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Pen rearing and imprinting of fall Chinook salmon. Annual report 1989

The goal of this project is to compare net-pen rearing methods to traditional hatchery methods of rearing upriver bright fall chinook salmon (Oncorhvnchus tshawvtscha). Fish were reared at several densities in net pens at three Columbia River backwater sites during 1984-1987, and in a barrier net at one site during 1984-1986; methods included both fed and unfed treatments. The purpose of this report is to summarize the results obtained from the unfed treatments and the current return of adults from all fed treatments and the barrier net. Zooplankton were the primary food item of unfed fish. Fish reared in net pens utilized insects colonizing the nets as an additional food source, whereas those reared in the barrier net did not. Growth and production of fish reared in the unfed treatments were low. Instantaneous growth rates of unfed fish were much lower than those of the fed treatments and hatchery controls except when zooplankton densities were high and chironomid larvae were important in the diet of unfed fish reared in pens. Only fish in the barrier net treatment resulted in consistent net gains in growth and production over the rearing periods. Adult returns of fish from all fed and unfed treatments are lower than those of control fish reared at the hatchery. Returns appear to be inversely related to rearing density. Even though adult returns are lower than those of traditional hatchery methods, a cost-benefit analysis, as return data becomes more complete, may prove these methods to be an economical means of expanding current hatchery production, particularly if "thinning" releases were used.

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Assessment of smolt condition for travel time analysis. Annual report 1989

The Water Budget is a volume of water used to enhance environmental conditions (flows) in the Columbia and Snake rivers for juvenile salmonids during their seaward migration. To manage the Water Budget, the Fish Passage Center estimates travel times of juvenile salmonids in index reaches of the main-stem rivers, using information on river flows and the migrational characteristics of the juvenile salmonids. This study was initiated to provide physiological information on the juvenile salmonids used for these travel time estimates. The physiological ability to respond to stressors was evaluated by measuring concentrations of plasma cortisol, glucose, and chlorides before and after a 30-s handling-stress challenge test. As in 1988, most groups responded satisfactorily to the challenge. The scope for response was compromised among two groups of juvenile chinook salmon that were trucked to release sites and in steelhead from one hatchery after unusual marking and transportation protocols were used. The development of smoltification was assessed by measuring gill Na+-K+ ATPase activity and plasma thyroxine concentrations. Mean ATPase activities of marked hatchery groups of juvenile chinook salmon and steelhead changed little during the month before release and rose sharply for about the first 20 d of the migration after release. Mean plasma thyroxine was highest during the first 20 d after release. Mean gill ATPase activity of spring chinook salmon from the migration-at-large peaked at about the 90th percentile of passage at Rock Island and Lower Granite dams, and at about the 50th percentile of passage at McNary Dam. Mean gill ATPase activity of wild steelhead was higher than gill ATPase activity of hatchery steelhead at Rock Island Dam, the Snake River Trap, and Lower Granite Dam, but not at McNary Dam. This was attributed to a time-dependent relationship between increases in ATPase activity and the number of days fish migrated before recapture. Correlations of gill ATPase activity and/or plasma thyroxine concentrations with condition factor, morphology, or skin guanine concentration may be useful as non-lethal indicators of smoltification for inclusion in a smoltification index. Prevalence of bacterial kidney disease in spring chinook salmon was generally higher than in 1988, ranging from 81-100% using an enzyme-linked immunosorbent assay (ELISA) method. Fish from Snake River hatcheries had more severe infections than those from mid-Columbia hatcheries. The percentage of fish with severe infections was lower at two downstream dams than at the Snake River hatcheries of origin, suggesting a bias in dam collection facilities or that these fish ceased to migrate, either of which could lead to biases in travel time estimates.

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Assessment of smolt condition for travel time analysis. Annual report 1988

Estimates of migration rates and travel times of juvenile salmonids within index reaches of the Columbia River basin are collected through the Smolt Monitoring Program for use by the Fish Passage Center. With increased reliance upon travel time estimates in 1988 by the Fish Passage Center, this study was implemented to monitor the biological attributes of juvenile chinook salmon Oncorhynchus tshawytscha and steelhead trout 0.- mykiss used for the travel time estimates, The physiological ability of fish to respond to stress was assessed by measuring levels of plasma cortisol, glucose, and chloride before and after a stress-challenge test. Most mid-Columbia and Snake river groups responded normally to the stress challenge exhibiting an increase in plasma glucose and cortisol and a slight decrease in chloride. Fish trucked to release sites were more stressed than those released directly from the hatchery, but most still responded to the stress challenge test normally. An abnormal or extreme stress response occurred when there were deviations from preferred protocol, disease problems at hatcheries, or when fish were trucked over long periods (7h). The development of smoltification was evaluated by measuring gill Na+K+-ATPase, plasma thyroxine, purines, and body morphology. Most groups were similar at the hatcheries but differed as the migration to McNary Dam proceeded. Gill ATPase activity increased 2-3 fold during the first 20 days of migration, after which it changed little. Fish with longer in-river travel times appeared to be more smolted than those which were in the river for a shorter period of time. The prevalence of bacterial kidney disease (BKD) in spring chinook salmon was evaluated using the enzyme linked immunosorbent assay (ELISA) and fluorescent antibody technique (FAT). Prevalence of BKD in groups tested using the ELISA method was as high as 99% at some downstream locations. A review of indices is presented as a guide, to the development of an index of smolt condition and preliminary data are presented. An index could be used as a tool to synthesize information on fish condition to assist with management and evaluation of the Water Budget.

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