Local oysters affected by acidic water; corrosive water threatens Hood Canal

Taylor Shellfish Farms hasn’t had much luck in the past few years.

Its Dabob Bay hatchery, on the north end of Hood Canal, produced 40 percent the oyster larvae needed for a complete catch in 2008, and 20 percent in 2009. This year, spokesman Bill Dewey is optimistic; despite recently published research suggesting water quality problems are here to stay.

Resulting from a recent study, scientists at the University of Washington and the National Oceanic and Atmospheric Administration announced Monday, July 12 that the deep waters of Hood Canal are experiencing remarkably high levels of acidity, which means shellfish are fighting for their lives – and more often than not, they’re losing.

The study, which was published online and will appear in the Estuarine, Coastal and Shelf Science journal this August, found that highly acidic ocean water, or water with a low pH level, is causing an increase in the Hood Canal’s acidity by 24 to 49 percent. That could increase to 80 percent years down the line, according to the study.

Oxygen shortage

This compounds existing water quality concerns, such as a lack of dissolved oxygen. Low levels of dissolved oxygen come from increased carbon dioxide, which is caused by leaky septic systems, the canal’s slow water circulation and nutrient-filled runoff.

The lack of oxygen has surely made the last few years a challenge for Hood Canal hatcheries as shells dissolve in the highly corrosive water, allowing a fraction of the projected catch to survive.

However, Dewey hasn’t lost hope. He knows the future is grim, but, as he recalls, shellfish farming has always required that he adapt to environmental shifts.

“I think the Jefferson County industry has been largely unaffected,” Dewey said.

The major reason: Taylor Shellfish Farms has expanded its Kona, Hawaii hatchery operation to fill the void. The firm has also invested in sophisticated monitoring equipment that allows hatchery workers to follow chemical changes in the water before allowing it into their shellfish beds.

Wind, water

Dewey said these recent findings remind him of the impact of wind on shellfish farming. While working for Dick Steele in the 1980s as a shellfish biologist at Rock Point Oyster Company in Quilcene, he said he could always tell what mood his boss would be in by testing the direction of the wind on his way to the hatchery.

“If it was a south wind, he would be fine,” he said. “But if it was blowing from the north, he would be a bear.”

At the time a north wind meant larvae would be blown down the canal, thus he would get a smaller catch. But now Dewey knows that wind causes “upwelling” events – a break in the water’s thermocline layer – that allows deep, stagnant water to mix with the warmer water above it. The temperature drops significantly, creating unfit conditions for shellfish production.

Corrosive ocean water finds its way into the canal through upwelling. Upwelling allows roughly 50-year-old water to rise and further acidify the canal. The study’s scientists have called for Congressional action, asking the body to mitigate carbon dioxide emissions immediately. However, efforts to slow climate change mean little to Dewey concerning the here and now.

“Even if we change policy now, we still have 50 years of bad water,” he said. “That means we can’t expect to see improvement in our lifetime.”

For now, Dewey feels the best option is to adapt – something in which Hood Canal’s shellfish industry is well versed.

“For us the problems are immediate,” he said, “so the solutions must be immediate.”

ptleader.com, 26 July 2010. Article.

  • Reset


OA-ICC Highlights

%d bloggers like this: