On the life history of a cyprinid fish, Labeo cylindricus

Aspects of the life history of Labeo cylindricus in Lake Chicamba, a wan ma de hydroelectric dam in central Mozambique were investigated. L. cylindricu s was found to be a potadrometic, synchronous spawner concentrating in rive r mouths prior to migrating up flowing rivers in January to spawn. Length-a t-(50%)-maturity was attained at a fork length (FL) of 96 mm for males and 98 mm for females, both within their first year of life. The adult sex rati o was found to be female dominated at 1 male:1.63 females. Scales were used to age the species, with two growth checks deposited annually. Growth was rapid and was best described by the von Bertalanffy growth model as L-t = 2 24.2(1 - e(-0.66(t+0.03))) mm FL. A maximum age of 4 years was observed for L. cylindricus with the largest male and female measuring 210 mm FL and 23 5 mm FL, respectively. The rate of natural mortality was estimated to be ex tremely high at 1.93 year(-1) using length-converted catch curve analysis a nd is possibly a response to heavy predation by the introduced piscivore Mi cropterus salmoides.