Stocks of at least six fish species in the Sundarbans are falling because of illegal fishing, the killing of fry and environmental stress. By contrast, stocks of nine species are rising under the influence of environmental changes, including greater freshwater flow. Stocks of the remaining species are at tolerable or stable levels. The findings come from a study titled “Assessment of Aquatic Resources of the Sundarbans”, conducted over nearly two years.
The study found rising stocks of olua or amadi, parshe (goldspot mullet), bhetki or koral (barramundi), poa, datina, gagra tengra, pangas, horina prawn and chaka prawn. Stocks of payra or chitra or bishtara, nona tengra, kain magur, golda prawn (giant freshwater prawn), bagda prawn (tiger prawn) and shila crab (mud crab) are falling. The researchers identified illegal fishing, the catching of small fry and environmental pressure as key causes of the changes.
The survey was carried out by eight researchers led by Dr. M. Enamul Hoq, a former director of the Bangladesh Fisheries Research Institute. Arannayk Foundation and the Centre for Natural Resource Studies (CNRS) implemented it under the Forest Department’s Protection of Sundarbans Mangrove Forest Project.
“Our main task was to determine the current state of the fish, the size of the stocks, the threats and future management,” said Hoq, who led the research team. “We found that while larger species such as bhetki used to be more abundant in the Sundarbans, smaller species have now become somewhat more abundant.”
He said the stock status of about 15 fish and prawn species was analysed, and at least six of them are in decline. New restrictions on net mesh sizes and on fishing could be imposed to protect the species whose stocks are falling.
The study points to overfishing of bhetki in the Satkhira range, pressure on pangas stocks in the Khulna and Sharankhola areas, and overfishing of gagra tengra in Sharankhola. Experts recommended catch quotas, bans during the breeding season and the protection of fry to control the catch of these species. They also stressed the need for strict controls on the harvesting of mud crab and of golda and bagda prawns.
Poison fishing a major threat
Experts say one of the biggest threats to the aquatic resources of the Sundarbans is fishing by putting poison in canals. The method kills not only the targeted species but also other fish, fry and small aquatic animals. The practice of keeping the desired species when collecting fry and throwing away other aquatic animals is also harming biodiversity.
Dr. Mohammad Zakir Hossain, a former regional director of the International Union for Conservation of Nature (IUCN) and team leader of the ongoing Ecological Monitoring of Sundarbans project, said fish are a vital resource for the livelihoods of people who depend on the Sundarbans. Illegal fishing, poisoning and the catching of small fry must stop, he said, and steps must be taken to ensure conditions favourable to breeding and to increase fish production.
Seven new species found
The study found seven species of fish and prawn not previously recorded in the Sundarbans: five fish and two prawns. The newly identified fish include ek thuita, kuli bele, sabuj bail or fonta bele, fonta bat and bara aish parshe. The two new prawns are the spider prawn and the spotted prawn.
Hoq said about 261 fish species were found during the two-year survey. Combined with data from earlier studies, about 382 fish species are now known to exist in the Sundarbans. For the first time, seven species were formally identified using DNA barcoding.
Hoq said that although the overall condition of fish in the Sundarbans is satisfactory, there is pressure from human activity, climate change and people who depend on the forest for their livelihoods. In his view, the biggest concern at present is fishing with poison.
বাংলায় মূল প্রতিবেদন পড়ুন · Read the original Bengali report