A quintessential Bengali delicacy and the national fish of Bangladesh ‘Hilsa' is passing through its toughest phase in a fight for survival, warn environmentalists and scientists.

“The fish is exploited by intensive fishery, indiscriminate exploitation of juveniles (jatka) and a disruption of migration routes. The loss of spawning, feeding and nursing grounds and increased river pollution are some of the causes known to have contributed to the steep decline of the fish,” said Dr. M. Niamul Naser, Department of Zoology, University of Dhaka.

In a research paper presented at ‘Ecosystem for life' -- a conference organised by the International Union for Conservation of Nature in Bangladesh recently -- Dr. Naser who co-authored the study with Professor Dewan Ali Absan said, “The over catching of jatka, lack of water supply, increasing number of fisherman and increasing siltation are among the major reasons for the fast decline in the hilsa numbers.”

Hilsa has a wide range of distribution and is found in marine, estuarine and riverine environments. The fish is found in the Persian Gulf, Red Sea, Arabian Sea, Bay of Bengal, Vietnam Sea, and China Sea. The riverine habitat covers the Satil Arab, the Tigris and Euphrates of Iran and Iraq, the Indus of Pakistan, the rivers of Eastern and Western India, the Irrawaddy of Myanmar, and the Padma, Jamuna, Meghna, Karnafully and other coastal rivers of Bangladesh.

“Hilsa fishery makes up for a large share of Bangladesh's total fish production and in terms of exports, the fish plays a significant role in the economy of Bangladesh. It is estimated that about two million fishermen and traders are engaged in hilsa fishing in the country,” said Dr. Naser.

Experts claim that scientific interest in the fish and its exploitation became evident in the late 1940s when attempts were made to define the major biological parameters of the species. Little attention, however, was paid to the fisheries.

“We know that till about 1972 hilsa fishery was restricted to the upstream rivers, mainly Padma, Meghna, Karatoya, Rupsa, Shibsa and Payra. However, now fishery has severely declined in the upstream areas and is mainly concentrated in the downstream rivers, estuaries, coastal areas and the sea. Also, the construction of the Farakka barrage in India has hit the fish hard. The fish is caught in the coastal and estuarine waters before they can migrate upstream for spawning. Local fishermen catch migrating adults from May to October, and the juveniles from February to May. Though Bangladesh has imposed a ban on fishing of this fish from March to April, it is hard to maintain this when they see fishermen in India catching these fishes just a few meters away,” said Dr. Naser.

“In our study, ‘Migratory, spawning pattern and anthropogenic interferences on hilsha fishery: Bangladesh-India initiative', we found that the conflicts in hilsa fishing included the fact that the number of fishermen has registered a sharp increase (in some places three times) in the past one decade. Many part-time fishers are harvesting hilsa in peak season, landless people (due to river erosion) become fishermen as they have limited alternate job opportunities and exploitation of the fishing community by money lenders, where fishers often have to lend money to buy nets, boats and others and then pay most of their catch to money lenders is pushing them to over catch the fish,” adds Professor Absan.

Stating that during the 1980s hilsa production was fairly stable; he notes that this trend has changed in the recent years. “Our research has shown that the production of the hilsa has indicated a sharp decline and what is worrying is the fact that there seems to be no halt to this descend,” adds Professor Absan.

The study concludes by recommending that there should be a hilsa management plan common to both the countries. “We need a wider trans-boundary population and genetic study to be conducted to see whether the two hilsa populations are same and possess any difference in their biology, especially their abundance, maturity and spawning habit. This information can be used to ensure that this popular fish is saved of its premature death,” added Dr. Naser.

Stressing the need for maintenance of ecological flow to ensure spawning and migration of hilsa, the study further states that there is an urgent requirement to identify new spawning grounds for the fish and bring in investigation on stakeholders' perceptions for the formulation of better conservation strategies.