the range of values.Mean hematocrit in 1979 (49.88)was slightly higher than in 1978 (43.4X),and 858 of the fish had hematocrits above the expected maximum of 43 (for rainbow trout)in 1979 compared to 50 in 1978.None of the hematocrits or hemoglobins fell below the minimum expected values. viral Screening Both Rangen Research Laboratories and the National Fisheries Research Center (USFWS)indicated that no IPN virus was present in the Chelan (Leavenworth)Hatchery steelhead. Indirect Fluorescent Antibody Test for Bacterial Kidney Disease. One posterior kidney smear (1.78)was found to have a few BKD organisms in the Chelan (Leavenworth)Hatchery steelhead. Histopathology A detailed report on the examination and interpretation of selected tissue sections from the random samples is presented in Appendix B.A summary of the pathological conditions observed,their severity,and their frequency of occurrence is presented in Table 6.The severity is ranked as:I--recognizible (least severe),II--intermediate,and III--severe. Note that the incidence of rank II and III severity was low for all conditions encountered (Table 6). The major pathological conditions encountered in the Chelan (Leavenworth)Hdatchery steelhead were of lymphocyte infiltration and epithelial hypertrophy in gill tissue and the presence of sporozoan parasites. Records (Table 2)indicate the total mortality in the hatchery was 15号. 17
the range of values. Mean hematocrit in 1979 (49.8%) was slightly higher than in 1978 (43.4X), and 85% of the fish had hematocrits above the expected maximum of 43% (for rainbow trout) in 1979 compared to 50% in 1978. None of the hematocrits or hemoglobins fell below the minimum expected values. Viral Screening Both Rangen Research Laboratories and the National Fisheries Research Center (USFWS) indicated that no IPN virus was present in the Chelan (Leavenworth) Hatchery steelhead. Indirect Fluorescent Antibody Test for Bacterial Kidney Disease. One posterior kidney smear (1.7%) was found to have a few BKD organisms in the Chelan (Leavenworth) Hatchery steelhead. Histopathology A detailed report on the examination and interpretation of selected tissue sections from the random samples is presented in Appendix B. A summary of the pathological conditions observed, their severity, and their frequency of occurrence is presented in Table 6. The severity is ranked as: I--recognizible (least severe), II--intermediate, and III--severe. Note that the incidence of rank II and III severity was low for all conditions encountered (Table 6). The major pathological conditions encountered in the Chelan (Leavenworth) Hdatchery steelhead were of lymphocyte infiltration and epithelial hypertrophy in gill tissue and the presence of sporozoan parasites. Records (Table 2) indicate the total mortality in the hatchery was 15%. 17
Table 6.--Pathological conditions observed in the homing stocks and their perceatage of ineidence. k gg9日g8988,8,86:。8 0 ted with bactertal kidney di olfactory 管目山岛通 。)。。月。。A。。AA。1。。21.1 出：g”g。。。州。：小1：；L888丝 888g,8日：g日日日日8g日日8日8 a…
Table 6.--Pathological conditions observed in the homing stocks and their percentage of incidence
Seawater Adaptation At the time of introduction to seawater,the test group contained mostly transitional and smolted fish,with 7%classified as precocious males.These precocious fish had all died by 82 days of seawater residence.Cumulative losses due to osmoregulatory dysfunction during the first 30 days in seawater were about 288 in spite of 488 of the fish being smolted at seawater entry.Reversion from an apparent smolt or transitional stage to a transitional or parr stage,did take place after 82 days in seawater.This suggests that those fish which were judged to be smolts based upon external characteristics were not physiologically true smolts,or that high seawater temperatures may have forced reversion. Vibrio Strain 775 was the bacterial pathogen most commonly isolated from moribund fish.The 30-day survival was 598,and the survival after completion of the tests (207 days)was only 8 (Table 7). Wells Hatchery (Transferred to Winthrop Hatchery)Steelhead Gill Na+-K+ATPase In 1978,Na+-K+ATPase activities were determined on representative samples of Wells Dam Hatchery (rearing pond)steelhead,sampled at Winthrop Hatchery on 3 May.These fish had average gill Na+-K+ATPase activity of 17.0 (t 5.1),with values ranging from 11.6 to 26.6.The sampled fish averaged 22.5 cm fork length and 102.2 g body weight and were judged to be in a good smolted condition. In 1979,the average length and weight of samples transferred to Manchester were 21.7 cm and 97.0 g (respectively)on 11 May 1979.The average gill Na+-K+ATPase activity from Wells Hatchery fish at Winthrop Hatchery on 19 May was 16.5 (+9.2),with values ranging from 8.2 t037.1. 19
Seawater Adaptation At the time of introduction to seawater, the test group contained mostly transitional and smolted fish, with 7% classified as precocious males. These precocious fish had all died by 82 days of seawater residence. Cumulative losses due to osmoregulatory dysfunction during the first 30 days in seawater were about 28% in spite of 48% of the fish being smolted at seawater entry. Reversion from an apparent smolt or transitional stage to a transitional or parr stage, did take place after 82 days in seawater. This suggests that those fish which were judged to be smolts based upon external characteristics were not physiologically true smolts, or that high seawater temperatures may have forced reversion. Vibrio Strain 775 was the bacterial pathogen most commonly isolated from moribund fish. The 30-day survival was 59%, and the survival after completion of the tests (207 days) was only 8% (Table 7). Wells Hatchery (Transferred to Winthrop Hatchery) Steelhead Gill Na+-K+ ATPase In 1978, Na+-K+ ATPase activities were determined on representative samples of Wells Dam Hatchery (rearing pond) steelhead, sampled at Winthrop Hatchery on 3 May. These fish had average gill Na+-K+ ATPase activity of 17.0 (± 5.1), with values ranging from 11.6 to 26.6. The sampled fish averaged 22.5 cm fork length and 102.2 g body weight and were judged to be in a good smolted condition. In 1979, the average length and weight of samples transferred to Manchester were 21.7 cm and 97.0 g (respectively) on 11 May 1979. The average gill Na+-K+ ATPase activity from Wells Hatchery fish at Winthrop Hatchery on 19 May was 16.5 (± 9.2), with values ranging from 8.2 to 37.1. 19
Table 7.--Survival daring seavater calture periods and causes of sortality vater aurviva in Causes of sortality during seavater culture Stock and species 。 ee58”ro .00.4 3.4 03.80061.8 d 17.5 1a-m 0.74.600 94.8 seeisead 30-79 10.0 026.71.70 61.7 spring chincok 02-79 Nubers examined vere not sufficiest to evaluste. 1.3 0.49 1.1 05.700 1.1 8
Table 7.--Survival during seawater culture periods and causes of mortality. Chelan-Leavenorth 200 59 16 207 8.0 0.44 3.4 0 34.8 0 0 61.8 steelhead 4-27-79 11-20-79 Wells 200 17.5 9 193 4.5 0.49 0 0.7 4.6 0 0 94.8 steelhead 5-11-79 11-20-79 Tucannon 200 48.5 37 190 18.5 0.43 10.0 0 26.7 1.7 0 61.7 steelhead 5-15-79 11-19-79 Carson 200 56.5 41 202 20.5 0.39 Numbers examined were not sufficient to evaluate. spring chinook 5-02-79 11-20-79 Big White Salmon 150 93.3 11 189 7.3 0.49 7.1 0 85.7 0 0 7.1 fall chinook 5-21-79 11-26-79
Plasma Electrolytes As in 1978,there were noticeable differences in the plasma electrolytes of the Wells-Winthrop Hatchery steelhead when compared to the other steelhead stocks in these studies (Table 3).There was only one sample taken (at the time of release),but this stock again had the lowest mean Nat and K+values,even lower than in 1978 (Table 3). There were no differences in transportation techniques or water quality in 1979 between stocks,thus no obvious stresses were involved In 1979,plasma chloride was also measured.In 1978,the mean plasma chloride level (108 meq/1)was below the expected value of 111 meg/l for healthy rainbow trout.In 1979,none of the chloride values (X =133 meq/1)were below normal. Hematology The hematocrit and hemoglobin data for the Wells Hatchery steelhead are presented in Figure 4.In 1978,the Wells Hatchery steelhead had the highest mean hematocrit and hemoglobin values of any of the steelhead stocks that we studied (Table 3).In 1979,84.98 were above the expected maximum (43)hematocrit level and 51.7 above the maximum expected 9.3 g/100 ml blood hemoglobin value.None of the hematocrit or hemoglobin values were below the expected minimums. Viral Screening Rangen Research Laboratories reported IPN virus in 12 out of 12 pooled samples in the Wells Hatchery steelhead,and the National Fisheries Research Center (USFWS)reported all samples negative for IPN virus. Indirect Fluorescent Antibody Test for Bacterial Kidney Disease Two out of 60 fish sampled (3.3%)from the Wells (Winthrop)Hatchery steelhead were found to have light BKD infections in anterior or posterior kidney 21
Plasma Electrolytes As in 1978, there were noticeable differences in the plasma electrolytes of the Wells-Winthrop Hatchery steelhead when compared to the other steelhead stocks in these studies (Table 3). There was only one sample taken (at the time of release), but this stock again had the lowest + mean Na and K+ values, even lower than in 1978 (Table 3). There were no differences in transportation techniques or water quality in 1979 between stocks, thus no obvious stresses were involved. In 1979, plasma chloride was also measured. In 1978, the mean plasma chloride level (108 meq/l) was below the expected value of 111 meg/l for healthy rainbow trout. In 1979, none of the chloride values (X = 133 meq/l) were below normal. Hematology The hematocrit and hemoglobin data for the Wells Hatchery steelhead are presented in Figure 4. In 1978, the Wells Hatchery steelhead had the highest mean hematocrit and hemoglobin values of any of the steelhead stocks that we studied (Table 3). In 1979, 84.9% were above the expected maximum (43%) hematocrit level and 51.7% above the maximum expected 9.3 g/100 ml blood hemoglobin value. None of the hematocrit or hemoglobin values were below the expected minimums. Viral Screening Rangen Research Laboratories reported IPN virus in 12 out of 12 pooled samples in the Wells Hatchery steelhead, and the National Fisheries Research Center (USFWS) reported all samples negative for IPN virus. Indirect Fluorescent Antibody Test for Bacterial Kidney Disease Two out of 60 fish sampled (3.3%) from the Wells (Winthrop) Hatchery steelhead were found to have light BKD infections in anterior or posterior kidney. 21