A federal judge has denied a request from fishing groups that sought to challenge new fishing rules designed to protect rare whales.

The lobster fishing groups wanted a federal judge to stop regulators from placing new restrictions on the harvest of the crustaceans. The rules are intended to protect North Atlantic right whales, which number less than 340 and are vulnerable to entanglement in fishing gear.

U.S. District Court Judge James Boasberg denied the request in a Thursday ruling. It’s the latest in a string of legal setbacks for lobster fishermen who are coping with increasingly strict fishing rules meant to save the whales.

The Maine Lobstermen’s Association said in a statement that it was disappointed by the ruling, which it said “puts the future of Maine’s lobstering heritage at great risk, and along with it, the livelihoods of thousands of hard-working men and women.”

Conservation groups have long pushed for stricter protections for the vanishing whales. Kristen Monsell, oceans legal director at the Center for Biological Diversity, said in a statement the ruling affirms “right whales can’t wait any longer for stronger protections from deadly entanglements in fishing gear.”