Date of Award

Summer 8-22-2020

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Kristina Cammen

Second Committee Member

Damian Brady

Third Committee Member

Sean Todd

Abstract

Over the past several decades, the Gulf of Maine (GOM) has experienced significant socio-ecological change. Extreme climatic variation increases in human population, and visitation of coastal areas have significantly impacted coastal ocean health and redefined multispecies ecologies. While pinniped populations in the Northeast United States have generally grown following federal protection, they have also experienced multiple mortality events over the past two decades. Long-term datasets from marine mammal stranding networks represent a valuable resource for investigating trends in marine mammal health during this period of change. Here, I evaluated potential drivers of marine mammal strandings using data collected from stranded harbor (Phoca vitulina), harp (Pagophilus groenlandicus) and gray (Halichoerus grypus) seals from 2002 to 2017 in Massachusetts, New Hampshire and Maine. I tested for spatio-temporal correlations between stranding density and potential social (e.g., population density) and environmental (e.g., sea surface temperature, North Atlantic Oscillation, snowfall and sea ice extent) factors. Our models reveal significant effects of location and human population density on stranding rates across species—signifying that, even after correcting for reporting effort, pinnipeds are more likely to strand near more densely populated human epicenters in the GOM—as well as speciesspecific relationships with some environmental factors. These analyses increase our understanding of the circumstances that lead pinnipeds to strand in the Gulf of Maine and provide context within which these species may serve as sentinels of coastal ocean health.

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