This paper is based on a presentation at Plenary Session II of the Vancouver meetings of the Society: “Science and Marine Mammal Conservation”. Other papers from this Session will be published in future issues of Marine Mammal Science. Publication costs have been provided by grants to the Society from the National Marine Mammal Laboratory (NOAA/NMFS) and the Marine Mammal Commission. The convenor, G. Carleton Ray, also wishes to acknowledge Dr. Sheila S. Anderson of the Sea Mammal Research Unit, Cambridge, U.K., for her skillful chairing of the Session.
THE ASSESSMENT OF COMPETITION BETWEEN SEALS AND COMMERCIAL FISHERIES IN THE NORTH SEA AND THE ANTARCTIC1
Version of Record online: 26 AUG 2006
Marine Mammal Science
Volume 4, Issue 1, pages 13–33, January 1988
How to Cite
Harwood, J. and Croxall, J. P. (1988), THE ASSESSMENT OF COMPETITION BETWEEN SEALS AND COMMERCIAL FISHERIES IN THE NORTH SEA AND THE ANTARCTIC. Marine Mammal Science, 4: 13–33. doi: 10.1111/j.1748-7692.1988.tb00179.x
- Issue online: 26 AUG 2006
- Version of Record online: 26 AUG 2006
- Received: January 9, 1987 Accepted: September 2, 1987
- fisheries interactions;
- North Sea
Most of the exploited fish stocks in the North Sea are also used as a food supply by a number of seal species; the same is true for some fish and invertebrate stocks in the Antarctic—although the fisheries there are, at present, much smaller than those in the North Sea. The information needed for a critical assessment of such interactions is reviewed. Using existing techniques it is possible to estimate the quantity and size-classes of each fish or invertebrate species consumed by seals and to compare this with the commercial catch. If fishing mortality is known, these estimates can be used to calculate the level of mortality imposed by the seals. However, a realistic evaluation requires information on the distribution and movements of the fish, the seals' feeding effort, and the fisheries effort in time and space. At present it is difficult or impossible to obtain this information, but recent technological developments in telemetry equipment will soon make it feasible. To assess the economic effects of changes in seal numbers on the fishery, or the ecological effects of changes in fisheries effort on seal populations, requires additional information on the responses of the fishery and the seals to changes in fish abundance, and of the commercial market to changes in the supply of fish.