2011 and 2012 Harbor Seal Tagging and Abundance Estimation Project
From March to May of 2011, and again during the same period in 2012, researchers from the Northeast Fisheries Science Center and several other institutions conducted harbor seal (Phoca vitulina) live capture, tagging, and biological sampling operations. The primary purpose of the project was to attach radio tags to the seals to obtain a correction factor that would estimate the number of seals not hauled-out (therefore not available to be observed/counted) during the aerial abundance surveys to be flown during peak pupping in late May along the coast of Maine. This correction factor was to be applied to the raw seal counts obtained from the aerial surveys in order to estimate the total harbor seal population size. Secondary objectives were to study short-term movements and collect health assessment and stock identification samples. Collaborating institutions included the Woods Hole Oceanographic Institution, International Fund for Animal Welfare, Riverhead Foundation for Marine Research and Preservation, Provincetown Center for Coastal Studies, University of Maine, Maine Department of Marine Resources, NOAA Northeast Regional Office, New England Aquarium, Marine Mammals of Maine, and the University of New England Marine Animal Rehabilitation Center. Support for the project was provided by the AMAPPS program.
The first phase took place in Chatham and Wellfleet, MA. Seals were captured using a 500 foot long gillnet. Once live captured, each seal was measured and weighed, biological samples (e.g., blood, skin, hair, morphometrics) were collected, and the seal was outfitted with both a flipper tag for identification and a small VHF radio tag before being released.
Phase two took place in Rockland, Maine, where more seals were captured and tagged. During this phase of the project, the Riverhead Foundation contributed expertise and satellite tags which provided additional information on movement patterns and habitat use of two seals captured near Rockland.
Aerial work was hampered by poor weather in May 2011, which was the reason the captures were repeated in 2012. The 2012 aerial survey was successful and researchers were not only able to do the photography required to obtain the raw count, but also to obtain the tag retrieval information necessary for calculating the correction factor.
For more information, see the NEFSC press release on this project.
All seal capturing, handling and sampling were performed under MMPA research permit 775-1875 and Department of the Interior, Cape Cod National Seashore Special Use Permit #CACO-2011SCI-0001.
Working up a seal on the beach. Photo: Michael Moore, WHOI
Satellite-tagged seal being released. Photo: NEFSC
Harbor seals on the islands off Rockland, Maine. Photo: NEFSC