The hilsa fish (Tenualosa ilisha) fishery, important for festivals and livelihoods across the Ganga-Brahmaputra-Meghna delta, is under increasing pressure from warming seas, a stressed delta, and national borders.
Between 1956-1962, 94% of Bangladesh’s hilsa catch came from rivers, but today, about 72% is from marine waters. Riverine catches peaked in the 1960s, while marine catches rose sharply from the 1990s, partly due to barriers to upstream migration.
Hilsa are anadromous, migrating upstream to breed in freshwater. Ideal breeding temperatures are 29.3°C to 30.2°C, with salinity below 0.1 ppt. Warming seas in the Bay of Bengal disrupt breeding cues, while erratic monsoons weaken river surges, allowing seawater to creep inland and increase salinity.
Climate change effects are compounded by infrastructure development and pollution. Siltation can reduce river channel depth, and chemical waste further damages ecosystems. Overfishing, especially of juvenile hilsa (jatka), depletes stocks and reduces the population’s ability to replenish itself.
Fragmented marine management and uncoordinated fishing bans across countries like Bangladesh and India create regulatory loopholes, leading to overexploitation of hilsa stocks in the northern Bay of Bengal. Experts advocate for a coordinated Ecosystem Approach to Fisheries Management (EAFM) and synchronized fishing closures, joint stock assessments, and consistent enforcement of regulations across borders.
Source: Down To Earth