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Raising Twice the Yellow Perch Soon Possible

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Written Monday, July 03, 2000  

Aquaculture farms soon will be able to cheaply and successfully raise two crops of high-value yellow perch per year, says Konrad Dabrowski, Ohio State aquaculture specialist.

A process of controlled reproduction and growth of yellow perch could be available commercially by next spring, Dabrowski says. The process would enable fish farmers to get two spawning cycles per year, rather than one, and use the resulting young fish as feed for up to a 98 percent lower cost than the best commercial feed, without a loss in growth performance.

Yellow perch is in such high demand that consumers pay up to $15 a pound for it. It has little fat and its products have a long shelf life, resist freezer damage and rarely have an off-flavor.

Each year, the Great Lakes yield 11 million to 18 million pounds of yellow perch while aquaculture farms contribute another 200,000 pounds. But the market could absorb up to 100 million pounds of yellow perch each year, according to data from the USDA's North Central Regional Aquaculture Center, which helped fund OSU's recent study.

With fisheries in the United States and Canada declining and demand already higher than supply, there is a great need for increased aquaculture production of yellow perch.

In 1996, Ohio State researchers used water temperature and light manipulations to cause the perch to spawn again in August and September, months after they naturally spawn in April and May.

While two crops could be produced, they couldn't be successfully or economically raised in captivity using artificial diets or live food, such as brine shrimp, until this spring, Dabrowski says.

The problem was the artificial environment.

If the tank's temperature, light, water clarity and other conditions were not as close as possible to the perch's natural habitat, their natural instinct to swim to the surface and take in an air bubble to fill their swim bladders may not be triggered, Dabrowski says. This would leave the young perch without their natural buoyancy--an ultimately fatal condition.

Another problem is high feed cost. Fish farmers have had to provide live brine shrimp, which run about $110 per pound to buy and rear. The best commercial artificial feed is about $40 a pound.

In contrast, dry diets fed to other fish cost less than 75 cents per pound. But yellow perch don't like dry feed, Dabrowski says.

Ohio State studies have shown that coating dry feed with liquid protein makes it more appealing to the yellow perch, which eat two to three times more of it than of the dry feed, Dabrowski says.

On the coated feed, the fish grow larger and fewer of them die. They also can be weaned off live food and onto an artificial, and much less costly, diet one or two months earlier than usual, he says.

Apart from the cost savings, this development was important because it opened research opportunities to further identify substances in the low-cost coated feed that have attractant properties, he says. The dry diet sprayed with the krill hydrolysate costing costs only about 80 cents a pound.

"In spring 2000, yellow perch larvae were raised on Ohio State University's Columbus campus, and in some batches more than 70 percent successfully filled their swim bladders and showed excellent growth," Dabrowski says. "Several thousand of the juvenile fish were then transferred to an artificial diet and continued to grow. This basically means that two technologies, controlled reproduction and larval rearing, can now be tested on a larger scale for commercial success."

The next step will be to enrich the diet to reduce disease and further improve yellow perch production, he says.

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