Length-weight relationships and condition factors of Alestes baremoze , Brycinus nurse and Schilbe intermedius from the lower reaches of White Volta River (Yapei), Ghana

Abstract

A study to assess the length-weight relationships and the condition factors of 3 abundant and commercial fish species namely Alestes baremoze, Brycinus nurse and Schilbe intermediusin the lower reaches of the White Volta River (Yapei) was conducted from October 2011 to March 2012. Using W = aLb, the length-weight relationships of the species were calculated. Condition factors of the species were obtained using the formula: W*100/Lb. A total of 284 A. baremoze were measured with total mid length size range of 10.5 to 44.5 cm. A total of 197 B. nurse were measured and ranged from 6.5 to 27.5 cm total mid-length whereas 175 of S. intermedius were measured and had total mid length size range of 8.5 to 26.5 cm. The slope bof the length-weight relationships of the 3 species were within the acceptable range of 2.5 to 3.5 and can be used to approximate the weight for the 3 species in the lower reaches of the White Volta River. The condition factors variation of A. baremoze and B. nurse showed a pronounced change in December 2011, when the surface water temperature was lowest. S.intermedius had no significant changes in the condition factors over the study period. Key words: White Volta River, total mid-length, size range, species, surface water temperature.