Survey blames overfishing as pelagic species decline sharply

Fish stocks in the Bay of Bengal have declined sharply in recent years due to overfishing, raising serious concerns about the sustainability of marine resources, according to a fisheries resource and ecosystem survey released yesterday.

The survey found that the stock of small pelagic species has fallen to nearly one-fifth of previous levels -- down to 33,811 tonnes in 2025 from 158,100 tonnes in 2018.

This means pelagic fish, which live near the surface, have declined by 78.6 percent in seven years. The findings were shared at an event jointly organised by the FAO and the Ministry of Fisheries and Livestock at a hotel in the capital.

The survey was conducted with support from the Food and Agriculture Organization (FAO) and Norway.

The latest results follow a 2019 survey, which concluded that marine fisheries were heavily exploited, with several species severely depleted. Highly exploited groups include Tiger shrimp, Indian salmon, and large croakers.

Abdullah Al-Mamun, assistant director of the Department of Fisheries and co-cruise leader of the survey, told The Daily Star that overfishing is the main reason behind the current situation. In 1985, around 100 commercial trawlers operated in the Bay; that number has now risen to 273.

He said the decline in the number and size of commercially important fish is alarming, and urged the government to reduce the number of commercial trawlers to prevent further damage. Ecosystem disruption and environmental degradation have also contributed to the decline, he added.

The survey was conducted from August 21 to September 21 across Bangladesh's entire exclusive economic zone of 118,813 sq km.

It included oceanographic measurements, fisheries trawling, plankton and jellyfish studies, and microplastic sampling. The work is part of the EAF-Nansen Programme, carried out using the research vessel Dr Fridtjof Nansen with support from the FAO and Norway.

The 2019 Department of Fisheries report stated that the current management system allows excessive and increasing fishing pressure, and called for urgent steps to stop fleet growth and gradually reduce total fleet size.

Preliminary results from the new survey recorded 65 marine species for the first time in Bangladesh, including five possibly new to science.

According to the ministry data, the Bay of Bengal has 475 species of fish, 36 species of shrimp, five species of lobster, more than 15 species of crab, five species of turtles and 13 species of coral.

Abdullah Al Mamun said researchers have sent samples to a laboratory in South Africa for further analysis.

The survey also found that jellyfish, once more abundant in deep-sea areas, are now appearing in much larger numbers along the coast.

For the first time, the presence of Skipjack tuna and other tuna species has been scientifically confirmed within Bangladesh's exclusive economic zone.

Skipjack tuna were caught by trawls and hook-and-line, and scientists also observed tuna schools inside the exclusive economic zone. Skipjack tuna is a small, highly migratory species found in tropical and subtropical oceans worldwide, known for being the most abundant commercial tuna.Of the country's 20 major fish species, nine were commercially viable for harvest in 2018, but that number has now fallen to just five, according to the survey.

During the survey, 34 CTD stations were completed, and 275 water samples were collected for pH, alkalinity, and nutrient analysis. Plankton sampling at 32 stations identified 9,794 fish larvae -- including tuna larvae -- and 418 microplastics.

Fisheries and Livestock Adviser Farida Akhter said due to overfishing, illegal and unregulated fishing, and the use of harmful nets, the marine fish stock is declining, which is a matter of serious concern.

She said out of 273 industrial trawlers, 72 are using technology, but since it is not being used properly, bycatch and wastage are increasing.

In the Bay of Bengal, oxygen levels are low in some areas and high in others, there is a high concentration of microplastics, and an abnormal proliferation of jellyfish, she added.

These warning signs clearly indicate that Bangladesh's marine environment is facing serious risks, she mentioned.

She urged that the issuance of licenses for industrial trawlers be strictly limited and strict control be imposed on trawler-based fishing.

The adviser further said after receiving the final report in mid-December, the government will hold meetings with all relevant stakeholders and then take the necessary measures.