Longline fishing boat owners said they expect to lose millions of dollars in tuna catches in the central and western Pacific under an agreement in which the United States will reduce its longline tuna catch for three years starting in 2015.

The 27-member Western and Central Pacific Fisheries Commission, a multinational group formed to promote a sustainable fishing stock in the Pacific, approved the agreement in December in Cairns, Australia.

Once the agreement takes effect, U.S. longline fishing boats in the western and central Pacific face a 10 percent reduction in their quota of bigeye tuna — amounting to at least a $10 million loss in bigeye tuna sales by 2017, fishing industry officials said.

About 89 percent of the total U.S. longline catch of bigeye tuna is caught by Hawaii boats. Observers said the 89 percent represents around 5 percent of the total bigeye longline catch in the western and central Pacific Ocean.

In addition, U.S. purse seine fleets will likely be losing tens of millions of dollars because of reduced tuna catches in the western and central Pacific as a result of the agreement.

Longline boats will be forced to try to make up for their reduced quota by traveling to the eastern Pacific on trips that take one to three days longer and are more costly.

Hawaii Longline Association President Sean Martin, who was part of the U.S. delegation at Cairns, said he was disappointed with the commission’s decision.

MARTIN said the commission is conducting an assessment of the bigeye tuna fishery this year, and the results are expected to be presented at its annual meeting in December.

Fishing industry officials said while the U.S. has complied with ongoing conservation and management measures set forth by the commission through strict monitoring and enforcement agreements, a number of other nations — including China and South Korea — either exceed quotas or do not monitor catches to the same level as the U.S.

Martin said in 2008 the commission set a limit of 204 for the number of purse seine vessels in the Western Pacific, but there are now more than 300. The U.S., he said, has kept its number of vessels to the 40 as agreed to in the 2008 measure.

"In addition, Hawaii’s longline fleet fish is thousands of miles away from where 90 percent of the bigeye fishing mortality occurs, which also makes us unique in terms of our impact on the stock," Martin said.

Brian Holman, chief executive officer of the American Tuna Boat Association, based in San Diego, said the commission’s decision bolsters the economy of small island nations but doesn’t reduce the amount of tuna caught in the region.

"It’s an economic decision," Holman said. "It wasn’t based on conservation reasons."

Holman said U.S. purse seine fishing boats operating mainly in the American Samoa region face a loss of 800 to 1,000 fishing days — or about $50 million annually.

The U.S. representatives to the commission argued for a higher limit but agreed to the reduction because it was in the best interest of the country, said Russell F. Smith, deputy assistant secretary of commerce for international fisheries.

Smith, who works for the National Oceanic and Atmospheric Administration, said the measure helps to ensure that tropical tunas, including bigeye, are better managed by the commission.

Except for China — which agreed to a 25 percent reduction — each of the major developed countries’ longline fleets agreed to a 10 percent reduction in their bigeye tuna catch, he said.

Observers said China agreed to a larger cut to make up for reductions it was supposed to take in earlier years.