Volume 61, Issue 338, May - August 2025

Estimates of life-history parameters and population dynamics of Bagrus docmak (Forsskål, 1775) in Lake Abaya, South Ethiopia

Buchale Shishitu Shija^♦

South Ethiopia Agricultural Research Institute, Arba Minch Agricultural Research Center, Ethiopia

^♦Corresponding Author
South Ethiopia Agricultural Research Institute, Arba Minch Agricultural Research Center, Ethiopia

ABSTRACT

Sufficient knowledge is necessary for the responsible exploitation of inland fisheries. However, many inland fisheries do not have adequate monitoring for sustainable fisheries management. The purpose of this study was to estimate life-history parameters and population dynamics of B. docmak from Lake Abaya. For the purpose collecting length-weight data, a total of 1033 fish were sampled from the commercial fisheries of Lake Abaya. SPSS and FiSAT II software were used to analyze the population dynamics and life-history parameters of the fish. The lengthweight relationship was estimated to be W = 0.0085L3.04; R2= 0.9118. The condition factor was highly significant by months’ interaction (P = 0.000), and had mean values of 0.99, 1.01, and 1.00 for females, males, and combined sexes, respectively. The estimated growth parameters were asymptotic length L∞ = 99.75 cm, growth rate K = 0.55 yr-1, theoretical age to = -0.21, growth performance index Φ′ = 3.74 and life-span tmax =5.24 years. The mortality related parameters were estimated as Z = 1.43 yr-1, M = 0.57 yr-1, E = 0.60, and Z/K = 2.6. The length at first maturity (L50), the length at first capture (Lc), and the optimum length (Lopt) were 52.02 cm, 44.27 cm, and 64.37 cm, respectively. The recruitment pattern was year-round, with biannual pulses in March and September. The length at first recruitment (Lr) and the corresponding age at first recruitment (Tr) were estimated to be 32 cm and 0.5 years, respectively. The study found that overfishing in recruitment and growth affected about 39.5% of the fish population. The exploitation rate (E) in the current investigation was 0.60, while the exploitation rate derived from Y΄/R for E0.5 was 0.35. Reducing the number of fishing gears is necessary for the management of B. docmak. In order to improve the sustainability of B. docmak in Lake Abaya, the current exploitation rate has been lowered by 42%.

Keywords: Condition factor, Exploitation rate, Growth pattern, Life-history parameters, Population dynamics

Discovery, 2025, 61, e23d3133

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DOI: https://doi.org/10.54905/disssi.v61i338.e23d3133

Published: 07 August 2025