Invasive Australian crayfishCherax quadricarinatusin the Sanyati Basin of Lake Kariba: a preliminary survey

The invasion of Cherax quadricarinatus, the Australian redclaw crayfish, in the Sanyati Basin of Lake Kariba, Zimbabwe, is reported. A total of 79 crayfish were caught at 10 out of 12 sampling sites in the Sanyati Basin in November–December 2012. The average catch per unit effort (CPUE) varied from 1.1 to 4 crayfish per trap per night, carapace length ranged from 29 to 93.5 mm, and weight ranged from 4 to 196.2 g. Most crayfish were between 50 and 59.9 mm carapace length. Males (average 82.6 g) were significantly heavier than females (37.2 g) and males were larger in carapace length, carapace width, chela length and chela width. A feral population of C. quadricarinatus is now established in the Sanyati Basin. Possible modes of dispersal within the basin are discussed.