Crawfish add more than $423 million annually to the Louisiana economy with more than $250 million at the farmgate.
"It's a significant business in Louisiana," says Mark Shirley, LSU area Extension agent, Abbeville, La. Shirley says the latest figures from the LSU AgCenter show producers managed 248,000 acres of crawfish in the 2018-19 season, producing more than 140 million pounds of crawfish.
Crawfish also mesh well as a rotation crop with rice and have helped support a depressed rice market for the past few years.
Those roles are reversed this spring as COVID-19 restrictions shuttered most restaurants, limited social gatherings that would have featured crawfish boils and sent the market tumbling.
Shirley says buyers cut quotas, so producers left significantly more crawfish in the ponds than normal. Those will carry over but could create issues with the next season's crop.
"Population density," Shirley says, "becomes a problem as ponds are more crowded, which will contribute to a stunting problem. Crawfish grow as long as they have enough room in the pond, but if they compete for food and space, they stay small. So many have been left in the field this spring, the remaining fish likely will stay small." Carryover crawfish will burrow in and be ready for harvest next year, Shirley adds, but at a small size.
"Crawfish farmers lost a lot of money this spring; they couldn’t fish, and the price dropped because buyers had a hard time selling."
That's an unfortunate result, preventing an opportunity for rice and crawfish rotations from enjoying robust markets at the same time.
Crawfish and rice work well together, says Dustin Harrell, professor and research coordinator at the LSU Rice Research Station in Rayne, La.
"Rice serves as forage for crawfish," Harrell says. "Producers can grow rice, harvest and leave the ratoon for crawfish. That's a common practice and offers a great symbiotic relationship."
Growers also may concentrate on crawfish and grow rice only as forage. "They plant rice late as a forage for crawfish, not putting much money into the rice crop."
He says the rotation has been a good system and for the past few years and helped keep rice producers in business. "Now, the crawfish segment is losing business and rice is potentially one of the more lucrative crops."
Shirley explains how the rotation works.
"Growers plant rice in March or April one year. Once the rice is 10 to 12 inches tall, producers put a permanent flood on. Usually in late May or early June they stock with mature crawfish. They harvest rice in July and August and reflood in October. In the winter and spring, producers harvest crawfish. Harvest typically runs through April and May."
They don't replant rice that year but plow and fix the levees. They plant rice again the following March.
"This rotation system runs on alternate years," Shirley says. "One spring they plant rice; the following winter and spring they fish crawfish."
Another production scheme uses more permanent ponds and concentrates on the crawfish year after year. "The primary crop is crawfish. Producers stock the field and follow best management practices for a permanent pond. They plant rice for crawfish forage."
Shirley says typical planting date for rice in permanent pond management is late July. "By the end of October, rice produces a green biomass. When they flood the field, crawfish come out with their babies and populate the pond."
Shirley says in the past few years, with crawfish making more money than rice, some producers skipped the rotation and converted to permanent ponds.
He says the two enterprises work together in either system as part of a big food chain.
"The crawfish and rice system is part of a big food web," Shirley says. "As rice vegetation slowly deteriorates, microorganisms, worms and insect larvae feed on decomposing rice plants and crawfish feed on all of that. The rice biomass creates part of the food web that crawfish depend on."
He says farmers may flush fields to stimulate regrowth of rice stubble and then keep it wet, maybe even shallow flood with about 2 inches of water through August and September. In October, they bring the flood level up to 10 to 12 inches to stimulate crawfish that had burrowed in. "In the cooler time of year, October and November, the crawfish emerge with babies."
Shirley says farmers need to be alert to potential low oxygen levels as straw begins to deteriorate after harvest and hot summer temperatures accelerate decomposition.
"That's why we have to pump and circulate water to aerate and keep the water healthy," he says.
Shirley says a viral disease, first detected in Louisiana crawfish in 2007, can cause massive die-off of large, mature crawfish.
"The crawfish white spot syndrome virus was first discovered in Southeast Asia shrimp farms in the late 1990s. It spread through Southeast Asia and then to South and Central America in 2006 and showed up here in crawfish ponds in 2007.
"Since then, we've seen it each year. We have no control options yet. We have no cure and, so far, we do not know how to manage ponds to prevent it.
"It's a strange virus that affects just the biggest crawfish. Producers may be catching well at the end of March and then in April the daily catch drops to almost nothing. Instead of 20 sacks every run, in a few days they catch just two sacks and they are small, immature, crawfish.
"The virus typically hits in the spring when water temperature begins to warm up — typically a few weeks before Easter," Shirley says. "This year, we saw it at the end of March and the first of April. We're still getting calls about it."
He says all the crawfish producing parishes in south Louisiana see the virus but not all experience significant losses.
"It is important to note that the virus does not affect people, other mammals, birds, fish or plants. The virus is specific to crustaceans. It started in shrimp and is sometimes found in crabs."
Shirley hopes research will find ways to cure, or at least manage, crawfish white spot syndrome virus. "LSU finally received some research dollars in February through a Louisiana Sea Grant program (similar to Land Grant funding).
"The funds were allocated, but just as we were getting ready to start, COVID-19 hit and closed down the labs. Everyone across the university system had to stay home."
Shirley says the Louisiana Crawfish Promotion and Research Board also allocated research dollars to LSU to study the virus.
"We were able to sample some ponds in the last month or so, but the full research effort is delayed. We hope to pick up again in the fall. By October or November we plan to gear up to do research and figure out how this virus survives year to year in a pond and how it moves from one pond to another. We also hope to determine if we can develop management procedures to lessen the effect."
He says ongoing research will be crucial to sustain a vital part of a symbiotic relationship with the rice industry and to maintain a significant contribution to the Louisiana agriculture economy.