial causeway Breaches (2) Breach retrofit pre- 1974 1974-1975 1975-1976 1981 1996 1985 8,000 1986 -60, -150 1994 -200 350 1,340 1,524 1,125 -18 m breach -200 at 1,520-1,720 m SOURCE: U.S. Army Corps of Engineers permitting documents arid cause- way monitoring reports. CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS used to frame a set of hypotheses that were then used to design the monitoring investigations. The North Slope Bor- ough monitoring program focused its investigations on four . . main Issues: · effects of causeway-induced changes in circulation and hydrography on the migration of young-of-the-year arc- tic cisco from Canada to the Colville River, · effects of causeway-induced changes in circulation and hydrography on the nearshore migration corridor used by most species of diadromous fish, · changes to temperature and salinity of the nearshore habitat and ramifications of those changes to the population of broad whitefish inhabiting the Sagavanirktok River, and · effects of causeway-induced changes to fish and fish habitat on the fisheries that harvest arctic and least cisco in the Colville River. The North Slope Borough's program showed that the causeways, particularly the West Dock Causeway, interfere most notably with the eastward movement of juvenile least ciscoes and humpback whitefish moving from the Colville River into the Prudhoe Bay area during early summer (Fechhelm 1999, Fechhelm et al. 1989, Gallaway and Fechhelm 2000, Moulton et al.1986~. Juvenile Dolly Varden char also might be affected (Hachmeister et al. 1991~. The movement of young-of-the-year arctic cisco from the Mackenzie River into the Alaskan Beaufort Sea region did not appear to be affected by the causeways (NSB/SAC 1997~. Retrofitting of breaches in both causeways in 1994 and 1996 appears to have reduced the effect of the interference to least cisco and humpback whitefish (Coregonus pidschian) mi- grations (Fechhelm 1999~. The causeway studies revealed that, when wind is from the east, a wake eddy forms on the west side of the cause- ways that allows cold, high-salinity water to reach the sur- face (Colonel! and Niedoroda 1990, Gallaway and Fechhelm 2000~. That cell of cold water on the west side of West Dock is the mechanism that most likely impedes fish movements. Because the wake eddy on the west side of Endicott Cause- way is offshore of the Sagavanirktok delta, its effects on fish movements are less pronounced. Various researchers have noted that the density of epibenthic fauna (mysids and am- phipods), which constitute the main foods of diadromous fish and sea ducks, was particularly high along the west side of West Dock (Feder and McGee 1982, Moulton et al.1986, Robertson 1991), perhaps as a result of the wake-eddy effect in the lee of the causeway under east winds. Gallaway and Fechhelm (2000) concluded that fish populations in the region appear to be fluctuating in response to naturally occurring physical phenomena. Effects of the existing causeways have been at least partially mitigated with retrofitted breaches. In addition to the causeways, large intake pipes are used to withdraw water from the nearshore region. The Prudhoe
EFFECTS ON ANIMALS Bay waterflood facility, constructed in 1981, can supply 350 million L (92.4 million gal) of seawater per day (4.07 m3/s [5.32 yd3/s]), with an estimated 2.55 km3 (0.61 mi3) to be used over 20 years (USACE 1980~. There are also seawater intakes at Endicott (44 million L [11.6 million gal] per day) and Kuparuk (95 million L [25.2 million gal] per day). Moni- toring of the intakes and marine bypass systems was con- ducted after start-up for the Prudhoe Bay and Kuparuk wa- terflood facilities from 1984 to 1987 to assess entrainment and impingement (Dames and Moore 1985-1988~. Fish were rarely observed during the monitoring studies, and most of those that entered the system passed successfully. However, approximately 1.5 million fish larvae of 9 species were esti- mated to have been entrained in the Prudhoe Bay facility in 1985. The intakes were judged to perform as designed and predicted, and monitoring was discontinued after 1987. Beaufort Sea causeways are among the most intensively studied anywhere. From 1978 to 1997, the West Dock and Endicott causeways were monitored for changes to physical oceanography, coastal processes, sedimentation patterns, fish populations and movements, fish growth, subsistence landings, fish-species diversity, benthic invertebrate popula- tions, epifaunal populations, river hydrology, vegetation, and bird habitat use. Annual reports of the monitoring efforts were produced that summarized the results of the annual in- vestigations. A decade of investigations on oceanographic changes related to the two major causeways was summa- rized by Colonell and Niedoroda (1990), Hachmeister and colleagues (1991), Hale and colleagues (1989), and Nie- doroda and Colonell (1990~. The spatial extent of the causeways is relatively limited; the two receiving most of the attention are on either side of Prudhoe Bay. Some of the fish that encounter the causeways, including arctic cisco, however, move between the Colville and Mackenzie rivers at least twice during their lifespan. Some of the least cisco, humpback whitefish, and broad whitefish move between the Colville and Canning rivers for the summer feeding (Fechhelm et al. 2000, Griffiths et al. 2002~. The effects of causeways in this region on those fish population could accumulate if the breach retrofits have not completely eliminated movement and habitat changes. Any effects resulting from the causeways will exist until the struc- tures are removed, or are made porous enough that fish movements are unaffected. Future Scenario The potential effects on freshwater systems have be- come clear during the development of the existing oil fields, so those effects probably will be addressed during the design and permitting of new fields and field expansions. The prob- ability for serious effects is low, assuming due diligence by the responsible resource agencies. There will be new chal- lenges, however, as exploration and development practices change. For example, exploration to the east and south will 129 be hampered by the reduced availability of water during winter. In addition, because those areas have more hills and valleys, the grades for roads will be more extreme. The cur- rent technology based on ice road access is not likely to be feasible in those areas. Similarly, current field development depends on a ready supply of gravel for road and pad con- struction. Development of fields in the National Petroleum Reserve-Alaska, where gravel is scarce, will need to rely on other materials for road and pad construction, and the conse- quences associated with alternative materials will need to be examined. Future coastal developments could include more docks and causeways to transport structures or oil to shore. Given the adversarial history of causeway impact assessment, con- struction of new causeways probably will be approached carefully with substantial scrutiny by regulatory agencies. Each potential causeway site along the Beaufort Sea coast is unique with respect to currents and the ways that fish use the region. Therefore, the design constraints on each proposed causeway will be site-specific. Nonetheless, long solid-fill causeways are likely to be problematic and therefore are unlikely to be permitted. New docks are likely to be rela- tively small bulkhead structures near water deep enough to allow barges to approach the shore, so as to minimize the offshore reach of the docks. Where shallow water requires a longer reach, docks will likely have numerous large bridged beaches that allow freer flow of water and minimize the im- pediments to fish movements. Finclings · During the early years of development, gravel min- ing for roads and pads often interrupted both ice-sheet flow and stream flows, and hence fish movement. The permitting process and the regulatory environment for protecting fish have improved over time and are generally effective. Proper construction and placement of bridges and culverts have greatly reduced effects but have not eliminated them. · Guidelines for gravel mining and subsequent habitat rehabilitation or enhancement in and near active floodplains have been developed. Since 1989, arctic grayling have been introduced to several of the deep gravel pits that now pro- vide productive fish habitat. One effect of these large gravel pits is to increase the available freshwater wintering area; it is likely that the tradeoff is positive and the negative effects are less than would have occurred if the gravel had been taken from active floodplains. · The energy produced by vibration equipment used to acquire seismic data is not an issue because the vibrations are below threshold known to affect fish in streams and lakes crossed during the seismic investigations. The potential ef- fects of airguns on Beaufort Sea fish have not been studied. · Because of a lack of information it is not possible to determine whether biota associated with North Slope lakes are protected by regulations that cap water withdrawal from lakes.
130 · Existing causeways near Prudhoe Bay do not affect the westward recruitment of arctic cisco into the Colville River and associated rearing areas. Blockage of young least cisco and whitefishes moving eastward from Colville to Prudhoe Bay was demonstrated under certain wind condi- tions in some years at the West Dock Causeway. This block- age has been reduced by the breach retrofit installed in 1996. · The effectiveness of breach design for existing or new causeways has not been resolved. Breaches are effec- tive, but there is more to be learned about the best or most appropriate design and placement of them. The North Slope Borough's Scientific Advisory Committee recommends that breaches be required in any causeway that extends across the nearshore zone, which seems to be appropriate. · Seawater intakes have been designed to prevent en- trainment and impingement of fishes. · Large-scale industrial development could harm widely distributed fish, such as grayling, arctic cisco, broad whitefish, and other species in other areas, by interfering with their migration patterns or their overwintering habitat. Recommenclations · Monitoring of rehabilitated deep gravel pits should continue to evaluate the long-term viability of these sites as aquatic habitat. · The current baseline of 15% of minimum winter wa- ter volume that is allowed to be removed from fish-bearing lakes should be evaluated to determine the degree to which that criterion prevents loss of fish and invertebrates. · An initial study of the effects of withdrawing water from lakes that have no fish should assess the degree to which current water use affects other biota associated with these water bodies. OTHER MARINE ORGANISMS Coastal developments that pose the greatest risk of ac- cumulation of effects to nearshore habitats include industrial structures that change the physical conditions that are im- portant to nearshore biota, especially causeways that alter water temperature and salinity. Effects of Oil on Marine Plankton and Benthic Organisms The degree to which surface oil spills affect benthic communities depends on many factors, including the weather at the time of the spill, the biotic composition of the commu- nities and their sensitivity to oil, and how deep they are (NRC 2003~. Oils produced on the North Slope rise to the surface rather than sinking to the sea floor. Although surface slicks undergo some natural dispersion, the amount of oil reaching benthic organisms is less than one part per million (Humphrey et al. 1987, McAuliffe et al. 1981~. Shallow benthic communities are vulnerable if oil strands on shore- CUMULATIVE EFFECTS OF ALASKA NORTH SLOPE OIL AND GAS lines and is mobilized into the nearshore subtidal zone. Sometimes cleanup actually mobilizes oil to cause fairly high concentrations in nearshore subtidal areas. If there is a high load of suspended sediments in nearshore waters, oil can be adsorbed onto particles and be deposited in the nearshore subtidal area where it affects epibenthic organisms. Subsur- face spills from pipelines released over extended periods could affect benthic communities close to the release. Epibenthos and infauna are usually not abundant in very nearshore waters in the Beaufort Sea. Boulder patch com- munities are in deeper water and are only likely to be af- fected if a subsurface spill occurs in the immediate vicinity. If chemical dispersants are used, short-term exposure to fairly high concentrations of dispersed oil is possible. Short- term exposure to dispersed oil (from a single surface spill) is not likely to cause mortalities of the benthos. Mortalities could be caused from a prolonged surface leak that is repeat- edly treated. Recovery of benthic epifauna is likely to be more rapid than is recovery of infauna. Recovery of boulder patch communities would probably take several years (Mar- tin 1986~. Oil spills on or under spring ice would diminish primary production either as a result of toxic effects or because the oil would block light that passes though the ice sheet (Schell et al. 1982~. Some species of phytoplankton are more sensitive to oil than are others (NRC 2003~. They can be affected by a sur- face oil slick or if dispersants are used and more oil enters the water column. The affected standing stock and primary production return to pre-spill conditions rapidly through natural transport of organisms from surrounding areas and rapid reproduction of these populations (Trudel 1986a). Fish larvae and eggs can be harmed by spilled oil, and oil can be ingested by higher trophic-level organisms with prey or as a result of prey contamination (NRC 2003~. Thus, the effects of spills on phytoplankton communities generally are local- ized and short lived enough so that recovery occurs before effects accumulate. Many zooplankton species, especially as larvae, are sen- sitive to oil. Studies of zooplankton have followed several oil spills, and localized, short-lived effects have been de- tected. There are seldom changes in biomass, however, be- cause of high reproduction rates and rapid recruitment from other areas (Trudel 1986b). Effects on Biological Processes ancl Marine Communities Studies of the Boulder Patch indicate that development of its kelp-community depends on four factors: There must be a hard substrate for attachment of algae and associated invertebrate fauna. There must be free (unfrozen) water un- der the winter ice canopy and protection from extensive ice- gouging and reworking at the bottom. There must be an ero- sional rather than depositional sedimentary environment (Coastal Frontiers Corporation and LGL Ecological Re-
EFFECTS ON ANIMALS search Associates, Inc.1998; Dunton et al.1982~. Those fac- tors can exist in the vicinity of both natural and anthropo- genic hard substrates. As part of the Endicott environmental monitoring pro- gram, studies were conducted to measure long-term coloni- zation of bare boulders placed at sites in the Stefansson Sound Boulder Patch. Colonization initially was slow, being negligible (Martin et al.1988) or sparse after 3 years (Dunton et al.1982~. Five to six years were required before full colo- nization was achieved (Martin and Gallaway 1994~. The slow appearance of colonizing organisms and the presence of uncommon species led Martin and Gallaway (1994) to suggest that Boulder Patch species disperse as relatively long-lived, slow-growing larvae. Species that fail to colo- nize could have a nonmotile dispersal stage or otherwise be limited in ability to disperse. After 2 years in Stefansson Sound at drill island BF-37, red algae, particularly Phyllophora truncata and Phycodrys rubens, and one animal, a small hydroid, had colonized gravel-filled bags (Toimil and Dunton 1983~. No organisms were observed on the loose gravel at the base of BF-37. Dur- ing inspections in 1994 and 1996 of gravel-filled bags and concrete mats placed as protective armor on Tern and Northstar exploratory drill islands, divers reported algae, worms, and soft coral (Craig Leidersdorf, Coastal Frontiers Corporation, personal communication cited in Wilson 2001a). A 1998 survey reported algae about 2 m (6.5 ft) long consisting of two distinct blades, probably representing 2 years growth, attached to coarse gravel (3-5 cm [1.2-2 ink) lying near the toe at 6 m (20 ft) on Tern Island's western slope (C. Leidersdorf, Coastal Frontiers Corporation, per- sonal communication cited in Wilson 2001a). In the Stefans- son Sound area, algae of this size likely would have been kelp, and those with distinct blades likely would have been Laminaria. Leidersdorf believed the plants colonized the gravel at the base of the island (Wilson 2001a). Laminaria solidungula and L. saccharine attached to coarse gravel have been collected along the eastern shore of 131 the Endicott Causeway after heavy easterly storms. Those plants with attached gravel were presumably moved west- ward along the bottom by surge and wave action created by storm winds and deposited along the causeway shoreline (Busdosh et al. 1985~. It is possible that the kelp at the base of Tern Island were moved along the seabed by westerly storm conditions and deposited there. Finclings · Other than those caused by permitted discharges and physical alterations or addition of structures, there have been few measurable effects on marine invertebrate communities from oil exploration and production operations on the North Slope. · Hard substrates added to the marine environment in the form of causeways and artificial islands have been colo- nized slowly by benthic invertebrates. · The Boulder Patch community has not been affected by oil operations. · Monitoring is frequently required as a condition of discharge permits to ensure that discharges do not exceed water quality standards, are not toxic to marine organisms, and do not degrade water quality or pose a threat to human health. Most of the records of the monitoring programs are retained by the principal permitting agency, the U.S. Envi- ronmental Protection Agency, and are not readily available. Records also are kept by individual operators, but they are not summarized, and few annual reports are available. · Oil operations have not had measurable population effects on epibenthic invertebrates, the sessile invertebrates of the Boulder Patch communities. The epontic communi- ties under the ice have not been specifically studied, but it is unlikely that operations have affected them. · The committee found no data showing that dis- charges to the Beaufort Sea have had effects on biota. The trend is toward using disposal wells instead of discharging wastes directly to the ocean.