Humboldt-Universität zu Berlin - Albrecht Daniel Thaer-Institut für Agrar- und Gartenbauwissenschaften

Absence of Handling-Induced Saprolegnia Infection in Juvenile Rainbow Trout with Implications for Catch-and-Release Angling

Catch-and-release angling is common in recreational fisheries. During handling and dehooking, fish are subjected to stress and dermal injuries, which may result in infections by pathogens after the fish is released. The objective of this study was to evaluate the consequences of common handling practices used by anglers on the postrelease behavior and fate, particularly the susceptibility to disease, of undersized Rainbow Trout Oncorhynchus mykiss. Behavior immediately following capture and subsequent release of fish was examined in a 40-L container, and long-term fate was studied for 2 weeks in tanks incubated withSaprolegnia parasitica zoospores. Trout were behaviorally impaired as indicated by the ease of being netted following the simulated fight associated with catch and release, but there were no further behavioral impacts due to subsequent handling. None of the Rainbow Trout developed fungal infections nor was any significant mortality observed after 2 weeks; only 1 out of 137 fish died. Our data indicate that juvenile hatchery-reared Rainbow Trout have a high resilience to Saprolegniainfection handling-induced stress.