Scientists have raised alarm over the exploitation of hilsa, Tenualosa ilisha, undoubtedly the most sought after fish in West Bengal and suggested a cap on its maximum sustainable yield per year.A paper titled Present Status of the Sustainable Fishing Limits for Hilsa Shad in the northern Bay of Bengal, India, published earlier this year by scientists from the School of Oceanographic Studies (SOS), Jadavpur University, points out that the value of recorded fishing mortality has exceeded the sustainable fishing mortality over the past few years, putting the species in danger.“To conserve the hilsa population in its natural habitat, the hilsa fishery needs suitable fishing regulations, restricting the number of fishing boats within 3,987 and maximum allowable hilsa catch (Maximum Sustainable Yield) at 25,440 tonnes per year in the northern Bay of Bengal region,” the publication states.This is the first attempt to measure the maximum sustainable yield of the hilsa species, particularly in West Bengal and offshore, Sugata Hazra, director, SOS, who is the principal investigator of the research and one of the authors of the publication said. The paper published in the National Academy of Sciences has also been authored by Isha Das, Sourav Das, Sandip Giri and Sourav Maity.Penal provisionWest Bengal Fishing Minister Chandranath Sinha admitted that the over-exploitation of the species is something which concerns the State government. “We are considering a proposal of having penal provisions for those who catch hilsa less than 500 grams of weight. Even those who buy the fish will be penalised,” Mr Sinha told The Hindu.Based on the advice of experts, the State government had issued notification of declaring five areas of the river Ganga, including a five sq.km. area around sand bars located in the rivers Matla, Roymongal and Thakuran in Sunderbans, where the river meets the sea as a hilsa sanctuary. As per regulations, all fish catching activities in these hilsa sanctuaries are prohibited from June to August and October to December.But according to experts these restrictions are far from being implemented at the ground level. The paper documents hilsa yield across three major fish landing centres — Digha, Diamond Harbour and Fraserganj in West Bengal — from 2002 to 2015 whic dropped to 13, 405 tonnes from 32,100 tonnes. In 2010, the hilsa yield was abnormally high in the State at 60,460 tonnes, which scientist say was an exception and could have have been triggered by global climate events.According to Professor Hazra, the publication points out that the hilsa fishery in the northern Bay of Bengal is “being unsustainably exploited” and the over fishing about 38% over the past few years (2012-16) has been noticed after comparing the fishing mortality.The publication points out that the annual catch has decreased by 13 % over the past decade and that the hilsa fishery in the northern Bay of Bengal is targeting smaller fish, which is unsustainable in the long run. Hilsa or ilish, as it is called in West Bengal is intrinsically linked to the culture of the State and makes 11% of the total fish catch of the State.Professor Hazra said that if the catch is regulated for a period about five years, the population will stabilise.