Spatiotemporal variation in the spawning strategy of the Peruvian anchovy Engraulis ringens in northern Chile: Is the Peruvian anchovy developing a new strategy for survival?

Abstract

This study analyzed the spatiotemporal differences in the spawning of Engraulis ringens in northern Chile. We used three monthly time series of anchovy egg abundance collected over 26 years at three coastal stations in northern Chile (Arica, Iquique, Mejillones) and assessed the relative effects of hydrographic factors (i.e., temperature, salinity) and female reproductive conditions (i.e., Gonadosomatic Index [GI]) on egg abundance before and after the delay in the reproductive peak observed after 2009. We found significantly higher egg abundances in Arica during the first period (1998–2009). In contrast, during the second period (2015–2023), there were no significant differences between sites, and the spawning season became shorter, concentrating reproductive activity between August and October. The GAM model showed significant differences between periods and sites. Only in Arica, GI have a significant non-linear effect, while temperature had a linear effect on egg abundance. During the second period, GI had a significant linear effect on egg abundance that was not observed during the first period. Additionally, a shorter spawning season, smaller females and a reduction of the spawning stock biomass during the second period suggest a decline in spawning activity. We conclude that anchovies may have concentrated their spawning activity to increase their survival rates during the second period, which could explain the relationship between egg abundance and GI during this time, as well as a more organized spawning activity modulated solely by GI. This study represents the first analysis of the spawning strategy on a local scale, highlighting the urgent need for more regional management plans, especially under a global warming scenario that is affecting the natural cycles of marine species.