Will Hood Canal experience a fish kill this year?September 22nd, 2013 by cdunagan
UPDATE, Sept. 26
The Hoodsport monitoring buoy was placed back online yesterday. The dissolved oxygen levels at the surface are much higher now than they were two weeks ago, coming up to about 9 milligrams per liter at a 10-foot depth. But oxygen levels in the middle layer remain about the same — about 2.5 milligrams per liter. And the middle layer still contains less oxygen than levels close to the bottom, which is getting an infusion of heavy seawater from the ocean.
A south wind could still bring low-oxygen waters to the surface,
but I don’t believe the levels are low enough to cause a fish kill.
Still, the low-oxygen water could force deep-water fish to move
upward in the water column. I’m waiting to hear from divers if they
are seeing anything unusual, and I’ll let you know if conditions
take a turn for the worse.
Are we about to see one of the infamous fish kills that we have observed in Southern Hood Canal in past years?
I am unable to sound any alarms at this time, but if you live in the Hoodsport-Potlatch area or are scuba diving nearby, you might want to watch for dead fish on the surface, rockfish or shrimp swimming in shallow water, or wolf eels and octopuses acting strangely.
Usually, we can look to the monitoring buoy offshore of Hoodsport to answer questions about whether fish are starving for oxygen. The buoy tells us about dissolved oxygen levels at all depths. I watch this buoy every fall for clues about dangerous conditions, such as when the surface and middle layers of Hood Canal become depleted of oxygen.
Unfortunately, the Hoodsport ORCA buoy has been down for most of the past 10 days. University of Washington technicians are trying to get it back in operation, but it appears to be an Internet/local-network problem at the moment.
As of Sept. 10, the surface layer at 10 feet deep was down to less than 2 milligrams per liter, an alarming level, and conditions were not much better at 66 feet. (See chart.) That means there is a lot of low-oxygen water that could be brought to the surface when we get a wind blowing out of the south. Well, we’ve had some moderate south winds today, and I’m wondering what is happening out there right now.
South winds blow the surface layer away and bring low-oxygen water up from the depths. Fish may come to the surface seeking better conditions, but they may find oxygen levels even worse as they go up — and the fish have no idea that better conditions may lie below.
So far, I have not seen any concerns posted on the Facebook pages of divers who may have gone out recently. Feel free to post a comment to this blog or send me an email (firstname.lastname@example.org) if you see or hear anything that can contribute to the discussion.
A statewide hotline used to report oil spills also will take your calls and alert biologists to reports of dead fish. That number is (800) OILS-911.
With some luck, the UW folks will have the Hoodsport buoy back on line in the next couple days and we’ll see if conditions have improved or gotten worse. For now, we’ll just have to wait. The chart is generated by the Data Explorer at the Northwest Association of Networked Ocean Observing Systems (NANOOS). (Click on “regions” to get to Puget Sound.)