Morphometry and sex ratio of four freshwater fish species in a Southwest Lake, Nigeria

Abstract :

The morphometry and sex ratio of Gymnarchus niloticus, Oreochromis niloticus, Hemichromis fasciatus and Coptodon zilli collected from Eleyele Lake were investigated. 627 samples obtained from May to September, 2018 were identified using standard guide and measured to the nearest gram and centimetre. Length-Weight Relationships (LWRs, b>3 or <3–allometric; b=3–isometric), condition factor and sex ratio were calculated using standard formula. Data were analysed using descriptive statistics, t-test and Chi-square at α0.05. The growth coefficient b of the LWRs indicated positive allometric growth in male and combined sexes of G. niloticus (b>3), and negative allometric growth in female. Male, female and combined sex of O. niloticus, H. fasciatus and C. zilli (b<3) also exhibited negative allometric growth. Condition factor ‘K’ values of all the species were greater than one (K>1) except G. niloticus indicating that all the fish species are in good physiological state of well-being in Eleyele Lake. Ratio of sex differed between species and showed significant variation from the expected ratio of 1:1 in G. niloticus only. This study provided useful information required for effective stock management of these four fish species in Eleyele Lake. However, the well-being of G. niloticus in the reservoir call for concern.

Keyword :

Inland fishery, allometrycondition factors, Eleyele Lake

Author(s) : Olanrewaju, A. N.
Downloads : 26
Published Issue : 2021 Vol. 16 Number 1

2021 Vol. 16 Number 1