International Journal of Marine Science, 2016, Vol.6, No.24, 1-8
3
Fish species such as
Ethmalosa, Gobioides, Cynoglossus.
and
Pomadasys
,
Pseudotolithus, Tilapia, Mugil, Liza,
Clarias, Selene, Macrobranchum,
Callinectes Tillapia guinensis, Gymnarchus niloticus, Chrysichthys
nigrodigitatus, Bathygobius soporator, Pomadasys peroteti, Marcusenius psittacus
are common in Badagry creek.
Reviews on fishes and fisheries of Badagry creek include that of Solarin and Kusemiju (1991), Lawal-Are and
Kusemiju (2000), Chukwu and Kuton (2001), Lawal-Are (2001), Ajado and Edokpayi (2003), Kumolu-Johnson
(2004), Akintola (2007), Soyinka
et al.
(2010). The surrounding vegetation is composed mainly herbs and shrub
plants dotted by raffia palm (
Raphia sudanica
), oil palm (
Elaeis guineensis
) and coconut palms (
Cocus nucifera
).
Floating plants such as the water lettuce (
Pistia stratoites
), duckweed (
Lemna
sp.) and water hyacinth (
Eichhornia
sp.) often cover some parts of the water surface (Akin-oriola
et al.
2004).
Materials and Methods
Sample Collection
: Fin-fishes used in this study were purchased weekly from fishermen at Badagry creek between
November 2014 - June 2015 (8 months). A total of 1008 fin fish specimens were examined. They were caught
principally with cast net and surrounding net, with 76mm mesh size. The fish were transported to the laboratory of
Department of Fisheries, Lagos State University for analysis.
Sex Ratio Determination
: The sex of each specimen was determined by visual examination of the genital openings
using the naked eye and magnifying lens. The ratio of male to female specimen were determined and tested
statistically by chi – square method.
The chi-square was expressed mathematically as
Chi
2
= (O – E)
2
/ E
.
Where: O is the Observed sexes and E is
the Expected sexes.
Lenght – Weight Relationship:
Body weight was measured to the nearest 0.1 g using a sensitive electric digital
scale, while Lengths were measured to the nearest 0.1cm using a meter rule in the laboratory as described by
Olatunde (1978). The length-weight relationship was estimated using the equation:
W = aLb
Where: W=Weight
of the fish in grammes, TL=Total lenght of the fish in centimeters.
a=Regression constant. b=Regression co-efficient. The parameters a (intercept) and b (slope) were estimated by
linear regression based on logarithms:
Log (W) = Log (a) + b Log (L).
Where: W = weight (g) of the crabs, L =
Total lenght of the fish in centimeters.
Condition Factor: The fulton’s condition factor for the fish specimen were calculated using the formula:
K =
100 ( W / L
3
)
.
Where: K=Fulton’s condition factor, L=Total lenght of the fish in centimeters, W= Weight of fish
in grammes
Results
A total of 1008 specimens were examined. The total length ranged from 12.85±1.54cm – 27.49±4.75cm, and the
body weight ranged from 38.50±14.04g – 159.09±28.24g
Oreochromis niloticus
having the least and
Marcusenius
senegalensis
having the highest. Table 1 shows the summary of results of the biology (e.g. Growth pattern) of all
the species studied, with the mean condition (K) factor for the fish species ranging from 0.77 – 5.37,
Marcusenius
senegalensis
having the least and
Pomadasys peroteti
having the highest. 75% of fish species sampled had K –
factor greater than or equal to 1.
The value of the regression (b) showed that the pattern of growth was positive allometry (b > 3), except for only
two (2) species within the population i.e.
M. senegalensis (b =2.12)
and
G
.
niloticus (b =1.39)
which shows that
these two (2) species were not growing appropriately in relation to the body length (cm). However, most of the
species have b values higher than 3, especially for
Sarotherodon melanotheron
with b value equals to 15.59. The
co-efficient of regression r, ranged from 0.06 – 0.91,
Tilapia mariae
having the least. Positive values obtained for
the correlation coefficient (r) shows that there is an increase in the body weight with increase in lengths. The
length weight relationships of all the species are presented in Figures 2 – 13.
