Published in Commercial Fisheries News, Letters, April 2011
By Kelsey Abbott
“You don’t need to be a PhD to recognize a problem,” says Mark Wiegardt, owner of Whiskey Creek Shellfish Hatchery in Netarts, Oregon. “I’m not a scientist. I’m not a biologist. There’s a lot of things I’m not,” he says, “but I know shellfish.” And he knows problems.
Zero production is a problem.
As one of the three major shellfish hatcheries on the West coast, Whiskey Creek—which supplies 80% of the region’s shellfish growers with oyster seed—had never had a production problem. But for three to four months in 2007, Whiskey Creek didn’t produce any viable oyster larvae. In 2008, the hatchery saw some production, but at 20 to 25% of normal levels. This lost production left local shellfish growers without seed and left Wiegardt wondering if his 30-year-old business would survive.
Wiegardt reevaluated the hatchery’s procedures. He checked bacteria levels and installed protein skimmers. He hired Alan Barton. Both men were stumped—until Barton decided to monitor pH levels. That, says Wiegardt, is when “we noticed we had a problem.” Larval survival seemed to fluctuate with the pH level of the seawater. When the water
was more acidic (lower pH level), larval mortality was high. If Whiskey Creek was going to produce larvae, they would have to work around the conditions that killed the larvae. To do that, they’d have to predict changes in water chemistry. And to do that, they needed the “Burkilator.”
The Burkilator, created by Burke Hales and Jesse Vance of Oregon State University and installed at Whiskey Creek in April 2010, measures the partial pressure of carbon dioxide (pCO2) in the seawater flowing into the hatchery. Using pCO2 as a proxy for pH, the Burkilator provides Whiskey Creek with real-time continuous measurements of water temperature, salinity and acidity. By analyzing these data along with wind velocity measured from a nearby NOAA buoy, Wiegardt and Barton found that north winds caused upwelling, which brought more acidic waters to the surface. Upwelling, however, occurred one to two days after the winds came from the north. If they timed things properly, Wiegardt and Barton would be able to spawn the oysters before the acidic water came to the surface. Now, when the winds come from the north, they fill the tanks late in the day (when the pH is higher due to natural daily fluctuations) and start spawning.
The success of Whiskey Creek’s monitoring system and the resulting ability of the hatchery operators to maximize production by “working around the problem” spurred the creation of a water chemistry monitoring network throughout the Pacific Northwest. The Pacific Coast Shellfish Grower’s Association (PCSGA) monitoring program includes the
monitoring station at Whiskey Creek as well as stations in Bellingham, Dabob Bay, Gray’s Harbor and Willapa Bay, Washington. In 2011, all sites will monitor pH, temperature, salinity, dissolved oxygen, nutrient concentrations, bacteria levels and larval performance, while some sites will also monitor continuous pCO2. What does all of this have to do with Northeast fisheries? Maybe everything. Shellfish hatcheries in the Northeast haven’t reported lost production due to acidic waters, but hatcheries in the Northeast haven’t been monitoring pH or pCO2 in their waters either.
Mark Wiegardt warns Northeast hatchery operators, “You don’t have to go through all the grief we did if you just get the damn monitoring system.” Hatchery operators and lobstermen in the Gulf of Maine are taking Wiegardt’s advice to heart as they pursue plans to establish a regional monitoring network. In the meantime, a pilot project is set to begin monitoring pH levels at Muscongus Bay Aquaculture. By monitoring the acidity of seawater throughout the Gulf of Maine, hatchery operators lobstermen, fishermen and scientists would gain a better understanding of the fluctuations in the marine ecosystem—and, like Wiegardt, may be able to predict changes in water chemistry to maximize productivity.