NEW ORLEANS — Boats using surface fishing lines with miles of baited hooks would get individual yearly limits for bluefin tuna bycatch under rules proposed to end the practice of dumping dead bluefin caught on hooks meant for other species.

Bluefin tuna, which can weigh 500 pounds and sell for thousands of dollars — the record is $736,000 — have been severely overfished to feed a worldwide market for sushi.

Groups specifically fishing for bluefin, from anglers to general fishing boats, would lose nearly 69 tons of their current total quotas — or about 7 percent of the total U.S. quota for Atlantic bluefin — to create the new longline quotas proposed by the National Oceanic and Atmospheric Administration’s fisheries division.

But once a longline boat reached its quota it would have to stop using the lines, which can extend up to 20 miles and carry thousands of hooks.

“The longliners will be held to a very strict threshold,” said Bradley S. McHale, a fishery management specialist with NOAA Fisheries.

The rules made public Tuesday would also bar surface longlines from part of the Gulf of Mexico during April and May, the peak of spawning season. In an area off Cape Hatteras, N.C., they could be used from December through March only by boats that have proven able to use the gear without catching bluefin.

The proposals are generally “a step in the right direction, toward ending the waste of this depleted fish,” said Tom Wheatley, who manages the Gulf of Mexico surface longline campaign for the Pew Charitable Trusts. The individual quotas would “introduce a level of personal responsibility we’ve never seen before in the longline community,” he said. He has pushed for a six-month ban in a larger area of the Gulf.

Longline boats fishing for other species — such as swordfish, wahoo, and bigeye, yellowfin or albacore tuna — may now keep one to three bluefin for every 2,000 to 30,000 pounds of the species they’re licensed for, McHale said. Others get thrown back. So do any caught once the entire longline fleet has reached its quota.

The new rules would require longliners to account for every bluefin they catch, including those too small to keep. Quotas could be leased by below-quota boats to boats that went over.

McHale said only 18 of the 161 boats that use surface longlines off Cape Hatteras would be kept from using them in the proposed restricted area during winter and early spring — and they could use other gear, just not longlines.

NOAA Fisheries has scheduled 10 hearings from Maine to Texas to get public comment on the proposals, which take 56,000 words — enough for a novel — in Wednesday’s Federal Register.

Bluefin behavior and migration paths are so complex that the rules may not be as effective as regulators hope, said Molly Lutcavage, a University of Massachusetts scientist who studies bluefin.

“I think they missed the root problem — that is, we lack adequate scientific understanding to really manage this species efficiently and intelligently,” she said.

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