A 22-day fishing ban during the ilish breeding season and a two-month ban on catching jatka (juvenile ilish) are designed to boost the fish's production and availability. Backed by scientific research, the initiatives have helped more than double ilish production in Bangladesh over the past two decades.
However, that upward trend has now reversed, with production declining for two consecutive fiscal years. The fall has raised questions about whether the fishing bans' benefits are being sustained, or whether weak enforcement and river-level environmental changes are undermining efforts to protect the country's national fish.
The recent decline has also prompted researchers and fisheries officials to question whether fishing bans and enforcement drives alone are enough to increase ilish production.
According to fisheries researchers, protecting mother ilish during spawning and allowing juvenile fish enough time to mature are essential for sustaining the population.
Studies show that ilish spawning activity increases around new and full moons, when mother ilish carry mature eggs. The 22-day fishing ban during the breeding season is designed to give them an uninterrupted opportunity to spawn. A separate two-month ban on jatka fishing aims to allow juvenile ilish to grow.
Questions over enforcement
Despite the restrictions, concerns remain over their effective implementation.
During the first 15 days of the 22-day ban, which began on October 8, visits to several riverside areas in Chandpur found that enforcement drives by task forces comprising river police, Coast Guard, district administration and fisheries officials were limited compared with the vast river network.
Unscrupulous fishers continue to take advantage of gaps in surveillance, while large numbers of fishing nets remain visible in the rivers. Limited funding and resources make round-the-clock patrols difficult. There have also been allegations in some areas that people involved in enforcement operations have assisted illegal fishing.
Chandpur District Fisheries Officer Md Kamrul Islam told Dhaka Tribune that authorities were trying to make the drives effective despite limited resources across an extensive river network.
He said fishers and fishing communities needed to become more aware of the restrictions and cooperate with the administration.
How are the fishing bans determined?
Fishing restrictions are scheduled based on ilish's breeding cycle, spawning periods and the growth cycle of juvenile fish. The restrictions generally fall into two categories.
Mother ilish conservation drive
The 22-day ban is imposed around the peak spawning period, usually covering the full moon in and around the Bengali month of Ashwin. This year, the restriction ran from October 8 to October 29.
Jatka conservation drive
A separate restriction is imposed to allow juvenile ilish, known as jatka and measuring less than 25 centimetres, to grow safely in coastal rivers and estuaries.
The jatka conservation period runs for eight months, from November to June, although fishing restrictions in designated areas are enforced according to the official schedule.
What researchers say
Dr Taiefa Ahmed, chief scientific officer at the River Centre of the Bangladesh Fisheries Research Institute, told Dhaka Tribune that the institute's scientists had been studying ilish for years.
Analyses of research data from different projects showed that September was once a crucial period for ilish spawning. However, climate change has shifted the breeding season, prompting authorities to move the mother ilish conservation drive to October.
She said the timing had been determined through scientific analysis of research data.
The institute had proposed a 22-day fishing ban covering one new moon and one full moon to protect mother ilish, she said, adding that the government had adopted the recommendation.
The objective is to increase ilish production by allowing mature fish to spawn undisturbed. Research has found that mother ilish carry large quantities of mature eggs during this period and are more likely to be caught in fishing nets. ilish availability also increases around new and full moons, making restrictions during this period particularly important.
Where are the benefits of the bans?
On the recent decline in ilish availability, Dr Ahmed said production had been much lower in Bangladesh before 2000.
Based on findings from the Fisheries Research Institute, the government introduced programmes to protect mother ilish during spawning and allow juvenile fish to mature through jatka conservation measures. These initiatives subsequently helped increase production.
However, river pollution and fishing during restricted periods are now having a negative impact, alongside the effects of climate change, she said.
Dr Anisur Rahman, a former principal scientific officer of the Bangladesh Fisheries Research Institute and a ilish researcher, told Dhaka Tribune that ilish spawn throughout the year, but the volume is higher around full moons.
As fishing cannot be suspended throughout the year, researchers initially selected a full moon in October for the conservation drive. Later studies found that ilish also release substantial quantities of eggs during new moons, although the amount is somewhat lower than during full moons.
He said mature eggs have a higher chance of producing surviving juvenile fish.
According to research, a continuous 22-day fishing ban should begin two days before whichever occurs first in early October — the new moon or the full moon. The restriction, centred on both lunar phases, was designed to protect ilish stocks while taking fishing patterns into account.
“Just as a crop cannot grow without sowing seeds, ilish cannot reproduce unless they are allowed to spawn. Without juvenile fish, there will be no ilish in the future,” he said.
However, he acknowledged that enforcement of the restrictions had faced problems in recent years.
He said several factors were responsible for the decline in ilish catches and that authorities needed to identify and address them.
Production on the decline
According to the Department of Fisheries, Bangladesh produced 255,839 tons of ilish in fiscal year 2003-04. Of the total, 71,001 tons came from inland waters and 184,837 tons from marine waters.
Over the following two decades, production increased by between 1% and 8% in different years.
In FY2022-23, total production reached 571,342 tons, including 271,330 tons from inland waters and 300,012 tons from marine waters.
However, the upward trend began to reverse in FY2023-24, when production fell 7.33% year-on-year to 529,487 tons.
Production declined further to around 500,000 tons in FY2024-25.
Factors behind the decline
Ilish researchers have identified river pollution, changes in river channels and submerged shoals, unplanned sand extraction using hundreds of dredgers, and fishing in violation of seasonal bans as major factors behind the decline.
They say announcing fishing bans alone will not be enough to sustain production.
Effective enforcement must be ensured alongside greater efforts to protect ilish's natural habitats, migration routes and breeding grounds.