Unexpected diversity in the diet of Doryteuthis sanpaulensis (Brakoniecki, 1984) (Mollusca: Cephalopoda) from the southern Brazilian sardine fishery identified by metabarcoding

Abstract

Growing fishing pressure worldwide has led to an increase in the exploitation of cephalopod products in fish markets where these taxa were not traditionally consumed. Squid catches have surged to meet that demand, yet for many species little is known about their role in food webs. Doryteuthis sanpaulensis is an important squid species in southeastern Brazilian fisheries. Despite many previous efforts at morphological analysis of its diet, few demersal and benthic species of fishes, crustaceans and mollusks have been identified to species level because the food is consumed in small digestible fragments. Here we used metabarcoding to analyze the diet of adult D. sanpaulensis caught as bycatch in the southern Brazilian sardine fishery. MOTUs generated from COI amplicons were assigned to taxa by matching against the NCBI nt database. Fishes constitute the majority of the diet of the analyzed samples. Considerable variability in the relative read abundance and frequency of occurrence of prey items across samples indicates the importance of increased sample sizes in analyses investigating ontogenetic, spatial, or temporal variation in diet. The results elucidate the rich diet of D. sanpaulensis off the Brazilian coast, and specifically that its varied diet includes more neritic diversity than previous studies have indicated.