Non-invasive genetic tracking of Harbor Seals (Phoca vitulina)

Understanding the effect of individual differences on trophic interactions of upper-level predators, which can have disproportionate effects on an ecosystem, is imperative for successful management of populations. Marine mammals that prey on fish species of commercial and conservation importance are thus of particular interest. However, quantitatively monitoring and evaluating the impact of marine mammals on the environment is challenging because it is difficult to observe, capture, and collect repeated samples of individuals. Molecular genetic analysis of scat provides an inexpensive and feasible option to address these challenges. I developed an innovative non-invasive method for re-sampling individual marine mammals by collecting harbor seal (Phoca vitulina) scat at a haul-out in Cowichan Bay, B.C. I chose to study this species because it is the most abundant pinniped in the inland waters of the Pacific Northwest and a notable predator on fisheries stocks. In addition, a Python-based computer program for experimental design, incorporating genotyping error, was created to determine the sampling schemes needed to genetically track individuals of any taxa with site fidelity. My results demonstrate that non-invasive individual tracking via microsatellites can be successfully implemented in marine mammals. Furthermore, the optimum sampling scheme to track individuals over a given time frame at the study site requires 690 samples over 23 bouts (30 samples per bout). These genetic-tracking and sampling scheme methodologies can be applied to help answer several biological questions including diet, relatedness, population structure and impacts on species of interest