by Bob Flasher
The SF Chronicle front-page headline of 1/26 reads “Crisis for the coho.” It begins, “The lack of rain this winter could eventually be disastrous for thirsty California, but the drought may have already ravaged some of the most storied salmon runs on the West Coast. The coho salmon of Central California, which swim up the rivers and creeks during the first winter rains, are stranded in the ocean waiting for the surge of water that signals the beginning of their annual migration, but it may never come. All the creeks between the Golden Gate and Monterey Bay are blocked by sand bars because of the lack of rain, making it impossible for the masses of salmon to reach their native streams and create the next generation of coho. The endangered coho could go extinct over much of their range…”
This is a shocking reminder that it is extremes, not averages, that have the most impact on all wildlife populations. The impact of the spawning failure goes way beyond the salmon populations. All the predators that depend on the annual salmon runs will go hungry. All the forests that depend on the nutrients from remains of salmon after they are eaten, will lack the normal recharge of nitrogen they need for vigorous growth. The dearth of decaying post-spawning salmon in the streams will negatively impact the availability of nutrients that macro-invertebrates need to complete their life cycle. This lowers the amount of food available for whatever other fish live in the creeks, such as steelhead trout that haven’t yet made it to the sea. As John Muir pointed out, “If you try to pick out anything by itself, you find it hitched to everything else in the universe.”
The good news is that coho salmon populations in the Pacific Northwest are still going strong. And the populations of their relatives, the steelhead and rainbow trout, like the ones we hatch in our classrooms, are still healthy. In future years, when rainier times return to California, there is some hope that the more directionally challenged coho will spawn up the streams that are now inaccessible, restoring the former populations. But even if streams are repopulated, some genetic diversity will have been lost in the process. And genetic diversity is what helps keep populations adaptable to changing conditions.
The Aquatic Project Wild activity that captures the impacts of this variability of available habitat is Migration Headache. The scenarios in the activity are focused on bird migrations, but can be adapted to trout in streams and lakes. Our trout diet poster and the watershed slideshow in our WILD About Trout CD can help you come up with ideas for trout-related consequences in this interactive outdoor educational game.