A fish passage study on American shad.
![A fish passage study on American shad.](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/thumbnails/image/Photo%203a.jpg?itok=peZ6MKxJ)
Detailed Description
While these gates might look similar to the entry way of a medieval castle, they are actually part of a scientific experiment that will help scientists design more effective fish passage structures for American Shad. Photo by Kevin Mulligan, USGS.
Sources/Usage
Public Domain.