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International Journal of Aquaculture 2012, Vol.2, No.10, 65
-
71
http://ija.sophiapublisher.com
65
Research Report Open Access
Study on the Adaptability Status and Reproductive Success of
Oreochromis
niloticus
L. (Pisces: Cichlidae) and Carp (
Cyprinus carpio
L., 1758) in a
Tropic Reservoir (Fincha, Ethiopia)
Fasil Degefu , Gashaw Tesfaye , Fikadu Tefera
National Fisheries and Other Living Aquatic Resources Research Center, Sebeta-Ethiopia, P.O.Box 64, Sebeta, Ethiopia
Corresponding author email: fasildeg2000@yahoo.com;
Authors
International Journal of Aquaculture, 2012, Vol.2, No.10 doi: 10.5376/ija.2012.02.0010
Received: 31 Oct., 2012
Accepted: 06 Nov., 2012
Published: 28 Nov., 2012
Copyright: © 2012 Degefu. This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Degefu, 2012, Study on the Adaptability Status and Reproductive Success of
Oreochromis niloticus
L. (Pisces: Cichlidae) and Carp (
Cyprinus carpio
L., 1758)
in a Tropic Reservoir (Fincha, Ethiopia), International Journal of Aquaculture, Vol.2, No.10 65-71 (doi: 10.5376/ija. 2012.02.0010)
Abstract
The adaptability status and reproductive success of the introduced fish Nile Tilapia (
Oreochromis niloticus
L.) and
common carp (
Cyprinus carpio
L., 1758) in Fincha reservoir, Ethiopia were studied on monthly basis from July 2006 to August 2007.
Gill nets of different mesh size (60 mm, 80 mm, 100 mm, 120 mm and 140 mm, stretched mesh size) and beich sein (50 m long)
were used to harvest the fish (a total of 645 fishes). Total length (L) and body weight (W) of both species were measured to the
nearest 0.1 cm and 1g respectively. The results of the study showed that both fish species are adapted and have established successful
breeding population in the reservoir. The size at first sexual maturity (L
50
) for
Oreochromis niloticus
in Fincha reservoir was 21.8 cm
for female and 24.5 cm for the male while L
50
was 37.5cm and 24.5cm for female and male
Cyprinus carpio
respectively. It was
found that
Oreochromis niloticus
breeds throughout the year showing a peak breeding season in January and July in Fincha reservoir
while
Cyprinus carpio
showed a peak breeding season between March and June. The length-weight relationships, total length (L) in
cm; total weight (W) in g were calculated for
O. niloticus
(W=0.
8
×10
-2
L
3.20
; n=87; r
2
= 0.96) and
C. carpio
(W=1.4×10
-2
L
2.97
; n=558;
r
2
=0.99) and showed a curvilinear relationship signifying the fish grow nearly isometrically. A significant seasonal variation
(ANOVA, P < 0.05) was observed in the condition (K) of the fish coupled with the peak breeding season in Fincha reservoir. The
relatively low values in the condition of the fish during January, March and July seems to coincide with the peak breeding season of
the fish, which probably drains high energy for spawning. However, no significant difference was observed between sexes (ANOVA,
P>0.05). Apparently, length frequency distribution of both species indicated that the fish population is normal fish population with no
apparent problems of over exploitation.
Keywords
Breeding-season;
Cyprinus carpio
; Fincha;
Oreochromis niloticus
; Reservoir; Ethiopia
Abbreviations
ANOVA: Analysis of covariance; NFLARC: National
Fisheries and Aquaculture Research Center; L
50
: The
size at first sexual maturity; TW: Total weight of the
fish; TL: Total length of the fish
1 Introduction
Due to their economic importance tilapia are among
the most studied group of fish in African waters
(Low-McConnel, 1982). In Ethiopia Nile tilapia,
Oreochromis niloticus
is commercially the most
important and widely preferred and consumed fish. It
is one of the most important fish species in the
ecology and fisheries of almost all-Ethiopian inland
waters (Tedla, 1973; Pauly and Gaynilo, 1997).
Several investigators have studied the breeding season
and maturity size of
O. niloticus
in some lakes in
Ethiopia. For example,
Oreochromis niloticus
breed
through out the year, but its breeding activity is
intensive during the periods from January to April and
July to September in Lake Awassa (Admasu 1990;
1994 and 1996) from December to March in Lake
Ziway (Tadesse, 1988). However in Lake Tana, unlike
the Rift Valley lakes,
Oreochromis niloticus
seems to
have longer breeding season which lasts from March
to August (Tadesse, 1997).
The main breeding activity of fish species in tropical
waters has been associated with factors such as light
intensity, temperature, rainfall and water level or seasonal