International Journal of Aquaculture, 2015, Vol.5, No.31 1
-
7
2
During each collection, samples were ice check and
moved to the College of Agriculture Lafia, in the
Fisheries Department Laboratory for analysis. Total
length (cm) and other morphometric measurement
were taken using meter rule while weight (g) was
gotten using the sensitive weighing balance.
Biometrical parameters recorded includes six
morphometric measurement and seven meristic counts
as determined and described by Samaradivakara et al.
(2012). The morphometric variables standard length, weight,
body depth, pre-dorsal distance, eye diameter, caudal
fin length. The meristic counts pectoral fin ray, pelvic
fin ray, dorsal fin ray, anal fin ray, Pore lateral line
scale, Upper teeth rows, Lower teeth rows
2.3 Statistical analysis
To ensure that variations in this study were only
attributed to body shape differences, and not to the
relative sizes of the fish, size effects from the data set
were eliminated, by standardizing the morphometric
parameters using the allometric formula given by
Elliott
et al.
(1995):
M
adj
= M (Ls / Lo)
b
;
Where M = original measurement, M
adj
= size-adjusted
measurement, Lo = TL of the fish, Ls = overall mean of
the TL for all specimens.
Parameter b was estimated for each character from the
observed data as the slope of the regression of log M
on log Lo, using all fish in all groups. However, it has
been established that meristic characters are independent
of size of fish hence should not change during growth
(Strauss, 1985; Murta, 2000) therefore the raw data
were analysed without transformation as described
above. Statistical analyses in the present study
included descriptive statistics using Minitab 14 as well
as univariate analysis of variance using Genstat
®
discovery edition IV. Where significant differences
occurred, Duncan’s least significant difference was
used to separate the mean values of morphometric
and meristic parameters. Morphometric and meristic
data were subjected to discriminant function
analysis (DFA) using Genstat
®
discovery edition IV.
3 Results
Table 1
compares the morphometric measurements of
the four fish species in the study. Result reveals that
A.
dentex
had significantly higher standard length (20.88)
than
H. breves
and
H
.
foskali
(19.11and 18.84 respectively)
however least value was recorded in
B. leuciscus
.
Similarly Mean weight of
A. dentex
was higher (119.40)
compared to
H
.
foskali
(96.93),
H. breves
(94.60) and
B. leuciscus
(14.24). Similarly Predorsal distance was
higher in
A. dentex
(9.08), followed by
H
.
foskali
and
H. breves
(8.09 and 6.54 respectively), with the lowest
value recorded in
B. leuciscus
(2.57). Mean eye
diameter of
H
.
foskali
was higher (8.74) than other
species while
B. leuciscus
recorded the lowest (0.41).
Mean pectoral fin ray in
H
.
foskali
and
A. dentex
was
12 in number and higher than the number observed for
B. leuciscus
and
H. breves
(11 and 9 respectively),
similarly, pelvic fin ray was highest in
H
.
foskali
(13)
and lowest in
A. dentex
and
B. leuciscus
(9)
.
Mean
dorsal fin ray of
A. dentex
and
H. breves
was 10 in
number and higher than 8numbers recorded in
B.
leuciscus
and
H
.
foskali.
Anal fin ray was higher in
H.
breves
(22) and lowest in
H
.
foskali
(9). Result also
reveal caudal fin ray to be much in
H. breves
(23) and
least in
H
.
foskali
(12). Pore lateral line scales
however, were higher in
H. foskali
(6) and lower in
A.
dentex
(3), there was no difference in the lower teeth
rows of the fish species however 3 row of upper jaw
was observed in
H. breves
as against 2 rows observed
for the other species.
Relationships of the morphometric measurement and
meristic count analysis among the selected f ish
species from doma dam was considered according to
the 1st and 2nd discriminant function (DF) (Figures 1
for morphometric parameters and Figure 2 for meristic
count). The 1
st
DF accounted for 76% and the 2
nd
DF
accounted for 12% of among-group variability of the
morphometric data, and together they explained 88%
of total among-group variability. On the other hand,
the 1
st
and 2
nd
DF of the meristic count analysis
accounted for 75% and 16% respectively of the
among-group variability; together they explained 91%
of total among-group variability. According to the
canonical discriminant function coefficients obtained
for the morphometric data, the most influential
morphometric variables using the 1st DF were the
predorsal distance, body depth, standard length and
eye diameter, while anal fin ray, caudal fin ray and
pelvic fin ray constituted the most influential meristic
variable for discrimination of the groups. Plots of
canonical discriminant functions 1 of the morphometric
measurements (Fig. 1) clearly showed a complete overlap
between
H. breves
and
H. foskali
and a partial overlap
with
A. dentex
and separate however from
B. leuciscus
.
