The Indian Spiny Turbot, a predator fish, once abundantly available in the sea off Kerala and favoured as a delicacy, could be heading for local extinction, according to researchers at the Department of Aquatic Biology and Fisheries, University of Kerala.
A study carried out by Biju Kumar and Pramod Kiran reported that increased fishing pressure and other human interventions in the oceans could have resulted in a sharp depletion of the predator, scientifically known as Psettodes erumei, one of the largest flatfish species in Indian waters.
The study based on data compiled by the researchers on the marine biodiversity of the Kerala coast observed that predator populations characterised by species such as sharks and turbots, were declining
It noted that the Indian Spiny Turbot, once commonly available, had not been reported from the commercial catches of Kerala for the last 10 years.
Locally known in Kerala as “Aayiram Palli” for the long and sharp teeth in its mouth and “Erumai nakku” in Tamil, for its buffalo-shaped tongue, the spiny turbot was a cherished dish of the west coast and was preferred for its high nutritive value as well as high meat content and lesser bones. These characters also make turbots a favoured choice in many restaurants in Europe and America.
Growing to a maximum of 60 cm in length, and inhabiting the sand and muddy bottoms of coastal waters up to a depth of 100 m, the Indian turbot is commercially the most valuable flatfish of India and is
distributed in the Indo-West Pacific from Red Sea and East Africa to Japan and Australia. The species occupies a higher position in the food chain than that of larger predatory fish communities such as
sharks, rays, tunas and billfishes.
“Intensified fishing by trawlers could be the possible reason for the local extinction of Indian turbot, even though the impact of climate change needs to be investigated. The larger size of Indian spiny
turbot also makes them more vulnerable to fishing than other species of flatfishes”, the paper says.
The flatfish landings in India have recorded an increase from around 8,000 tonnes in the 1960s to the current rate of about 17,800 tonnes, which is primarily due to sharp increase in the number of trawlers.
“Since the Indian turbot is a strict carnivore and a fish occupying a higher position in the food chain, any possible local extinction may create serious repercussions on the delicate food web of the Indian
coastal waters”, says Mr. Kumar. “A questionnaire survey with fishermen in all the major fishing
harbours of Kerala also supports this argument as they report extinction of this species from Kerala coast”, he adds.
The paper calls for detailed fish population studies along Indian coast and the adoption of a precautionary approach towards the sustainable management of predatory species like the Indian turbot and
sharks. The study further recommends conservation of vulnerable species through aquaculture.