Two coasts, one struggle for octopus fishers battling overfishing and warming waters

ASTURIAS, Spain, and YUCATÁN, Mexico — On a mild February morning, Isaac Blanco quickly places half a sardine into each cage as his brother, Julio, steers their boat along the Asturian coast in northern Spain. This is the beginning of the season for pulpo — Octopus vulgaris — the most commercially sought-after cephalopod in this region, and part of the local fishing tradition.

The fishing villages along this stretch of the Asturian coast have long been a model of sustainable fisheries. In 2016, a fishery of 33 artisanal boats called Arpesos became the first in the world to earn an eco-certification from the U.K.-based Marine Stewardship Council (MSC) for octopus fishing. These fishers employ a technique that’s widespread on the Mediterranean and Atlantic coasts of Europe and Africa. A selective fish trap called a nasa in Spanish consists of a plastic-steel cage with fish bait inside. Once an octopus enters the cage, it can’t easily exit, and when fishers pull the trap back on board, they can throw any octopus smaller than the legal size back into the sea alive. The same goes for unintended bycatch, like sea stars, crabs or small fish. The technique has existed since ancient times, but nowadays it’s becoming less common, with fishers often using bottom trawlers instead to catch octopus. Julio told Mongabay that prior to attaining MSC certification, they struggled to earn enough because cheaper imports entering Spain kept prices low.

A combination of overfishing, climate change effects and generational turnover has caused a general decline in fishing activity in Spain. The country’s own fleet supplies less than 10% of the roughly 75,000 metric tons of octopus it imports, mostly from West African nations and Mexico, according to the European Market Observatory for Fisheries and Aquaculture Products. Despite the decline, the presence of traditional fishing guilds called cofradías in the Asturias region provided a well-established, community-based governance system capable of organizing fishers and implementing collective rules that laid the groundwork for achieving MSC certification.

After two hours of waiting, Julio Blanco turns on a small motor to haul in the nasas, strung on a common line. Behind him, Isaac removes octopuses from the traps and quickly gauges their size. “With MSC certification we have strict rules to follow,” Julio tells Mongabay. “But for the first time, we’re seeing higher profits. We’re catching fewer kilos, but earning more.”

This year, catches seem lower than usual. Julio suggests it could be due to a combination of warming waters and overfishing by local trawlers not certified by MSC. Data from the Global Fishing Watch vessel-tracking platform confirms that one heavily targets an area local fishers say is an important octopus breeding ground.

“All fishing gears are destructive, but trawlers are by far the worst,” Julio says. The method is widely criticized for fishing indiscriminately and destroying habitat.

With a cap of 125 traps per fisher, the 33 Arpesos fishers had the initiative to find more profitable channels — a rare achievement in the world of artisanal fishing. MSC certification allowed them to command higher selling prices, which meant they could stay profitable without falling into overfishing, even with the lower catches this season.

This situation seems ideal to other fishing communities facing similar challenges that often lead to overfishing or illegal fishing: high market-driven demand and competition from fishers using less sustainable methods. Some are pursuing eco-certification as a solution. But while this may offer a lifeline to the fishers’ economies, it may only work well for the octopus populations when all fishers in an area join in, and that’s not always possible, experts say. Moreover, factors beyond fishers’ control, like warming waters, may affect the fishers and the octopuses alike.

José Luis Acuña Fernandez, an ecologist at the University of Oviedo in Asturias, is familiar with the Arpesos fishery. He studied Asturias’s octopus population and helped develop a model to inform sustainable fishing of it. The species today is not overexploited, Acuña tells Mongabay, although data show that the stock has declined over the last two fishing seasons, in 2024 and 2025. “To me, MSC is not a label indicating sustainability, but rather a label that indicates a direction towards sustainability,” he says. “There are ecological complications that go beyond any certification. Like the change of water temperature and other fishing activities happening in the same area.”

Is the Asturias fishery a model for Yucatán?

Across the Atlantic Ocean, on the sun-drenched coast of Mexico’s Yucatán Peninsula, the Alianza por el Pulpo en Yucatán, a group of octopus fishers, exporters, cooperatives and scientists with the Mexican Institute for Fisheries and Sustainable Aquaculture Research (IMIPAS) is engaged in a fishery improvement project (FIP) that after six years is now entering the MSC’s assessment process for certification.

Mexico is the world’s third-largest octopus producer, representing 9.9% of total global production. The Yucatán fishery produces at least 65% of this, mainly exporting two native species, O. maya and O. americanus — often sold as O. vulgaris — to countries like Spain, Italy and the U.S.

Unlike the Asturias fishery, the Yucatán one has been affected by a complex illegal fishing situation in recent years. This has resulted in a worrying decline of octopus landings that in 2023 forced artisanal cooperatives in the state of Campeche to suspend operations completely.

The Alianza members know obtaining a certification won’t curb illegal fishing by itself, but they have become more aware, organized and connected, thanks to the meetings and workshops they regularly hold with the assistance of COBI, the Mexican NGO that helped them create the FIP in 2019.

As of February, the FIP’s estimated landings (2,633 metric tons annually) represent about 10% of the total octopus fishery’s landings, according to FIP reports. Long-running efforts to increase its cooperation with authorities bore fruit in June, when the FIP, community representatives and government authorities established a joint advisory committee to support the MSC assessment.

“The push for sustainable certification is setting a precedent to promote the use of the artisanal method as the predominant standard in the fishery,” biologist Miguel Ángel Gamboa Álvarez, a former IMIPAS researcher who advises the FIP, tells Mongabay. “For the first time, I see science truly applied to the sector. Fishers are collecting and sharing data regularly, new measures are improving the fishery, and research efforts are expanding.”

Gareteo, the artisanal fishing method the FIP aims to certify, is highly selective, with a low impact on the octopus population. Fishers attract the octopus with crab bait tied on lines. After the octopus grabs hold of the bait, the skilled fisher pulls in the handline at a speed that won’t scare it away. Once it reaches the boat, the fisher measures it to ensure it meets the minimum legal size before killing it, throwing undersized octopuses back into the sea unharmed. The method protects females, which hide among rocks during egg hatching.

This unique fishing technique has been abandoned by young fishers and those unrooted to the Yucatán coast, who often find it slow and hard to master. Instead, many fishers rely on diving with air compressors and metal hooks to grapple octopus from artificial caves placed to lure them. The practice is unsafe, illegal and indiscriminate, because it targets undersized octopus and brooding females. The resulting overfishing has compromised the available stock in Campeche, forcing fishers to go farther out to sea to find better catches.

Luisa Marnely, administrator of the Chichan Cuch cooperative in the town of Celestún, says the collective effort happening in Yucatán is vital. “Authorities don’t support us, we’ve reported the illegal practices, but our claims remain unheard and illegal fishers keep operating,” she tells Mongabay. “That’s why we value the assembly’s work and hope the workshops organized by the FIP will lead to real change.”

Katina Roumbedakis, a biologist with the Yucatán research institute Cinvestav Mérida, has studied octopus fisheries in northern Spain, Portugal and now Yucatán, reviewing the scientific literature to understand how sustainability standards are set in different countries. She says certification schemes are good initiatives toward sustainability, but the Mexican government’s capacity to monitor and stop illegal fishing is limited. Last year, only 11 fisheries agency inspectors worked across the entire peninsula, with help from the navy for monitoring and seizure operations. The MSC assessment will evaluate the whole fishery, though only 20% of the boats in it are currently involved in the FIP and therefore eligible for potential certification.

In Roumbedakis’s view, the Yucatán octopus fishery as a whole cannot be considered sustainable as long as certified and noncertified fishers target the same stock. “It is definitely true that it is positive for fishers to earn more per each kilogram they catch, but it’s difficult when the boat next to theirs is fishing many times more than what they are fishing, without any certification, and perhaps illegally. Can we still talk of real sustainability in this case?” she says.

Warming waters bear an uncertain future

Overfishing is not the only threat to octopus populations. Rising water temperature is likely to cause their migration to colder waters, either at greater depth or higher latitude, as has unfolded on the French coast. “While catches in Portugal and Spain have dwindled in recent years, octopus landings have increased up to tenfold further north along the same Atlantic coast, in France, particularly in the Bay of Biscay,” Julio Agujetas, senior fisheries manager at MSC Spain/Portugal, tells Mongabay.

Fishery actors in the three countries are now proposing an increase in the national minimum size in an effort to boost the octopus population along the Portuguese and Spanish coasts, where O. vulgaris has traditionally been fished.

When it comes to this year’s unusually low catches in Asturias, it’s “highly unlikely” that fishing pressure is the cause, because scientific stock assessments suggest catch quotas are sustainable, says Maria del Pino Fernandez Rueda, head of the Inland Waters Fisheries Department at the Fisheries Experimentation Center in Asturias. One explanation, she tells Mongabay, “could be the influence of oceanographic events that may have affected the survival or reproduction of octopuses, during this season or the previous one.”

In 2023, Asturias water temperatures rose to 24° Celsius (75° Fahrenheit) for the first time, well above the usual range of 18-22°C (64-72°F). The same year, waters in Yucatán reached 30°C (86°F), their warmest on record.

“With Octopus Maya, we’ve observed that their thermal limit is around 27°C [81°F],” Carlos Rosas Vázquez, a researcher at the National Autonomous University of Mexico in Sisal, Yucatán, and a member of the Cephalopod International Advisory Council, tells Mongabay via email. Rosas maintains that the decline of nearshore catches is due more to the warming waters than to the illegal fishing.

A recent modeling study predicted a significant loss of suitable habitat for O. americanus near the equator, with limited potential for expansion toward the poles. This could lead to its disappearance from its current range in Mexico, without sufficient habitat available at higher latitudes.

In both Asturias and Yucatán, adaptation is crucial for fishers, since reliance on octopus catches is getting riskier with more frequent thermal anomalies. The Blanco brothers are storing their nasas early this year. Although their fellow fishers are still going out to sea after octopus, Julio and Isaac say they prefer to wait for better times, and fish other species. “My brother and I will go after sea urchins now,” Julio says. “To diversify our fishery, some of us go after one species, some after another one. We have to share our resources among the cofradía.”

Reporting for this story was supported by the Pulitzer Center’s Ocean Reporting Network, where Davide Mancini is a fellow.

Banner image: Julio and Isaac Blanco fish octopus along the coast of Asturias, Spain, using traditional nasas cages. Image by Davide Mancini.

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Citations:

Borges, F. O., Guerreiro, M., Santos, C. P., Paula, J. R., & Rosa, R. (2022). Projecting future climate change impacts on the distribution of the ‘Octopus vulgaris species complex’. Frontiers in Marine Science, 9. doi:10.3389/fmars.2022.1018766

Roa-Ureta, R. H., Fernández-Rueda, M. D., Acuña, J. L., Rivera, A., González-Gil, R., & García-Flórez, L. (2021). Estimation of the spawning stock and recruitment relationship of Octopus vulgaris in Asturias (Bay of Biscay) with generalized depletion models: Implications for the applicability of MSY. ICES Journal of Marine Science, 78(6), 2256-2270. doi:10.1093/icesjms/fsab113

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