A big thanks to all of our volunteers who participated in the 2016-2017 Coho and Steelhead Spawner Surveys! Through your dedication and flexibility, we were able to successfully complete all of our spawner surveys.
2016-2017 Spawner Season Summary
Coho salmon are three years old when they return to their natal stream to spawn. These spawners are the offspring of coho that spawned three years prior, and the parents of the generation that will spawn in another three years. As a result, there are three distinct year classes, or cohorts, of coho salmon spawners in each creek, each with its own population trends that may only be tracked every third year. The 2016-2017 spawner cohort is primarily descended from coho that spawned in the winter of 2013-2014.
This winter, Marin County saw its wettest January in over 20 years—the seventh wettest since record keeping began in 1880. Although crews were unable to survey as often as in past winters due to the heavy storm events, we observed more than double the number of coho redds (nests) on Redwood Creek compared to the winter of 2013-2014. The number of redds on Cheda Creek stayed the same, and we counted 35% fewer redds on Olema Creek compared to the previous generation of this cohort. However, given the storm pattern and stream conditions in December and January, it is possible that some redds were not detected. It can take over a week after a large storm event for creeks to return to optimal survey conditions. Large storms can also leave redds indiscernible from other areas of the stream bed. We will use juvenile surveys performed in the summer of 2017 in Olema, Pine Gulch, and Redwood Creeks to validate the spawner counts and indicate if redd under-detection was likely.