Growth and survival of Procambarus acutus acutus (Girard, 1852) and P. clarkii (Girard, 1852) in competitive settings

Third-instar young-of-the-year (YOY) and juvenile Procambarus acutus acutus and P. clarkii stocked in aquaria, rice forage microcosms and a culture pond were evaluated in intraspecific- and interspecific-competitive settings. Procambarus acutus acutus YOY, which were larger than P. clarkii YOY at stocking, grew and survived at significantly greater rates over fall-, winter- and spring-temperature courses in aquaria. Juvenile P. a. acutus starting an aquarium experiment with a mean total length (TL) size advantage survived at a significantly greater rate than P. clarkii juveniles. Growth rate of similar-sized stocked P. a. acutus juvenile was significantly faster than that of P. clarkii juveniles in the same microcosms. Survival of juvenile P. clarkii in the microcosms with P. a. acutus was significantly less than when stocked alone. Estimated survival of 2200 P. a. acutus and 2200 P. clarkii YOY in a culture pond over a 174-day grow-out period was 84% and 57% respectively. Growth rate of these YOY P. a. acutus and P. clarkii was 0.48 and 0.40 mm TL day(-1). The body-size advantage at hatching and through the faster growth of P. a. acutus was important in defining competitive interaction with P. clarkii.