Seals use haul out locations to rest, give birth, molt and nurse pups and they rely on the ocean for their food. Therefore, they are affected by degradation of both marine and terrestrial habitats. As top predators, they bioaccumulate persistent organic chemicals that flow from land to sea. A near-shore species, harbor seals live close to human activity and are subject to human disturbance such as pollution, coastal development, fisheries and recreational boating. As a species with wide spatial distributions and long lives, they reflect long-term ecosystem trends and are excellent subjects for long-term monitoring programs.
The harbor seal population in New England waters is currently estimated at approximately 99,300 seals. Blue Hill Bay and Penobscot Bay contain the greatest abundance of seals on the Maine coast during the May – June pupping season. Surveys from 1981 to 2001 show that harbor seal pups are consistently most abundant in Blue Hill Bay. Approximately 27% of all pups surveyed in 2001 were born in Blue Hill Bay, thus this area is considered a critical pupping habitat for the for the entire Northeast population of harbor seals.
In conjunction with the Institute’s ongoing Seals as Sentinels research, we are conducting a fine-scale, regional Pinniped Monitoring Program using harbor seals in the greater Blue Hill Bay area as local indicators of population-level health. Institute researchers conduct aerial, vessel, and onshore surveys of the area seal population on a monthly basis from May to October while they also collect data on various environmental parameters.
The study examines the abundance and distribution of harbor seals, number of pups, proximity to local contaminant sources and seasonal haul out site usage. We also monitor for the presence of gray seals in the area. Over time, the monitoring effort will provide valuable background information for the Seals as Sentinels project and help elucidate factors affecting the health of the population. The program will also provide baseline ecological and spatial data to be shared with marine mammal researchers and resource managers.
The long-term goals of this program are to determine harbor and gray seal distribution in the region, to understand the dynamic nature of their habitat use, and provide insight into the potential impacts of ocean pollution, climate change, habitat destruction, and disease in our seal populations. This data will be compared with data collected by NOAA and other researchers to provide insight into trends in harbor and gray seal abundance in the mid-coast region. Ultimately, the data can help inform decisions regarding the future conservation of Maine’s pinniped species.