Duration of egg storage at different temperatures in the astacid crayfish Pacifastacus leniusculus:: critical embryonic phase

The critical phase that would limit duration of egg storage in the astacid crayfish Pacifastacus leniusculus was investigated. Weekly monitoring was conducted during an 84-day period of storage at three different constant temperatures (15.5 +/- 1,10.5 +/- 1.5 and 4 +/- 0.5 degreesC). After artificial incubation, stage 2 juveniles were only obtained from the lowest storage temperature, the sole treatment in which eggs did not reach the critical embryonic stage by the end of the storage. This limiting stage occurs at phase XII (embryo with pulsating heart) when embryogenesis of stored eggs ceased and phase XIII (eyed stage) was not reached. Eggs were also stored at a constant refrigeration temperature (4 0.5 degreesC) for periods ranging from 84 to 126 days. Mean survival rates to juvenile stage 2 were acceptable (approximately 50%) and different batches of juveniles were obtained over a 3-month period, depending on the duration of storage. The combined use of storage and artificial incubation techniques could have important applications to the development of astacid crayfish culture. (C) 2003 Elsevier Science B.V. All rights reserved.