Comment by chihuahua
11 hours ago
There is similar work going on to restore fish passage underneath I-90 near Issaquah, Washington. Although in that case, the part of the streams that's currently inaccessible is less than a mile for most of them, and 2 miles for one of them. It's a major undertaking to restore a stream bed or channel underneath the interstate.
This will benefit Kokanee Salmon, a kind of salmon that spends all its life in fresh water and does not migrate to salt water like most salmon.
In Lewis Creek, they currently have access to only 1/2 mile of the creek, but in 2021 there were about 1000 of them returning (from Lake Sammamish) to spawn.
That's really surprising that they could survive with such a small range! How are they counted during their migration?
There are traditional methods like electrofishing and tagging. But there are also non-invasive methods such as environmental DNA where you can detect organism prevalence from DNA shed into the ecosystem. Our platform was built specifically to help share that type of science for restoration and remediation projects: https://www.ednaexplorer.org
There's an organization of volunteers who walk the streambed during spawning season and mark nests with colored tape on nearby branches. I assume while they're doing that, they also count the fish somehow? They also put a trap near the end of the stream at certain times of the year and count the fish in the trap - the fish are obviously released from the trap afterwards.