Coho salmon (Onchorynchus kisutch) may be the overshadowed cousin of “king” Chinook in California, but are certainly deserving of some time in the spotlight. Like Chinook, coho face an array of challenges in the form of habitat loss and human-caused changes to their home rivers. However, unlike Chinook, which have had their populations boosted by billions of hatchery-produced fish, coho have not been stocked en masse, and their populations have experienced precipitous declines. As a result, the group of Central California Coast coho known as an Evolutionarily Significant Unit (ESU) were listed as Threatened under the Endangered Species Act in 1996, and this listing was upgraded to Endangered in 2005. Fortunately, there are efforts underway in Scott Creek, located just north of the city of Santa Cruz, to help restore a critical population of this coho ESU with the help of a conservation hatchery.

 

Winding its way among the redwood-shaded valleys of the Coastal Range, down through sand dunes and into the Pacific Ocean, Scott Creek has a watershed of only 30 square miles, yet contains 13.9 miles of potential salmon habitat. Though small, this coastal stream nevertheless hosts important populations of both coho salmon and steelhead (Oncorhynchus mykiss). Since 2001, a collaborative program between the National Oceanic and Atmospheric Association (NOAA) and the Monterey Bay Salmon and Trout Project (MBSTP) has operated a conservation hatchery for coho on Big Creek, a tributary of Scott Creek. Adult coho returning from the ocean to spawn in the watershed are collected and brought to the hatchery, where their DNA is collected and analyzed. Using this information, the hatchery personnel act as matchmakers and select spawning pairs of coho to both maximize genetic diversity and prevent inbreeding. The hatchery is capable of producing as many as 35,000 coho smolts; if 2% of these survived to adulthood, an expected 700 would return as adults, which is believed to be the maximum population the watershed could support. However, ocean survival is often lower than 2%, and adult returns are significantly beneath this maximum. A stable adult return of 255 individuals is NOAA’s goal for down-listing the population to threatened, and a stable return of 510 individuals is the target for population recovery. Numbers of coho returning to Scott Creek have typically ranged from just five to 30 fish since 2007, underscoring the need for a helping hand.