Evaluation of body appendage injuries to juvenile signal crayfish (Pacifastacus leniusculus): Relationships and consequences

Abstract

Aggressive behaviour occurs frequently in crayfish and commonly results in injuries to body appendages. This study aimed to evaluate injuries to antennae, chelae, and walking legs of juvenile signal crayfish after seven months of rearing at high stocking density. We suggest that the high incidence of antennae injuries (66.8%) is related to their delicate structure and exposed position, which makes them vulnerable to damage. Chelae were more frequently injured (45.5%) than walking legs (7.8-23.6%). Considering the robustness of these structures and the scarcity of animals with both chelae missing and/or regenerating (4.9%), it seemed that injured animals were often killed by less injured ones. Antennae of crayfish with a single injured chela were more frequently injured on the side of the body with the damaged chela, and a similar pattern was observed for walking legs. Expanding on previous research reporting a negative relationship only between incidence of chela injury and crayfish size, we found this relationship to be significant for all evaluated appendages. We hypothesize that any injury and accompanying regeneration may have significant impact on subsequent injuries, overall growth, and reproductive success, and may result in death through cannibalism. © ONEMA, 2011.