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International Journal of Aquaculture 2012, Vol.2, No.10, 65
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71
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69
males) is comparable to
C. carassius
fish
in Lake
Ziway, 30.50 cm for females and 26.80 cm for males
(Dadebo and Tugie, 2009). Size at first maturity is
inversely correlated to the degree of fishing mortality.
Several investigators have noted that L
50
was related
with the condition of the fish; and the fish individuals
that are in poor condition tend to breed at smaller sizes
than those in good condition (Wootton, 1998; Teferi
and Admasu, 2002).
4 Conclusions and Recommendations
In summary,
O. niloticus
and
C. carpio
showed
isometric growth in Fincha reservoir, however, the
body condition of the fish was found to be different
between months but not between the sexes. Both fish
species in Fincha Reservoir followed the general
pattern of breeding activities in tropical water bodies
where comparatively higher proportions of fish were
in breeding condition during the onset of the rainy
season. In Fincha reservoir female
O. niloticus
matured at smaller size than males whilst male
Cyprinus carpio
matured at smaller size than females.
Therefore, capture size of the stock should be
determined taking into account the L
50
of females,
which may otherwise remove the spawning fish
during their peak breeding season. Generally the
length frequency distribution of both species in Fincha
reservoir indicated that the fish population is normal
fish population with no apparent problems of over
exploitation. However, we recommend the fishermen
have to use a fishing gear greater than 8 cm stretched
mesh size for sustainable utilization of the stock in
Fincha reservoir. Thus, the gill net being used at the
reservoir may not remove the juveniles before
replacing the next generation to sustain the yield.
5 Material and Methods
5.1 Study area
Fincha Reservoir (09
o
54`N, 37
o
27`E) is located in
west-central Ethiopia some 150 km from the capital
Addis Ababa, at an altitude of 2 200 m a.s.l.
(Figure.6).
Figure 6 Map of Ethiopia showing the location of Fincha reservoir together with its swampy area (Mesfin et al., 1988).