Postrelease Hooking Mortality of Rainbow Trout Caught on Scented Artificial Baits

Abstract
The postrelease mortality of rainbow trout Oncorhynchus mykiss caught on scented artificial baits was compared with postrelease mortalities of rainbow trout caught on traditional artificial flies. In all, 457 fish were captured on flies, 505 on artificial baits fished actively (ABA), and 511 on artificial baits fished passively (ABP) in five replicate experiments. Water temperature, fish length, time played, time out of water, hook location, leader treatment, and bleeding intensity were recorded for each fish captured. Mortalities were recorded daily over a 3-week holding period. Overall mortalities were 3.9% for fly-caught fish, 21.6% for fish caught on ABA, and 32.1 % for fish caught on ABP Differential mortality among gear types resulted largely from differences in the number of fish hooked in the gill arches or deep in the esophagus (critically hooked) in each group. Overall, critical bookings were 3.9% for the fly-caught group, 45.7% for the ABA group, and 78.3% for the ABP group. The Akaike Information Criterion, a model selection procedure, was used to develop a logistical regression model that best fit the mortality data. Parameters that reduced mortality probability include using flies rather than synthetic baits, hooking the fish in a noncritical location, and cutting the leader on critically hooked fish. In addition, as fish length increased, mortality probability decreased. Length of time played and length of time out of water contributed to mortality, as did increasing water temperatures and bleeding intensity.

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