Length-weight Relationships and State of Well-being of Parachanna obscura Gunther 1861, in Eleyele Reservoir, Southwestern Nigeria

摘要

The knowledge of length-weight relationship parameters has numerous practical applications in fishery researchand management. However, there is currently dearth of information on the growth pattern and state of well-being ofParachanna obscura in Eleyele Reservoir. This study therefore investigates the allometry and condition factor of P.obscura inhabiting the Eleyele Reservoir, Southwestern Nigeria. 688 specimens of P. obscura were collected fromartisanal fishers’ at their landing sites on a bimonthly basis for 24 months. Standard Length (SL, cm), and BodyWeight (BW, g) were measured. Length-Weight Relationships (b>3 or <3-allometric; b=3-isometric), and conditionfactor (K) were calculated using standard formula. Data were analysed using descriptive statistics and ANOVA atα0.05. The SL and BW of P. obscura ranged from 10.6 to 39.2 and 15.3 to 830.5 respectively. The LWR were 3.04(male) and 2.99 (female) indicating positive allometric pattern of growth in male and negative allometric growth infemale. The growth coefficient b ranged between 2.877 in July and 3.348 in May, with very significant coefficient ofdetermination r2 for all the months. Variations recorded in the b value of different size groups showed positiveallometric growth in 10.1 cm -15.0 cm, 15.1 cm -20.0 cm and 20.1 cm -25.0 cm, but negative allometric growth in25.1 cm -30.0 cm and 30.1 cm -40.0 cm. The maximum (1.54 ± 0.12) K was noticed during March 2016 and theminimum (1.30 ± 0.7) K in September 2015. Significant variation occurred in K with size groups. The mean K valuein females (1.43 ± 0.21 and 1.44 ± 0.20) was higher than males (1.40 ± 0.18 and 1.42 ± 0.17) for 2014-2015 and2015-2016, respectively. The results indicated that P. obscura were thriving very well in Eleyele Reservoir.