The Amazon River, under the moonlit sky, becomes a workplace for Josana Pinto da Costa, a fisher in northern Brazil. She navigates the river at night due to the unbearable daytime heat, a consequence of climate change.
“Climate change has had a major impact on our fishing, which is becoming increasingly difficult,” Costa remarks.
The warming climate is not just altering air temperatures but is fundamentally reshaping coastal ecosystems. Fish that were once abundant along the coast now necessitate journeys further offshore into deeper waters, explains Costa.
Costa’s situation is mirrored globally, where fishers from diverse regions like New England and the Arctic observe the ocean’s transformation. The ocean absorbs approximately 90% of the excess heat from human-induced carbon emissions, causing fish populations to move. Some fishers encounter unfamiliar fish booms, while others face disappearing stocks.
“This is the largest movement of animal life in recorded history,” says marine ecologist Dr. Malin Pinsky. The upheaval in marine ecosystems affects every part of the seafood industry, compelling all stakeholders to adapt. All must adapt.
Trouble in the Tropics
Tropical fish, accustomed to warm climates, struggle with rising temperatures. “Fish in the tropics have a smaller range of heat tolerance,” explains Dr. Juliano Palacios Abrantes, a fisheries scientist. Unlike temperate species that endure broader temperature changes, tropical fish must migrate to cooler waters.
Palacios-Abrantes’ research estimates that by 2030, 23% of fish populations crossing international waters will have relocated. The Southwest Atlantic, including Brazil, is warming faster than the global average, challenging small-scale fishers who rely on fragile ecosystems.
An audit by Oceana in 2025 revealed that 92% of Brazil’s fish stocks lack management plans. “Data on these fisheries is more important than ever,” emphasizes Oceana’s Science Director in Brazil, Martin Dias. Without proper data, the government cannot effectively prepare for climate impacts or assist fishers with necessary adaptations.
Oceana is launching a nationwide campaign to gather fisheries data to secure sustainable livelihoods for fishers. Studies show ocean heatwaves are linked to carbon emissions from 180 companies, predominantly from the Global North, yet the Global South bears the brunt of the impact. “Most countries in the Global South have contributed insignificantly to climate change, but their small-scale fishers are experiencing the worst impacts,” Palacios-Abrantes notes.
Northward Bound
In North America, fishers notice significant changes. Species like cod and lobster have shifted northward, while black sea bass, a southern species, appears in northern waters. Since the 1970s, certain species have moved northward by an average of 233 kilometers (145 miles). Some businesses have even relocated to adapt to these shifts.
In Canada, a survey revealed the salmon fishery’s decline, while other species like albacore tuna appear to be increasing. Fishers highlight the need to diversify and adapt, reporting increased stress due to uncertainty. Cultural and nutritional implications arise, especially for communities that rely on specific species for identity and tradition.
Scrambling the Sea
Fish migration will not occur instantly, but the shift is significant. “We think of a group of fish packing all their things and leaving, which isn’t how it works,” says Palacios-Abrantes. The concern lies in changes to the abundance and composition of fish populations.
Species with shorter lifespans, such as sardines, face immediate risks during spawning periods, while longer-lived species encounter chronic challenges. The introduction of predators like tuna into new habitats can disrupt ecosystems, while polar species face existential threats due to habitat loss.
The reshuffling of fish populations is not only an environmental issue but also a geopolitical one, with disputes over fishing rights anticipated. “Ecosystems are being reshuffled like a snow globe disrupting fisheries,” warns Pinsky, emphasizing the potential for conflict.
Effective adaptation requires improved monitoring and flexible policies. Palacios-Abrantes stresses the importance of revising protections and working across national borders to address environmental shifts. Communities already affected are finding ways to adapt, such as adjusting fishing practices for tuna in response to climate changes.
“Climate change adaptations need to come from communities that are being most affected,” asserts Palacios-Abrantes. Dias adds, “As the oceans change, so must we. The impacts are going to be unevenly spread across the globe. We must be quick to adapt and support fishers on the frontlines.”
Original Story at oceana.org