Tuesday, October 2, 2012

Coho Salmon Passage - Feeding the Quilcene River Ecosystem

Releasing adult coho salmon
above the hatchery weir
Like many hatcheries, Quilcene National Fish Hatchery (located on the Olympic Peninsula) is equipped with a weir. A weir is similar to a dam, except that a weir controls the upstream flow of fish instead of controlling the downstream flow of water. At Quilcene NFH, the weir blocks returning adult coho salmon so that the hatchery can collect the number of fish it needs to breed future salmon generations and provide fish to its affiliated tribes for subsistence. In addition to these human needs, the ecosystem upstream of the hatchery needs fish, too.

Over the last 10 to 20 years, scientists have found that naturally-spawning salmon provide a myriad of ecological benefits to aquatic and terrestrial ecosystems, including delivering nutrients as natural fertilizers and serving as "ecosystem engineers" while digging their nests in the bottom of the stream. To help meet these ecosystem needs, our office is working with Quilcene NFH to intentionally pass adult coho salmon upstream of the weir.

This year, our target is to pass a total of 800 coho salmon over the weir. September 19 marked our first passage day when we released 170 fish into the Big Quilcene River above the weir.

A tagged coho salmon to be released above the hatchery weir. 
(Note the yellow tag near the rear of the dorsal fin.)

In addition to passing fish, we are also evaluating what these fish do and where they go afterward. To accomplish this, we tag the fish prior to release and later survey the river and streams to identify where the fish spawn and how many stay upstream versus return to the hatchery. We’ll write more about these evaluations later, but for now we are happy to see salmon spawning in the Big Quilcene River and delivering much-needed nutrients to support the ecosystem that also includes federally-listed Puget Sound steelhead.


1 comment:

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