Grey seal, Halichoerus grypus, habitat selection around haulout sites in the Baltic Sea: bathymetry or central-place foraging?

We investigated habitat selection by grey seals, Halichoerus grypus, around haulouts in the Baltic Sea. Home ranges (95% fixed kernel) varied in size from 1088 to 6400 km(2). Observed habitat use was tested against the circul ar home range predicted from a simple central-place model. The overlap betw een the home ranges predicted by this simple model and actually exhibited b y the seals was < 70% for 9 of 11 seals. Furthermore, the depth distributio ns of the utilised areas were significantly different from that available i n the circular home range for all 11 seals. Seals selected depths of 11-40 m and avoided areas > 51 m deep. Ten of the 11 seals used areas within a 50 -km radius around the haulout site for more than 75% of the time. Thus, in spite of their mobility and the availability of many islands, seals usually remained in the vicinity of a specific haulout site for extended periods. The seals did not use the habitat around the haulout site as predicted by t he simple central-place model, but selected habitat according to bathymetri c characteristics (e.g., water depth). Detection of these relatively small but heavily used home ranges around haulout sites may be of assistance in m anagement plans in order to reduce the growing number of seal-fisheries con flicts.