The Hindu : Kerala News : Fishes shift spawning season

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Saturday, Sep 29, 2007
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Kerala

Fishes shift spawning season

K.S. Sudhi

Survival tactics to overcome impacts of climate change

innovators: A file photo of threadfin bream, called Kilimeen, at the fish-landing centre on the Vypeen island. The fish seems to be adapting itself to global warming.

KOCHI: Call it survival tactics in the time of climate change. Two species of threadfin bream (Kilimeen), popular fish varieties in the country, have shifted their spawning season to cooler months in what is believed to be a tactic to overcome the impacts of global warming and resultant rise in seawater temperature.

Studies conducted at the Central Marine Fisheries Research Institute (CMFRI) here recently found that the spawning season of the two dominant species has changed off Chennai. According to the studies, 95 per cent of the spawning of the fish was found to have shifted to cooler months of October to March against the earlier 62 per cent.

In 1980, nearly 38 per cent of the annual spawning was recorded in warmer months from April to September when the sea surface temperature (SST) was between 29 degrees Celsius and 29.5 degree Celsius. Twenty-four years later, in 2004, the scientists found that it was reduced to just 5 per cent in the warmer months and 95 per cent during the cooler months at average sea surface temperatures between 27.5 degrees Celsius and 28 degrees Celsius.

The study was conducted by E. Vivekanandan, Head of Demersal Fisheries Division of the Institute, as part of the Indian Council for Agriculture Research-sponsored project on “Impact, adaptation and vulnerability of Indian fisheries to climate change.”

The fish has temporarily overcome the challenges posed by global warming and the resultant increase in sea surface temperatures by changing the spawning season. The catch has remained largely unchanged despite the shift in spawning season, Dr. Vivekanandan says.

Many more fish species may be adopting such survival and adaptation tactics in the face of global warning and increasing sea surface temperatures, which need to be explored. The survival strategies of Kilimeen were focussed on as the institute had well-compiled data of the spawning season and related behaviours of the fish for the past 25 years, he says.

The shift in the spawning season of the fish indicates changes in the physiological functions, which will have wider ramifications, such as the season of release of young ones and recruitment to the fishery. The fish is available throughout the year along the entire Indian coast.

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