Spanish Fishers in Galicia Say Shellfish Stocks Are Collapsing Due to Climate Change

Spanish fishers in Galicia — Europe’s main source of shellfish and the biggest producer of mussels in the world —  are reporting a “catastrophic” collapse in shellfish populations due to the climate crisis.

Some shellfish stocks have plummeted by 90 percent in just a few years, reported The Guardian.

The clams and cockles local residents depend on and have been harvesting for years are disappearing fast. Extreme weather events like torrential rain and heat waves have become more intense and frequent due to climate change, threatening the region’s marine species.

Spanish fishers in Galicia report ‘catastrophic’ collapse in shellfish stocks

[image or embed]

— The Guardian (@theguardian.com) January 28, 2025 at 12:18 AM

“Either the shellfish adapt, or they die, and us too,” said Patricia Piñeiro, who harvests clams in the small fishing town of Cambados, but has been having an increasingly difficult time finding ones big enough to harvest, as Mongabay reported. “They’re just too small.”

Piñeiro held a measuring device provided by local fishing authorities that was set to 1.5 inches — the minimum size for harvesting the bivalves.

There has been a steep decline in clams, mussels and cockles, according to a fishing website, reported The Guardian. The cockles and clams are collected at low tide by hand, while mussels are taken from the ocean on ropes attached to wooden rafts.

Cockle numbers fell by 80 percent in 2023, compared with the year before, while some clam varieties dropped by 78 percent. Oyster production has seen a slight increase.

Mussel production in 2024 was the lowest in 25 years, falling to 178,000 tonnes from 250,000 tonnes in 2021.

“Extreme climate events, such as heatwaves and torrential rain, affect the physiology and functioning of marine species, especially in estuarine habitats, producing severe ecological and socioeconomic impacts when the affected species support important fisheries, such as artisanal shellfisheries,” said a 2023 analysis, “Assessment of Risks Associated with Extreme Climate Events in Small-Scale Bivalve Fisheries: Conceptual Maps for Decision-Making Based on a Review of Recent Studies,” published in the Journal of Marine Science and Engineering.

María del Carmen Besada Meis, head of the San Martiño fishers association in Ría de Arousa, believes climate change is to blame. The past two years have brought above-average rainfall to the region, with recent torrential rains lowering the water’s salinity.

“But we don’t have enough concrete evidence and what we’d like is for someone to come and do some proper research so that we know what’s behind this and what we can do about it,” Besada Meis said, as The Guardian reported. “We’re marisqueros (shell fishers) and we don’t know what the solution is, which is why [we] need scientists to help us with this. The government needs to put some money on the table for this research.”

Marta Martín-Borregón, coordinator of Greenpeace oceans in Spain, described the recent figures as “catastrophic.”

“The biggest cause is pollution from waste discharged into the estuary, from agriculture and from factories, such as the fish canneries,” Martín-Borregón said.

Plans to open a copper mine and build a cellulose plant could potentially produce more waste and use enormous amounts of water.

The water company in Galicia said waste was dumped into the sea over 2,000 times each year, 10 percent of which exceeds legal toxicity limits.

Martín-Borregón said, though pollution is a huge problem, the main culprit is climate change.

“The waters of the rías are normally cold and the currents bring a lot of nutrients. With warming seas there are species of shellfish that can’t thrive in warm water,” Martín-Borregón explained. “This is especially the case with mussels and as the temperatures rise the shellfish industry is moving closer towards collapse.”

When dams are opened during low tide, the rías is flooded with freshwater, reducing salinity and leading to massive mortality events for bivalves, especially cockles.

Invasive species like the blue crab — a western Atlantic and Gulf of Mexico native — are also attracted to the warmer waters. Blue crabs feed on local species such as velvet and spider crabs, which have high market value.

“We can’t make a living like this,” Besada Meis said. “We carry on working but we’re living on social security.”