News Release Distributed 09/01/12
Hurricane Isaac has dropped a significant amount of rain this past week in some parishes. Although it may be tempting to hold this water as a means of flooding crawfish ponds early and for free, this is the wrong thing to do, according to LSU AgCenter aquaculture specialist Greg Lutz.
“With four to six more weeks of hot weather, holding water in the ponds will very likely lead to crop failure,” Lutz said. “It is still better to drain off this storm water and wait to flood the ponds in late September or, better yet, early October.”
Heavy rains associated with Isaac will cause some, but not all, brood females to emerge from burrows, Lutz said. Holding storm water in early September to save these early emerging crawfish is not a good idea.
“The temperature of the water will get too hot, and the rotting vegetation will deplete the dissolved oxygen in the water resulting in extremely high mortality,” Lutz said.
Unless the pond levees are flooded over for several days, only a portion of the brood stock will actually emerge from the burrows. Most crawfish will remain in the burrows, where they are protected from these lethal conditions.
“The bottom line is that it is better to lose a few early emerging crawfish than to risk losing most of the holdover crawfish and all of their babies,” Lutz said.
Mark Shirley, LSU AgCenter aquaculture specialist in the Acadiana region, adds that in ponds where summer-planted rice is tall enough to tolerate a shallow flood, holding a few inches of water may be all right. The rice will continue to grow, and if there are few weeds, the water quality may not get too bad. In ponds where rice was harvested and there is plenty of straw on the ground, rainwater should be drained from the field.
“While the water will help stimulate the rice stubble to re-grow, water quality will be lethal in just a few days,” Shirley said.
Some farmers plant sorghum-sudangrass for crawfish forage. Shirley said this plant grows well during dry August and September months, but excessive rainfall will often kill this plant, unless the water is drained off fairly quickly.
Another problem that sometimes comes with storms is the flood water introducing predaceous fish into the crawfish ponds. Lutz said that small green sunfish (bream) and bullhead catfish can eat a tremendous amount of small crawfish early in the season. Draining the flood water will strand and kill these predators.
“Understandably, high water in drainage ditches, canals and bayous may prevent you from getting rid of excess water quickly, until river stages recede,” Lutz said, adding that the quicker the flood water can drain form the pond, the better.
If you have any questions about your particular situation, contact one of the LSU AgCenter crawfish specialists: Greg Lutz at 225-765-2848 or glutz@agcenter.lsu.edu; Mark Shirley at 337-898-4335 or mshirley@agcenter.lsu.edu; or Robert Romaire at 225-765-2848 or rromaire@agcenter.lsu.edu.
Bruce Schultz