Eric,

Remember those old department stores where they put cash and checks into a cylinder, stuck it in a vacuum tube, and it whooshed away to the upstairs accounting department? It's sorta' like that. The fish is placed in the cylinder that seals shut around the fish; then the cylinder goes whoosh, through the vacuum tube to its destination.

We don't know if these have real world practical applications for fish passage. My hydraulics engineer office mate has been reviewing and working with this part of the past year. Time will tell.

Sg