Fish in troubled waters

VENKATESH DUTTA

A river has a unique connection with gastronomy, culture, and diplomacy. Hilsa or ilish macch is not only a cherished delicacy but also a symbol of auspiciousness and fortune. When the river has an abundance of native fish like hilsa, the river is considered to be in good health.

Durga Puja often coincides with the end of the monsoon season, which is also when hilsa is most abundant. Hilsa spawns throughout the year, but the peak harvest season spans September and October. The fish is at its best quality during this period, making it a highly sought-after item for festive meals. Hilsa from the Padma river (the lower segment of the Ganga that flows in Bangladesh) is considered the best. The peak spawning season when fishing is traditionally banned happens to be an 11-day period around the full moon in the month of October which is the Bengali month of Aswin. The days are calculated as five days before, five days after and the day of the full moon itself.

This year, the Bangladesh government decided to temporarily suspend the export of hilsa to India a month before Durga Puja to ensure that there was an adequate supply for local consumers. The demand during this period was met from Myanmar which increased the price.

Earlier, in 2012, Bangladesh imposed a ban on hilsa export to India due to differences over the sharing of Teesta river water. The Ganga Water Treaty of 1996 and the ongoing Teesta River water-sharing negotiations are key aspects of India-Bangladesh relations, in terms of transboundary river management. The unresolved Teesta water-sharing agreement is still an intricate geopolitical challenge.

Bangladesh is the largest producer of hilsa, contributing around 75 percent of the global hilsa catch. About half a million fishers are directly dependent on hilsa catch. The country gets protein, employment and foreign currency — all from the export of this single species.  India contributes approximately 5 percent to the global hilsa catch, with West Bengal and Odisha being the main states. The Bay of Bengal provides the ideal estuarine and coastal habitats for hilsa due to its nutrient-rich waters and the confluence of major rivers like the Ganga, Brahmaputra and Meghna, supporting the highest hilsa populations.

In the late 1990s, the hilsa population started declining. WorldFish started a programme to conserve its habitat. The government of Bangladesh began a campaign called Hilsa Fisheries Management Action Plan. The focus was on SAFE-ACT (Sanctuaries, Alternative livelihoods, Fishing ban, Enforcement, Compensation and Training).

It attempted to initiate several conservation efforts such as regulating overfishing and protecting the juvenile fish and restoring the migratory routes and river channels. Fishing is banned for several months a year along the coastal sanctuary areas. To compensate the fishing communities during these months, rice is provided to replace the income opportunity lost. As a result of all these campaigns and actions, the declining hilsa fishery revived with significant improvement in fish catch. The average size of hilsa doubled, so also the income of fishers. These interventions also improved other fish biodiversity.

The hilsa is an astonishing migratory fish known for its long upstream journeys. The upriver migration of hilsa indicates connected river systems. Historically, hilsa have been known to migrate more than 1,000 km upstream in the Ganga-Brahmaputra-Meghna river system, reaching as far as Allahabad and even Varanasi in Uttar Pradesh. The extent of migration has reduced considerably in recent years, and hilsa rarely reach as far upstream as they once did. They spend most of their life in the sea but migrate to freshwater rivers to spawn. This is comparable to the migratory patterns of Atlantic salmon.

In the Bay of Bengal, adult hilsa mature in the coastal waters and migrate into the estuaries and upstream freshwater stretches of the Ganga river and its tributaries for spawning. Therefore, longitudinal connectivity of rivers is very important for the growth and survival of hilsa. The construction of barriers like the Farakka Barrage, which was completed in 1975, has severely restricted the natural migration routes of hilsa. The barrage was built to divert water from the Ganga to the Hooghly river to reduce siltation near Kolkata, but it also impeded the upstream movement of fish.

Today, the upstream migration of hilsa in the Ganga river system is mostly restricted to lower stretches. In Bangladesh, hilsa continue to migrate into rivers like the Padma, Meghna, and Jamuna, and spawning still occurs in freshwater zones.

Hilsa is a keystone species in the Ganga river ecosystem. Its decline has affected the entire food web, impacting predators such as dolphins and larger fish that rely on hilsa as a food source. Large-scale water extraction for agriculture and urban use has altered river flows, reducing water levels during the dry season when hilsa typically migrate upstream to spawn.

The decline in the migratory range and habitat of hilsa underscores the need for integrated transboundary river management to protect this iconic species and its critical habitats. One sign of a good gesture is that both Bangladesh and India have established hilsa sanctuaries in key riverine and estuarine zones to protect critical spawning habitats. These protected areas aim to reduce fishing pressure and allow hilsa populations to recover.

Engaging local fishing communities in conservation initiatives and providing alternative livelihoods during the fishing ban periods have been key strategies in reducing pressure on hilsa stocks.

Venkatesh Dutta is a Gomti River Waterkeeper and a professor of environmental sciences at Ambedkar University, Lucknow