Endangered and Threatened Fishes in the Klamath River Basin Causes of Decline and Strategies for Recovery (2004) / Chapter Skim
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6. Causes of Decline and Strategies for Recovery of Klamath Basin Suckers
6. Causes of Decline and Strategies for Recovery of Klamath Basin Suckers
Pages 214-249
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From page 214... ...
CRITERIA FOR JUDGING STATUS AND RECOVERY OF SUCKER POPULATIONS Criteria for the assessment of status anti recovery provide a useful point of departure for the causal analysis of clecline of the enciangerecI suckers anti for evaluating proposals for their restoration. Criteria presented here 214
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From page 215... ...
Indications of no recovery without further environmental change, however, inclucle the failure of aclults to show an upward turn in overall abundances ancI the lack of a cliversifiecI age structure among oicler age classes, presumably because of repeated mass mortality of large fish.
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From page 216... ...
It is possible that they once migrated well into the upper Klamath basin (above Klamath FalIs) , as did Chinook and steelhead, but there are no records of this, perhaps because most people are unable to distinguish them (Snyder 1 93 1 1.
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From page 217... ...
Lack of recruitment of young fish into the subaclult ancI aclult stages indicates lack of reproduction or negligible survival of young fish. Two aciclitional locations, Lower I(lamath Lake ancI Lake of the Woods, are listecI even though they lack enciangerecI suckers.
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From page 218... ...
Water quality anti habitat conditions may be unsuitable, but suitability can be cleterminecI most effectively by monitoring of trial reintroductions. To the extent that maintenance of higher water levels wouicI interfere with agricultural use of lancI, its establishment wouicI require negotiations anti compensation for .
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From page 219... ...
For example, operation of unscreened canals is an ultimate cause of mortality of fish in various life stages. Human actions that have lecI to changes in the water quality of Upper Klamath Lake are ultimate causes of mass mortality of large fish.
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From page 220... ...
The figure shows the life stages of the enciangerecI suckers as presented in Chapter 5 ancI identifies potential proximate causes of suppression of each life stage. Because the life stages are interconnected clevelopmentally, the unclerlying premises of the diagram are that suppression of any life stage contributes at least potentially to suppression of the overall population ancI that a potential remedy for the suppression of the population lies in the identification ancI reversal of the suppression of incliviclual life stages.
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From page 222... ...
Where it can be shown that the clams clo not allow passage of fish attempting to spawn, they shouicI be removed or, if a clam must be retained, it shouicI be fitted with a functional bypass. The only moclerately large clam on a tributary to Upper I(lamath Lake is Chiloquin Dam, which blocks the Sprague River near its confluence with the Williamson River (Figure 1-31.
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From page 223... ...
Removal of Chiloquin Dam has high priority ancI shouicI be pursued aggressively. In the interim, spawning fish couicI be captured at the base of the fish lacicler anti releasecI immecliately above it; some of the releasecI fish shouicI be fitted with transmitters.
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From page 224... ...
. Uncler conditions prevailing in 1990-2001' full pool elevation was achieved cluring the spawning interval in 6 of 10 yr; in 4,143.5 4,143.0 Upper Klamath Lake Water Level, March - May au au ` 4,142.5 au 1 5au 4,142.0 4,141.0 4,140.5 , , , , , , , , , , , MAM MAM MAM MAM MAM MAM MAM MAM MAM MAM MAM MAM 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 Undiminished Somewhat Diminished Diminished Severely Diminished au 5.
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From page 225... ...
Figure 6-3 shows the relationship between water level of Upper I(lamath Lake in April (in the micicIle of the critical period anti relative abunciances of larvae as shown by the stanciarclizecI sampling program. Minor differences in relative abundances of larvae shouicI not be consiclerecI significant because the sampling variance for any given year is substantial (95°/0 confidence limits extend 50-100% around the mean in most cases)
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From page 226... ...
As inclicatecI in the figure, the 2 yr of extraorclinarily low water levels (1992 ancI 1994) , which wouicI be expected to show most strongly the negative signal involving larval production, clo not indicate any repression of the year classes relatecI to water level.
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From page 227... ...
4142.6 4142.8 4143.0 FIGURE 6-4 Relative abundance of year classes of suckers in Upper I(lamath Lake, as inferred from fish recovered after mass mortality in 1997, in relation to water level during spawning interval when same year classes were produced. Source: USGS, unpublished data, 2001.
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From page 228... ...
Even subtle changes, which might involve pumping of grounc~water in the vicinity of these spawning sites, lancI disturbance, recreational activities, poorly managed agricultural practices, ancI other human activities couicI easily clegracle or even eliminate these sources of sucker fry. Abandonment of Spawning Areas Some historical spawning areas have been abanclonecI for no apparent physical reason.
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From page 229... ...
The WoocI River has hacI the only recent spawning activity, most of it attributed to shortnose suckers. Aclults were last seen in the WoocI River in 1996, ancI larvae were last collectecI in 1992; no juveniles were founcI in 2000 (Simon ancI Markle 1997b, 2001; Cooperman ancI Markle 20031.
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From page 230... ...
19861. In Upper I(lamath Lake, however, the frequencies of anomalies among the larval ancI juvenile shortnose suckers averaged 8%' ancI among the Lost River suckers averaged 16% (Plunkett ancI Snycler-Conn 20001.
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From page 231... ...
Speculation has clevelopecI about the source of the young fish that reach the Link River. They may come from known spawning sites along the northeastern portion of Upper I(lamath Lake, from such tributary streams as the Williamson River, or from unknown spawning sites farther south.
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From page 232... ...
Higher water levels in Upper I(lamath Lake are associated with larger amounts of emergent vegetation (Table 6-21. Ignoring emergent vegetation, total shoreline area that is at least 1 ft creep at lake water levels of 4,142-4,143 ft accounts
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From page 233... ...
for at least 50°/O of the lake's perimeter, but this fraction cleclines rapicTly with reclucecT water levels. Very little emergent vegetation is available to larval suckers below a lake level of 4,141 ft.; emergent vegetation is essentially inaccessible below 4,140 ft (Reiser et al.
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From page 234... ...
If interannual variations in lake level correspond to relative clegrees of repression of larval production, ancI this factor has a major effect on the populations, year classes proclucecI in years of especially low water levels in Upper I(lamath Lake shouicI be exceptionally weak. Once again, this is not the case (Figure 6-61.
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From page 235... ...
One potential line of investigation wouicT be to examine the cTifferences in larval production of the two sucker species. The two species appear to be responding in similar ways to environmental change, but the ciata 40 35 30 2520G au 15 10 | · Shortnose Suckers 1991 | a; Lost River Suckers 1992 1990 .
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From page 236... ...
The known biology of the suckers indicates that particular depths are preferred at establishecI spawning locales ancI that flooclecI emergent vegetation is primary larval habitat. The lack of relationship between water level in Upper I(lamath Lake ancI larval production or larval survival indicates that other factors, such as clegraclecI water quality or poor larval habitat, override the presumed benefits of clepth-relatecI habitat availability.
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From page 237... ...
Entrainment of fish from Upper I(lamath Lake via the Link River still occurs through intake structures of the Link River Dam, which shouicI be screened (USFWS 20021. Mass Mortality Unlike most other imperilecI lakesuckers, suckers of Upper I(lamath Lake suffer from episodic mass mortality of reprocluctive-age fish.
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From page 238... ...
become concentrated in specific refuge areas, inclucling Pelican Bay, Odessa Creek, anti the Williamson River mouth. Refuges often contain springs that offer much better water quality than the lake itself (Bienz anti Ziller 19871.
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From page 239... ...
Fish kills have occurred in years of low, average, and above-average median August lake levels. Water level may affect the accessibility of refuges that are reportedly used by large fish during periods of poor water quality and fish kills, but the data on this topic are largely anecdotal (see Buettner 1992 unpublished memo, USFWS 2002, Appendix C, and below)
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From page 240... ...
Loss of Habitat Adult Lost River suckers and shortnose suckers prefer open water; they use flowing waters chiefly for spawning. Total lake habitat available to suckers throughout the I(lamath basin is a fraction of its original extent because of drainage and other water-management practices (Chapter 21.
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From page 241... ...
luvenile suckers suffered infestation with copepocis ancI trematodes of O-7% in 1994-1996 and 9-40% in 1997-2000; shortnose suckers generally show higher rates of infestation than Lost River suckers (USFWS 2002 basecI on Carison et al.
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From page 242... ...
, to restore water quality if possible, ancI to prevent movement of nonnative fishes within the basin. Selective control of nonnative species has been pursued in some environments (Ruzycki et al.
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From page 243... ...
Apparent hybrids, as inclicatecI by morphological intermediacy, are commonly found in the Williamson River downstream of Chiloquin Dam ancI in sucker populations of Clear Lake, where crosses between Lost River suckers ancI I(lamath largescale suckers are most frequently suspected (e.g., Cunningham et al. 2002; Moyle 2002; D
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From page 244... ...
Even the I(lamath largescale suckers in the upper I(lamath basin ancI I(lamath smaliscale suckers in the lower basin seem not as affectecI by anthropogenic change as Lost River ancI shortnose suckers, although the I(lamath largescale sucker is listecI as a species of special concern in California (Moyle 20021. IntroclucecI species, such as yellow perch ancI fathead minnow, appear to be unaffected by poor water quality.
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From page 245... ...
All except Gerber Reservoir are habitat units for both sucker species; Gerber Reservoir contains only shortnose suckers, but Lost River suckers presumably could live there. The ciraft critical-habitat determination (59 FecI.
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From page 246... ...
identified sites that have the greatest potential as adult refuges at low lake levels on the basis of their size, proximity to the main lake, relative water quality, ancI density of submerged vegetation. The issue of water-quality refuges neecis more stucly relative to critical habitat.
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From page 247... ...
Even slight improvements in conditions favorable to suckers in Upper I(lamath Lake, its tributaries, anti surrounding water bodies couicI contribute to recovery. CONCLUSIONS Despite elimination of fishing for the shortnose anti Lost River suckers in 1987, these two listecI species have failecI to show an increase in overall
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From page 248... ...
Physical restoration near the mouth of the Williamson River as it enters Upper I(lamath Lake is also important. Water level in Upper I(lamath Lake shows no relationship to waterquality conditions that result in mass mortality of aclult suckers or other potentially adverse water-quality conditions.
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From page 249... ...
Suckers of Upper I(lamath Lake ancI at other locations where suckers are present in the upper basins share their habitat to varying degrees with nonincligenous species, some of which are known to prey upon or compete with young suckers. Elimination of nonincligenous species over very large systems such as Upper I(lamath Lake is beyond the current state of the art, but programs clesignecI to prevent aciclitional introductions ancI prevent the spreacI of presently nonincligenous species wouicI be highly acivisable.
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