Sardines used to form the major catch for traditional fishermen who ventured out to sea during the trawl ban in Kerala’s coastal waters. But the availability of sardines has declined to alarming levels, affecting the livelihood of hundreds of fishermen. Climate change has threatened fish habitats. Fishing by foreign vessels beyond the trawl ban area and incursion by boats from neighbouring States have caused serious erosion in the fish wealth, says V. Dinakaran, general secretary, Akhila Kerala Dheevara Sabha. Drastic reduction in shoals There has been a drastic reduction in shoals of sardines in the sea, according to him. Most fishermen across the coastline share the opinion. The Central Marine Fisheries Research Institute (CMFRI) conducted a research study on the decline in fishery of Indian oil sardine off the Kerala coast during 2012-15. The report, released recently, attributes it to overfishing and climatic change. The decline has hit over 70,000 fishermen who directly depend on the resource for livelihood, the study says. Sardines have been caught from coastal waters mainly using seines for about 200 years. The catch per unit effort (CPUE) of mechanised ring seine (MRS) units increased from an average of 1.2 tonnes in 2007 to 3.2 tonnes in 2012. Sardines have been fished within the 30-metre-deep zone along the coastline for many decades. During 2012-13, fishermen fished in areas up to 55 metres, mainly during March-May, the period when sardines mature and become ripe for spawning. CMFRI estimate As per an estimate of the CMFRI, based on 2005-2007 data, the maximum sustainable yield (MSY) of sardine along Kerala coast is 2.3 lakh tonnes. But during 2011 and 2012, the stock was fished above the MSY by harvesting nearly 2.5 lakh tonnes. About 16,040 tonnes of juveniles (less than 10 cm) were harvested in 2012 and about 4,802 tonnes in 2013. It could have affected the spawning biomass of 2013, 2014 and 2015. (16,040 tonnes of sardine of less than 10 cm in size would have contributed to a biomass of 5,61,400 tonnes at 30 per cent mortality in the subsequent years). Sardines in the 10-14 cm size group, less than one year old, form a major component of sardine population. During the period from October 2012 to February 2013, about 1,17,823 tonnes of this category was harvested, adversely affecting the spawning biomass in the following years, according to the report. Changes in ecosystems have affected the spawning of various kinds of fish, says T.D. Jojo, a researcher working for the Ashoka Trust for Research in Ecology and Environment (ATREE), a non-government body which conducts annual survey on fish species in Vembanad. A recent study conducted by the organisation also indicated a decline in the number of fish species existing in the ecosystem.
2016, The Hindu