Scientist working on White Salmon River screw trap
![Scientist working on White Salmon River screw trap](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/media/images/Jill%20Hardiman%20working%20on%20White%20Salmon%20screw%20trap%20-%20Ian%20Jezorek%20CRRL.jpg?itok=yZ6Uu4gZ)
Detailed Description
USGS scientist, Jill Hardiman, working on a screw trap on the White Salmon River to assess anadromous fish recolonization following removal of a large dam.
A screw trap consists of a large cone suspended between two floating pontoons. River flow rotates the cone and funnels a portion of the migrating fish into an underwater holding tank at the back of the trap. Fish are sampled, data recorded, and then released.
Sources/Usage
Public Domain.