This year, Islam was forced to leave his small fishing community in northern Mymensingh district to find work, an early victim of what scientists are warning is an alarming decline in freshwater fish stocks.

“Eight, ten years ago it was possible for a fisherman to make a decent living all year round – now, our catches are tiny and most people are having to find other seasonal work to survive,” Islam told AFP.

Surveys of fish stocks paint a gloomy picture.

According to a report by the International Union for Conservation of Nature (IUCN) in 2000, Bangladesh is home to 266 species of freshwater fish, 54 of which are classified as “threatened” in the group's Red List.

But a more recent study by the Bangladesh Agricultural University (BAU) stated that at least 25 of the freshwater species of fish are now extinct and over 100 species should be classed as threatened.

“We are losing our freshwater fish at an alarming rate,” said Professor Mostafa Ali Reza Hossain of the BAU, whose team has spent a decade travelling the country to track the decline in fish species.

The dwindling of freshwater fish has major repercussions for low-lying and deeply impoverished Bangladesh, home to numerous rivers, floodplains, lakes and lowland areas.

It puts over a million jobs at risk, will accelerate migration of the estimated 1.4 million fishermen to Bangladesh's already overcrowded cities, and removes a crucial, free source of protein for the rural poor.

It also risks having a catastrophic effect on overall biodiversity as the impact ripples up the food chain to birds and reptiles, Hossein said.

Inland fishing is deeply traditional in Bangladesh – as one old adage goes, fish and rice make a Bangladeshi – and another 11 million people are involved in seasonal or part-time fishing or fish-dependent businesses.

Many of these part-time fishermen come from the bottom third of Bangladesh's population -- the “ultra-poor” who cannot afford to buy more costly farmed fish, said Dhaka-based food and nutrition professor Keramat Ali.

“The very poor have traditionally relied on fish caught in inland rivers and lakes to supplement their diet – especially for pregnant women, children or the old and sick,” he said.

“These fish are crucial for protein supplies – without these fish in their diets, the poor will be missing out on key nutrients as well as protein. How are they meant to afford an alternative to these fish?” In Bangladesh, a nation with over two hundred rivers, fish accounts for at least 60 percent of the average person's total animal protein intake, according to the department of fisheries.

Overfishing, especially using illegal drag nets, industrial pollution of fish breeding grounds and the impact of pesticide run-off from farms are the primary reasons behind the decline, the BAU's research has found.

In addition, waterways are being filled up for construction of roads, bridges and houses to accommodate Bangladesh's ever-increasing population, which grew nearly two-and-a-half times in four decades.

“The 375-square-kilometre Chalan Beel, the largest inland wetland in the north, is a perfect example of how pesticide use and construction are having an impact on fish,” the BAU's Reza said.

According to BAU research, pesticide use has increased nearly sixfold since 1982, with fish production in Chalan Beel halving in the same period.

In addition, a 25-kilometre highway built nearly a decade ago dividing the Chalan Beel has severely limited fish movement which has had a devastating effect on fish breeding patterns, Reza said.

Commercial overfishing, including the use of gill and drag nets and explosives such as TNT are also a major part of the problem, Reza said. While such harmful fishing methods are illegal, the laws are rarely enforced.

“The adage 'fish and rice make a Bangladeshi' is already not true -- but if we don't act now to save our fisheries, the next generation face a tremendous loss for which they will, rightly, hold us responsible,” he said. – AFP