Fish Disappear off St Martin’s Coast as Jellyfish Raise Climate Alarms in Bangladesh
Recent observations off the coast of St Martin’s Island, one of Bangladesh’s most iconic marine ecosystems, have sparked concern among fishermen, scientists, and environmentalists. Instead of the usual catch of hilsa and other fish species, local nets are being filled with swarms of gelatinous zooplankton, jellyfish-like organisms that devour fish eggs and larvae and have rarely appeared in such abundance before.
This unusual ecological shift, observed by researchers from the University of Chittagong, may indicate broader environmental changes linked to rising sea temperatures and disruptions in the marine food chain effects that align with what climate scientists have warned for years.
An Alarming Shift in the Bay of Bengal’s Marine Life
For generations, fishermen around St Martin’s Island, a coral-rich outcrop off the coast of Cox’s Bazar have relied on the Bay of Bengal’s abundant marine life for their livelihoods. Small hilsa, flying fish, black chanda, popa and a range of other species were staples of both subsistence and commercial fishing in this area.
However, in recent days, local fishermen have reported a sharp decline in fish catches. Instead, their nets are hauling up large masses of gelatinous zooplankton, commonly referred to by locals as nuinya. These small, jelly-like organisms drift passively with ocean currents and have been observed across extensive swathes of sea near the island, a phenomenon that has not been seen before at this scale.
The sudden appearance of nuinya has prompted both concern and curiosity among fishing communities. “We used to bring home boatloads of fish just days ago,” said Abu Taleb, former president of the St Martin’s Boat Owners Association. “Now all we find are these strange jelly-like creatures. The fish seem to have disappeared.”
What Are Gelatinous Zooplankton and Why Are They Appearing?
Gelatinous zooplankton are soft-bodied aquatic organisms that resemble jellyfish but function ecologically as consumers of fish eggs, larvae and fry. Unlike most fish, they lack the strength to swim against currents and instead drift with the water flow. Their rapid increase in numbers can disrupt marine ecosystems because they consume the very food sources on which young fish depend.
Marine scientists warn that when these organisms proliferate abnormally, they can suppress fish populations by eating eggs and larvae before they have a chance to develop into mature fish. This can interfere with the natural reproduction cycles of economically important species like hilsa, which contribute significantly to Bangladesh’s fisheries sector, accounting for around 3–5 percent of national GDP and supporting millions of livelihoods.
Researchers and environmental officials are cautious, noting that the specific cause of the zooplankton surge remains unclear. Khondaker Mahmud Pasha, deputy director of the Department of Environment in Cox’s Bazar, acknowledged that there is currently no verified long-term data on whether jellyfish or similar organisms have truly increased around St Martin’s but emphasized the need for urgent research to understand the phenomenon.
Climate Change and Rising Sea Temperatures
Although clear causation has not been established, scientists point to climate change and the warming of ocean waters as likely contributing factors. Climate models and studies from South Asia and the Bay of Bengal suggest that rising sea temperatures can alter marine ecosystems, favoring species like jellyfish and gelatinous zooplankton while reducing the habitat and food availability for traditional fish species.
A recent report from the World Weather Attribution (WWA) shows that heatwaves in Bangladesh and the wider South Asian region have become 45 times more likely due to human-caused climate change, exacerbating ocean warming and contributing to extreme temperature patterns that affect both terrestrial and marine environments.
Climate change is likewise linked to extended summer heat, which has made conditions harsher for coastal and marine life while contributing to increased risks of disease for human populations. Bangladesh has experienced stresses across sectors because of warming from the surge in heatwaves and health impacts to economic losses and ecological disruptions.
Broader Environmental Impacts in Bangladesh
The changes near St Martin’s are part of a larger pattern of climate impacts sweeping Bangladesh. According to climate science research, the country’s coastal areas are increasingly vulnerable due to sea level rise, salinity intrusion, and river flow changes, all affecting agriculture, freshwater systems, and food security.
Communities in regions like Patuakhali have documented repeated cyclone and tidal surge devastation, wiping out homes, crops, and livelihoods and leaving lasting health problems and economic hardship for residents.
Bangladesh regularly ranks among the countries most exposed to climate disasters, with an average $3 billion in annual losses due to recurrent floods, heatwaves, storms and droughts affecting millions of people each year. In these conditions, coastal ecosystems become fragile, and fisheries and agriculture face heightened stress.
Human Health and Economic Consequences
The ecological disruption near St Martin’s is mirrored by health trends across Bangladesh linked to changing climate patterns. A 2025 Lancet Countdown report found that extreme heat had already cost the nation tens of billions in potential income due to lost labour productivity, with agricultural workers especially affected, reflecting how climate impacts are deeply integrated into human health and economic performance.
Climate change also worsens vector-borne diseases such as dengue fever, which health authorities and entomologists have attributed in part to changing weather patterns and extended mosquito breeding seasons. In 2025, Bangladesh saw tens of thousands infected in outbreaks that experts warn could become more frequent and widespread without urgent public health interventions.
These interlinked climate and health challenges underline how environmental shifts can ripple through communities affecting food systems, incomes, health, and national productivity.
Fisheries Sector at Risk
The decline in fish populations around St Martin’s Island carries deeper implications for Bangladesh’s fishery industry. The Bay of Bengal is a vital source of protein for millions of Bangladeshis and an economic driver for coastal communities that depend on fishing for livelihood.
With over 250 fishing trawlers operating near the island, a sustained absence of fish catch could threaten both food security and local economies unless the trend reverses. The increase in gelatinous zooplankton, if tied to broader warming trends, may require adaptive fisheries management and scientific assessments to protect juvenile fish, adult breeding cycles and habitat stability.
Need for Research, Monitoring and Adaptation
Experts agree that sustained research and improved monitoring systems are needed to understand changes in the Bay of Bengal’s marine life. This includes long-term ecological surveys, temperature and salinity tracking, and collaborations with universities and climate research institutes.
Additionally, addressing climate change impacts in Bangladesh demands integrated adaptation efforts from strengthening coastal defenses, establishing early warning systems, promoting resilient fishing practices, and investing in community livelihoods to mitigate and adapt to uncertainties.
The government has recognised these threats with both policy measures and financial allocations in the 2025–26 budget, directing funds to tackle air, water and soil pollution, waste management, coastal ecosystem protection, and climate resilience planning.
A Marine SOS for Bangladesh
The unusual proliferation of gelatinous zooplankton and disappearance of fish around St Martin’s Island is more than a local oddity. It is a potentially early warning of how climate change is reshaping marine ecosystems, threatening livelihoods, and intersecting with broader economic and health challenges across Bangladesh.
While the exact causes remain under investigation, the convergence of rising sea temperatures, disrupted food chains, and extreme weather impacts underscores the urgency for scientific research, climate adaptation, and coordinated policy action. As Bangladesh confronts these intertwined environmental threats, the tale of disappearing fish and rising jellyfish off St Martin’s coast serves as a poignant reminder of the stakes of a changing climate.
