Introduction & Objectives

Harbor seals (Phoca vitulina) are one of the world’s most widely distributed pinniped species and are found in temperate to polar coastal waters of the northern hemisphere (Jefferson et al. 2015). Gray seals (Halichoerus grypus atlantica) are widely distributed over the continental shelf in cold temperate and sub-polar North Atlantic waters (Lesage and Hammill 2001). Both species are year-round coastal inhabitants in eastern Canada and New England and occur seasonally in the mid-Atlantic United States between September and May (Hayes et al. 2020). Individuals of both species move to northern areas for mating and pupping in the spring and summer and return to southerly areas in the fall and winter.

Since 2014, NAVFAC Atlantic has been conducting haul-out surveys in Virginia to determine habitat use, seasonality and abundance at several locations near Hampton Roads Navy installations and the offshore Virginia Capes operating area (Jones and Rees 2022). Surveys are highly dependent on weather, marine conditions, and survey crew availability. Due to these limitations, there is little flexibility to collect data where there is a paucity of information (e.g. sunrise/sunset and adverse weather conditions).

Camera traps have proved effective for monitoring wildlife in remote locations and with limited impact to the animals (Wearn and Glover-Kapfer 2019, Koivuniemi et al. 2016). In combination with the data previously collected at the known haul-out locations, camera monitoring is near continuous and will provide a more complete picture of the seasonal occupancy in Hampton Roads, which will allow us to detect or monitor changes to the local population over time.

Objectives for this study are to improve the understanding of local haul-out numbers and behavior to include any haul-out patterns in relation to environmental factors. Data collected will improve the assessment of potential impacts from Navy training and testing activities as required under the Marine Mammal Protection Act and National Environmental Policy Act for USFF and CNIC-funded projects in Hampton Roads Virginia.

Hayes S.A., Josephson E., Maze-Foley K., Rosel P.E. 2020. US Atlantic and Gulf of Mexico Marine Mammal Stock Assessments - 2019. NOAA Tech Memo NMFS-NE-264; 479 p.

Jefferson, T.A., Webber, M.A., and R.L. Pitman. 2015. Marine Mammals of the World: A Comprehensive Guide to Their Identification, Second Edition. Academic Press, San Diego, CA

Koivuniemi M, Auttila M, Niemi M, Levänen R, Kunnasranta M. Photo-ID as a tool for studying and monitoring the endangered Saimaa ringed seal. 2016. Endang Species Res. 30:29–36.

Lesage, V. and M. O. Hammill. 2001. The status of the Grey Seal, Halichoerus grypus, in the Northwest Atlantic. Canadian Field-Naturalist, 115(4): 653-662.

Wearn O., and Glover-Kapfer P. 2019. Snap happy: camera traps are and effective sampling tool when compared with alternative methods. R. Soc. open sci. 6:181748

Technical Approach

Eleven trail cameras are installed at eight different Virginia haul-out locations in two different survey areas 1) in the lower Chesapeake Bay at the Chesapeake Bay Bridge Tunnel (CBBT) islands, and 2) on the southern tip of the Eastern Shore.

Each camera records images throughout the local seal occupancy season from October through May.  Cameras are placed to provide maximum coverage of the known haul-out locations at the Eastern Shore area, and the two highest use areas of the CBBT. Images are recorded during daylight hours at a frequency of every 15 minutes.  The number of seals hauled out and in the water will be recorded for each image and these data will be compared to local environmental variables

Progress & Results

Remote trail cameras have been deployed at two sites in southeastern Virginia (on the Eastern Shore of Virginia & on the Chesapeake Bay Bridge Tunnel (CBBT) islands) for five complete field seasons as of May 2024. Seasons run from mid-October to late-May. Over 460,000 images have been collected from all five seasons. Photos are processed using Timelapse2 computer software. The review of the first four seasons of images is complete, and review of the fifth season (2023/2024) is in progress. The latest progress report (Guins et al., 2023) is available here. 

Seals have consistently been observed from October to late April/mid-May and are recorded in the highest numbers during the months of January and February. While the vast majority appear to be harbor seals, gray seals were positively identified in 94 different images across the first 4 seasons. Seals are observed hauling out in higher numbers at the Eastern Shore site versus the CBBT. Seals have been observed hauling out in higher numbers when tidal height was between 1 and 2 feet at the Eastern Shore and between -1 and 0 feet at the CBBT; at lower wind speeds; and at air temperatures around 49°F.

Statistical analyses are underway to further compare the effect of various environmental factors to the number of hauled out seals.

Below is the poster presented at the 2024 National Military Fish and Wildlife Association Annual Meeting in Grand Rapids, MI.