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Annual survey of abundance and distribution of age 0 shortnose and Lost River suckers in Upper Klamath Lake
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One chapter of a seven chapter annual report from 1999 examining ecological issues regarding the shortnose and Lost River sucker populations in Upper Klamath Lake and Williamson River., ECOLOGY OF UPPER KLAMATH LAKE SHORTNOSE AND LOST RIVER SUCKERS 3. Annual survey of abundance and distribution of age 0 shortnose and Lost River suckers in Upper Klamath Lake 1999 ANNUAL REPORT ( partial) SUBMITTED TO U. S. Biological Resources Division US Geological Survey 104 Nash Hall Oregon State University Corvallis, Oregon 97331 - 3803 & Klamath Project U. S. Bureau of Reclamation 6600 Washburn Way Klamath Falls, OR 97603 by David C. Simon, Mark Terwilliger & Douglas F. Markle Oregon Cooperative Research Unit 104 Nash Hall Department of Fisheries and Wildlife Oregon State University Corvallis, Oregon 97331- 3803 April 19,2000 INTRODUCTION AND OVERVIEW The Klamath Basin's endangered suckers, Chasmistes brevirostris Cope, 1879 ( shortnose sucker, SNS), and Deltistes luxatus ( Cope, 1879) ( Lost River sucker, LRS) were listed based, in part, on the perception that recruitment had failed for many years. Our sampling surveys have supported the notion that recruitment failure was an important problem and indicated the number of survivors in a year class can differ greatly. Becauserecruitment failure or variation can be caused by very small changes in mortality rates, growth rates, or stage durations in the early part of life ( Houde 1987), we have expended our efforts on the first year of life of Upper Klamath Lake suckers. Our approach to year class assessment in 1999 was identical to 1997 and 1998, and nearly identical to 1995 and 1996. We conducted 6 surveys every third week with a larval trawl from April - July to assess early season larval sucker abundance. Four beach seine surveys were conducted every third week from June - August to assess mid season juvenile sucker abundance. The last 3 larval trawl surveys were concurrent with the first 3 beach seine surveys. This multiple gear strategy ensured we remained effective on multiple cohorts. Three concurrent cast netlotter trawl surveys were conducted every third week from late August - early October to assess late summer and early fall juvenile sucker abundance. Cast net surveys assessed shoreline abundance while concurrent otter trawl surveys assessed offshore abundance. Spring random otter trawl surveys were conducted in April to assess overwinter survival of the 1998 year class ( now age 1). Water quality parameters including dissolved oxygen, pH, conductivity, and water temperature were measured for each fish sample. 0. S. U. 1999 Annual Report 2 METHODS Larval sampling Larval trawl sampling in 1999 was conducted every third week on April 6- 7, April 27- 28, May 18- 1 9, June 8- 9, June 29- 30, and July 20- 21. Two samples were collected from 10 fixed sites in Upper Klamath Lake and 5 fixed sites in Agency Lake ( Figure 1). The larval trawl has a 0.8 x 1.5 m opening with 2.5 m of 1000 micron Nitex mesh netting. The larval trawl is mounted on an aluminum frame with runners, similar to that described by LaBolle et al. ( 1 985), and was set 2- 12 m ( avg. 6.5 m) from shore by wading out and placing the trawl in water 1 m deep. The trawl was then pulled to shore with ropes. If vegetated and nonvegetated habitats were available at a site, one sample was collected from each. Because of disturbance to the area when setting the larval trawl, a minimum of 10- 1 5 minutes was waited before pulling to shore. Thirty samples were collected each survey for a total of 180 samples. Beach seine Beach seine sampling in 1999 was conducted every third week on June 8- 9, June 29- 30, July 20- 21, and August 9- 10. Two samples were collected from each of 10 fixed sites in Upper Klamath Lake and 5 fixed sites in Agency lake-the same sites as the larval trawl sampling. The beach seine was 6.1 m in length with a 2 x 2 x 2 m bag and constructed with 4.8 mm bar mesh. Each sample was collected with one person remaining on shore and the other walking perpendicular into the water while unrolling the seine until the end of the seine was reached. The offshore person then pulled the net to shore in a %- circle arc with the shoreline person remaining stationary. Samples were normally collected from waters less than 1.5 m deep and over unvegetated or sparsely vegetated shorelines. Thirty samples were collected each survey for a total of 120 samples. 0. S. U. 1999 Annual Report 3 Cast net Cast net sampling in 1999 was conducted every third week on August 23- 25, September 13- 1 5, and October 4- 6. The cast net was a 5 m diameter multifilament net with 6.3 mm bar mesh. Sampling protocol followed a stratified random design based on 8 different shoreline substrate types ( Table 1). The entire Upper Klamath Lake shoreline was mapped with hand- held GPS units in 1994 when water levels were at record lows, thus exposing the shoreline substrates and allowing us the opportunity to collect the necessary data to construct a shoreline substrate map that our cast net sampling is based upon. All cast net samples were normally collected within 10 m of the shoreline in water depths normally ranging from 0.5 - 1.0 m, and typically not exceeding 1.5 m. Cast net samples were collected from nonvegetated or sparsely vegetated locations and were collected along the edge of the vegetation wherever the shoreline was vegetated. Prior to each cast net survey, sampling sites were randomly selected within each substrate category. Latitude and longitude coordinates for each site were then mapped in GIs software. A hand- held GPS unit and the maps were used to locate each site, within the error limits of uncorrected GPS points. Often, zoomed in printouts of the mapped locations were as valuable in locating sites as was the GPS unit. Substrate type at each site was verified. During each cast net survey, a total of 140 samples were collected, for a total of 420 samples. The appropriate estimate of the mean number of suckers per cast net sample was calculated using the following formula: where: L = number of strata ( 8 here) N = total number of units available for sampling ( 2595 here) Nh = number of units in each stratum ( h) available for sampling 0. S. U. 1999 Annual Report 4 nh = number of units sampled in stratum h Yhi = value obtained ( number of fish) for thefh unit in stratum h and, - = mean of the nh values in stratum h = ( E, YW Y Density per square meter was calculated by dividing mean number per cast by 5 m2 ( the area sampled by the cast net). Shoreline abundance was then estimated by multiplying the resulting density by the total shoreline area. Total shoreline area was estimated by multiplying the linear shoreline distance by 10. We assumed 10 meters as the distance from the shore that shoreline substrates extend, but this number remains arbitrary. At a minimum, our population estimates can be considered an index of abundance. Confidence intervals for the population estimates were calculated using a bias- corrected bootstrap resampling procedure, adjusted for the fact that the true mean is not the median of the distribution of bootstrap estimates ( Manly 1997). Otter trawl late summer/ fall Three otter trawl surveys were conducted in conjunction with each cast net survey on August 26- 27, September 15- 1 6, and October 6- 7 to assess offshore abundance of age 0 suckers. A 5 m semi- balloon otter trawl with 16 mm bar mesh and a 6 mm bar mesh liner was used. Trawl directions and locations were randomly selected from a grid of coordinates at 1 km intervals covering Upper Klamath Lake. No site began within 1 km of the shore, and direction was changed in the field if the randomly selected direction was not possible. Each survey consisted of 15 tows, each tow was 20 minutes in duration, and exact distance of each tow was measured using differentially corrected GPS coordinates. This protocol was identical to 1995- 1 998. Offshore populations were estimated by multiplying the calculated offshore density ( mean number per tow divided by area sampled) by the offshore area of Upper Klamath Lake. 0. S. U. 1999 Annual Report 5 Confidence intervals were estimated using a bootstrap resampling procedure similar to that of cast net confidence intervals. Whole lake population estimates were estimated by summing cast net and otter trawl estimates. spring Two otter trawl surveys were conducted April 7- 8 and April 28- 29 to assess the 1998 year class as age 1 fish. Sampling protocol was identical to late summer/ fall sampling. RESULTS and DISCUSSION Spring otter trawl No age 1 suckers were captured in either of the two spring otter trawl surveys in April 1999. Although spring otter trawl catches are usually low, the lack of suckers in spring 1999 probably reflects a downward trend in age 0 sucker abundance we have detected from the mid- 1990s ( Simon et al. 2000) ( Figure 2). Larval trawl Sucker larvae in Upper Klamath Lake were abundant in 1999. Mean larval trawl catch rates in 1999 were higher than any year since larval sampling began in 1995, although they were similar to 1996 and 1997 ( Figure 3). Larval trawl catch rates were substantially higher than those from 1998. Other indices also suggest larvae were abundant in 1999. The proportion of positive catches ( catches > 0) was 43% in 1999, higher than 1998 but lower than 1995 or 1996 ( Table 2). The proportion of large catches (> loo) was 5.0%, much higher than 1997 or 1998, slightly higher than 1995, but lower than 1996 ( Table 2). Of the 6 larval surveys, catch rates were high in two ( Figure 4). This is a departure from previous years when catch rates were never high ( 1 998) or only high for one survey ( 1 996, 1997). Although one larval survey was high in 1997, it did not 0. S. U. 1999 Annual Report 6 persist as catches dropped by the next survey and catches with all gears remained low throughout the year. High levels of un- ionized ammonia that year may have inflicted high mortality on larvae ( Simon et al. 1998). These data suggest larval abundance in 1999 was higher than in 1997 or 1998, and similar to 1995 and 1996. There was no correlation ( r = - 0.06) among adult spawning run indices ( Markle et al. 2000) and larval indices from 1995- 1 999 ( Figure 5). Larvae were most abundant at sites U6 ( Williamson River mouth) and U5 ( Goose Bay) ( Figure 6). Other sites of high abundance included U2 ( Hagelstein Park), U10 ( Stonehouse Ranch), U7 ( Ball Bay), and U4 ( Modoc Point). Similar to other years, catch rates of larval suckers in Agency Lake were considerably lower than in Upper Klamath Lake ( Figures 3, 6, 7). Length frequencies of larval suckers are shown in Figure 8. Beach seine Age 0 suckers, as indexed by beach seine CPUE, were abundant in Upper Klamath Lake in 1999. Catch rates were lower than those from 1996 were, but higher or much higher than other years ( Figure 9, IO). The proportion of positive catches (> O) in 1999 was similar to 1995 and lower than 1996, but much higher than in 1997 and 1998 ( Table 2). Similarly, the proportion of large catches (> 25) was similar to 1995 and lower than 1996, but much higher than in 1997 and 1998 ( Table 2). These data all suggest juvenile abundance in late June through August as measured by beach seine sampling was higher than 1997 and 1998, similar to 1995, but lower than 1996. Comparisons with beach seine catches from 1991 - 1 994 are shown in Figure 9, but should be interpreted with caution, as data from these years were not collected as intensively or comparably as data from 1995- 1 999. There was little correlation ( r = 0.22) among adult spawning run indices ( Markle et al. 2000) and beach seine indices from 1995- 1 999 ( Figure 1 I), but there was a much stronger correlation ( r = 0.77) among larval trawl and beach seine indices ( Figure 12). Beach seine catches were highest at U6 Williamson River mouth), U5 ( Goose Bay), U2 ( Hagelstein Park), and U10 ( Stonehouse Ranch) ( Figure 13). 0. S. U. 1999 Annual Report 7 Beach seine catches were low in Agency Lake. ( Figures 9,13, 14). Similar to most previous years, beach seine catches were primarily shortnose sucker. Of 3244 caught, 3059 ( 94.3%) were shortnose suckers, while 185 ( 5.7%) were Lost River suckers. Based on vertebral count distribution about 1% of the suckers identified as shortnose were probably Lost River suckers. A brief examination of a small subset of suckers caught in beach seines found no specimens with lip morphology resembling that of Klamath largescale sucker. Length frequencies of suckers from beach seines ( Figure 15) seem to reflect the bimodal distribution of larval suckers emigrating down the Williamson River in 1999 ( Figure 16). Figure 16 clearly shows an early, smaller peak of emigrating larvae and a later, larger peak. These correspond well with June 29- 30 and July 20- 21 SNS length frequency data ( Figure 15) that show a large peak of younger suckers and a smaller peak of older suckers. The addition of LRS to the length frequency histogram made little difference as the large number of SNS dominated the histogram. Cast net Cast net catches in 1999 were high; a total of 872 age 0 suckers were caught. In addition to our normal routine of identification, including vertebral and gill raker counts, each specimen was carefully examined in the laboratory for lip morphology. One specimen ( 0.1 %) was identified as a Klamath largescale sucker. Of the remaining, 372 ( 43%) were Lost River suckers and 499 ( 57%) were shortnose suckers. Nearshore population estimates of age 0 Lost River sucker were 201,828 in the August survey, 65,556 in the September survey, and 59,945 in the October survey ( Table 3). Nearshore estimates of age 0 shortnose sucker were 344,681 in August, 96,338 in September, and 61,533 in October ( Table 3). Mean shoreline abundance for LRS was higher than 1995- 1 997, but similar to 1998, while mean shoreline abundance for SNS was higher than 1997 but similar to 1995- 1 996 and 1998 ( Figure 17) ( see caveat below for 1998 cast net data). Other indices suggest nearshore abundance was highest in 1999 compared to previous years. The proportion of positive catches (> 0), and the 0. S. U. 1999 Annual Report 8 proportion of large catches (> 5 and > lo) ( Table 4) were all higher in 1999 than from 1995- 1 998. Age 0 suckers were most common on gravel and small mixed particles ( Table 5) in 1999, consistent with substrate use patterns from 1995- 1 998 ( Simon et al. 2000). Catch- per- unit- effort on fine substrates was higher in 1999 ( Table 5) than from 1995- 1998 resulting from some catches in the southern end of the lake on fines. Consistent with distribution patterns from 1995- 1 998, most age 0 suckers in 1999 were found in the south end of Upper Klamath Lake ( Figure 18), with scattered catches in Ball Bay, Wocus Bay, and the eastern shoreline, and little use of the northern margins of the lake. Length frequencies of LRS and SNS from cast net sampling are shown in Figure 19. Otter trawl Otter trawl catches in late summerlfall 1999 were the highest ever. The August 26- 27 survey averaged 1 1.2 ( 9.41, LRS; 1.76, SNS) age 0 suckers per tow, well above the previous high for a survey of 1.27 in October 1995. The total number of age 0 suckers captured during this survey ( I 68) exceeded the total of 60 age 0 suckers captured in all random trawl surveys from 1995- 1 998. Of these 60, 37 were caught in 1995 and only 23 from 1996- 1 998. Catches of both species dropped in the final two surveys ( Figure 20), but the mean CPUE of all samples far exceeded the means from 1991 - 1 998 ( Figure 21). The mean of the estimated abundance of all 3 surveys for both species was higher in 1999 than any year from 1995- 1 998 ( Figure 22). Population size was not estimated prior to 1995 since sampling was from fixed sites rather than random. Of 186 age 0 suckers caught otter trawling 156 ( 84%) were LRS and 30 ( 1 6%) were SNS. None were identified as KLS, although each specimen was examined carefully for lip morphology. Offshore population estimates were 470,970 for LRS and 88,659 for SNS during in the August survey, but declined in the last two surveys ( Table 6). Length frequencies of trawl- caught suckers are shown in Figure 23. Catch distribution is shown in Figure 24. 0. S. U. 1999 Annual Report 9 Whole- lake population estimates Mean whole- lake population estimate for age 0 Lost River sucker in 1999 was the highest since we began estimating population size in 1995 ( Figure 25). The August estimate of 672,798 ( Figure 26) far exceeded the estimate of 309,632 from August 1998. Nearly 70% of the August 1999 estimate was from offshore abundance. Lost River sucker estimates in the September surveys in 1999 were similar to 1995 and higher than 1996- 1 998, and were higher in October 1999 than any other year ( Figure 26). Mean whole- lake population estimate for age 0 shortnose sucker in 1999 was also the highest, but only slightly higher than 1995, 1996, and 1998 ( Figure 25). The August estimate in 1999 for age 0 shortnose sucker was similar to 1996 and 1998, but higher than 1997, while September estimate was lower than 1995, but higher than 1996- 1 998, and October estimates were similar to 1996 and higher than 1995 and 1997- 1 998 ( Figure 27). These estimates, along with larval trawl and beach seine data, suggest that age 0 suckers in 1999 were substantially more abundant than in 1997 or 1998, and at least or more abundant than 1995- 1 996. We urge caution in interpreting the 1998 cast net data as these numbers are probably inflated from a single sample in which an inordinately large number ( 1 168) of suckers were caught. Without this sample, cast net abundance data are similar to 1997. Our larval trawl and beach seine data from 1998 are also similar to that of 1997, and suggest that these two years probably represent poor recruitment. Our data suggests 1999 was a good year for sucker recruitment. During the period 1995- 1 998, larval and juvenile sucker abundance generally declined ( Simon et al. 2000). During this same period, adult spawning run indices of both LRS and SNS also declined ( Markle et al. 2000). Adult spawning run indices continued to decline in 1999 ( Markle et al. 2000), however, larval and juvenile numbers reversed their declining trends and were abundant in 1999, suggesting a poor stock- recruitment relationship. As in all other years, age 0 LRS and SNS population estimates in September and October were less than August. September and October 0. S. U. 1999 Annual Report 10 estimates averaged 87,000 LRS, down from nearly 700,000 in August , while September and October SNS estimates averaged 85,000, down from 433,000 in August. This consistent annual trend of sharply decreasing age 0 sucker numbers in late summer and fall remains a concern. We had been concerned that suckers might move offshore during September and October, where capture efficiency of the otter trawl might be poor, and thus we would underestimate abundance. High capture numbers in otter trawl sampling during August 1999 has reduced this concern and suggest offshore densities in previous years was in fact low, particularly in 1993 and 1996- 1 998. Of continuing concern is the loss of age 0 suckers through irrigation and power canals. Gutermuth et al. ( 2000) have shown large numbers of age 0 suckers being entrained out of Upper Klamath Lake during late summer of 1997 and 1998, the same time our abundance data sharply decreased. Preliminary data from 1999 suggest entrainment patterns were similar ( B Gutermuth, pers. comm.). Water quality Dissolved oxygen ( DO) and pH values measured for each fish collection activity are shown in Figure 28. Dissolved oxygen levels fluctuated between 7.12 and 11.65 mgll and pH fluctuated between 7.42 and 9.1 0 during the first 4 sampling weeks. During the summer as Aphanizomenon blooms affected water quality, the range of DO and pH levels increased ( Figure 28). During late June through October we collected 570 samples where DO was measured. Of these, 14 ( 2.5%) had DO less than 1.62 mgll and these 14 samples caught 122 ( 2.1%) age 0 suckers. Saiki et al. ( 1999) reported 1.62 mgll DO as the mean 96 hr LCs0 value for juvenile Lost River sucker, and 1.34 mgll for juvenile shortnose suckers. Ninety eight percent of our samples ( 555 of 570, late June- October) had D0> 1.85 mgll, the minimum level reported that resulted in low mortality in caged juvenile LRS in Upper Klamath Lake ( Martin and Saiki 1999). On June 30 we measured DO to be 0.00 in Wocus Bay ( site U9) and captured 67 age 0 suckers in 4 samples. The ranges of DO concentrations for all samples and those with 0. S. U. 1999 Annual Report age 0 suckers are shown in Figure 29. All our samples were collected during the daytime and missed nighttime minima in DO concentrations. During late June through October, we measured pH at 570 samples. Of these, only 4 were pH> 10.3, the mean 96 hr LC50 reported by Saiki et al. ( 1999) for juvenile Lost River sucker. These 4 samples caught 67 age 0 suckers, and were the same 4 samples where DO was 0.00 on June 30 in Wocus Bay. Saiki et al. ( 1 999) reported mean 96 hr LC50 pH values of 10.39 for juvenile shortnose sucker. Meyer et al. ( 2000) reported pH of 10.0 as not causing significant mortality of juvenile Lost River suckers. The ranges of pH values for all samples and those with age 0 suckers are shown in Figure 29. These data suggest that elevated pH in 1999 was not a limiting water quality problem. 0. S. U. 1999 Annual Report LITERATURE CITED Cope, E. D. 1879. The fishes of Klamath Lake. American Naturalist 13: 784- 785. Gutermuth, B, E. Pinkston, and D. Vogel. 2000. A- canal fish entrainment during 1997 and 1998 with an emphasis on endangered suckers. Final Report submitted to U. S. Bureau of Reclamation. 51pp. Houde, E. D. 1987. Fish early life dynamics and recruitment variability. American Fisheries Society Symposium 2: 17- 29. LaBolle, L. D., Jr., H. W. Li, and B. C. Mandy. 1985. Comparison of two samplers for quantitatively collecting larval fishes in upper littoral habitats. Journal of Fish Biology, 26: 139- I 46. Manly, B. F. J. 1997. Randomization, bootstrap, and Monte Carlo methods in biology. Chapman and Hall. London, New York. Markle, D. F., M. Cunningham, and D. C. Simon. 2000. Ecology of Upper Klamath Lake shortnose and Lost River suckers. Part I : Adult and larval sampling in the lower Williamson River April- August 1999. Report submitted to the U. S. Bureau of Reclamation. 18pp. Martin, B. A. and M. K. Saiki. 1999. Effects of ambient water quality on the endangered Lost River sucker in Upper Klamath Lake, Oregon. Transactions of the American Fisheries Society 128: 953- 961. Meyer, J. S., H. M. Lease, and H. L. Bergman. 2000. Chronic toxicity of low dissolved oxygen concentrations, elevated pH, and elevated ammonia concentrations to Lost River suckers ( Deltistes luxatus) and swimming performance of Lost River suckers at various temperatures. Research report submitted to U. S. Bureau of Reclamation, Klamath Falls. 44 pp. Saiki, M. K., D. P. Monda, and B. L. Bellerud. 1999. Lethal levels of selected water quality variables to larval and juvenile Lost River and shortnose suckers. Environmental Pollution 105: 37- 44. Simon, D. C., M. R. Terwilliger, and D. F. Markle. 1998. Annual Report: 1997. Larval and juvenile ecology of Upper Klamath Lake suckers. Submitted to the U. S. Bureau of Reclamation. 63pp. 0. S. U. 1999 Annual Report 13 Simon, D. C., M. R. Terwilliger. P. Murtaugh, and D. F. Markle. 2000. Larval and juvenile ecology of Upper Klamath Lake suckers. Draft Final Report to U. S. Bureau of Reclamation. 107pp. 0. S. U. 7999 Annual Report 14
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Oregon Cooperative Wildlife Research Unit
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Publisher :  Oregon Institute of Technology. Library     Type :  text     Format : ; File Size: 152,000 bytes, application/pdf    
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2000, 2005-09-11, 2005-01-20
Subject :
Catostomidae -- Ecology -- Oregon -- Upper Klamath Lake; Endangered species -- Oregon -- Upper Klamath Lake
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This is chapter 3 of a 7 chapter item: Ch. 1 - ; Ch. 2 - ; Ch. 4 - ; Ch. 5a - ; Ch. 5b - ; Ch. 6 -, Digital reproduction of part of item held by Oregon Institute of Technology Library:
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Originally published as: Ecology of Upper Klamath Lake shortnose and Lost River suckers : 1999 annual report. (Corvallis, Or. : Oregon Cooperative Research Unit, 2000.), chapter 3
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