Stress‐induced changes in plasma cortisol, glucose, and chloride were more extreme in wild rainbow trout Salmo gairdneri than in hatchery‐reared fish subjected to confinement in a net and to electroshock. During 12 h of net confinement, plasma cortisol increased from resting levels of 10 ng/mL to 480 ng/mL in wild fish, and from 2 ng/mL to 155 ng/mL in hatchery fish. Plasma glucose was also higher in wild fish, increasing from 55 to 284 mg/dL, versus an increase from 58 to 196 mg/dL in hatchery fish. Plasma chloride decreased from resting levels of 132–135 meq/L to 53 meq/L in wild fish (and it continued a decline to 33 meq/L during the first 24 h after confinement), but only to 102 meq/L in hatchery fish. Both wild and hatchery‐reared fish required more than 24 h after they were removed from the net to recover resting levels of plasma constituents. Plasma concentrations of cortisol, glucose, and chloride were less altered in response to electroshock than they were in response to net confinement. One hour after galvanonarcosis, plasma cortisol concentrations in wild fish peaked at 234 ng/mL and remained moderately elevated for 4 d; cortisol in hatchery fish peaked at 70 ng/mL within 0.5 h of the electrical stimulus and then returned to resting levels within 1 h. No substantial changes in plasma glucose or plasma chloride occurred in either the wild or the hatchery‐reared rainbow trout after galvanonarcosis.

Brief anesthetization with 50 mg/L buffered MS-222® (ethyl m-aminobenzoate methanesulfonate) of yearling chinook salmon (Oncorhynchus tshawytscha) during mild handling caused no change in plasma cortisol concentrations compared with levels in non-anesthetized fish. Prolonged exposure (180 min) to a depressing dose of buffered MS-222® (25 mg/L) elevated cortisol more than an immobilizing dose (50 mg/L), while 100 mg/L was lethal within 30 min. Fish anesthetized (50 mg/L MS-222®) during a severe 30-min handling stress had significantly lower mortality than controls to a second handling stress applied when the fish were no longer anesthetized. Anesthetization during the first stressor also prevented the cortisol stress response evident in the control fish. Anesthetic (with or without buffer) administered before initial capture was most effective at increasing survival during a second stressor, while anesthetic supplied after initial capture may have been slightly less effective. A 0.5% NaCl solution supplied after capture was less effective than any anesthetic treatment in increasing future survival, but was better than no treatment. Saline treatment did not attenuate the cortisol stress response. A rapid method of plasma sample preparation for competitive protein binding assay of cortisol was developed. Key words: chinook salmon, cortisol, stress, anesthetic, cortisol assay, survival

A small, second‐order stream in the southern Appalachians was sampled every 2 months from September 1978 to October 1979. The 1.5‐km study segment was divided into 50, 30‐m sections grouped into three areas: A downstream area with only rainbow trout Salmo gairdneri; a middle, mixed‐trout area; an upstream area with predominantly brook trout Salvelinus fontinalis. Although a few fish of both species exhibited substantial movements, the majority of fish moved less than 30 m either upstream or downstream. Growth rates of both species were approximately equal until the spring of their second year, when rainbow trout outgrew brook trout and thereafter maintained a size‐at‐age advantage. Rainbow trout, particularly the 1978 cohort, dominated trout production in the stream. Even in the brook trout area, where the density of 1978 cohort brook trout was twice that of 1978 cohort rainbow trout, rainbow trout outproduced brook trout by 1.20 g/m2 to 1.14 g/m2. Declining mean biomass of older fish of both species indicates high winter mortality. This, accompanied by slow growth of older fish, resulted in very few fish of either species entering the legal fishery. Received November 27, 1981 Accepted April 24, 1983

We assessed salmon id production in summer in a second-and third-order montane stream in eastern Tennessee in 1987. We sampled three stream sections, one containing exclusively brook trout Salvelinusfontinalis. one containing exclusively rainbow trout Oncorhynchus mykiss. and a third with a mixture of both species. Population estimates for July and October 1987 revealed reductions in biomass over the 4-month period that ranged from 31 to 49%, whereas population densities declined by 32-46% during the same period. Total net production during the 4-month period was low and ranged from 0.38 to 0.45 g/m 2 . From June through September, the mean number of prey items per stomach ranged from 4.2 to 29.9, whereas the mean relative weight of stomach contents ranged from 0.12 to 1.34 mg dry weight per gram wet weight offish flesh. There was a strong positive correlation between the mean relative weight of stomach contents and the mean condition factor for a given date. Calculated energy intake was below the level necessary to provide energy for maintenance metabolism.

Plasma corticoid concentrations in juvenile chinook salmon (Oncorhynchus tshawytscha) netted and confined in a small live-cage rose from approximately 100 ng/ml to about 500 ng/ml in 24 h, then fell to 250 ng/ml at 48 h. In juvenile chinook salmon dip netted into a bucket containing aerated water and sampled serially at 90-s intervals, plasma corticoids increased from < 10 ng/ml to approximately 100 ng/ml in 20 min. In juvenile cutthroat trout (Salmo clarki clarki) acclimated to 13 C and subjected to a rapid increase in water temperature to 26 C, plasma corticoid concentration increased from about 20 ng/ml to 70 ng/ml in 25 min and remained elevated for more than 3 h. Juvenile cutthroat trout acclimated to diurnal temperature cycles (13-23 C) had no sabstantial changes in plasma corticoid concentration throughout the cycles. Juvenile cutthroat trout acclimated to 23 C had •;he same initial corticoid concentration as cutthroat trout acclimated to 9 C. When both groups were subjected to identical netting and confinement, the corticoid concentrations in fish from the two temperatures responded in a similar fashion until 70 rain of confinement when trout from the warmer water failed to maintain increasing corticoid concentrations.