Excessive fishing in the Bay of Bengal has threatened availability of a number of commercially important fish species in the area, analysts said.
Already, caches of various fish species like threadfin, barramundi, pomfret, black zone, eel fish, croaker and red snapper have fallen to very low levels due to bottom trawling, fisheries officials said.
"Once large quantities of these fishes were caught," said Nasiruddin Md Humayun, director (marine) of the Department of Fisheries (DoF).
The stock of 15-20 commercially important fish species has been falling gradually for the last three-four years, he said. "The stock will be exhausted unless bottom trawling stops," he said, adding that these fishes have demand in both domestic and export markets.
Currently, around 225 trawlers and 44,000 motorised and non-motorised boats are engaged in fishing in the Bay which has 65 commercially important fish species and 36 shrimp varieties, according to DoF data.
Of the trawlers, 118 trawl along the sea floor to catch whitefish. The number of such vessels is rising every year as a section of people get engaged in fishing by obtaining temporary permits from the High Court for 'trial fishing'.
Once these economically important fishes were easily available in the 50-metre depth of water, Humayun said.
As catches near the coast are falling, some trawlers have started fishing beyond the 50-metre depth area, he said.
Mohammed Shahjalal, former secretary general of Bangladesh Marine Fisheries Association, said catches of such fishes have been falling for the last five years.
"It might be a result of overexplo-itation," he said.
MA Kader, a former professor at the Institute of Marine Science and Fisheries at Chittagong University, said fish stock, including that of shrimp, in both mid and bottom waters of the sea has depleted.
"This is because of excessive fishing. The number of trawlers that are engaged in fishing is more than needed. There are rules but none cares," he said.
Md Rashed-Un-Nabi, a professor from the same institute, suggested an intensive survey to determine the stock of fishes in the Bay. "Then we can say what types of fishes are available and whether these can be exploited."
The last detailed survey of marine stock was conducted more than two decades ago.
DoF officials said the government is in the process of buying a research vessel to conduct a survey in the sea. The vessel is due by yearend or early next year.