Spain: Small-scale fisheries stand to gain and to lose from climate change

by Thomas Jensen

Adaptation is not straightforward

This article was featured in Eurofish Magazine 2 2024.

In many coastal villages small-scale fisheries play an important role in terms of nutritional security and employment, as
well as from a social and cultural perspective. Developments, such as climate change, that affect them negatively can therefore also threaten their communities. A better understanding of the impacts of global warming will help the small-scale sector adapt.

Small-scale fisheries (SSF) are defined as fishing carried out by vessels less than 12 m in length and not using towed fishing gear. Instead, small-scale fishers use mainly trammel nets and set gillnets, pots, set longlines, and hand lines. They usually operate within 12 nautical miles of the coast close to landing points and one vessel may use multiple fishing gears. According to the latest STECF report1, in 2021 the EU small-scale fishing fleet amounted to about 41,300 active vessels or just over three quarters of the entire EU active fleet. The number of workers in the sector was 60,000 people accounting for half the total employment.

Small-scale fisheries are important for many reasons

The SSF thus play an important role in providing employment and food security and are a source of healthful proteins with a relatively low carbon footprint. In small coastal communities, SSF are often the social and cultural backbone of the community in addition to contributing to its economic welfare. The small-scale fleet is usually sustainable in its operations as fishers use selective gears avoiding overfished species and minimising bycatch. Given their economic and social significance, any disruption to the SSF can have knock-on consequences for the communities in which they are embedded. Unfortunately, climate change is one such disrupting mechanism that small-scale fishers face. Although the SSF is heavily skewed towards the Mediterranean region, which accounts for 42% of the total value, coastal fishing vessels are found in all European sea basins. According to Arantza Murillas from AZTI, a research institute in the Basque country, an autonomous community in northern Spain, the small-scale segment in the Basque fleet comprises vessels with a length of less than 15 m that fish in the vicinity of the ports along the Basque coast, where they also land their catches. They typically carry a crew of one to three people and use different gears (trammel nets, traps for cephalopods and crustaceans, longlines and hand lines) targeting different species during the year. Among the most common are Atlantic mackerel, albacore, European hake, European conger, Atlantic tuna, red mullet, and anglerfishes, but they land more than 100 species in total.


Guillem Chust, Head of Global Change in Marine Ecosystems at AZTI speaks of the signals scientists have identified that indicate changes in climate. One of these is the rate of warming in the Bay of Biscay, a metric that has been updated each year since the 80s and which clearly shows that the surface of the sea is getting warmer at a rate of about 0.2 degrees per decade. While this is focused mainly in the central part of the bay, scientists have noticed that the temperature on the Basque coast is ­increasing faster. The rise in the water temperature is what affects the fish most. Other indicators such as rising sea levels has not had such an impact on fisheries nor has acidification—as far as we know, Dr Chust cautions. But scientists have related warming water to the distribution, phenology (the timings of cyclical or seasonal biological events), and to the size of fish, though not all species respond in the same way. Studies of Atlantic mackerel, for example, revealed that spawning was shifting towards the north pole to compensate for this warming. Horse mackerel, on the other hand, compensate by bringing the spawning season forward. The peak of this species’ spawning is in the spring and this is brought forward by one or two weeks, or more precisely, by twelve days per decade. This strategy is not unique to horse mackerel, it is also seen in anchovy. The impact on body size can be seen because the size of the adults is lower in warmer waters such as the Mediterranean, the Bay of Biscay, and the north of Africa and larger in cooler waters such as the North Sea. The reduction may, however, also be influenced by other factors such as abundance, and in other species, by fishing effort. But Dr Chust points to experimental work that has shown that metabolism changes with temperature affecting the growth and the body size. This effect is seen not only in fish, but in all cold-blooded animals.

Fish distribution, ­spawning period, and size can all change as waters warm

In terms of the impact on the fisheries it is not clear-cut. The Atlantic mackerel may move some hundreds of kilometres for each degree of warming, but it has a natural range of thousands of kilometres, so teasing out the impact of the warming compared with other environmental variables is currently tricky. Dr Chust expects the impacts to become more explicit over the next 20-50 years. The fishing sector can start to adapt to different geographic ranges, changes in phenologies such as spawning periods, and in body size. Shifting geographic ranges of key species could also be a source of conflict between states as quotas would need to change to reflect the new geographic range of the fish. Another way that fish can respond to higher water temperatures is by inhabiting deeper water. Studies have shown that a lot of marine species do this and in the medium term the fishing sector would have to adapt. So far while a lot of resources are going into efforts to try and better understand the impacts of climate change on stocks, Dr Chust has not noticed any new regulations being enacted. But there is no doubt that mitigation strategies such as reducing greenhouse gas emissions must be implemented by the fleet just as other transport sectors are trying to decarbonize. The sustainable management of stocks is one way of making them more resilient to the impacts of climate change. By protecting different ecosystems, seagrass, or mangroves, for instance, or through marine protected areas where fishing pressure is restricted, policymakers can help stocks reproduce and thrive which in turn produces benefits for fisheries at least in the midterm.

Among the impacts of global warming is the spread of tropical species to temperate areas where they are normally only seldom seen. Dr Chust and his colleagues have been analysing communities of species in different parts of Europe and have found that species that are adapted to warmer regions but that have always been present in European waters are increasing their abundance, while the frequency of those species that are adapted to colder place is decreasing. In other words, the composition of the species communities is changing which could change the local fisheries. In the Mediterranean, which is a semi-enclosed water body, the fish can migrate, but they remain geographically attached to areas in the sea where they spawn. The scientists have used several ecological models coupled with physical models which has deepened their understanding but not enough for them to predict how the fish will respond to warmer water in their spawning areas. The Mediterranean faces a severe problem with climate change with a rate of warming that is two to three times that of the Bay of Biscay. This combined with the fact that it is semi-enclosed, exacerbate the challenges of warming water. In addition, the salinity of the water is expected to increase as evaporation exceeds precipitation, acidification is also expected to worsen, and the thermocline will change. Normally, says Dr Chust, the new conditions would allow species that thrive under these circumstances to occupy the niches abandoned by species that migrate away. But the semi-enclosed nature of the Mediterranean makes it more challenging for new species to enter and old ones to leave and scientists are not yet quite sure how this will play out.

More knowledge needed to help the sector adapt

For the small-scale fisheries the consequences of climate change are likely to vary widely with some fisheries benefitting from new and (potentially) valuable species that move into fishing areas, while others struggle with declining catches as traditional species disappear. The small vessels used by the sector do not permit fishers to switch to other areas more distant from their home ports which constrains their opportunities to adapt. As scientific insights into global warming and its consequences deepen, policymakers will be better equipped to tackle the challenges facing small-scale fisheries helping them to adapt.

You may also like