This study attempts to ascertain the identity of Schilbe intermedius (Family: Schilbeidae) in Jebba Lake using quantitative (mophometric and meristic) and qualitative (colour and shape) parameters that makes identification easier. One hundred (100) specimens were collected and used for the study. There was relationship between body weight and length of fish (a=0.039, b=2.332, r=5.96). The parameters are similar to description of other authors. There is also absence of adipose fin found in the species, which is due to the geographical location

Bankole, N.O.

Bwala, R.L.

Kwen, K.

Umar, R.

Usman, B.I.

Yem, I.Y.

Aquatic Commons

Introduction
Rationale and scientific management of fish according to Ribbink (1991) depends on the fundamental understanding offish biology and ecology. Taxonomic studies have been going on right from the inception of the century because of itsgreat contribution to management of fishery resources be it in freshwater, brackishwater or marine. Fish identification
from any geographical region be it lake, river, floodplain etc is the first step for its proper utilization. Cailliet et al. (1986)
reported that a good character is any attribute of an organism that can be detected and used to describe that particular organ-
ism. Over 10,000 fish species according to Lundberg et al. (2000) live in freshwater, which makes up about 40% of global
fish diversity.
Stianssny (2002) reported taxa of some well-studied fish species. However, to date no comprehensive global analysis
from freshwater when compared to those from the terrestrial system (Myers et al., 2000; Olson et aI., 2001). Some of this fish
species are either not been identified at all, not been properly identified or their names have changed. Omoniyi (1997) have
worked on morphometric parameters of Tilapia zillii, Njoku and Keke (2002) on that of Citharinus latus and Paugy et al.
(2003) on Hydrocynus spp. and Tilapia spp. amongst others. Roberts (2003) reported that numerous fish stocks and species
have declined both in abundance and composition. While some have gone extinct, others are threatened and at the verge of
disappearing.
The lake harbours the family Schilbeidae that is common and abundant, which play an important role in the commer-
cial fishery of the lake.
This study, therefore, attempts for the first time to ascertain the identity of Schilbe intermedius (formerly Schilbe
mystus) in the lake through analysis of morphometric and meristic features and other peculiar characteristics that makes field
identification easy.
Materials and Method
• Study area. Jebba Lake was created after the damming of RiverNiger in 1983about 100km below Kainji at Jebba
for electricity generation. It is situated between latitudes 9°35' Nand 9°50oN and longitudes 4°30' E and 5°00' E.
The lake is about 100km long and about 12km at its widest point. The maximum depth is 105m while the mean
Abstract
This study attempts to ascertain the identity of Schilbe intermedius (Family: Schilbeidae) in Jebba Lake using quantitative (morpho-
metric and meristic) and qualitative (colour and shape) parameters that makes identification easier. 100 specimens were collected and
usedfor the study. Therewas relationship between body weight and length offish (a=0.039, b=2.332, r=5.96). Theparameters recorded
are similar to description of other authors. There is also absence of adiposefin found in the species, which is due to the influence of
geographical location.
Keywords: Morphometric, meristic butterfish, Jebba Lake.
Kwen, K. / Usman, B. 1/ Umar,R.
Yem,1. Y./ Bwala, R. L. / Bankole, N. O. /
The identity of Schilbe intermedius in Jebba Lake,Nigeria
257
2.9-3 8
5.0-13.6
1.3-19,2
Morphometric
I. Percentage of standard length
Booy_,_depth
Caudal peduncle length
Length of pectoral fin
RangeParameters Mean ± SO
Table 3: Percentage morphometric and meristic measurements of S. intermedius in Jebba Lake,
Parameters Range Mean ± SO
Body depth 1.4 - 2.6 3.24 ± 0.33
Caudal peduncle depth 1.0 - 1.3 1.11±0.10
Caudal peduncle length 0.7 -1.6 1.29 ± 0.19
Length of dorsal base 0.6 -1.0 0.82 ± 0.10
Length of anal base 5.0 - 7.8 5.64 ± 0.60
Length of pectoral fin 1.0 - 2,3 1.64 ± 0.28
Length of pelvic fin 0.9 -1.7 1.26 ± 0.20
Gape width 0.9 - 1,9 1.13 ± 0.21
Jaw length 0.4 - 0.6 0.51 ± 0.07
Head width 0.9- 2.0 1.16±0.23
Snout length 0.4 - 1.1 0.62 ± 0.12
Length of longest dorsal spine 1,2 - 2.4 1.77 ± 0.25
Head length 1.7 - 2.8 2.20 ± 0.21
Table 2: Morphometric measurements of S. intermedius in Jebba Lake.
Mean:t SO
11.92 ± 0.78
15.30 ± 0.96
22.89 ± 4.90
Maximum
14.00
17.00
30.00
Minimum
11.00
14.00
10.00
Parameters
Standard Length (em)
Total Length (em)
Weight (g)
Table 1: Body measurements of S. intermedius in Jebba Lake.
n =100
Results and Discussion
Validationof the specimen was done by comparing the values of body proportions and meristic counts obtained with
standard keys:De Vos(1995) and Paugy et al. (2003). Descriptive statistics and linear regression were used to calculate range,
means, standard deviations and coefficient of regression.
......
• Body measurements. Morphometric characters were measured (to the nearest centimeters), taken from the left ~
side of each specimen using dial calipers (Mitutoyo Corporation), meter rule, measuring board and weigh balance. ~
Meristic characters were also evaluated according to Gunther (1966), which includes fin ray counts on dorsal, anal r;;
and pectoral, number of gill rakers on the lower region of the gills. Qualitative characters, which include the shape (/l
txland colour of each specimen, were also considered for the validation. ......
oe-oo
~
depth is about 11meters. The lake gets the major bulk of its water supply from the discharge of Lake Kainji while
tributaries like Rivers Eku,Awun and others also discharge into the lake (Ita et al., 1983).
• Sample collection. 100 specimens were collected from gill nets catches of artisanal fishermen for 3 months.
Specimen were identified tentatively and transported in ice-chest box to the laboratory for analysis. Care was taken
V1
not to damage the fins and other appendages. Specimens were preserved in 5% formalin after analysis for future
reference.
PROCEEDINGS OF 28TH FISON ANNUAL CONFERENCE, NOV. 25-30, 2013
Table I shows the body measurements of S. intermedius used for the study. Standard and total lengths range between
11.00em-14.00em with mean 11.92±0.78 and 14.00cm-17.00em with mean 15.3±0.96 respectively, while the weights range
from 10.00g-30.00g with mean 22.89±4.90. There was no significant difference (p>0.05) in the lengths and weight of the spe-
cies. Linear regression shows that there is relationship between body weight and length offish (a=0.038, b=2.3315, 1=5.955).
Table 2 shows morphometric parameters measured. These include body depth, caudal peduncle length, gape width, length
of dorsal base, jaw length, length of anal base, snout length, and head width amongst other. These parameter values did not
show any significant difference. Researchers such as Gunther (1966) and Leveque et at. (1990) did report morphometric pa-
rameters could be used to establish the identity offish species.
Body proportions measured (Table 3) shows body depth (2.90-31.80%), caudal peduncle depth (5.00-13.60%), head
length (14.20-21.70%), and length of pectora I fin (1.30-19.20%) as percentage of standard length. In the case of percentage
head length as it relates to other parameters, head width is (40.00-71.40%), snout length (18.20-39.30%), length of pelvic fin
(45.00-77.30%); percentage body depth to caudal peduncle Icngth (31.40-53.80%) and percentage caudal peduncle length
(50-108%) to caudal peduncle depth.
Meristic attributes (Table 3) shows that the dorsal region has, single spine, 1-2 soft fins and 4-6 soft rays. Similarly,
Paugy et al. (2003) did report pectoral rays between 5-8 with a single spine. Idodo-Umeh (2003) reported Schilbe intermedius
having 41-66 branched rays on anal fin, dorsal fin with spine and 5 branched rays, absence of adipose fin, causal fin forked
and bends downward. Paugy et al. (2003) reported 41-66 anal fins, whereas 63-66 was reported in this study, which is within
the range. De Vos (1995) did report that the number of anal fins varies witb geographical origin of specimen. The lower part
of the first branchial arc has 8-13 gill rakers (Table 3). Similar observation was also reported by ldodo-Umeh (2003).
The body eolouration shows that the head, dorsal region and sides are blackish, which tends to become silvery or whit-
ish down to the belly. There is also a prominent dark spot just after the operculum on both sides of the fish, absence of adipose
fin or tissue, the snout is not prominent as in the case of Schilbe mystus and the caudal fin bends downward. The head and
back according to Paugy et at. (2003) are dark brown with two brownish or blackish bands on the sides, one along the lateral
line and another above anal fin base. As the species grows the color pattern fades: the head and back remains brownish while
the bands on the lateral line fades and the sides become more or less whitish or silvery. Idodo-Umeh (2003) reported the spe-
cies having grayish-brown back, sides and belly silvery white and a large spot below the operculum.
Conclusion
The results show that most of the morphometric attributes of S. intermedius is similar to previous description of other authors
except for geographical influence on some attributes (adipose fin or its rudimentary) which makes it peculiar.
Parameters Range Mean ± SO
Length of pelvic fin B.2 -15.5 10.54±1.67
Length of longest dorsal spine 10.4-20.9 14.B4±2.05
Head length 14.2-21.7 1B.46±146
V1 II. Percentage of head length
'T1 Head width 40.0-71.4 52.54±7.56...... Snout length 1B.2-39.3 2B.45±4.51(/)
::r: Length of dorsal base 2B.6-52.9 37.60±5.44
tT1 Length of pectoral fin 73.26±10.62:;d...... Length of pelvic fintT1
(/) III. Percentage body depth 47.6-100
t;d
Caudal peduncle length 45.0-77.30 57.32± B.34......0
t-< IV. Percentage caudal peduncle length 31.4-53.B 40.B2±5.B40
4) Caudal peduncle depth 50-10B BO.04±12.41
><
Meristic
Dorsal soft fin 1-2
Dorsal soft rays 4-6
Anal soft rays 63-66
Pectoral rays 5-B
Total pectoral spine 1
Lower gill rakers B-13
Color Head, dorsal region and sides blackish,
silvery or whitish down the belly
PROCEEDINGS OF 28TH ANNUAL CONFERENCE, NOV. 25-30, 2013
259
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The identity of Schilbe intermedius in Jebba Lake, Nigeria

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The identity of Schilbe intermedius in Jebba Lake, Nigeria

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