MATURATION AND GILL-NET SELECTIVITY OF 2 SMALL SEA BREAMS (GENUS DIPLODUS) FROM THE ALGARVE COAST (SOUTH PORTUGAL)

Diplodus annularis and Diplodus bellottii, two species of small sea br eams from the Algarve coast (south Portugal), were studied to obtain i nformation on the spawning period, first maturity, weight-length relat ionship and gill-net selectivity curves. These species are important i n local gill-net catches, and there is no information on their biology and selectivity in the Algarve waters. Spawning lasts for 6 months. T otal length (TL) at first maturity for females was 13.4 cm in case of D. annularis and 11.4 cm in case of D. bellottii. The relationships be tween weight and length were W = 0.0132 TL3.096 for D. annularis and W = 0.0093 TL3.193 for D. bellottii. The Sechin method was used to esti mate gill-net selectivity curves. The estimated selectivity curves cor respond closely to the catch curves of the legal mesh size (60 mm), bu t were narrower for the other meshes. D, annularis and D. bellottii wi ll be caught using the legal mesh size in the following length ranges: 13-19 cm and 11-19 cm. (C) 1998 Elsevier Science B.V. All rights rese rved.