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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 03

Lagunitas Creek Spawner Update: December 3, 2019

Posted on December 3, 2019 at 4:57 PM by Emma Detwiler

The rain has finally arrived and adult salmon have returned to the Lagunitas Creek watershed. After an unusually dry start to the season over five inches of rain fell during the last week. Stream flows are now high enough to allow salmon to migrate through Lagunitas Creek and into tributaries such as San Geronimo Creek and Devil’s Gulch. This is a good time to look for Coho Salmon jumping at the Inkwells, where San Geronimo Creek flows into Lagunitas Creek.

The extended dry season may have delayed spawning for most Coho Salmon, but three other salmon species didn’t wait for the rain. For the third year in a row Pink Salmon (Oncorhynchus gorbuscha) have been seen in Lagunitas Creek. Starting in mid-September, biologists with the California Department of Fish and Wildlife (CDFW) observed adult Pink Salmon and their distinctively small redds (gravel nests). A total of ten Pink Salmon redds were observed through early November. In early October a single Chum Salmon (O. keta) was observed, followed by nothing until last week, when another fish was seen. No more than six individuals of this regionally rare species have been seen each season since 2002. The third species to arrive was Chinook Salmon (O. tshawytscha), and so far we’ve observed 41 adult Chinook Salmon and 13 redds. November is typically when we see Chinook Salmon and this year’s run has so far seemed fairly typical. The salmon pair in the photo below consists of a female Chinook Salmon and a male Coho Salmon. There’s some evidence that this pairing can produce hybrids, although no Chinoho (Cohooks?) have yet been documented in Lagunitas Creek.

The main attraction (due to the fishes’ relative abundance and bright colors) is the Coho Salmon run, which should be getting underway right now. Flows are currently (no pun intended) too high and muddy to see the fish, but over the next few days Coho Salmon will hopefully be visible migrating, jumping, fighting, and spawning throughout the watershed. Biologists with MMWD, CDFW, the National Park Service, and the Watershed Stewards Program will be counting them.
 Photo By Sherry LaVars/Marin IJ


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