PORTLAND, Maine (AP) — Interstate regulators could be about to tighten the restrictions on the last species of shark that can have their fins removed at sea in the U.S.

Smooth dogfish are the only sharks from which American fishermen can remove fins at sea. Many other sharks can be hunted, but fins can’t be removed until processing on land.

The Atlantic States Marine Fisheries Commission is scheduled to vote on Tuesday on a new rule that would allow fishermen to bring smooth dogfish to land with fins removed as long as their total retained catch is at least 25 percent smooth dogfish. Right now they can bring ashore as many as they choose.

The fins are used to make shark fin soup. Environmentalists want to shut the U.S. shark fin market down completely.