The NEFSC has been conducting aerial surveys of gray seal pupping colonies since 2005 to monitor the number of pups born in U.S. waters. Surveys are flown from either a Cessna 252, Cessna Skymaster, or NOAA Twin Otter at altitudes ranging from 180-230 meters, using hand-held or belly-mounted Canon camera systems. Surveys may also be conducted with Uncrewed Aircraft Systems (UAS) at select colonies. Ideally, surveys are flown after all pups are born and before they start leaving the colony, but in some years surveys may have been flown before or after this optimal window. Furthermore, not all colonies may have been surveyed each year due to logistics or if the site was not yet an established pupping colony. The Northeast Fisheries Science Center has been conducting aerial surveys of harbor seals since 1983 to monitor the abundance of the population in U.S. waters. Surveys are flown during the pupping season when animals are concentrated on the coast of Maine and timed to coincide with peak pupping estimated to be around the end of May. Surveys are flown from a NOAA Twin Otter at 230 meters within 2 hours of low tide using a hand-held Canon camera and fixed 300mm lens. Close to 1,000 ledges are surveyed and grouped into bay units for analysis.