After flooding, crawfish
emerge from their burrows. The
farmer may choose to harvest
both rice and crawfish or only
crawfish. If the rice is harvested,
regrowth, called ratoon, occurs.
After harvest and as air temperatures
decrease to freezing, the
ratoon or the unharvested rice
dies and begins to decompose.
Bacteria and algae that grow on
decomposing plant material are
consumed by organisms that, in
turn, are food for the crawfish.
Crawfish can be harvested with traps as early as November, but are usually harvested from January through May. Harvest may end before May in response to a successful harvest from the capture fisheries or the need to plant a new crop. For a more detailed description of these production practices, refer to SRAC publications 240, 241 and 242.
Limitations of traditional culture
Culturing crawfish with planted
forage has helped to satisfy the
increasing consumer demand for
crawfish and to prolong the season
when crawfish are available.
However, when the harvest from
the capture fisheries is abundant,
prices often fall below the level at
which the culture fisheries can
realize a profit. Traditional crawfish
farming has other limitations.
The decay of vegetation in shallow
water can produce critically
low dissolved oxygen concentrations,
particularly when water
temperature is high. Also, food
resources are sometimes depleted
by mid-March or early April,
when the population of crawfish
is largest. As a result, crawfish
cease to grow, or become stunted,
and many of them remain below
Trapping is the only harvesting method that can be used in shallow water that contains vegetation. Seining is not possible when vegetation is present. Planted forage also limits the growth and harvest period. The pond must be drained and the crop allowed to grow before the pond can be reflooded. If flooding occurs when water is warm, accelerated rates of decay will cause the dissolved oxygen in the water to decrease to levels that are stressful or even lethal. If flooding happens when water is cool, water quality is not as likely to be a problem but the cooler water is not conducive to rapid growth of the red swamp crawfish.
An alternative culture
Growing crawfish in deeper ponds without planted forage has several advantages over traditional crawfish culture. The growing and harvest seasons are longer; there are fewer problems with low levels of dissolved oxygen; and deeper ponds without forage can be seined to rapidly remove excess crawfish and prevent stunted growth.
Pond design and water supply
Ponds should have an average depth of about 4 feet, range in size from 1 to 5 surface acres of water, and have a 3:1 slope from the top of the levee to the pond bottom. Long, narrow, rectangular ponds are more suitable than wide, square ponds because they make it easier to distribute feed or organic fertilizer over the entire surface area of the pond. There is also more space for crawfish to burrow along the perimeter of long, rectangular ponds. Narrow ponds also have a larger area of shallow water that presumably serves as a nursery or sanctuary for juveniles.
Either surface or ground water can be used to fill ponds. The lower cost of using surface water must be weighed against having a reliable quality and quantity of water. Surface water can contain predatory fish that compete with crawfish for the natural food in the pond. Once ponds are filled, additional water is needed only to replace what is lost from evaporation. Ponds are generally not drained unless they become contaminated with fish.
After the pond is prepared and
filled, it is stocked with broodstock
obtained from commercial
capture or culture fisheries.
Stocking can be done from May to
July. Broodstock generally consists
of an equal number of males and
females. Stocking density should
be 75 to 100 pounds per acre (84
to 112 kg/hectare). Be sure to
stock only crawfish harvested
within the previous 24 hours.
Crawfish held for longer periods of time are subject to stress and may have significant post-stocking mortality. Broodstock should be transported in mesh sacks and packed densely enough to minimize movement. The transported crawfish should be kept cool and moist, but not have direct contact with ice. If sound management practices that ensure good survival are followed, crawfish should not have to be restocked annually. The unharvested population remaining in the pond should be sufficient to sustain consistent levels of production from year to year. Restocking is recommended when annual production in a pond is significantly lower than in all other ponds or when it decreases by 25 to 30 percent over time. Broodstock should be restocked at a rate proportional to the decrease in production.
Feeds and feeding strategies
Existing ponds do not need to
have a food source added before
stocking because natural foods
should be sufficient to sustain the
population until the first young of
the year (those hatched during
successive spawnings of a calendar
year) are produced in mid-fall.
However, new ponds should be organically fertilized (with cracked corn, cotton seed meal, or distillers dried grains) before and after stocking to ensure sufficient natural food. Once the initial young of the year have hatched, a formulated feed (a combination of organic fertilizer and feed, or just a fertilizer) must be added to the pond to enhance the production of pond organisms. Both a pelleted, 32% crude protein, sinking catfish feed and a comparably priced extruded, 28 to 30% crude protein, sinking diet have been successfully used in experimental trials. The food breaks up rapidlybefore it is consumedso it mainly acts as a fertilizer and a source of nutri- tion for microorganisms that, in turn, are food for those organisms crawfish eat. For direct consumption by crawfish, it is best to use a highly water-stable, extruded, formulated feed.
If the price of feed becomes costprohibitive, alternative methods of fertilization will be necessary. For example, two-thirds of the amount of a sinking catfish feed might be replaced with alfalfa or range pellets. Or, commercial feed could be supplemented with or replaced by an organic fertilizer such as corn, alfalfa hay, cottonseed meal, or soybeans. In recent research, a combination of rejected soybeans and alfalfa hay (composite level of crude protein = 28%) was substituted for formulated feed with no significant differences in production.
The recommended feeding (fertilization) rates for each month are presented in Table 1. These amounts translate into daily feeding (fertilization) rates of 5.6 to 31.5 pounds per acre (6.3 to 35.3 kg/hectare). These are estimates based upon the biomass (total weight) of the pond population and the water temperature. Crawfish eat less as water temperature decreases and eventually stop eating at temperatures less than 50 F (less than 10 C), within its range of tolerance. Crawfish feed and forage most actively during the evening. However, because feeding is essentially a pond fertilization process, it should be done in mid-afternoon when the level of dissolved oxygen is comparatively high. Whether feeding (fertilization) needs to be done every day has yet to be established.
There are many fertilizers, in a range of prices, that could be used. Pelleted feed is easier to distribute than feedstuffs. Pelleted organic fertilizers include corn gluten, rice bran, alfalfa pellets and range pellets. Organic fertilizer should be used with care, however, particularly if the temperature of the water is high, because it can dramatically reduce dissolved oxygen.