3 November 1999

Piscatorial Weight Watchers?

by Kate Melville

People in Western countries say they are eating less meat and fat and more vegetables and fruit in an attempt to become 'healthy'. This idea has now moved past homo sapiens and is infecting the diet of farm-raised fish and shrimp in an attempt to enhance growth while lowering production costs and reduce pollution.

Drs. Allen Davis and Connie Arnold of the University of Texas, Marine Science Institute have been looking at the nutritional requirements of fish and building diets that provide enough protein to achieve maximum growth. Tailor made diets and feeding regimes, can cut feed costs (farmers know exactly how much food the fish require) and can reduce pollution (by up to 1/4) as with leaner diets the fish excrete less waste. Part of their goal is also to try and determine the nutrition needs of fish at different points in their life cycles. "A lot of this research is geared towards not only developing the technology and demonstrating that these diets do produce good things, such as fast growth rates, but we're also giving the farmer another option for reducing pollution loads. The more information we have on nutrition, the more we can optimize how the nutrients are retained by the animal, this not only makes it cost-effective and reduces the pollution load," said Davis. Well-balanced, protein-rich feeds can reduce the amount pollutants released into fish ponds but are more expensive.

Typically farmers use cheaper, less nutrient-rich feeds to save money in the short-term, but in the long run they spend more money on feed because they will have to use more of it (this also creates more waste).

International the aquaculture industry is growing rapidly and this is a great thing as over-fishing and poor management has severely reduced the oceans ability to produce sustainable stocks. However the key to good aquaculture is good quality water and consequently makes environmental protection using sophisticated science an absolute necessity.

"In general, pollution from aquaculture is not a major problem, but we want to be proactive as far as maintaining a good environmental perspective. It doesn't do us any good to pollute our own water source", Davis said.