Surprises at start of spawning season

11/30/2017

Marin Municipal Water District was halfway through a two-year project to improve floodplain in lower Lagunitas Creek on Aug. 22 when it was treated to a surprise: a rare chum salmon swimming through a channel that had just been excavated. 

It was the first time the district has spotted salmon before October. Chum have been seen in the creek before, though they are more commonly found in Oregon and Washington and it’s coho and chinook that are most typical in Lagunitas Creek. 

Then, during a survey last month, the district counted 10 pink, or “humpback,” salmon, which are uncommon south of Washington State. 

“As a biologist, anytime I see something that I haven’t seen before is a good day,” Eric Ettlinger, an aquatic ecologist for the district, said. “We’ve now seen four of the five Pacific salmon species in one season, which is incredibly rare. To get all of these species at the very beginning of the season is both exciting and weird.” 

Mr. Ettlinger said he’s heard that ocean feeding in the Pacific Northwest has been poor this year, so it’s possible these fish came afar in search of better foraging. “But it’s difficult to assign a trend to this,” he said. “The poor ocean conditions in the Pacific Northwest have been attributed to climate change, although it’s very difficult to know for sure what is causing the poor productivity in the ocean. One of the things we’d expect from climate change is for the salmon species to move north because we’re at the southern limit of where they can tolerate temperatures in the streams.” 

With the district and the Salmon Protection and Watershed Network restoring floodplain and fish habitat in the creek, the unexpected arrival of the salmonids indicates their efforts will benefit more species. “For years, I’ve said that the most important reason to conserve salmon in this urbanized area is that they are incredible educators,” Mr. Ettlinger said. “The salmon teach us about water conservation, pollution, climate change, food web conditions in fresh and saltwater, erosion. You can bring so many areas of science and conservation into the salmon life cycle and, in an urbanized area like this, we need that kind of teacher.”