Federal officials trying to institute new regulations on Maine’s lobster fishing industry exceeded their authority and focused on “worst case scenarios” when creating new rules, according to a new federal filing.

The Maine Lobstermen’s Association on Thursday filed its opening brief with the U.S. Court of Appeals as the industry works to beat back regulations that it says will crush Maine’s signature fishery.

Federal officials have proposed gear modifications to reduce the incidence of entanglement for endangered right whales, which number about 340. Other regulations would close certain areas to lobster fishing while the whales are migrating.

The last documented entanglement in Maine lobster gear was in 2004, and no whale deaths have been attributed to the industry.

The lobstermen’s association argues that the National Marine Fisheries Service must prove Congress gave it authority to issue stringent rules.

“NFMS simply assumed on the front end of the process that economically debilitating conservation restrictions on the lobster fishery are necessary and then generated a biological opinion that did nothing but confirm that those extreme restrictions — untested for reasonableness or prudence — would not jeopardize the right whale,” the filing reads.

Attorneys for the lobstermen also argue that the Endangered Species Act requires federal agencies to rely on “best available data, not the most improbable scenarios.”

“The agency error here is glaring,” the brief reads. “After all, NMFS concededly never focused on what would ‘likely’ occur to the right whale if it continued to authorize the American lobster fishery.”

The federal government has until Dec. 20 to file its response in the case.

In October, hundreds of lobstermen and their supporters packed a meeting in Portland to explain to federal regulators how the changes would hurt their industry. 

A month earlier, the industry and Maine politicians began fighting back against a designation by Seafood Watch that warns consumers against buying Maine lobster, saying the industry isn’t doing enough to protect right whales.