Salmon have interesting migration and reproduction habits.
They're born upstream in rivers, in gravel beds. They spend most of their developmental years in those rivers, but by adulthood, the fish swim downstream, making their way to the ocean.
While swimming in the Atlantic or Pacific, these adult salmon eat and swim until its time to spawn.
At that point, the fish head back to the rivers (often the river from which they came) and swim upstream until they reach the gravel bed, start the next generation of salmon, and die.
Ecologically, this return to the river is important — the deceased fish brings vital nutrients from the ocean back upstream, and in most other cases, those nutrients wouldn't ever find their way there.
Unfortunately, humans have a tendency to get in the way: We build dams, holding back rivers and blocking the path of the spawning fish.
We've come up with some workarounds, the most common being fish ladders, which run alongside dams, allowing fish to swim upstream (Wikipedia's explanation has a lot of great pictures).
But those ladders are expensive and often take a long time to build.
Researchers are looking for other solutions ... such as shooting fish out of a cannon.
OK, it's not really a cannon — it's more akin to a pneumatic tube, to be fair. But “salmon cannon" sounds much better, right?
The cannon was created by “Whooshh Innovations," a Washington-based company dedicated to using such methods of transportation in various new contexts.
Transporting fish above dams seemed like a good use, so they built a set of prototypes. Here'a video of the cannon in action — the GIF above comes from it.
As seen in the video, the fish (the cannon isn't limited to salmon) enter the tube single-file and, during their trip, are in an air environment, but no matter, within a few seconds, they're returned to the water.
In most of the examples shown, the fish are loaded into the tube by a worker, although in many cases that's not required. In situations where it is, that still may be OK — in addition to fish ladders, another conventional solutions to the fish migration problem is called “carry-run-toss" (it's shown at 2:05 in the video), and that's a lot more labor intensive.
The carry-run-toss method literally involves a person ... running up a flight of stairs and ramps and tossing the fish into the water at the top of the dam. This is a real job.
(If you can't watch the video, the carry-run-toss method literally involves a person taking the fish from a tank, running up a flight of stairs and ramps, and tossing the fish into the water at the top of the dam. This is a real job.)
The salmon cannon can transport fish up to 250 feet (with a 100 foot incline) at speeds approaching 22 miles per hour — that's about an eight-second trip for the fish.
Mental Floss reports that the tubes can transport 40 fish per minute, which is apparently a lot.
It is still highly experimental, but it has promise: Officials are already testing it out in hopes that it works.