Metals in Crawfish - Aquaculture and the Environment: A Shared Destiny - page 199

source for insects, worms, snails and some small vertebrates that then consumed by the
crawfish. These organisms provide high quality nutrition for crawfish.
Supplemental feeds are not often utilized in Louisiana crawfish aquaculture ponds. The
primary means of providing nutrition to crawfish in aquaculture is by establishing and
managing a forage crop in the crawfish ponds. Once the ponds are flooded in the fall the
forge crop and detritus produced by it must provide a constant and continuous supply of
nutrients for the food web on which the crawfish relies for its nutrition.
3. Crawfish aquaculture ponds
3.1 Location and layout
Ponds are located in open flat areas in soils with a sufficient amount of clay in the soil. Soils
that can be shaped into a ball have enough clay to be suitable. The clay content is important
to hold water during flooding and to maintain the integrity of the crawfish burrows. Water
resources for periodic flooding of the ponds are also necessary. The pond must be at an
elevation above the water levels of surrounding canals and ditches. On farms where
crawfishing is rotated with rice crops, several factors need to be considered. Ponds must
have adequate all-weather access because aquaculture of crawfish requires almost daily
harvesting and pond management during the January through June harvesting period.
Because crawfish farming is labor intensive, only 10 to 50 percent of a farmer's rice acreage
will be selected for crawfish aquaculture. Farmers usually do not rotate the best rice
producing fields with crawfish farming.
There is no standard size for a crawfish pond. A size range of 10 to 40 acres is prevalent in
Louisiana. Most crawfish producers manage fewer than 150 total acres. For the purpose of
trapping, long fields with few levee crossing are the most efficient. Consideration must be
given to other nearby farming operations where the aerial application of pesticides may
contaminate downwind crawfish ponds.
3.2 Design and construction
Whether constructing a pond for permanent crawfish production or using an existing rice
field for rotation with crawfish, many considerations need to be taken into account. The
perimeter levees should be 3 meters wide at the base to prevent leakage from crawfish
burrowing. Levees that are 1 meter tall are adequate to maintain the minimum of 20 to 25
centimeters of water necessary for crawfish production. The fall of the land should not
exceed 15 centimeters between levees. Fields with steeper grades result in water depth
variations that hamper forage growth and reduce harvesting efficiency. Drains for the field
should be sized based on field size, projected rainfall and irrigation pumping capacity. One
25 centimeter diameter drain is sufficient per 10 acres of pond. Interior levees within the
pond should be 2 meters at the base and be 15 centimeters above the water level in the pond.
These interior levees should be spaced 50 to 100 meters apart to facilitate water circulation.
Wide or deep interior ditches should be avoided if possible. These ditches provide the least
resistant flow of water within the pond which can lead to poor circulation in the rest of the
pond. Poor circulation of water can lead to stagnation of the water and cause lower
production of crawfish. Deep areas within the field will also make periodic draining the
fields difficult.