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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 29

Lagunitas Creek Spawner Update: 1/29/18

Posted on January 29, 2018 at 9:48 AM by Emma Detwiler

Written by: Aquatic Ecologist Eric Ettlinger

January has been fairly typical in terms of salmonid activity in Lagunitas Creek. That’s a marked contrast to December, when it simply didn’t rain and very few salmon spawned, and November, when four salmon species were spawning. This month we’ve had three decent storms that allowed spawners to migrate into tributary streams, which has kept us busy conducting surveys all over the watershed. Over a four-day period we counted 155 coho salmon, which is a respectable peak spawning week. Since then our coho observations have dropped off while our steelhead observations have ramped up, which is also typical for this time of year.

But a few things have continued to be unusual. First, somewhere around half, maybe more, of the coho we’ve seen have been jacks. Jacks are small, two-year-old males that return to spawn after less than a year in the ocean. The last time we saw this many jacks was in 2002-03, which turned out to be a preview of the large coho run of 2003-04. Maybe this year’s jacks also predict good things for next year.

Not to be outdone, steelhead numbers are also unusually high. To date we’ve counted 33 steelhead, which doesn’t sound like a lot, but steelhead are easy to miss. They’re quite cryptic and spawn quickly. The last time we saw this many steelhead in January was 2008. That run ended up being one of the largest ever documented in Lagunitas Creek. Steelhead will continue to spawn through April, so we won’t know for a while if the run is one for the record books.
Steelhead male (large grey fish), female (large fish below male), and a coho jack at far right. A juvenile steelhead can also be seen below the female, trying to spawn with her.


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