Biologia reprodutiva e ecologia trófica do peixe Larimus breviceps (Perciformes: Sciaenidae) no litoral da Paraíba

Abstract

The shorthead drum Larimus breviceps is one of the main bycatch species of the shrimp fisheries in Brazil. However, studies addressing the biology and fisheries impacts on this species are still scarce (e.g., macroscopic, and microscopic ovarian maturation, oocyte development, seasonal variation in the diet, morphometric attributes, isotope analysis). Here, we describe the main aspects of the reproductive biology and the feeding ecology of L. breviceps on Paraíba, northeast Brazil. A total of 970 individuals (549 females and 421 males) were caught between December 2016 and November 2017 through a beach seine. The total length (TL) varied from 4.2 to 23.0 cm. Females dominated over males (1 female: 0.77 male). The gonads were described by macroscopic and microscopic analysis. The ovaries were composed by oogonia, pre-vitellogenic, vitellogenic, mature and atretic oocytes. Thereafter, the following stages were thus defined for females: immature, initial development, advanced development, mature and regressing. The period of highest reproductive activity occurs between November and March and immature individuals occur throughout the year. The mean length at first maturity (L50) was 11.1 cm TL. To the feeding ecology study, a subsample of 419 stomachs were analyzed. The total length (TL) varied between 6.3 and 19.2 cm. Nine feeding categories were defined for L. breviceps. Sergestidae was characterized as the main prey (IAi=83%). The diet composition displayed a different pattern for juveniles and adults. Significant differences were found for peduncle flatness index and body flatness index in 49 individuals (27 juveniles and 19 adults); indicating that adults are faster swimmers than juveniles. A total of 40 individuals (dry season = 20; rainy season = 20) were selected for stable isotope analysis. Differences were found in δ13C values for different size classes in the dry season, with juveniles feeding on preys with higher δ13C levels than the adults. The shorthead drum had a trophic level between the third and fourth position, classifying the species as a carnivore predator. The information provided here contributes to the overall knowledge of this species and may be useful for further development of management practices that ensure sustainability of marine species exploitation.