The relationship between crayfish pond size and crayfish (Procambarus spp.) production (O)
HUNER, Jay V.
Crawfish Research Center, University of Southwestern Louisiana, Lafayette, Louisiana 70504-4650, USA

Crayfish (Procambarus clarkii and Procambarus zonangulus) are cultivated in the southern USA by establishing self-perpetuating populations after
initial stocking with adult crayfish. Ponds are drained during the warm months and refilled during the cool months. Crayfish persist and reproduce in
simple tubular burrows 1.0-1.5 m in depth. Most successful burrows are located at the surface-water interface around pond perimeters. Therefore,
there will be more burrows per unit of surface area in smaller ponds than in larger ponds. Crayfish have been harvested for 8 consecutive seasons
(1990-91 to 1997-98) from three 2.0 and two 4.0 ha pond units in south-central Louisiana. Mean harvests have ranged from 790-1,010 kg/ha from
the smaller units to 430-570 kg/ha in the larger units. Because crayfish growth is density dependent, the larger units have consistently generated the
largest crayfish.
 

Effects of hypoxia on growth and survival of the crayfish Procambarus clarkii (O)
McCLAIN, W. Ray
Rice Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, P.O. Box 1429, Crowley, Louisiana
70527-1429, USA

Dissolved oxygen (DO) is repeatedly referred to as one of the most important factors affecting crayfish production; however, little is known of the
effects of hypoxia on Procambarus clarkii. This study investigated some of those effects. Two 12-week trials were conducted in replicated 38-l
flow-through tanks supplied with soil, established vegetation, and pond water to provide micro-habitats that simulated pond culture environments.
Young crayfish (= 1.2 g) were individually stocked and represented a density of 12 crayfish/m². Standing rice substrate provided the forage base and
was allowed to fragment naturally. Supplemental aeration was either provided or withheld to establish the treatment factors in Experiment 1. Those
treatments were repeated in the second experiment, along with three others (7 hours of aeration every other week; aeration for the first 6 weeks
followed by no aeration for 6 weeks; vice versa). Dissolved oxygen values in aerated habitats were > 6 mg/l, and values in non-aerated containers
generally remained below 0.5 mg/l. Crayfish exposed to prolonged hypoxia, although adversely affected, performed remarkably well. Survival was
highest in aerated groups but was = 60% for all treatments. Final weights in Experiment 1 averaged 14.5 and 12.2 g for the aerated and non-aerated
treatments, respectively. Crayfish in the second experiment averaged 6.8, 7.4, 9.7, and 11.6 g for the non-aerated, biweekly aerated,
aerated/non-aerated, non-aerated/aerated, and aerated treatments, respectively.