A federal judge has ruled that two fishing areas off New England will remain closed to certain kinds of gear to protect an endangered species of whale.

The case was between the environmental group Conservation Law Foundation and the federal government. Judge James Boasberg of the U.S. District Court for the District of Columbia ruled the government is forbidden from allowing gillnet fishing in the two areas off Nantucket until it has fully complied with the Endangered Species Act and other federal protection laws.

Gillnets are large nets designed to catch many fish at once, and they also present a risk of harming marine mammals such as the North Atlantic right whale. The government moved to reopen some 3,000 square miles of ocean to the gear last year in a move that earned condemnation from environmentalists.

There are about 400 right whales left.

“This ruling rightfully reverses a dangerous course and will give right whales the protection they need from fishing gear,” Conservation Law Foundation attorney Erica Fuller said.

The National Oceanic and Atmospheric Administration’s National Marine Fisheries Service is not commenting on the ruling, spokeswoman Jennifer Goebel said Tuesday.

The fisheries service argued during the court case that gillnets don’t pose a greater threat to whales than other types of vertical fishing lines. But in his ruling in favor of the environmentalists, Boasberg wrote the agency didn’t deny “the conclusion that opening these two areas to gillnet fishing will irreparably injure North Atlantic right whales.”

The right whales, which travel through heavily fished New England water bodies such as the Gulf of Maine and Georges Bank, are a focus of conservation groups because their population has fallen in recent years. The federal government is also in the midst of developing a protection plan for the whales that could place new restrictions on New England’s lobster fishery.