地理ジャーナルと自然災害
オープンアクセス

概要

Studies on the Biology of Synodontis victoriae in the Nyanza Gulf of Lake Victoria, Kenya

Edwine Yongo* and Alex Wairimu

Fish samples (401) were collected weekly between May to July 2015 from commercial catches in the Nyanza Gulf of Lake Victoria, Kenya. The Fork length (cm FL), weight (g) and sex were determined. A total of 288 (71.8%) were female while 107 (26.7%) were males, sex ratio; 1.0:2.7 (male: female). Size of females ranged from 9.0 cm to 17.6 cm FL, mean (± SD) 13.6 cm ± 1.3 cm FL and weighed between 13.0 g and 99.0 g, mean 47.5 g ± 13.9 g. Length of males ranged from 7.0 cm to 15.6 cm FL, mean 12.8 cm ± 1.3 cm FL and weighed between 7.0 and 62.0 g, mean 36.2 g ± 9.9 g. Sex dimorphism was observed as female fish were significantly larger than males (p<0.05). The length frequency showed a unimodal distribution with modal class at 13 cm FL. Male, female and both sexes showed negative allometric growth pattern (b<3). The fish had a good condition with values equal to 1. The smallest mature male and female fish were 11.2 cm and 11.3 cm FL, respectively. The length at 50% maturity was estimated at 13.0 cm FL for male and 12.0 cm FL for female fish. The study has thus provided baseline information on some aspects of the biology of Synodontis victoriae that are limited in the lake.