Population Dynamics of Chrysichthys nigrodigitatus (Lacépède, 1803) in a Tropical Man-Made Lake, Southwestern Nigeria

Background and Objective: The concern over probable loss of biological diversity and ecosystem function informed the updating of information on Chrysichthys nigrodigitatus population dynamics for sustainable management. This study, thus, aims to determine the population parameters of C. nigrodigitatus in Asejire Lake, Oyo State, Nigeria. Materials and Methods: Samples of the C. nigrodigitatus were obtained bi-monthly from Asejire reservoir landing sites between February and July, 2024. Total length (TL), fork length, standard length, and body weight (BW) were taken to precision. Length-weight relationships, condition factors, and growth parameters were estimated following standard methods. Mortality rate, longevity, and exploitation rate were determined using FSAT software. Data were analysed using descriptive statistics, multiple linear regression, and ANOVA at α_0.05. Results: The TL ranged from 13.55 to 40.30 cm with a mean at 24.41±0.31, while BW varied from 11.00 to 320.00 g. Length-weight relationships and condition factor were 2.93 and 0.51±0.13, respectively. The length at infinity (L∞), growth coefficient (k), longevity, and exploitation status were 36.07 (cm), 0.38 (year^–1), 3.5 (years), and 0.75 (>0.5), respectively. The total mortality, Z, was 2.54 year^–1, while natural mortality and fishing mortality were 0.67 and 1.91 year^–1, respectively. Conclusion: The growth coefficient revealed that the C. nigrodigitatus in Asejire reservoir is a fast-growing and short-lived species with an isometric growth pattern but a low condition factor. There is a need to improve the condition of the lake and adopt more sustainable management strategies to enhance the stock of C. nigrodigitatus in Asejire Lake, Nigeria.