Diet and breeding performance of black-legged kittiwakes Rissa tridactyla at a North Sea colony

It is also the target of the largest single species fishery in the North Sea with annual catches of between 0.7 and 1.1 million t over the last 10 yr (Gislason & Kirkegaard 1998, ICES 2001). The size of this industrial fishery, coupled with the importance of sandeels to marine predators, has led to concern over the potential impact of sandeel harvesting on the North Sea ecosystem and speculation that the fishery and birds might be competing for the same resource (Monaghan 1992).