Spatial and temporal variability of the two main catched species of an artisanal trap fishery in an oceanic island

Abstract

This study analysed the catches of trap fishing in the Canary Archipelago, NE Atlantic Ocean. This study was conducted from October 2016 to September 2017, April to November 2018 and September 2020, in five ports (San Cristóbal, Taliarte, Castillo del Romeral, Arguineguín and Mogán). The primary gear were traps with small mesh size (31.6 mm) and large mesh size (50.8 mm). A total of 2587 small mesh size traps and 141 large mesh size traps were analysed from 20- to 130-m depth. The main target species were Dentex gibbosus and Stephanolepis hispidus. Catches of traps with large mesh size showed D. gibbosus above first maturity and S. hispidus in small mesh size traps. Both species exhibit larger specimens during reproductive periods. The most effective traps for D. gibbosus (large mesh) were located on the western coast (>30-m depth), with the highest catch per unit of effort (CPUE) in Mogán (857.7 g trap−1 day−1). The most effective traps for S. hispidus (small mesh) were located in southern areas, especially in sandy habitats (124.9 g trap−1 day−1 in Castillo del Romeral, 102.9 g trap−1 day−1 in Arguineguín). The highest catchability of D. gibbosus was observed in April (CPUE of 962.8 g trap−1 day−1), and the highest catchability of S. hispidus was found in June (CPUE of 165.9 g trap−1 day−1). The traps with small mesh size showed a great selectivity of sizes for S. hispidus; though high catch rates of immature specimens of D. gibbosus pose a threat to species conservation. The management recommendations' proposed measures include revising minimum catch sizes for both species. Additionally, we suggested depth limitations for mesh sizes of traps. The study highlights the need for new management strategies to ensure the conservation of targeted demersal species, with special emphasis on addressing the threat posed by small mesh sizes to immature D. gibbosus. The findings provide valuable insights for adapting fishery management practices to sustainably conserve the targeted species in the Canary Archipelago.