A sudden surge of juvenile Indian Oil sardines along Kerala’s coast in 2024 was driven by climate-induced monsoon trends according to a new study by the ICAR-Central Marine Fisheries Research Institute (CMFRI).
Published in the journal Current Science, the study links the unprecedented influx of juvenile sardines to monsoon rainfall and nutrient-rich upwelling, which spurred a bloom of microplankton, the primary food source for sardine larvae. The result was a spike in larval survival and a surge in sardine recruitment.
“The ecological trigger was beneficial initially, but later created intense competition for food among the juveniles, resulting in poorly nourished fish with lower weight gains,” said Dr U Ganga, principal scientist and lead author of the study.
“This led to a market crash in sardine prices and forced a halt in juvenile fishing to protect stocks.”
Oil sardines, once a cornerstone of Kerala’s marine economy, had plummeted from a record 400,000 tonnes in 2012 to just 3,500 tonnes in 2021. The 2024 influx, marked by young sardines averaging 10 cm in size, even caused mass beaching incidents in Kozhikode and Thrissur.
The study emphasised that ecosystem productivity, particularly microplankton-linked chlorophyll-a levels, had a greater influence on sardine recruitment than traditional spawning stock biomass measures.
With climate change driving more extreme marine conditions such as heatwaves researchers stress the urgent need for adaptive fisheries management.
“Dynamic, eco-region-specific harvest rules and short-term fishery forecasts are now critical to maintaining sustainability,” said Dr Ganga.
“These changes are essential to protect both marine ecosystems and the livelihoods that depend on them.”
