|The Bigger, Better, Super-Sized Perch - Faster-growing fish could make yellow perch aquaculture more viable|
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This story was printed with permission from Ohio Sea Grant.
It's Friday night, and you're heading to the local pub to grab some fried fish and watch the big game with some friends. If you're in northern Ohio, chances are good that your sandwich will feature yellow perch, a popular fish from Lake Erie that is also Ohio's top food fish, with 3 million pounds harvested from the lake in 2008 alone.
With demand for yellow perch so high, it makes sense that fish farmers have begun to cultivate the species as part of an Ohio aquaculture industry that has tripled in size in the last decade - from $1.6 million in 1998 to $6.6 million in 2007. However, yellow perch are a slow-growing species, often taking two years to reach a "market size" of 8.5 inches. This extended growing period can cost a bundle, particularly as the price of fish meal has skyrocketed in recent years, making it a serious drawback for farmers who might consider taking the perch-raising plunge.
But there is hope on the horizon. Ohio Sea Grant Researcher Hanping Wang, director of the Ohio Aquaculture Research and Development Integration Program at the Ohio State University (OSU) South Centers in Piketon, has been working to selectively breed yellow perch that are expected to reach market size in just one year. To date, it's an experiment that has yielded impressive results.
"Our genetically-enhanced stocks grow 28% to 42% faster than the typical fish and have potential to reach market size in just one year," Wang says. "Reducing the amount of time before the fish can be harvested should decrease costs for care and feeding by 30% to 40%. This is good news for fish farmers."
Finding Genetic Fingerprints
Part of the trouble with current yellow perch aquaculture populations is that there has been little concern about inbreeding, which can not only contribute to the slow growth rate of the fish but also make them more susceptible to disease. Wang knew that breeding for bigger fish would require careful control. "We did not want to breed siblings or cousins," he explains.
After breeding the fish and raising them to market size, they selected the top 5% to 10% of the biggest fish and tested their genetic relatedness using a technique that looks for genetic fingerprints in a fish's DNA.
The fingerprints help them to determine the parents of each fish so that only those fish that are not related and have the best physical characteristics will be bred further.
Wang has been able to do this step quickly thanks to a new machine called the Genetic Analyzer, which can genetically fingerprint 800 fish in two weeks - a process that used to take three months.
After five years of work on this project, Wang has established five lines of improved yellow perch. To this point, however, he has only bred his superior fish in the research breeding center. To be sure the improvements translate to a commercial scale, they must first be tested at some fish farms.
"Our study so far has been at an experimental scale," says Wang. "We need to test it at an industrial scale, so we have recruited four farms - two in Ohio and two in Wisconsin - to test the new fish from 2011 to 2013."
One of those farmers will be Bill Lynch, an OSU Extension Associate who also raises yellow perch in Union County, Ohio. He sees the farm test as an important part of Wang's development of improved yellow perch.
"You can demonstrate the genetic improvement in small-scale lab situations, which he's done, but you still better make sure it holds up at the commercial scale," Lynch says. "If you don't, there's no sense from the farmer's standpoint in spending extra money on genetically improved stock. The grower has to see the improvement."
Farmed fish are often purchased as fingerlings and grown in ponds or tanks until they reach market size. A well-managed commercial pond in Ohio, ranging from a quarter- to a half-acre in size, can produce between 3,000 and 3,500 pounds of yellow perch per acre, yielding a potential 2,500 to 5,000 perch per pond.