The Hindu Business Line : Many fish species adapting to climate change: Study

Kochi May 3 Some of the commercially viable maritime fish species have begun to adapt to the climate changes and warming ocean temperatures of the Indian coastline.

In a study, Dr E.Vivekanandan, Head of the Demersal Fisheries Division of Central Marine Fisheries Research Institute (CMFRI) has observed that the highly popular oil sardines have moved up to new geographical zones as the seas there have begun to warm up.

With the Northern latitudes becoming warmer, oil sardines, an essentially a tropical species, have been observed to establish in new territories and contribute to the fisheries along the North-West and North-East coasts of India.

Other commercially important species have evolved equally interesting strategies for survival.

As the surface temperatures of Indian seas have begun to warm up, species like the Indian mackerel have gone down to different depths and are increasingly becoming the catch of bottom trawlers.

Species like the threadfin beam appear to have shifted the months of peak spawning towards the colder months, off the coast of Chennai.

As the seas have warmed, the season when copepods were found in large abundance off the coast of Mangalore, have now shifted to the colder months.

These findings indicate that the adaptable species may be able to adjust to the immediate challenges of rise in temperatures for a shorter or a longer duration.

However, the more vulnerable groups such as the corals are in deep peril.

It was observed that extensive coral bleaching had occurred in the Gulf of Mannar, the Andaman and Lakshadweep seas when the sea temperature was 31 degrees Celsius or more in 1998 and 2002. This intensity of bleaching was found directly related to the number of days when higher temperature prevailed.

While some answers have been found on the impact of sea warming on different fish species, several questions remain unanswered. What will be the influence of seawater temperature on the Bombay duck, whose northern boundary is landlocked?

What will be the distribution and migration patterns of oceanic tuna as the global seas warm up? The sex of sea turtles is critically determined by the soil temperature at which the embryo develops.

Prevailing temperatures above 28 degree Celsius produces only females.

Is the massive intrusion of puffer fish and medusae into the Indian coastal waters in recent years a fallout of climate change?

The effect of climate change on fisheries will affect the fisheries sector, which is already characterised by stagnating catches, utilisation of resources at peak levels and large overcapacity and conflicts among the stakeholders - traditional fishermen, mechanised boat operators and deep sea fishing vessels.

It is likely that existing craft and gear combinations will be modified to meet the new challenges.

This could very well ignite fresh conflicts among the stakeholders.

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