Successful recovery of the physiological status of coho salmon on board a commercial gillnet vessel by means of a newly designed revival box

Successful application of fish-revival techniques in commercial fishing pri or to release of nontarget species requires clear evidence that recovery de vices do indeed improve physiological status and minimize postcapture delay ed mortality. This study provides such evidence for a newly designed recove ry box (Fraser box) that assisted gill ventilation. Immediately after captu re by gillnet, adult coho salmon (Oncorhynchus kisutch) were in a state of severe metabolic exhaustion and stress, based on a comprehensive analysis o f plasma and muscle tissue. However, when placed in a Fraser recovery box f or 1-2 h, both lethargic and vigorous fish showed significant metabolic rec overy and their ability to swim was also quickly restored. An emphatic demo nstration of the benefit of the Fraser box was the successful revival of > 90% of fish that appeared dead at capture. Furthermore, postcapture delayed mortality was only 2.3% after a 24-h observation period. Therefore, in the context of commercial salmon gillnet fishing, revival of nontarget coho sa lmon in a Fraser box, in combination with a soak time (total time the gilln et is in the water) less than or equal to 70 min and careful fish handling to minimize physical trauma, could improve physiological status, restore sw imming ability, and markedly reduce postcapture delayed mortality.