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Point of View: Seafood’s future hinges on reducing carbon pollution
By Bruce Steele
June 01, 2014
A decade ago, Japanese researchers showed that seawater soured by carbon pollution would hamper sea urchins’ reproductive capabilities. I read their report and saw trouble on the horizon. As a commercial urchin diver in California, I hoped this trouble would stay far away. Now it’s here.
Christina Frieder at UC-Davis has demonstrated that waters acidified to pH 7.8 — a level already detected along the West Coast — can reduce fertilization success by 20 percent in red sea urchins, which are harvested from California to Alaska. Frieder states that 60 percent reductions in fertilization success may occur in the decades ahead as pollution pushes seawater pH down to 7.5. This means that red sea urchins will have a harder time recruiting into the fishery, and they will be less abundant. Surface waters had an average pH of 8.2 in pre-Industrial times; acid from carbon emissions has reduced that to about 8.1 in today’s ocean, and it’s heading south fast.
Now ocean acidification is my problem. If you work in seafood, it’s yours too.
Red king crab suffers 100 percent mortality of larvae after 90 days in seawater at a pH of 7.5. Oysters, mussels, clams, abalone and some scallops are vulnerable, which shellfish farmers are learning the hard way. Corals that shelter vulnerable fish populations in much of the world are at risk. Shells of pteropods, common zooplankton that are a key food source for salmon, are already dissolving in Pacific Northwest waters. Two recent studies found that modest levels of acidification can impair growth in American lobsters. Direct impacts on fish are also becoming clear: Some fish lose their ability to smell and evade predators or distinguish them from their own prey. The catalog of harm includes damage to organ tissues, neurological functions, growth and reproduction.
For the seafood industry, some consequences are now inevitable. But there is no place to hide, so we had better defend ourselves. Both the causes and the consequences of acidification can be reduced.
How to curb the causes? Strong policies to reduce carbon emissions would be a good start. Without those, everything else we do will amount to an epitaph.
This industry can and should push Congress and the Obama administration to protect fisheries from carbon pollution. California and nine Atlantic states from Maine to Maryland have embraced market-based systems — akin to individual fishing quotas — to cut emissions. This hasn’t broken their economies. Now even China is trying a market system to cut emissions in five cities. India has launched the world’s first nationwide cap-and-trade regime to curtail carbon pollution.
Protecting seafood supplies will require especially deep cuts in carbon pollution. A recent paper published in Nature by Steinacher, et al., illuminates the geochemical vulnerability of productive fisheries: If CO2 emissions push atmospheric concentration beyond 550 parts per million, more than 90 percent of waters where coral reefs grow are likely to become chemically hostile to many corals and other calcifiers.
How to reduce harm? We are learning tools for adaptation. To save collapsing “seed” supplies for Pacific Northwest shellfish farms, hatcheries have found effective but costly ways to measure and manipulate seawater chemistry in their tanks. That’s how they protect larvae that were dying by the billions in corrosive waters during their most vulnerable first days of life. In coastal bays, researchers along the West Coast are investigating whether photosynthesis by sea grass can soak up enough CO2 to protect neighboring calcifiers from acidifying waters, a research priority identified by Washington’s Blue Ribbon Panel on Ocean Acidification.
Can we protect fish stocks in open waters? Maybe. No-fishing areas, which I fought for many years, do increase density and size of formerly fished stocks. That might help protect reproductive capacity of broadcast spawners like red sea urchins: Acidification makes their sperm swim slower and survival time of urchin sperm limits successful fertilization. Another approach is increasing the size limit of sea urchins that can be harvested, to increase sea urchin densities and spawning success.
Working with researchers from two University of California campuses, the sea urchin industry has funded and facilitated a long-term study of larval sea urchin recruitment. Our one-of-a-kind data set shows trends in sea urchin survival at 15 sites. If decreased red sea urchin recruitment does show up, we will see it in the data. Keeping track of recruitment has helped us manage our fishery in the past and it will help us recognize when we need to protect spawning capacity. But that’s only treating the symptom.
Frieder’s findings on red sea urchins are a harbinger of trouble for the whole ocean. To stay in business, seafood producers of all kinds will need to belly up to some tough new management practices. We will also need to become effective champions for pollution controls that most of us have ignored until now.
Bruce Steele has spent more than 40 years as a commercial diver and fisherman in Oregon and California. He is a longstanding leader in resource management and industry associations.