Early warning of critical transition in east Venezuela’s Sardine (Sardinella aurita, Valenciennes 1847) Fishing Area.

Global warming is affecting the thermal tolerance of marine species and disrupting fisheries. Venezuelan sardine ( Sardinella aurita, Valenciennes 1847) fisheries are facing a decline possibly linked to climate change. Understanding the temperature trends along coastal areas versus the open ocean is crucial for effectively managing these sensitive species. This study examines Sea Surface Temperature (SST) variability in Venezuela's Sardine Fishing Area and Exclusive Economic Zone (EEZ), detecting early warning signals (EWS) of critical transition. Using MODIS SST data (2002–2023), we assessed variability in both zones, calculating standard deviation (SD) and first-order autoregressive coefficient AR(1) as indicators. Results showed that while minimum SSTs were similar and stable, mean and maximum SSTs were higher in the EEZ. Coastal waters exhibited greater intra-annual mean temperature amplitude (4.34±0.7°C) than the EEZ (2.94±0.41°C), possibly driven by upwelling and thermal stratification. Minimum and mean SST SD remained stable, while maximum SST SD fluctuated, with a marked increase in coastal area, suggesting growing environmental pressures. AR(1) analysis reveals strong persistence increasing over time in minimum and mean SSTs (0.65 - 0.85), indicating reduced system resilience and proximity to a tipping point. Maximum SST AR(1) decreased, implying greater random variability in future extreme warming events. Unpredictable peak sea surface temperatures (SSTs) could destabilise S. aurita stocks, affecting their distribution, reproduction and survival. The decline in resilience and predictability will make adaptive management efforts more challenging. The study underscores the urgent need for further research into SST predictability and its ecological consequences.