Phenological mismatch contributes to anchoveta landings collapse under El Niño and climate change in the Peruvian upwelling system

The Peruvian upwelling system, crucial to the global fisheries network, experiences strong interannual variations that deeply affect fish yields during El Ni & ntilde;o events. To understand these fluctuations, we used a regional physical-biogeochemical model (CROCO-BioEBUS) simulation from 1980 to 2015, focusing on the factors leading to decreased fishing yields during El Ni & ntilde;o periods. Our results suggest that, in non-El Ni & ntilde;o years, plankton blooms coincide with the critical period between hatching and first-feeding, ensuring optimal prey conditions for early-stage fish larvae. However, our analysis of the severe El Ni & ntilde;o events of 1982-1983 and 1997-1998 showed that abnormal warming disrupts this synchrony, leading to a mismatch between plankton blooms and early-stage fish larvae, potentially impacting survival rates of fish larvae and, by extension, fishing yields. Extending our analysis to the effects of long-term temperature change-global warming-under two climate change scenarios (SSP1-2.6 and SSP5-8.5), we observed varying shifts in the timing of fish spawning, which affect the synchronization between plankton blooms and early-stage fish larvae. A mild temperature increase, as projected from the SSP1-2.6 scenario, could extend the fish spawning season to over half of the year. Depending on when the fish spawn during this period, larvae might face similar feeding conditions to current normal years if spawning takes place during austral summer, or they might face reduced food availability if spawning takes place in austral winter. Conversely, a higher temperature increase, as projected from the SSP5-8.5 scenario, could shorten the spawning season and displace it to about half a month during the austral winter, coinciding with worse feeding conditions and potentially having a disastrous impact on fisheries. This study underscores the need to understand and anticipate the complex interplay between climate events and marine ecosystems, highlighting the pivotal role of ...