Culture of the Australian red-claw crayfish ( Cherax quadricarinatus) in Israel : III. Survival in earthen ponds under ambient winter temperatures

The survival of the tropical crayfish Cherax quadricarinatus in earthen ponds under ambient winter temperatures was studied in the temperate zone in the central coastal plain of Israel. Four treatment groups in which sex and size were each tested at two levels were simultaneously run in four replicates over a period of 118 days (28 November 1996–26 March 1997). Minimum and maximum water temperatures were monitored every day, with minimum daily temperatures of under 10°C being recorded on six days. Overall survival was 60%; neither independent nor combined effects of sex and size on survival were found to be significant. Change in weight was minimal and few crayfishes entered baited traps, probably reflecting the reduced motor activity and feeding at low water temperatures. The economic implications of crayfish survival in earthen ponds under ambient winter temperatures, as well as the potential establishment of wild populations are discussed.