As if migrating salmon didn’t have a hard enough journey already, when they meet a hydroelectric dam they are well and truly stopped in their tracks. Fortunately the owners of these dams are required to provide some kind of fish pass (sometimes called a fish ladder), which is a man-made structure constructed on or around such dams (or other similar barriers), through which the migrating fish can pass.
According to Wikipedia, evidence of fish passes dates to “17th-century France, where bundles of branches were used to create steps in steep channels to bypass obstructions.” Other versions were later developed in Canada, Ireland and the USA – with each design becoming more robust and permanent than the next – predominantly because the obstacles themselves were becoming larger and more difficult to pass.
The term fish ladder is perhaps the best clue to how most of these fish passes work: river water is diverted down a series of relatively low steps, which are low enough for the running fish to leap over, but which provide enough flow to attract the fish to the ladder in the first place. These ladders are very similar to the waterfalls and pools that the migrating fish have to navigate in the wild.
Unfortunately for the fish, some dams are simply too large or too high for fish passes to be practical or effective, which has led designers to look for a new solution.
In steps Seattle-based company, Whooshh Innovations – a company specialising in moving live or highly perishable food products from Point A to Point B. Having already developed vacuum-based technology for transporting delicate food products, the people behind Whooshh believe they have found a way to solve the fish pass problem – namely, the salmon cannon.
As Whooshh’s Vice President, Todd Deligan, told The Verge:
“We put a tilapia in the fruit tube… It went flying, and we were like, ‘Huh, check that out.'”
Having spent years perfecting the design using frozen fish as cannon fodder, Whooshh nows says it has a system that allows migrating fish to enter automatically, before being boosted along a constantly lubricated tube, powered by vacuum pressure, at speeds of between 15 and 22 mph.
The Verge reports that live Chinook salmon have already been through the system successfully and the US Department of Energy will oversee a further test in September.
Check out Whoosh’s video here:
Article spotted at IFL Science
Original article by The Verge
Fish ladder info from Wikipedia