Saturday, September 5, 2015

They're BAAAAAACKKK...

King Salmon on the Deschutes estuary
     In early September in the Pacific NW we got some of the first deep soaking rains for several months.  A prolonged hot and dry series of months finally broke to an unseasonal fall storm, coming several weeks earlier than normal.

     Normally we moan about the rain, but nearly everyone I knew was profoundly grateful.  I could almost feel the trees drinking it up and the rain-washed leaves finally able to collect sunlight more efficiently. The amphibians started to move too: Glen and Nancy and I went out on a couple of very warm, rainy nights and watched tiny froglets leave the breeding pond for the winter woods.   Birds are starting to form winter guilds;  I watched chickadees, bushtits and nuthatches forage in a group, gleaning scale insects off of our Mock Orange.  The wheel of the season turns and this year it is rain that is turning that wheel.

     But that’s not all.

     For several weeks now, adult salmon have been coming in Puget Sound.  They head for the streams & rivers in which they were born and they wait for the right conditions to run the rivers.  Well, it turns out that rain triggers these movements:  the fresh rainwater cools the rivers, raises the water level and sends the strong unique scent of each river out into Puget Sound.  All these things make the migration possible.  So the salmon wait.

      Our local watershed is the Deschutes river and there are several types of salmon that are born in that river and return to it late in the summer.  There is a dam they have to pass through in order to get into the river, and they can only do so at high tide.  After the rains came this week, Nancy went to the dam and got these great pictures.  The salt water was unusually clear and almost teal-blue, no doubt because of the fresh rainwater coursing out of the dam.

     These are King (Chinook) salmon: the huge size, spotty blue-green backs and dark gums are distinctive to this species.  In late July into September, they leave the North Pacific ocean, head down the Straits of Juan de Fuca and into Puget Sound;   finally they head south to Olympia, to the Deschutes river where they were born.  A couple of hours before high tide, the dam closes, so they are forced to wait out the tidal cycle.  Today I went down at high tide and watched 60+ fish circling restlessly, trying to find a way through the dam and up into the impounded river.

     They don’t wait alone.  In the waters around the dam, Harbor Seals lurk.  Normally the fish can easily elude the seals, but in the enclosed waters near the dam, the seals are much more effective in catching them.  Here is a photo Nancy took: a Harbor Seal munching on its salmon catch, with a gull nearby hoping for scraps.

    Nor is it just the Harbor Seals that wait.  During the running of the salmon, there are always many people hanging over the rail, fascinated by this yearly event.

    Here are some sobering statistics:  a female salmon may lay as many as 4000 eggs, usually in a gravel bed nest or redd.  Of these eggs, maybe four will make it to adulthood and return to run the river to spawn.  What we see here are those rare survivors, returning once again to our waters, turning the wheel of life once again and bringing the promise of future generations.

Janet

Resources:  All photos by Nancy Partlow

5 comments:

  1. It's good to hear you have had rain up there. Just curious, since my husband grew up in Tumwater... aren't ALL the salmon in the Deschutes planted (i.e., introduced by humans) for sports fishermen? My understanding is the big fish had never naturally established themselves there, because of the steep waterfalls.

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  2. reference: http://www.streamteam.info/localstreams/streams/deschutes/

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  3. As you point out, the dam provides a reservoir for the predators to catch salmon. Like "fish in a barrel", the salmon are forced to try and evade seals in a circumstance that favors the seals. With the dam removed, the salmon would have a lot better chance of completing their migration successfully. In addition, the fingerlings would have brackish waters to transition to the Puget Sound and the ocean, once again improving their chances. Let's please find consensus as a community and remove the 5th Avenue Dam. thanks to the Partlow sisters for this blog.

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  4. As Katie (Nature ID) observes, the Deschutes run is largely "artificial" in that salmon could not get above Tumwater Falls until the fish ladder was built in the 1950's. There was always a chum salmon population at the base of the falls, but that part of the river is short and mostly tidal. Since the opening of the fish ladder, a wild population has established itself above the falls -- 5% to 10% of salmon stray from their home stream most years -- but most of the returning salmon are hatchery fish. A careful look at the salmon in the photo and several are missing their adipose fin -- the small back fin, clipped from all hatchery fish before release downstream. Between the chum salmon and the strays, seal and otter (and people) have probably been relying upon the mouth of the Deschutes for good fall fishing for a long time. Glen
    http://wdfw.wa.gov/hatcheries/mass_marking.html

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