Effects of stripping time on the success of the artificial incubation of white‐clawed crayfish, Austropotamobius pallipes (Lereboullet), eggs

Abstract

One of the main limiting factors in the use of artificial incubation techniques on crayfish farms has been the widespread belief that eggs should be stripped from females in the late stages of embryogenesis. In order to disprove this idea, three different times for egg removal were tested in white-clawed crayfish, Austropotamobius pallipes (Lereboullet): (1) just before the gastrulation process (mean degree days= 335, 34 days after spawning); (2) when the embryo was between the closing of the blastopore and the appearance of mandibular rudiments (mean degree days= 524, 56 days after spawning); and (3) when the embryo had thoracic appendage rudiments (mean degree days= 810, 92 days after spawning). The results showed that it is possible to attain acceptable survival rates up to juvenile stage 2 (51%), even when eggs have been detached at the earliest time (34 days after spawning), in such a way that artificial incubation is used for more than three-quarters (75.7%) of the total duration of the embryonic development. Factors such as the incubation device, water quality and incubation conditions have a major influence on the success of the process. Finally, a critical period was observed during the last stages of development in the present study, particularly between the eyed stage and juvenile stage 2, with mortality rates of between 26.7% and 56%.