Length-Weight Relationship and Condition Factor of Auchenoglanis occidentalis (VALENCIENNES, 1775) from Lake Akata, Benue State, Nigeria.

Abstract

A. occidentalis are economically important, highly valued and threatened freshwater fish species. To contribute to their ecological knowledge the Length-Weight Relationship and changes in the condition factor of A. occidentalis were analyzed from samples collected between May 2008-April 2009, in Lake Akata. A total of 770 fish specimens used for the study were obtained from fishermen operating on Lake Akata. These fishermen use various fishing gears including hand nets, cast nets and gill nets of various standard mesh sizes (20.2, 25.4, and 30.5mm).The aim was to supply basic information on the form of growth of the population of A. occidentalis, as well as to assess changes in the fish condition. The Length-weight relationship of fish was estimated from the equation: . b W a L  which was transformed to base 10 logarithm, and condition factor, (k) was determined using the equation: 3 K 100.W L  The mean weight and standard lengths of A. occidentalis, were 284.6(g)±6.9 and 25.34(cm)±0.36. The growth pattern of both male and femaleA. occidentalisin Lake Akata exhibited negative allometric growth pattern. The Length-Weight relationship equation for male and female of A. occidentalis was described by the equation: were LogW= - 1.1115 + 2.4729 Logl and LogW= - 1.1725 + 2.5029 Logl, respectively. The combined length weight relationship for both sexes was LogW = – 1.5644 + 2.8152 Log L. Fish species in the lake were generally in good condition. The mean condition factor for the combined sexes was 1.53±0.02, but individually, male A. occidentaliswere in better condition (1.53±0.03) compared to the females (1.52±0.03). There were no significant differences between the monthly condition factors of males and females of A. occidentalis (p>0.05). The wet season condition factor of A. occidentalis was higher than dry season values; The seasonal condition factor for A. occidentalis showed that there was no significant differences in the condition factor between dry and wet seasons (p>0.05).Lake Akata is a good environment for growth, reproduction and survival of the fish species