Winter is here in Virginia, and so are the seals!

Posted on January 21, 2025

NAVFAC LANT researchers are back at it for the 11^th field season of monitoring gray and harbor seals at two major haul-out locations in southeastern Virginia. The haul-out counts (which are conducted via vessel and drone), photo-identification, and camera trap monitoring are continuing for the 2024/2025 field season. So far, there have been 10 haul-out surveys completed since November 2024- 5 at the Chesapeake Bay Bridge Tunnel (CBBT), where seals have been recorded hauling out on the four rock armor islands, and 5 at a haul-out location on the barrier islands of Virginia’s Eastern Shore. With temperatures dropping these past couple of months, researchers have started to see an increase in the number of seals sighted during the surveys, with the highest counts of the season so far being 12 harbor seals at the CBBT site and 33 harbor seals at the Eastern Shore site.

In addition to the wildlife camera traps used to monitor the seals within the study area, a few infrared imaging cameras were added to the Eastern Shore site for the 2024/2025 season in order to monitor the nighttime haul-out activity of the seals. With these cameras, we aim to improve the estimation of time spent hauled out during the day versus at night, an important factor in assessing potential impacts from Navy training and testing activities as required under the Marine Mammal Protection Act. So far, we have observed upwards of 30 seals hauling out overnight on multiple different days. We are very excited to see what the results of this new monitoring effort will show us about the seals haul-out activity.

Image of seals hauled out at night captured by one of the infrared cameras deployed on the Eastern Shore of Virginia. Photo taken under NMFS GA Permit #25811.

Infrared cameras deployed at one of the major harbor seal haul-out sites on the Eastern Shore of Virginia. Photo taken by NAVFAC Atlantic under NMFS GA Permit #25811.

Seals can be identified as unique individuals by the marks and coloration of their pelage (or fur). Our photo-ID catalog of seals contains 4 individual gray seals and 198 individual harbor seals from the 2015-2023 seasons. To date, only one of the gray seals has been re-sighted within a different season at the Eastern Shore site. Of the 198 harbor seals, 96 (48 percent) were observed only once and 102 (52 percent) were re-sighted on more than one survey day across the eight field seasons. Some of the harbor seals in the catalog have been sighted across six and seven different field seasons!  An abundance estimate for harbor seals was calculated for the study area using mark-re-capture data from the photo-ID analysis. The estimated average abundance across eight seasons (2015–2023) was 150 individuals. These findings indicate that this region serves as an important resource for harbor seals by providing regular, seasonal haul-out sites for these animals within the lower Chesapeake Bay and Eastern Shore of Virginia.

Harbor seal, CB047, sighted at the Chesapeake Bay Bridge Tunnel across six different field seasons from 2016-2024. Photo taken by NAVFAC Atlantic under NMFS GA Permit #25811.

For more information on the Navy’s seal monitoring efforts in Virginia, see the project profiles for Haul-Out Counts and Photo-Identification of Pinnipeds in Virginia and Time-lapse Camera Surveys of Pinnipeds in Southeastern Virginia. All scientific activities are conducted under NMFS scientific research permit #25811.