The National Marine Fisheries Service (NMFS), the U.S. government agency that regulates offshore fishing, is proposing a complicated plan to reduce the number of Atlantic bluefin tuna that long-line fishermen inadvertently snare while trying to hook yellowfin tuna, swordfish and big-eye tuna. The fish has been intensively managed for more than two decades, but officials said the regulations need updating, in part to help reduce bycatch.

Under the proposal, the NMFS would sharply cut back on the number of bluefin tuna that individual fishing vessels are allowed to capture accidentally, setting a quota for each boat and requiring fishermen to include the bluefin they discard at sea under that cap. The NMFS also would change the formula for the weight of bluefin tuna that a long-liner may legally bring to shore for sale. Cameras and human observers on the boats would monitor compliance.