Developing a Research and Restoration Plan for Arctic-Yukon-Kuskokwim (Western Alaska) Salmon (2005) / Chapter Skim
Currently Skimming:
3 Historical and Recent Arctic-Yukon- Kuskokwim Research
3 Historical and Recent Arctic-Yukon- Kuskokwim Research
Pages 38-130
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From page 38... ...
It ends with a discussion of the importance of including traditional ecological knowledge in research on AYK salmon, along with strategies for achieving that goal. We have attempted to identify questions of most interest to scientists and stakeholders.
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. The environment of AYK salmon is changing, possibly due to warming and associated climate variations that are occurring throughout the Bering Sea and Alaska.
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Climate and Climate Change Before delving into the impacts climate change may have on AYK salmon populations, we sought to understand what climate change means and to identify factors that cause changes. This allows us to define both the spatial and the temporal scales of climate change and the pathways through which climate change influences biota, and AYK salmon in particular.
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Changes in cloud cover cause fluctuations in net surface solar radiation and outgoing long-wave radiation. Over the coastal waters where AYK salmon smolts enter the marine environment, latitudinal changes in net radiation could cause differences in smolt and juvenile habitat.
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2001) , and a crucial point for AYK salmon is that the warming may be amplified in polar regions (Moritz et al.
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(2003) for the eastern Bering Sea to include additional physical features such as sea ice, cloud cover, and precipitation.
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AYK salmon both through its impact on the nutrient-phytoplanktonzooplankton sequence (bottom-up) , which supplies prey, or by changing the zoogeographical boundaries for predators (top-down)
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. Salmon smolts and juveniles from the Kuskokwim River, and to a lesser degree those from the Yukon River and Norton Sound, likely occur in the waters where dynamics of the OCH apply.
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. Features of the Environment of AYK Salmon We begin our discussion of the AYK salmon environments with a discussion of the coupling of the ocean and atmosphere.
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. One way the AO influences the AYK salmon's environment is through its effect on the maiand
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Several atmospheric and oceanic phenomena influence the habitat for AYK salmon, and the responses in biota are complex. For example, the phas
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Because of this, the impact of climate change on AYK salmon is unlikely to be systematic and repetitive; the response likely varies from one regime shift to another. Changes in sea ice (Figure 3-4)
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. Circulation in the marine environment of AYK salmon is known (Schumacher and Stabeno 1998, Stabeno et al.
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. Changes in the position and volume of the Yukon River plume could have a profound impact on the geophysical environment of Norton Sound.
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Other climate models will show different results depending on the formulation and extent of the mathematics used to represent processes that dictate flow of energy through the coupled atmosphere-sea-land system. In the mid-1990s, a group of scientists well versed in atmospheric and oceanic phenomena of the North Pacific and the Bering Sea outlined the most likely impacts of global warming on this region (US GLOBEC 1996, Schumacher and Alexander 1999)
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Research Questions The following questions arise from our present lack of knowledge and analyses of the critical questions. They provide topics for research regarding the impact of climate change on AYK salmon.
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POPULATION STRUCTURE AND LIFE CYCLE OF AYK SALMON Population Genetics of AYK Salmon It is important to identify the various salmon stocks in the AYK region because they might have similar or different responses to abiotic factors and fishing. Genetic analysis is a promising method for distin
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and Canadian fall chum salmon in the Yukon River. For Chinook salmon, lower and upper river populations can be distinguished in the Yukon River but not in the Kuskokwim River.
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. When different local populations mix in the ocean or as they return to their natal spawning habitats, they will be subject to common mortality factors, even though the local populations exhibit different vulnerabilities.
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Metapopulation Structure All five North American species of Pacific salmon are found in the AYK region1, although more is known about chum in this region than the other species. In other regions, these five species are thought to form metapopulations where local populations are largely isolated in a stepping-stone type model due to the high degree of natal homing and subsequent reproductive isolation (Rieman and Dunham 2000, Jones in press)
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As a mixed stock, different local populations respond differently to this fishing mortality, and the effect on local populations and their persistence is unknown. Twenty-nine populations of Chinook salmon have been identified in the southeastern Alaska and AYK region.
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Finally, genetic information on sockeye salmon in the AYK region is even more limited, and certainly insufficient to determine population structure. Throughout their range, efforts are being made to restore lost salmon populations and to revitalize those populations in decline.
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Within this conceptual framework the following research questions are of greatest concern: · Can genetically distinct breeding populations of the five species of salmon in the AYK region be identified? Only a refined analysis of chum and increased sampling of Chinook salmon might be needed, while more extensive analysis throughout the range for coho, pink, and sockeye salmon must be undertaken.
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ECOLOGICAL INTERACTIONS OF AYK SALMON Because of their life history, salmon are enmeshed in food webs across multiple habitats, from freshwater streams to the open ocean of the North Pacific and back again. This section, organized by habitat, summarizes ecological interactions that impinge on salmon and emphasizes ongoing research on AYK populations.
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There is a dam at Whitehorse, Yukon Territory, on the main stem of the Yukon River, approximately 3,060 km from its mouth. Interestingly, those changes occurred primarily at the beginning of the twentieth century, well before the recent AYK salmon declines.
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Any recent variance in salmon populations is not likely the result of instream habitat loss or degradation. Feeding Interactions The feeding ecology of the five species of AYK salmon in freshwater and estuarine habitats influences the growth, survival, and abundance of salmon.
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and presumably do so when they co-occur in estuaries. Although the information on the use of estuarine or brackish habitats in the AYK region is scant, what is known about the ecology of pink and chum salmon elsewhere suggests these habitats may provide an important feeding area.
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Lake Becharof, Alaska, and other lake systems where growth is density independent may be examples. Competition from other species also may influence sockeye salmon dynamics.
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Because of the long stream residence of coho, they are particularly sensitive to variation in water temperature and stream discharge. Stream temperatures in coho streams in the AYK region are typically cool, especially since coho spawn and rear in spring-fed systems in the interior, so warming is unlikely to be a concern for rearing fish.
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Impact of Disease Ichthyophonus is a parasitic protist found in fishes around the world. However, in the AYK region, the disease it causes has been identified only in Chinook salmon.
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Environmental and other forcing factors causing changes in the incidence of the disease in North Pacific fish are not understood. Impact of Freshwater Predation Anadromy may have evolved as a consequence of differences in size-dependent predation rates and foraging opportunities between the marine and freshwater environments (Gross 1987)
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. Mechanisms responsible for annual variability in predation include risk dilution by alternative prey -- for example, predation rates on chum salmon fry may be reduced when pink salmon fry are abundant (Salo 1991)
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used circumstantial evidence to make a convincing case that pink salmon populations in British Columbia have been caught in predator pits and Burgner (1991) used data from the little Togiak River in Bristol Bay (Ruggerone and Rogers 1984)
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One such study is ADF&G's capture and confinement project to reduce Arctic char predation on sockeye salmon smolts in the Wood River Lakes, Bristol Bay, Alaska (Meacham and Clark 1979)
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Some residents of the AYK region have suggested that changes in predator abundance might have contributed to recent declines in salmon or, even after human fishing pressure was relaxed, could prevent recovery of populations. Explicit examples include beluga whales at river mouths and piscivorous fish and birds that experience less hunting than before.
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From page 73... ...
Late runs and smaller than average body sizes of salmon returning to western Alaska in 1997-1998 indicated that adult salmon also may have been affected by these unusual conditions. Perhaps high sea temperatures along adult migration routes in the eastern Bering Sea or other factors, such as increased parasitism, predation, competition, and disease, caused the death of many adult salmon.
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for coho salmon. The results of fieldoriented process studies and computer modeling research over the past decade indicate that food and nutrients are a major link between climate and the growth and survival of immature and maturing salmon in the Bering Sea and North Pacific Ocean.
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. In winter, low lipid levels measured in immature salmon caught in the North Pacific Ocean suggest that fish are close to starvation (Nomura et al.
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reviewed information on 34 potential marine mammal predators of salmon in the North Pacific and contiguous seas, including 15 species known to prey on salmon. Predation on free-swimming salmon (when they are not caught in nets or other fishing gear)
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on milling adult salmon in coastal marine waters, bays, and estuaries is commonly observed. Studies of diets and movements of salmon sharks in Alaska's PWS by Auke Bay Laboratory scientists in 1998-2001 indicated that salmon sharks are attracted to adult salmon returning to hatcheries and rivers in PWS, consuming 12% of pink salmon runs and 29% of chum salmon runs to Port Gravina in 2000 (L.
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A thorough investigation of marine predation mortality of AYK salmon will require coordinated ecosystem research and monitor
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High flows might increase migratory costs of chum, coho, and Chinook salmon spawning in the upper Yukon River by increasing the velocity of water they have to swim against. However, upstream migrants take advantage of the slower water near the stream bed and banks; as a result, the relationship between stream discharge and the velocity against which fish swim will depend on the bathymetry of the channel.
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The way this affects the energy expenditure of upstream migrants is unknown but may be worth investigating. Increased logging in the AYK region can be expected to change the pattern of large wood recruitment to these rivers in the future.
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In general, low flows, high temperatures, and clear water are likely to increase the risk of predation by making it easier for aquatic and avian predators to see smolts and by increasing the metabolic rate of aquatic predators. The Yukon River and its major tributaries are turbid systems; however, it is possible that reductions in the input of glacial silt in the future will reduce turbidity and make outmigrating smolts more vulnerable to predation.
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For example, it might be relatively straightforward to estimate predation rates on pink salmon fry in the Nome River, but it would be vastly harder to estimate the mortality of smolts from a stock of Chinook in the Yukon River drainage during their migration to the ocean. Incorporating measurements on life history stage-specific mortality rates to determine the role of predation in population and dynamics is likely to be much harder than simply measuring mortality rates for a single stage and a single year.
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· How do anthropogenic factors alter predation mortality of AYK salmon (for example, climate change, hatchery releases, and largescale marine fisheries)
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to the oceanic regions where AYK salmon migrate? To adequately address these and other questions about predation mortality of AYK salmon, better information is needed on the distribution, life history, ecology, and population dynamics of the major marine predators of salmon and their trophic community structure in the Bering Sea and North Pacific Ocean.
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Fishing gear for subsistence salmon fishing is regulated in terms of type of gear and its length, where the gear can be deployed, and duration of use. Yukon Historically, fishing gear used for subsistence salmon fishing in the lower Yukon River drainage included dip nets, traps with fences, and drift and set gill nets made of willow or spruce root, sinew, baleen, or seal skin (Pete 1991)
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In areas where no commercial fisheries exist, subsistence salmon fishing is allowed either 5 or 7 days per week. Kuskokwim River Historically, fishing gear used for subsistence salmon fishing in the Kuskokwim River drainage included spears, dip nets, gill nets, weirs, and traps (Oswalt 1980, Charnley 1984, Stokes 1985, Coffing 1991)
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Most nets were 25 fathoms or less in length until the 1980s. Since the 1980s, typical subsistence salmon fishing gear has included the use of drift gill nets, set gill nets, fish wheels, and rod and reel in the Kuskokwim drainage.
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Changes in Commercial Fishing Gear and Catch2 FILLER Throughout the AYK salmon management region south of Kotzebue Sound -- composed of the Kuskokwim, Lower Yukon, Upper Yukon, and Norton Sound River systems -- fishing gear has become more efficient since the late 1970s. Wooden boats have been replaced by aluminum boats with greater horsepower; lighter nylon netting (which is easier for fishermen to manage)
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While cotton twine gill nets were used through the 1970s, use of multifilament gill net web increased during the 1980s. In addition, commercial fishermen in the lower Yukon River switched from using predominantly set net gear to drift gill net gear in the early 1980s, which is believed to be more efficient at capturing salmon.
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as they are more economical to operate. Commercial fishing is allowed with set or drift gill nets.
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BOF action during the 2003 season provided ADF&G authority to establish closed periods before, during, and after commercial fishing periods to ensure that subsistence fishers had reasonable fishing opportunities. Norton Sound and the Nome Subdistrict In the 1960s, when commercial salmon fishing started in Norton Sound, boats were wooden and 15-20 ft long.
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were mandated in certain locations and periods by emergency order. In 1986, ADF&G began restricting mesh size to 6 inches or less between July 1 and July 15 to protect Chinook salmon and target the fishery on chum and coho salmon.
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Without a viable commercial market for salmon in the AYK region, it is unlikely that commercial fishing effort will rebound to the level experienced in the 1980s and early 1990s anytime soon. However, commercial fishing gear still will be used for subsistence fishing within regulatory limits (mesh size, opening times)
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For the purposes of this report, we define it as fishing by people who have bought an Alaska sportfishing license. In the AYK region, sportfishing usually is conducted with rod and reel.
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In general, better management information exists about guided anglers than about nonguided ones, because Alaska law requires guides to register with ADF&G, and they must work for a registered fishing-service business, although the degree of compliance with and enforcement of this law also is not well known. The above sample of Alaska sportfishing regulations information is provided to show that information on the aggregate effect of sportfishing on salmon populations in the AYK region is neither well known nor easy 5See http://www.adfg.state.ak.us for more information.
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cases, sportfishing occurs after commercial fishing and therefore has no direct influence on commercial catch. Also, sportfishers do not take many fish in the AYK region.
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. Commercial gears for catching salmon in the ocean have included traps, beach seines, purse seines, drag seines, drift gill nets, and set gill nets, among others.
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For example, the 2003 Yukon River Chinook salmon and fall chum salmon runs were the strongest in recent years and supported small commercial harvests (NPAFC 2003)
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The effect of these fisheries on returns of salmon to the AYK region was substantial. For example, Yukon River (immature age 1.2 fish)
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As the Japanese high-seas salmon driftnet fisheries were further reduced, new Asian pelagic squid driftnet fisheries developed rapidly in the North Pacific Ocean in the early 1980s. The squid driftnet fisheries legally intercepted salmon as part of their bycatch, but substantial illegal directed salmon fishing also occurred.
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With respect to other types of high-seas fishing gear and fisheries, information on salmon bycatch and illegal directed fishing for salmon is largely anecdotal. The effect of groundfish trawl fisheries operating in the Bering Sea and Gulf of Alaska on returns of Chinook and chum salmon to the AYK region has been a major concern since 1977, when the NMFS scientific observer program began to provide estimates of salmon bycatch by foreign vessels operating in the U.S.
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groundfish trawl fisheries, including the lack of recent estimates of stock composition, and recommended that a high priority be given to salmon stock composition research. There are also commercial trawl fishing fleets operating inside the Russian 200-mile zone in the Bering Sea, Commander Islands, and western North Pacific Ocean that may intercept at least some AYK salmon.
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There are few published studies of competitive interactions among salmon species, particularly for the AYK region. One study by Ruggerone and his colleagues (2003)
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Accurate stock identification is essential to managing mixed-stock fisheries. Despite its importance, we have limited information about AYK salmon stock structure, and our knowledge of population structure in other regions of North America is likewise limited (Utter and Allendorf 2003, see section Fishing and Genetics of AYK Salmon in this chapter)
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. In the Bering Sea, 45% of the chum salmon were of Japanese origin, 38% Russian, and 15% Alaskan, while in the North Pacific Ocean the mixture was 15% Japanese, 62% Russian, and 22% Alaskan.
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From page 106... ...
is conducting genetic and salmontagging studies to learn more about stock-specific migration patterns and run timing of salmon in the Bering Sea and North Pacific Ocean. In addition, NMFS/Auke Bay Laboratory scientists have used genetic baselines to estimate the stock composition of salmon in illegal high-seas salmon catches.
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From page 107... ...
An extensive genetic baseline has been developed for chum salmon, and scientists are developing baselines for the other species. Aside from genetics, some Norton Sound stakeholders suggested using physical tags in a mark-recapture experiment to estimate interceptions of AYK salmon by nonterminal fisheries by using releases of large numbers of marked salmon from a central incubation facility to estimate interceptions of North Sound salmon in local and distant-water commercial fisheries (T.
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Along with the development of genetic tools and their applications to various ocean fisheries, a comprehensive plan to reduce ocean interceptions of AYK salmon could be developed. Past experience indicates that successful bycatch-reduction plans involve partnerships among scientists, fishing industry representatives, resource managers, subsistence user groups, and policy makers (National Fisheries Conservation Center 1994)
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Understanding the fluctuation of the human population within the AYK region should provide insight into the variability in salmon populations. Changes in human population and its distribution within the region, as well as variability in salmon harvest and use by the human population, serve in examining the human population during the past 100 years.
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For example, while the influx of Russians was relatively small and associated with the early fur trade, their report of the 1838 smallpox epidemic in the AYK region describes the devastation to and reduction of the indigenous population extending from Fort St. Michael (near presentday St.
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Population Changes Across the AYK Region Every 10 years, the federal government estimates the human population of communities in the AYK region. During the intervening years, the state of Alaska estimates population and other key socioeconomic indicators through its Census and Geographic Information Network (ADCED 2004, ADLWD 2004)
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. During 1950-2000, the population of the Norton Sound region doubled from about 3,600 people to more than 7,000; both the regional center of Nome and the village populations doubled (ADCED 2004, Wolfe 2003)
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Uses of Salmon ADF&G continues to monitor the harvest of salmon for subsistence, commercial, and sport uses in the AYK region. These monitoring
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Both ADF&G and the federal Office of Subsistence Management of the Fish and Wildlife Service (FWS 2004) conduct or contract for studies of subsistence harvest patterns, including salmon fishing, by residents of the AYK region.
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Subsistence salmon fisheries continue to be of major importance to villages, not only as a source of food and livelihood, but also for cultural continuity and maintaining strong family relationships. The significance of salmon fishing in AYK communities is evident also in the level of participation by households and the extent of sharing regardless of the amount of salmon caught (ADF&G 2002)
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. Trends in the salmon fisheries are most precise since 1989 when the method for recording subsistence salmon catches in the AYK region reached a point that recording and estimating harvests became consistent, statistically sound, and comprehensive (at most, all communities were surveyed)
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· What are the predicted increases in human population and its distribution in the AYK region in the next 20 and 40 years, and what are some predictable outcomes of salmon harvest and use? Answering these questions requires analyzing existing information from human population censuses and salmon harvest estimates.
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From page 118... ...
Modeling the projected growth of the human population and its distribution in the AYK region is likely to provide insight on some issues that may emerge relative to salmon harvest and use. These models can aid communities in evaluating the reliability of salmon as a source of food and livelihood in generations to come.
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Dual state and federal management of subsistence salmon fisheries is complicated further by forces external to the AYK region. For example, the lack of information about the spawning destination of fish taken in intercept fisheries (such as in Area M)
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RESTORATION Background on Fish Restoration Successes and Failures The committee is reluctant to recommend specific restoration options, except at small scales and locally, because it remains uncertain what the major factors affecting salmon populations are. It is not even certain that the low runs of AYK salmon in the 1990s and early 2000s
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is not applicable directly to restoring AYK salmon. Indeed, despite that knowledge, the degree of success that restoration efforts in those places have had is not enormously encouraging, and the most successful efforts have involved habitat restoration, which is not obviously a major issue in the AYK region.
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Hatchery releases of all species of salmon from Alaska and Asia amount to several billion fish per year. Thus, biological competition between AYK salmon and hatchery salmon occurs primarily in the ocean and not within the AYK region.
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. Because of broad seasonal changes in high-seas salmon distributions, the greatest potential for competition between AYK salmon and Asian hatchery salmon occurs in winter, spring, and early summer in the North Pacific Ocean and in summer and fall in the Bering Sea.
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A research plan should be developed to investigate the roles of climate change and marine-derived nutrients on AYK salmon stocks and later to study the use of artificial enhancement intervention.
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INCORPORATING TRADITIONAL KNOWLEDGE AND COMMUNITY INPUT INTO RESEARCH Traditional knowledge and indigenous researchers must be involved at all levels of research within their traditional homelands and on the resources they depend on. Because indigenous people have such an extensive, historical, and indivisible affinity to the land they call home and a fundamental interest in the outcome of all research, they have a much greater need to be involved.
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From page 126... ...
The primary reason for declining traditional knowledge, closely linked to the land and tribal status changes, is a rapid change from a traditional, landbased lifestyle to a lifestyle detached from the natural environment more dependent on others -- for example, grocery stores and governmental programs. Indigenous people have shared traditional knowledge within their own societies and with explorers (new arrivals also)
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From page 127... ...
Most studies have been conducted through the ADF&G Subsistence Division, focusing primarily on human use of harvested wild resources. To some extent ADF&G has studied community and individual use of salmon in every village on the Yukon River.
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The problem of focusing on a single species is illustrated in discussions in this chapter of predator-prey relationships in the AYK region. The most promising development for incorporating traditional knowledge into traditional science has been occurring within the indigenous community.
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It is much easier -- challenging though it might be -- for a nonscientist to learn the methods of science than it is for someone from outside the Alaska Native culture to learn the Natives' way of knowing. It is necessary to identify and encourage indigenous and collaborative research projects that weave traditional science and traditional knowledge with Western science, including the consolidation of salmon research into a library, including geographic information system data.
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From page 130... ...
130 ARCTIC-YUKON-KUSKOKWIM SALMON from elders to schoolchildren should be represented where appropriate. One possibility would be the involvement of school students in marine science activities, as for example is being done at Little Diomede, Alaska (K.
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