La. researcher uses light to grow bigger crawfish

A Louisiana researcher looking into ways to produce more and bigger crawfish in the same space says she’s had success with lighting the ponds at night. Julie Delabbio, director of Northwestern State University’s Aquaculture Research Center in Lena, says she has found putting underwater lights in crawfish ponds dramatically improves production. Her work is important as the U.S. looks to increase its domestic aquaculture. Ponds with a dozen underwater lights per quarter-acre produced about one-third to two-thirds more pounds of crawfish than unlit ones, Delabbio says. The work she’s done over the past three years found lit ponds produced 800 to 1,000 pounds of crawfish per acre compared to 500 to 600 pounds in unlit ponds. This year’s harvest was even better: Ponds without lights produced about 850 pounds of marketable crawfish per acre, compared to nearly 1,660 in those with lights, she says. The gains occurred in the size of crawfish as well as their number. Using lights to stretch the “day” has been used for decades to speed the growth of chickens, hogs and salmon; but the application with crawfish is new, and though Delabbio doesn’t know just why it works, she has three theories: The longer exposure to light may stimulate the animals’ 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.