Whooshh Innovations' "fish gun" shoots salmon over obstacles small and tall
By David Szondy
August 21, 2014
If you live in an area where salmon spawn, then summer treats you to a free nature drama as the fish battle against currents, fight through rapids, struggle up tiny streams, and leap up waterfalls to return to the calm pools where they were born. Unfortunately, however intrepid the odd salmon is, they weren't built to take on a 300-ft tall hydroelectric dam. That's why Whooshh Innovations has developed a system that sucks the fish up through a plastic tube and shoots them over obstacles low and tall like so many piscatorial projectiles.
For over a hundred years, engineers have helped salmon and other migratory fish around insurmountable man-made barriers, such as dams, locks, and weirs, by installing devices to help them get around the structures. Some dams have fish ladders that allow the migrants to jump from one artificial pool to the next in a series of steps. Others have fish lifts, which raise the salmon to higher water in batches; locks that lift them like passing boats; and even lorries that take the netted fish by road to the next stage in their journey.
The problem with most of these solutions is that they are expensive, can take as long to install as it does to build the dam, can’t be moved once in, and can stress the fish. The solution developed by Whoosh Innovations from Bellevue, Washington is designed to avoid these setbacks by means of a portable system that can be quickly set up either temporarily or permanently, costs much less than conventional methods, yet can move large volumes of fish over the highest of obstacles.
The Whooshh Transport System is basically a flexible plastic tube hooked up to a motorized air pump. As the fish swim upstream, they’re led to a collection point that’s similar to the kind of false weir or water step used on a fish ladder. The fish are attracted to the water flowing over the weir and jump it, but instead of landing in a pool of water, they hit a slide and slip to the breach of tube, where the lower air pressure inside sucks them in and up the tube. A pressure difference of about 2 PSI with a mist of water acting as lubricant shoots the fish along at 5 to 10 m/sec (16 to 32 ft/sec), and once at the top, they pop through a gate and into the water after a brief flight through the air.
According to Whooshh, the system can handle fish of over 15 kg (33 lb) at a rate of 40 per minute, and that it doesn't damage the fish’s scales or eyes – though it may surprise them. Because the system uses air rather than water pressure, the company says there’s no theoretical limit to the height it can reach. It has only three moving parts, consumes 5 to 25 kW of power, and the 34 L (9 gal) of water per hour used for lubricant won’t freeze significantly, so the transporter can be used all year round.
In addition to being quick to set up and take down, Whooshh says that the system reduces fish lingering that plagues fish ladders, and because the tube shoots one fish through at a time, it’s ideal for screening fish to identify whether the fish are wild, hatchery, or escaped farmed varieties.
The video below shows the Whoosh Transport System in action.