Hilsa production declines due to harsh nature, human greed

The hilsa fishing season is ongoing, but Siddique Majhi, 53, a fisherman from Mahipur River Port in Patuakhali, is disappointed. Despite going to the sea seven times this year, he did not catch fish as expected. During his latest 10-day fishing trip, he spent nearly Tk 600,000. He earned only a small profit from selling the fish. He stated that the costs from the previous six trips were not recovered.

Previously, big-sized hilsa could be caught near the mouth of the Bay of Bengal from Mahipur during the peak season. Nowadays, fishermen have to go deep sea in search of big fish, which increases expenses, including fuel and other costs. Siddique Majhi said, “I have never seen such a low catch before. For the past seven to eight years, fish availability has not been good. To get big fish, we have to go far away.” Recalling the situation 20–25 years ago, he said, “Back then, we used to bring a boatload of hilsa. Those hilsa used to sell for Tk 1 million to Tk 1.2 at that time. Both the owners and we were happy.”

For many fishermen like Siddique Majhi, everything now seems unfamiliar. Conversations with fishermen from Mahipur, Alipur, Bhola, and Cox’s Bazar reveal that there are multiple reasons behind the decline in hilsa production.

During the breeding season, hilsa fishing is banned, and various initiatives such as alternative employment or support for fishermen had increased hilsa production in the country for a few years. However, many doubted or still doubt how much the government’s statistics reflect reality. According to the Department of Fisheries’ own figures, hilsa production decreased by at least 7 per cent in the last season, 2023–24, compared to the previous year.

About 12 per cent of the country’s total fish production comes from hilsa species. Its role in coastal livelihoods, rural market vitality, and even foreign currency earnings is immense. However, in recent years, hilsa production has been declining due to multiple natural and human-induced reasons.

Among natural causes, the first is climate change. The temperature of the Bay of Bengal is gradually rising, which is unfavourable for hilsa breeding and growth. Reduced river flow in the upstream, especially during the dry season, disrupts hilsa’s natural migration. The increase in sandbanks at the Meghna estuary narrows hilsa’s main migration paths. Besides, pollution in rivers and coastal areas, especially from industrial waste and plastic, threatens hilsa’s habitats and food chains. Experts also believe that overfishing without regulation contributes to the decline in hilsa production.

Although Bengalis have had a long association with hilsa, much remains unknown about the fish. Professor Md Shamsul Alam of Bangladesh Agricultural University, the first person to uncover the genetic mystery of hilsa, told Prothom Alo that hilsa is a very sensitive fish. It is born in the sea but must migrate to freshwater to lay eggs. Then the hilsa fry returns to the sea. For hilsa to grow and develop, water must be clean and pollution-free. Without a good environment, hilsa avoids certain areas and takes different routes.

For a decade, hilsa catches had been increasing continuously. According to the Department of Fisheries, in 2023–24, hilsa catches decreased by 42,000 tonnes. In 2022–23, hilsa catches were 571,000 tonnes, while it was 529,000 tonnes in the last fiscal year. Is hilsa truly taking different routes now?

The 432-kilometer area from Satnal in Chandpur district to Char Alexander in Lakshmipur (100 km), Madanpur to Char Piyal in Bhola (90 km), Bheduria in Bhola to Char Rustam in Patuakhali (100 km), Andharmanik in Patuakhali (40 km), lower Padma in Shariatpur (20 km), and Hijla in Barishal (82 km) has been marked as hilsa sanctuaries. But is hilsa safe even in these sanctuaries?

Abdul Bari Jamadar, president of the Chandpur Fish Traders’ Association and engaged in fish trade for several generations, believes that hilsa is no longer safe even in its usual habitats. He says hilsa production has been declining continuously for nearly four years, and this year’s production is at least half of last year’s.

Large concentrations of hilsa are now found in the Meghna River and its coastal areas. However, many researchers say that major obstacles in these areas are blocking hilsa’s migratory routes.

Bari Jamadar added that navigability is almost non-existent in some parts of the river. Boats get stuck. Where will the fish come from?

Hilsa is naturally a migratory fish, constantly moving from the sea to rivers and back. But its migration routes are now being obstructed.

Recently, the Department of Fisheries identified 17 locations in the Meghna, Tentulia, and Padma rivers where the movement of mother hilsa and fry is impeded. Of these, 14 are in the Meghna River, two in the Padma River, and one in the Tentulia River. These areas span Bhola, Barishal, Patuakhali, Chandpur, Lakshmipur, Noakhali, and Shariatpur districts.

Recent surveys on hilsa migration routes show that in the estuaries of the Meghna and Tentulia rivers, as well as parts of Chandpur, Bhola, Patuakhali, and Lakshmipur, numerous sandbanks obstruct the natural movement of hilsa. Local fishermen said that fish no longer migrate upstream as before. Although some hilsa appear during the strong currents of the monsoon, rivers remain largely empty during the dry season.

The same problem is observed in Daulatkhan in Bhola, Doshonachar in Patuakhali, and Haimchar in Chandpur: “Less water, more sandbanks, and fewer fish.”

Fisheries researcher and chief scientific officer of Bangladesh Fisheries Research Institute, Mymensingh, Mohammad Ashraful Alam, says, “Reduced river navigability is one of the main reasons. In the estuaries of the Meghna and Tentulia rivers, the number of sandbanks has increased alarmingly in the past decade. Even if partially submerged during high tide, these sandbanks block fish movement during ebb tide. During the breeding season of mother hilsa, upstream migration is hindered, and many fish get trapped in nets while crossing sandbanks even during high tide.”

According to fishermen said that these sandbanks not only block hilsa but also disrupt boat navigation. During storms or bad weather, fast trawlers collide with sandbanks or submerged bars, causing accidents and damaging engines and boats.

Abdur Rahman, a fisherman from Lakshmipur, said that often while fishing, they have to navigate around sandbanks, which increases both time and cost.

River depth and water clarity are crucial for hilsa’s life cycle. The increase of sandbanks and river islands reduces depth, while pollution affects water clarity. Reduced upstream water flow is a major crisis for Bangladesh’s rivers. Various embankments and water withdrawals in India and Nepal have significantly reduced the flow of the Padma, Jamuna, and Meghna rivers, especially during the dry season. Reduced flow increases salinity intrusion, disrupting hilsa’s natural migration cycle.

A study published in the American Journal of Climate Change, titled “Climate Change and Anthropogenic Interferences for the Morphological Changes of the Padma River in Bangladesh,” mentions that changes in rainfall patterns alter flood behaviour, affecting the Padma River’s geomorphology. Abnormal rainfall also changes the river’s sediment content, which may take a long time for the river to adjust to its flow and geomorphic characteristics.

Hilsa was once mainly associated with the Padma River. But those days are gone. The river is now much more degraded. Reduced river flow has significantly lowered hilsa production, according to the journal Asian Fisheries Science.

Hilsa researcher Anisur Rahman said that if water flow near the Hardinge Bridge on the Padma decreases by 38–40 per cent, hilsa availability or production drops by at least 26 per cent. This has already caused a major impact in the Padma and Meghna regions. Further reduction in water flow will inevitably worsen the situation for hilsa.

Whenever freshwater flow in rivers decreases, salinity rises in sea-adjacent rivers. Surveys at the Meghna estuary show that salinity raises to 10 ppt during the dry season, which is nearly double compared to 10 years ago.

A joint study by the Bangladesh Meteorological Department and the Norwegian Meteorological Institute has found that rainfall has decreased almost everywhere in the country, while temperatures have risen.

According to the study, between 1901 and 2022, Bangladesh’s annual average temperature rose by nearly 2°C. By 2050, the average sea surface temperature in the region could rise by about 1.2 to 1.5°C compared to current levels. The ideal temperature for the breeding and growth of hilsa is 26–28°C. If the temperature rises, hatching rates decline, juvenile mortality increases, and the quality of plankton—hilsa’s main food source—also changes.

Senior meteorologist Md Bazlur Rashid said, “With this global trend of rising temperatures, Bangladesh’s fisheries, particularly the hilsa sector, could be seriously affected. In fact, they already are.”

He noted that temperature rise is making survival difficult not only for humans but also for cold-water species like hilsa. Rising water temperatures are forcing hilsa to shift their breeding and migration grounds, disrupting their natural life cycle.

The study also stated that monsoon winds generally enter Bangladesh through the Cox’s Bazar coast between late May and the first week of June, retreating by September. But since 2000, the monsoon has sometimes been delayed until the second week of June. Last year, it began on 8 June. Similarly, withdrawal has also been delayed—sometimes lasting until 23 October in recent years.

Renowned hilsa researcher Anisur Rahman told Prothom Alo, “Reduced rainfall during the monsoon, along with higher temperatures, is undoubtedly affecting hilsa breeding. This is not good news for us.”

Temperature analysis in Bangladesh shows an overall warming trend, with the greatest rise in maximum and minimum temperatures recorded at the Chandpur station near the Padma River. Meanwhile, rainfall trends differ. Annual rainfall has increased most (+10 mm per year) in the hilly districts of southeastern Bangladesh, while stations in Rajshahi, Bogura, Ishwardi, Dhaka, Faridpur, Cumilla, Satkhira, and Barishal show declining trends (−0.30 to −7.93 mm per year).

Industrial waste, excessive pesticide use in agriculture, and plastic pollution are reducing dissolved oxygen (DO) in rivers, harming fish respiration and feeding. In hilsa sanctuaries like Chandpur’s Shatnol to Lakshmipur’s Char Alexander, mass fish deaths have occurred at least once a year for the past three years. It happened twice in last dry season.

Water quality in hilsa habitats of the Padma and Meghna rivers is deteriorating, while available food is shrinking. Experts warn this will eventually hurt production. Already, hilsa output has declined, with pollution cited as a major cause.

At the government’s River Research Centre in Chandpur, scientists monitor water quality year-round, testing for dissolved oxygen, pH, water and air temperature, hardness, and ammonia. DO is considered a key indicator: levels below 5 mg/L make water unsuitable for aquatic life. In the Padma, average DO dropped from 8.70 in 2018 to 5.41 in 2022.

Scientists have also detected microplastics in hilsa. A study published in UK’s renowned paper titled ‘Water, Air, and Soil Pollution’ in April found microplastic particles in all 20 sampled hilsa—around 10 particles each. Researchers from Dhaka University and Shahjalal University of Science and Technology (SUST) also found heavy metals like lead, cadmium, mercury, arsenic, and chromium in the fish.

Alongside natural challenges, human activities are equally responsible for declining hilsa stocks. Both researchers and fishermen admit that uncontrolled use of modern nets, especially ‘current nets’ and large encircling nets, are devastating river biodiversity. These fine-mesh nets catch everything from juvenile hilsa (jatka) to small fish, destroying potential breeding stocks before they mature.

Fisherman Nepal Halder from Mohipur, Patuakhali, said, “Now there’s a reign of nets under water. Wherever you go, there’s a net.” Nets are now longer—2,000 to 3,000 meters—compared to 1,000 meters in the past, trapping vast amounts of fish and blocking river passages.

The widespread presence of abandoned nets in seas and rivers has created another problem—ghost fishing. Sometimes nets remain in the water after being lost from sunken boats or discarded. Fish and aquatic animals get trapped in them, leading to unintended catch.

Patuakhali’s District Fisheries Officer Md Kamrul Islam told Prothom Alo, “The impact of ghost fishing is severe. It has become a major problem in our coastal areas.”

Professor Sazedul Haque of Patuakhali Science and Technology University has led a project for three years to remove these nets and curb marine pollution. Around 13,000 kg of abandoned nets have been recovered. Such nets, along with other harmful pollutants, were found not only along the Meghna coast but also everywhere including Cox’s Bazar and Lakshmipur.

At Mohipur and Alipur fishing ports, the number of large fishing boats has risen to around 200—compared to only 20 two decades ago. Local fisherman Nurul Majhi, who has fished for 45 years, said uncontrolled harvesting is putting hilsa at risk.

Currently, there are at least 30,000 small boats and 8,000 large vessels along Bangladesh’s coasts. Except during seasonal bans, there is virtually no restriction on hilsa fishing. Researchers estimate annual hilsa catch at around 600,000 metric tons—10–15 per cent higher than sustainable levels. Researcher Anisur Rahman believes this must be controlled.

Experts argue that a coordinated and sustainable model is needed to save hilsa. This should be based on scientific research into their breeding and life cycle, identifying new spawning and feeding grounds, and declaring them sanctuaries. Technology can play a key role: GPS tracking could monitor hilsa migration and fishing boats, while drones could help prevent illegal fishing in sanctuaries.