Maine lobstermen have been swapping out gear for years and limiting fishing to certain areas to avoid entanglements with North Atlantic right whales. With new rules in the works, the state’s congressional lawmakers are pushing back, saying Maine lobstermen would be hit harder than their competition across the borders.

Under a federal mandate meant to reduce the accidental killing, or “take,” of right whales, Maine’s Department of Marine Resources has until September to submit a plan to reduce lobster buoy lines by 50 percent. Maine’s representatives in Washington, D.C., believe differences in how plans are drafted in other states and a lack of similar rules in Canada would put Maine lobstermen at a disadvantage.

Protecting the right whale habitat has been a moving target, literally. The whales have been moving north following their food supply — fatty rice-sized crustaceans called Calanus finmarchicus — as they migrate away from warming waters in the Gulf of Maine.

Some deep waters in the Gulf of Maine have warmed 9 degrees since 2004, according to a study published in June by scientists from 10 institutions, including Bigelow Laboratory for Ocean Sciences in East Boothbay. Additionally, the study found that climate change has shifted circulation patterns, causing right whales to pop up in unpredictable places.

“For decades, we have known where and when to find right whales,” Dan Pendleton, a research scientist at the New England Aquarium, said. “Now the paradigm is breaking down, and we’re seeing changes to behaviors that had remained consistent since before people started observing them.”

Historically, right whales have traveled to the Bay of Fundy in the fall. But as Calanus have become less abundant there, the whales have followed their food source out of areas designated to protect them, leaving them vulnerable to getting snagged in fishing gear.

In a May 28 letter to Dr. Neil Jacobs, acting undersecretary of commerce for oceans and atmosphere at NOAA, all four members of the Maine delegation — Sens. Susan Collins and Angus King, and Reps. Chellie Pingree and Jared Golden — questioned NOAA’s methodology, called the guidelines unfair to Maine lobstermen and asked that the industry be consulted in the decision-making process.

“While lobstermen and regulators in Maine have put forward a plan to reduce the fleet’s vertical lines by 50 percent, other states and lobster fishing areas have not done the same,” the letter read.

Maine’s representatives said NOAA’s methodology assumes the same risks in U.S. and Canadian waters, but that is not the case: “The risk reduction target and management measure used to reduce risk to whales should more accurately reflect the proportion of entanglements seen in the data related to each country.”

Additionally, they asked that a “decision support tool” used to help calculate the severity of risk posed to whales by different types of fishing gear be put through a peer review process.