by Eric Ettlinger
Salmon spawning season has returned to Lagunitas Creek, and so has one of its more sporadic and uncommon visitors. Chinook salmon, commonly known as king salmon, have been seen spawning in the creek for the first time in five years! The first sign of Chinook this season was a redd discovered on October 24, which would be exceptionally early for our resident coho salmon to spawn (a redd is a gravel nest where salmon lay their eggs). Their presence was confirmed on November 13 when three Chinook spawners were seen on that very same redd. Since then MMWD biologists have documented a total of seven Chinook salmon in Lagunitas Creek, which is the most seen since 2006. These salmon probably weren’t born in Lagunitas Creek but may have gotten lost as they tried to migrate back to their natal streams in the Central Valley.
One of the most perplexing aspects of our Chinook observations this season has been the presence of very small salmon (less than a foot long) sharing redds with very large Chinook. These small fish behave like “jacks,” which are small but sexually mature salmon that return to spawn a year earlier than full-sized salmon. The adult male salmon chase the jacks like they were competitors, but we’ve never seen jacks this small. We’ve only seen two so far, but ruled out trout or other fish species as candidates. A little research turned up a Chinook life history variant called the “mini-jack,” which migrate as fry to estuaries for only a couple of months before swimming back upstream to spawn. If these little fish are indeed mini-jacks, then Chinook salmon must have spawned in Lagunitas Creek last year without being observed. We did find a few redds in October and November last year that looked like Chinook redds, but without seeing the fish we couldn’t assume that Chinook had returned. Now it looks like the King may have returned a year ago.
To date we haven’t seen any coho salmon in Lagunitas Creek, but that’s not unusual. The first coho tend to show up in late November after heavy rains increase stream flows. Last week’s rain hardly increased flows, so the coho may be waiting a little longer to migrate upstream. Rain or no rain, we’ll probably start seeing coho within the next couple of weeks. Once the rain really starts falling, we’re expecting more coho salmon to return to Lagunitas Creek than we’ve seen in at least seven years.