Scientist working on White Salmon River screw trap
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.