Identifying important marine areas for pinnipeds : a comparison of approaches

Abstract

Given the widespread decline of species and threats to habitats across the globe, identifying important areas for conservation is now more important than ever. With ever-improving technology, the use of tracking data has recently contributed valuable information on the movement of marine organisms, and has allowed for insight into habits and habitat use of animals such as pinnipeds that are difficult to study. For example, Important Bird and Biodiversity Areas (IBAs) have been identified using seabird tracking data (BirdLife International (BI) approach). In this study the applicability of the BI approach to pinniped data was tested, based on similarities in foraging patterns and attendance cycles between seabirds and female pinnipeds during their breeding season. PTT and GPS data from nine species were analysed using the BI approach and compared to three commonly used methods of spatial analysis; Kernel Density Estimation, Minimum Convex Polygon, and Time-spent-in-Area analyses. The 50% home range was used to analyse the size of areas and the percentage overlap between areas identified by different methods. The BI approach and other methods were all able to effectively identify important areas for ten of eleven data groups, though the areas identified by all four methods differed in their extent and exact location. Advantages and disadvantages of each method should be taken into account in conservation management though this study indicates that the BI approach is a good compromise between these. Future developments could include broadening of the approach to incorporate a wider range of pinniped species.