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Abstract
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Article Information:
Aspects of Hemisynodontis membranaceus (Greffroy-st Hilare, 1809) Population Dynamics from the Fresh Water Reaches of Lower Nun River, Niger Delta, Nigeria
J.F.N. Abowei
Corresponding Author: Abowei Jasper
Submitted: 2009 Sept., 11
Accepted: 2009 Oct., 07
Published: |
Abstract:
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Age and growth and mortality study of Hemisynodontis membranaceus from the fresh Water reaches
of lower Nun River in the Niger Delta area of Nigeria, was studied for a period of one year(Jan. –Dec. 2008),
using five hundred specimens. The regression equation for the length weight relationship was Log W =
0.0157+2.86logL and correlation coefficient was 0.966 at P<0.05. The regression equation for length breadth
relationship was Log M =1.67 Log TL and correlation coefficient was 0.957 at P<0.05. The largest specimen
measured 41.7cm and weighed 341.5g at age 4+. Growth increment in length (12.0cm) was highest in 1-2 years;
while growth in weight was highest (102.7g) in 2-3 years. The Maximum length at age attained Lmax was
43.8cm weighing 340.2g. The length attained at infinity (L ∞) was 41.2cm. Growth exponent (b) was 2.86.
Length performance index (θ1) value was 2.63. Weight performance index value (Ø) was 2.84. Growth
coefficient (K) value was 0.38. The hypothetical age at which length is zero (To) was –0.35; and the maximum
age estimated was 5 years. There was no temporal variation in the condition of the fish through out the year
with condition index value ranging from 0.83 – 1.00 and condition factor value of 0.94. Total mortality (Z)
value was 1.5yr-1. Natural Mortality (M) value was 1.28; fishing mortality (F) value was 0.22. Value for the
rate of exploitation w as 0.30 with corresponding percentage value of 75. Hemisynodontis membranaceus
populations from the fresh water reaches of the lower nun river was higher than the optimal value for
sustainable yield, for the exploitation of the fishery; therefore stands the risk of over exploitation if urgent
measures are not taken to effectively manage the fishery.
Key words: Hemisynodontis membranaceus, age and growth, mortality, condition factor, Nun River, Nigeria,
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Cite this Reference:
J.F.N. Abowei, . Aspects of Hemisynodontis membranaceus (Greffroy-st Hilare, 1809) Population Dynamics from the Fresh Water Reaches of Lower Nun River, Niger Delta, Nigeria. Advance Journal of Food Science and Technology, (1): Page No: 27-34.
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ISSN (Online): 2042-4876
ISSN (Print): 2042-4868 |
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