Correlation between changes in sea surface temperature and fish catch along Tamil Nadu coast of India - an indication of impact of climate change on fisheries?

Increase in mean sea surface temperature (SST) over the years is the primary indicator of ocean warming; which is likely to impact fish growth, reproduction and migration in the ocean. As a prelude to understanding changes in biotic communities along the Tamil Nadu coast of India, the trend in SST along the Tamil Nadu coast was assessed over a period of 105 years (1906-2010). The annual catch data of two major pelagic resources, the Indian oilsardine and Indian mackerel, and the annual catch (1979-2010) by the trawlers operating from Madras Fisheries Harbour, Chennai, were correlated with SST. There was an increase in minimum and maximum SST in all the seasons off Nagapattinam and Kanyakumari while at Chennai, the minimum SST in south-west monsoon season and maximum SST in summer season has decreased. The catches of oilsardine and mackerel showed an increasing trend over the last 25 years. Seasonal analysis showed positive correlation of the catches with SST. The catch of oilsardine during the summer months in particular showed an increasing trend over the period. Among the 17 dominant resource groups assessed, the catch of whitebaits showed significant positive correlation with increasing SST (at 5% level). Ribbonfish, perches and crabs also showed high `r' values but the correlation was not statistically significant.