Fish Cannon - Worth Shooting?

By Rena Ruusuvuori

When we think about energy production, the cleanest and most environmentally friendly options are generally associated with those generating energy from wind and water: renewable sources (see previous post about hydropower!). However, despite the positive image, hydro plants and dams associated with them do cause a lot of negative impacts on river habitats. In this blog post I will concentrate on those poor fish populations which find a dam wall straight up their fish-faces; and one fresh, splendid innovation to help them break through. 

For river habitats, the problem with dams is that once it has been built, it effectively blocks fish species from migrating and getting back to their spawning grounds. It has been estimated that some 42,000 large dams, defined as more than 15m high, have existed globally since 1996, not to mention 800,00 smaller ones. Anadromous species – that is, those species that are born in freshwater migrate to the sea and return to their birthplace to spawn – have suffered serious losses in terms of declining populations and even local extinction. Up till now, several options have been developed in order to help our slippery friends to travel upriver: pool-type passes, fish lifts, nature-emulating passes and so on. Problems with the passes are plentiful; they need maintenance; it is difficult to emulate just the right hydraulic conditions, and provide stimuli to guide the fishes to find the pathways provided.

A new player in the field, fish cannon, will operate by creating gentle suction in a flexible tube once the traveler has braved itself into entering the passage of its own accord (otherwise known as volitional entry). However, as delightfully absurd as this concept is, it might be worth a shot. The system is currently going through testing to ensure the well-being of cannoned fishes in the long term. Benefits of this type of a fish pass would be considerable according to the company behind it: lower maintenance and building costs, no dam wall height restrictions and volitional entry for fishes just to name few.

Despite the rather good start in the innovation field, more options need to be developed and implemented. Relevant biological information on matters such as species travelling down the river for migration and spawning purposes need to be taken into account as well, not forgetting research on each species involved in the river ecosystems. Aside from mating and reproducing intentions these fishes don’t struggle upstream just for fun; as they end up as food for hungry bears and they also graciously donate nutrients for trees and other flora. To conclude: better a fish eaten upriver than ten sitting below dam.

SOURCES: 

http://www.esf.edu/efb/limburg/watershedecology/readings/freeman-dams.pdf      http://www.internationalrivers.org/environmental-impacts-of-dams

http://whooshh.com/economics4.html

 http://www.fao.org/3/a-y2785e/y2785e03.htm  

 http://thefisheriesblog.com/2013/05/20/can-you-say-anadromous-catadromous-amphidromous-oceanodromous-or-potamodromous/