Investigating climate-driven variability of a small pelagic fishery off the Indian west coast using a population dynamic model

Predicting the population and landings of small pelagic fish in key fishing grounds has significant economic and fishery management value. This is particularly crucial for a country like India, where fisheries contribute up to 7% of agricultural income, and pelagic finfish account for 54% of the marine catch. Climate variability imprints distinct signatures on the annual landing variability of India's coastal small pelagic fisheries (Hamza et al., 2021a, b, 2022), which could provide crucial support for such predictions. Leveraging the strong dependence of oil sardine (Sardinella longiceps) landings on climate variability, a bioenergetic-driven population model, termed the Bioenergetics Indian Ocean Fishery Model (BIOFIM), has been developed that links climate variability to total biomass. This model successfully reproduces the interannual variability in oil sardine landings along the west coast of India over the past 53 years (1965–2017) with appreciable accuracy. Among the environmental drivers representing large-scale climate variability, atmospheric pressure emerges as a significant factor influencing model performance, followed by sea surface temperature and air temperature. Atmospheric pressure anomalies, which influence the winds and underlying ocean currents, become a key predictor in the model. Further, the model investigations revealed that the sardine fishery remains sustainable within ±15% of the mean when the mortality rate changes by ±10%. However, fishing by 40–50% may lead to a severe decline in sardine populations along the southwest coast of India, posing a critical threat to the sustainability of the fishery.