Angling gear avoidance learning in juvenile red sea bream: evidence from individual-based experiments

Angling gear avoidance learning is a possible factor that contributes to the vulnerability of caught-and-released fish to angling. Whereas past studies suggested angling gear avoidance learning, they were based on large-scale experiments on groups of fish and unable to verify learning accurately. Details of avoidance learning are also unclear. The present study investigated angling gear avoidance learning through a series of individual-based experiments using red sea bream (Pagrus major) juveniles. Fish avoided angling gear after only one or two catches while showing feeding motivation for pellets, representing avoidance learning for angling gear. Most of the experienced fish avoided krill attached to a fishing line, but not krill alone or pellets presented near the angling gear. Experienced fish were less vulnerable to angling than control fish. Approximately half of the experienced fish kept the memory of angling gear 2 months after learning. The learning effect through the catch-and-release procedure would reduce catchability and the value of fishery-dependent stock assessments.