Crawfish: Give me air!

Crawfish Report, the news for crawfish nation....

Crawfish Report, the news for crawfish nation….

LAKE CHARLES, La. – With crawfish season starting, experts with the LSU AgCenter and Louisiana Sea Grant offered advice Tuesday (Dec. 15) for producers to improve their harvests.

Two dozen producers attended the event at the Calcasieu Parish AgCenter extension office.

Kevin Savoie, AgCenter and Sea Grant agent in Cameron Parish, said recent warm weather has been good for the start of crawfish season.

“Things really look good right now,” he said.

Greg Lutz, an aquaculture specialist with the LSU AgCenter and Louisiana Sea Grant, said checking the oxygen level in pond water is essential for creating an environment for a good crop. He asked for a show of hands of those who monitor the amount of oxygen in their crawfish ponds, but no one responded.

“I’m just going to say this: You can’t control something you don’t measure,” he said. “That’s probably the single thing you can do to make money.”

Lutz compared failing to monitor and maintain oxygen levels to not fertilizing a rice field. “If you’re not managing your oxygen, you might as well go on vacation,” he said.

Adding oxygenated water to a pond with good oxygen levels is a waste of money, he said, and failing to pump oxygenated water into a pond with low oxygen will result in fewer crawfish.

An inexpensive testing kit can be used every two to three days in the fall, he said.

Planting vegetation for crawfish too early in June results in depleted oxygen early in the crawfish season as the vegetation will already be mature by early autumn, Lutz said.

Warmer water holds less oxygen. For example, Lutz said, water that is 80 degrees loses oxygen twice as fast as 70-degree water.

A mechanical aerator such as those used in catfish ponds probably isn’t worth the expense, he said. The simpler, cheaper method of adding oxygen is pumping water over a simple tower structure to break the water flow into droplets, with the potential to add 3-3.5 parts per million of oxygen.

Stocking should be done with females that have advanced eggs. The size of stocker crawfish does not matter, he said, because environment, not genetics, determines size.

Flooding too early also will result in rapid breakdown of vegetation, much of which won’t last into the late season, he said.

AgCenter crawfish researcher Ray McClain said harvesting is the most costly operating expense of a crawfish operation.

A study at the LSU AgCenter H. Rouse Caffey Rice Research Station in Crowley showed that only half of the crawfish released for further growth after being caught were ever captured again.

He said it’s best to remove crawfish that are captured, regardless of size.

Low crawfish populations need fewer traps, he said, probably 10-14 per acre, while high crawfish populations can justify 16-20 traps an acre.

Traps can be run every 48 hours in cool weather, but that can be increased to every 24 hours in warm weather when the catch is good. In exceptionally warm weather with a high catch rate, traps can be checked every 12 hours but only for a few days, McClain said.

McClain also advised against throwing bait that’s several days old into the pond because the food could attract crawfish away from traps.

He said deep water isn’t needed for crawfish, but water levels should be deep enough to discourage wading birds from feeding on crawfish. High water will lead to earlier vegetation loss, he said, but some depth is needed to act as a buffer from cold temperatures.

More producers who also grow rice are switching to push boats because they don’t rut the fields like hydraulic boats, but the non-mechanized push boats are still used by farmers who have the equipment to refurbish the pond bottom.

Persistent low oxygen early in the season could result in death of young crawfish, McClain said. “If you lose that early recruitment class, you’re not going to catch many early in the season, and you may not catch much until March or April.”

Lutz urged producers to call AgCenter agents for help if crawfish start dying. “If you see crawfish dying, get on the phone and get some help,” he said. “You’ve got nothing to lose and everything to gain.”

Bruce Schultz