$100 for a spicy ahi poke bowl? Well, possibly.

Hawaii fishermen and seafood lovers may have a new reason to heed the long-standing warnings about the serious impacts of climate change, according to federal scientists in Honolulu.

The latest research shows global warming and ocean acidification will have a significant effect on large pelagics, such as tuna and swordfish, over the 21st century.

National Oceanic and Atmospheric Administration scientists Phoebe Woodworth-Jefcoats and Jeff Polovina conducted an investigation that projects up to a 75 percent decline in the abundance of big fish in the central north Pacific as plant-like organisms called phytoplankton change in density.

“The habitat of tuna will expand but the density per unit area will go down,” Polovina said. “It’s going to be a problem because the density of fish relates to catch rates that have economic importance. Lower density means lower catch rates.”

This could mean far fewer fish to be caught and sold in local markets and higher prices for consumers. The Hawaii commercial fishing industry alone generates roughly a half-billion dollars in sales annually and provides 11,000 jobs, according to a recent report. The Aloha State’s recreational fishery adds another 7,000 jobs and more than $773 million in total sales.

The fishing industry is generally more concerned with short-term impacts from weather changes like those caused by El Nino, Polovina said.

“This is a long-term slow change on a decadal basis,” he said. “It’s sort of like rust on your car that is slowly going along.”

Current fishing levels won’t be sustainable if productivity decreases substantially, Polovina said. He added that this will create problems for the fishing industry that needs to plan for financing new fleets and raises food security issues too.

But not all scientists are concerned.

Paul Dalzell, a senior scientist with the Western Pacific Regional Fishery Management Council, which sets fishing quotas and makes recommendations on how to maintain sustainable stocks, said he’s aware of concerns over how climate change will impact different organisms but doesn’t think there’s much to be done about it.

“If the U.S. shut down all its industry and we all went to live in huts, it would be a needless sacrifice,” he said. “There’s little we can do as an organization to modify climate change and there’s little the U.S. can do to modify climate change because of all the other countries in the world.”

Next month the Western and Central Pacific Fisheries Commission will meet in Manila to consider a three-year management plan for the overfished skipjack, yellowfin and bigeye tuna. But the debate isn’t expected to focus on the impacts of climate change.

Wespac’s fall newsletter says the commission will consider the battle between longliners who catch adult tuna and purse seine fishermen who scoop up the adult fish and juveniles alike because their nets don’t discriminate.

Hawaii Department of Land and Natural Resources Chair Bill Aila said it would be hard to plan for pelagics, but didn’t dispute the impact of ocean acidification.

“The whole food chain is primarily dependent on phytoplankton and zooplankton,” he said. “So if the zooplankton and the phytoplankton can not get their skeletons in place, then they don’t exist. And if they don’t exist, everything that depends on them on up no longer exists.”

State aquatic biologist Don Heacock said he thought the study’s projections seemed “absolutely” possible.

Especially given fishing’s role in Hawaii’s culture, he said it’s important to do everything possible to prepare for the effects of climate change. He said this effort could start on land by doing things like accounting for sea-level rise in planning, taking steps to control erosion and working harder to become food self-sufficient.

Polovina said scientists have seen previous climate change projections become reality over the past decade.

“The ecosystem is responding,” he said, adding that there will always be surprises.

One of the surprises in the study was a significant increase in the projected changes in the catch of large fish in areas outside the central north Pacific. In the California current region, the scientists project a 43 percent increase in the abundance of big fish.

Woodworth-Jefcoats said although the projections are based on models, there’s a lot of work that goes into them and they’re verified as best as possible.

“A lot of how we predict the weather every day is models,” she said. “It’s not just a bunch of math on the wall.”

Polovina said the study will be published soon in the journal Global Change Biology.

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