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MMWD Blog: Think Blue Marin

Welcome to our blog! Written by staff at MMWD, “Think Blue Marin” explores all things water in south and central Marin—water supplies, conservation, new projects, watershed management, and more.

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Dec 23

Lagunitas Creek Spawner Update: December 23, 2019

Posted on December 23, 2019 at 9:22 AM by Emma Detwiler

Written by: Aquatic Ecologist Eric Ettlinger

Coho Salmon spawning in Lagunitas Creek often peaks in mid-December, particularly in years when early storms provide lots of water for migrating and redd building. The season has gotten off to a great start, at least in terms of rain, with five storms dropping over 11 inches of rain so far. So it’s with some anxiety that I’ve been asking “Where are all the fish?”

To date biologists with Marin Water and the Watershed Stewards Program have counted only 33 Coho salmon redds, which is about a third of normal for this time of year. We’re also not seeing adult salmon congregating in pools, which would be a sign that a lot more fish are simply waiting for the right conditions to spawn. This week’s wet weather has limited our survey opportunities, and I’ve got my fingers crossed that we’ll see a lot more salmon when we’re able to return to the creeks.

On a positive note, most of the Coho salmon we’ve seen have been in San Geronimo Creek, where their eggs aren’t as vulnerable to floods as farther downstream in Lagunitas Creek. Coho salmon females lay over 2,000 eggs each, and high survival of eggs would mean lots of fry next year (being an optimist is essential in this line of work.)

The photo below is of a recent Coho salmon redd in Lagunitas Creek, which demonstrates the impressive abilities of these fish. The margins of the redd are outlined in white and where the eggs have likely been laid in black. This particular redd was 38 feet long and 18 feet wide, and presumably excavated by a very industrious Coho Salmon female.

These fish continuously inspire awe with their abilities to migrate hundreds of miles, find their way back home, leap waterfalls, and build these massive structures, all with just a tail.
 spawner 2


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