A Lit Pond Produces More, Bigger Crawfish: Research

In an attempt to find ways to produce more and bigger crawfish, a Louisiana researcher said, she's had success with lighting the ponds at night and also believes that her work could pave the way for expanding crawfish farming in cooler areas, an AP report said.

Crawfish which is one of the nation's biggest aquaculture crops is harvested second only to catfish in most years. While Louisiana is the largest producer of the fresh crawfish, they are also raised in Europe and Australia.

The scientist Julie Delabbio, who is the director of Northwestern State University's Aquaculture Research Center in Lena, said that underwater lighting of the crawfish ponds dramatically improves its production. With the US looking forward to increasing its aquaculture, this discovery is very important.

Per quarter-acre of the pond with a dozen lights produced about one-third to two-thirds extra pounds of crawfish than unlit ones, Delabbio said.

The improvement was seen not only in the number of crawfish, but also in size.

Just getting more crawfish isn't necessarily a good thing if you're getting a lot of little crawfish, Delabbio said. We're getting more sellable crawfish out of the ponds with underwater lights,” she added, according to the report.
The practice of stretching the day using lights has been used for decades in order to speed the growth of chickens, hogs and salmon, but the application with crawfish is new and Delabbio herself doesn't know just why it works.
She has three theories which might be an explanation to the phenomena: the longer exposure to light may stimulate the animal's metabolism, as it does with chickens and hogs; the light may stimulate the growth of plankton, plants and insects, providing the crawfish with more food; or the lights may attract smaller invertebrates, creating spots where crawfish can get an easy meal without expending a lot of energy.
But Stephen Minvielle, the director of the Louisiana Crawfish Farmers Association pointed out about the expense of lighting the pond.
The economics of running lights of any size in a crawfish pond would run you bankrupt in about a month, he said. A one-kilowatt metal `halight' probably burns $65 a month, running it eight hours a night, he added.
Delabbio says, she expected that lit ponds would mostly interest farmers from central and north Louisiana, where the season is much shorter - four months, at most, instead of about seven.
Getting more production with such a short season and such a different climate could be a big help, she said. And, she's working to find ways to reduce the cost.
She said that the thing that excites her the most is the fact that lights could provide more crawfish without any need to increase the amount of pond space and water.
I can't think of any negative environmental impact, she said.