Post release monitoring of rehabilitated gray seal pups over large temporal and spatial scales

Abstract

AbstractWildlife rescue and rehabilitation is used globally to aid the conservation and welfare of marine species, however, postrelease monitoring is challenging. Here, long‐term, regional postrelease monitoring provides feedback for rehabilitation centers for gray seals (Halichoerus grypus). Data from 1,094 rehabilitated gray seals over 19 years across the southwest UK were examined to assess postrelease survivorship and the impact of release site on movements and range. Using flipper tags combined with photo identification, 391 rehabilitated seals (35.7%) were resighted, including 188 seals (17.2%) that were traced back to a specific rehabilitated individual with release data. The maximum monitoring duration for a single rehabilitated seal was 17 years, although the majority (151/188; 80%) were sighted for less than 5 years and 80/188 (43%) were resighted for less than a year. Almost all 188 traced rehabilitated seals (n = 176, 93.6%) visited the St Ives Bay Wild Site, yet only half had been released at the adjacent St Ives Bay Release Site. Rehabilitated seals had similar dispersal patterns to their wild conspecifics but over a smaller area. Once released, rehabilitated animals face the same threats as their wild counterparts.