http://www.wildtroutstreams.com/Catc...guidelines.pdf

The impact of mortality caused by catch-and-release practices is often underestimated by
both anglers and fishery managers. From a review of 118 catch-and-release studies (Appendix
1), which, in total, involved over 120,000 fish, the average mortality associated with catch-andrelease
angling was 16.2%. Thus, while many anglers may assume that by practising catch-andrelease
they are having no impact on the fish population, a significant number of released fish
may die. Additionally, many anglers will continue to fish after they have caught their limit under
the premise that they will release all further fish caught, however they often do not take into
consideration the number of fish which will inadvertently be killed as a result of this practice.