Anglers who regularly fish the waters off the Northwestern Hawaiian Islands for migratory fish like bigeye and yellowfin tuna say the proposed boundaries of a national monument there could be slightly altered to make a more effective marine preserve — and also let them keep fishing.

Fisherman Joe Dettling, who sails out of Honolulu Harbor, said pelagic or deep-sea handline fishing has no significant impact on the marine life of the islands and reefs of the monument, and he has the agreement of Bill Robinson, head of the Pacific Islands Regional Office for the NOAA Fisheries.

"It's hard to make a scientific argument that fishing for pelagics has any measurable effect on the ecosystem at all," Robinson said.

Sean Corson, field operations coordinator for the Northwestern Hawaiian Islands Marine National Monument, said, "People would be hard-pressed to say what the effects are, up and down the food chain."

Eight boats with permits for bottomfishing from NOAA will be allowed to continue fishing in the monument for five years. They will also be allowed to catch up to 180,000 pounds annually of pelagic fish. But the several Hawai'i anglers who fished legally for pelagic fish in the region have been entirely cut out, and they're arguing that it's not fair to them or to Hawai'i fish consumers.

When the boundaries of the monument were drawn, they generally followed the boundaries previously established for the proposed national marine sanctuary in the area. The boundaries of the monument generally run 50 miles out from the 10 islands and reefs that form the Northwestern Hawaiian Islands, a vast area covering nearly 140,000 square miles.

As drawn, the monument's borders cut out two of the most productive pelagic fishing areas in the region — both more than 30 miles from the nearest island.

The boundary cuts through the Northhampton Seamount, a favored area for pelagics. The seamount lies 44 to 60 miles from Maro Reef. The other key fishing area is around NOAA's weather station, Buoy 51001, locally called Buoy One, which is anchored 34 miles north of Nihoa island.

"At Buoy One, we had a two-month period when we caught half a million pounds of fish there," Dettling said.

Fellow deep-sea fisherman Robert Cabos, who fishes out of Hilo, Hawai'i, said that when fish prices are low, it does not make economic sense to go the hundreds of miles to these fishing spots. But when fish are in low supply and prices are good, they can be an important resource.

"We get good-eating, fat fish up there, and we want to kind of protect our future. Buoy One goes off really good some years with bigeye and yellowfin (tuna), and that can be very important," Cabos said.

There is, he said, another key reason for keeping Hawai'i-based anglers in the area: It's unlikely the monument will ever have enough money to provide extensive enforcement of its no-fishing zones, but committed local boaters can help provide a level of security.

"We're the best protection, being up there. We know who belongs up there and who doesn't, and we call it in," Cabos said.

The Western Pacific Regional Fishery Management Council has asked NOAA to consider moving Buoy One north, out of the monument area, but no decision has been made about that.

The fishermen don't want to shrink the monument, and in fact they said it should be expanded to the south to better protect shallow reef areas. Dettling said that for the maximum effectiveness, the government might consider moving the boundaries farther from shore in the area from Necker or Mokumanama to Gardner Pinnacles. Those regions have extensive banks to the south, which are used by monk seals for feeding, Dettling said.

He said that he and Cabos are considering legal action to adjust monument boundaries.

"I know nobody really objects to us. If they could just adjust these lines, it would take some pain out of fishermen's lives," Dettling said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.