Impact of catch-and-release on behaviour, recovery and fate in two fish species: a before-after-control-impact study in a shallow lake.

Catch-and-release (CR) is widespread in recreational fisheries, but can affect behavior and survival of released fish. We used whole-lake high-resolution acoustic telemetry and a Before-After Control-Impact Paired Series design to study post-release mortality and movement activity in Eurasian perch (Perca fluviatilis) and common carp (Cyprinus carpio) in a natural lake. Fish caught with hook-and-line and uncaptured controls were monitored for six months after CR. We found no significant hooking mortality in either species after accounting for natural and surgery-based mortality of controls. Sublethally, movement activity declined significantly in perch, with recovery to pre-capture levels taking a mean of seven days; 36% of significantly impacted perch (4 of 11 captures) had not recovered by the end of the 10-day monitoring period. Carp showed weaker and more variable responses. Under similar conditions as examined here (e.g., shallow capture depth and hooking, moderate temperature), CR is suited to reduce fishing mortality and maintain populations despite heavy fishing pressure, but this comes at the cost of a multi-day, reversible behavioral impairment to the individuals that are caught and released.