A study of the undersampling problem of fish larvae observed at the fixed stations in south Brazil

Abstract

The problem of daytime undersampling of larvae observed at two fixed stations made in the spawning ground of the Brazilian sardine is discussed. The size frequency composition of sardine is also discussed. The predominant species on the stations was the larvae of Sardinella brasiliensis. The larvae of Harengula spp., Scombridae, Bregmacerotidae, Ophidiidae were also collected, but not so abundantly. When compared to other larvae, the undersampling of sardine larvae during daytime was extremely high. Because the sampling was done both vertically and horizontally at one fixed station and marked undersampling was observed at both stations, it was concluded that the undersampling was caused by avoidance. It was necessary to take this problem into careful consideration for computation of larval abundance.