Spawning Salmon

by Barbara May and Cynthia Stockwell

Imagine a series of terraced pools, crystalline cold, McKenzie River water teeming with huge salmon, cheek to cheek, fin to fin, jostling each other, biting each other, anxious to culminate their 326-mile journey up the Columbia, then the Willamette, then the McKenzie, finally arriving at their birthplace, the upper McKenzie just downstream of Trail Bridge Dam.

Jeff Ziller, regional biologist for the Oregon Department of Fish and Wildlife, accompanied by his wife Anne, herself a naturalist, outdoorswoman and illustrator, led an awestruck group of LCAS Auduboners to this site where we watched upwards of 80 of these beautiful, noble fish spawning, hoping to replace themselves with a new generation of magnificent Chinook. The fish we saw were huge, many of them three feet long and scuffed up, injured by their four-year ocean life and their long arduous trip from the Pacific. Still, they were full of energy and enthusiastically making use of the spawning channel created for them after construction of Trail Bridge Dam in the 1960s. The series of six pools in the channel was created to perfectly match salmon preferences for gravel size, water temperature, stream velocity and other variables. Despite all of this, until recently only a dozen or so had returned to the channel each year to spawn, frustrating scientists.

The exciting bounty we were observing may have been the result of a new strategy, first employed by Jeff in 1997: he released hatchery fish in Trail Bridge Reservoir, above the dam. This seems to have increased their drive to swim farther upriver into the spawning channel.

For all of us, it was a treat to spend time with an expert who could answer all of our questions about these amazing fish. Jeff showed us how to identify redds (spawning beds) by the distinctive lighter color of the gravel. We learned that only 2 in 4000 of the eggs laid here will survive to return as an adult Chinook. In fact, about 5% of salmon travel up the wrong stream on their return from the ocean, a phenomenon that helps to reestablish runs after ecological disasters. We also learned that when salmon die after spawning, their decaying bodies fertilize the ecosystem to support the next generation of salmon. Once again, we learned, everything is interconnected.