The effects of some environmental factors on the fecundity of Tilapia species (Family Cichilidae) was carried out at the Kigera dam. Four Tilapia species caught were Tilapia zilli, Hemichromis fasciatus, Sarotherodon galilaeus and Oreochromis niloticus while the environmental factors considered were water temperature, Dissolved Oxygen, pH value, level of rainfall and rate of sunshine and range of time. 43 fish comprising of 25 male with (58.1%) and 18 females having (41.9%) were studied with 74.42% been sexually matured. Both high levels of rainfall and dissolved oxygen favoured fecundity. The spawning peak occurred in (July), environmental factors monitored indicated that dissolved oxygen ranges from 3.7 to 4.45mg/lit rainfall ranges from (34.90mm to 237.80mm) sunshine ranges from (5hrs-8hrs) and pH ranges from (7.35-7.45). The spawning of these species in their natural or hatchery condition is therefore best achieved during the peak of raining seaso

Issa, E.A.

Olufeagba, S.O.

Raji, A.

English

Aquatic Commons

EFFECTS OF SOME ENVIRONMENTAL FACTORS ON THE FECUNDITY OF TILAPIA
SPECIES (FAMILY CICHLIDAE) IN KIGERA RESERVOIR NEW BUSSA
*Eleshin-nla Abdulfatati lssa
"Olufeagba S. O.
ad
eaminu
*Federal College of Freshwater Fisheries Technology, Baga. Borno State.
**National Institution for Freshwater Fisheries Research, New Bussa.
ABSTRACT
The effects of some environmental factors On the fecundity of Tilapia Species (Family cichifidae)
was carried out at the Kigera dam. Four Tilapia species caught were Tilapia Zilli Hemichromis
fasciatus Sarotherodon galilaeus and Oreochrotnis niloticus while the environmental factors
considered were water temperature, Dissolved Oxygen, PH value, level of rainfall and rate of
sunshine and range of time. 43 Fish comprising of 25 male with (58.1%) and 18 females having
(41.9%) were studied with 74 42% been sexually matured. Both high leve/ of rainfall and
dissolved Oxygen favoured fecundity. The spawning peak occurred in (July), Environmental
factors monitored indicated that dissolved Oxygen ranges from 3.7 to 4.45mg Pit rainfall ranges
from (34.90mm to 237.80mm) sunshine ranges from (5hrs Mrs.) and PH ranges from (7.35
7,45). The spawning of these species in their natural or hatchery condition is themfore best
achieved during the peak of rainning season.
INTRODUCTION
The ability to produce new living individuals is a characteristic feature of all living
organism and is known as reproduction. Reproduction is the only means by which life is
maintained (Sarojini et al. 1979). Jalabert et al (1982), observed that the reproductive behaviour
of Tilapia have paradoxical consequences; on one hand, this aptitude which allows easy and
rapid propagation in various tropical and subtropical environments, partially explain the economic
interest in these species for culture. Another aspet of the reproductive efficiency of Tilapia is
precocious sexual maturation which can occur as early as 3 mouth (McBay, 1961) and depends
probably, in addition to genetic factors on environmental factors like temperature (Hyder 1970),
food availability, socio-factor e.t.c.
Reproductive behaviour could be affected by the environmental factors such as
Temperature Dissolved Oxygen, Rainfall, Photo period.1Ìa1igsto Lagler et al (1962), both
the development period and the hatching period are generally shorter at higher temperature than
at lower temperature interestingly, many species normally develop in nature under the
temperature condition which area not optimum as determined by laboratory experiments, species
differ in their temperature tolerance during developments but generally, there are temperature
wnicn are too low and too high for physiological processes (Lagler et al 1962).
861
As soon as sexual maturation is attained and temperature is suitable, most female
cichlids spawn between 4 to 6 weeks interval. This usually result in continuous production of fry
throughout the year.
In order to breed, Tilapia, the water temperature should be at least 20°c (Huet, 1970:
Balarin and Hatton, 1979), but certain species are able to reproduce Tilapia sparrmanii at 16°c
(climits 1957) other factors soon to play a releasing role, notably photoperiodicity and light
intensity (Balarin and Hatton (1979), as well as the season, via water temperature (temperature.
linked with grounds) or other mechanism.
In certain tropical and subtropical region low temperature inhibit reproduction; the length
of the time depending on the latitude and altitude of the place the duration of the breeding
season, the duration of spawning in a year and consequently overall fecundity.
In the. study of fish fecundity, different author have defined fecundity in various ways.
Lowe (1955) defined fecundity in tropical fishes as the number of eggs produced during the life
time of an individual. Nikolsky (1963) and Lowe Mc Connell (1956) defined fecundity as the
number of Ova ripdning at one time in an ovary. The term absolute fecundity has been used by
Bagenal (1968) and Fryer, (1961), as the number of eggs ripening in the female prior to
spawning. Therefore in this work fecundity is taken as the ripe Ovaries of an individual matured
female fish,
l'iloectives of this study
The objective of this study are:
To study the spawning peak and its relationship with the environmental factors.
Study the fltictuation in the sexualmaturity of the family cichlidac in Kigera Reservoir
Study sex composition, variation in length and weight.
iVIATERIALS AND METHODS
FishigkAnd Material Description:
Fishing was done using gill nets on Thursdays from May to July, various sizes of gill net
were used 2", 2.5" and 3" stretched Mesh size, which were set between 5 6 p m and retrieved
between 7 8 a.m the following morning.
Fish Analysis
Fish collected were taken to the laboratory where all specimens were individually
measured using metric ruler calibrated in centimeter and weighed using Harvard trip weighing
balances. The standard length was measured from the snout tip to the vertebral column trip, while
the total length was measured from the snout tip to the end of caudal fin. Total weight of all.
samples collected were taken. and Gutted weight were taken as the weight of fish after all
visceral materials had been removed. Then the percentage of ranges of the standard length were
calculated using formula.
No of Fish in colum x 100
Total no of Fish
Sex determinatton were based on the internal and external Morphologies The genital
papilla of females have three openings namely, the anus,. transverse genital °periwig and Oviduct
wrdcn is scarcely visible to the naked eyes.
The males have openings situated just in front of the anal fin, one is the anus and the
other is the aperture sexually matured fish have pink coloration.. On dissecting the fish to reveal
862
the visceral parts the gonad were classified into maturing stages as described by Kesteven,
(1960).
The matured eggs were removed and put in a beaker and mixed with little quantity of
water, it was shakened to free the eggs from its Ovarian tissue. It was left for some hours.
Counting of eggs were done manually with the aid of Magnifying hand lens. The number of
matured eggs in each species were tabulated and mean fecundity were calculated for each
month using the formular below.
Total no of Matured r (ids
No. of Matured female Fish
Water parameter:
Temperature:- The water temperature was taken using mercury glass thermometer
graduated in degrees centigrade (°C). Both the leVel of rainfall and radiation data were collected
from NIFFR Headquarters' Meteorological station, Rainfall level measured in (mm) while the
sunshine radiation, measures with radiation chart and were graduated in hours.
The PH of the water was taken every Thursday using LOVIBOND COMPARATOR.
Dissolved Oxygen was determined using winkler's method.
Result and Discussion
A total number of 43 tilapia were collected comprising 25 males (58.1%) and 18 females
(41.9%).
Table 1 shows the total number of each species collected and their correspondence
percentages. T. zilli were 17 in number comprising of 9 males and 8 female 'representing 52.94%
and 47.06% respectively. O. niloticus were 15 comprising of 11 males representing 73.33% and 4
females representing 26.67%. S. galilaeus were 8, having 3 males and 5 females representing
37,5% and 62.5% respectively, while H. fasciatus were 3, 2 males and 1 female representing
66.67% and 33.33% respectively. Table 2 show the percentage and ranges of standard length of
each species. The percentages of fish with standard length ranging from 11 15cm was
(37.21%) while the percentage of fish with standard length ranging from 21 25cm was 9.3%.
Total number of matured female fish of each species and their fecundity are shown in
Table 3. Eight T. zilli had mean fecundity of 725, S. qalileus were 5 with mean fecundity of 939, 0
niloticus were 3, having mean fecundity of 1,412 while H. fasciatus was 1 with fecundity of 520.
Table 4 show the gonad maturation stages for each month and sex of each species from
May July 74.42% of the total number of 43 tilapia were found to be between stages 4 and 6.
The high percentage of sexual maturity shows influence and interaction of the sexual characters
with the environmental factors.during the period of the research.
Table 5 shows the number of fish that were matured and their monthly mean fecundity
while figure 1 shows the relationship between the fecundity and the time in months from May
July. It was observed in T zilli fecundity was 318 in May. 606 in June, and 1,225 in July, O.
niloticus mean fecundity was 915 in May and 1.661 in July. S. qalileus has801 in June and 1,031
in July while H. fasciatus was zero in May and 520 in June.
Table 6 shows the temperature for each month (May July) while figure 2 shows the
relationship between the means fecundity and the temperature. It was noted that more riped eggs
were obtained within the temperature range of 29 31.5°C. temperature is very important to the
reproductive behaviour of tilapia. At the water temperature of 34.5°c I. Zilli it has means fecundity
of 318 at the temperature of 31.5°c it has means fecundity of 606 and 1,225 at the temperature of
863
27°c 0 niloticus has means fecundity of 915 at the water temperature of.31:5°c and 1661 at the
temperature of 29°c.S. galileus has means fecundity of 801 at the temperature of 31.5°c and
1,031 at 29°c, while H. fasciatus has no fecundity at the temperature/of 29°c.
Table 6 shows the mean PH value for each month while figure 3 Shows the relationship
between the mean fecundity and the PH. It was observed that PH value Of 7.4javours greater
number of fecundity of 1225 in I. ZiHi, 1661 in O. niloticus and 1031 in S. galiteus while PH
value of 7.45 favours least number of mean fecundity of 318 in 1. Zilli and none in other species.
Figure 4 shows the mean fecundity, dissolved Oxygen and their relationship. It was
shown that high level of dissolved Oxygen has no negative effect on the number of fecundity.
Finally, Table 7,8 shows the mean rate of sunshine, and the level of rainfall while figure 5
and 6 shows the fecundity relation with mean radiation and level of rainfall respectively the mean
radiation was inversely proportional to the mean fecundity while the level of rainfall was directly
proportional to the mean fecundity i.e the lower the rate of sunshine the higher fecundity and the
higher the rainfall the higher the fecundity.
CONCLUSION
The result obtained after studying the effects of some environmental factors on fecundity
of Tilapia species (family cichlidae) in Kigera Reservoir proved that environment factors have
direct effects on fecundity of Tilapia species in Kigera reservoir.
The result shows that high level of rainfall and rate of dissolved Oxygen are directly
proportionally to he fecundity while the rate of sunshine and rate of water temperature are
inversely related to the fecundity. And pH value of 7. 4 was found to be more productive.
It can be deduced that high level of rainfall and dissolved Oxygen, low water temperature,
how rate sunshine and pFi of 7.4 have no negative effects on the fecundity of Tilapia species in
Kiaera reservoir during the experimental period.
. Table 1: SEX COMPOSITION OF CICHLID FISHES IN K1GERA RESERVOIR
.
ii Species I Total Male % i Female % Ratio of male to
, No of female
. fish
1
T. zilli 17 9 52.94 I 8 47.06 1.13:1
O. niloticus 15 11 73.33 i 4 26.67 1 2.75.1
S. dalileus 8 3 37.5 I 5 62.5 i 0.6:1
H. fasciatus 3 2 66 67 I
_.i. _ 33.33 1 2.1 i
Table 2: STANDARD LENGTH DISTRIBUTION OF CICHLID FISHES IN KIGERA
RESERVOIR
RangeSpecies 1 5 (cm0
T. zilli
O. niloticus
S. galileus
H. fasciatus 2 1
6 10(cm) 11 15 (cm) 16 20
5 7 5
1 3 4
1 5 5
20.93% 37.21% 32.56%
864
1ö121 25
4
9.30% j -
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25-
TABLE 7: RATE OF SUNSHINE AND LEVEL OF RAINFALL FLUCTUATION DURING
THE EXPERIMENTAL PERIOD IN KIGERA RESERVOIR
DATE OF SUNSHINE DURING HE EXPERIMENTAL PERIOD
r r1MONTH MIN. RADIAITON MAX. RADIATION I MEAN RADIATION
I MAY 1 41/2 hrs. 8% hrs. i 61/2 hrs
! JUNE i 1 hrs 81/2 hrs 1 43/4 hrs
JULY
, 1/2 hr i 5 hrs L23/4 hrs.
867
Species No. of Matured
female fish
Month Min. fecun. Maz. Fec. Mean fec.
T. zilli 1 MAY 318 318 318
5 JUNE 307 1015 606
2 JULY 1112 1338 1225
O. niloticus - MAY - - -
1 JUNE 915 915 915
2 JULY 1102 2220 1661
S. qalileus - MAY - - _
2 JUNE 700 902 801
3 JULY 895 1226 1031
H. fasciatus - MAY - - -
1 JUNE 520 520 520
- JULY - - . -
I
TABLE 6: RESULT OF WATER PARAMETERS IN KIGERA
MONTH MIN. WATER TEMP. MAX. WATER TEMP.TC MEAN WATER
PC TEMP. ()C
34-.5 --MAY 34 35
JUNE 28 35 31.5
JULY 28 30 29
MONTH MIN. DO2 MAX. DO2
-1
MEAN DO2
MAY 3. 2mg / lit 4. 2mg lit 3. 7rng / lit
JUNE 3. 0 mg / lit 5. 2mg / lit 4. 'I mg / lit
JULY 3. 8cm / lit 5. 1mglit/ 4. 45m_g_ / lit
- --
MAX PHMONTH MIN. PH MEAN
MAY 7.4 7.5 7.45
JUNE 7.3 74 7.35
JULY , 7.4 7.4 7.4
TABLE 5: FECUNDITY OF CICHLID FISHES IN KIGERA RESERVOIR
TABLE 8: LEVEL OF RAINFALL DUIRNG HE EXPERIMENTAL
868
REFERENCES
Baganal, T. B. 1968) Fecundity in method for assessement of fish production in freshwater (ed.
Ricker, W.E.) I B. P. Hand book No. 3 Block well: Oxford 160- 169.
Balarin, J,D. and J. P. Hatton (1979) "Tilapia Aguide to their Biology and culture In African.
University of stirling U -K. P. 29'.
Chimits, P. (1959); Tilapia and their cuture, a second review and Bioliography. FAO Fish Bull;, 10
(1) 1 24.
Fryer, G. (1961); Observation on the 'Biology of the cichlid fish _Tilapia.Variabilis Boxlenger in
northern waters of lake Victoria-(East Africa). Rev. Zool, Bot, Afr. 64: 1 33.
Huet, M. (1976); Text Book of Fish Culture; Brewedin and cultivation of Fish Translated by H.
Kohn. Fishing News Led. Famhani, survey, Enland. 436p.
Hyder, H (1970) Gonadal and reprodOctive pattern in Tilapia leucosticta (Teledstei; cichlidae) in
an equatorial lake, lake Naivasha (Kenya). Zool. Lond. 162.174-195
1abert, B. and Zoliar, Y (1982): Reproductive physiology in cichlid fishes. with Particular
reference to Tilapia and sarotherodon, p. 129 140
-
Kesteren, G. L. (1960) Manual of field Methods in fishes biology. FAO. Man. Fish. Sci:i 152p
Lagler, K. F., Bardach, J. E. and Miller, R. R. (1962) Icthyology Wiley and Sons; New York.
London.
Lowe, R. H. (1955) The fecundity of Tilapia species E. Afr. Agric. 45 52
Lowe Mc cone!, R. H. (1956) The breeding behavious of Tilapia species (Pikes; Cichlidae)
natural waers; obervations on I. Kanwo (Poll) and L Variabilis Boulenger,. Behaviour P.
146 163
Mc Bay, L. G. (1961) The Biology of TilapiaTilapia nilotica (Linueus proc. 15th Ann." Conf. S. E.
Assoc. Game and fish. Commissioners, Oct. 22 25: 208 218.
Nikolsky, G. V. (1963) The ecology of fhshes. Academic press London and New York 352 p.
Sarolini, T. R. Sheila, P. and Charles, T. P. (1979); Modern Biology for Secodary Schools.
MONTH TOTAL RAINFALL PER MONTH
MAY
JUNE
JULY
34. 90mm
120. Omm
237. 80mm


Effects of some environmental factors on the fecundity of Tilapia species (Family Cichlidae) in Kigera Reservoir, New Bussa

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