Climate: Ocean acidification threatens Alaska’s burgeoning shellfish hatchery industry

Costly seawater treatment may be needed by 2040

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Shellfish are particularly vulnerable to ocean acidification. @bberwyn photo.

Staff Report

FRISCO — Ocean water around parts of Alaska is acidifying so fast that shellfish hatcheries may soon have to use costly treatment systems to continue commercial operations.

“Our research shows there could be significant effects from ocean acidification on Alaska’s emerging shellfish hatchery industry in a matter of two and half decades,” said Jeremy Mathis, Ph.D., an oceanographer at NOAA’s Pacific Marine Environmental Laboratory and a co-author of the study, published this week in PLOS ONE.

“We need to continue to partner with industry and other stakeholders to make sure we’re providing the environmental intelligence needed by industry to answer key questions and make decisions to meet these challenges,” Mathis said.

In a well-documented climate change impact, absorption of carbon dioxide pollution is making global oceans more corrosive to calcium carbonate minerals which shellfish need to build and maintain shells.

In coastal Arctic areas, melting glaciers, upwelling of CO2-rich waters and the natural decomposition of plant-life all intensigy ocean acidification. To track the impacts, scientists with  NOAA’s Pacific Marine Environmental Laboratory in Seattle and the University of Alaska Fairbanks worked with the Alutiiq Pride Shellfish Hatchery in Seward, Alaska, to monitor seawater chemistry for nearly a year.

Their goal was to measure the potential effects of changing ocean chemistry on the growth of oyster, clam, scallop and other shellfish larvae or seed, and they found that the ocean changes significantly by season. There is currently a five-month window during spring and summer when growing conditions favor larval shellfish, followed by periods of poor growing conditions in autumn and winter.

But under some predicted scenarios for carbon dioxide emissions this five-month window for growing shellfish could close as early as 2040. The hatchery would then only be able to produce viable shellfish seed if it installed costly mitigation efforts to modify ocean water entering the facility.

Currently, shellfish farming in Alaska involves mostly small-scale operations focused on oysters and mussels, but there is a growing interest in scaling up commercial operations as communities embracing shellfish farming to diversify the local economy and create jobs.

Currently, Alutiiq Pride is the only shellfish hatchery in Alaska that can provide seed stock to local residents that otherwise have to buy seed from outside the state. However, as the cost of producing seed stock increases in states like Washington and Oregon due to rising ocean acidification levels, hatcheries will be looking for alternative locations to supply large-scale operations. The growth of shellfish farming increases the need for effective monitoring of ocean waters.

“A key to tracking ocean acidification and its effects is our ability to make continuous robust measurements of the carbonate system in hatchery settings to understand how it varies over time,” said Wiley Evans, Ph.D., of the University of Alaska Fairbanks, the lead scientist on the project. “We’ve come a long way in our ability to monitor ocean acidification.”

“Ocean acidification has had major impacts on hatcheries in the Pacific Northwest and we wanted to evaluate what, if any, impacts could be expected here in Seward,” said Jeff Hetrick, owner of Alutiiq Pride. “The results have been alarming.”

The study reinforces broader research showing that Alaska’s commercial and subsistence fisheries are vulnerable to ocean acidification.

Ocean acidification monitoring will continue at the Alutiiq Pride Shellfish Hatchery and will expand to at least one other site along the southeast Alaska coast in late 2015.

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