1

CATCH COMPOSITION OF FIN FISH IN LOWER OGUN

RIVER, AKOMOJE, ABEOKUTA, OGUN STATE, NIGERIA

BY

OLANUSI ADEOLU RICHARD

MATRIC NO 06/0820

A RESEARCH PROJECT SUBMITTED TO THE DEPARTMENT OF

AQUACULTURE AND FISHERIES MANAGEMENT, COLLEGE OF

ENVIRONMENTAL RESOURCES MANAGEMENT, UNIVERSITY

OF AGRICULTURE, ABEOKUTA.

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE

AWARD OF BACHELOR OF AQUACULTURE AND FISHERIES

MANAGEMENT OF THE UNIVERSITY OF AGRICULTURE,

ABEOKUTA, OGUN STATE, NIGERIA

JUNE, 2011

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CERTIFICATION

This is to certify that this project was carried out by OLANUSI A. R. of matriculation number

06/0820 of the department of aquaculture and fisheries management, college of environmental

resources management, university of agriculture, Abeokuta, Nigeria.

Supervisor Signature .………………………….

Dr F. I. Adeosun Date …………………………

Head of Department Signature …………………………..

Prof. Y. Akegbejo - Samsons Date ………………………….

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DEDICATION

I dedicate this project to Almighty God and to my late dad, Mr. J. A. OLANUSI who started the

upbringing and laid a solid foundation on my education.

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ACKNOWLEDGMENT

My profound gratitude goes to the Almighty God, who gave me the strength, patience,

perseverance and will to pull through this work. I am indebted to my mum, Mrs. J. A. Olanusi

for her advice, love, care, spiritual, financial and moral supports during the period. I also

appreciate my siblings; Bro Wale, Bro Niyi and Bro Tunji. Special thanks to my Uncle Elder J.

A. Olanusi and to my Aunty Deaconess Odunjo for their support during my stay in school.

My appreciation goes to my supervisor, Dr. F. I. Adeosun who stood by me during this project. I

also appreciate the support of the fisherfolks and the fish sellers at the project site for their

patience during the search for information.

My sincere appreciation goes to my project mates, Sesan, Jeffery, and Sanya for being there

throughout the project. My special appreciation goes to my fiancée, Bukola for her love, advice

and emotional support. I also want to appreciate Junior Chamber International, UNAAB Chapter

for their support and the encouragement of the Alumni. This appreciation goes to Bamgbose

Martins, Japhet Omojuwa, Bolaji Sunmola, Toba Adeyeye, Murphy, optimistic, Wale Salami,

Adewale Oluwole, Seye and the immediate past president, Tomiwa. My appreciation goes to my

entire class mates; Nicholas, Bisi, Sheu, Tope, Ehis, Kemi, Albert, Nora, ELS, Omoh, Victor,

Funke, Bright, Grace, Oliseh, Deborah, P. Dot, Ayo, Seun Opeodu, Gbemi, Tayo, Seun Folarin,

Malo, Oriyomi, Quadri Square and the rest of my class mates.

My special appreciation also goes to Winners Chapel Obantoko and Sanctuary Unit for their

spiritual support during this project. I also appreciate Christian World Outreach International for

being there as well and finally to National Association of Fisheries Students for being there as

well.

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ABSRACT

The fin fish composition in the fresh water reaches of lower Ogun River was investigated. The

project was carried out for five Month, between January and May 2011. The fin fishes comprised

a total of 41 species from 11 families. Mormyrus rume was highest in biomass (62kg) accounting

for 8.26% of the catch, while Brycinus macrolepidotus was most numerous (144) accounting for

17.5%. Bagrus bayad, Sarotherodon melanotheron, Nannocharax ansorgii and Synodontis sorex

were the least in bimass (0.2kg) accounting for 0.12%. while Bagrus bayad, Parachanna

obscura, Sarotherodon melanotheron, Garra waterloti, Barbus occidentalis, Barbus callipterus,

Nannocharax ansorgii, Mormyrus macrophthalmus and mormyrus hasselquistii were the least in

number. The major aim was to assess the fish resources of the river and evaluate the water

parameters as related to fish production. No significant difference was observed in dissolved

oxygen, nitrate, phosphate, water temperature, conductivity, alkalinity, total dissolved solid and

PH range value in the stations. The water quality parameters were favourable for fish production.

Water level and temperature were observed to guarantee high fish yield in the River. Detailed

study on species composition of this water body should be encouraged in the sustainable

utilization of its resources.

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TABLE OF CONTENT

Title page i

Certification ii

Dedication iii

Acknowledgement iv

Abstract v

Table of Content vi

List of Tables viii

List of Figures ix

CHAPTER ONE

1.1 Introduction 1

1.2 Catch composition in water body 3

1.3 Objectives 3

CHAPTER TWO

2.1 Literature review 5

2.2 Problem associated with low catch composition 10

CHAPTER THREE

3.0 Materials and method 12

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3.1 Study Area 12

3.2 Fish Sampling 12

3.3 Physico – chemical parameter 13

CHAPTER FOUR

4.0 Results 17

CHAPTER FIVE

5.0 Discussion 28

References 30

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LIST OF TABLES

Table 1 – physical and chemical characteristics of fresh water reaches of lower Ogun River,

Akomoje.

Table 2 – Fish species caught and their percentage composition of fresh water reaches of lower

Ogun River, Akomoje.

Table 3 – Weekly biomass and number of fish caught in lower Ogun River.

Table 4 – Weekly catch (kg), fishery effort and catch per unit effort for fish caught in the lower

Ogun River.

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LIST OF FIGURES

Figure 1 – An open water body of the project site.

Figure 2 – Depth controlling guage.

Figure 3 – A map showing Ogun River.

Figure 4 – Bar chart representation of catch statistics in kilogram.

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CHAPTER ONE

1.1 INTRODUCTION

Fishery resources are the major sources of dietary protein in Nigeria and the world at large. This

is why fishermen and women are been encouraged to carry out their fishing activities in all the

rivers in Nigeria. The major supply of fin fish in Ogun state comes from Ogun river for the

proper distribution of food and fishery materials.

The lower Ogun river as it were is a storage device for fishery resources. It acts as a breeding

ground and habitat for several species of fin fish. The species are dispersed evenly in the river.

Catch per unit effort of the fin fish in the river can be determined by the fishery worth in the

river. The number of fish caught is the test of a fishery worth (Cowx, 1971).

Catch statistics are important in fisheries management; it becomes imperative to update some of

the existing sampling systems.

Fin fish is mainly eaten for its protein contents; the human body utilizes proteins from fish better

than proteins from beef, pork, chicken and milk. All the proteins from fish are adequate,

important and digestible. Fin fish is also valued as a source of omega-3 (n-3) fatty acids, very

long chain polyunsaturated fatty acids which is critical for the development of the brain and

retina which may be protected of some chronic diseases. Fin fish is an excellent source of the B

vitamin niacin (niacin assists in the functioning of the digestive system, skin and nerves. It is

important for the conversion of food to energy) and B12 (vitamin B12 is critical to building

DNA and RNA, the maintenance of the nervous system, fatty acid synthesis, homocystein

metabolism and energy production), and in general is a better source of vitamin D and A than

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beef, pork or chicken. The vitamin D is vital for the formation of bones. Fish can also contribute

appreciable amount of dietary Calcium, Iron, Zinc and nutrients that tend to be low in peoples

diets. Fish is among the best sources of dietary selenium. (Johnston, 1991).

Fin fish is a high quality protein. It contains about 19% protein that is similar in amino acid

composition to that found in muscle meats. The content varies from 1 to 20% depending on the

species and the season of the year.

Fin fish contains protein of high biological value, essential minerals, vitamins and fats. Fin fish is

also a satisfactory source of magnesium, phosphorous, iron and copper. Fin fish are excellent

source of easily digestible protein of high nutritional value. Tests have shown that 85% to 95%

of the protein is assimilable. (Abowei, 2000).

Consumption of fin fish and fishery product like fish oil has been shown to cut risk of heart

attacks by 50%. The omega-3 oil in fish can relieve symptoms of rheumatoid arthritis,

osteoarthritis, asthma, psoriasis, high blood pressure. Fish is a known anti inflammatory agent

and anti – coagulant. It also raises good type HDL cholesterol, lower triglycerides, guards

against glucose intolerance and type II diabetes. (Welcomme, 1979).

Fin fish also exhibits anti cancer activity especially in blocking development of colon cancer and

spread of breast cancer.

Fin fish contains proteins that are complete (contain all the amino acids required by the body).

To this end point, it is important to access the catch composition of fin fish in the lower Ogun

river, Ogun state in order to know the species that are present in the lower river body.

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1.2 CATCH COMPOSITION IN WATER BODY

Catch composition of a water body is the assessment of the fishery worth in the water. This can

be done by fishing in the water body at a continuous rate to sort out the various species present in

the water body.

The catch at a point in time is been separated into different species and families. This is the

assessment of species that are abundant in the water and those that are into extinction. To

determine the species that are abundant and those that are into extinction, counting of the number

of specimen per specie should be done, percentage weight of the species should be recorded and

percentage number of specimen should also be recorded.

The biomass per catching period is also noted for each species caught in the water body. Catch

per unit effort is also noted for each period of catch to determine the species that are into

extinction.

Seasonality in number and biomass by comparing the total number of fin fish caught in dry

season with the total number of fin fish caught in wet season should be recorded to properly

assess the catch composition in both seasons of the year.

1.3 OBJECTIVES

The general objective of this study is to assess the fishery potential and their abundance in Ogun

river.

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The specific objectives are to;

• Identify the most abundant species of fin fish in the river.

• Identify the species that are into extinction.

• Identify the level of fishing activities in the river.

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CHAPTER TWO

2.1 LITERATURE REVIEW

Catch composition of fin fish have been used to assess the fish abundance in a water body.

Investigations have been carried out in various locations of lower num river to assess the level of

catch in water (Abowei, 2000). Fishing in the river is intensified and catch per unit effort is

reduced, that is overfishing can reduce the total catch of the affected rivers.

Catch statistics are important in fisheries management; it becomes imperative to update some of

the existing sampling systems. The number of fish caught is the test of a fishery worth (Cowx,

1991)

Catchability did vary, but in a predictable manner and it could be assumed that the relationship

between catch per unit effort and stock level of a particular species was reasonably constant

under a given set of circumstances. Catchability of fish varies with season (Cowx, 1991).

The depth and the width of a river can also be responsible for the catchability and the abundance

of fish at a point of catch. The depth and width of a river varies slightly at different sampling

station (Sikoki et al., 1998).

The total catch landed is directly proportional to the effort of fishing and after some time of

fishing, the total catch landed will reduce drastically due to overfishing as a result of effort

applied. Due to our effort towards speedy industrialization and recreational activities, it has been

discovered that river Niger is fast degraded (Abowei, 1996).

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Fish stock assessment evaluates the effort of fishing on a fishery as a basis for fishery

management decisions (Sissenwine et al., 1979). Stratification is commonly used in conjunction

with random sampling to obtain survey data. Fish abundance, catch composition and seasonality

are measurements of fish recruitment in a fishery.

The sampling design which incorporated temporal (seasonal) and geographical stratification was

used to evaluate the artisanal fishery on the Niger River in Nigeria, West Africa (Cowx, 1991).

The fin fish composition and seasonality in a fishery, provides information on the species

checklist to assist fish managers and administrators in formulating resource development

policies.

It has been observed that fish catch can be significantly affected by the lunar periods. Federal

fisheries service Nigeria (1964) reported that catches (from gill nets, set in lake chad Nigeria)

consisting chiefly of Niger (Nile) perch, Lates niloticus tended to rise to the peak at the full

moon and during the succeeding week. Similar conclusion were reached by centre technique

forestier tropical, Coted’Ivoir (1966) from gill net catches in the south east part of the lake

(Otubusin, 1989).

Hopson (1970) also observed that catches of lates niloticus reached a peak near the full moon

during some months of the year. The catchability of heavier fish at and around full moon can be

attributed to the fish activities during these lunar periods, even though the catchability of a fish

species depends on a combination of many factors, such as mesh size, visibility of the twine and

patterns of behavior of the fish (Clark, 1960).

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The total fish catch during the period of turbid water, i.e. in the months of September-November

(transparency often less than 1metre at netting sites) was attributed to the fact that the fish could

not clearly see the static gill nets and therefore were caught (Muphy, 1959).

Fish are known to migrate towards the shoreline in search of food soon after sunset and back to

deep waters at dawn (Ita, 1978), from field observations, confirmed lateral migration of some

adult fish species, especially in families Citharinidae and Cichlidae, both of which are

planktivores common in inshore habitat in lake Kainji from deeper waters towards the shore

possibly associated with feeding and breeding habits. This migratory movement could account

for the greater amount of fish caught in the parallel set compared with the perpendicular set.

The littoral zone has often been linked with feeding and breeding activities. The lacustrine

regime established in lake kainji has increased the extent of the shore habitat (Lelek and El-

Zarka, 1973). This region (shore habitat) serves as the breeding ground for the majority of

commercial fish species in the lake as evidenced from the results of shoreline sampling of

juvenile fish with electric shocker (Ita, 1973).

This reason could therefore be suggested for the greater total fish catch (CPUE, number and

weight) observed in the shore fleet than in the surface fleet. As bigger fish often prefer deeper

waters, the observation that bigger fish were caught in the surface fleet was not surprising

(parrsish (1963)) suggested that as different sizes of fish may occupy different habitats, the size

caught may depend on the location and depth of fishing.

Fish found in tropical and sub-tropical water system experience frequency growth fluctuations

due to factors such as food composition changes, environment changes, rate of spawning to

mentioned but a few, length weight and length-length relationship can be used to assess the

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influence of these factors in fish (Kulbicki et al, 1993). King, R. P. (1996) reported that fish

growth, mean weight of a given body length of a fish estimation and the relative well being in

fish can be known through this relationships length-weight, length-length relationships studied

have been done in different water bodies and on different fishes.

Oreochromis niloticus is a fast growing and highly prolific species, through an indigenous Africa

fish. It is also an intercontinental traveler (Bardach, et al.,1972). It has high tolerance to

environmental conditions and its ability to accept compounded and natural feeds makes it

economically cultivable and viable.

The surface of water covered by typha grass prevent light penetration, excessive development of

algae bloom also causing nuisance in cultivated fish ponds and small reservoirs. They even cause

fish mortality due to oxygen depletion or release of extra-cellular metabolites which are toxic

(Patriaik, S.1980).

According to (Bennet, F. D. 1974) “There is evidence that dense strends of typha grass may wind

up nutrient materials throughout the growing season so that they are not available for production

of phytoplankton and the organisms that feed upon phytoplankton” This means that although fish

hatches would be large, the chances of larva survival would be greatly diminished.

A number of natural and manmade lakes in Nigeria are picturesque and most of them are utilized

for human consumption, irrigation and power generation purposes (Kainji, Jebba, Shiroro).

However, increasing anthropogenic activities in the past few decades have greatly affected the

hydrological regime of the lakes. Consequently, inflow of eroded materials and other

contaminants from the catchments has accelerated the rate of sedimentation and euthrophication

processes. Sedimentation processes within wetlands are intimately connected with many wetland

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functions, the most important effect of which is the influence on water quality (Johnston, 1991;

Gulliam, 1994; Mitsch and Gosselink, 2000).

Since wetlands function as sources, sinks and transformers of materials, they have the potential

to positively or negatively affect water quality by trapping or transporting excess nutrient,

harmful chemical and other high material loads. Low water velocities cause wetland to act as

depositional environments for sediments suspended in water, and thus for nutrients and other

chemicals sorbed to sediments (Phillips, 1989).

Moderate levels of sediment deposition can lead to increased vertical growth relocating the

meristems (growth centre) closer to the sediments such that the photosynthetic portions are

located in the proper light regime and effective gas exchange may occur. Suspension of

unconsolidated deposited sediments has been hypothesized to cause the decline of sea grass

habitat. Altered substance surfaces from dredge and fill operations may reduce the quantity of

photosynthetically active radiation (PAR) available to submerged aquatic macrophytes and other

aquatic plants (Onuf, 1994; Dawes et al, 1995; Tomasko et al, 1996).

Berry et al (2003) stated that adults and juveniles of most species of fish avoid areas of

temporary high sedimentation and return at a later time, eggs of bottom spawning species,

survival of larval stages living in and around the substratum, and in substratum sediment

composition as well as demersal or non buoyant eggs that may either remain adhered to

spawning sites or be carried by bottom currents are additionally exposed to sediment action and

burial (Lasalle et al 1991).

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Cast nets fishing is regarded as a traditional method of catching fish that has been used since

antiquity. The most widely used artisanal fishing gears in Nigerian freshwater and brackish water

as well as coastal water, are gill nets and cast nets (FAO, 1969).

Cast net are conical falling nets with lead (Pb) weights attached at regular intervals along the

perimeter of the cone (Udolisa and Solarine, 1979). It is an active fishing gear, which catches

fish instantly.

Hayes et al (1996) reported that a light or bait is often used to attract the target fish into an area

within the cast net’s range. Fishing baits lures and attraction devices are often incorporated into

some fishing gears in order to improve their efficiency. Such fishing gears include handlines,

longlines, trolling and traps e. t. c. (Ahmed et al, 2005).

Baits may include rotten meat, dead or life fish, palm nuts or corn bran depending on the feeding

and behavioral characteristics of the target fish species. The cast net fishery is probably the next

most damaging fishing method to juvenile after beach seine (du Feu and Abiodun, 1999). It

caught 34% of the total tilapines, 24% Citharinus and 19% of all Labeo, at a mean size up to

50% less than gillnets in the case of citharinus.

2.2 PROBLEMS ASSOCIATED WITH LOW CATCH COMPOSITI ON

The problem encountered with low catch composition of a water body is a National problem.

Low catch composition will result to insufficient fin fish in the market which will in turn leads to

increase in the price of the limited available ones.

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Another problem is inability to assess low cost protein food like fish by the children and adult.

As a result of scarcity of fin fish caused by low catch composition, fishery product like fish oil,

fish meal e.t.c. would also be limited in the market.

Low catch composition also discourage some fishers to leave their fishing work for another

profitable one like farming during the period of low catch to be able to feed and provide for their

family.

Low catch composition which can be caused by overfishing and the type of mesh sizes used for

fishing over the years can result into less fish in the market.

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CHAPTER THREE

3.1 STUDY AREA

The study was carried out in the lower Ogun River, Akomoje in Abeokuta Ogun state. The river

is located at Abeokuta North Local Government of Abeokuta and lies between longitude 3021’S

and latitude 7021’E North of Abeokuta with a size of 1000hectares.

Ogun River as a perennial river in Nigeria has a coordinate of 3028’E and 8041’N from its source

in Oyo State to 3025’E and 6035’N in Lagos state where it enters Lagos Lagoon.

The dry season lasts from November to March while the wet season lasts from April to October.

The annual rainfall ranges from 900mm in the North of the River to 200mm towards the South.

Total annual potential evapotranspiration is 1600mm and 190mm.

The Ogun river catchment is located in South West Nigeria, bordered geographically by latitude

6026’N and 9010’N and longitude 2028’E and 404’E. The land is about 230km2. The relief is

generally low, with the gradient in the North-south direction.

Ogun River takes its source from the Igaran hills at an elevation of about 540m above the sea

level and flows directly southward over a distance of 480km before it discharge into the Lagos

Lagoon. The major tributaries of the river are Ofiki River and Opeki River.

3.2 FISH SAMPLING

Data on fish species were collected twice per month using gillnet, cast net, long lines, hooks and

cages. Three sampling stations were randomly selected. This technique involved sampling of

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each station for the fish composition and abundance using cast net of 50.8mm mesh size and

other fishing gear which were done simultaneously in the various sampling stations.

The sampling regime for each sampling day was five hours for a period of 5 months covering the

end of dry season to the beginning of raining season from January to May 2011. The sampling

involved purposive selection of four hydrological stations with substantial fishing activities.

Fleets of gill nets, lure and other fishing gear were set at dusk and retrieved at dawn in all

stations. The nets were set at different ecological zones in open water, flooded bush pateries and

shallow bays.

The number and weight of fish in each station was measured. The weight of each fish was

obtained by weighing samples on a digital mettle balance to the nearest 0.01kg. fish samples

were counted, sorted out and identified using freshwater identification checklist by NIFFR

(Olaosebikan, B. D. and Aminu, R. (2004)).

3.3 PHYSICO–CHEMICAL PARAMETER

Monthly rainfall data were obtained from the meteorological Department of Ogun State Water

Corporation, Ogun State. Surface water temperature was measured 2 minutes after dipping

mercury – in – glass thermometer at a depth of 5.0cm below the surface water. Depth

measurement were made using a graduated rope attached to a lead sinker, lowered from a canoe

into the floor of the water. The average depths were recorded after the whole sampling.

Water velocity was measured with a floating object to move pass 2 fixed points was recorded.

The water velocity was calculated and expressed as the time taken in seconds to flow through

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one meter. Conductivity was measured using a portable meter (Model WTW LF 90), while P.H.

was measured using (Model WTW PH 90) meter. Total dissolved solids (TDS) were measured

directly with the Lovibond Tintometer. The dissolved oxygen content was determined using Oxy

– Guard Model MK – 11 field oxygen meters. Transparency was measured directly using a

secchi disc. Salinity was measured with a salinometer (Antergo, 28). In taking the salinity, a drop

of the test water was placed on the lens of the instrument and allowed to remain for five minutes.

The salinity of the water was then read through the eyepiece. The results of the field experiments

were corroborated with the results of laboratory analysis of the physicochemical parameter.

Figure 1 - An open water body of the project site

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Figure 2 - Depth controlling guage

Figure 3 – A map showing Ogun River

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CHAPTER FOUR

4.0 RESULTS

The results of the physical and chemical characteristics are presented in Table 1. Hydrogen ion

concentration (PH) values ranged from 8.53 + 1.08 to 8.59 + 1.14. The mean temperature of the

surface water ranged from 26.9 + 2.9oC to 27.40 + 3.3oC. The mean dissolved oxygen (DO)

values ranged from 4.58 + 0.46mg/l to 4.72 + 0.6mg/l. The mean alkalinity values ranged from

8.75 + 4.25mg/l to 10.00 + 4.5mg/l. The mean phosphate values ranged from 0.18 + 1.15mg/l to

0.25 + 0.17mg/l. The mean nitrate values ranged from 2.63 + 2.39mg/l to 2.86 + 2.58mg/l. The

mean water depth values ranged from 1.63 + 0.61m to 3.48 + 0.4m. The mean transparency

values ranged from 0.70 + 0.16m to 0.77 + 0.24m. The mean rainfall was 200.00mm and was

uniform in all sampling stations. Mean conductivity values ranged from 160 + 20s/cm to 170 +

20s/cm. Total dissolved solid values ranged from 80 + 10mg/l to 85 + 10mg/l. Water velocity

ranged from 12.50 + 0.39cm/s to 19.63 + 0.57cm/s.

Table 1 – Physical and chemical characteristics of fresh water reaches of lower Ogun River,

Akomoje.

PARAMETERS STATION 1 STATION 2 STATION3

PH 8.59 + 1.14 8.56 + 0.84 8.53 + 1.08

Water Temperature (oC) 27.40 + 3.3 27.34 + 3.35 26.9 + 2.9

Dissolved Oxygen (mg/l) 4.72 + 0.6 4.67 + 0.54 4.58 + 0.46

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Alkalinity (mg/l) 8.75 + 4.25 9.50 + 5.00 10.00 + 4.5

Phosphate (mg/l) 0.22 + 0.20 0.18 + 1.15 0.25 + 0.17

Nitrate (mg/l) 2.86 + 2.58 2.63 + 2.39 2.75 + 2.47

Depth (m) 3.48 + 0.4 1.63 + 0.61 2.45 + 1.43

Transparency (m) 0.77 + 0.24 0.70 + 0.16 0.75 + 0.22

Rainfall (mm) 200.00 200.00 200.00

Conductivity (s/cm) 170 + 20 160 + 20 165 + 25

Total Dissolved Solid 85 + 10 80 + 10 82.5 + 12.5

Water velocity (cm/s) 12.50 + 0.39 12.53 + 0.71 19.63 + 0.57

Table 2 represents the fish species composition in the fresh water reaches of the lower Ogun

River. A total of 41 species from 11 families were caught during the study period. . Mormyrus

rume was highest in biomass (62kg) accounting for 8.26% of the catch, while Brycinus

macrolepidotus was most numerous (144) accounting for 17.5%. Bagrus bayad, Sarotherodon

melanotheron, Nannocharax ansorgii and Synodontis sorex were the least in bimass (0.2kg)

accounting for 0.12%. while Bagrus bayad, Parachanna obscura, Sarotherodon melanotheron,

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Garra waterloti, Barbus occidentalis, Barbus callipterus, Nannocharax ansorgii, Mormyrus

macrophthalmus and mormyrus hasselquistii were the least in number.

Table 2 – Fish species caught and their percentage composition of fresh water reaches of lower

Ogun River, Akomoje.

S/N FAMILIES AND SPECIES NO OF

FISH

SPECIMEN

% NO OF

SPECIMEN

WEIGHT

(kg) OF

SPECIMEN

%

WEIGHT

OF

SPECIMEN

BAGRIDAE

1. Bagrus filamentosus 4 0.49 0.60 0.28

2. Bagrus bayad 1 0.12 0.20 0.09

3. Chrysichthys auratus 27 3.28 1.90 0.88

4. Chrysichthys nigrodigitatus 137 16.65 20.74 9.65

5. Chrysichthys aluuensis 2 0.24 1.00 0.47

CENTROPOMIDAE

6. Lates niloticus

15 1.82 39.80 18.51

CHANNIDAE

7. Parachanna obscura

1 0.12 0.25 0.12

CHARACIDAE

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8. Brycinus baremoze

22 2.67 8.20 3.81

9. Brycinus dentex

20 2.43 5.40 2.51

10. Brycinus leuciscus

2 0,24 2.40 1.12

11. Brycinus macrolepidotus

144 17.50 13.10 6.09

12. Brycinus brevis 6 0.73 0.90 0.42

13. Brycinus nurse 26 3.16 5.80 2.69

14. Hydrocynus forskalii 7 0.85 2.25 1.05

CICHLIDAE

15. Tilapia dageti 60 7.29 6.20 2.88

16. Tilapia mariae 90 10.94 10.10 4.69

17. Tilapia zilli 9 1.09 1.20 0.56

18. Hemichromis fasciatus 18 2.19 1.30 0.61

19. Oreochromis niloticus 31 3.77 5.40 2.51

20. Sarotherodon melanotheron 1 0.12 0.20 0.09

CLAROTEIDAE

21. Clarotes laticeps 14 1.70 1.25 0.58

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CYPRINIDAE

22. Garra waterloti 1 0.12 0.30 0.14

23. Labeo parvus 6 0.73 0.70 0.33

24. Labeo senegalensis 2 0.24 0.40 0.19

25. Barbus occidentalis 1 0.12 0.30 0.14

26. Barbus callipterus 1 0.12 2.00 0.93

DISTICHODONTIDAE

27. Distichodus rostratus 3 0.36 1.50 0.69

28. Distichodus brevipinnis 4 0.49 0.50 0.23

29. Distichodus engycephalus 42 5.10 4.45 2.07

30. Nannocharax ansorgii 1 0.12 0.20 0.09

MOCHOKIDAE

31. Synodontis clarias 10 1.22 0.90 0.42

32. Synodontis omias 8 0.97 1.70 0.79

33. Synodontis sorex 3 0.36 0.20 0.09

34. Synodontis budgetti 15 1.82 1.95 0.91

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35. Brachysynodontis batensoda 9 1.09 2.00 0.93

MALAPTERURIDAE

36. Malapterurus electricus 2 0.24 0.30 0.14

MORMYRIDAE

37. Mormyrus rume 68 8.26 62 28.84

38. Mormyrus tapirus 6 0.73 5.80 2.69

39. Mormyrus macrophthalmus 1 0.12 0.30 0.33

40. Mormyrus hasselquistii 1 0.12 0.30 0.14

41. Mormyrops anguilloides 2 0.24 0.60 0.28

TOTAL 823 100 214.99 100

The weekly biomass (kg) and number of fish caught during the study are presented in table 3.

The results show that the peak biomass was recorded in January, week 1 (40.65kg), accounting

for 18.91% of the total weekly biomass. The highest number (176) accounting for 21.39% of the

total number of fish was recorded in April, week 8.

32

Table 3 – weekly biomass and number of fish caught in lower Ogun River

WEEKLY NUMBER

OF FISH

PERCENTAGE

NUMBER OF FISH

WEIGHT OF

FISH (kg)

PERCENTAGE

WEIGHT OF FISH

(kg)

1 55 6.68 40.65 18.91

2 80 9.72 25.00 11.63

3 85 10.33 26.85 12.49

4 58 7.05 13.50 6.28

5 58 7.05 20.30 9.44

6 38 4.62 29.45 13.70

7 152 18.47 17.25 8.02

8 176 21.39 23.70 11.02

9 62 7.53 7.94 3.69

10 59 7.17 10.35 4.81

Total 823 100 214.99 100

33

Table 4 shows the monthly catch, fishing effort and catch per unit effort for fish caught in the

study area. The results revealed that catch per unit effort was highest in January, week 1

(8.13kg/hr) and lowest in May, week 9 (1.58kg/hr)

Table 4 – weekly catch (kg), fishing effort and catch per unit effort for fish caught in the lower

Ogun River.

WEEKLY CATCH (kg) FISHING EFFORT (hours) CATCH PER UNIT EFFORT

1 40.65 5 8.13

2 25.00 5 5.00

3 26.85 5 5.37

4 13.50 5 2.70

5 20.30 5 4.06

6 29.45 5 5.89

7 17.25 5 3.45

8 23.70 5 4.74

9 7.94 5 1.58

10 10.35 5 2.07

34

Total 214.99 50 42.99

Figure 4 –Bar chart representation of Catch statistics in kilogram

.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

Catch 1 Catch 2 Catch 3 Catch 4 Catch 5 Catch 6 Catch 7 Catch 8 Catch 9 Catch 10

Catch statistics of lower Ogun River in

Kilogram

35

Figure 6 – Some of the catch at the sampling station

36

CHAPTER FIVE

5.0 DISCUSSION

The lower Ogun River contains different kinds of fish species. Various sampling stations and

fishing gear were used to ensure comprehensive samples of fish species from the study area. A

total of 823 fish specimens were caught between January to May 2011 from the study area.

These were identified and classified into 41 species of fish representing 11 families. This species

composition was lower than the results of other studies in other water bodies. Lowe –

McConnell, (1964) encountered 44 species on the Rupennine River. Okereke (1990) in her study

of Otamiri River Imo State recorded 46 species in 20 families. Other comparable study results

include: Sydenham, 1979 of Ogun River (85 species), Victor and Tetteh (1988) 58 species from

Ikpoba River, Imevbore and Okpo (1975) 70 species from River Niger.

The 41 species of fish encountered in this study was however higher than the number recorded

by Alfred – Ockiya (1998) in Kolo Creek (11 species), Nweke (1984) in Aba River (29 species),

Sydenham (1975) in Odo – ona stream (13 species) and Ekeh (1990) in Nworie River (19

species). The abundance of Brycinus macrolepidotus and commonness of Chrysichthys

nigrodigitatus in this study could be attributed to their ability to tolerate low levels of oxygen

and inability to neither bury themselves nor burrow into the muds. The result of the study shows

that Lower Ogun River consists of numerous fish species.

The variation in number of species may be explained in three ways: Differences in the physical

and chemical conditions cause variations in species composition. Low diversity is a function of

low productivity which has been a common feature of small fresh water Rivers. (Welcomme,

1979). The hypothesis states that high diversity would indicate places of unpredictable hazards or

37

places that would be short lived. Only time would prove neither how unpredictable nor short

lived the lower num River would be. The difference in the species composition in this study and

others may be due to difference in abiotic factors such as temperature, pH, turbidity, dissolved

oxygen, conductivity, salinity, alkalinity and nutritive salts. For instance surface water

temperature exhibited seasonal variation. pH was neutral to slightly alkaline during the study

period.

The results from the study show that lower Ogun River consist of fish species that can be

compared favourably with other fresh water bodies. This information can be used for

management decisions and formulation of resource development in the area in addition to the

provision of a checklist for fisheries study. The variation in number of species may be explained

in two ways: Differences in the physical and chemical conditions cause variation in species

composition. Low diversity is a function of low productivity which has been a common feature

of small fresh water rivers (Welcomme, 1979).

5.1 CONCLUSION

In this study, the knowledge of fish catch statistics has contributed to the understanding of the

population structures of these species in lower Ogun River, Arakanga Reservoir, Akomoje,

Abeokuta, Ogun State. It has provided useful information on the optimum exploitation of these

fish species.

The total of 144 fishes analysed has 13.10kg with Brycinus macrolepidotus having the highest

percentage of 17.50% and Bagrus bayad having the least catch percentage of 0.12%.

38

From the study, the fish species harvestable from this water body are low in population. This has

great implication on the stock in the fishery and can also act as an indicator of over – exploitation

of these species.

5.2 RECOMMENDATION

More studies on catch statistics of fin fish in the water bodies of the world should be encouraged

for better overview of these parameters for other species in this water body for the knowledge of

growth and population dynamics.

Detailed study on species composition of this water body is essential to help in the sustainable

utilization of its resources.

Research into physicochemical parameters of this water will help greatly in biological

assessment of various fish species and other aquatic fauna present therein.

39

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