New research led by the RSPB shows that UK seabird populations could be affected by the amount of a critical fish species caught in the North Sea by an industrial fishery, highlighting the importance of continuing to work with other countries on fisheries management after leaving the European Union.
The study suggests a link between the amount of sandeels caught by fishermen and the breeding success of kittiwakes (a small species of gull, currently red-listed in the UK), with higher intensity fishing leading to lower numbers of chicks being produced.
In the North Sea, sandeels provide a vital food source for breeding seabirds but are also the target of an industrial fishery conducted mainly by Denmark. Tracking data of individual breeding kittiwakes by RSPB scientists indicates that the most productive sandeel fishing grounds, an area known as the Dogger Bank, overlap with foraging areas of kittiwakes from eastern English colonies, raising the prospect that the fishery could adversely affect the birds' populations.
The Dogger Bank is the largest sandbank in the North Sea, straddling the waters of the UK (about 100 miles off the Yorkshire coast), Netherlands and Germany, and supporting a high density of sandeels.
The RSPB's Principal Conservation Scientist, Dr Mark Bolton, said: "Using small tracking devices known as 'GPS tags', we followed individual kittiwakes from colonies at Filey and Flamborough in Yorkshire to see where they went to feed during the breeding season. We found that they went much further from the coast than we had previously realised, and were often actually travelling all the way to the Dogger Bank to catch these small fish known as sandeels for themselves and their chicks. This added up to more than a 200km round trip each time".
Using data collected between 1986 and 2014, the RSPB found that higher kittiwake breeding success at colonies was correlated with lower sandeel fishing intensity. This suggests that, at times over the last 30 years, particularly in the early 2000s, when catches were much larger, the fishing levels may have been high enough to reduce kittiwake breeding success. Rising sea temperatures due to climate change also threaten sandeels, so kittiwake food supplies could be affected by both local and large-scale processes.
Dr Euan Dunn, the RSPB's Marine Policy Specialist: "Future management of the sandeel fishery needs to ensure that the intensity of exploitation on the Dogger Bank is sustainable. If our internationally important populations of seabirds are going to cope with climate change, then we need to make sure industrial fisheries are not adding to their problems.
"This is an example of why fisheries policy is vital to the health of our seas. As we leave the EU, we will need to replace EU policies with UK ones that protect our marine wildlife. We look forward to working with our new Secretary of State, Michael Gove, to help save the UK's seabirds, by ensuring that our Government continues to work with the other European countries that fish the North Sea after Brexit. Our thinking must be as joined up as the seas on which we all rely."
The paper 'Kittiwake breeding success in the southern North Sea correlates with prior sandeel fishing mortality' is published in Aquatic Conservation: Marine and Freshwater Ecosystems (http://onlinelibrary.wiley.com/doi/10.1002/aqc.2780/full)