Selectivity of bottom gillnet of southeastern Brazil

Abstract

Gillnet is one of the most widespread types of fishing gear on the Brazilian coast, greatly used by the small-scale fleet due to its low cost and easy handling. This study aimed to estimate the selectivity of gillnets by using length-converted catch curves for the main Osteichthyes species landed at Santos (SP) by gillnet fleet. Only landing data (length and weight) and production data were used, which are useful and easy to obtain, especially in countries with low budget for scientific research. The length at first capture (L_c50%) was compared to the length at first maturity (L₅₀) showing that only Micropogonias furnieri had a L_c50% very close to L₅₀; Menticirrhus americanus and Macrodon atricauda presented a characteristic celomatic cavity expansion during their pre-spawning period, which increases their maximum perimeter and changing the gear selectivity for both species; and Scomberomorus brasiliensis had the widest selection range, but all landed individuals already had length higher than the L₅₀. This method, combined with other biological data gathered from the literature, could be a good tool for fishery management. We suggest that temporal closed fishing areas and/or periods of gillnet usage suspension, and revision of technological aspects should be considered by management plans.