This finding serves as baseline for management of O. The fish was yet to complete 50-55% of growth as at the time of capture at Lc, L25 and L75 compared to L, hence, Lopt = 10.1 cm TL, provides least impact on the stock. The length-at-first capture Lc = 5.64 cm TL at age 1.7 yr. Results indicate the fishery is lightly exploited with current exploitation ratio, Ecur = 0.38 < Eopt = 0.5 rate of exploitation, μ = 0.3481 year-1 < Ecur, 35% of the available stock being fished annually corroborated by Z/K ratio (< 2) and M/K = 2.08, indicating environmental stability. The computed total mortality, Z = 2.54 year-1, natural mortality, M = 1.58 year-1 and fishing mortality, F was 0.96 year-1. The estimated growth performance index, φ′ = 2.444 based on length and φ = 0.6833, using weight. The von Bertalanffy exponential growth parameters were estimated as: asymptotic length (L∞) = 13.7 cm TL, growth curvature (K) = 1.48 year-1 and length-at-age zero years, t0 =-0.13 Lo = 2.40 cm TL. Three year classes with mean lengths of 7.4 cm, 11.55 cm and 13.3 cm TL, respectively, were identified. The length-weight relationship of the species indicated isometric growth (b = 3.005 r = 0.9623). The population dynamics of Odaxothrissa mento in the lower Cross River, southeast Nigeria, were obtained from a six month length composition data (4.25-14.75 cm TL mean = 5.91 cm ± 1.02 and 0.71-7.36 g 1.62 g ± 1.24 n = 1012).
