Aspectos da biologia de Eucinostomus argenteus Baird e Girard, 1855, Gerreidae, capturado no canal de Santa Cruz, Pernambuco

Abstract

This study describes biological aspects of the species Eucinostomus argenteus collected in the Santa Cruz Channel, city of Itapissuma (Pernambuco), with regard to reproduction and feeding habit. Totally, 1910 individuals -16.4% females, 5% males and 78.6% with indeterminate sex- were sampled monthly from October 2013 to September 2014. There was a predominance of females over males (3,3:1) (p<0,05). The length-weight relationship for females, males and pooled sexes showed positive allometry. The length at first sexual maturity (in total length, cm) (L50) was 8,31 for pooled sexes; 6,02 for males and 8,03 for females. It was observed that approximately 73% of the individuals were in length classes lower than the L50, with an average size of 4.97 cm (SD= ±0.94). Juveniles predominated in almost all months, representing 67% of the total. In the months of October / November 2013, there was the highest percentage of mature individuals, as well as the highest values of gonadosomatic index and gonadal index, representing a peak breeding for the specie. To diet composition were used the indexes of frequency of occurrence (%FO), numeric (%N), percentage weight (%P), and the Alimentary Index (%AI). The feeding strategy was defined by the graphical method of Costello. We used the Restricted Analysis coordinates Main (CAP) and PERMANOVA analysis to compare the diet between climatic periods and ontogenetic stages. The diet was based mainly on Cefalocordados, Teleosts and polychaetes. The component 1 (CAP1) showed an explanation of 88%, indicating the formation of groups 3, despite the observed overlap. While CAP2 explained 6% of the variation, contributing very little to interpretation of the scene. There were significant differences in all combinations evaluated period (PERMANOVA; R Global = 0.03834, p <0.05), ontogeny: Period (PERMANOVA; R Global = 0.16515, p <0.05), however the " ontogeny "represented a further explanation of these variables (PERMANOVA; p <0.05). The species presented a feeding strategy of an opportunistic benthivorous fish. We may indicate that the estuary of the Santa Cruz Channel is being used as a feeding ground for species of the family Gerreidae. The high number of individuals, especially in the juvenile stage, highlights the importance of the waters of the estuary of the Santa Cruz Channel-PE, as natural habitat and shelter for this kind of Gerreidae family. It is important to the regulation by the relevant public bodies, preventing the use of nets with small mesh openings, to avoid catching very young species.