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Vol.4 , No. 1, Publication Date: Jan. 18, 2018, Page: 32-39
 in the mid-Cross River basin was studied. Monthly samples were collected from commercial artisanal fishermen from July 2011 to June 2012. The FAO-ICLARM Stock Assessment Tool (FiSAT II) software was used for data analysis. Growth parameters for <i>C. nigrodigitatus</i> were as follows: asymptotic length L<sub>∞</sub> = 29.93 cm TL and growth curvature K = 0.18 yr<sup>−1</sup>. The mortality parameters for <i>C. nigrodigitatus</i> were: total mortality Z = 0.86 yr<sup>−1</sup>, natural mortality M = 0.59 yr<sup>−1</sup>, and fishing mortality F = 0.27 yr<sup>−1</sup>. <i>C. nigrodigitatus</i> exhibited a bimodal recruitment pattern. Length at first capture (L<sub>c</sub>) was 12.22 cm TL. The selection ogive procedure for relative yield and biomass per recruit showed that E<sub>max</sub> was 0.59 for <i>C. nigrodigitatus</i>. The stock was not overexploited, since E < E<sub>max</sub>. The exploitation rate (E) was 0.32 and given that E < 0.50 is considered to be moderately exploited for the fishery. However precautionary management is needed as the M value is high.&picture=http://www.aascit.org/aascit/decorators/img/journal/897.jpg)
| [1] | Uneke Bilikis Iyabo, Fisheries Biology Unit, Department of Biological Sciences, Faculty of Sciences, Ebonyi State University, Abakaliki, Nigeria. |
Stock assessment involves the application of statistical and mathematical methods to make quantitative statements about the status of fished populations and predictions about how they are likely to respond to alternative management choices, thus the stock assessment of Chrysichthys nigrodigitatus (n = 470) in the mid-Cross River basin was studied. Monthly samples were collected from commercial artisanal fishermen from July 2011 to June 2012. The FAO-ICLARM Stock Assessment Tool (FiSAT II) software was used for data analysis. Growth parameters for C. nigrodigitatus were as follows: asymptotic length L∞ = 29.93 cm TL and growth curvature K = 0.18 yr−1. The mortality parameters for C. nigrodigitatus were: total mortality Z = 0.86 yr−1, natural mortality M = 0.59 yr−1, and fishing mortality F = 0.27 yr−1. C. nigrodigitatus exhibited a bimodal recruitment pattern. Length at first capture (Lc) was 12.22 cm TL. The selection ogive procedure for relative yield and biomass per recruit showed that Emax was 0.59 for C. nigrodigitatus. The stock was not overexploited, since E < Emax. The exploitation rate (E) was 0.32 and given that E < 0.50 is considered to be moderately exploited for the fishery. However precautionary management is needed as the M value is high.
Keywords
Growth, Mortality, Recruitment, Relative Yield and Biomass Per Recruit, FiSAT II, Chrysichthys nigrodigitatus
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