Ocean acidification update from a shellfish grower on the front line

Over the past year, there have been many claims about ocean acidification and the impact on oysters. Many of those claims have withered under scrutiny. Taylor Shellfish is on the front line of dealing with environmental issues facing oyster growers. They agreed to answer questions about the current state of science and what they are facing. What follows are their answers and do not reflect our views. After meeting with Bill Dewey of Taylor Shellfish, we felt he provided an interesting perspective and some new information – some that supports and some that contradicts what has been in the public discourse. We don’t endorse everything here, but thought it was an interesting and useful contribution to the discussion.

Bill Dewey manages public affairs for Shelton based Taylor Shellfish Farms. He served on governor Gregoire’s Ocean Acidification Blue Ribbon Panel and serves today on Governor Inslee’s Marine Resources Advisory Council which advises the state’s ocean acidification response.

How is the shellfish industry in Washington doing? Better or worse than a few years ago? Why?

Oyster growers from Alaska to California have struggled in recent years to find seed and oysters to keep their businesses afloat.  Scientists from the National Oceanographic and Atmospheric Administration (NOAA) and various Universities have linked the oyster seed losses to ocean acidification. Shellfish growers’ understanding of what has caused these oyster seed shortages has evolved in recent years through research and dialogue.

The Washington Policy Center citing production numbers they obtained from Washington’s Department of Fish & Wildlife last October questioned in a blog post whether the oyster seed losses were real. (Editor’s note: To be clear, the Policy Center doesn’t doubt the reality of the losses, but we have questions about the cause, so we asked Mr. Dewey to provide his insight.)

Todd Myers and I met to discuss the issue and he generously offered to post our perspective.

Despite what the WDFW numbers might indicate from 2007 through 2009 the west coast shellfish growers experienced a severe oyster seed shortage.  Oyster larvae production at two of the four major seed producing hatcheries was down by about 75% during this period.  On top of that there was no significant sets of baby oysters in Willapa Bay from 2006 through 2012.  Many oyster growers in Willapa, one of the largest oyster producing estuaries in the country rely on natural recruitment of Pacific oysters to seed their beds. These seed production failures had a real and profound effect on shellfish growers.

Today the oyster seed situation is better.  An outstanding response from policy makers and an unprecedented collaboration between University, agency and industry scientists has advanced our knowledge dramatically in a very short period of time.  Created by the legislature in 2013, the Washington Ocean Acidification Center is studying the effects of ocean acidification on Washington’s marine resources.  Here is a link to a summary of what we know today.  Today, hatcheries have sophisticated monitoring equipment deciphering seawater chemistry as it is drawn from the ocean and automated systems treat the water to make it more conducive to oyster larvae survival.  Equipment has also been added to several buoys that are part of NOAA’s Integrated Ocean Observation System (IOOS) which allows shellfish growers and scientists to understand changes in the ocean chemistry around their hatcheries and farms. The NANOOS, the northwest coast’s IOOS streams local data in real time.

As a result of this response the tide has turned at least temporarily for shellfish growers.  Hatchery production has recovered and there have been a couple of years of decent natural recruitment in Willapa Bay.  While oyster seed supplies have improved they are still not adequate to meet growers’ needs.

What do we know about ocean acidification that we didn’t a few years ago?

Initial efforts to determine the causes of oyster larvae losses focused on the naturally occurring bacteria Vibrio tubiashi.  As it turns out, these problematic bacteria thrive in the water conditions created by upwelling off our coasts. Filtration systems were designed and installed to eliminate this bacteria only to find the oyster larvae still dying.  In 2008, NOAA ocean acidification expert Dr. Richard Feely informed shellfish growers at their annual conference that in his opinion the likely culprit of the oyster larvae deaths was changing seawater chemistry resulting from the ocean taking up anthropogenic carbon dioxide.

The ocean absorbs approximately a quarter of the anthropogenic carbon dioxide in the atmosphere.  This results in the formation of carbonic acid which reduces the oceans pH, making it more acidic.  Since first learning that ocean acidification may be our problem, hatchery operators have come to understand what matters most is the availability of carbonate ions.  These are the building blocks for the shells of the animals we grow and their availability diminishes with increased acidification.

The carbon dioxide from 250 years of burning fossil fuels has made the ocean surface waters 30% more acidic and reduced the availability of carbonate ions by 16%.  By the end of this century scientists are predicting we will have increased the acidity of the ocean surface waters by 100-150% and reduced carbonate ion availability by 50%.  Levels predicted for the end of the century throughout the world’s oceans are what we are experiencing on the west coast with upwelling events today.  A more troubling message for shellfish growers from the experts studying ocean acidification is that the water currently upwelling off the west coast is 30-50 years old.  So even if we address carbon dioxide emissions our waters will continue to get more acidic along Washington’s coast for decades to come because of what is already absorbed by the Pacific Ocean and in the pipeline heading our way.

Early reports suggested ocean acidification was “the” culprit killing billions of oysters.  We have since come to understand through monitoring and research that natural factors associated with summer upwelling off our coast results in reduced carbonate ion availability, a condition detrimental to the development and growth of oyster larvae.  Research suggests these conditions occurred about 11% of the time prior to the industrial revolution.  Due to anthropogenic carbon corrosive events for our oyster larvae are now happening an estimated 33% of the time and are more severe when they occur.

The combined oyster larvae production from the two hatcheries experiencing problems prior to 2007 was about 10-12 billion.  Based on what the oceanographers are telling us, we believe ocean acidification was a contributing factor to the 75% losses we were experiencing from 2007 to 2009. These losses could have amounted to billions.  Other contributing factors to the losses as noted in Todd’s blog include the wide natural variability in carbonate ions mentioned above.  It is also important to note these are larvae not market ready oysters.  A high percentage of them will die from natural causes and predation over the 2-4 years it takes to rear them from larvae to market.  “Billions” gets people’s attention and for better or worse is the descriptor used by media and policy makers describing the problem.

Taylor Shellfish has a second hatchery in Hawaii where we haven’t yet experienced the same ocean acidification related problems.  We have been expanding production capacity there to offset losses in our Washington hatchery.  A few years ago Willapa Bay’s Goose Point Oyster Company started up a hatchery in Hawaii in response to the West Coast oyster seed shortage.

For now we seem to have found a temporary solution by treating hatchery water to protect our larvae.  Juvenile and adult oysters thus far are not visibly impacted.  We fully expect under worsening conditions that the shellfish on our beds will eventually be impacted as well.  Unlike the hatchery, there is no way to control the seawater chemistry over thousands of acres of beds we have in the ocean.  To address this vulnerability the University of Washington and Oregon State University are working with shellfish growers to determine if selective breeding may yield ocean acidification tolerant oysters.

All these steps demonstrate ways in which the shellfish industry is adapting to changing seawater chemistry.

What can be done to improve the environment for the shellfish industry?

As mentioned, the response from policy makers and scientists to date has been outstanding.  The science on ocean acidification is rapidly evolving and having a coordinated review and response such as is done by the Marine Resources Advisory Committee is critical.  Efforts to expand this coordination west coast wide are well underway and similar efforts are being undertaken in New England and in the Chesapeake Bay.  Continued monitoring and the development of predictive models is also key for managing our response.

Governor Inslee included $1.7 million in his budget for continuing this critical work and at this point it has been included in both the House and Senate Operating budgets.

It is important to remember the impacts of ocean acidification extend well beyond shellfish.  They are just one of many calcifiers likely being affected by the changing ocean chemistry.  In addition scientists are finding other detrimental impacts beyond calcification.

If people are interested in learning more about ocean acidification, here is a link to the state’s website.

Todd Myers, Washington Policy Center, 19 June 2015. Article.

  • Reset


OA-ICC Highlights

%d bloggers like this: