The 'salmon cannon' that shoots fish over dams

You've got to wonder how some ideas are born – let alone ever end up working. You have to suspect a certain amount of beer is involved in the gestation of some. Like the one that ended with a guy saying, "You know what we need. A cannon hundreds of feet long that will shoot fish over a dam..."

And yet Todd Deligan went off and did just that. As he told The Verge...

So we put a tilapia in the fruit tube. It went flying, and we were like, ‘Huh, check that out.'

Deligan is vice president of the aptly named Whooshh Innovations which started out in the business of transporting delicate produce, like ripe tomatoes, using vacuum pressure tubes. So it wasn't perhaps such a stretch to get to "so what would happen if we put a fish in it?".

But the crazy idea has a practical purpose – to help salmon, blocked from travelling up river to their spawning grounds, get over the dams that stand in their way.

Traditionally, the problem has been solved using fish ladders – a series of stepped pools – but that has limits and very high dams remain impassable.

The Whooshh system uses vacuum pressure to propel the fish along a track at up to 35 kph. The track is kept wet to smooth the way.

Even more clever is the design that sees the fish load themselves into the system through a weir that they naturally jump into in a bid to get upstream. Instead they end up in the "breech" of the cannon.

Whooshh says they can transport up to 40 fish of up to 15 kg each per minute and to virtually any height.

Because we do not have to move a column of water, we have no theoretical limit. There may be practical limits, but if we have not encountered such project yet.

There's a company video of the whole process below.

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