Fishing bans fail to arrest decline in hilsha population

The breeding season ban of 22 days on catching of hilsha has become effective from October 4 last. This yearly legal restriction was introduced in 2008 for 11 days covering a pre- and post-full-moon period. But a study found that hilsha is used to spawning during the new moon or dark moon too. This prompted the authority to lengthen the ban to 22 days around this time every year. During the early years, the ban produced positive results with the post-ban hilsha catch going up. Until 2019, a continuous uptick in hilsha harvest was reported. But over the past six years, the catch has continued to decline. During July-August, the peak hilsha harvesting period, this year, the catch amounted to 29,519 metric tonnes --a drop by 10,771 tonnes.   

Notably, hilsha spawns round the year and yet its main spawning season is October-November with the secondary spawning occurring in February-March and June-July periods. If there is a lean year after a few years of proliferation, there is nothing to be complained about. But this appears to be not an isolated off-season any more. Something has really gone awry. Or, why should the seasonal ban would not help proliferation of the hilsha population? In the fiscal year 2023-24, the production of hilsha came down to 529,000 tonnes from 571,000 tonnes in the fiscal year 2022-23. The production is likely to decline further in the current fiscal year. 

The argument that brood or juvenile hilsha (jatka) catching is responsible for the decreased production does not hold because the ban is enforced quite strictly. Ichthyologists indicate that the estuaries of rivers may provide an answer to the problem. Hilsha needs at least a depth of 30 feet water for their movement but now most of the estuaries have become as shallow as 8-9 feet depth of water during the low ebb. Also the pollution of river water is heavier than before. Hilsha is a sensitive fish and it avoids polluted water as much as it can. Or, even if mother hilshas lay their eggs, they do not produce broods in adequate number either due to pollution or even the climate change. 

Hilshas are unlikely to opt for other spawning zones located in Myanmar's or India's territorial waters. If that had happened, fishermen in those countries would have reported heavier catches of the fish. The other option for hilshas could be the Persian Gulf. This can as well be ruled out because the estuaries of rivers connected to the Bay of Bengal with all their flaws are better suited for a habitat of hilshas. 

Whether it is shallower water depth at the estuaries or pollution of water or a combination of both limits the proliferation of hilshas should be looked into. If the global warming is behind the increased siltation of the estuaries, this phenomenon should also be studied closely in order to find a solution to the degradation of the breeding zones. This poses a huge challenge to any country. All the neighbouring countries relishing a dish of hilsha or earning foreign exchange from its export will be required to develop a trans-boundary strategy to preserve the breeding zones of this fish. Industries and factories within the neighbourhood must be directed to follow safe disposal of effluent or wastes. 

However, if the global warming is responsible for decline in hilsha population, there is little hope of salvaging the situation. The planet is definitely getting more and more hostile to all living organisms. Unless the nations stop using fossil fuels, the climate change will inevitably worsen the crises. All living species will find it harder to stay put. But at least the disposal of plastic and polythene can be made safe and secure. If rivers are spared such pollution, the sea that meets the countries of South Asia will have a better health. Such initiatives can ultimately help save fishes including hilsha from extinction.

nilratanhalder2000@yahoo.com