Artificial incubation of the eggs of the crayfish Austropotamobius pallipes (Lereboullet)

Abstract

In Great Britain, incubation time for eggs of the native crayfish, Austropotamobius pallipes, is approximately 9 months, with hatching occurring in May and June in Midlands waters. Artificial incubation at higher than ambient temperature would possibly reduce this time and make juveniles available for stocking in early spring. To test this hypothesis, fertile eggs were removed from the pleopods of ovigerous females maintained at ambient temperatures at different times (30-day intervals from late November through late April) and incubated in flowing water baths at 7 ± 1°C, 13 ± 1°C and 18 ± 1°C. Only eggs stripped from females from late January–April survived to hatching in the artificial incubation system, and none survived at 7 ± 1°C. However, incubation at 13 ± 1°C and 18 ± 1°C produced large numbers of juveniles as early as March and April. Overall, 13 ± 1°C was the best incubation temperature, considering both survival to hatching (average of 72% from February through April) and early development of the hatchlings. Daily dosing of the eggs with malachite green (10–20 ppm) eliminated fungal infections from the artificial incubation systems.