Coho spawning activity in the Lagunitas Creek watershed seems to have hit a peak recently, with 72 new redds (gravel nests) observed last week and only 18 this week. We saw all these redds in Lagunitas’ two main tributaries, San Geronimo Creek and Devil’s Gulch. Since December 21st high stream flows have prevented us from surveying the main stem of Lagunitas Creek, where we typically observe between a third and a half of all coho redds.
To date we’ve observed 179 coho redds, which is above average but below the pace of the parent generation three years ago. The chart below shows cumulative weekly observations over the last six years, showing the parent generations (dashed lines) and offspring generations (solid lines) three years later. All of these runs were close to complete by mid-January, and we don’t expect to see much more coho spawning activity in the next few weeks. However, next week flows will be low enough to wade safely in Lagunitas Creek, and we’ll finally get to look for the redds built during the last three weeks. Hopefully, most of those redds will still be visible.
- Eric Ettlinger, Aquatic Ecologist