Gillnet selectivity for the spotted rose snapper (Lutjanus guttatus) and the amarillo snapper (Lutjanus argentiventris) in Navidad Bay, Jalisco, Mexico

Gillnet selectivity for Lutjanus guttatus and L. argentiventris in Navidad Bay, Jalisco (Mexico), was estimated using monthly samples. Gillnets of 7.62- and 8.89-cm mesh size were used for the experimental design; 475 organisms of L. guttatus and 134 organisms of L. argentiventris were caught. The results show that the organisms caught with the 8.89-cm mesh were on average 4 cm larger and 100 g heavier than those caught with the 7.62-cm mesh. For L. guttatus, the optimum length (100% retention probability) was 29.1 cm for the 7.62-cm mesh and 33.9 cm for the 8.89-cm mesh; for L. argentiventris, the optimum length for the 7.62-cm mesh was 28.9 cm and for the 8.89-cm mesh, 33.7 cm. In both cases the catch mode corresponds to the calculated optimum length. The gillnet of 7.62-cm mesh caught the largest abundance in terms of number of individuals and biomass; however, the 8.89-cm mesh assures the catch of organisms that have reached first maturity length