Spatial-temporal Variations of Discarded Ichthyofauna from a Small-scale Shrimp Fishery: Influence of Ecological Patterns in a Yucatan Coastal Lagoon

Spatial-temporal variations of discarded catches associated with a shrimp-small scale fishery from the Celestun lagoon, Yucatan, Mexico, were analyzed throughout seasonal and spatial (inner, middle, and external estuarine zones) physicochemical gradients to observe the influence of ecological patterns on discarded ichthyofauna. Differences in abundance, biomass, composition, and physicochemical variables between seasons and among zones were tested using a two-way ANOVA and an analysis of dissimilarity, respectively. The best subset of environmental variables (BIOENV) function was used to observe the influence of physicochemical gradients on the discarded fish community. A total of 1611 individuals belonging to 36 species of discarded fish were identified, with mostly an abundance of juveniles occurring for the following species: Achirus lineatus, Archosargus probatocephalus, Cynoscion nebulosus, Eucinostomus gula, Floridichthys polyommus, Lagodon rhomboides, Lucania parva, Mayaheros urophthalmus, and Sphoeroides testudineus. Hence, the data shows a strong selection pressure on juvenile fish. Significant differences in abundance, species composition, and physicochemical variables were observed between seasons and zones. Results from the BIOENV indicated that temperature, salinity, and pH gradients, generated by underground freshwater discharges, influenced the spatial-temporal variations of discarded ichthyofauna from the Celestun lagoon. Furthermore, reproductive seasons, and capabilities to tolerate salinity concentrations also spatially structures a discarded fish community. The results showed the ecological complexity in which fish discards occur, in addition, suggesting measures to reduce discards by including ecological and social aspects to maintain the sustainability of this artisanal shrimp fishery.