By Thijs Westerbeek van Eerten
http://www.radionetherlands.nl

Fish farms often have a disastrous effect on the environment, but that need not be the case. The idea behind farming fish for consumption is, in itself, environmentally friendly and could mean that the world's oceans are not plundered, and also help keep the disruption of the world's ecologically-vulnerable seabeds to a minimum.

The current approach to fish farming is harmful, however. Trout and salmon farms in Scotland and Norway constitute an industry in their own right and consume massive amounts of energy. Maren Esmark, of the Norwegian branch of the Worldwide Fund for Nature (WWF) explains:

"It takes three or four kilos of wild fish to obtain one kilo of farmed salmon. So it is important to realise that salmon farming is an inefficient way of producing food. It involves taking enormous amounts of food out of the ocean, food that is perfectly suitable for human consumption, and turning it into a much smaller amount of salmon... "Nowadays Norway is hard at work to develop more environmentally-friendly methods of farming fish. Scientists are starting to produce fishfood that is partly or wholly plant-based. Another solution is to produce nutrient-rich fishfood so that only smaller amounts are needed. The Norwegian researchers seem to be on the road to success, but they are not there yet.

The great escape
Another major problem with salmon farms in the Scottish lochs and the Norwegian fjords is the large number of farmed salmon that escape. These fish push the wild salmon out of their natural environment and often spread disease among the wild population. Maren Esmark of the Norwegian branch of WWF describes the scale of the catastrophe:

"Between half a million and one million farmed salmon escape in Norway each year. And we know that the total population of wild salmon is only around half a million! So there are already more escaped salmon than wild salmon swimming in our rivers and fjords!"

Environmentally friendly
But fish farming need not result in environmental disaster. Many types of fish grow perfectly well in closed-off basins on land. This means that there is no danger of the farmed fish interfering with the wild population, and these basins are out of reach of diseases. Even if disease were to strike, this approach would prevent the wild fish from becoming infected.

It is also possible to select types of fish that provide much more food while consuming less. The catfish, for example, originally an African freshwater fish, provides one kilo of fish for every 800 grams of food it consumes. The rest of its growth comes from the warmth of the water in which it swims and the air it breathes. The catfish is a lungfish.

A working example
Until a few years ago, Hans Herpers was a pig farmer in the Dutch village of Vredepeel in rural Limburg, not far from the town of Venray. But after the last outbreak of swine fever he abandoned livestock and started a catfish farm, working on environmentally-friendly principles:

"We operate a recirculation system, which means that we use very little water. We re-use the same water which is cleaned on an ongoing basis by special bacteria. That also means we use less energy, because we don't have to keep heating new water. The water is pumped to a bioreactor, where the bacteria combine with oxygen to break down the waste products."

The food the fish are given at Herpers' catfish farm is also measured with the utmost precision. This prevents all kinds of fish diseases and stops water pollution. In addition, the former pig farmer is busy looking for an environmentally-friendly way to process the algae that inevitably grow in the basins. He thinks he might be able to burn it as biomass to produce energy or possibly even process it into feed for animals or indeed fish!

It is interesting to note that Hans Herpers is not taking this ecological approach out of concern for the environment. That may be a positive side effect, but as a businessman his main concern is his profit margin, and it so happens that all of the environmental measures he works so hard on are also financially attractive. It was an uphill battle to start with, but now his catfish farm is a sound business proposition. Hans Herpers knows why: "The fish are tasty! That's all there is to it!"