Harvesting is the most expensive part of producing crawfish, so reducing that cost can mean the difference between profit and loss, according to Robert Romaire, LSU AgCenter aquaculture specialist, who spoke at the 2007 Crawfish Farmers Association 2007 Expo at Rayne, La.
Romaire said 3/4-inch square-mesh pyramid traps are the most effective. Bait fish work best in colder water — less than 70 degrees — while manufactured bait works better at warmer temperatures and is less expensive.
Traps should be baited with no more than one-third pound of material, he said. The most effective number of traps is 10 to 15 per acre in a low-density pond common to Louisiana, but 18 traps to 22 traps per acre are recommended for high-density ponds.
Harvesting every other day provides larger crawfish, he said.
Fluctuations are common in harvests, Romaire said, with the catch declining around the time of a full moon, which stimulates the molting phase for crawfish.
“That’s true of other crustaceans, such as crabs,” Romaire said. “They won’t feed until their shells harden.”
Flushing a pond sometimes prompts molting, he said.
Catches generally decline after a cold front, Romaire said, and improve after rainfall.
Romaire said the white spot syndrome virus that struck numerous ponds earlier in 2007 may not be as much of a problem after all. He said research, partially funded by crawfish producers’ self-assessed fees, is being done to learn more about the disease.
But he said LSU AgCenter research ponds near Baton Rouge that tested positive for the disease earlier this year produced crawfish as well as ponds where it was not found.
He said two-thirds of Louisiana ponds sampled this year were positive for the virus, and a third of crawfish from the Atchafalaya Basin tested positive also. Ponds will not be quarantined, he said.
Ray McClain, LSU AgCenter crawfish researcher, said crawfish are now producing young in a commercial pond where the virus had been found to have affected production.
“The pond appeared to have recovered somewhat,” McClain said. “The adult crawfish appeared to be healthy, and the offspring appeared to be healthy.”
He said apparently the virus may not be a problem until crawfish become stressed or environmental conditions trigger an outbreak, but researchers currently know little about this disease in crawfish.
McClain stressed that humans cannot get the virus.