Hurricane rains problem for Louisiana crawfish
Sep 9, 2008 12:46 PM
Rain from Hurricane Gustav across the crawfish-producing areas of Louisiana may cause problems for crawfish producers, according to LSU AgCenter aquaculture specialists Greg Lutz and Mark Shirley.
“Rainfall ranged from a couple of inches to more than 20 inches in a few isolated spots,” Lutz said. “Even though this is free water, it may cause producers to lose crawfish because water quality quickly deteriorates.”
“This time of year, it is better to drain the stormwater out of crawfish ponds as soon as possible,” Shirley said. “In the coming weeks, daytime temperatures will be in the 90s again, and trying to maintain water quality through pumping and flushing will be economically impossible.”
If the field has rice or rice stubble, producers can keep a couple of inches to help the rice continue growing during September.
“If sorghum sudangrass was planted as crawfish forage, drain the field completely as soon as possible,” Shirley said. “Ponds with wild vegetation of grasses and sedges should be completely drained as well.”
Lutz said poor water quality is often a serious problem in crawfish ponds as well as fish ponds and waterways after tropical storms and hurricanes have passed.
“A fundamental problem with flooding crawfish ponds early is that the warmer water has less dissolved oxygen, regardless of how much the water is pumped and aerated,” Lutz said.
Vegetation blown down into the water rapidly decomposes, using up all the dissolved oxygen in the water. When this happens in a crawfish pond, crawfish will crawl out of the pond to escape the bad water. They are then easy prey for predators or dry up in the hot sun. Fish kills can also be expected as the same decomposition process occurs in ponds and bayous in the days following a storm.
“Typically, only a small percentage of female crawfish spawn in early September.” Lutz said. “The majority of the females will lay their eggs later in September and on into October. So even if some crawfish are crawling around right now, the majority of the carryover or stock crawfish are still in the ground.”
Unless the levees are covered with water for several days, most of the crawfish will stay in their burrows and be safe until it’s time to flood up in October, the specialists said.
For more information on the effects of Gustav on crawfish and other crops, contact your LSU AgCenter parish Extension office.
