Abstract
Variability in community (richness, diversity and evenness) and population (size structure) attributes of discards was evaluated in a shrimp fishery in Celestun Lagoon, Mexico, in different climatic seasons and hydrological zones. Sampling was conducted using two bottom nets with different mesh size codends: 1.3 cm (used in the fishery) and 2.5 cm. Although the shrimp:discard ratio was 1:1 in both cases, total biomass and abundance with the 1.3‐cm mesh size were, respectively, 4.6 and 1.8 times higher than with the 2.5‐cm mesh size. This result was consistent in time and space. Discards were dominated by fishes [60% in 1.3‐cm mesh size and 96% in 2.5‐cm mesh size, mainly Cichlasoma urophthalmus (Günther), Eucinostomus gula (Quoy & Gaimard) and Lucania parva (Baird & Girard)] and shellfishes (40% in 1.3‐cm mesh size and 4% in 2.5‐cm mesh size, mainly Palaemonetes spp. and Callinectes spp.). The highest discards were registered the nortes season with both mesh sizes. The 1.3‐cm mesh size retained significantly smaller sizes than the 2.5‐cm mesh size in six of the eight most important species. An increase in mesh size, together with a fishery closure during the nortes season, are suggested to mitigate the impact of the fishery on the discarded fauna.