In this March 28, 2018, file photo, a North Atlantic right whale surfaces in Cape Cod bay off the coast of Plymouth, Mass. Credit: Michael Dwyer / BDN

For the first time in four decades, marine scientists were unable to find any North Atlantic right whales in the Bay of Fundy this year.

“Always we would have a handful, even in recent years. So to have zero is certainly disturbing or frustrating,” said Amy Knowlton, a New England Aquarium whale researcher who has been tracking the endangered species from a base in Lubec every year since the early 1980s.

She said that for decades, anywhere from 50 to 150 right whales showed up in the summer and fall to forage. The numbers started to drop off around 2010, as water temperatures in the Bay and Gulf of Maine began to rise at a rapid clip.

“It’s just a reflection of how the ocean is changing with climate change, and their food resource, plankton, they’re not blooming at the same time and in the same areas that they used to, so it’s a reflection that for them and for our oceans things are changing pretty dramatically,” Knowlton said.

She said that while the right whales may be foraging elsewhere for the moment — including off Cape Cod and in the Gulf of St. Lawrence — they could return to the Bay of Fundy in future years. And she said climate change is also bringing formerly rare species to the Bay, including humpback whales and loggerhead turtles.

Meanwhile, a right whale was seen off the coast of New Jersey this week, badly entangled in fishing gear. Conservationists, scientists, lobstermen and the federal government are in a contentious dispute over the best way to protect the species.

After several delays, federal regulators are expected to propose new rules for fishing gear as soon as this month.

There are fewer than 400 right whales believed to be left on the planet.

Clarification: New England Aquarium researchers based in Lubec did not observe any right whales this season, but the aquarium says it was able to confirm that citizen scientists took photos of two juvenile whales swimming in or near the Bay of Fundy.