Variabilidad espacial y temporal de huevos y larvas de Strangomera bentincki y Engraulis ringens, asociados a la desembocadura del río Itata, Chile

Abstract

This study assesses the spatial and temporal variations in eggs and larval distributions of Engraulis ringens and Strangomera bentincki during their peak and secondary spawning periods, in the zone adjacent to the Itata River mouth, Chile. The information on abundance and distribution of the early life stages of both fish species was obtained from seven oceanographic cruises performed out between 1996 and 2005. The abundance and distribution of eggs and preflexion larvae of both species and, in order to detect potential variations in abundance was analyzed. Our results showed that eggs of both species tended to aggregate at the coast. The spatial extensions of preflexion larvae were broader than that of eggs of both species, along a coast- to- ocean direction. The distribution of the early life stages of both species over the continental shelf off the Itata River mouth was variable inter-annually. These egg and larval abundances showed significant variations among years and the eggs abundance was higher than of larvae. The highest egg and larval abundances occurred at salinities between 32 psu and 34 psu. However, occasionally it was possible to find aggregations in lower salinities (20-24 psu) in the nearby zone of the Itata river mouth. The area contiguous to the river mouth, however, showed low abundance of egg and larvae during the period studied.