Scientists from the Center for Coastal Studies Right Whale Ecology Program observed two endangered North Atlantic right whales in Cape Cod Bay during an aerial survey Monday, Nov. 18. It was the first such sighting of the 2024-2025 field season.
One whale was located less than a mile east of Pilgrim Beach in Plymouth, while the other was sighted on the other side of Cape Cod Bay, 7 miles west of Wellfleet. After collecting photo identification, the aerial observers notified the team aboard the CCS research vessel Shearwater, so they could sample the zooplankton patch upon which the whale off Pilgrim Beach was feeding.
The whales were identified as two juvenile males; a 4-year-old and a 3-year-old which has been observed in Cape Cod Bay every year for the last three years, including as recently as April 2024.
The 3-year-old was observed skim feeding, or feeding on zooplankton near the surface of the water. Such behavior is usually not observed until much later in the season.
"It is normal to have right whales popping in and out of the bay throughout the year. However, it is surprising to see skim feeding in the fall," CCS researcher Christy Hudak said.
Based on the samples collected in the path of the skim-feeding right whale, the zooplankton patch contained a combination of the whales' three favorite copepods or microscopic crustaceans, including the oil-rich Calanus finmarchicus.
"Although Calanus was not the dominant species in the sample, its presence in higher numbers is unusual for this time of year and it will be exciting to see if the food resource this year will prove a banner season for right whales in Cape Cod Bay," Hudak said.
North Atlantic right whales are a critically endangered species, with a total population estimated at just 372, only 70 of whom are breeding females.
They typically arrive in Cape Cod Bay in early winter with many staying into mid-May.
Last year, nearly half the North Atlantic right whale population was observed in Cape Cod Bay, whose protected waters provide an important source of the zooplankton on which they feed.
Currently, seasonal protections for North Atlantic right whales are not yet in place, so boaters should be aware that there are whales in the area and exercise caution.
State regulations that include prohibiting the setting of fixed fishing gear and limiting the speed of vessels to 10 knots go into effect early next year, when right whales arrive in larger numbers in Cape Cod Bay. Ship strikes and entanglement are the leading cause of right whale deaths.
During last week's survey, CCS aerial observers also sighted seven Risso's dolphins. Risso's dolphins are usually found in deep, open-ocean waters, which makes sighting them in the relatively shallow waters of Cape Cod Bay an infrequent occurrence.
"We were happy to see all of those animals free-swimming, as they are known to strand when found in Cape Cod Bay," CCS researcher Ryan Schosberg said.
The Center for Coastal Studies in Provincetown is a nonprofit organization dedicated to understanding, preserving and protecting marine ecosystems and the coastal environment through applied research, education and public policy initiatives.