Coupling oceanic mesoscale events with catches of the Pacific sardine (Sardinops sagax) in the Gulf of California

Adult fish abundance depends on survival of early life stages, which are susceptible -among other factors- to environmental variability. Ocean mesoscale events (i.e. eddies, costal upwelling, thermal fronts, cold filaments) can be mechanisms of enrichment, concentration, retention and dispersal in marine environments with effects on survival of marine species early life stages. The Pacific sardine (Sardinops sagax) is an important fishery resource in the Gulf of California (GC), and it can rapidly respond to environmental fluctuations leading to dramatic changes in its abundance and fishery availability. This research analyzed the relationship of frequency and duration of different mesoscale processes with catches of S. sagax in the GC. Generalized additive models were applied to evaluate the effects of mesoscale events on the reproduction period, assuming they would reflect on catches several months later. The results show that eddies mostly affected the seasons with anomalous catches, where optimal duration of both types of eddies were responsible for the significantly high catches, while very high cyclonic and very low anticyclonic eddy duration led to significantly low catches. During the seasons with mean catches, high frequency of coastal upwelling and low persistence of Tropical surface sea water (TSW) northward intrusion were responsible for higher catches, while lower ones were associated to higher persistence of TSW intrusion and lower coastal upwelling frequency. A decreasing trend of coastal upwelling and filaments was detected, while the opposite occurred with TSW intrusion. These aspects should be considered in climate change scenarios because if sea surface temperature continues to increase, its implications in mesoscale processes could have consequences in the Gulf of California trophic dynamics.