Distribution of Bluefish (Pomatomus saltatrix) Larvae along the Continental Shelf off Southern Brazil

Abstract

Data from ichthyoplankton surveys between 1980 and 1990 are used to describe the distribution of bluefish (Pomatomus saltatrix) larvae along the continental shelf off southern Brazil (24º-35ºS). Only 46 larvae in 9 stations were found in 1026 oblique and horizontal tows taken with a 330 pm-mesh Bongo net. Larvae ranged in size from 3 to 10 mm, with the larger larvae distributed close to shore. There were no significant differences in size between larvae found in the northern and southern regions of the shelf. However, there was evidence of a gradual northward displacement of larval abundance towards winter. About 85% of the larvae occurred in the southernmost region of the shelf (below 32ºS) in January and February (summer), and the remaining larvae were caught further north from March to August. This pattern of larval distribution could be attributed to the northwards retreat of warmer (> 20ºC) and more saline (> 34) Brazilian coastal waters from the region. Results from this study suggest that bluefish spawn over a protracted period, following the seasonal displacement of Brazilian coastal waters along the continental shelf off southern Brazil, a pattern that is also consistent with the spawning migration proposed for bluefish in the north-western Atlantic.