Early stages of anchovy: abundance, variability and larval condition at the fixed coastal station EPEA between 2000-2017

Abstract

Densities of eggs and larvae of Engraulis anchoita and the nutritional condition of larvae were analyzed in the fixed sampling station (EPEA) in the period 2000-2017. These variables were analyzed seasonally and trends over time were determined. Ichthyoplankton samples were collected by oblique trawls using Bongo nets with 300 μm of pore mesh and fixed with formaldehyde 5% in seawater. Six morphometric variables were measured to estimate the nutritional condition of larvae. The developmental stage of each specimen was also determined. The highest mean value of egg density was detected in the October-December period, with a secondary mode in August, followed by one in March. Larval density presented a mode in October. Autumn and spring were the most favorable seasons for larval condition while winter proved to be the least favorable one. An increase in food availability during autumn and spring due to primary and secondary production peaks could explain the high nutritional condition and growth values observed in these seasons at the EPEA. No changes in trends of variables over time were detected. The integrated study of density and nutritional condition of E. anchoita larvae allows the determination of favorable breeding periods for the species, while the continuation of the long term study will allow evaluating possible effects of climate change in the early life stages of this species.