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Abstract
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Article Information:
Some Population Parameters of Distichodus rostratus (Gunther, 1864) from the Fresh Water Reaches of Lower Nun River, Niger Delta, Nigeria
J.F.N. Abowei
Corresponding Author: Abowei Jasper
Submitted: 2009 September, 11
Accepted: 2009 October, 30
Published: 2010 March, 10 |
Abstract:
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Some population parameters of Distichodus rostratus from the fresh Water reaches of lower Nun
River in the Niger Delta area of Nigeria, was studied for a period of one year (January, 2008-December 2008),
using five hundred specimens. The regression equation for the length weight relationship was Log
W = 0.0136+2.76 logL and correlation coefficient w as 0.976 at p<0.05. The regression equation for length
breadth relationship was Log M =1.60 Log TL and correlation coefficient was 0.968 at p<0.05. The largest
specimen measured 54.0 cm and weighed 442.8 g at age 5+. Growth increment in length (22.0 cm) was highest
in 1-2 years; while growth in weight was highest (141.5 g) in 2-3 years. The Maximum length at age attained
Lmax was 54.0 cm weighing 420.8 g. The length attained at infinity (L ∞) was 55.0 cm. Growth exponent (b)
was 2.76. Length performance index (θ1) value was 2.87. Weight performance index value (Ø) was 1.48.
Growth coefficient (K) value was 0.27. The hypothetical age at which length is zero (To) was –0.46 and the
maximum age estimated was 6 years. There was no temporal variation in the condition of the fish through out
the year with condition index value ranging from 0.96-1.00 and condition factor value of 0.98. Total mortality
(Z) value was 1.5 yr-1. Natural Mortality (M) value was 0.97; fishing mortality (F) value was 0.52. Value for
the rate of exploitation was 0.35 with corresponding percentage value of 30. Distichodus rostratus populations
from the fresh water reaches of the lower nun river was Lower than the optimal value for sustainable yield, for
the exploitation of the fishery; therefore stands the risk of under exploitation if urgent measures are not taken
to develop the fishery.
Key words: Age and growth, condition factor, Distichodus rostratus, mortality, Nun River, Nigeria,
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Cite this Reference:
J.F.N. Abowei, . Some Population Parameters of Distichodus rostratus (Gunther, 1864) from the Fresh Water Reaches of Lower Nun River, Niger Delta, Nigeria. Advance Journal of Food Science and Technology, (2): Page No: 84-90.
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ISSN (Online): 2042-4876
ISSN (Print): 2042-4868 |
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