Cedar River Salmon Journey
By Tararin N.
Back in October members of the Puget Sound: We Love You campaign took a field trip to the Cedar River to discover thousands of brightly colored sockeye salmon (and a few Chinooks!). In the chilly wind we chatted with volunteer naturalists at several sites along the river, and learned lots about salmon and conservation.
Let’s start with some simple facts about the sockeye salmon (Oncorhynchus nerka). Their average adult length is 24 inches (about 60 centimeters). During their migration and mating season, they change from shiny silver to bright red with a green head. You can tell the difference between males and females based on their coloration. Males are much more brightly colored, while females have a more neutral brown color. In the fall, sockeye return from the ocean to rivers and streams, generally where they were spawned. Shortly after a pair has met to lay and fertilize their eggs, both adults will die.
Although salmon lay about 3000 eggs, only about 300 survive to become fry (young between 5 and 10 weeks of age). Only about 50 are likely to become smolts (juveniles 1-3 years old), and only four ever reach adulthood. Of the adult population living at sea, only half will successfully return to their spawning ground. Each adult mating pair will have only two offspring survive long enough to reproduce in turn. All of these dying salmon are not useless, however.
Salmon eggs and young are an excellent food source for animals in spawning streams, and juveniles are a popular snack among larger marine predators. The bodies of spawning adult salmon serve as nutrition for animals, soil, and plants along the riverbanks. As they decompose and are eaten by scavengers, they return valuable nutrients from the sea back to the land. Living salmon can be devoured by hungry predators as well, including bears, eagles, and humans.
At one of the sites we visited, we observed a weir set up by the Washington Department of Fish and Wildlife (WDFW). A weir is a sort of gate; it is an enclosure of stakes set up in the river to direct and trap fish. At this site, the naturalists told us that the weir was cleared out a couple of times a day, allowing the workers to take up to a thousand salmon per day to the hatchery. The hatchery is operated jointly by Seattle Public Utilities and WDFW.
Human-related factors such as commercial and recreational fishing, aquaculture, dams and dikes, forestry operations, hatcheries, farming and ranching, mining operations, urban and suburban development, and invasive species can all affect salmon greatly. We can all do simple things to help salmon. Gardeners can use compost instead of artificial fertilizers, and use native plants to discourage pests. Washing cars at commercial car washes, instead of in the street where runoff can get into streams, helps. We can recycle motor oil, frequently check our cars for leaks, and drive less in general. We can restore stream and river banks by removing invasive vegetation and replacing it with native trees and shrubs. This helps control runoff and prevent erosion, which keeps streams cleaner. By taking a few simple actions, each of us can help protect salmon for years to come!