Observations on the frequency of claw loss in the crayfish Procambarus clarkii

The incidence of claw loss in the crayfish Procambarus clarkii was surveyed in two ponds. Pond 1 contained rice forage, and crayfish were trapped and removed three times per week. Pond C48 contained no supplemental forage, an d no trapping occurred in the pond. In March claw loss in both ponds was si milar with 87-91% of the population having both claws intact. Males and fem ales showed no difference in the incidence of claw loss in either ponds. By May the abundant rice forage present in pond 1 during March had been deple ted; however, the physical appearance of pond C48 changed little. In May cl aw loss was greater in pond 1 than pond C48; both males and females in pond 1 had a higher incidence of claw loss (increasing from 13% to 37%) than th ose in pond C48 (increasing from 9% to 17%). Claw loss in pond C48 males di d not increase significantly; however, female claw loss increased approxima tely two-fold. In May hepatopancreas water content was significantly higher for crayfish from pond 1 when compared to pond C48, suggesting lower energ y reserves. During times of environmental stress, such as decreased food av ailability, decreased structure, low oxygen or temperature extremes, regene ration may influence energy allocation to growth and possibly reproduction, especially if energy reserves are low. Thus, information on the incidence of claw loss and energy reserves in crayfish exposed to different pond cond itions may be useful in the design of management strategies.