The Effect of Illegal Harvest on Recreational Fisheries

Abstract

The degree of compliance with a fishing regulation can have a significant impact on the regulation's effectiveness. In this paper, we use a yield-per-recruit simulation model to evaluate the effect of poaching on legal harvest in sport fisheries. Two types of illegal harvest were considered: harvest of fish below the legal size limit and harvest of fish from catch-and-release fisheries. The results depict the degree of reduction in legal harvest in minimum-size fisheries with 0-100% (in 10% increments) illegal harvest. For brook trout Salvelinus fontinalis, the reduction in legal harvest ranged from 11% at 10% illegal harvest to 72% at 100% illegal harvest; these reductions ranged from 10 to 66% for northern pike Esox lucius, 8 to 57% for brown trout Salmo trutta, and 2 to 22% for largemouth bass Micropterus salmoides. In catch-and-release fisheries, illegal harvest reduces the number offish caught and released. Most ofthe benefits ofcatch-and-release regulations, in terms of increased numbers and sizes of fish, are lost when approximately 20% of large-sized fish (i.e., fish that would be legal in a minimum-size fishery) are harvested illegally. When all sizes of fish that can be caught by the fishing gear are illegally harvested, the benefits of the catch-and-release regulation are lost when illegal harvest reaches approximately 15%.