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Freshwater Prawn in Ohio Aquaculture

by the Fish Site Editor
06 October 2009, at 1:00am

US On a recent cloudy morning at Ohio State Universitys South Centers at Piketon, a large group of visitors watched curiously as researchers and volunteers netted an aquaculture species many would consider out of place in Ohio: the freshwater prawn.

Basket after basket of the crustacean was hauled from a one-acre pond. When it was all said and done, over 9,000 prawns had been harvested (about 600 pounds). What started out eight years ago as a trial run for South Centers aquaculturists has turned into a yearly research project geared toward Ohio farmers looking for new crops and alternative income.

“What I find so fascinating about the freshwater prawn is that it is the size of a dime when you stock it in June, and by the time you harvest it 100 days later, it is the size of your hand,” said Laura Tiu, an OSU South Centers aquaculturist, who brought her knowledge of freshwater prawn production from Kentucky State University in Frankfort, Kentucky, to Ohio State University in the late 1990s.

“The prawn industry in Ohio is small, about 20 growers, but we add one or two new growers each year. Each year, we try to do applied research and hands-on technology transfer to help growers solve some of the problems they may be facing.”

Researchers conducted projects this year to address three issues: stock mortality, algae build-up in ponds and quality assurance, said Tiu, who has appointments with both Ohio State University Extension and the Ohio Agricultural Research and Development Center.

“One problem facing growers is that once you stock prawns in your pond, you don’t see them again until harvest, and one of the concerns is how many of those prawns survive the stocking process. This year we built three artificial habitats, stocked 20 prawns in each one and checked on the habitats daily,” said Tiu.

“We had 100 per cent survival rate in two habitats and we only lost one prawn in the third. So by having a simple tool like that, growers can be assured that their prawns aren’t suffering any stocking mortality.”

In a second project to reduce the amount of algae growing in nutrient-rich ponds, researchers planted winter wheat, rye and other nitrogen-reducing vegetation to reduce algae growth, while providing a habitat for the prawns.

“We had some algae reduction from previous years, but there was still plenty of it,” said Tiu.

“So it’s not a cure-all, but it may be an option.”

The third project involves the implementation of quality assurance procedures from a new manual developed by North Carolina State University and Mississippi State University.

“In order to give customers the high-quality product they demand, we are training farmers on improving the harvesting and post-harvesting process so that the prawns stay at optimal quality,” said Tiu.

During the recent freshwater prawn harvest, researchers demonstrated the new quality assurance procedures. One new step involves rinsing the prawns in a purge tank to ensure all dirt particles are removed from the tail meat.

“Prawns are bottom-feeders and the mud they ingest may not affect the quality of the meat, but from an aesthetic standpoint customers don’t like to see that,” said Tiu.

The other new quality assurance step involves chill-stunning live prawns to an optimum core temperature (38 degrees Fahrenheit or lower) to stop bacterial processes from degrading the tail meat.

The harvest and quality assurance demonstrations are a way for Ohio farmers to observe the prawn production process, see the product and determine whether or not prawn production is right for them. “Freshwater prawn is such a niche product that marketing it is tough. It’s expensive to buy – most farmers sell prawns for $8-$15 a pound. Because of the challenges, farmers have found success in incorporating prawns into an agritourism business,” said Tiu.

“Where we come in is we invite people to take part in our research. We provide technology transfer around the state, and offer fact sheets and other information. When people call us and say they are interested in prawn production, we send them information, and then we invite them to our facility, analyse what resources they have and need, and put together a business plan so they can make a decision as to whether or not this is a good alternative crop for them.”

the Fish Site Editor