The method by which crawfish are harvested is unique compared to methods use to harvest other cultured aquatic animals. Unlike catfish, bait minnows, trout, and shrimp that are harvested one to several times annually with nets or seines, crawfish are harvested 30 to 60 days per year (April through June) with small wire or plastic traps baited with fish or manufactured attractants.
As many as 30 different crawfish trap designs have been used to harvest crawfish by the crawfish industry nationwide. Traps differ in design and configuration, physical dimension, construction material and mesh size, number of entrance funnels (flues), presence or absence of support rods, retainer bands or collars, and presence or absence of bait wells.
Traps are constructed from 3/4-inch hexagonal mesh wire (19-20 gauge PVC-coated wire being the most common) or extruded plastic. The mesh size is selective for crawfish 2 3/4 inch long and larger. Crawfish traps are generally categorized as being of a "stand-up" or "pillow" type. Stand-up traps are set in an upright position in the water with the top of the trap protruding above the water surface. Pillow traps lay horizontally on the pond bottom and are generally completely submerged. Stand-up traps are made in several designs and they are the most common traps use by crawfish producers, especially in North Carolina. Pillow traps (named because of their pillow-like shape) are generally reserved for fishing in waters too deep (greater than 36 inches) for most stand-up traps. A pillow trap that is set upright is called a stand-up pillow trap.
There are four basic stand-up trap designs are used by crawfish producers: 1) pyramid, 2) stand-up pillow, 3) barrel, 4) rooster-tail. The pyramid trap is the most commonly used trap in North Carolina followed by the stand- up pillow trap and the barrel trap. The rooster-tail trap is not used at all in North Carolina. The pyramid trap is triangular in shape, stand-up pillow traps are oval, and barrel traps are cylindrical. The rooster-tail trap, often called the "high-rise" trap, is a "hybrid" of the stand-up and pyramid design. The four basic trap designs are all effective in trapping crawfish and selection of design by a producer is often a matter of personal preference. A producer often finds that a particular trap design is better suited for his pond(s) and method of harvesting. Traps retail for $8 to $14 each, but $10 is a common price. Many trap vendors sell crawfish wire and other supplies such as pliers, hog rings, support rods, and collars for producers to be able to make their own traps (at a considerable savings).
Researchers have investigated the catch ability of 30 different trap designs. The results showed that there was no difference in the catch ability between the stand-up pillow trap, the barrel trap, or the rooster-tail trap. The pyramid trap did catch 20-34% more crawfish than the stand-up pillow trap. Larger traps (traps 30 inches high and 15 inches in diameter) appear to catch more crawfish in ponds with large harvestable crawfish populations than smaller traps (traps 30 inches high and 11 inches in diameter) because smaller traps become saturated with crawfish quickly and thus prevent additional crawfish from entering the trap. Traps made from PVC-coated wire or plastic wire caught 15-25% more crawfish than galvanized wire. Traps with 2 or 3 funnels caught 2 to 3 times as many crawfish as single funnel traps. Traps with 3 funnels caught 20% more crawfish that 2-funnel traps during short trap sets (12 hour sets or less). During 24-hour trap sets, there was no difference between the 2 and 3-funnel traps. White plastic wire traps caught 37% fewer crawfish that black plastic traps and 45% fewer crawfish from black PVC-coated traps. Retainer rings made from 3 inch wide strips of thin aluminum on the inside circumference at the top of the open area of the trap or collars made from 4 to 6 inch diameter PVC pipe attached at the top of the trap can increase catch 15-20% over traps with such devices during a 24 hour trap set. The retainer devices did not have much effect during 12-hour trap sets. 15% to 20% of the crawfish that enter a trap's are able to escape through the entrance funnels within 24 hours while 40% to 60% can escape in 48 hours. Traps with bait wells baited with shad caught 40% less crawfish than traps baited with shad without bait wells. When manufactured bait was used, traps with the wells caught 15% fewer crawfish. Trap sets of 12 hours will catch more crawfish than 24-hour trap sets, especially when water temperatures are above 65oF and if manufactured baits are used. A 12-hour night set is generally more effective than a 12-hour day set when water temperatures are cooler, otherwise there is no difference. The best density for traps in a pond is 15-20 per acre. Fishing only 3-4 days per week optimizes crawfish catches. In other words, you catch as many pounds of crawfish per year by fishing the pond 3-4 days per week as you would fishing 6- 7 days per week during the year. The optimum time to begin fishing a pond is after the water temperatures have reached 65oF, which is typically around the first of April in North Carolina.
Fig.13-Crawfish Producers Running Traps
Therefore, the best method of harvesting would be to use a three-funnel pyramid trap that does not have a bait well. The trap should be 30 inches high, have a 15-inch base, and be made out of black PCV-coated wire. The trap would also have a retainer ring made out of six inch thin-walled PVC pipe attached at the top opening. Fifteen to twenty traps per acre would be set out and baited with either fresh fish or manufactured bait on a Sunday evening. The traps would then be run the following Monday morning and rebaited, run Tuesday morning and rebaited, and then run Wednesday morning but not rebaited until the following Sunday evening.