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).