Journal of Animal and Plant Sciences
J. Anim. Plant Sci. [ISSN 2071 - 7024]
Volume 5 (2): 531 - 538. Published December 29, 2009.
Population Parameters of Clarias gariepinus (cat fish) in Gubi dam, Bauchi State,Nigeria.
Abdulkarim, M*^, Yusuf Z.A*, Musa B.L** and Ezra A.G**
*Animal Production Programme and **Biological Sciences Programme
Abubakar Tafawa Balewa University Insert PMB 0248 Bauchi, Bauchi State, Nigeria.
SUMMARY
Studies on the population parameters of Clarias gariepinus (cat fish) in Gubi dam, Nigeria was carried out to determine the curvature parameter, asymptotic length, mortality rates and exploitation rate of the fish in the dam. Length-frequencies data of 272 Clarias gariepinus obtained from six fishermen ranged from 8 – 41cm (total length to the nearest cm. Selection ogive curve was used to adjust length-frequencies data for the interphase months from which monthly catches from January to December, 2008 were estimated using proximate catch and population analysis (PCPA). The assessment revealed that asymptotic length (L∞) = 43cm, growth coefficient (K) = 0.65/year, growth performance (Ф) = 3.08, age at zero length (to) = -1.37 years and natural, fishing and total mortality rates were found to be 1.20/year, 0.22/year and 1.42/year, respectively. Over 88 % of the landings were below minimum exploitable sizes (L opt = 27cm) and for that “close area” (spawning ground) fishing far from the spawning grounds is recommended. Increase of current fishing effort (7300 man days/year) by 29 percent will enable the fishermen attain maximum sustainable yield (MSY) of 16.53 tons compared to current yield of 12.81 tons per annum, this can be achieved if the policy makers enforced the minimum legal length (Lg) of 15cm. of the fish to be caught in the dam.
Key words: Selection ogive, Interphase months, Mortality rates, asymptotic length
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