tilapia cage culture in rwanda current status and prospects of future development

NHA TRANG UNIVERSITY Institute of Aquaculture Fidele KAMPAYANA 54CH345 Tilapia cage culture in Rwanda: Current status and prospects of future development... MINISTRY OF EDUCATION AND

NHA TRANG UNIVERSITY Institute of Aquaculture

Fidele KAMPAYANA

54CH345

Tilapia cage culture in Rwanda:

Current status and prospects of future development

Master’s Thesis

Nha Trang, July 2014

MINISTRY OF EDUCATION AND TRAINING

NHA TRANG UNIVERSITY Institute of Aquaculture

Fidele KAMPAYANA

54CH345

Tilapia cage culture in Rwanda:

Current status and prospects of future development

Thesis for partial fulfillment of Master of Science in Aquaculture

NTU, July 2014

Declaration

I hereby declare that this is my original work and has not been produced elsewhere for the award of a Masters in Aquaculture Science Where other people’s ideas have been used, they have duly been acknowledged

Fidele KAMPAYANA

Acknowledgement

For this opportunity I would like to express my heartfelt gratitude to all those that supported me from the start of this thesis until the last minute Surely, without your contributions, this research could not be accomplished

So, I say thank you to my supervisors, Le Minh Hoang, Ph.D Lecturer in Nha Trang University and Sy Nguyen Tan Ph.D, the Vice Director of Aquaculture Institute in Nha Trang University/Vietnam for their advice and thoughtful contributions towards the accomplishment of this thesis I must admit that with their guidance, writing this thesis was made much easier The Director of Aquaculture Institute in Nha Trang University and particularly all lecturers of Aquaculture Master Class for their timely advice and encouragement

In a special way I thank the Director General of RAB/MINAGRI and particularly the Fisheries and Aquaculture Program Manager, Dr Wilson RUTAGANIRA for accepting

me into their group members and for providing me all facilities and services needed for this research I am grateful to all Fisheries and Aquaculture Officials in lakes Burera, Kivu, Muhazi and Ruhondo for accepting to work closely with me during my fieldwork Thank you for the reports and facilities you rendered I also acknowledge the support got from all respondents of this survey and interviews Thanks for the information, data and facilities you provided

I wish to say “Com on” to all Vietnamese comrades for the comfortable accommodation offered to me during my stay in their lovely country “Viet Nam” and my fellow course mates who were supportive as we struggled together I also acknowledge the moral support of my family members, friends and relatives both in Rwanda and in Vietnam

Finally, the AfDB through SFAR education loan fund for the scholarship awarded for my Master courses

Fidele KAMPAYANA

Dedication

I dedicate this thesis to my last born daughter IZERE IGENA Darlene, my first son IZERE IGABA Dharna and my beloved UWUMUKIZA Clarisse; mother of my two children

Table of contents

Page

Declaration I

Acknowledgement ii

Dedication iii

Table of contents iv

Abstract vii

List of acronyms viii

List of graphs, figures and pictures IX List of tables X INTRODUCTION 1

Background information 1

Statement of the problem 2

Justification of the study 3

Objectives of the study 4

Hypotheses 4

Main parts of the thesis 4

CHAPTER 1: THEORETICAL FRAMEWORK AND CAGE CULTURE CONCEPTS 5

1.1 Historical and global overview of fish cage culture 5

1.2 Advantages and disadvantages of cage culture 7

1.2.1 Advantages 7

1.2.2 Disadvantages 8

1.3 Tilapia; Cage cultured species of choice 9

1.4 Cage design and construction 10

1.4.1 Classification of cage design and construction 10

1.4.2 Components of cage design and construction 12

1.4.3 Site selection and carrying capacity of cage culture 13

1.4.4 Classification of cage culture according to different management systems 16

1.5 Management practices of fish cage culture 17

1.5.1 Fish seed and stocking practices 17

1.5.2 Feeds and Feeding 19

1.5.3 Stock sampling 21

1.5.4 Harvesting 21

1.5.5 Cage maintenance and monitoring 22

1.5.6 Record keeping 22

1.6 Cage culture economics 23

1.6.1 Production costs 23

1.6.2 Returns 24

1.6.3 Break-even price 25

1.6.4 Market identification 25

CHAPTER 2: STUDY DESIGN AND METHODOLOGY 26

2.1 Scope and duration of the study 28

2.2 Survey 28

2.3 Interviews 29

2.4 Field studies and personal observations 29

2.5 Data analysis 29

CHAPTER 3: RESULTS AND DISCUSSIONS 30

3.1 Characteristics of the study area 30

3.1.1 Characteristics of Rwanda 30

3.1.2 Characteristics of the potential zones for tilapia cage culture 31

3.2 Current status of Tilapia cage culture in Rwanda 36

3.2.1 Characteristics of tilapia cage operators 36

3.2.2 Characteristics of Tilapia cage farms 40

3.2.3 Management practices 45

3.2.3.1 Site selection and environmental monitoring 45

3.2.3.2 Seed supply and stocking practices 47

3.2.3.3 Cage inspection and maintenance 50

3.2.3.4 Stock sampling and fish manipulations 51

3.2.3.5 Feed supply and feeding practices 53

3.2.3.6 Harvesting practices and marketing system of harvested fish 55

3.2.3.7 Economic analysis of the current tilapia cage production in Rwanda 57

3.3 Perception of cage operators on the current and future prospects of tilapia cage culture industry 60

3.3.1 Appreciation of current productivity of tilapia cage culture 60

3.3.2 Constraints and problems of current tilapia cage culture in Rwanda 61

3.3.3 Needs for future development of Tilapia cage culture in Rwanda 64

CHAPTER 4: CONCLUSION AND RECOMMENDATIONS 67

4.1 Conclusion 67

4.2 Recommendations for prospects of future development of tilapia cage industry 67

References 69 Appendices I

Abstract

The present study was conducted in order to contribute to the future development of tilapia cage culture industry in Rwanda by reviewing the current production system and its constraints and then propose possible solutions to overcome them In order to obtain the results of this research, 52 formal questionnaires have been personally administrated

to 52 tilapia cage operators (total population) In addition to the formal questionnaire, 28 in-depth interviews have been conducted with potential key informants in order to have insight into the constraints of tilapia aquaculture development as well as the solutions that can be considered to promote the future commercial tilapia cage aquaculture adoption in Rwanda The findings of this study revealed that 52 tilapia cage operators are located in four lakes (Kivu, Ruhondo, Burera and Muhazi) and grouped into 23 tilapia cage-based parks A total of 656 floating cages were numbered in all parks; 80.5% of them were not restocked (empty cages) due to many reasons provided by the operators such as lack of funds to buy feed, lack of fingerlings and fear of high mortality rate The stocking density

by most of the operators was ranged between 1,500 to 2,000 tilapia fingerlings of 10 to

50 g average weight per cage of 8m3 The harvest size of fish after 8 to 9 months of grow out was approximated by most of the operators at 4 fish per kg (equivalent to 250g average weight) During culture period, fish were fed twice or thrice a day with imported floating pellet of 25 to 35% of protein content The shortage of tilapia fingerlings, high cost of quality feed and high mortality rate of fish were the major factors that affected current tilapia cage production Most of the operators did not undertake more innovative and adequate management practices such as optimum stocking, stock manipulations, sexing and grading, disease control and prevention, records keeping on inputs and outputs

of the cage culture operations due to lack of knowledge and know-how skills However, seed and feed production at farm and local levels, training and extension program based

on research and technological innovation were highly suggested by most of the operators

as main ways towards sustainable development of tilapia cage culture industry in Rwanda

List of acronyms

AfDB: African Development Bank

BCEOM: Central Bureau for Overseas Equipments Studies (Bureau Central d’Etudes

pour les Equipements d’Outre Mer)

BMPs: Best Management Practices

DO: Dissolved Oxygen

DVO: District Veterinary Officer

EAC: East African Community

EIA: Environmental Impact Assessment

FAO: Food and Agriculture Organization of United Nations

FCR: Feed Conversion Ratio

GoR: Government of Rwanda

IFOM: International Federation of Organic Agriculture Movements

LVHD: Low Volume High Density

MINAGRI: Ministry of Agriculture and Animals Resources

MST: Mixed Sex Tilapia

NGO: Non Government Organization

NTU: Nha Trang University

PAIGELAC: Projet d’Appui à l’Aménagement Intérgé et à la Gestion des Lacs

Interieurs (Inland Lakes Integrated Development and Management Support Project)

RAB: Rwanda Agriculture Board

RAS: Recirculation Aquaculture System

SFAR: Student Financing Agency for Rwanda

SRT: Sex Reversed Tilapia

VTS: Vocational Training School

List of graphs, figures and pictures

Page Figure 1.1: Principal components of floating cage described by Vázques [28] 12 Figure 2.1: Schematic diagram of the contents 26 Figure 2.2: Schematic diagram of the study design and methodology 27 Figure 3.1: Rwanda map showing a hydrological network

(Source:http:// www.rema.gov.rw/soe/ chap7.pdf) 30 Figure 3.2: Map of Lake Kivu (source: Fisheries and Aquaculture Master Plan, 2011) 32 Figure 3.3: Map of Burera and Ruhondo

(source: Fisheries and Aquaculture Master Plan, 2011) 33 Figure 3.4: Map of lake Muhazi (source:

Fisheries and Aquaculture Master Plan, 2011) 34 Figure 3.5: Repartition of tilapia cage operators in lake kivu, Ruhondo,

Burera and Muhazi Rwanda, 2014 37 Figure 3.6: Organization of tilapia cage operators in lakes Kivu, Ruhondo,

Burera and Muhazi Rwanda, 2014 37 Figure 3.7: Reasons of tilapia cage culture adoption by 52 operators in Rwanda, 2014 39 Figure 3.8: Repartition of tilapia cages in lakes Kivu, Ruhondo, Burera,

Ruhondo and Muhazi Rwanda, 2014 41 Figure 3.9: Photo of cage farm unit taken at the time of the field visits

in lake Kivu, 2014 42 Figure 3.10: Repartition of tilapia cage farm size among 52 operators in lake Kivu,

Ruhondo, Burera and Muhazi Rwanda, 2014 43 Figure 3.11: Frequency of water quality monitoring 46 Figure 3.12: Climate changes and natural calamities affecting tilapia cage culture

in lake Kivu, Ruhondo, Burera and Muhazi Rwanda, 2014 47 Figure 3.13 : Valuation of current tilapia cage culture productivity

among 52 respondents 61 Figure 3.14: Constraints affecting current tilapia cage culture production

in Rwanda, 2014 62 Figure 3.15 : Solutions suggested for the current constraints of tilapia cage culture

by 52 tilapia cage operation in Rwanda, 2014 65

List of tables

Page

Table 1.1: Classification of cage design and construction based on technical

characteristics 11 Table 1.2: Recommended daily feeding rates, expressed as the percentage of body

weight, for Tilapia of different sizes 20 Table 3.1: Physicochemical parameters of Lakes Burera and Ruhondo

(Source: BCEOM report 2008) 34 Table 3.2: Physicochemical parameters of Lake MUHAZI

(Source: BCEOM report 2008) 35 Table 3.3: Background information on 52 tilapia cage operators in Rwanda, 2014 38 Table 3.4: Number of cage-based parks, units and cages identified in lake Kivu,

Ruhondo, Burera and Muhazi Rwanda, 2014 42 Table 3.5: Stocking density, size and source of fingerlings among 52 tilapia cage

operators in Rwanda 2014 49 Table 3.6: Frequency of cage inspection and cleaning in lake Kivu, Ruhondo,

Burera, and Muhazi Rwanda, 2014 50 Table 3.7: Frequency of fish sampling and stock manipulation purposes 52 Table 3.8: Type of fish feed used by 52 tilapia operators in Rwanda, 2014 54 Table 3.9: Frequency of daily feeding and feeding rate estimation methods

used by 52 cage operators in lake Kivu, Ruhondo, Burera and Muhazi Rwanda 2014 55 Table 3.10: Harvesting practices and marketing system of cage produced tilapia

by 52 operators in Rwanda, 2014 56 Table 3.11: Production parameters calculated for farm unit of 10 tilapia cages 58 Table 3.12: Economic indicators calculated for cage farm unit of 10 tilapia cages 59

INTRODUCTION

Background information

The aquaculture sector has increasingly played a vital role in meeting the growing global demand for food [9] This role has internationally widely recognized in recent years Cage aquaculture subsector has grown very rapidly during the past 20 years and is presently undergoing rapid changes in response to pressure from globalization and growing global demand for aquatic products [12]

Aquaculture, which is broadly defined as the culture of finfish and shellfish in water systems is rapidly expanding in both size and culture systems and is therefore among the fastest growing industries, second to biotechnology In 2009 Das, Vass et al [6] defined aquaculture as the rearing fish and others aquatic organisms in the man-made ponds, reservoirs, cages or other enclosures in lakes and coastal waters Cage culture is when fish are reared in from fry to fingerlings, fingerlings to table size or table size to marketable size while captive in an enclosed space that maintains free exchange of water with the surrounding water body [6] Fish can be also cultured in one of the four culture systems; ponds, raceways, recirculation and cages systems [16]

Rearing fish in suspended cages in reservoirs, rivers or lakes is a practice relatively new

in many parties of continents Fish cage culture dates back in 18th century and were likely used by fishermen as holding structure until fish could be accumulated for market The first true cages for producing fish were developed in the Southeast Asia around the end of

19th century [16], [2], and [10] In recent years, cage culture has spread throughout the world to more than 35 countries in Asia, America, Africa and Europe By 1977, more than 70 species of fresh water fish have been experimentally grown in cages [11] Today cage culture is practiced in many regions in the world and is a thriving industry in some areas Tilapia cage culture is the most freshwater cultivation practice which has contributed substantially to livelihood, food demand and poverty alleviation

Cage culture researches have been limited because of mostly large scale open pond culture system was considered more economically viable, and therefore, receiving more attention in research However, factors such as increasing fish consumption, declining wild fish stocks, and a poor farm economy have produced a strong interest in fish production in cages by both researchers and commercial producers [12] The present

studies entitled “Tilapia cage culture in Rwanda; Current status and prospects for future

development” aimed to review the current situation of cage culture in Rwanda and the

main constraints which may impede its future development

Statement of the problem

With national population expansion, the demand for fish is steadily increasing and natural fish production have declined during the last decade due to environment degradation and overfishing [27] Tilapia cage culture, most popular freshwater cultivation practice is highly recommended in almost Rwanda water bodies due to its substantial contributions

to livelihoods, food demand and poverty alleviation [20] Despite its socio-economic importance, actually cage culture is almost none existing in Rwanda water bodies whereas the country is blessed with an abundance of scattered inland water mass comprising of lakes, reservoirs, ponds, streams and rivers which the total surface estimated is 210,000 hectares

Since 2000, Tilapia cage culture practice has been successfully tried and frequently demonstrated in Rwanda Unfortunately, after the period of first trials, this new aquaculture technique had have not expanded and all infrastructures completely had depleted without any trace The practice is still remaining at the experimental and demonstration levels

For over the decade it has not yet translated to large scale, either on commercial or subsistence levels despite many supporting projects Meanwhile, the present study avails

to clarify the current situation of cage culture and its prospect by looking on the causes which stunting a sustainable growth of cage culture industry in Rwanda

Justification of the study

For supplying an increase fish demand, Rwanda is straggling to reach the level of Saharan fish per capita consumption of 6.7 kg per person per year while Rwandan annual fish consumption is still at 1.5 kg per caput However, national fish production stands at only 13,000 metric tons of annual fish production whereas capture fisheries contribution

sub-is 9,000 metric tons and only 4,000 metric tons sub-is aquaculture production [20] Despite the dormancy of fish farming in Rwanda during and nearly after the tragedy of 1994, MINAGRI under PAIGELAC project has revitalized aquaculture sector since 2006 by providing material and technical support to fish farmers Since 2010, Tilapia cage culture pilots and demonstration projects were reinitiated in selected potential water bodies, until now, no scientific study has been conducted on them

Tilapia cage culture production systems appear to be well-suited for adoption by both small and large scale producers because the initial capital investment is not high Because

of declining catch and catch per effort of numerous Rwandan lake fisheries, large numbers of small-scale fishermen have to be attracted to cage culture systems where the investment required is comparable to that of a fishing unit The increased production resulting from all these enthusiasms will have impacts on animal protein supply and will respond considerably to stead fish demand in the country

Because of the project potential for generating income to no land or poor farmers and protein to consumers, the present study has been chosen to review the current status of the initiated tilapia cage culture projects and to draw a persuasive baseline to new investors for profit maximization and technology transfer to overall local communities based on the experience of previous adopters Possible constraints to further expansion of cage culture in Rwanda are also needed to be identified

Objectives of the study

The main goal of this study is to contribute to future development of Tilapia cage culture

in Rwanda; through identification of technical and socio-economic limitations for adoption and expansion of this new technology Specifically, the present study has the following specific objectives:

- To identify the current production systems of Tilapia cage culture in Rwanda

- To identify all problems affecting Tilapia cage culture production in Rwanda,

- To propose possible solutions to overcome the hindrances for further expansion of Tilapia cage culture industry in Rwanda

Hypotheses

Fish cage culture is not common practice in Rwanda water bodies It is relatively a new technology, though most of the farmers and other investors are still reluctant to get involved The most likely reasons for the failure to entirely popularize cage culture in all national water bodies are in one hand, the production systems currently applied could not lead to profit maximization and in the other hand, a lack of farmer’s hands-on knowledge and skills would be a key constraint to cage culture industry development in Rwanda

Main parts of the thesis

This study is present into five chapters; the first chapter is the introduction which provides the general background on cage culture, the problem statement of tilapia cage culture in Rwanda, the justification of this subject, and finally the objectives and hypothesis of the study The second chapter is a literature framework which describes the concept of tilapia cage culture The third chapter shows the design of this study and describes the methodology used for this study in order to achieve its objectives The forth chapter presents the results and discussions which are closed with the last chapter of conclusion and recommendations resorted from the findings of this study

CHAPTER 1: THEORETICAL FRAMEWORK AND CAGE CULTURE CONCEPTS

1.1 Historical and global overview of fish cage culture

Fish cage culture practices dates back to the late 1800 in Southeast Asia in freshwater lakes and rivers [16] Cage culture technology took a significant development at commercial scale industry since 1960s in major Asian countries and in Europe and Americas [3] Cage culture technology was also introduced in some African countries in 1970s but it is still in its infancy [12] The rapid development and financial success of cage farming systems known in Europe, Americas and Asia was driven by a combination

of factors [10], such as available resources (including water, land, labor, energy), well established hatcheries respecting breeding techniques that produce good quality and sufficient quantity of various marine and freshwater fish seed, availability of supporting infrastructures such as feed manufacturers, fish processors by using easy and cost effective technology, applied research and development initiatives and supports from institutions, governments and universities and the private sector ensuring refinement and improvement of culture techniques, increased corporate investment and supporting government regulatory environment

Currently many fish species have been cultivated in various designs and sizes of cages in Asia, Europe and in other parts of the world In 2005, FAO reported an estimated of 40

fish families cultured in cages of which only five families (Salmonidae, Sparidae,

Carangidae, Pangasiidae and Cichlidae) make up 90 percent of the total production and

one family (Salmonidae) is responsible for 66 percent of the total production Also 80

different species are reported to be presently cultured in cage, only one species of those

Salmo salar accounts 51 percent of all total cage production while Oreochromis niloticus

accounts only 4 percent [7] and [8] Salmonids (cold water fish species) are commonly cultured in Europe and Americas while Tilapia and Carps are predominated fish species cultured in cage in Asia and sub-Saharan African countries

FAO declared a lack of statistical information concerning a global production of cultured species within cage systems and concerning the overall growth of the sector The recent data published by FAO (2007) were provided only by 62 countries worldwide and are relevant for the year 2005 The total cage aquaculture production reported was amounted

to 2,412,167 tons [8] From the reported data in 2005, FAO ranked the top 10 major cage culture producers excluding Chine which always comes at the top; After Chine (991,555 tons), Norway was ranked at the top with 652,306 tons of total production, respectively followed by Chile (588,060 tons), Japan (272,821 tons), UK (135,253 tons), Viet Nam (126,000 tons), Canada (98,441 tons), Turkey (78,924 tons), Greece (76,577 tons), Indonesia (67,672 tons) and Philippines (66,249 tons)

In Sub-Saharan African region, the countries which provided statistical data on cage culture to FAO are Benin, Gabon, Ghana, Mauritius, Mayotte (France), Mozambique, Réunion (France), Zambia, and Zimbabwe While Rwanda together with Côte d’Ivoire, Kenya, Madagascar, Nigeria, South Africa and Uganda were classified in a group of countries that are known to be actively engaged in commercial cage aquaculture [12]

In most of East African Countries, aquaculture is still at premature state In Uganda and Kenya the sector is more advanced, whereas in Rwanda and Burundi is less developed Small scale aquaculture is a dominated system with extensive production of Tilapia and/or African catfish in earthen ponds [27]

In all East African countries, the needed infrastructures for aquaculture development are not existed or not sufficient such as hatcheries and fish feed factories and markets IFOM (2013) reported a declining of wild stocks in inland lakes and river systems as well as of the marine sources in five East African Countries (Burundi, Kenya, Tanzania, Rwanda and Uganda) caused by unsustainable exploitation Also due to growing population, the per capita fish consumption is extremely low in particular in Rwanda and Burundi

1.2 Advantages and disadvantages of cage culture

The advantages and disadvantages of cage culture are adjudged by its comparative performance with other land based culture systems in terms of level of technology required for construction, ease of management, adaptability, quality of the fish reared, resource use, social implications, and economic performances

Like other aquaculture systems, cage culture has many advantages and disadvantages [35] and [10]

1.2.2 Disadvantages

Pond fish can make use of naturally occurring food, while cage grown fish only have a limited access on natural food since they cannot forage on their own Cage grown fish therefore needs to be fed by the farmer to a much higher extent The food that is given to the cage grown fish also has to be nutritionally complete, e.g contain proper amounts of all necessary vitamins and minerals

Many farmers want to optimize the stocking density when fish are grown in cages instead

of ponds A high stocking density creates a stressful environment for the fish and damages the immune system The risk of disease is therefore high The risks will be increased further if the farmer fails to provide the fish with optimal water conditions and

a satisfactory diet Cage culture can introduce or disrupt disease and parasite cycles, change the aquatic flora and fauna and alter the behaviour and distribution of local fauna

If proper water exchange is not there, the uneaten feed and metabolic waste released from cages will lead to eutrophication of the site

Barnacles can be attracted to the cages and for that additional protection has to be provided such as predator nets Poaching is easy because fish are confined in a small area Marine cages face problems like fouling and storms can damage the cages; therefore more expensive

When cages are installed indiscriminately, its impact on environment and biodiversity is adverse and it will influence on current flow and increase local sedimentation Since cages occupy open water sources, it may affect navigation in the area, or reduce landscape value of that area and are vulnerable to pollution from any source

1.3 Tilapia; Cage cultured species of choice

Tilapia, especially Nile tilapia (Oreochromis niloticus), better known as aquatic-chicken,

has become the second most important fish species in world aquaculture after carps overtaking salmonids [9] Tilapia, although native to Africa, have been introduced around the globe and its farming is growing rapidly especially in most Asian countries because

of their fast growth, ease of breeding and accept a wide range of feeds including planktons from natural sources, high disease-resistance and tolerance to poor water quality and low dissolved oxygen levels [34, 37]

Tilapias are a good source of protein and a popular target for both subsistence and commercial aquaculture in Rwanda Although tilapia as the most preferred species in Rwandan culture, it has been cultured since 1940s fostered by Belgian colonial administration and is considered almost like a native species It was raised in inland ponds and lakes Two main fingerlings production centres were constructed during this period; at Ecole des Assistants Agricole Butare (now known as Rwasave Fish Station) in

1952 and Kigembe Fish Station in 1954 [32]

The introduction of good brood from lake Albert in Uganda by Inland Lakes Development and Management Support Project (PAIGELAC/MINAGRI) and the development of Sex Reversed Tilapia (SRT) seed production technology in Kigembe National Fish station have increased fish production in existing fish ponds and lakes Through these dynamic projects interventions also a new dimension in tilapia aquaculture

in water reservoirs and cages has been recently developed

1.4 Cage design and construction

Fish Cages are enclosures used as a rearing facility for fishes It has enclosed bottom and sides It can be made of wood, net screens or wire mesh Sizes can range from one to thousand square meters Cages have an enormous diversity of designs and classifications [2, 5, 15, 28, 31]

1.4.1 Classification of cage design and construction

Beveridge [2] described four basic types of cages: fixed, floating, submersible, and submerged

Fixed cages: Consist of a net supported by posts driven into the bottom of a lake or river;

they are comparatively inexpensive and simple to build, but their use is restricted to sheltered shallow sites with suitable substrates However, they are limited in size and shape

Floating cages: Consist of a buoyant frame or collar that support the net bag whose

shapes and sizes vary according to the purpose of the farmer Rigid materials such as GI

or PVC pipes, timber, bamboos and plastic pipes can be used as frames Flotation materials such as empty plastic drums and jars can also be utilized Floating cages are less limited than most other types of cages in terms of site requirements and can be made

in a great variety of designs, and they are the most widely used ones

Submersible cages: Rely on a frame or rigging to maintain shape Submersible cages

were designed to take advantage of prevailing environmental conditions During bad weather, the cages are submerged to avoid destruction by strong waves

Submerged cages: these enclosures are underwater the whole duration of the culture

period Submerged cages allow the use of site exposed to strong winds Fewer materials are needed for framing and flotation and may yield better per cubic meter However, cage size is limited and working area is absent

The submerged cages can be wooden boxes with gaps between the slats to facilitate water flow and are anchored to the substrate by stones or posts They are used in flowing waters, while net bag designs are used in lakes [2]

Another classification system was proposed by Huguenin [31] considering technical characteristics summarized in table 1.1

Table 1.1: Classification of cage design and construction based on technical characteristics

Way of operating Surface

Submerged Place of operating Marine

Estuarine Freshwater

Means of support Fixed to bottom (usually via pilings)

Floating (buoyancy) Type of structure Rigid (usually structure and mesh)

Flexible (usually mesh only)

Access for servicing Cat walked

No catwalks (usually boat/barge serviced) Operating parameters; Biomass loading/

Feeding practices

Intensive Extensive Fed (Hand/Auto) Unfed

Environmental severity Sheltered

Exposed Open water

Source: Modified from Huguenin [31]

Loverich and Gace [15], on the other hand, classified the cages into four classes according to the effects of the currents and waves as follows:

Gravity cages: rely on buoyancy and weight to hold the shape of the cage and volume

against externally applied forces

Anchor tensioned cages: rely on anchor tension to hold their shape

Self-tensioned and supporting cages: the self-tensioning structure resists net

deformations

Rigid cages: self-supporting structures made of jointed beams and trusses

1.4.2 Components of cage design and construction

The different classes of cages described above can be built in several types and sizes; however most of them present common components [29, 31, 38]: floating system, mooring system, anchor system, net cage and services system (Figure 1.1)

Figure 1.1: Principal components of floating cage described by Vázques [28]

The design of the cage is directly related to the chosen site, inshore or offshore In this respect, as stated by Loverich and Gace [15] in their analysis of currents and waves effects on several classes of cages for offshore, the most suitable cage is a self-supporting cage

In all the cases: inshore, offshore, sheltered or not, the cage structures must withstand the forces of the currents, waves and winds, while holding stock securely This is the engineering task [28]

1.4.3 Site selection and carrying capacity of cage culture

Historically, site selection has been based largely on available space and constraints to productivity (e.g circulation or food availability) Foremost, the success of any aquaculture endeavor is the selection of best site [1, 13, 14, 18] The common practical considerations in site selection for cage farming are the following:

Shelter: A suitable area should be protected from strong winds and waves Sheltered

sites are preferred for cage culture

Water currents: Stagnant waters are used for cage farming However, sites with

sufficient currents can offer good water exchange for replenishment of oxygen and removal of waste metabolites However, excessive currents may lessen the volume of the cage, add weight to the supporting structures and moorings and may contribute to feed losses

Water Quality: The site must be free or far from sources of industrial, agricultural and

domestic pollution Water runoff from rivers will cause high turbidity, abrupt salinity fluctuations and possible destruction of cages caused by run-off debris Turbidity brought

by water run-off can affect 2 to 15 kilometer radius of a coastal area from the mouth of the river and may last for 3 to 6 days High turbidity may disrupt feeding of fish and clog

or irritate the gills which can lead to bacterial infection

Water depth: Water depth should be 2 to 3 meters for freshwater In marine

environment, deeper sites are preferred for sufficient water circulation and acceptable water quality In addition, sea cages have deeper net bags

Services and Security: Sufficient land area must be available for office, tool and feed

storage and labor / security house Availability of road, electricity or telephone should also be considered Proximity to market and production supplies may affect production costs Cage operation should be located where they can be readily observed Conflict with traditional fishing activities should also be considered

However, after FAO recommendations in order to ensure sustainable development, carrying capacity and site selection is no longer viewed in such a limited way It requires

an analysis of tradeoffs among production, ecology, governance, and social aspects [36] Site selection and carrying capacity are among the most important issues for the success

of aquaculture, and they need to be carried out in accordance with sustainability, resilience and best practice guidelines Carrying capacity appropriate for different types

of aquaculture as discussed and agreed in FAO workshop (2013) is based upon four categories; physical, production, ecological and social [14]

Physical carrying capacity is based on the suitability for development of a given activity,

taking into account the physical factors of the environment and the farming system In its simplest form, it determines development potential in any location, but is not normally designed to evaluate that against regulations or limitations of any kind In this context, this can also be considered as identification of sites or potential aquaculture zones from which a subsequent more specific site selection can be made for actual development This capacity considers the entire water body, or water bodies, and identifies the total area suitable for aquaculture

Inglis [13] and McKindsey [18] noted that physical carrying capacity does not indicate at what density cultured organisms are stocked or their production biomass Physical carrying capacity is useful to quantify potential adequate and available areas for aquaculture in the ecosystem, but it offers little information on aquaculture’s limits at the water body or watershed level within the Ecosystem Approach to Aquaculture

Production carrying capacity estimates the maximum aquaculture production and is

typically considered at the farm scale For the culture of bivalves, this is the stocking density at which harvests are maximized However, production biomass calculated at production carrying capacity could be restricted to smaller areas within a water basin so that the total production biomass of the water basin does not exceed that of the ecological carrying capacity, for example, fish cage culture in a lake Estimates of this capacity are dependent upon the technology, production system and the investment required

Ecological carrying capacity is defined as the magnitude of aquaculture production that

can be supported without leading to significant changes to ecological processes, services, species, populations or communities in the environment Fish cage culture, for example, uses ecosystem services for the degradation of organic matter and nutrients and provision

of oxygen, but a certain level of fish biomass may exceed the system capacity to process nutrients and provide oxygen, thus generating eutrophication

Social carrying capacity has been defined as the amount of aquaculture that can be

developed without adverse social impacts Angel and Freeman [1] refer to social carrying capacity as the concept reflecting the trade-offs among all stakeholders using common property resources and as the most difficult to quantify, but as the most critical from the management perspective For example, if there is widespread opposition to aquaculture in

a particular place, the prospects for its expansion will be limited

According to Little et al [14] aquaculture has the potential to exert significant social and economic impacts through upstream and downstream links around the use of water, seed, feed, chemicals, wastes expelled, etc This incorporates a broad section of people as stakeholders Similarly, employment along the value chains, both upstream and downstream, brings benefits to many people not directly involved in farming Such implications can make the setting of boundaries for the estimation of social carrying capacity very challenging

The need for sites with appropriate environmental characteristics and good water quality, the social aspects of interactions with other human activities, or conflicts over the use and appropriation of resources inland and along coastal zones are constraints to be considered

in the monitoring of existing aquaculture facilities and in the decisions to set up new facilities

1.4.4 Classification of cage culture according to different management systems

Cage culture like other culture systems is also classified as extensive, semi- intensive and intensive based on different management practices applied such as feed inputs, stocking density, etc [2]

Extensive cage culture

Extensive cage culture is restricted to freshwater such as highly productive lakes and reservoirs The system depends solely on primary production and may be limited to few species, such as tilapia, big head carp, common carp and milkfish Stocking density maybe limited in this system Extensive cage culture is practiced in highly eutrophic lakes

Semi - intensive cage culture

In addition to the primary productivity of the body of water where the cage is located, artificial food such as rice bran and commercial feeds are given the fish Semi - intensive cage culture is widely practiced in tropical freshwaters Species that feed low in the food chain such as tilapia, milkfish and big head carp are cultured To a limited extent of culturing siganids, semi - intensive system is not practiced in marine environment

Intensive cage culture

Intensive cage culture is practiced in freshwater and marine environment The system depends solely on artificial balanced diet and high stocking density The constant changing and the inherent circulation of water body lessen the possibility of

eutrophication, due to waste loadings from the cages The submerged cages can be wooden boxes with gaps between the slats to facilitate water flow and are anchored to the substrate by stones or posts They are used in flowing waters, while net bag designs are used in lakes

1.5 Management practices of fish cage culture

Cage culture management practices are aimed to increase the profitability by minimizing stock losses, promoting good growth while controlling costs

1.5.1 Fish seed and stocking practices

The source of fish seed maybe either land based hatcheries or from the wild The readily available post fry are brought from hatcheries or nurseries, and then are grown in nursery ponds or hapas from 1 to 2 months until attained desired size for stocking The post fingerlings are graded in order to stock uniformed size in cage

The smallest fingerling size recommended to stock is 15g; a fish of 15g is retained by a

13 mm bar of mesh size Larger fish can be also stocked into cages but the minimum recommended stocking density for common carps, Tilapia and catfish is 80 fish /m3 A recommended maximum stock density for beginning farmers is the collective biomass of

150 kg/m3 when fish reached harvesting size [22] The total number of fish to stock per cage can be calculated on the basis of the total weight of fish at harvest divided by the desired average weight of fish at harvest time

The total weight of fish that can be cultured is limited by the carrying capacity of the water body High stocking density of reached carrying capacity will result in increased fish stress, disease and mortality, and reduced feed conversion efficiency, growth rate and profit [22, 24, 35]

Generally, 1000 m2 surface of water body is needed to support 400 kg of fish; then the maximum number of fish that can be stocked per cage to assure the weight required by the carrying capacity of water body can be determined by simple mathematics [22]

The maximum volume of cages (in cubic meter) is also estimated by using the formula below:

Maximum volume of cage (m3) = 2.6a ; where “a” is the total surface area of water body (1000 m2) and the constant 2.6 derived from 400 kg:1000/150kg:m3

Prior to transport, post fingerlings are pre-conditioned in hapas or in tank with sufficient aeration and water flow for 1 to 2 days [21] During this period, fish are deprived of food

to empty their digestive tracts This will minimize fouling of organic matters in transport system and oxygen consumption Fish are packed and transported in the early morning when travel can be more comfortable to the fish

For transport, water tanks with continuous aeration and plastic bags one third filled of water and remaining space with oxygen are popular in transport system of Tilapia If fish are transported for considerable distance, transportation at night is recommended and water in tank and air in plastic bags or transport containers are changed every 6 hours

Fish should not be stressed during capturing, handling, counting, transport and stocking

to assure that fish are stocked healthy The survival rate of stocked fingerling may be influenced by many other natural factors such as water temperature; the survival rate of Tilapia is high when they are stocked at 20 to 22oC The survival rate can achieve 100%

in a well place cages and well managed cages; unless high mortality occurred, no adjustment needed to compensate stocking density [23]

Prior to stocking, salinity and temperature of fish being transported should approximate that on the new environment Stocking is done early morning or late evening when temperature is low Stocking management can be done two ways: fish are stocked according to a desired density which will allow fish to grow up to harvestable size or fish

can be stocked at higher density which will be redistributed to other cages as they grow [21]

1.5.2 Feeds and Feeding

After proper stocking, the most important aspect of cage culture is providing good quality feed in the correct amount to the caged fish Non-filter feeding fish confined in cage are limited access to natural food of the water body and need a nutritionally balanced diet, containing vitamins and minerals Protein content should be 32 to 36 percent for 1 to 25 gram Tilapia fingerlings and 28 to 32 percent for larger Tilapia [4, 17, 19]

Simple feeding tools may be manufactured to make feeding cages easier and to minimize feed waste For manual feeding, floating ring is used to retain feed inside the cage, feeding tray may be built inside the cage or fixed on the cage floor to retain sinking pellets and an demand feeder may be installed on the top of cage with a vertical rod inside the water that will be checked by the fish to open the feeder and allow pellets dropping in the water through the bottom hole The pellets must be purchased from reputable and established commercial feed manufacturers Farmers may also produce their own on farm made feed by mixing various agricultural byproducts

Fish are fed 3 to 4 hours after transfer when they have recovered According to McGinty and Rakocy [17] tilapia are fed a ratio varied along the reared period from 1.5 to 11% of the body weight, daily given in 2 to 5 times a day and re-adjustable daily, weekly or every two weeks based on fish growth or according to weather or environmental conditions (table 1.2) Juvenile fish are fed higher protein diet at greater frequency than adult fish For juvenile and adult fish, sinking or floating feeds can be used Floating feed allow observation of the stocks Sinking feed are preferred for sites with strong winds, waves and current Feeding rate tables or programs are required to make periodic increments in the daily ration [33]

The fish should be sampled every 4 to 6 weeks to determine their average weight and the correct feeding rate for calculating adjustments in the daily rations Adjustment can be made between sampling periods by estimating fish growth based on an assumed feed conversion ratio (feed weight divided by the weight gained) For example, with a feed conversion ratio of 1.5, a fish should gain 10g for every 15g of feed consumed

The correct feeding rate, expressed as the percentage of body weight, is multiplied by the estimated weight to determine the daily ration The recommended feeding rates are listed

in the following table modified from McGinty and Rakocy [17]

Table 1.2: Recommended daily feeding rates, expressed as the percentage of body weight, for Tilapia of different sizes

Fish weight

(g)

Feeding rate (%)

Fish weight (g)

Feeding rate (%)

Source: Modified by author from McGinty and Rakocy [17]

Feeding rate tables serve as guides for estimating optimum daily ration, but are not always accurate under a wide range of conditions, such as fluctuating temperature or dissolved oxygen The demand feeder are recommended to eliminate the work of feed weighing, fish sampling, calculations and uncertainty of feeding rate schedules by letting the fish feed themselves

1.5.3 Stock sampling

To remove fish during sampling, the cage is partially lifted out the water, and fish are captured with a dip net A sample of fish taken may then be counted, weighed and returned to the cage for further growth or all of the fish maybe harvested Fish can be graded when the sizes vary significantly during the culture period

1.5.4 Harvesting

Before harvesting, prepare all materials and equipments required Two or three persons can harvest one cage Harvesting of cultured fish in cage is done easily, small cages are brought close to shore and fish are scooped Harvested fish are graded, counted and weighed If fish size uniformity is more important, 4 weeks or more maybe required for complete harvest, because not all fish reach the desired harvest size at the same time

Proper handling and post-harvest processing of Tilapia is very important for the fishing industry and for the consumers The quality of fish depends on how it handled from the time it is taken out from the water until it reaches the kitchen Three key rules in handling fresh fish must be taken into consideration; cleanliness, care and cooling as defined by

Cleanliness: observe cleanliness throughout the fish handling chain

Care: the harvested fish are food treat them as such Work on fish as quickly and as

promptly as possible, sort fish properly before packing, don’t throw, trample or kick the fish, drain fish before icing

Cooling: Temperature is the most important single factor affecting the quality of fish

Use plenty ice; put additional layer of ice on top, bottom and side of fish in boxes or shelves Lay the fish belly downward to prevent the entry of dirty water into the fish cavity

Fresh fish transported to far distance must be packed with ice to ensure their freshness when reach to consumers Proper packing fresh fish with ice means, arranging the fish and ice alternatively in the container, to maintain 5oC chilling temperature which is attained with the ratio of 1 kg of ice to 2 kg of fish [39] Fresh fish may be transported in styrofoam boxes, conical tubes baskets and plastic containers The more sophisticated transport method is refrigerated trucks When transporting fresh Tilapia within the local markets, wholesalers should pack them in ice Even upon reaching their destination, fish should be repacked with ice and sold to retailers and eventually to consumers

1.5.5 Cage maintenance and monitoring

Care and maintenance of cages are daily or routine work Growth of bio-fouling organisms in net bags is primary problem of cage management In fresh water cages, excessive growth of algae, sponges and debris on nets may impair water circulation in the culture system and can affect the health and growth of the fish

Nets should be regularly cleaned by brushing off the algae or changed when needed Checking the net screen should be done every day for wear and tear as there might be possible damage that may lead to escape of fish stock and diving regularly to inspect the conditions of nets and others materials submerged in the water

1.5.6 Record keeping

Consistent and accurate record keeping is more indispensable to determine the productivity and profitability of cage fish culture operation Good record keeping habits will help the producers to be involved and acquainted with not only costs of production and market prices and their patterns, but also with fish behavior, growth and their interactions with the environment

Fish are sensitive to their environment, so fatal conditions can occurs abruptly and spread rapidly Good record keeping will help the managers to be able to anticipate and quickly detect any problem on a daily basis

A sheet or book for record keeping should contain the space in which cage operator will record a daily track of both important economic and environment data related to the cage fish culture operation Each producer should have record keeping sheets appropriate for the cage culture operations

1.6 Cage culture economics

Potentials cage operators must invest enough time and effort to determine as accurately

as possible the cost and return of their operations Analysis of the pre-estimated figures will give a reasonable prediction whether the venture into cage fish culture will be a profitable one Once the venture is underway, the estimated figures will be replaced by the actual ones to reveal the true economic picture of the venture Costs and returns figures should be updated whenever new information is available to keep abreast for the financial situation

Many examples of enterprise budgets have been developed by economists to provide simple methods to organize and analyze production costs and returns Actual costs, returns and production factors are different for every operation system and probably for every production cycle So accurate record keeping help the producer to determine the actual figures The following economic parameters are the data and calculations contained in the example enterprise budgets as defined by different economists [25, 26, 39]

1.6.1 Production costs

These are a group of numbers or assumption upon which the budget is based For financial profitability analysis, producers have to determine such things as how many fish can be grown in their cages, how fast the fish will grow and which amount of feed the fish will eat Most of these production factors are placed up front in the budget tables, while others (fish dead or lost, feed conversion ratio, etc) are contained in the calculations

A few of assumptions are indirectly given such as all the fish will be grown in one batch and harvested at the same time, the fish will be sold live and death loss will occur after the fish have been fed out to market weight

The production factors are often the most difficult for producer to determine accurately, but are very important in analyzing profitability

Variable costs

These are the costs of resources which quantity varies during the production period based

on the level of production and the quantity produced Cage maintenances, fingerlings, feed, product containers, etc are the items considered as variable in the budgets

Fixed costs

These are the costs which are independent of the production level, and have to be paid whether or not production occurs in particular year An expenditure on a resource whose quantity is not varied during the production period is a fixed cost Examples include cages, aerators, hauling tanks, etc Generally, fixed costs are spread out over the expected life of the production input involved This allows the producer to take into account the long-term view of profitability

First year investments plus variable costs

This figure shows the amount that the producer must come up with before the first year of production to buy all necessary equipment and to pay all first year’s operating expenses

1.6.2 Returns

Three different returns are calculated in the budgets Each provides different and useful information to the producer Gross return indicates how much cash will be generated as a result of fish sales Gross return less variable costs reveals how much money will be left over after paying the variable costs This money is then available to pay for fixed

production costs and a return to the producer’s labor and management If this figure is negative, production should not be undertaken In the short run, one or two years, production should occur if all variable costs are covered However, for long-term success, fixed costs as well as variable costs must be covered

1.6.3 Break-even price

This is the figure to look at when deciding whether or not to undertake the cage fish culture venture If the expected market price is equal or above to the break-even price, then the producer will respectively break even or make a profit on the venture

1.6.4 Market identification

Markets identification is a critical aspect of any successful aquaculture venture Because there is no established marketing system for cultured fish in most of the states, cage culturists have to spend considerable time and effort in developing marketing system for their production Marketing plan should be developed before production is even begun

In market identification, the producers must find the answers for some of the questions such as; what is the specific market to sell the fish? What fish species is accepted or more preferred at the available market? What is the selling price for fish in this market? What are the form, size, volume, and frequency requirements for this market? Can I meet these requirements?

Producing a small number of fish limits the range of possible markets, but prospects the chance for obtaining a good selling price that is enough to cover production costs and still capitulate a profit that is quite good

Possible markets for cultured fish that should be targeted by the producers are live haulers, processors, distributors, hotels, restaurants, grocery or specialty stores of retailers, direct to consumers [26]

CHAPTER 2: STUDY DESIGN AND METHODOLOGY

Figure 2.1: Schematic diagram of the contents

Management practices applied

Appreciation

of current productivity

Constraints

of current cage culture

Current situation

Tilapia cage culture in Rwanda

Prospects for future development

Solutions for future development

Sustainable way for further expansion of tilapia cage industry in Rwanda

Figure 2.2: Schematic diagram of the study design and methodology

Collection of secondary

data and information

Survey (Formal questionnaires)

Field visits (Personnal

observations)

Collection of primary data

Total enumeration of cage operators from

all sites (List of total population)

Information and data encoding and entry

in Excel and SPSS software

Data analysis

Results and discussions

Conclusion and recommendations

2.1 Scope and duration of the study

To schedule a frame of survey and interviews, a list of all cage operators practicing Tilapia cage culture in Rwanda was prepared and grouped according to their cage farms location such as in lakes or water reservoirs and districts bounded the lakes (appendix 2)

Because of their limited number a complete enumeration was done during the field visits and 52 tilapia cage producers operating in Rwanda were identified and surveyed for the present study Both survey and interviews were scheduled from January to April 2014 The two last months of this study, from May to June 2014 were concentrated on desk-works for data entry and analysis

2.2 Survey

Primary data from the cage operators was obtained through a structured questionnaire (Appendix 1) which was personally administered through interview with respondents The targeted respondent was firstly a technician/person in charge of dairy cage operations, either for his absence or for the case he is not able to give the answer, the cage owner was also interviewed Both close-ended and open-ended questions were asked to 52 tilapia cage operators (total population) Due to a small number of the population, no sampling method used for this study; thus all tilapia cage operators in Rwanda were surveyed Qualitative and quantitative data collected from surveyed respondents included the information on:

 the socio economic of tilapia cage operators such as age, organization, education level, experience in cage culture, reason for adoption of cage culture, etc

 the management practices, production parameters, inputs, outputs and profitability

of tilapia cage culture, and

 the major constraints encountered and solutions suggested for future development

of tilapia cage culture