Metals in Crawfish - Aquaculture and the Environment: A Shared Destiny - page 202

production does not take place in the same ponds from one year to the next. In the first
mentioned rotation method, the field will be left fallow for a year following the crawfish
harvest. Under the second method of rotation, if soybeans or another crop is planted after
the crawfish harvest, then three crops per field can be harvested in a two year time frame.
These two approaches require sufficient acreage to allow staggered crops in different fields
within the farm. This rotational method is used on much of the acreage used in crawfish
aquaculture in Louisiana because it has advantages over rotation within the same field. Each
of the crops in this type of rotation can be better managed because each crop has the
necessary time to maximize growth and harvest. Specifically for crawfish production, the
crawfish ponds do not have to be drained in late spring to rice. This yields a lengthening of
the crawfish harvest season into early summer because soybeans or other crops can be
planted later in the year. The disadvantages of this rotation system include: the need to re-
stock crawfish each year, lower population densities and the late season harvest frequently
is frequently plagued by low market prices for the crawfish.
5. Stocking
5.1 General guidelines
Crawfish farming relies on reproduction of the resident adults to sufficiently populate the
ponds for each harvest. Established ponds seldom have a need to be re-stocked because the
crawfish that remain after the harvest serve as brood stock for the next year. Stocking is
usually only necessary in: 1) new ponds, 2) after a fallow year or crop rotation other than
rice, 3) after severe drought or 4) after extensive levee renovation.
5.2 Stocking considerations and procedures
Red swamp crawfish is the preferred species for stocking because of their longer
reproductive season. The size of the mature broodstock is of little concern, because even
though large crawfish produce a higher number of offspring, there would be fewer of them
per purchased kilogram of crawfish. The time for stocking depends upon the reason for
stocking. April to July is the best time to stock a new pond in a monocropping system or
restock a pond at has skipped a season. When re-stocking a rice field, stocking should be
done about 45 days after planting when the rice plants are large enough to withstand the
crawfish without damage and when the need for harmful pesticide applications have
passed. Careful handling of the broodstock from trapping to release is important. Keeping
the crawfish clean, moist, and at temperatures around 20º C. This is best accomplished by
avoiding direct sunlight, wind, and by covering the sacks of crawfish with wet tarpaulins or
burlap sacks. When stocking, crawfish should be dumped directly in the water. Because
crawfish are mobile, there is no need to equally spread them over the entire pond. The
crawfish should however be stocked in each section of a large pond. The temperature of the
pond being stocked should not differ greatly from the temperature of the crawfish
themselves at the time of stocking. Stocking rates of 25 to 30 kg/acre is generally
recommended but many farmers stock up to 40 kg/acre if post-stocking survival is
unpredictable. The female population should exceed 50 percent because a male crawfish can
mate with more than one female. Survival rate of the broodstock is extremely important to
the stocking process. Water temperature, dissolved oxygen levels and water levels in the
stocked pond must be maintained.