Squids caught by shrimp trawlers off the coast of Sergipe, northeastern Brazil

Abstract

Shrimps are one of the main fishery resources caught in waters off the state of Sergipe and accounted for about 32.3% of the total catch in 2013 (Thomé-Souza et al., 2014). One of the main problems associated with shrimp trawlers is the impact of repetitive bottom trawling (Meenakumari et al., 2008) and the capture of a high number of juveniles of fish species of commercial interest, but also gastropods, sea stars, crabs, and cephalopods (Alverson et al., 1994;Keunecke et al., 2007;Silva Júnior et al., 2019).Cephalopods are not economically exploited in the waters off Sergipe (Thomé-Souza et al., 2014). However, there are a few localities in northeastern Brazil where cephalopods, especially octopuses, are targeted by commercial fisheries (Haimovici et al., 2014;Lima et al., 2021). In the southeastern and southern regions of Brazil, cephalopods have a considerable fishing production when compared to the northeastern region. Previous efforts, such as the REVIZEE program (Programa de Avaliação do Potencial Sustentável de Recursos Vivos na Zona Econômica Exclusiva do Brasil -Program for the Assessment of the Sustainable Potential of Living Resources in the Brazilian Exclusive EconomicThe objective of this study was to identify the squids caught by shrimp trawlers in Sergipe and to describe their populational structure. Four samples were obtained monthly from commercial trawlers based in Pirambu-Sergipe (May/2015-May/2016). Each squid found was separated, identified, weighed individually (wet weight -WW in g) and had its mantle length (ML; cm) and total length (TL, including tentacles; cm) measured. One specimen of Doryteuthis pleii was captured (23.3 cm ML mature male), as well as 152 specimens of Lolliguncula brevis (1.5˗6.7 cm ML). The linear relation between TL and ML of L. brevis was TL=5.1173+2.6190ML (positive allometry) and the power relation between WW and ML was WW=0.1453ML 2.5353 (negative allometry). For L. brevis, there were two cohorts in the area during the period analyzed. Studies on the biology of cephalopods are scarce in northeastern Brazil, especially considering that these species are present in the bycatch of shrimp fishing and that the global conservation status of L. brevis is data deficient (DD) according to the International Union for Conservation of Nature (IUCN).