Grey seal records in Delaware come almost entirely from the mouth of Delaware Bay, the open shoreline and Cape Henlopen State Park where the bay narrows into the Atlantic. That’s the kind of exposed, sandy edge a seal needs to haul out and rest between trips to feed, and it’s a narrower slice of coastline than the animal’s full mid-Atlantic winter range.
A cold-water hunter passing through
Grey seals are among the larger seals that show up along the mid-Atlantic coast, built with a thick blubber layer for cold water and a diet centered on flounder and other bottom-dwelling fish. They don’t breed or raise pups in Delaware. Their pupping grounds sit farther north, off New England and Atlantic Canada, so the seals recorded here are typically resting or foraging animals passing through on a longer seasonal range.
A hard winter cutoff in the records
Records are heavily loaded into January through March and effectively disappear from April through November. That’s a seasonal pattern, not a sign the seals leave for good. Grey seals move south along the coast as northern waters cool and head back north again as spring arrives, and Delaware’s records track that movement closely.
Status in Delaware
NatureServe doesn’t assign Delaware a numeric rank for the grey seal, reflecting its status as a seasonal visitor rather than a species that breeds and raises pups here. It isn’t listed as nonindigenous by USGS NAS and is treated as native to the waters it uses.
