August 2011 Articles

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LSU AgCenter experts help crawfish farmers increase their yields

LSU AgCenter experts help crawfish farmers increase their yields OPELOUSAS, La. – LSU AgCenter crawfish researchers gave recommendations to producers on improving their crop and avoiding or reducing problems in their ponds. Robert Romaire, LSU AgCenter aquaculture specialist, advised that algal scum that grows during cold weather will die in the spring, and the decaying vegetation will deplete oxygen from the water. He said the condition could be evident in the next 3-4 weeks with the recent warm weather. Romaire said low oxygen levels will stress crawfish, decreasing growth, increasing mortality and decrease crawfish shelf life after they are harvested. He recommended producers buy test kits to determine oxygen levels in ponds. “When crawfish get into a growth or molt stage, they are real susceptible to oxygen stress,” Romaire said. Research has shown that feeding crawfish a supplement is probably a waste of time and money, Romaire said. He also said releasing small crawfish when they are caught is not a good idea. Population density is a key factor for getting larger crawfish, he said. Mark Shirley, LSU area aquaculture agent, advised producers to stock their ponds before June to avoid exposing the transplanted crawfish to intense summer heat. He said the recommended stocking rate is 60 to 70 pounds per acre. Ray McClain, LSU AgCenter crawfish researcher, said fields should remain flooded for a few weeks after stocking. “You need to give them an opportunity to burrow before you drain a field.” Crawfish farmers report their catches have started to improve with warmer weather. McClain said this year’s crop appears to be lagging from previous years because crawfish were late in emerging from burrows. “We’re way behind where we were this time last year.” Romaire said crawfish caught in ponds with good water quality and properly handled after harvest can be stored for as long as five days in coolers after harvest, if they are kept cold and the sacks are not stacked too high. He said sacks of recently molted crawfish are damaged more easily. McClain said weather and the health of the animals play a large role in whether a successful season will unfold. Peak spawning takes place as early as late July through September and October. Females will burrow into the ground nearly three feet deep where they will lay their eggs and hatch their young. An unusually dry period during this time can lead to a high mortality rate in the burrow of both mature and juvenile crawfish contributing to a poor season. Rainfall is also important during the early fall months, he said. “A mature crawfish needs rainfall to soften the plug on the burrow. Without sufficient moisture during this time the female and young cannot escape the burrow,” McClain said. McClain said just because the harvest is slow this time of year, it may not equate to a poor season. “The season may just be delayed. The crawfish are there in many cases. They just haven’t reached a marketable size.”