Harvest generally begins in late March or early April of the year following initial stocking.
Trapping is the principal harvest method, but seining can be done when conditions warrant. In deep ponds, boats are needed for efficient trapping.
Boats should be able to maneuver among substrate (see section on substrate). Commonly used traps are pyramidal in shape, with a 3/ 4-inch hexagonal mesh and three openings around the base (Fig. 1).
Almost all new traps have a 3/ 4-inch square mesh that retains smaller crawfish. The neck of the trap extends above the water and is equipped with a PVC collar to prevent crawfish from escaping.
Traps can be held upright by inserting a rebar vertically through the trap. Using 20 to 25 traps per acre (49 to 62 per hectare) is recommended.
The schedule for baiting and harvesting traps is based on water temperature. There are many brands of formulated bait made for use in traps.
Formulated bait is most effective when the crawfish are most active, generally at water temperatures of 66 to 86 °F (19 to 30 °C). Below 66 °F (19 °C), harvest is not significantly different whether formulated bait is used or not. This may be because at lower temperatures crawfish seek refuge in traps.
When water temperature falls below 66 °F, traps can be set without bait and harvested once per week. A cost effective catch without bait at temperatures below 66 °F might be achieved by using more traps.
At water temperatures higher than 66 °F (19 °C), baited traps are harvested three or four times per week, depending on the time of year. The interval between baiting and harvest is generally 24 or 48 hours. Several examples are shown in Table 2.
For example, if traps are harvested four times per week, there would be one 24-hour and three 48-hour intervals. If traps are harvested three times per week, there would be two 48- hour and one 72-hour intervals.
The harvest schedule should maximize catch. Variables that affect catch per trap per day (i.e., catch per unit effort or CPUE) include water temperature, water quality, moon phase, weather patterns, and population density. Trap harvest should be suspended when water temperature falls below 59 °F.
Trap harvest should be suspended for at least 1 week when the average weekly CPUE falls below 0.5 pounds per trap per day. The CPUE begins to decline about August 15 when the peak period of mating and spawning occurs. Trap harvest may need to be suspended periodically after that date. This period in the harvest season may vary with the latitude of the production ponds.
Trap harvest may resume again in late September or early October. Basing harvest on temperature and CPUE generally results in 75 to 90 harvest days per year, or 20 to 30 weeks per year. These recommended harvest practices optimize CPUE by reducing labor costs and may help increase the average individual size (weight) of harvested crawfish.
Approximately 70 percent of the total trapping days occurs from April through August in northeast Mississippi (Table 3). The duration of the trap harvest season and the number of trap days are influenced by latitude. Monthly yields are based upon the number of trap days per month. Daily yield is highest from March through July, rang ing from about 25 to about 40 pounds per acre per day (28 to 45 kg/hectare/day).
When conditions from August through February are favorable for harvest, the daily yield decreases by approximately 50 percent and ranges from 10 to 25 pounds per acre per day (11 to 28 kg/hectare/day).
The number of trap days in March, April and May can be reduced and offset by trapping more days during August, September and October without lowering the total biomass harvested annually.
The increase in labor might be offset by higher prices obtained during this period when ponds with planted forage are drained. It might be possible to get higher daily yields for the latter months, when water temperature usually declines below 66 °F (19 °C), by using a “cold water” formulated bait rather than unbaited traps.
Fish make good cold water bait in traditional forage- based farming; however, using fish can cause problems related to labor, availability, storage and the introduction of disease. Crawfish can be harvested by seining when the water temperature is below 66 °F (19 °C).
However, there is little difference in total weekly yield between seining once per week and harvesting unbaited traps several times per week. Seining will capture recently molted or soft-shell crawfish that do not enter traps (although seining can damage their delicate shells).
Soft-shell animals are a value-added product and usually command a much higher price. Soft-shell crawfish must be separated from other crawfish and processed rapidly to preserve the soft-shell condition.
Authors:
Louis R. D’Abramo, Cortney L. Ohs, Terrill R. Hanson and Jose L. Montanez
