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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 05

Peak Spawning Season Is Here!

Posted on December 5, 2014 at 7:46 AM by Ann Vallee

by Eric Ettlinger, Aquatic Ecologist

We’ve had an exciting couple of weeks on Lagunitas Creek with lots of both rain and fish. In that time we’ve received over eight inches of rain and Lagunitas Creek flows increased from 20 cubic feet per second to a peak of 1,800 cfs. During a break in the rain on Monday we observed 63 coho, 28 Chinook, and one chum salmon.

The stats for the season so far include:
  • 117 coho, 74 Chinook, and two chum salmon
  • 24 coho redds (gravel nests), 20 Chinook redds, one chum redd, and nine redds we couldn’t classify
Our coho observations are far above average for this early in December and we’ve already seen the second-highest number of Chinook recorded for the creek.

Not only have the numbers been unusual, but so have the interactions between salmon species. On Monday we saw a male chum salmon attempting to spawn with a female Chinook. This confused fish was driving off three male Chinook salmon and even biting and wounding the female, presumably because he occasionally mistook her for a male. These species can’t hybridize, so hopefully the female Chinook survived the encounter and eventually spawned with her own kind. Male coho have also been seen attempting to spawn with female Chinook, maybe because these extra-large females are simply irresistible.

Today we observed salmon jumping through Roy’s Pools (at the western edge of the San Geronimo Golf Course), at The Inkwells (the confluence of San Geronimo and Lagunitas Creeks), and spawning at the Leo T. Cronin Fish Viewing Area. We’re hoping flows will recede enough to get into the creek on December 9, but if anyone sees salmon before then, particularly in Devil’s Gulch or San Geronimo Creek, please share your observations in the comments section below. Thanks!

Chinook and chum on redd2

A female Chinook salmon (left) and a male chum salmon


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