Tamanend’s bottlenose dolphin records in Delaware cluster right where Delaware Bay opens into the Atlantic, Cape Henlopen State Park, the open Delaware Bay shoreline, and Delaware Seashore State Park just to the south. That’s exactly the kind of water this coastal dolphin favors, the mix of estuary mouth and nearshore continental-shelf water where a bay transitions into open ocean.
A bay-and-shore dolphin, recently given its own name
This is the coastal group long lumped in with the common bottlenose dolphin before researchers split it into its own species. It sticks to bays, estuaries, sounds, and nearshore water rather than venturing far offshore, feeding mainly on fish and sometimes working together to herd prey into shallow water. Calves stay close to their mothers for several years, long enough to learn the local feeding grounds and travel routes their mothers use.
A sharp warm-season pattern in the records
Records are close to zero from November through February and build fast from March onward, peaking in July and August before tapering off in the fall. That pattern lines up with the species moving into Delaware’s bay and nearshore waters as they warm each year and shifting south again as the water cools, a seasonal pattern the records make visible even though they can’t say how many dolphins make the trip.
Status in Delaware
The dolphin’s recent split from the common bottlenose dolphin means its conservation status hasn’t been formally assessed yet. It isn’t listed as nonindigenous by USGS NAS and is treated as native to the Delaware Bay and coastal waters it uses.
