The Common carp, Cyprinus carpio is an exotic fish in Lake Naivasha. It is one of the commercially important species in the lake. This study investigated on its biology and population parameters during 2017. Fish samples (433) were caught using gillnets of mesh-sizes 2-5 inches. Length of fish ranged from 12.0 to 69.0 cm TL, and weighed between 32 and 6840 g. The overall population sex ratio was 1.66: 1.0 (male: female). The mean length of females was 34.8 cm and males 32.1 cm. The length at first maturity was calculated at 54.0 and 49.0 cm for females and males, respectively. The mean condition factor for all fish was 1.05. The peak condition values were recorded during April (1.35), September (1.59) and October (1.80). There was a significant difference in mean condition factor within the size classes highest (1.38) and lowest (0.93) values recorded in class 56-60 and 26-30, respectively. The overall asymptotic length (L∞) was 73.5 cm and growth curvature (K) 1.05 yr-1 with growth performance index (Ф) of 3.72. The total (Z), natural (M), fishing (F) mortality coefficients 2.85, 1.34 and 1.78 yr-1, respectively. The exploitation rate (E) of 0.57 was higher than optimum sustainable yield (E0.5) of 0.32, but not different from maximum sustainable yields (Emax) 0.54 and economic yield (E0.1) 0.46. The length at first capture (LC50) was lower than length at first maturity (LM50), suggesting capture of immature fish. This study provides parameters of fish biology and population often useful in fisheries management.
Aspects of the Population biology of Common Carp, Cyprinus carpio (Linnaeus, 1758) In Lake Naivasha, Kenya
