by Eric Ettlinger
The long-awaited storm that began January 19 dropped ten inches of rain over parts of the Lagunitas Creek watershed. The exceptionally dry ground absorbed a lot of that, but couldn’t absorb it all, and streams rose quickly. Adult coho salmon swam and jumped into many of the local streams, including into at least one headwater stream where they haven’t been seen in years. By late last week stream flows had declined enough for MMWD biologists to conduct spawner surveys and document the unusually late peak in coho spawning. We counted 35 new coho redds and 104 adult coho salmon. This brings the preliminary season total to 103 redds and 377 coho observations. The live fish count is likely an overestimate due to counting the same fish over multiple weeks, but the redd count is a more accurate measure of the size of the run. To date we’ve counted four times more redds than were built by the previous generation of coho salmon three years ago! We don’t expect these numbers to go much higher since late January is typically the very end of the coho spawning season. However, last week’s murky water may have prevented us from seeing every redd and we may find a few more when we survey again later this week.
A striking aspect of this season’s coho run has been the very high proportion of coho jacks. Jacks are small, two-year-old male salmon that return from the ocean one year earlier than most adult coho. More than half of the spawners seen last week were jacks, which is significant since the vast majority of their siblings are still out in the ocean. Lots of jacks this year suggests that far more coho will return to Lagunitas Creek next year.
One last bit of good news was the observation of coho spawning on MMWD property at the mouth of a small tributary to Lagunitas Creek called Dog Creek. Dog Creek used to flow through a cylindrical metal culvert that was too small to handle large floods and also impeded the natural movement of gravels to Lagunitas Creek. MMWD crews replaced the cylindrical culvert with an open-bottomed arch, and the creek quickly built a gravel delta at its confluence with Lagunitas Creek. Last week a pair of coho became the first salmon to spawn in this new habitat.