Return of the Little Red Fish

By Aki Alonzo, Marine Biology and EEC Biology ‘25

Spawning kokanee in Lewis Creek, Bellevue, WA (Image credit: Roger Tabor, USFWS, 2024).

In the mid-20th century, Lake Washington and Lake Sammamish both teemed with tens of thousands of kokanee salmon. Today, kokanee are known only within Lake Sammamish, having dwindled to less than 5% of their historical abundance in recent decades. An alarmingly low run for the 2017-2018 season prompted King County executives to declare a state of emergency for the population. But what pushed kokanee so close to the edge? What recovery efforts were made these last six years, and what does the future look like for the little red fish?

Urbanization of the Lake Washington and Lake Sammamish watershed is a major factor of decline for the kokanee population. Since 1860, King County’s population has ballooned in size from a few hundred to nearly 2.3 million people, drastically altering and polluting the watershed. Streams and riparian areas have been developed for human use, leading to the loss of food, shelter, and migratory channels needed to support a robust kokanee population.

On top of habitat degradation, kokanee face what scientists call a “temperature-oxygen squeeze” – a summertime shrinking of the water column region hospitable to juvenile kokanee. As average surface water temperatures increase with climate change, young kokanee dive deeper to beat the heat, where they risk suffocation under low-oxygen conditions. By crowding into an increasingly small habitat, they are hypothesized to become more vulnerable to predators and have difficulty finding food.

After less than 20 kokanee returned to spawn in the winter of 2017-2018, King County executives issued an emergency order to mobilize the Lake Sammamish Kokanee Work Group. Formed in 2007, this task force joins numerous agencies and communities, including the Snoqualmie Tribe, in the goal of kokanee recovery. Through hatchery supplementation programs, the group ensures that thousands of healthy young kokanee are released into the watershed each year. Members of the group also engage in numerous projects to restore kokanee habitat, replacing culvert pipes with modern box culverts and planting native vegetation.

This past winter, the group’s efforts were rewarded with a record-size run of over 8,100 adult kokanee – the largest in a decade. Experts say this development is a result of culvert modernization in addition to well-researched, controlled kokanee rearing.

It remains to be seen whether the kokanee population, under modern conditions, can return to its historical abundance. But for now, the little red fish seems to be back from the brink.