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Environmental reporter Christopher Dunagan discusses the challenges of protecting Puget Sound and all things water-related.
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Oxygen in Hood Canal bounces back overnight

September 22nd, 2010 by cdunagan

UPDATE: Sept. 24, 2010

Conditions have remained pretty much the same the last couple of days, although the intrusion of dense higher-oxygen water from the ocean is beginning to create a thicker layer at the bottom of Hood Canal. The middle layer of low-oxygen water remains fairly thick, but the upper layer with higher oxygen concentrations is still providing fish some relief. South winds remain a threat, as I’ve explained for the last few weeks.

One can observe the three layers in the upper graph. The lower graph shows changes over the past week or so. Notice how oxygen concentrations are rising in the deep layer.


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Fish in southern Hood Canal got a little more room to breathe this morning, as oxygen levels rose in the top 30 feet of the water column.

Many spot prawns died Tuesday near Hoodsport Hatchery while swimming into fresh water to get oxygen.
Photo by Wayne Palsson, WDFW

I described the latest observations from researchers in a story published this morning on the Kitsap Sun’s website. A story written for today’s Kitsap Sun also contains some important observations about events of the past two days.

The rapid recovery may have been largely the result of a seiche, in which waters pushed away by winds came back when the winds ceased. In terms of the overall conditions, nothing major has changed, however, and south winds could trigger another fish kill.

One thing I found interesting but disturbing was that many of Hood Canal’s famous spot prawns were making a deadly choice. They were swimming into freshwater inlets, where the waters were more oxygenated, only to die when they could not survive the low salinity. I understand that the greatest losses were at the outlet of the lower Cushman Dam at Potlatch, where waters from the North Fork of the Skokomish River come into Hood Canal.

Here’s how the oxygen levels have changed at Hoodsport since 11 o’clock last night and 10 o’clock this morning. Note the blue line, which is about the 9-foot level, as measured by a monitoring buoy that operates around the clock.

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4 Responses to “Oxygen in Hood Canal bounces back overnight”

  1. BlueLight Says:

    Beside oxygen in parts per million, do your scientists have any numbers associated with tribal “rape” of the canal?

    http://pugetsoundblogs.com/everyday-ck/2010/09/24/the-rape-of-hood-canal-wa/

  2. cdunagan Says:

    Poaching of fish, shellfish and wildlife is a serious problem throughout Washington state, as Rich Jacobson points out in his blog post. State enforcement officers have never been able to keep up with all the illegal activity, and the number of officers has been continually reduced by state budget limitations.

    If you read the enforcement report mentioned in the blog, you’ll see that illegal activities are committed by both tribal and nontribal fishermen, sport and commercial, as well as hunters. Officers tell me that impacts on the resource are serious, but actual quantities of fish and shellfish taken illegally cannot be assessed because most violations are never reported.

  3. BlueLight Says:

    Hmmm, maybe we ought to put more money into enforcement and less money into never-ending research and advocacy. Seems to be a much bigger impact than the occasional south wind. Likewise… I noticed a bit of investigative journalism when a Navy ship was suspected of impacting a few oysters. Any chance you’re gonna turn that zeal toward this?

  4. cdunagan Says:

    UPDATE: Sept. 24, 2010

    Conditions in Hood Canal have remained pretty much the same the last couple of days, although the intrusion of dense higher-oxygen water from the ocean is beginning to create a thicker layer at the bottom of Hood Canal. The middle layer of low-oxygen water remains fairly thick, but the upper layer with higher oxygen concentrations is still providing fish some relief. South winds remain a threat, as I’ve explained for the last few weeks.

    One can observe the three layers in the upper graph. (See top of this entry.) The lower graph shows changes over the past week or so. Notice how oxygen concentrations are rising in the deep layer.

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