Charles Lutz, Romaire, Robert P., Shirley, Mark G., McClain, W. Ray, Johnson, Richard | 5/25/2011 10:23:56 PM
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Now that we are on the downside of the production season for the state’s farm-raised crawfish crop, we are receiving inquiries from producers on stocking crawfish. With the exception of new ponds, one reason we have received many inquiries for information on stocking is because a number of crawfish producers did not have a good production year and there is a need to know whether or not adding additional broodstock can correct this problem.
Stocking usually is required only in new ponds, ponds that have been out of production (fallow) for a year or longer and when there has been a catastrophic loss of the crawfish population. Adding broodstock to ponds that have a residual population of crawfish, even if your yield was low and not sufficiently high enough to make money, usually is not advisable because crawfish have an ability, to a large extent, to self-regulate their population numbers. Only five pounds of female crawfish per acre (75 to 125 females, depending on size) that successfully burrow and produce young can potentially supply enough juveniles to produce a harvest of 800 to 1,000 pounds per acre. Stocking more crawfish will not necessarily result in a higher population of crawfish. Some producers mistakenly think that supplemental addition of larger broodstock will improve the genetics (gene pool) of the population, resulting in the production of larger crawfish. This is a fallacy. Genetics and selective breeding research with red swamp crawfish by LSU AgCenter scientists has shown that there is virtually no potential to increase crawfish size through genetics and breeding. Rather, harvest size is almost exclusively controlled by population density, food supply and water quality.
If stocking is warranted, then how much broodstock should you add? There are number of things that should be considered, including how much crawfish are already present in the pond, the projected survival rate of both those crawfish present in the pond and the additional stock we added, the success rate of reproduction and, of course, the expected survival rate of the young after hatching. Clearly, it is impossible to predict all these factors at the time of stocking.
Based on many years of research on crawfish reproduction and stocking, as well as years of experience and observations from commercial crawfish farming operations, below are current recommendations on stocking crawfish:
Stocking Recommendations for the 2011-2012 Production Season
If large acreages of ponds/fields are to be stocked, we recommend obtaining broodstock from several sources, stocking the crawfish over two to four weeks and stocking a good mixture of mature and immature sub-adults. Obtaining brood crawfish from several different ponds or suppliers reduces the risk of getting crawfish from a “stressed” source.
Individual farming operations might necessitate slightly higher or lower stocking rates. For example, if survival of the broodstock is anticipated to be low (such as from handling stress, predators, short flood duration, etc.) the recommended stocking rate can be increased by 1 1/2 times. For example, stock 60 pounds per acre rather than 40 pounds per acre. In contrast, if there is evidence of a healthy, but relatively low, resident population of crawfish in the pond, stocking rate may be adjusted downward by half. For example, stock 20 pounds per acre rather than 40 pounds per acre.
Encouraging Optimum Burrowing Conditions for Single-Crop (Permanent) Crawfish Ponds after Stocking
In rice-crawfish rotation systems, the most prominent production system in southwest Louisiana, crawfish are usually stocked in flooded rice fields after the permanent flood has been applied to the rice crop. Water is maintained at several inches until the field is drained for rice harvest. The stocked crawfish in rice-crawfish field rotations will construct burrows in levees at the water-levee interface when they are ready to burrow and free water is almost always available to help the crawfish in constructing the burrow. This is the optimal condition for successful burrowing.
However, in single-crop or “permanent” crawfish ponds, in which the same pond is used for crawfish production year after year, some additional recommendations should be followed.