Research Journal of Biological Sciences

Year: 2009
Volume: 4
Issue: 3
Page No. 282 - 288

Some Morphormetric Parameters of Ten Finfish Species from the Lower Nun River, Niger Delta, Nigeria

Authors : .F.N. Abowei and A.I. Hart

Abstract: The morphormetric parameters: length-breadth relationship, growth, mortality and exploitation rate of 10 fish species from the fresh water reaches of the lower Nun river was studied for a period of 2 years, using different fishing gear. All species exhibited positive allometric growth (J>1) with growth rate values (J) ranging from 1.06 (Parailia pellucida) to 1.67 (Synodontis membranaceus) except Sphyraena barracuda, which exhibited negative allometry (J<1) with growth rate values of J = 0.73. The correlation coefficient (r) values ranged from 0.957 (S. membranaceus) to 0.994. (P. pellucida). “r” values were positive for all species studied. The length attained at age (Lmax) ranged from 12.5 cm (P. Pellucida) to 59.1 cm (Clarotes laticeps) weighting 99.5 and 491.0 g, respectively. The length attained at infinity L∞ ranged from 13.2 cm (P. Pellucida) to 60.0 cm (C. laticeps). Growth exponent ranged from 2.63 (S. membranaceus) to 3.23 (P. Pellucida). Length performance index (ø1) ranged from 2.34 (brycinus baremose) to 3.23 (Synodontis clarias). Weight performance index (ø) values ranged from 1.48 (Distichodus rostratus) to 2.97 (S. clarias). Growth coefificent (k) values ranged from 0.26 (Brycinus dentex and Brycinus baremose) to 0.64 (Synodontis schall). The hypothetical age at which length is zero (To) values ranged from-0.2yr-1 (B. dentex) to-1.05 (S. clarias). The maximum age estimated (Tmax) ranged from 3 (P. pelluada) to 6 years (D. rostratus). Total mortality (Z) values ranged from 1.1yr-1 (B. baremose) to 2.1yr-1 (S schall). Natural Mortality (m values ranged from 0.55 year-1 (P. pellucida) to 1.82yr-1 (S. schall). Fishing mortahty (F) values ranged from 0.17yr-1 (B. baremose) to 0.87 year-1 (P. pelluada) values for the exploitation rate (E) ranged from 0.11yr-1 (B. baremise) to 0.67 year-1 (P. pellecida) with corresponding percentage values of 11 and 45. The study revealed that S. clarias, S. barracuda and P. Pellucida with exploitation rates of 0.54, 0.54 and 0.67, respectively exceed the optimal value for sustainable yield for the exploitation of the fishery. Therefore these populations stand the risk of over exploitation in the lower Nun River, if urgent measures are not taking to protect their fisheries.

How to cite this article:

.F.N. Abowei and A.I. Hart , 2009. Some Morphormetric Parameters of Ten Finfish Species from the Lower Nun River, Niger Delta, Nigeria. Research Journal of Biological Sciences, 4: 282-288.

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