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/
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