Mongabay Series: Oceans
Reporting for this story was supported by Journalismfund Europe under the Earth Investigations Programme.
GALICIA, Spain — The first sleepy rays of morning light are starting to illuminate the beach of Cambados, a small Atlantic-facing town in the Spanish region of Galicia that’s famous for its shellfish and Albariño wine. It’s a rainy morning in March and the mariscadoras — women shellfish pickers — are wading straight into the ocean armed with buckets and rubber boots for another day of work.
But the clams and cockles their livelihood depends on are increasingly hard to come by. Extreme weather events made more frequent and intense by climate change, including heat waves and torrential rain, threaten various marine species in the region, and with them, the tradition that has been passed down through generations of women.
“Either the shellfish adapt, or they die, and us too,” says Patricia Piñeiro between wind gusts and rain as she searches for clams big enough to harvest.
“They’re just too small,” she says, showing the measuring device from the local fishing authorities set to 4 centimeters (1.5 inches), which means she must return most of the clams she finds to the ocean.
“At this pace, the almeja fina [Ruditapes decussatus] and almeja babosa [Venerupis corrugata] will disappear,” says Maria José Cacabelos Domínguez, a retired mariscadora who now organizes tours for people wanting to see the shellfish pickers in action.
Most mariscadoras are between 40 and 60 years old and started out decades ago when shellfish stocks were still abundant. It’s one of the few jobs that can be combined with caretaking duties in this still-traditional and patriarchal region, says Sandra Amézaga, the spokesperson of Mulleres Salgadas, an association of women in the fishing sector. The lack of shellfish is now pushing many to take precarious, informal jobs cleaning hotels or working in bars, she adds.
Besides sustaining livelihoods, shellfish play a vital role in regulating marine ecosystems. As filter feeders, they clean the water they live in by removing nitrogen, phosphorous and carbon, making them an environmentally sustainable source of nutrient-dense protein.
A 2023 study from the local University of Vigo shows that the four main species of clams and cockles harvested in Galicia, including almeja babosa and almeja fina, are already in sharp decline. While the non-native almeja japónica (R. philippinarum), introduced for its adaptability, has proved to be more resilient to rising temperatures, it, like the others, is vulnerable to prolonged periods of low salinity caused by heavy rains.
In 2023, just before Christmas — the most lucrative season for shellfish — unusually warm temperatures coupled with intense rainfall caused a mass mortality event that reportedly killed around 95% of Galicia’s cockles (Cerastoderma edule) and 75% of almeja japónica. Local government fish market data show a steep decline in shellfish sales following the December events, and stocks still haven’t recovered.
Offshore to the north, on Illa de Arousa, shellfish pickers face the same struggle. “The few clams we manage to find aren’t growing,” says Inmaculada Rodriguez, head of the local mariscadora association, who started shellfishing alongside her mother and aunts when she was 14. “I remember pulling out clams the size of my fist.” Today, around 3,500 shellfish pickers hold a license to operate, half as many as in 2001.
Following the disastrous December, many of Galicia’s shellfish associations temporarily ceased activities to help stocks recover. That includes the mariscadoras from the nearby town of Vilanova de Arousa, who haven’t worked since. They now receive a little more than 1,000 euros ($1,073) a month in government support, says María José Vales Martínez, who previously headed the town’s fishing guild. However, the requirements are strict — those working a second job are often denied compensation — and payments are often delayed, Amézaga says.
While the 6 billion euro ($6.43 million) European Maritime, Fisheries and Aquaculture Fund is supposed to “guarantee … the livelihood of coastal communities,” the more than 1 billion euros ($1.07 million) given to Spain isn’t reaching the artisanal producers most in need, according to Amézaga. The shellfish pickers Mongabay spoke to say complex application processes make the funds hard to access despite clear guidelines stating that EU countries “must endeavour to introduce simplified procedures for small-scale coastal fishing businesses applying for EMFAF support.”
Rodriguez and her fellow mariscadoras of Illa de Arousa were among the last to quit working, and they are now in the process of applying for monthly government support. At the moment, they are struggling to pick even 1 kilogram (2.2 pounds) of almeja japónica.
“What do you do with 1 kilo [of clams]? You can’t even pay your social security fees at the end of the month,” Rodriguez says. “[A] lot of people have already left to go work on land because this is unsustainable.”
Mass mortality events such as the one in December are likely to become more common as global warming disrupts rainfall patterns. “Here in Galicia, we’re used to the rain. The problem is when that rain accumulates over a few days,” says Elsa Vázquez, a University of Vigo zoologist who studies how changes in salinity and temperature affect the main shellfish species harvested in Rías Baixas, the four productive estuaries in southwestern Galicia.
Torrential rainfall increases the amount of freshwater flowing from the river mouths into the estuaries, where the shellfish banks are located. Prolonged periods of low salinity affect bivalves’ ability to breathe, feed, grow and reproduce. Shellfish can close their valves during periods of low salinity to protect themselves, but this uses up precious energy and weakens them, Vázquez says.
Between October and November 2023, Galicia’s weather agency recorded more than 30 consecutive days of rainfall yielding more than 1,000 liters of rain per square meter (264 gallons per 10.7 square feet) — 127% more than normal. “According to our experiments, salinity below 15 parts per thousand for several days causes mortality, and this winter there were many days when salinity was as low as five parts per thousand,” Vázquez says.
The emptying of reservoirs during low tide by electricity companies also alters the estuaries’ delicate balance. According to the Platform for the Defense of the Ría de Arousa, a conservation NGO, the release of water should be timed to coincide with high tide to avoid freshwater inundating the shellfish banks.
As worrying as low salinity are marine heat waves, which are likely to trigger mass mortality events affecting an increasing number of species and habitats, the EU’s Copernicus weather institute says. In both August 2023 and January 2024, the world’s ocean temperatures reached an unprecedented average of 21.1°C (70°F), a clear sign of global warming with significant implications for biodiversity.
Intertidal shellfish species bury themselves in the sand to keep cool, but with heat waves becoming more intense the heat penetrates deeper, making it impossible to escape. Any survivors are severely weakened, which affects their growth and reproductive capacity, Vázquez says.
Other variables, such as sea level rise and pollution from local industry, also play a role. Every centimeter (0.39 inch) of sea level rise means a loss of about half a meter (1.65 ft) of coastline, submerging sandbanks for longer, says Silvia Torres López, an oceanographer at the Centro Tecnológico del Mar, a research institute in Vigo. “Pollution is still a great unknown. … We need to keep monitoring all these factors,” she says. Plans to build a textile factory in the area, which shellfishers and ecologists fear could further damage the ecosystem, are currently being debated in Galicia and at the EU level.
Numerous shellfish pickers told Mongabay they want the Galician government to fund an in-depth study on the impacts of climate change to help inform potential solutions. Scientific models suggest 2060 could be a global tipping point for shellfish in many regions of the world, with fisheries in Spain at high risk due to low species diversity and vulnerability to increased temperatures.
The development of clam hatcheries could be a solution. While some commercial hatcheries exist for almeja japónica, growing baby clams to be planted out on sandbanks, more research is needed to cultivate almeja fina and babosa profitably, Vázquez says. She describes this as “the future of shellfishing” for its potential to establish enough reproducing adult shellfish to get stocks back to normal.
Another solution being explored is the real-time monitoring of salinity, temperature and other variables in the shellfish banks. This could help researchers create predictive models so mariscadoras could prepare for periods of low salinity and high temperatures, Vazquez says, adding that it would require dedicated government funding and support.
With the warm summer months at hand, the mariscadoras are left with the few kilos of almeja japónica they manage to find. Vales Martínez has worked as a mariscadora for 24 years, just like her mother and grandmother before her. But like many of her colleagues, she’s worried about the future.
“What’s really needed is to invest in the sea, even if it means closing it for a year while stocks recover,” she says. ”We need to address the root causes of the problem, because if the estuary dies, we all die.”
Banner image: A mariscadora uses a clam rake to dredge for shellfish off Cambados in Galicia. Image by Naomi Mihara for Mongabay.
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Citations:
Domínguez, R., Olabarria, C., & Vázquez, E. (2023). 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. Journal of Marine Science and Engineering, 11(6), 1216. doi:10.3390/jmse11061216
Carss, D. N., Brito, A. C., Chainho, P., Ciutat, A., de Montaudouin, X., Fernández Otero, R. M., … Jones, L. (2020). Ecosystem services provided by a non-cultured shellfish species: The common cockle Cerastoderma edule. Marine Environmental Research, 158, 104931. doi:10.1016/j.marenvres.2020.104931
Des, M., Fernández-Nóvoa, D., DeCastro, M., Gómez-Gesteira, J., Sousa, M., & Gómez-Gesteira, M. (2021). Modeling salinity drop in estuarine areas under extreme precipitation events within a context of climate change: Effect on bivalve mortality in Galician rias Baixas. Science of The Total Environment, 790, 148147. doi:10.1016/j.scitotenv.2021.148147
Stewart‐Sinclair, P. J., Last, K. S., Payne, B. L., & Wilding, T. A. (2020). A global assessment of the vulnerability of shellfish aquaculture to climate change and ocean acidification. Ecology and Evolution, 10(7), 3518-3534. doi:10.1002/ece3.6149
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