State environmental officials this week issued a “high risk” warning to boat operators asking them to stay alert after five North Atlantic right whale mother and calf pairs were spotted foraging on plankton in Cape Cod Bay.
According to the advisory from the Massachusetts Division of Marine Fisheries, the highly endangered whales were seen feeding Thursday in the western part of the bay during an aerial survey conducted by researchers from the Center for Coastal Studies.
Marine Fisheries officials reissued the warning to boat operators on Sunday, fearing that a close encounter could lead to someone accidentally striking the whales.
“Given their behavior and the proximity to vessel traffic, the situation presents a high risk of vessel collision to a sensitive and important segment of the right whale population,” according to a statement.
It’s against state and federal law for boats to come within 500 yards of North Atlantic right whales. The whales are one of the most endangered ocean species. Only 526 are alive in the world, according to the Center for Coastal Studies.
The whales were swimming roughly 2 miles from the shoreline, between Plymouth and Sandwich, officials said. The mother whales were “subsurface feeding on dense patches of zooplankton” with the calves swimming nearby, they said.
Because feeding conditions are favorable for the whales, and they could remain in the area for a few days, officials have urged boat operators to proceed with caution, reduce speeds to less than 10 knots, and post lookouts for other operators to help avoid collisions.
“Vessels that find themselves within 500 yards of a right whale should slowly and cautiously exit the area,” state marine fisheries officials said.
Researchers from the Center for Coastal Studies, in Provincetown, announced in February the official start of the right whale season, when the animals become more abundant in Massachusetts waters.
Earlier this year, the National Oceanic and Atmospheric Administration announced plans to expand the “critical habitat” of the whales, which feed and congregate in Cape Cod Bay and the Gulf of Maine up to Canada.