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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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Jan 05

High Hopes for Lagunitas Creek Salmon

Posted on January 5, 2016 at 10:50 AM by Emma Detwiler

by Eric Ettlinger, Aquatic Ecologist

The new year is starting off happy on Lagunitas Creek, at least for us biologists. The storms just before Christmas dropped over six inches of rain in the watershed and raised stream flows to their highest level of the season. Surveys documented over 200 coho salmon and 94 new redds since those rains. Last week's redd count (53) was the highest single-week count in a decade. To date we've counted over 400 live coho redds, which already beats last year's totals.

High stream flows have allowed salmon to swim into San Geronimo Creek and Devil's Gulch, where we counted 49 and 21 coho redds, respectively. Those are respectable redd counts for an entire season, with roughly a month left in this spawning season. We've even heard reports of good numbers of coho in the small tributaries to San Geronimo Creek, where they've been extremely scarce in recent years.

Some caution should be exercised before celebrating all this good news. We're still a long way from an average run (250 redds), let alone a record run (634 redds). This cohort migrated to the ocean in record numbers in 2014, and so far we've seen less than 3% return. We were hoping that a record smolt migration would translate into a record spawning season.

And lastly, the hundreds of thousands of coho eggs now incubating in their gravel beds are vulnerable to the kind of El Niño flooding currently predicted. Hopefully there are lots of salmon that have yet to spawn, and hopefully we'll get enough rain to fill our reservoirs but not enough to wash away salmon eggs.

Here's hoping.

 coho jack DG
 A coho salmon jack (two-year-old male) in Devil's Gulch.
Photo credit: Daniel Hossfeld

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