Kittiwake-up call on sandeel fisheries and climate change

Populations of the black-legged kittiwake will not recover unless the commercial sandeel fishery off the east coast of Scotland and north-east England remains closed indefinitely, ecologists have said. The stark warning comes from a paper published today in the British Ecological Society’s Journal of Applied Ecology. It is the first study to examine the combined effects of oceanography and fisheries on a North Sea seabird.

Kittiwake numbers in the North Sea have declined by more than 50% since 1990. According to Dr Morten Frederiksen and colleagues from the Centre for Ecology and Hydrology, the decline is due to both commercial sandeel fishing and climate change, which has resulted in warmer winters in recent years. “Reversing the trend towards warmer winters may be impossible and, at best, would be a very slow process. Therefore, to safeguard kittiwake populations we recommend that the current closure of the commercial sandeel fishery remain in place indefinitely,” Frederiksen says.

Kittiwakes in the North Sea feed almost exclusively on lesser sandeels, and sandeel numbers are reduced not only by commercial fishing, where they are used in fishmeal, but also by climate change because rising winter sea temperatures adversely affect the recruitment of young sandeels to the stock.

Using data on kittiwake numbers, breeding success and survival of adults, from 1986 to 2002, Frederiksen modelled the impact of changes in the sandeel fishery and in sea temperature on the kittiwake’s population. “Modelling indicated that the kittiwake population was unlikely to increase if the fishery was active or sea temperature increased, and that the population was almost certain to decrease if both occurred,” he says.

The European Union Fisheries Council banned sandeel fishing in the North Sea in 2000. The EU Fisheries Council is expected to confirm continued closure of the sandeel fishery through 2005 when it meets this month. Sandeels are a key resource for other marine predators, including seals, cod and most other seabirds, as well as the kittiwake.