Comparison of the diel and spatial distribution patterns of ichthyoplankton and ichthyoneuston in the Southeastern Brazilian Bight

Abstract

Fish larvae were collected by neuston and bongo nets, in the Southeastern Brazil, during four oceanographie cruises (January 1980; January 1981; October 1981; and March 1982). The results are compared and analyzed in order to study the patterns of diel vertical distributions of fish larvae and to detect sampling problems. Larvae collected with neuston net were quite different in types and size composition, when compared with those collected with bongo net in oblique tows. Clear tendency of stratification in size composition at the uppermost layer can be observed on juveniles ( > 19 mm) of Sardinella brasiliensis which also showed day time avoidance. Most of the neustonic taxa were also caught in the deeper layers, although some groups, e.g. Mugilidae, Mullidae, and Gerreidae, were more abundant at the surface. Density of ichthyoneuston is much higher than those observed in the Northwest Atlantic and number of fish larvae collected during the day by neuston net exceeded that of night samples.