A Short Review of Fisheries Bycatch and Bycatch Estimation

As fishing gears and methods have become more advanced and pressures from commercial, artisanal, and sport fisheries have increased so has concern for the inadvertent capture of non-target animals and of unwanted age and size classes of target populations.  This proportion of the catch, often called "bycatch”, diminishes wild populations with potentially widespread population-level effects.  It can also remove forage for higher trophic levels and, due to the discarding of large numbers of unwanted dead or dying animals overboard, produce other undesirable ecosystem-scale effects such as sea-bottom fouling.

Strategies have been developed to reduce or otherwise mitigate bycatch effects including season and range reductions and closures, limits on bycatch take and disposal, and modifications of fishing gears and methods to increase gear specificity, reduce bycatch, and increase the escapement and survival of unwanted non-target animals.  Sometimes the modifications of fishing gear and methods have been developed by the fishers themselves based upon their familiarity with and understanding of their fishery and the equipment involved in it.

A short introduction to bycatch-related problems and a few examples of attempted mitigations in both net and hook-and-line fisheries in both freshwater and marine systems will be presented.