The Frequency of Chela Autotomy and Its Influence On the Growth and Survival of the Crayfish Procambarus Clarkii (Girard, 1852) (Decapoda, Cambaridae)

Abstract

We investigated chela autotomy in young of the year crayfish, Procambarus clarkii (Girard, 1852), from two perspectives. We wished to determine (1) the influence of crayfish density and refuge availability on the frequency of crayfish chela autotomy, and (2) the impact of chela autotomy on the growth and survival of crayfish reared at low and high densities and in low and high refugia levels. A 13.1 % of surviving crayfish were observed with at least one chela missing. There was a greater percentage of crayfish with a chela missing in tanks stocked at high density (18.1%) compared to crayfish stocked at low density (8.2%). There were no differences in the percentage of crayfish missing a chela in tanks with low (16.3%) and high (10.0%) refugia. The percentage of chela loss in males (15.8%) was higher than in females (10.5%) especially at high density (males = 24.5%; females = 1 1.6%; low density: males = 7.1 %; females = 9.3%), however, these differences were not statistically significant. Survival of crayfish was significantly reduced in the high density treatment compared to survival of crayfish in the low density treatment. Survival rates through time were significantly reduced for crayfish with chelae removed in the high density compared with survival rates of crayfish with chelae removed in the low density, and survival rates of non-injured crayfish stocked at low and high densities. Crayfish with chelac removed were significantly smaller than non-injured crayfish at the end of the experiment. Crayfish body size was not influenced by density or refugia. We discuss how reduced growth and survival rates resulting from chela autotomy can influence crayfish population dynamics.