Coho Salmon Reintroduction

I just got back from a camping trip with my fourth graders in the redwoods of northern California.  One of the highlights of the trip for them and me was that we got to participate in the release of some Coho salmon back into one of the many small creeks in this area.  These salmon were part of a special program by a coalition of groups interested in restoring natural habitats, including governmental, local, and ecology groups.  

These streams used to be full of Coho salmon and then they began disappearing following a misguided effort to “help” the environment.  Water management staff removed the root wads, old logs, and the natural accumulation of woody debris from the creeks and streams, as well as clearing overhanging branches.  This practice depleted the natural pools of water the Coho used for spawning, got rid of the natural cover they used to hide from predators, and the direct sun on the water raised the water temperature above the 60 degrees Fahrenheit needed by the Coho to survive. 

As the salmon vanished, people realized their mistakes and began restoring the woodland creeks to their natural state and developed a program to reintroduce the Coho.  One part of this project was to imprint the Coho smolts that were released on this creek.  Coho salmon hatch in these creeks and spend up to a year in these waters as they develop.  They then swim to the ocean where they typical spend about four years.  Finally, they swim back up stream to the same place they were hatched to spawn.   While we don’t fully understand how they find their homes, we know that the scent of the water and other chemical cues are important. 

We arrived in time to help release a group of smolts that had spent three weeks in a tank of fresh Dutch Bill Creek water imprinting on the bio-chemical cues that will help them find their way back to spawn here in four years or so.  We helped scoop the smolts from the tanks into buckets and formed a bucket brigade to the creek.  After the release, we watched at the salmon smolts began to explore their new home.  Many of my students named this as their most memorable event in a week filled with nature and personal adventures.