Physiological status of coho salmon (Oncorhynchus kisutch) captured in commercial nonretention fisheries

The physical, hematological, and metabolic condition of 303 adult coho salm on (Oncorhynchus kisutch) was examined following capture with three commerc ial fishing gear types (seine, troll, and gill net) and a variety of method s. All fish arrived onboard in a state of severe metabolic exhaustion, and physiological differences among gear types and fishing methods were few and relatively small. Fish showed less physiological disruption with a brailin g versus a ramping method of seine fishing and with a 30-min versus a 60-mi n net soak time for gillnet fishing. The visual ratings of physical conditi on (nonbleeding, vigorous, and lethargic) correlated significantly with hem atocrit, plasma osmolality, plasma lactate, and plasma sodium. Fish placed in recovery boxes for 30-60 min onboard fishing vessels did not show the ex pected metabolic recovery; only plasma potassium recovered significantly. H owever, plasma lactate levels declined significantly for 125 fish placed in a net pen for 24 h, suggesting that metabolic recovery was possible after commercial capture. Because of a concern that the current recovery box desi gn does not effect optimum recovery, we recommend that future experiments t est a better-designed recovery box that orients fish into flowing water.