Diversidade e produção da ictiofauna desembarcada na ilha de São Luís do Maranhão no início do período chuvoso

Abstract

Fishing is an activity of great importance to the world's population, as it provides a high source of food and income. The coast of Maranhão is home to 278 fishing communities. The Golfão Maranhense region has a high density and biomass of fish. This study assessed the diversity, abundance and production of the ichthyofauna caught by subsistence fishing in the estuary and commercial fishing on the island of São Luís. The samples were collected from December 2023 to February 2024. Subsistence fishing was carried out using different gear, including trawls, gillnets and tarrafas, with meshes ranging from 1.5 to 2.5 cm between opposite knots. In addition, 384 fishing landings were monitored in 10 ports. Species that were caught in excess of 50 individuals were recorded with seven morphometric measurements, using a pachymeter and ichthyometer, and weight with an analytical scale. Richness was determined by the number of species per sample. The Pielou index was used to define equitability, and diversity was defined using the Shannon index. Correlations between lengths were of the linear type and the power equation was used for the weight-length relationship. The frequency of occurrence and abundance per species were also estimated. The ichthyofaunal community from subsistence fishing was represented by 11 orders, 20 families and 43 species, making up a total of 806 individuals analyzed. The families that contributed most to richness were Sciaenidae (6), Carangidae (5), Ariidae (4) and Mugilidae (4). However, in terms of the abundance of individuals, the Gerreidae taxon had 167 fish sampled. With regard to species of economic interest, 27 species were found to be common in subsistence and commercial fisheries. Shannon's diversity index showed higher values in December and January. The equitability index was higher than 0.5, indicating uniformity in the abundance of species. Weight-length correlations were strongly positive, with positive allometry for most species. The richness of the species landed in the ports was 67 species, with yellow hake and corvina hake present in nine of the ports monitored. The production monitored in January was 31,713.7 kg for nets and 6,167 kg for longlines. The port with the highest production was the port of Braga, in the municipality of Raposa.