COMPARATIVE DISTRIBUTION, MOVEMENTS AND DIET OF HARBOR AND GREY SEALSFROM THE MORAY FIRTH, NE SCOTLAND

1. The distribution, movements and foraging activity of harbour and gr ey seals from the inner Moray Firth, N.E. Scotland, were compared usin g a combination of observations at haul-out sites, VHF and satellite-l ink telemetry, and analyses of diet composition. 2. Terrestrial abunda nce of both grey and harbour seals was highest during the summer but t here were marked differences in the extent to which the two species mo ved between different haul-out sites. Harbour seals showed local seaso nal changes in distribution, but all 21 radio-tagged seals moved only to alternative haul-out sites within a range of 75 km. In contrast, fo ur of the five grey seals tracked from the Moray Firth moved to haul-o ut sites 125-365 km away, and provided evidence of interchange between the Moray Firth and other grey seal breeding areas in Orkney, the Fir th of Forth and the Farne Islands. 3. All harbour seals foraged within 60 km of their haul-out sites, but showed seasonal variation in their foraging areas which was related to changes in their terrestrial dist ribution. In contrast, those grey seals which foraged within the Moray Firth travelled up to 145 km from haul-out sites. Nevertheless, there was some overlap in the foraging areas used by harbour seals and grey seals in more inshore areas. 4. Sandeels, gadoids, flatfish and cepha lopods formed over 95% of the diet of both species. However, dietary d ata, particularly for grey seals, may be biased toward those individua ls which fed in more inshore areas. 5. These results suggest that Mora y Firth harbour seals can be considered as a relatively discrete popul ation, with clear links between breeding, feeding and resting areas, a nd little exchange of adults between this and adjacent breeding areas in Orkney and the Tay Estuary. In contrast, grey seals from several di fferent breeding sites appear to move into the Moray Firth in summer a nd use the area primarily for foraging and non-breeding haul-out.