Managing recreational fisheries through gear restrictions: The case of limiting hook size in the recreational fishery from the Balearic Islands (NW Mediterranean)

Enforcing a minimum legal fish size is a possible policy rule for managing recreational fisheries. However, success of such rules highly depends on an effective reduction of a mortality of released under-sized individuals. A very high post-release mortality is currently observed for certain species, which cancels any benefit of fish size limitation. Here we explore the effectiveness of limiting both gear characteristics and fish size. This management approach is aimed at biasing catches toward legal-sized individuals and minimizing the catches of under-sized fish. Specifically, size selection of fishes induced by hook size was evaluated for the near-shore boat recreational fishery from the Balearic Islands (NW Mediterranean). First, we evaluated the effects of different hook sizes on catch (number of individuals and species composition) and yield (biomass). Results showed how the number of captures was significantly reduced when using large hooks but bigger specimens and more valued species were caught. Moreover, the total yield remained unchanged, and the incidence of under-sized fish was significantly reduced. Second, the comparison of selectivity curves (i.e., logistic curves relating fish size and probability of being fished) corresponding to different hook sizes showed differences between two groups of species: those with small-mouth area, such as Coris julis or Diplodus annularis and those with larger mouth areas like Serranus scriba. Small-mouth species tend to display larger selectivity: the curves for each hook size are steeper, and there is more of a split between the curves. The results presented here motivated the authority in charge of managing the recreational fishery at the Balearic Island to stipulate a minimum legal hook size. The trade-offs of this rule between angler interest and conservation goals are discussed.