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Increase Production Through Accurate Lighting

by the Fish Site Editor
16 July 2011, at 1:00am

Northwestern State Universitys Aquaculture Research Center is receiving nationwide attention for its research determining that underwater lighting increases production in crawfish ponds.

Studies conducted over three harvest seasons confirm that the use of underwater lights produces bigger crawfish and more crawfish in the same pond acreage with no additional water, according to Dr Julie Delabbio, director of the NSU Aquaculture Research Center in Marco.

“The research very much supports a sustainable farming practice with negligible environmental impact,” said Dr Delabbio, who has worked in commercial aquaculture for 30 years. The study, funded by the LSU AgCenter, also sought to determine whether the increase was significant enough to consider it viable for commercial farm application.

Earlier this week, the Associated Press released an article that was published on-line via several national news outlets from Washington, D.C., to Seattle, Washington, abuzz with the findings.

Production numbers are very detailed, Dr Delabbio explained. Every time traps were harvested over the past three seasons, crawfish were weighed and sorted into six size categories. Central Louisiana has only a three-month harvest season versus a seven-month harvest season in the southern part of the state. The Aquaculture Research Center surpassed the state average, which is 600 pounds of crawfish per acre, despite the shorter season and cooler water temperatures than the larger more southern crawfish farming centers in the state.

“Production results are really impressive,” Dr Delabbio said. “This year was a difficult year for many crawfish farmers because of the drought situation in the state. However, we had our best production year yet and we didn’t use any more water than we normally do.”

At the Aquaculture Research Center for the 2011 harvest season, the ponds with lights produced an average of 1,659 pounds of marketable crawfish per acre while the ponds without lights produced an average of 854 pounds of marketable crawfish per acre.

“The key word here is marketable. The total production from all of the ponds was higher but some crawfish are too small to market. If the lit ponds only produced more small crawfish than the technique would not be commercially viable,” Dr Delabbio said. “For us, marketable size is roughly a crawfish count of 35 crawfish or less to the pound when the crawfish weighs about half an ounce.”

The lighting impacts the size of the crawfish as well as the number of crawfish produced.

“If I just look at our ‘select’ grade crawfish production, the bigger crawfish, where the crawfish count is 20 crawfish or less to the pound the ponds with lights produced 1,148 pounds per acre while the lights without ponds produced 708 pounds per acre.” Delabbbio said.

The question of cost, however, is an important one. The focus of the research at the Center is looking at ways to increase crawfish pond production that have viable commercial application.

“In the past we have tried different things in the ponds to increase production and although they did make a positive impact, they were not cost effective,” Dr Delabbio said. “We decided to continue the underwater light research because the increase in production was significant and we believe with today’s technology a cost-effective way to use underwater lights is out there. LED lights are very inexpensive to operate and solar power, although initially expensive, allows the farmer to deploy lights in large ponds and in remote locations. It was first important to know that the lights do make a big difference to production, now the next step is to find the lights that are cost effective.”

Future research will determine how the light impact the basic biology of the crawfish. Factors to be investigated include the position of the lights in the water column, the length of time on a daily basis that the lights should be on, what month to start the lights and when to end the light treatment in order to get the greatest positive impact from the lights, Dr Delabbio said.

“Successful application of the technique is a bit trickier then just turning on the lights, but in our research so far, the technique shows great promise in being commercially viable,” she said. “One attractive aspect of the lighting research is that it is very eco-friendly. The addition of this technology has little negative environmental impact. At this point, we are trying to quantify the minimum amount of light required to get an increase in production with the industrial objective that lights on large crawfish ponds would be powered by solar energy.”

NSU’s Aquaculture Research Center is a 450-acre farm in operation for over 18 years with the objective of conducting research to support the state’s aquaculture industry. Most of the ARC’s research is focused on increasing production in crawfish ponds, Louisiana’s most significant aquaculture product, using sustainable practices.

“Our research always is business linked,” Dr Delabbio said. “The end result must have some usefulness to the bottom line.”

July 2011

the Fish Site Editor

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