Science - November 4, 2009

Fish farming more sustainable thanks to animal experiments

Wageningen University used twice as many fish in 2008. Experiments showed that fish farming can be less polluting by using less water.

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Wageningen University used ten thousand fish last year, but there is little sign of that in the Fish Experimental Station behind the Zodiac building. It is true, you do hear the constant sound of running water and yes, it really does smell of fish. But there can't be more than a couple of hundred tilapias, catfish and carp swimming around. Most of the dozens of tanks are empty.
There were three major fish projects in 2007 and 2008: two for the EU and one for the Ministry of Agriculture. They finished in 2008 and were therefore included in that year's laboratory animal statistics.
The creatures did not suffer any pain. The fish (catfish, tilapia, turbot, sole and eel) were weighed twice. At the end they were killed using an overdose of TMS, a fish anaesthetic. Even so, the researcher does not want his name in the papers; animal activists smashed windows in the Zodiac building next door earlier this year.
The anonymous researcher at the Aquaculture and Fisheries Group explains that the fish were used for research into a sustainable form of fish farming, the recirculation system. This system has two advantages: it doesn't use much water and it hardly produces any waste products.
'It consists of an aquarium for the fish and separate areas for water purification and the collection of fish excrement. The fish excrete ammonia, which is poisonous. Bacteria convert it into nitrate and then into nitrogen gas.'
This makes tilapia farming a lot more sustainable, as one of the EU projects showed. 'In our experiments the amount of waste fell to 50 cubic metres of solid waste per 100,000 tilapias per annum. And our water consumption was 40 litres per kilogramme of fish. The usual method, where you refresh the water, uses 200 to 300 litres per kilogramme of fish.'
The reason so many fish were required is because the experimental unit is the tank, explains animal experiments expert Rob Steenmans. 'You need several experimental units - so several tanks - for a reliable experiment. And each tank has dozens of fish swimming in it.'
More laboratory animals
Nationally, the number of experiments with laboratory animals fell by three percent to 578,123. That is the figure in the annual laboratory animal report by the Food and Consumer Product Safety Authority at the Ministry of Health, Welfare and Sport. However, there was actually a big increase in the number of animal experiments at Wageningen University, from 11,963 in 2007 to 16,972 in 2008. DLO institutes such as ASG in Lelystad do not disclose the number of animal experiments they carry out. The increase in Wageningen is due to the fish studies: five thousand fish were used in 2007 and nearly ten thousand last year. Wageningen scientists also experimented on 3884 chickens, 1132 mice and 936 pigs. Nearly one thousand animals were used in teaching.

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