Ph.D. student Amy Alford sets a trap in a wetland.
By Richard M. Kaminski, Ph.D.
Mississippi Delta farmer, Léonard Gibeault said, “Look at all the crawfish around the drain pipe in the duck hole. Get the dip nets from the truck, Aaeeeeeeeeh!” Indeed, crawfish (aka “crayfish”, “crawdads,” “mud-bugs”) are native invertebrate crustaceans, abundant in wetlands in the Mississippi Delta, Louisiana, and throughout the Southeast.
One prime habitat where crawdads occur naturally is moist-soil wetlands. These totally naturally grass-sedge dominated wetlands, often managed for waterfowl and duck hunting, team with crawdads during spring and into summer until the wetlands dry and the crawdads burrow deep into the soil to survive the dry season.
Most of the crawfish we all enjoy at springtime-boils come from rice fields and the Atchafalaya Basin in Louisiana. Although Louisiana leads the nation in crawfish production, moist-soil wetlands and swamps throughout Mississippi and other states in the Lower Mississippi Valley provide suitable habitat for native crawfish, ducks, and other wetland wildlife.
Léonard Gibeault and scientists in the Department of Wildlife, Fisheries, and Aquaculture at Mississippi State University have known for years about the existence of crawfish in Mississippi wetlands, but no scientific investigations of crawfish ecology in moist-soil wetlands have been conducted. Additionally, scientists have been studying various aspects culturing crawfish in rice fields, but no attempt has been made to quantify yield of crawfish from natural habitats.
Unlike commercial crawfish culturing in Louisiana, where ‘stocker’ crawfish are captured in swamps and then transported to rice fields where they reproduce, grow, and then are caught in baited traps and marketed, crawfish harvests in moist-soil “duck holes” rely only on native, naturally occurring crawfish. These “mud-bugs” burrow deep into the soil after duck holes are drained during spring-summer, leaving above the ground a mud “chimney” marking the site of their earthen summer hibernaculum. When duck holes are flooded in winter, juvenile and adult crawfish emerge from their earthen burrows, scavenging plant and animal foods from the bottom of wetlands.
MSU scientists decided to capitalize upon values of moist-soil wetlands for wintering waterfowl and water-quality improvement by initiating research to evaluate crawfish production from these wetlands and their economic values. A team of investigators including Ph.D. student Amy Alford and graduate advisors, Drs. Rick Kaminski, Jimmy Avery, Lou D’Abramo, Steve Grado, and Robbie Kröger, designed a survey to harvest crawfish from managed moist-soil duck holes in the Delta region of Mississippi, Arkansas, Louisiana, and Missouri.
The MSU study mimics commercial crawfish harvest strategies as employed in Louisiana. Approximately 12 traps are deployed per wetland acre, baited with crawfish bait made from fish meal, corn and soybeans. The traps and bait are the same commercially-available products used by crawfish farmers in Louisiana rice fields. Harvesting the crawfish takes place from April through June, with the traps set in about 18 inches of water. Crawfish are most active in the wetland when water temperatures reach about 65 F, which increases catch rates. After harvest in summer, duck holes are drained to promote growth of seed producing moist-soil grasses. The seeds provide important food for wintering ducks, and the decomposing grasses provide a substrate rich in foods for crawfish.
Crawfish harvest from duck holes will not compete with commercial production from rice fields in Louisiana. Costs associated with planting a forage crop, such as rice, machinery, transportation, and labor for commercial crawfish production can range from $450 to $700 per acre. To profit, farmers harvesting crawfish from Louisiana rice fields must harvest at least 10 pounds per acre per day. On average, daily production of “duck-hole dads” is about 2 pounds per acre.
However, the costs associated with crawfish harvests are reduced when a landowner wants to harvest the crawdads that exist naturally in Delta wetlands and are not stocked as in Louisiana. The vegetation forage base naturally grows in the wetland and less machinery is used to manage a wetland compared to a rice field. The big expense in harvesting crawfish from moist-soil wetlands comes mostly from the time it takes to tend to traps. The traps cost about $8 each or can be easily made by hand for around $5 each. The formulated bait is readily available at local feed and seed shops and typically costs $12 for a 50-pound bag. However, waste chicken, fish, and other meats can be used.
One big question asked by the research team and public is, “How do “duck-hole dads” taste compared to Louisiana crawfish?” The misconception that duck-hole wetlands are “mire-like,” “swampy,” or “dirty” has led some folks to think that naturally produced crawfish will taste dirty or muddy. Even in south Louisiana there has always been the debate over the taste of rice-field crawfish and swamp or naturally produced crawfish.
To tackle this debate, the researchers collaborated with Dr. Wes Schilling in the Department of Food Science, Nutrition, and Health Promotion at Mississippi State University to conduct a taste test analysis and let the crawfish consumers be the judge. “We had volunteers from the community and university come to our lab and rate the taste of ‘duck-hole dads’ and commercially harvested crawfish from Louisiana,” explained Dr. Schilling. “Interestingly, about 150 panelists rated ‘duck-hole dads’ and the rice-field crawfish as well liked.” Guess that debate was put to rest!
Motivation for this research wasn’t only to catch and eat crawfish. Landowners and managers in the Delta and beyond are actively participating in wetlands conservation by management of duck holes. Over 50,000 acres of wetlands are enrolled in federally funded programs, such as the Wetlands Reserve Program in the Mississippi Flyway alone. And, these wetlands aren’t only providing places for ducks and hunters. Wetlands are considered “kidneys of the landscape” because they act as filters for nutrients washed off of farmlands and human-populated areas. Without wetlands, much more nutrient-rich water would enter streams and rivers and eventually travel to the Gulf of Mexico and increase the Dead Zone. The research team is also investigating the potential of duck-holes to increase water quality in downstream water bodies in Mississippi.
The researchers believe that creating duck-holes provide additional sources of human food (crawfish) and recreation (hunting, wildlife watching, craw-fishing), as well as provide incentives for landowners to practice wetlands conservation. Additionally, managing moist-soil wetlands will help improve water quality and replenish underground aquifers. The researchers also are considering marketing the idea of crawfish production in the thousands of acres of now idle catfish ponds in the Mississippi Delta that are growing up in natural moist-soil vegetation.
While currently the Mississippi Department of Wildlife, Fisheries, and Parks and the Louisiana Department of Wildlife and Fisheries do not have regulations regarding the harvest of crawfish from managed wetlands, other states including Arkansas and Missouri have harvest restrictions to protect these and other aquatic organisms against overharvest. The Southeast United States has the most diverse community of crayfish in the world. Many species are at risk of extinction if removed. Therefore, if you are interested in catching crawfish to eat, make sure you are catching the right species and have the appropriate license or permit. Typically, two species of crawfish are abundant in duck holes, the White River crawfish and the Red Swamp crawfish and you likely won’t catch enough to overharvest them.
So grab a few traps and some bait, find a good duck hole, get your friends and family together, and contribute to the conservation of wetland habitat by catching and consuming your own crawfish.
Crayfish Photo credit: Holger Leyrer | Dreamstime.com