A new study by an international team of scientists, published in Nature Ecology & Evolution, warns that many large fish species, including many of the sharks and rays of Europe, are threatened with extinction. Confirming the findings of previous studies, the scientists highlight regional differences in fish stock status in Europe and point to overfishing in the Mediterranean.
Marine fish play an important role in marine ecosystems, but are also a major food source for marine animals and humans. The new study published in Nature Ecology & Evolution found that the bigger the fish, the more likely it is to be threatened with extinction. This is because they are more susceptible to threats such as overfishing because they grow slower, take longer to mature, have fewer offspring and are in higher demand for food consumption and recreational fishing.
The research team studied the status of commercial fish stocks all around Europe to assess the extinction risk of fish. The JRC contributed to the study by analysing stock assessment data of commercial fish stocks in the Mediterranean Sea. The Mediterranean stock assessment data were produced by the Scientific, Technical and Economic Committee for Fisheries (STECF), a Commission expert group for which the JRC acts as the secretariat and provides expertise in stock assessments.
Geographical discrepancies: Mediterranean worst off
The scientists found significant geographical discrepancies: a much higher fraction of the fish stocks were overexploited and depleted in biomass in the Mediterranean, compared with the northeast Atlantic. None of the 39 assessed Mediterranean fish stocks examined were classed as sustainable. Hake (Merluccius merluccius) is of particular concern: of the 12 examined hake stocks in the Mediterranean, 9 have exploitation rates that are over five times higher than the rate in line with maximum sustainable yield.
Scientists say that this is linked to how the areas are managed, how fishing quotas are set and how fish stocks are monitored. They also remind that the Mediterranean is a semi-enclosed sea with a much longer history of human impacts compared with the Atlantic. At present, the Mediterranean is heavily impacted, in addition to fishing, by multiple stress factors ranging from temperature increase and acidification to habitat modification and pollution in the coastal areas.
Larger fish species threatened with extinction
The study stresses that while most of Europe’s commercial fish stocks are not yet threatened with extinction, most of the larger fish species are, particularly sharks and rays. In addition to these, the large fish species that are threatened include six species of sturgeon, the northern wolffish (Anarhichas denticulatus), blue ling (Molva dipterygia), the dusky grouper (Epinephelus marginatus), the Atlantic halibut (Hippoglossus hippoglossus) and (wild) Atlantic salmon (Salmo salar).
“This study highlights two major issues for Europe’s fish: the threats to large fish species, including sharks and rays, and the severe overfishing in the Mediterranean, which is in contrast to the improving picture in the northeast Atlantic. In the northeast Atlantic, there are catch limits in place, coupled with rigorous fisheries monitoring and enforcement schemes. In the Mediterranean there is a larger number of fishing vessels using multiple gears, there are largely no catch limits, and management is carried out mainly through some spatial and temporal restrictions to fishing, which are often poorly enforced. The Commission recently launched the MEDFISH4EVER strategy to improve the state of Mediterranean fish stocks, which is obviously a step to the right direction”, said JRC researcher Paris Vasilakopoulos, co-author of the study, who contributed to the analysis of the Mediterranean fish stock assessment data
Greater efforts to conserve our large fish species are essential as the loss of these large, ecologically important species could have consequences that cascade to other levels which include important commercial species, particularly in the overfished southern European stocks.
In recent years, the European Commission has taken a number of initiatives to redress the balance between harvesting activities and productivity of the stocks. Modern EU rules against overfishing apply domestically, and the Commission works closely with non-EU Mediterranean countries through international channels like the General Fisheries Commission for the Mediterranean, the International Commission for the Conservation of Atlantic Tunas and the Barcelona Convention. In parallel, a number of conservation actions are now being developed through regions-specific initiatives for the Adriatic-Ionian and for the western Mediterranean. A positive sign also comes from the recent Declaration on the sustainability of Mediterranean fisheries signed by 15 fisheries ministers of riparian countries (MedFish4Ever). The countries in question undertake to improve fisheries governance in the region by upgrading data collection and scientific evaluation, establishing an ecosystem-based fisheries management framework and developing a culture of compliance to combat illegal, unreported and unregulated fishing. This new 10-year long partnership, which could still extend to even more countries, is set to bring us closer to our goal of a healthy and productive Mediterranean Sea.
The research team, which was made up of 44 researchers from all around the world, received funding from the European Commission and the Marine Alliance for Science and Technology Scotland (MASTS) to carry out the study. The study was part of a major effort to assess the extinction risk of fish carried out by the International Union for Conservation of Nature (IUCN) to produce the European Red List of Marine Fishes and saw the team assess over 1000 different species and the status of commercial fish ‘stocks’. Further to this, the team aimed to find out if their data agreed with advice received from other government fisheries agencies.
The results of the study confirm the observations made in a recent report published by the Joint Research Centre together with the European Academies Science Advisory Council (EASAC), which points to the overexploitation of high trophic levels (“big fish”) and generally a suboptimal exploitation of marine living resources for food.
The JRC supports the transition towards sustainable fisheries through dedicated research and the provision of scientific advice to the Common Fisheries Policy. This includes the assessment of stocks in the Mediterranean and the conservation of sharks and rays, for instance through the MedBlueSGen project, which is a population genetic study on Mediterranean blue sharks for stock identification and conservation, carried out by the JRC in collaboration with 7 European research institutions.
Reference: Fernandes, P.G., Ralph, G.M., Nieto, A., Criado, M.G., Vasilakopoulos, P. et al. Coherent assessments of Europe’s marine fishes show regional divergence and megafauna loss. Nature Ecology and Evolution 1, 0170 (2017).