Land-based fish farms are environmentally Preposterous

December 5, 2003

Land-based fish farms are environmentally Preposterous

The David Suzuki Foundation, Greenpeace and a host of activist groups claim that salmon farms are bad for the marine environment. Their solution is to demand that fish farms be located in tanks on land instead of the current practice of growing salmon in nets in the sea.

An obvious - if flippant - response to this idea is that it makes as much sense as to demand that cows and pigs be farmed in the ocean in order to save the land. But there is a more serious side to the argument against raising salmon on land.

Salmon need seawater to live and grow. If they are put in tanks on land, it becomes necessary to pump sufficient seawater up into the tanks to keep the fish alive and healthy. In particular, salmon need the oxygen that is dissolved in sea¬water. If the seawater is not continually renewed, all the fish will die in a matter of hours.

Pumping water uses energy, a lot of energy. Most salmon farms are in remote locations where there is no renewable hydro-electric power, so diesel-powered pumps are the only practical way of delivering seawater to the tanks.

A simple calculation reveals that pumping seawater would take 3.6 litres of diesel oil to produce one kilogram of salmon. This works out to about 252 million litres of diesel at an energy cost alone of $200 mil¬lion to produce the 70,000 tonnes of farmed salmon grown in B.C. in 2002. The wholesale value of that salmon is $290 million. So not only is the land-based solution impossible on an economic basis, it is environmentally prepos¬terous. Imagine environmental groups proposing a solution that results in a massive increase in fos¬sil fuel consumption and harmful greenhouse gas emissions associat¬ed with burning diesel oil.

The additional fossil fuel required, to grow salmon on land in B.C. is equivalent to providing the total energy requirements for a commu¬nity of more than 33,000 people. This is hardly a prescription for compliance with the Kyoto Proto

When salmon are grown in nets in the sea, they should always be placed where there is a good tidal current. The tides bring fresh sea¬water with oxygen and the tides carry away the nutrients from fish waste to fertilize the surrounding area. It is no secret that prawns, crabs and other marine species are abundant in the vicinity of salmon farms.
The tides that deliver oxygen and disperse nutrients from salmon farms are driven by the gravity of the moon and sun. Tides are renewable and sustainable; diesel fuel is non-renewable and -results in green¬house gas emissions that may cause climate change.

Yet in their wisdom -the anti-¬salmon farming activists propose a "solution" that is really just a thinly disguised tactic that would make salmon farming economically impossible and environmentally unfriendly.

Patrick Moore was a co-founder of Green peace and was president of the B.C. Salmon Farmers' Association tom 1986 to 1989. He is chairman and chief scientist of Greenspirit Strategies environmental consultancy to government and industry