Vegetarian fish find the seaweed greener in south

Goa, it seems, has drawn the territorial line between domains of herbivorous and carnivorous fishes in the Arabian Sea.The preparation of an atlas on environmental parameters and productivity of the Indian Exclusive Economic Zone and adjoining areas has thrown up interesting factors such as the predominant habitats of carnivorous and herbivorous fishes.Studies reveal that carnivorous fish, such as Bombay duck and ribbonfish, mostly choose to stay in waters to the north of Goa.Herbivorous varieties, such as sardine and anchovy, prefer to stay in waters to the south of that State, says K.K.C. Nair, project leader.The studies shatter the belief that phytoplankton is produced mostly in parts of the seas which receive the most sunlight. It has been found out that the production takes place at a depth of 40 to 60 metres, he said.The productivity of phytoplankton in the Bay of Bengal is nearly half that recorded in the Arabian Sea. This is directly linked to fish productivity as it forms the first link in the food chain, he said.The scientists have identified environmental hotspots in the sea off Kochi, Kollam and Kozhikode.The relative abundance of toxic elements, such as nitrous oxide, has been recorded in the coastal belts of these areas, indicating pollution from agricultural waste and effluents from industrial units.The studies have identified some new promising fish breeding grounds off the Kerala waters. During the southwest monsoon, breeding grounds of sardine have been identified off Kannur.During the winter months, sardines breed off Kochi, 15 nautical miles on the seaward side at a depth of 20 metres, says Dr. Nair, who led the research team consisting of 14 scientists and 25 research fellows.The scientific relevance of the atlas is that it is the most exhaustive study on the nvironmental parameters and productivity of the Indian waters since the one done during 1960-65 under the auspices of UNESCO. The scientific research vessel Sagar Sampada was used for the 41 cruises that were conducted and various parameters pertaining to the environment and productivity were continuously monitored for eight years, Dr. Nair adds.

The Hindu, 24^th September 2008