Jellyfish Invasion: How Climate Change Is Decimating Fisheries—Are Your Favorite Seafood Dishes at Risk?

As climate change reshapes marine ecosystems, the Bay of Bengal is witnessing a dramatic shift that is leaving fishermen in Bangladesh struggling to adapt. Industry insiders report that since late January 2026, following a prolonged dry spell with minimal rainfall from November to January, the fishing landscape has transformed. Instead of traditional catches, nets are increasingly filled with dense masses of jellyfish.

This surge in jellyfish populations is not merely a nuisance; it indicates a broader ecological crisis driven by rising sea temperatures and acidification. Tanvir Shahriar Rimon, CEO of Rancon Sea Fishing, explained, "The higher the temperature and acidity, the more favourable it becomes for jellyfish. Once jellyfish dominate an area, fish cannot sustain there. They move elsewhere." This shift has been particularly pronounced in deep-sea zones beyond 40 meters, where trawlers are reporting drastically lower fish hauls.

Many fishermen are now facing tough economic realities. As jellyfish crowd out fish species, trawler owners struggle to cover even their fuel costs. "With lower fish hauls, many trawler owners are struggling to recover fuel costs, let alone make a profit," Rimon stated. The current situation mirrors previous years when severe jellyfish outbreaks left vessels unable to even cover operational expenses.

The alarming increase in jellyfish is a symptom of a fragile marine environment. Experts attribute the ongoing changes to several factors, including elevated sea temperatures, increased salinity, and accelerated acidification, which collectively disrupt marine habitats. Many fish species are unable to adapt to these conditions and are forced to migrate toward cooler and more stable waters. Conversely, jellyfish thrive under heightened temperatures and acidity.

A study published in Marine Environmental Research in March indicated that a warming of +1.5–3°C significantly accelerates jellyfish proliferation. Dr. Mazharul Islam, a marine researcher, noted that the rise in sea surface temperature and salinity, partly due to the absorption of carbon dioxide, directly contributes to higher jellyfish density. He added that overfishing exacerbates the situation, as it diminishes natural predators and competitors, creating a conducive environment for jellyfish blooms.

This ecological imbalance has broader implications for Bangladesh’s fishing industry, which primarily targets tuna, mackerel, sardine, and various demersal species. The deep-sea fishing sector gained traction after maritime boundary verdicts in 2012 and 2014 expanded the country's exclusive economic zone, encouraging commercial fishing in previously underexploited offshore areas. However, high fuel costs, limited cold storage, and an aging fleet leave operators vulnerable. The recent jellyfish surge is a stark reminder of how quickly conditions can change, making previously viable fishing expeditions unprofitable.

As ocean temperatures rise earlier in the year, fishermen express concerns about the potential for prolonged disruptions in their industry. Enam Chowdhury, president of the Bangladesh Marine Fisheries Association, remarked on the critical role of rainfall in reversing this trend: "If there is rain, the sea may cool and the jellyfish could disperse. But without rain, the outbreak of jellyfish may not subside quickly."

The situation underscores the complex interplay between climate change, human activity, and marine ecosystems. Scientists have long warned that climate variability, including events like El Niño, can intensify ocean warming and acidification, reshaping fish distribution and threatening livelihoods. As the Bay of Bengal continues to warm, the fishing industry faces uncertain prospects, with the balance of its marine ecosystem hanging in the balance.