Red claw are probably best produced in traditional fish production ponds 3 to 4 feet deep with sloping bottoms and a drainage system. Ponds ranging from 1 /4 to 2 acres have been used in red claw production, but ponds of 1 acre or less are recommended for ease of management and harvesting.
Research suggests the following production strategy:
- Stock juveniles of 1 gram or larger in the spring when water temperatures stay above 68o F;
- Stock at a density of 10,000 to 12,000 per surface acre of pond;
- Feed hay at 500 pounds per acre per month and supplement with a commercial diet at percent of estimated biomass:
- Partial harvest using traps starting 3 to 4 months after the young crayfish were stocked;
- Drain harvest when water temperatures drop below 60o F.
To reduce the chance of disease and competition, native crayfish should be eliminated from ponds in which red claw will be stocked. Fill the ponds with well water if possible to eliminate introduction of other species and their diseases.
Ponds should be filled only a few weeks before stocking to prevent the establishment of predaceous aquatic insects. Ponds should be limed if hardness is below 20 ppm and fertilized to establish a plankton bloom. Survival improves significantly if a 1 gram (28 to the ounce) or larger juvenile is stocked rather than newly hatched juveniles.
Stocking densities of 0.25 to 0.3 per square foot of pond surface area (10,000 to 12,000 per acre) appear to give the best overall survival and production of larger crayfish. Dried hay should be spread around the edges of the pond monthly at a rate of about 500 pounds per acre per month, divided into two or three applications.
Commercial crayfish, shrimp, or fish feeds should be used in addition to the hay during the last half of the culture period. Total commercial feed input should be fed at 3 percent of estimated total crayfish weight per day but not to exceed 35 pounds per pond surface acre per day.
Water quality must be maintained if red claw are to survive and grow. Aeration should be used to maintain dissolved oxygen above 3 ppm. Remember that these animals live on the pond bottom; therefore, oxygen should be checked near the pond bottom and not at the surface.
Ammonia and nitrite concentrations should be determined twice weekly toward the end of the growing season, but are not usually a problem at recommended feeding rates. If water quality declines, stop feeding and flush with clean water, if possible.
Red claw may attempt to migrate from the pond if water quality is poor. Proper management should lead to the production of 1,000 to 1,500 pounds per acre after six months. Individual red claw should weigh about 2.5 ounces or six to the pound, although some individuals will weigh more than 1 /4 pound.
Harvesting:
Red claw can be harvested by using baited crayfish traps, flowtraps, and by draining the pond. Crayfish traps used to catch native crayfish can be used for red claw. These traps are made of 3 /4- inch plastic coated chicken wire mesh (Figure 7).
Both stand-up and pyramid traps have been used effectively. Baits include formulated commercial crawfish baits and fish feed contained in small mesh bags. Final harvesting is done by partially draining the pond (to 1 /4 of original size) and setting up a flow-trap.
Flow-traps are traps through which water moves or flows. Red claw are strongly attracted to moving water, possibly an adaptive response to spring floods in their natural environment. Research suggests that flow-traps are very successful at capturing crayfish.
Pumping rates in flowtraps should not exceed 8 gallons per minute, and water from another pond or a well appears to work better than water from the same pond.
One flow-trap design is the box-nramp trap. The box-n-ramp trap consists of an impervious box (e.g., plastic trash can or metal drum) into which water is pumped and a ramp which carries the out-flow water to the pond bottom.
The crayfish move up the ramp against the flow and are trapped when they fall into the box. Adding fiberglass screen, vexar, or some other rough texture to the surface of the ramp will help the crayfish climb into the trap. Flow-traps must be checked often (every few hours) as they can fill with crayfish, causing those in the bottom of the trap to suffocate.
Diseases:
Red claw are probably susceptible to most diseases that affect native crayfish. In addition, red claw are susceptible to the “crawfish plague” which is a fungal pathogen. Native North American crayfish carry the plague but are usually not adversely affected by it.
The fungus was not known to be a problem until North American crayfish were introduced to Europe over 100 years ago. European crayfish had no resistance or immunity to the North American pathogen and many natural populations were devastated.
Research has shown that the red claw are susceptible to this fungus. The fungus grows best at temperatures below 65o F and does not appear to be active or pathogenic above 70o F. Since red claw need temperatures above 70o F for good growth, careful attention to stocking and harvesting temperatures may reduce potential problems. There are no known methods of prevention and treatment of the plague.
Authors:
Michael P. Masser and David B. Rouse
