Ecology and culture of Procambarus acutus acutus

Procambarus acutus acutus life cycle in South Carolina had two cohorts, carryover (CO) and young-of-the-year (YOY) crayfish, in culture ponds. Density decreased significantly from flooding through harvest. The YOY growth rate through the wet-culture phase (223 d) was 0.19 mm TL/d. Form-I males were present at a low level (4%) throughout the wet-culture phase. Length-weight regressions were significantly different among sex and sexual stages. Female from burrows during the dry-culture phase possessed significantly greater GSI and less hepatopancreas moisture values than females during the wet-culture phase. CO crayfish burrowed earlier and exhibited more advanced gonad development than YOY crayfish. Both cohorts oviposited eggs; however, only CO crayfish had attached instars. Pleopod eggs/female increased linearly with crayfish TL. Crayfish oviposited 96% of ovarian eggs in simulated burrows. The life cycle and single reproduction period limited the harvest population to one recruitment wave. In competition experiments P. acutus and P. clarkii YOY growth and survival in aquaria were similar through the fall-temperature (26–10°C) and winter-temperature (10°C) courses; however, P. acutus survived better and grew larger than P. clarkii over the spring-temperature course (10–26°C). Juvenile P. acutus starting with a mean size advantage in aquaria survived at a higher rate than P. clarkii whereas survival was similar when juveniles of the two species were the same size or when juvenile P. clarkii had a size advantage. At the start of the microcosm experiment YOY P. clarkii that were smaller grew slower than P. acutus through the experiment. Survival of YOY P. acutus was higher than P. clarkii when held together in microcosms. Juvenile P. acutus in microcosms grew faster than P. clarkii. Juvenile P. clarkii survival was lower in the presence of P. acutus than the conspecific. Estimated survival of 2200 P. acutus and 2200 P. clarkii YOY stocked in the 0.1-ha pond was 84% and 57%, respectively. YOY P. acutus and P. clarkii growth was 0.48 mmTL/d and 0.40 mmTL/d in the pond over 174 d. Body size advantage was important in defining competitive interactions between these two species.