The return of bluefin tuna to Northern European waters is a conservation success story, but rising sea temperatures in their Mediterranean nursery grounds mean this recovery may be short-lived, according to new research led by the University of Southampton. Temperatures expected in the Mediterranean within the next 50 years are expected to drive juvenile tuna out of the Mediterranean, where they may be accidentally caught in existing sardine and anchovy fisheries -- requiring fishery managers to adapt their methods to allow tuna nurseries to establish.

 

Outlining the research, published in Nature, lead author Clive Trueman, Professor of Geochemical Ecology at the University of Southampton, said: "We have found that anything over 28 degrees Celsius will adversely impact bluefins' growth. Drawing on compilations of global climate model projections, we show that most of the Mediterranean Sea will exceed that 28 degree threshold within 50 years under current predictions of climate change, making it too warm for juvenile bluefin. We would, therefore, expect the tuna to move their nursery areas, potentially into the Bay of Biscay or other cooler regions -- which would place juvenile tuna within existing fisheries for species like anchovy and sardine."