Dams are one of the biggest problems for fish that undertake migrations, like salmon. If a big wall blocks the route to breeding or feeding grounds, that can spell doom for the fish. And the existing mitigation measures, such as fish ladders, aren't very effective solutions.
Enter the salmon cannon. As ridiculous as it sounds, one group of entrepreneurs from a company called Whooshh Innovations thinks that shooting fish down a tube and then firing them into the air could be a solution for helping fish like salmon overcome migration barriers. CNET explains the salmon cannon's methodology:
It works a little like a pneumatic tube. Fish go in one end, and the soft fabric of the tube forms a seal around the body of the fish, creating a vacuum, which in turn propels the fish through the tube at a speed of around 5 metres to 10 metres per second (11 mph to 22 mph).
The tube was originally designed for transporting fruit, but based on successful results from initial tests, CNET continues, the design work just as well on live fish. The salmon don't seem to mind the experience, either. If given the opportunity, CNET writes, the fish will swim into the tube themselves, and when they emerge on the other side, they go about their business as if they hadn't just been fired through the air at 22 mph.