Researchers at The Ohio State University South Centers, partially funded by Ohio Sea Grant, are breeding yellow perch that thrive in aquaculture operations, growing about 30 percent faster than unimproved fish and reaching market size in 12 or 13 months instead of 18 months. These fish could increase profit margins on fish farming, making it more economically feasible for farmers.
Han-Ping Wang and his colleagues are currently conducting on-farm and on-station trials in Ohio and Wisconsin, with four separate locations providing a wide range of climates in which to raise the experimental fish. To breed the current third generation of genetically improved perch, the researchers are using DNA markers to separate sibling fish, thereby avoiding inbreeding that can slow growth rates and make fish more susceptible to disease. When combined with more traditional selection of favorable traits like size and overall health, this approach leads to a marked improvement in growth and resilience for the fish.
"Our improved fish grow faster, so at the end of that culture period, the percentage of marketable size fish will be much higher."—Han-Ping Wang
"One of the reasons is that they genetically utilize the feed better," said Wang, director and principal scientist for the Ohio Aquaculture Research and Development Integration Program (OARDIP) at the South Centers. "So that means they use the same amount of feed, but they can reach market size in a shorter time. And that saves a lot of time, a lot of labor, a lot of feed, and a lot of cost."
Because of the way some of the experimental fish were raised, the researchers also found that the genetically improved fish seem to be more resilient to overcrowding in farm ponds. Despite tight living space and less feed for individual fish due to higher than expected survival rates, the improved fish still grew about 30 percent faster than unimproved fish, with less variation in size.
Faster growth and more uniform size at the end of the culture period would be a definite advantage for fish farmers, who traditionally raise perch for 18 months to have only about 50-60 percent of the slow-growing fish be of a size suitable for sale. "Our improved fish grow faster, so at the end of that culture period, the percentage of marketable size fish will be much higher," Wang said.
Good for fish farmers, good for Lake Erie
More than 2.8 million pounds of yellow perch were harvested from Lake Erie in 2011. While the fishery is carefully managed, demand for the fish can put a strain on the ecosystem, and perch aquaculture could reduce that strain while providing new business opportunities. Once the commercial market for these fast-growing fish is established, the number of farms growing yellow perch for food could rise quickly, as fish is valued as a lean, healthy protein source for a human population that continues to increase.
More information about this project will be available in the upcoming issue of Ohio Sea Grant's Twine Line newsletter, http://ohioseagrant.osu.edu/publications.
-- Christina Dierkes, Ohio Sea Grant Communications