Cage fish farming in Lake Victoria, Tanzania

World Maritime University World Maritime University

The Maritime Commons: Digital Repository of the World Maritime The Maritime Commons: Digital Repository of the World Maritime

University University

World Maritime University Dissertations Dissertations

10-31-2021

Cage fish farming in Lake Victoria, Tanzania: a recently rising food Cage fish farming in Lake Victoria, Tanzania: a recently rising food

production area and its effects on the environment and production area and its effects on the environment and

community. community.

Kwilasa Lushanga Ng'Wigulu

Follow this and additional works at: https://commons.wmu.se/all_dissertations

Part of the Aquaculture and Fisheries Commons

Recommended Citation Recommended Citation Ng'Wigulu, Kwilasa Lushanga, "Cage fish farming in Lake Victoria, Tanzania: a recently rising food production area and its effects on the environment and community." (2021). World Maritime University Dissertations. 1724. https://commons.wmu.se/all_dissertations/1724

This Dissertation is brought to you courtesy of Maritime Commons. Open Access items may be downloaded for non-commercial, fair use academic purposes. No items may be hosted on another server or web site without express written permission from the World Maritime University. For more information, please contact [email protected].

WORLD MARITIME UNIVERSITY

Malmö, Sweden

CAGE FISH FARMING IN LAKE VICTORIA, TANZANIA: A RECENTLY RISING FOOD

PRODUCTION AREA AND ITS EFFECTS ON THE ENVIRONMENT AND COMMUNITY.

By

KWILASA LUSHANGA NG’WIGULU

Tanzania

A dissertation submitted to the World Maritime University in partial fulfillment of the

requirements for the reward of

MASTERS OF SCIENCE

in

MARITIME AFFAIRS

(OCEAN SUSTAINABILITY, GOVERNANCE AND MANAGEMENT)

2021

Copyright Kwilasa Lushanga Ng’wigulu, 2021

i

Declaration

I, KWILASA LUSHANGA NG’WIGULU, a student of the World Maritime University (WMU) in the

Masters of Science in Maritime Affairs, specialized in Ocean Sustainability, Governance and

Management hereby declare to the Curriculum Assessment Committee (CAC) of the World

Maritime University that, this is my own document and have never been presented or submitted

for award of the same or different Degrees in this University or any other Universities in the World.

Signature

Date: 21 September 2021

Supervised by: Professor Francis Neat

World Maritime University, 21 September 2021

ii

Acknowledgement

Acknowledgements and thanks are due for the protection and assistance from the Almighty God

for keeping me healthy during the period of 14-months of my studies. My great gratitude goes to

my supervisor Professor Francis Neat for his good and productive guidance in the course of

execution of this task.

Finally, deserving my thanks is to WMU Management for their truthful cooperation and for the

fulfilment of my studies.

iii

Abstract

Title of Dissertation: Cage fish farming in Lake Victoria, Tanzania: A recently food

production and its effects on the environment and community.

Degree: Master of Science

Cage fish farming is a type of aquaculture practice that is expected to be increasingly important

in the future to fill up the gap for the dwindling fish capture in Lake Victoria, Tanzania. It is a high-

yielding type of aquaculture with important social and economic benefits such as the creation of

jobs, food security, income generation, and improvement of infrastructures for the communities

along the Lake. Cage farming is still an innovation for most developing countries including

Tanzania, whereby Clarias gariepinus (African catfish) and Oreochromis niloticus (Nile tilapia) are

only fish species largely farmed. Factors like markets, simple entry to free water bodies and

material use flexibility are some of factors, which drove the spread of cage fish farming in African

countries. The negative impacts of cage fish farming have been well documented worldwide,

however, in Lake Victoria the practice started in 2005. Thus, in Lake Victoria, Tanzania, there is

little or no available experience-based assessment to show the negative environmental impacts.

A comprehensive and systematic approach that involved both an exhaustive systematic literature

review and extensive desk reviews of documents was used to build a basis to understand and

provide historical data for identifying cage culture as an acceptable fish farming practice, or a

supplement system to dwindling fish capture in Lake Victoria. Both environmental and

socioeconomic impacts of the cage fish farming system are evaluated. Currently, cage fish

farming practices in the Lake Victoria environment have minimal negative impacts, however, due

to the expected expansion of cage farms in the lake, the impacts on the water quality and

biodiversity can also increase. Management measures for sustainable aquaculture and

investments in the lake are discussed to guide the investors. The effectiveness of the regulatory

and environmental framework determinants that management authorities and investors should

consider were evaluated and found to be adequate for current low levels of cage farm production.

The findings of this study can help to guide sustainable investments and cage fish farming

development in Lake Victoria.

Key words: Aquaculture; Cage fish farming; Environmental impacts; Lake Victoria;

Socioeconomic impacts; Water quality

iv

Table of Contents

Declaration i

Acknowledgement ii

Abstract iii

Table of Contents iv

List of Tables vi

List of Figures vii

List of Abbreviations viii

1. Introduction 1

1.1 Background 1

1.2 Cage Fish Farming 3

1.3 Cage fish farming in Africa 3

1.4 Aquaculture in Tanzania 4

1.5 Fishery in Lake Victoria 6

1.6 Cage fish farming in Lake Victoria 7

1.7 Environmental Impacts of aquaculture 7

1.8 Legal, Regulatory and Institutional Framework for Aquaculture in Tanzania 8

1.9 Problem Statement 10

1.10 Aims and objectives 10

1.11 Research questions 10

1.12 The rationale of the Study 11

1.13 The structure of the study 11

2. Materials and methods 12

2.1 Description of Study area 12

2.1.1 Lake Victoria .............................................................................................................12

2.1.2 Mwanza Gulf area of Lake Victoria ...........................................................................13

2.2 Research Methodology 14

v

2.2.1 Sources of data and treatment .................................................................................14

2.2.2 Literature review methods ........................................................................................14

2.2.3 Data analysis ............................................................................................................14

3. Literature review 15

3.1 Environmental impacts of cage fish farming 15

3.1.1 Nutrients loading in water environments ...................................................................15

3.1.2 Water quality changes associated with cage farming ................................................17

3.1.3 Fish cages, non-native species, diseases and parasites occurrence ........................19

3.1.4 Impacts of cage fish farming on biodiversity .............................................................23

3.2 Cage culture across Africa 26

3.3 Socio-economic impacts of cage fish farming 27

3.4 Aquaculture Policy analysis 30

4.0 Discussion 35

4.1 Environmental impacts of cage fish farming in Lake Victoria 35

4.1.1 Impacts of nutrient loading in water environments ....................................................35

4.1.2 Water quality changes associated with cage farming ................................................36

4.1.3 Fish cages, non-native species, diseases and parasites occurrence ........................36

4.1.4 Impacts of cage fish farming on biodiversity .............................................................37

4.2 Cage fish farming and the community 38

4.3 Compliance status of cage fish farmers on aquaculture regulations 38

5.0 Conclusion and recommendations 40

References 42

Appendices 49

vi

List of Tables

Table 1. Nutrient release from cage fish farms into the environment 16

Table 2 Water quality status in Lake Victoria Tanzania 18

Table 3: Water quality status in Lake Victoria, Kenya 18

Table 4. Water quality parameters at Nile Fish Farm, Lake Victoria, Uganda 19

Table 5. Parasites in cage fish farms in Lake Victoria, Kenya 21

Table 6. Viral diseases in caged and wild fishes in Lake Victoria 22

Table 7. Increased macroinvertebrate community in the cage fish farms environment 25

Table 8 Summary of cage Farms 27

Table 9 Characterized socio-economic benefits of cage farming in Lake Victoria 28

Table 10 Socio-economic impacts of cage fish farming 29

Table 11 Legal provisions for aquaculture management in Tanzania 31

vii

List of Figures

Figure 1. The global aquaculture production capacity 2

Figure 2. The global fish consumption and utilization 2

Figure 3: Aquaculture development in Tanzania 6

Figure 4: Procedural guidelines for establishing aquaculture projects in Tanzania 9

Figure 5. Physical area of Lake Victoria 12

Figure 6: Surveyed area for cage fish farming in the Mwanza Gulf of Lake Victoria, Tanzania 13

Figure 7: The health status of cage fish farms in Lake Victoria, Kenya 20

viii

List of Abbreviations

BOD Biological Oxygen Demand

DO Dissolved Oxygen

EIA Environmental Impact Assessment

EMA Environmental Management Act

FAO Food and Agriculture Organization

GDP Gross Domestic Product

NBS National Bureau of Statistics

NEMA National Environmental Management Authority

NEMC National Environment Management Council

pH Hydrogen ions concentration

SDG Sustainable Development Goal

TAFIRI Tanzania Fisheries Research Institute

URT United Republic of Tanzania

1

1. Introduction

1.1 Background

Globally, aquaculture continues to extend its production capacity to about 114.5 million tonnes in

2018 with an estimated value of USD 401 billion (Figure 1, FAO, 2020). The global fish production

is projected to rise to 204 million tonnes by 2030 (FAO 2020) contributing to food security,

employment, and income (FAO, 2020; Garlock et al., 2020). Total aquaculture products comprise

a diversified assembly of flora and fauna types (328 types revealed in the year 2017), varying

from producing unicellular Chlorella algae in ponds to Atlantic salmon in cages (Tacon, 2020;

Tacon & Halwart, 2007). In 2018, a large percentage (more than 35 per cent) of global aquaculture

products came from Asia (FAO, 2020), whereas developing nations produce about 6 percent each

year (Garlock et al., 2020; Tacon, 2020). There is increased growth and consumption of

aquaculture products worldwide (Figure 2), whereby the developing countries have increased

their consumption from 5200 tons in 1961 to 18800 tons in 2013 (Orina et al., 2021).

Sustainable fish production as one of the fundamental goals for sustainable development

incorporated in the 2030 agenda (Orina et al., 2018), requires international collaboration for

positive results of the SDG 14 (FAO, 2020). Fish farming is projected to extend more in order to

satisfy the future global nutritional needs (Bostock et al., 2010). This will offer resilience, enhance

the wellbeing of local communities, food supply, job opportunities, and reduce poverty. In 2018,

about 59 million people had been engaging in fisheries and aquaculture of which only 3.9 million

fish farmers came from Africa (FAO, 2020).

Fish farming is the quickest developing sector of the world food economy (Staniford, 2002)

contributing about 42 percent to 58 million tons of fish supplied globally (Challouf et al., 2017). By

region, Africa has the quickest development in the fish farming sector, however from a small stand

of about 18 percent compared to the Asian region (FAO, 2020).

2

Figure 1. The global aquaculture production capacity (Source: FAO, 2020)

Figure 2. The global fish consumption and utilization (Source: FAO, 2020)

3

1.2 Cage Fish Farming

Cage fish farming is the practice of holding fish in vessels, which are closed on their sides and

the bottom with netting materials for protecting the fishes, meanwhile allowing free movement of

water to supply oxygen to the enclosed fishes. Usually, cages are floated in rafts, and either

moored to the reservoir bottom or connected to the shore by a wooden walkway (Mbowa et al.,

2017). Thus, the cage fish farming system is technologically, socially, financially, and biologically

complicated and needs critical expertise, research and versatile learning (Gephart et al., 2020).

It is a high-yielding type of aquaculture in many nations in the world, differing in scale from

sustenance to commercial operations (Halwart & Moehl, 2006; Tacon & Halwart, 2007).

Commercialized cage fish farming started in Norway in the 1970s because of improved

technology, support from the government, marketing, and private investment. In addition, the

increased competition within the sector caused by easy access of production resources, the

economics of scale, the multiplied productiveness per unit area, and the expansion to the

utilization of cage farm sites influenced the widespread use of cage fish farming. Currently,

commercialized cage culture activities are constrained by high cost fish farming with multiple feed

fishes, such as salmon and omnivorous freshwater fish species such as Tilapia (Tacon & Halwart,

2007).

1.3 Cage fish farming in Africa

Fish farming in Africa started in the 1920s and expanded when pond fish culture trials of tilapia

were developed in Central Africa by the 1940s. Cage fish farming of tilapia has a relatively short

background in Africa compared to the pond culture system (Béné et al., 2016). Freshwater cage

fish farming in Africa is developing in response to the regional deficiency of fish production as well

as provision of work and income (Musinguzi et al., 2019; Shava & Gunhidzirai, 2017). Production

is still growing slowly (Brummett et al., 2008) representing just 2.5 percent of the global production

(Orinda et al., 2021). Cage culture remains an innovation and less developed than it could be in

the majority of African nations (Brummett et al., 2008; Halwart & Moehl, 2006; Kashindye et al.,

2015). The growth rate of aquaculture in Africa is about 2 percent (Mmanda et al., 2020), and its

share of global aquaculture products is minor (Rukanda and Sigurgeirsson, 2018) with a

compound annual growth rate of 15.55 percent of products derived from native species such as

tilapia and African catfish (Adeleke et al., 2020; Balirwa, 2007; Hecht, 2006). In 2002, aquaculture

production in the African continent was about 399,000 tonnes (1% of the global production)

(Balirwa, 2007). The specialization, market, and strains reliant are sources of fast take-up of cage

4

fish farming while its moderately ease, material use flexibility, development, and simpler entry to

free water bodies drove the spread of cage fish farming in African countries (Ameworwor et al.,

2019; Tacon & Halwart, 2007). However, resources are dedicated to better augmentation and the

production of seed is still a private-based sector (Adeleke et al., 2020; Hecht, 2006). Thus, seed,

feed, finance, skills/information, and marketing are key elements for successful cage farming in

African countries (Halwart & Moehl, 2006).

1.4 Aquaculture in Tanzania

In Tanzania, freshwater aquaculture production began in 1949 (Rukanda & Sigurgeirsson, 2018).

Regardless of the prospects and long record, its commercial production and importance to food

security is largely unrecognized. Commercial aquaculture in Tanzania is a new sector dominated

by Onchorynchus mykiss (rainbow trout), Clarius gariepinus (African catfish), Oreochromis

niloticus (Nile tilapia), Eucheuma cottonii, E. spinosum (seaweed) and Chanos chanos (milkfish)

production (Shoko et al., 2011). The industry is essentially a subsistence occupation practiced by

local communities along the coastal and inland regions contributing to people's needs for nutrition,

and it provides job opportunities and income generation (FAO, 2020). In 2014 only 20,134 ponds

and nine raceway systems were established whereas, in 2016, about 18,900 people were

engaging in fish farming in Tanzania, producing about 3,840 tonnes per year earning about

Tanzania shilling 22,000 million (Mulokozi et al., 2020). Fish marketing in Tanzania is mostly a

small-scale activity with a locally organized value chain. About 42 percent of the harvested fish

had been domestically fed on and the remaining 57 percent had been sold locally (Chenyambuga

et al., 2014; FAO, 2012). Only a few farmers are known to export farmed fish to a neighboring

country. The benefit of aquaculture to national food security and monetary improvement continues

to be negligible, and the effect on poverty relief is consequently negligible (FAO, 2012) with less

than 1% contribution to the national GDP (NBS, 2014). This has been witnessed by the decline

in freshwater aquaculture production from about 1,6000 tons in 1992 to about 1400 tons in 2008.

Currently, aquaculture products, for instance, seaweed, are transported and processed abroad at

high cost and the commodities are re-imported back to Tanzania for consumption. Hence, for

profitable farming, seaweed could be processed and consumed in Tanzania (Mulokozi et al.,

2020). Despite that freshwater aquaculture started earlier than mariculture in Tanzania, its speed

of growth is low with an estimated production of about 200 tons per hectare per year when

compared to about 3,800 tons per hectare per year of mariculture between the years 1982 and

2005 (Shoko et al., 2011). However, in the sub-saharan region, Tanzania is a country with good

aquaculture production (FAO, 2010). This contributed by the presence of both freshwater and

5

marine aquaculture of which about 1400 km of the coastal line and marine water covering about

64,000 km2 provides opportunities of both pond based and freshwater cage mariculture systems

(URT 2015). The large fish market is within the country whereby fish processing is carried out

alongside the Indian Ocean and Lake Victoria. Tilapia and Catfish species involve the freshwater

production while milkfish, prawns, crabs and seaweed from mariculture (Figure 3). (Rukanda &

Sigurgeirsson, 2018). Unlike seaweed culture, which engages approximately 20,000 farmers

(Shoko et al., 2011), freshwater aquaculture in Tanzania comprises about 19,000 farmers working

on one or more small ponds both in freshwater and marine water culturing mostly tilapia and

catfish (Mmochi, 2011; Mulokozi et al., 2020; Rukanda & Sigurgeirsson, 2018; van der Heijden,

Peter GM et al., 2018). Although Tanzania is rich in both freshwater and saltwater (64,300 km2

and 64,000 km2 respectively), low advance and obsolete innovation bring about low aquaculture

production (Mmanda et al., 2020; Rukanda and Sigurgeirsson, 2018). In recent years, the fish

farming sector in Tanzania has gained acceptance as witnessed by the booming of fish farms

from 14,000 fishponds in 2004 to 26,000 in 2019, with annual production of about 18,000 tons.

However, the number of professionals, insufficient quality seed and feed (Mmanda et al., 2020)

limits the sector. For example, presently, there are twelve operating tilapia breeding places in

Tanzania, three government-owned and nine owned by private companies which produce

fingerlings with low quality because of mixed species, lack of support from the government, and

shortage of specialists in feed formula and breeding (Kajungiro et al., 2019). Thus, putting

resources into innovations like cages is needed to improve production (Rukanda and

Sigurgeirsson, 2018), and an organized breeding plan is needed to improve food security with

minimal effects to native germline (Kajungiro et al., 2019).

6

Figure 3: Aquaculture development in Tanzania. Source: Rukanda & Sigurgeirsson, (2018)

1.5 Fishery in Lake Victoria

Fishery in Lake Victoria is mainly artisanal with a move to commercial production whereby silver

cyprinid dagaa, tilapia and Nile perch accounting for most of the catch (Nyamweya, 2017;

Luomba et al., 2016). Thus, the lake supports food supply, employment and provides income to

rural communities. The Lake supports more than 30,000,000 individuals of which about 150,000

individuals are employed in the fishery sector (Vanderkelen et al., 2018) with an annual yield of

about 1,000,000 tonnes (Sitoki et al., 2010). The introduced Nile perch contributed to the

increase in fish catches and hence changed the system to commercial fishery with export

capacity of about 90 per cent in the East African countries (Tanzania, Uganda, and Kenya). For

instance, in 2014, about USD 650 million worth believed to come from the lake. The fishery

activities in Lake Victoria contribute to national GDP, foreign exchange, revenue, jobs, and food

is 2.8% in Uganda, 2.5% in Tanzania, and 0.5% in Kenya. However, human-oriented activities

such as farming, overexploitation of natural resources have caused negative effects on the lake,

affecting its ecosystems. As a result fish capture declined, biodiversity composition changed and

the sustainability of the Lake through which the socioeconomic benefits of the local communities

depends upon it (Nyamweya et al., 2020).

7

1.6 Cage fish farming in Lake Victoria

Cage culture practices in Lake Victoria were introduced in 2005; but the expected outcomes have

not yet been achieved due to challenges that face the industry such as high initial investment

costs and inadequate supply of quality seeds and feed. Currently, the number of cages in Lake

Victoria has increased (Njiru, J. M. et al., 2019) in order to increase fish production (Kashindye et

al., 2015; Njiru, J. M. et al., 2019). This relates to levels of technological advancement, whereby

cage culture in Lake Victoria is fast gaining prominence in aquaculture production contribution

(Orinda et al., 2021). Experience shows that a permit system is required for effective monitoring

and management of cage farming. This is because of the anticipated negative impacts of cage

fishing on the environment and ownership problems associated with public water resource

allocation (Béné et al., 2016; Mbowa et al., 2017). Tanzania, like other countries in the world,

restricts cage fish farming practices in public waters including a shared Lake Victoria (Tanzania

Fisheries Act, 2003). Currently, however, Uganda and Kenya started both medium and large-

scale cage fish farming systems on Lake Victoria (Halwart et al., 2006). On the other hand,

recently, cage fish farming practices in Lake Victoria, Tanzania, have been allowed only as

experimental trials associated with a mechanism of undertaking environmental impact

assessment in order to avoid the anticipated negative environmental effects, which might be

caused by the activity (Kashindye et al., 2015; Njiru et al., 2019). These effects may include

eutrophication, poor water quality due to fecal matter and excretory, diseases and parasites

spread due to escaped fish from cages interacting with wild fishes (Sitoki et al., 2010). Thus, if

not controlled well, cage culture practices may become an environmental catastrophe. Hence,

there is a need for changing policy strategies and improving scientific research for guiding cage

farming activities (Cowx & Ogutu‐Owhayo, 2019; Njiru et al., 2019).

1.7 Environmental Impacts of aquaculture

Despite the advantages of aquaculture, namely the supply of food, the creation of employment,

and income for developing economies, aquaculture is often criticized for its environmental

consequences (Bouwmeester et al., 2021). Aquaculture may result in direct destruction of

ecosystems (Casadevall et al., 2021; Martinez-Porchas & Martinez-Cordova, 2012) such as

mangrove for aquaculture farms (e.g. tropical shrimp) and discharge of waste into the ecosystem,

which can have an effect on microbial functions and water quality (Chen et al., 2017; Martinez-

Porchas & Martinez-Cordova, 2012). Another ecological effect that can affect aquaculture itself is

associated with diseases such as salmon lice Lepeophtheirus salmonis). The translocation and

8

introduction of aquaculture stocks can result in the co‐introduction of pathogens and parasites. In

addition, aquaculture activities may cause the shift of native species as the escaped fishes from

cages interacts with wild fishes (Bouwmeester et al., 2021; Casadevall et al., 2021; Martinez-

Porchas & Martinez-Cordova, 2012). Overfeeding fish is another aspect that can influence

susceptibility to diseases and infection as well as enhancement of greenhouse emissions

because of pollutant discharge (Yogev et al., 2020). Unconsumed feed because of overfeeding

may bring about eutrophication that could cause phytoplankton blooms, loss of life of benthic

organisms, as well as unwanted smell and the presence of pathogens in the discharge sites

(Martinez-Porchas & Martinez-Cordova, 2012). Thus, for a sustainable aquaculture practice and

environmental protection, there is a need for improvement of aquaculture regulations and laws to

minimize the impacts, which may arise from aquaculture activities (Martinez-Porchas & Martinez-

Cordova, 2012).

1.8 Legal, Regulatory and Institutional Framework for Aquaculture in Tanzania

The aquaculture sector in Tanzania is vested in the national legislations, which includes The

Fisheries Act, 2003, The Fisheries Regulations, 2009, the Tanzania Fisheries Research Institute

Act, 2016, and other inter-sectoral Acts such as the Water Resource Management Act, 2009 and

the Environmental Management Act, 2004. The Director of Aquaculture Development Division

governs the day-to-day activities of aquaculture

The Fisheries Act, 2003 with its Regulations (The Fisheries Regulations, 2009) currently governs

the management and development of aquaculture. It ensures the long-term sustainable use of

aquaculture products by integrating all laws on aquaculture to permit the growth of the sector in

Tanzania. The Act streamlines the sector to respond directly to matters concerning aquaculture

development, and to comply with other rules and regulations for protecting the environment from

adverse impacts, which may arise from aquaculture activities. For instance, section 11(1) of The

Fisheries Act, 2003 that reads together with Regulation 35 of The Fisheries Regulations, 2009

requires that the Director of Aquaculture in joint effort with stakeholders to make sure that

aquaculture practices are carried out sustainably and should not should not damage the quality

of the environment. The aquaculture regulations direct the procedure to be followed when a fish

farmer intends to establish an aquaculture project. The size of the project or the farm determine

the kind of procedures (Figure 4), for instance, large scale aquaculture farmers are required to

carry out EIA study prior to establishment of the project. The EIA study foresees the impacts of

the proposed project and suggests the mitigation measures as well as the environmental

9

monitoring plan. The investor or proponent seeks advice from an environmental expert and

conducts an EIA study through NEMC, which is mandated by EMA, 2004 to review the

environmental impact statements, and recommends for approval and certification by the Minister

responsible for the environment. The EIA certificate is issued with specific conditions and

guidelines for implementation and monitoring of the project such that the project is sustainable

while protecting the environment. On the other hand, the Tanzania Fisheries Research Institute

Act, 2016 provides competences and powers concerning development and reinforcing research

on aquaculture activities. The Act mandates TAFIRI to promote, conduct, and coordinate research

in fisheries and in aquaculture in Tanzania in accordance with Section 6(1) of the Tanzania

Fisheries Research Institute Act, 2016. The Act also mandates TAFIRI to monitor and regulate

aquaculture activities aiming to develop better fish farming practices, manufacturing and

processing of fish products; as well as protecting the aquaculture sector.

Figure 4: Procedural guidelines for establishing aquaculture projects in Tanzania. Source:

Rukanda & Sigurgeirsson, (2018)

10

1.9 Problem Statement

The decrease in fish capture from Lake Victoria stimulated investment in cage aquaculture at both

sustenance and commercial levels in order to fill the gap of fish productions (Kashindye et al.,

2015; Limbu et al., 2017; Njiru, J. M. et al., 2019; Njiru et al., 2018). Aquaculture activities in

Tanzania have grown from small-scale to commercial scale investment industry (Njiru, M. et al.,

2008). Cage aquaculture, if not well managed, could cause clashes with other water uses,

destruction of the ecological system, and economic collapse to aquaculture goals (Kashindye et

al., 2015; Musinguzi et al., 2019; Ojwala et al., 2018; Njiru, M. et al., 2008; Çulha & Karaduman,

2020). The challenge, therefore, is to develop strong approaches and guidelines, both to secure

community wealth and improve strategic policies that will prevent adverse impacts for the lake

ecology. It, therefore important for this study to examine the evidence for the negative impacts of

cage fish farming in Lake Victoria and hence, fill the knowledge gap through investigation of its

environmental and socio-economic impacts.

1.10 Aims and objectives

This study seeks to assess the environmental impacts and socio-economic status related to

caged fish farming in Lake Victoria and evaluate what a sustainable future for aquaculture in this

region is. Specifically, the purposes of this study are -

1. To investigate the environmental consequences which may be caused by cage

aquaculture in Lake Victoria, Tanzania

2. To examine socio-economic changes associated with cage culture in Lake Victoria,

Tanzania; and

3. To identify ways to improve aquaculture management and reduce the environmental

impact on Lake Victoria, Tanzania

1.11 Research questions

In this study, I pose three specific research questions;

1. How does cage aquaculture affect the water quality and biodiversity of Lake Victoria?

2. How has the economic and social status of the lakeside community been affected by the

cage aquaculture practices in Lake Victoria?

3. How effective is regulation and management concerning cage aquaculture in Lake

Victoria, Tanzania?

11

1.12 The rationale of the Study

Today, Tanzania is adopting “The Blue Economy Concept'' by mainstreaming aquaculture as a

crucial venture of national economic development and as a means of employment, food security,

income generation and livelihood improvement. Thus, cage fish farming is a type of aquaculture

practice that is expected to be increasingly important to fill up the gap for the declining fish capture

in Lake Victoria, Tanzania. However, cage farming is still a new aquaculture technology in

Tanzania, whereby its negative environmental impacts, the socio economics benefits as well as

the dependence of the communities around the Lake are not well understood. The findings of this

study will therefore help aquaculture researchers, environmental managers and environmentalists

with useful experience-based assessment of cage fish farming in Lake Victoria, Tanzania. In

addition, since cage fish farming is a system in Tanzania, strategic options, particularly policy and

regulatory strategies are important for the country to properly make use of benefits from cage fish

farming as well as to address challenges, which may arise from it.

1.13 The structure of the study

Structurally, the study consists of five parts. Part 1 provides the introduction of the study, which

comprises the global, regional and national background of the study - the cage fish farming in

Lake Victoria, the environmental impacts of cage fish farming, the legal and institutional

framework of aquaculture in Tanzania, the problem statement, objectives of the study, research

questions and the rationale of the study. Part 2 provides the study materials and methods. Part

3 is the literature review, which provides the background information on the environmental and

socio-economic impacts of cage fish farming and the aquaculture policy analysis. Part 4 is the

discussion of findings from the literature. Part 5 provides the conclusion of the findings and

recommendations that the study would wish to be adopted by different stakeholders within the

aquaculture industry.

12

2. Materials and methods

2.1 Description of Study area

2.1.1 Lake Victoria

Lake Victoria (Figure 5), is a transboundary water body shared among three countries Tanzania,

Uganda, and Kenya (Kayombo & Jorgensen, 2006), which is lying within a shallow depression

with a mean depth of about 35m (Sitoki et al., 2010) occupying an area of about 68,800 km2

(Luomba et al., 2016) with a length of about 400km and its breadth is about 320 km2 (Nyamweya,

2017).

Figure 5. Physical features of Lake Victoria (source: Vanderkelen et al (2018).

https://hess.copernicus.org/articles/22/5509/2018/

13

2.1.2 Mwanza Gulf area of Lake Victoria

Particular attention was made to the Mwanza Gulf area of Lake Victoria, Tanzania (Figure 6)

which is an important site for aquaculture and a focus of attention for TAFIRI. The Gulf lies in the

far south of the lake forming an inlet of about 60 km with an average width of about 5 km and

depth of about 25m covering a surface area of about 500 km2. Three cage fish farming sites along

Mwanza Gulf in Lake Victoria were involved in the surveyed area for suitability of cage fish farming

(Figure 3). The sites included Mpanju Fish Farm, Dr. Charles Tizeba fish farm and EF Outdoor

fish farm.

Figure 6: Surveyed area for cage fish farming in the Mwanza Gulf of Lake Victoria,

Tanzania. (Source: TAFIRI, 2015).

https://docplayer.net/28551352-Tanzania-fisheries-research-institute-tafiri.html

14

2.2 Research Methodology

2.2.1 Sources of data and treatment

At the outset of the project the intention was to collect primary data by interviewing cage fish

farmers in Tanzania (see Appendix 1), however due to the pandemic conditions and travel

restrictions it proved impossible to collect such data, even in mobile online format. The study

had to rely on secondary sources of data from published reports and the literature. Data from

the past years, current and future projections were derived from published reports and literature

as well as from technical reports from research institutes such as Tanzania Fisheries Research

Institute (TAFIRI) and from reports obtained from cage farmers in the Mwanza Gulf region.

2.2.2 Literature review methods

The study applied a comprehensive and systematic approach, involving, firstly, an analysis of

government documents, regulations, and/or laws while secondary data was obtained from

scientific journals, articles, and research reports; and administrative data from TAFIRI. Secondly,

a systematic search of global datasets (such as the FAO database) and literature was used to

collate information on the global and regional impacts of cage fish farming. Thirdly,

comprehensive review of published reports and literature were used for understanding and

providing contextual data to be used in identifying the suitability of cage fish farming as a means

of fish production or as a substitute of dwindling fish capture in Lake Victoria, Tanzania.

2.2.3 Data analysis

The physical-chemical parameter values, nutrient level values, and benthic macroinvertebrate

parameters as well as socio-economic impacts of cage fish farming of the study were

referenced with the standards for cage fish farming from TAFIRI (2016; 2018)

15

3. Literature review

This literature review examines the environmental and socio-economics impacts associated with

cage fish farming and evaluates best practices of cage fish farming and future research needs.

3.1 Environmental impacts of cage fish farming

Expansion of cage fish farming systems may lead to increased nutrient concentrations in lakes.

Impacts may include the increase of eutrophication, poor water quality, diseases, and parasite

spread and destruction of ecosystems (Gondwe, Mangaliso John Gibson Symon, 2009;

Kashindye et al., 2015; MENSAH et al., 2018; Mwebaza-Ndawula et al., 2013; Sitoki et al., 2010;

Troell & Berg, 1997). These are now considered in turn.

3.1.1 Nutrients loading in water environments

Extensive cage fish farming in lakes can influence changes in concentrations of nutrients. These

nutrients, phosphorus (P), ammonia (NH4) and nitrogen (N); are important for growth of animals

and plants, however, their excessive release in water columns can result in a number of effects

both healthy and ecological impacts. Nitrogen regulates the developmental rates of algae in

marine ecosystems while phosphorus often limits their development in freshwater ecosystems. In

Lake Victoria water surface, both N and P have low concentrations suggesting the fundamental

limitation in the lake. Thus, a low ratio (N:P) of waste in cages may accelerate the growth of

Nitrogen-fixing organisms in the water columns with increased toxicity which may affect fish,

human and other aquatic organisms (Gondwe et al., 2011).

Excessive discharge of nutrients in the water environment has critical impacts such as overgrowth

of algae and some aquatic plants as well as eutrophication. The escalated growth of these

organisms may result in clogging of water intakes, depletion of dissolved oxygen as they grow,

and blocking of light in deep waters. Eutrophication promotes unsightly algal blooms which can

cause death of fish and other aquatic species hence affecting both animal and plant diversity of

the lake. On the other hand, excessive nitrogen in the form of nitrates in drinking water is

detrimental to young animals as it limits oxygen transportation in bloodstream; and high levels of

phosphorus in the form of phosphates can cause digestive problems (Fiedler et al., 2015;

Kashindye et al., 2015; Rohrlack, 2020). Moreover, dissolved ammonia (NH4) forms a weak base

in water. Unlike N and P, NH4 in water is not toxic to humans; however, high levels of NH4 have

a direct toxic effect to aquatic life. The toxicity depends on the levels of pH and temperature of

water, thus, variations in levels of pH and temperature (low or higher levels) accelerate the toxicity

16

of NH4. Animals are less tolerant of NH4 toxicity than plants. Likewise, invertebrates are more

tolerant to NH4 toxicity than fishes; hence, the growth rate of fish can be affected by high levels

of NH4 toxicity. In addition, bacteria are able to convert NH4 in water to nitrates (nitrification

process), which in turn causes the death of fish and other aquatic organisms due to difficulty in

breathing caused by low dissolved oxygen in water.

Table 1. Nutrient release from cage fish farms into the environment

Location Nutrient Loading

level

Significance

level

Species

cultured

Reference

Lake

Victoria,

Tanzania

N 1034.5 µg/l Minimum

Nile tilapia

(Oreochromis

niloticus)

Kashindye et al.,

(2015)

P 106.8 µg/l Low

NH4 365 µg/l Minimum

Lake

victoria,

Uganda

N 250 µg/l Minimum

Nile tilapia

(Oreochromis

niloticus)

Mwebaza-Ndawula

et al., (2013)

P 150 µg/l Low

NH4 650 µg/l Minimum

Lake

victoria,

Kenya

N 205.5 µg/l Minimum

Nile tilapia

(Oreochromis

niloticus)

Mwainge et al.,

(2021)

P 295.4 µg/l Minimum

NH4 662.8 µg/l Minimum

17

3.1.2 Water quality changes associated with cage farming

The health of fish in cages is influenced by the quality of water. Changes in the quality of water

may result in fish stress, diseases and parasites, a situation, which can lead to poor fish products,

reduced profit and human health impacts (Devi et al., 2017). Since fishes in cages are constantly

supplied with nutrition, nutrients in excess enrich the surrounding water with dissolved organic

and inorganic matters, which can lead to changes in DO, pH, temperature and/or water

transparency (Kashindye et al., 2015). DO can be used as an indication of the degree of pollution

in cage fish farms activities. Water temperature, nutrients and the rate of respiration and

photosynthesis may affect the concentration of DO (Devi et al., 2017; Kashindye et al., 2015).

High temperatures reduce the solubility of oxygen in water hence less oxygen to aquatic

organisms leading to suffocation and finally death whereas high nutrient concentrations lead to

excessive plant growth, causing a decrease in DO due to respiration and decomposition (Devi et

al., 2017). Commonly, the hydrogen ions concentrations (pH) in water columns influence fish

productivity. However, the increase of wastes in water due uneaten feed or other pollutants may

lower the pH whereas the increase in respiration or photosynthesis activities may result in the rise

in pH. Thus, the lower pH, the more acidic the water is while the higher the pH, the more basic it

is (Kashindye et al., 2015; Owuor et al., 2019). Extreme pH (low or higher) kills fishes and other

aquatic organisms directly. For instance, when the pH of freshwater is higher, the water becomes

alkaline which causes death to fishes due to damages of gills and an ability to excrete (Owuor et

al., 2019). Moreover, suspended solid materials from cages due to excess feed and excretions

from fish or from other activities around cage farms reduce the light penetration in deep water

which affect algae and phytoplankton activities (Devi et al., 2017).

18

Table 2 Water quality status in Lake Victoria Tanzania Source: (Kashindye et al., 2015)

Table 3: Water quality status in Lake Victoria, Kenya Source: (Owuor et al., 2019)

19

Table 4. Water quality parameters in Lake Victoria, Uganda (Source: Mwebaza-Ndawula et al.,

2013).

3.1.3 Fish cages, non-native species, diseases and parasites occurrence

Fish escapes from cages is an inevitable global occurrence that threatens the health of both wild

fish and farmed fish. The impacts include the introduction of alien species, disease spread and/or

permanent change in genes of both cultured and wild fish. Studies indicate that about one-third

(32 per cent) of the global marine ecoregions are threatened by the impacts of fish escapees

(Atalah & Sanchez-Jerez, 2020). In addition, poor management of cage fish farming systems can

lead to diseases and parasites spread in cages due to a rise in stress levels, which reduce the

immune system of fishes. Environments with high levels of nutrients attract the growth of bacteria

and fungus, which can cause blocking, and lowering of BOD in cages. Such conditions lead the

stocks to parasitic or disease infections.

20

Figure 7: The health status of cage fish farms in Lake Victoria, Kenya, 2016-2018 Source:

(Mwainge et al., 2021)

21

Table 5. Parasites in cage fish farms in Lake Victoria, Kenya (Ojwala et al., 2018)

22

Table 6. Viral diseases in caged and wild fishes in Lake Victoria (Source: Mugimba et al., 2018)

23

3.1.4 Impacts of cage fish farming on biodiversity

Lake Victoria is endowed with a high number of biodiversity (Sayer et al., 2018; Sayer et al.,

2019). Experience shows that Lake Victoria comprised about 20 sub-families and 600 fish species

mostly (about 80 per cent) occupied by cichlids (Katunzi et al., 2017). Before the intensive fishing

and the invasion of Lates niloticus (Nile perch), the ecosystem of Lake Victoria constituted a large

number of haplochromine species (plates 1-4, TAFIRI). However, fishing intensification and the

introduction of a predator Lates niloticus contributed the decline of the haplochromines, as a result

only the Lates niloticus and Oreochromis niloticus; and the native Rastrineobola argentea

(cyprinid) dominated Lake Victoria (Kayombo and Jorgensen, 2006; Kolding et al., 2014). In

addition, large part of Lake Victoria basin comprise swamps and wetlands which are habitats of

mammals such as crocodiles, hippopotamuses and birds (Okeyo-Owuor et al., 2012) whereby

the Lake banks are dominated by Cyperus papyrus and Miscanthidium violaceum flora (Kansiime

et al., 2007).

Furthermore, cage fish farming practices in Lake Victoria can cause localized and significant

variations on the structure of macroinvertebrate communities. Studies showed an increased

number of pollutant tolerant species in the Lake suggesting that organic compounds probably

from cages (Table 12) have polluted the area.

24

Plate 1: Haplochromine species 1 (Source: TAFIRI)

Plate 2: Haplochromine species 2 (Source: TAFIRI)

Plate 3: Haplochromine species 3 (Source: TAFIRI)

25

Plate 4: Haplochromine species 4 (Source: TAFIRI)

Table 7. Increased macroinvertebrate community in the cage fish farms environment

Pollutant tolerant macroinvertebrate

numerical abundance

Country Reference

Higher number of Chironomus sp. and M.

tuberculata

Uganda Nabirye et al., (2016)

Higher number of Chironomus sp., Bellamya

unicolor and Melanoides tuberculata.

Uganda Mwebaza-Ndawula et

al., (2013)

Higher number of Bellamya unicolor Uganda Egessa et al., (2018)

26

Higher number of B. costulata, Bellamya unicolor

and Melanoides tuberculata.

Tanzania Kashindye et al., (2015)

3.2 Cage culture across Africa

In assessing the scale of cage fish farming in Tanzania in relation to other African countries a

comparative analysis was undertaken. Based on the number of fish farms in African countries,

Ghana leads by having the largest number of cage fish farms (about 36 per cent), with Uganda

being the next by 17 percent, Kenya 16 per cent, Tanzania 13 per cent, Rwanda 8 per cent,

Zimbabwe 3 per cent, Zambia 3 per cent and Malawi is 1.5 per cent (Musinguzi et al., 2019).

About 39 per cent of cage fish farms in African water bodies, Lake Victoria leads with about 12,086

cages (Table 19). Despite the number of cages in African lakes slightly increasing, cage

establishments do not cover a large part of the lakes.

27

Table 8 summary of cage farms in African lakes Source: Musinguzi et al., 2019)

3.3 Socio-economic impacts of cage fish farming

Cage fish farming is a positive venture that may offer a chance for socioeconomic improvements

such as the creation of employment, food security, and improving economic well-being (Tables 9

and 10). Cage fish farming contributes also to the industrial and sector linkage in manufacturing,

construction and transportation (Aura et al., 2018; Ghana & Brummett, 2010). The degrees of

benefits vary from one area to another due to differences in farming practices (Anjejo, 2019) as

well as on other factors such as the type of species cultured, the level of management, level of

investment, the availability and reliability of fish market (Aura et al., 2018). Tables 10 and 11 have

characterized the socio-economic benefits of cage farming in Lake Victoria. A large number of

fish farmers are men while women participate in harvesting, possessing, trading, and marketing

activities. This suggests that women in the society benefit at least as much if not more from cage

28

farming activities than men (MENSAH et al., 2018). The middle-aged group, mostly elite, achieves

the highest productivity of the sector. The group seems to be innovative and brave to invest more

on cage farms (Biswas et al., 2018).

Table 9 Socio-economic impacts of cage farming in Lake Victoria

Author Location Cage

farmers

Job

created/expected

(People)

Dominant

age

employed

(years)

Income

generated

(USD)

Total

food/fish

supply (kg)

Aura et al.,

(2018)

Lake

Victoria,

Kenya

39 1,343 36-45 2,832

mean

household

monthly

2,134,027

Mwamburi

et al.,

(2021)

Lake

Victoria,

Kenya

73 6,756 31-44 137 mean

household

monthly

1,890,000

Mbowa et

al., (2017)

Lake

Victoria,

Uganda

28 120,757 32-45 135 mean

household

monthly

1,349,000

29

Table 10 Socio-economic impacts of cage fish farming

Article Location Socioeconomic benefits Observations

Anjejo (2019) Lake Victoria-

Kenya

Cage fish farming

contributes to the

livelihoods of communities

along in terms of food

supply, employment,

income generation,

businesses and assets

(houses)

Most fish farms are

owned by foreign

investors, locals (men)

involves as cage

laborers while women

involve in the fish trade

Mwamburi et

al., (2021)

Lake Victoria-

Kenya

Cage fish farming and fish

trading in are major

occupational practices,

creating employment,

income generation (164-

654USD/day), food supply

and improvement of rural

infrastructures such as

roads

Majority of cage farm

owners are individuals

with few group owned

farms

Okorie, P. U.

(2004)

Oguta lake -

Nigeria

Cage fish farming

contributes to local

communities incomes,

creation of employment

and fish production

The activity is

essentially enhancing

the poor communities,

which do not have

access to land for other

forms of production

30

MENSAH et al.,

(2018)

Volta lake-

Ghana

The cage aquaculture

sector supports the

livelihoods of the people

through job creation,

poverty reduction, trade,

and food supply

Higher number of

women employed in

harvesting activities

Phillips &

DeSilva, (2004)

Asia Cage fish farming benefits

communities in terms of

employment, income

generation, food supply

and alternative livelihoods

The increased benefits

to community is due to

improved technology,

quality seeds and feed

3.4 Aquaculture Policy analysis

The Fisheries Act, 2003 with its Regulations (The Fisheries Regulations, 2009) currently governs

the management and development of aquaculture in Tanzania. It ensures the long-term

sustainable use of aquaculture products by integrating all laws on aquaculture to permit the

growth of the sector in Tanzania. The Act streamlines the sector to respond directly to transpiring

matters concerning aquaculture development, and to comply with other rules and regulations for

protecting the environment from adverse impacts, which may arise from aquaculture activities.

Table 12 summarizes the legal provisions for aquaculture governance in Tanzania

31

Table 11 Legal provisions for aquaculture management in Tanzania

Environmental/Social

Aspect

Law/Regulation Provision/Article/Section Adherence

Aquaculture,

environment and other

human activities

The Fisheries

Act, 2003

11.-(1) “The Director shall

in collaboration with local

authorities and other

relevant bodies ensure

that”-

(a) “aquaculture

development is

ecologically sustainable

and allows rational use of

the resource shared by

aqua culture and other

activities”

Feasibility studies

are conducted by an

authorized

organization/institute

(TAFIRI) prior to

establishment of

aquaculture farms in

order to ascertain the

suitability of the

proposed site. This

help to identify the

ecological,

environmental and

social implications of

the activity in the

area

32

The Fisheries

Regulations,

2009

35. “Aquaculture practices

shall not be conducted in

such a manner as to

disrupt the integrity of the

environment”.

36. - (1) “A person shall not

undertake aquaculture

practices in a manner that

may adversely obstruct

water sources or divert

water used for other

human activities”. (2)

“Every aqua farmer shall

obtain water user right and

may collaborate with other

water users to eliminate

conflicts in water use”.

Fish farmers acquire

licenses, permits,

certificates and

guidelines prior to

establishment of

their projects. This

promote

sustainability of the

establishments and

avoids water use

conflicts

33

Environmental Impact

Assessment (EIA)

The Fisheries

Regulations,

2009

32.- “An aqua farmer may

seek an expert opinion

prior to the practice of

aquaculture which shall

include"-

(e) “an approval for use of

land and water right for that

purpose by a community

concerned or any relevant

authority”.

Prior to

commencement of

their projects, fish

farmers with

consultation of

environmental

experts conduct

EIA in order to

foresee the

environmental and

social impacts of

their undertakings.

This is in line with

section 83(1) of the

EMA, 2004 which

provides that

“Notwithstanding

the provisions of

subsection (2) of

section 82,

environmental

impact

assessments shall

be conducted by

experts or firms

whose names and

qualifications are

registered as such

by the Council”.

Control and monitoring

of aquaculture

practices

The Fisheries

Regulations,

2009

15.-(1) “Local authorities

shall monitor the

performance of

Environmental

Managers in

collaboration with

34

aquaculture practices

within areas, which form

part of their jurisdiction”.

33.- “For the purpose of

monitoring and control of

practices and diseases on

large scale aquaculture the

following are required-

(a) “an environmental

impact assessment carried

out by an approved

relevant authority”;

(b) “water used for

aquaculture practices shall

be free from petroleum

products, agro-chemicals

leeches, toxic algae,

contaminated domestic

sewage, and industrial

effluent and shall be

monitored regularly”;

41.- (1) “Every aqua farmer

shall ensure that”- (a)

“effluents from aqua farm

do not cause pollution on

other aquatic or terrestrial

ecosystem”

BMUs leaders

conduct regular

inspections in order

to check for

observance and

adherence of

regulations put for

aquaculture

practices in the area.

Fish farmers also

conduct their

quarterly and

annually self-

monitoring of their

facilities for

evaluation and

correction of their

deviations to

standards and

regulations if any

35

4.0 Discussion

Cage fish farming is a high-yielding type of aquaculture with social advantages like creation of

jobs, food supply and income generation. Although the practice is still a new innovation in

Tanzania, the number of cages in Lake Victoria is increasing which is a signal that the practice

will improve fish capture and hence assurance of food security, employment and income stability

to the lakeside community (Kashindye et al., 2015; Njiru, J. M. et al., 2019). However, resources

are devoted to better development and the production of seed is still a private-based sector

(Adeleke et al., 2020).

4.1 Environmental impacts of cage fish farming in Lake Victoria

The biophysical status of Lake Victoria is drastically changing due to human manipulations such

as the expanded cage farming systems, which may lead to change in functioning of the Lake

ecosystem (Nyamweya et al., 2020). High release of nutrients from cages may result in the

increase in nutrient concentrations in lakes. The impacts may include the increase of

eutrophication, lowering of water quality, diseases, and parasite spread (Kashindye et al., 2015;

MENSAH et al., 2018).

4.1.1 Impacts of nutrient loading in water environments

Table 1 summarizes the nutrient loading from cages in Lake Victoria. Three published studies on

nutrient loading from cage farms in Lake Victoria found that the variation in nutrient concentrations

did not show a notable impact on water quality in the Lake. Fluctuations in levels of nutrient

concentrations along cages and open waters did not show any evidence that these levels could

lead to eutrophication in the Lake. Hence, although cage fish farming may raise environmental

concerns, the studies showed that there is no any observed evidence that cage farming caused

an immense eutrophication in the Lake. However, these results could be because of the sample

size being small enough to give reliable results and/or because of small number of cages in a

given area, the openness nature of cage areas to wind currents that speeds the dispersion of

wastes to the surrounding environment, and rapid removal of wastes by wild fishes in the

surrounding environment. In addition, the difference in sampling time (before or after feeding) can

also cause the variability in levels of the nutrient concentrations measured at the cage stations.

On the other hand, with extensive cage production like in the Kenya and Uganda side of Lake

Victoria, a different scenario could be explained, whereby increased waste generation in fish

cages can considerably pollute the environment and the cultured fish. Similar results can be

36

observed in situations where the increased values of nutrients may result from low water

movement caused by the fish cages and/ or from other sources such as agricultural activities.

4.1.2 Water quality changes associated with cage farming

Excessive cage fish feed contents and other biological processes may contribute to lowering the

quality of water. The three published studies on the impacts of cage fish farming on the quality of

water (Tables 2-4) found that the feed nutrients from cages did not cause a significant effect on

the selected water quality parameters. The levels of DO, pH, temperature and turbidity in all four

study areas was found to be in allowable limits suggesting that the nutrients input from cages did

not cause a significant impact on the water quality of the Lake. The fluctuation on levels of the

selected parameters implied a slight impact of nutrients on water quality of the study areas. This

suggests that the natural water currents of the Lake probably minimized the oxygen depletion in

the waters, and the pH values in all four studies fluctuated nearly neutral to alkalinity suggesting

a negligible impact on water quality. Likewise, the suspended solids in the water column and

water temperature in all four-study areas fluctuated slightly suggesting that cage farming did not

substantially affect the water quality. In general, although nutrient contents from cages may affect

the water quality parameters, there is no empirical evidence on the significant affecting of these

nutrients on these selected water quality parameters hence no effect on water quality. It is also

suggested that the results may have been contributed by the non-existence of small changes in

weather patterns in the Lake, hence no impact on water quality. However, as cage-farming

activities are expected to increase, nutrient loading will increase leading to changes in DO, pH,

temperature and suspended solids, hence affecting aquatic life.

4.1.3 Fish cages, non-native species, diseases and parasites occurrence

Fish escapes from cages is an inevitable global occurrence that threatens the health of both wild

fish and farmed fish. The impacts include the introduction of alien species, disease spread and/or

permanent change in genes of both cultured and wild fish. Three published studies on diseases

and parasites occurrence associated with cage fish farming in Lake Victoria (Figure 7, Tables 5

and 6) found that there is no any observed evidence that varying degrees of infections and

diseases in fish cages in Lake Victoria have significant impacts to caged fishes and/or zoonotic

impacts. For instance, in Lake Victoria, Kenya with about 3,600 cages, only about 10 cage

establishments were found with diseases and parasite infections (Figure 7). These results could

be because of the sample size being small enough to give reliable results, however, with extensive

37

cage production, increased waste generation from cages is expected which can lead to lowering

of water quality, hence disease and parasites spreading in Lake Victoria. In addition, although

fish escaping from cages is an inevitable occurrence, the studies did not find any evidence of

escapees in the Lake probably the studies concentrated only on diseases and parasites and/or

because the cultured species (commonly the Nile tilapia) is, the same species available as wild

fish, hence difficult to distinguish between escapees and wild fishes. Thus, for sustainable cage

fish farming, strict measures including advanced research should be considered to counteract the

impacts of diseases and parasites in Lake Victoria.

4.1.4 Impacts of cage fish farming on biodiversity

Lake Victoria hosts a high freshwater native biodiversity, altogether 651 species, including 204

species endemic. However, the human-induced impacts including aquaculture activities in the

basin are known to be the causes of the changes in the number of species and in their endemism

(Sayer et al., 2018; Sayer et al., 2019). Studies show that the introduction of new fishing practices

(such as aquaculture) has changed the ecology of the Lake whereby the increased number of

Nile perch and eutrophication contributed to the disappearance of the native Labeobarbus

microbarbis in the region (Plates 1-4). Before the intensive fishing and the introduction of Lates

niloticus (Nile perch), only the fishing of native species caused the change in the composition of

fish in Lake Victoria. Moreover, cage fish farming practices in Lake Victoria have caused localized

and significant variations on the structure of macroinvertebrate communities. Four published

studies on macroinvertebrate community changes associated with cage fish farming in Lake

Victoria (Table 7) found evidence of an increased number of pollutant tolerant macroinvertebrates

in Lake Victoria suggesting that the Lake has been polluted by organic compounds probably from

cages and/or other sources. On the other hand, the presence of a number of Labeo victorianus

and Brycinus sadileri is probably due to the presence of river Nyashishi entrance to the lake

whereby through it the diadromous species like Labeo migrate to the river for breeding (TAFIRI,

2018). Although the studies did not show significant effects of cage culture on biodiversity,

advanced research to explore the environmental effects of cage culture in Lake Victoria is

required in order to assess the future cage culture development of Lake Victoria.

38

4.2 Cage fish farming and the community

Tables 9 and 10 summarizes that cage fish farming significantly improves the livelihoods, in

particular, employment, income, food, trading and infrastructures. This is implying that cage fish

farming has contributed positively to the wellbeing lakeside community through creation of jobs,

generating income, and ensuring food security. Hence, Lake Victoria contributes to the

improvement of livelihood conditions of the fish farming societies. However, all of the five

published studies on the socioeconomic impacts of cage fish farming (Table 9) found that the

sector is male-dominated with women participating in harvesting and processing activities. Since

women are directly employed in harvesting and processing sections as well as they participate

directly in the trading, the studies suggested that men benefit less than women do from the

activity. The male dominance in the sector suggests the belief that women are not allowed to

own assets particularly in the fishery industry. Moreover, studies found that the sector is

dominated by middle-aged groups (30-45 years) suggesting that young people dominate the

fisheries workforce, meaning that young people are faced by high unemployment problems in the

area. The studies also found that, cage farmers engage in other socioeconomic activities such as

agriculture, some employed in other sectors such as teaching or self-employment. This suggests

that people in Lake Victoria do not consider cage farming as the sole or primary employment

sector. On the other hand, the mode of cage farming practices, improved technology, quality

seeds and feed, species cultured, the level of management, level of investment, the availability

and reliability of the fish market influences the success of fish farming. Thus with improved

technology and level of management as well as availability of quality seeds and feed, sustainable

cage fish farming is expected to contribute to the improvement of livelihood of people along Lake

Victoria, at the same time safeguarding the environment of the Lake.

4.3 Compliance status of cage fish farmers on aquaculture regulations

The National Fisheries Act, 2003 of Tanzania with its Regulations (The Fisheries Regulations,

2009) requires all cage farmers to seek and obtain permits, certificates and/or licenses such as

water user right prior to establishment of their undertakings. Section 11(1) of the The Fisheries

Act, 2003 provides that “The Director shall in collaboration with local authorities and other relevant

bodies ensure that- (a) aquaculture development is ecologically sustainable and allows rational

use of the resource shared by aqua culture and other activities”; whereas Regulation 36(2) of The

Fisheries Regulations, 2009 provides that “Every aqua farmer shall obtain water user right and

may collaborate with other water users to eliminate conflicts in water use”. Authorized institutes

39

such as TAFIRI (on the side of Lake Victoria, Tanzania) conducts feasibility studies to ascertain

the suitability of the site (for identification of the ecological and socioeconomic implications) before

implementation of the project. Permit acquisition allows the promotion of sustainable projects and

avoids conflicts among water users. In addition, Regulation 32 of The Fisheries Regulations, 2009

which provides that “An aqua farmer may seek an expert opinion prior to the practice of

aquaculture which shall include”- (e) “an approval for use of land and water right for that purpose

by a community concerned or any relevant authority.” This is in line with section 83(1) of the EMA,

2004 which provides that “Notwithstanding the provisions of subsection (2) of section 82,

environmental impact assessments shall be conducted by experts or firms whose names and

qualifications are registered as such by the Council”. EIA studies help to identify the ecological

and socioeconomic implications of the activity in the area and allows the predictions of the

mitigation measures of any anticipated impacts, which may result from the activity. Moreover,

cage farmers with collaboration with local authorities are required to conduct monitoring and

control of their farming activities in accordance with Regulation 15(1) of The Fisheries

Regulations, 2009 which provides that “Local authorities shall monitor the performance of

aquaculture practices within areas, which form part of their jurisdiction” concurring with Regulation

41(1) of The Fisheries Regulations, 2009 which provides that “Every aqua farmer shall ensure

that”- (a) “effluents from aqua farm do not cause pollution on other aquatic or terrestrial

ecosystem”.

Despite the fact that cage fish farming can cause adverse impacts on the water environment, all

of the five published studies found that currently there are insignificant effects of cage farm

activities in Lake Victoria on neither water quality nor diseases and parasite spreads. This can

lead to suggestions that cage farm owners either complying to aquaculture rules and regulations

or aquaculture Policy in Lake Victoria are strong enough to properly guide the management of

aquaculture activities. Only one study out of five studies found one farm with violation of cage site

location. This may suggest that the farmer owner was not aware of the existing rules due to lack

of education and awareness on sustainable aquaculture activities. Since the cage fish farming

system is expected to increase with an anticipated increase of negative impacts on the water

quality and biodiversity, regulatory and environmental framework, technical standards for cage

fishing equipment and feed quality should be considered for future management and control of

cage farming investments in the Lake. This should not leave behind education and public

awareness on sustainable aquaculture practices.

40

5.0 Conclusion and recommendations

Cage fish farming practice is an anticipated venture to increase fish production in Lake Victoria,

Tanzania. It is a high-yielding type of aquaculture with important social and economic benefits

such as the creation of jobs, food security, income generation, and improvement of infrastructures

for the communities along the Lake. The literature showed that currently, cage fish farming

practices in the Lake have few negative impacts on the Lake environment. Although the variations

in nutrient concentration in the Lake is expected to be high due to the increased cage farms

whereby more feed may be consumed by caged fishes, most studies showed that the impacts of

nutrient release from fish cages were minimal with insignificant impacts on the Lake environment.

The situation can be explained by a number of reasons such as (1) the cage fish capacity is low,

hence little release of wastes from feed (2) the consumption rate of wastes by wild fishes

aggregating the cages is high (3) cage wastes are rapidly dispersed by water currents due to

openness nature of the Lake to wind currents (4) differences in sampling time which is done

before or after feeding at the cage stations and/or (5) the study size sample small because some

of the studies on cage farms were done as experimental trials (for example on the side of Lake

Victoria, Tanzania) (Kashindye et al., 2015). On the other hand, the observed increase in values

of nutrients may be due to the release of uneaten feed from the cages or by low water movement

caused by the fish cages and/ or from other activities such as agricultural activities along the Lake.

The variations in levels on selected physicochemical parameters (pH, DO, temperature and water

transparency) were within allowable limits suggesting that no immediate recognized impacts of

the fish cage facilities on water quality probably due to (1) the non-existence of small changes in

weather patterns in the Lake and/or (2) there is moderate nutrient loading from cages. However,

there is an indication of the plausible impacts of cage activities on the quality of water in the

studied cage fish farms. In addition, cage fish farming may affect the composition of

macroinvertebrate communities, which can be observed by a change in the composition of

species as well as the increase of pollutant-tolerant organisms in the Lake.

Considering that the cage fish farming system is expected to increase, impacts on the water

quality and biodiversity of Lake Victoria linked with cage fish farming can be avoided or minimized

by:-

1. Changing policy options in order to strengthen the regulatory and environmental

framework determinants, which will manage the cage farming investors in the Lake.

2. Policy-makers should introduce technical standards for cage fishing equipment, seed and

feed quality with a mechanism to enforce the standards

41

3. Cage farmers use appropriate technical instructions and adopt good cage fish farming

production schemes (such as better management practices and proper cage sitting) as

well as complying with aquaculture rules and regulations

4. Undertaking future studies on the impacts of cage fish farming on the water quality and

biodiversity

5. Controlling the fish stock relative to cage farm size

6. Routine monitoring of sediment and water quality along cages as well as monitoring of the

types of feed

7. Qualified and trained workers or managers to use modern technologies for fish farming

techniques development

8. Expanding the fish farm rotation and using self–sufficiency cultivated crops for feed

ingredients

42

References

Adeleke, B., Robertson-Andersson, D., Moodley, G., & Taylor, S. (2020). Aquaculture in africa: A

comparative review of egypt, nigeria, and uganda vis-À-vis south africa. Reviews in Fisheries

Science & Aquaculture, 1-31. https://doi.org/10.1080/23308249.2020.1795615

Anjejo, K. O. (2019). No title. Cage Fish Farming and its Effects on Livelihoods of Fisherfolk within

Anyanga Beach, Siaya County, Kenya., http://erepository.uonbi.ac.ke/handle/11295/108928

Aura, C. M., Musa, S., Yongo, E., Okechi, J. K., Njiru, J. M., Ogari, Z., Wanyama, R., Charo‐Karisa,

H., Mbugua, H., & Kidera, S. (2018). Integration of mapping and socio‐economic status of cage

culture: Towards balancing lake‐use and culture fisheries in lake victoria, kenya. Aquaculture

Research, 49(1), 532-545. https://doi.org/10.1111/are.13484

Balirwa, J. S. (2007). Ecological, environmental and socioeconomic aspects of the lake victoria's

introduced nile perch fishery in relation to the native fisheries and the species culture potential:

Lessons to learn. African Journal of Ecology, 45(2), 120-129. https://doi.org/10.1111/j.1365-

2028.2007.00753.x

Bostock, J., McAndrew, B., Richards, R., Jauncey, K., Telfer, T., Lorenzen, K., Little, D., Ross, L.,

Handisyde, N., & Gatward, I. (2010). Aquaculture: Global status and trends. Philosophical

Transactions of the Royal Society B: Biological Sciences, 365(1554), 2897-2912.

https://doi.org/10.1098/rstb.2010.0170

Bouwmeester, M. M., Goedknegt, M. A., Poulin, R., & Thieltges, D. W. (2021). Collateral diseases:

Aquaculture impacts on wildlife infections. Journal of Applied Ecology, 58(3), 453-464.

https://doi.org/10.1111/1365-2664.13775

Brummett, R. E., Lazard, J., & Moehl, J. (2008). African aquaculture: Realizing the potential. Food

Policy, 33(5), 371-385. https://doi.org/10.1016/j.foodpol.2008.01.005

Casadevall, M., Rodríguez-Prieto, C., Torres, J., Eira, C., Marengo, M., Lejeune, P., Merciai, R., &

Richir, J. (2021). Marine aquaculture impacts on marine biota. Frontiers in Marine Science, 8,

162. https://doi.org/10.3389/fmars.2021.615267

Challouf, R., Hamza, A., Mahfoudhi, M., Ghozzi, K., & Bradai, M. N. (2017). Environmental

assessment of the impact of cage fish farming on water quality and phytoplankton status in

43

monastir bay (eastern coast of tunisia). Aquaculture International, 25(6), 2275-2292.

https://doi.org/10.1007/s10499-017-0187-1

Chenyambuga, S. W., Mwandya, A., Lamtane, H. A., & Madalla, N. A. (2014). Productivity and

marketing of nile tilapia (oreochromis niloticus) cultured in ponds of small-scale farmers in

mvomero and mbarali districts, tanzania. Livestock Research for Rural Development, 26(3), 3-12.

https://lrrd.cipav.org.co/lrrd26/3/chen26043.htm

Cowx, I. G., & Ogutu‐Owhayo, R. (2019). Towards sustainable fisheries and aquaculture

management in the african great lakes. Fisheries Management and Ecology, 26(5), 397-405.

https://doi.org/10.1111/fme.12391

Çulha, S. T., & Karaduman, F. R. (2020). The influence of marine fish farming on water and

sediment quality: Ildır bay (aegean sea). Environmental Monitoring and Assessment, 192(8), 1-

10. https://doi.org/10.1007/s10661-020-08487-9

Egessa, R., Pabire, G. W., & Ocaya, H. (2018). Benthic macroinvertebrate community structure in

napoleon gulf, lake victoria: Effects of cage aquaculture in eutrophic lake. Environmental

Monitoring and Assessment, 190(3), 1-10.

http://eds.a.ebscohost.com/eds/pdfviewer/pdfviewer?vid=0&sid=a4a5b1fe-fb0c-4012-a90c-

9b4c152dc1a0%40sdc-v-sessmgr01

Food and Agriculture Organization of the United Nations ([FAO] (2012). United Republic of Tanzania

- National Aquaculture sector

overview. http://www.fao.org/fishery/countrysector/naso_tanzania/en.

Food and Agriculture Organization of the United Nations ([FAO] (2020). The State of World

Fisheries and Aquaculture 2020. https://doi.org/10.4060/ca9229en

Garlock, T., Asche, F., Anderson, J., Bjørndal, T., Kumar, G., Lorenzen, K., Ropicki, A., Smith, M.

D., & Tveterås, R. (2020). A global blue revolution: Aquaculture growth across regions, species,

and countries. Reviews in Fisheries Science & Aquaculture, 28(1), 107-116.

https://doi.org/10.1080/23308249.2019.1678111

Gephart, J. A., Golden, C. D., Asche, F., Belton, B., Brugere, C., Froehlich, H. E., Fry, J. P., Halpern,

B. S., Hicks, C. C., & Jones, R. C. (2020). Scenarios for global aquaculture and its role in human

44

nutrition. Reviews in Fisheries Science & Aquaculture, 1-17.

https://doi.org/10.1080/23308249.2020.1782342

Ghana, C., & Brummett, R. (2010). Social and economic benefits of commercial aquaculture in rural

communities: A case study of two commercial cage culture farms in ghana.

https://www.sarnissa.stir.ac.uk/wp-content/uploads/2020/12/Social-and-economic-benefits-of-

commercial-aquaculture-in-rural-communities-Ghana-Asmah-1-2010.pdf

Gondwe, Mangaliso John Gibson Symon. (2009). Environmental impacts of cage aquaculture in the

southeast arm of lake malawi: Water and sediment quality and food web changes.

https://www.sarnissa.stir.ac.uk/wp-content/uploads/2020/12/Social-and-economic-benefits-of-

commercial-aquaculture-in-rural-communities-Ghana-Asmah-1-2010.pdf

Halwart, M., & Moehl, J. F. (2006). FAO regional technical expert workshop on cage culture in africa,

20-23 october 2004, entebbe, uganda. Food & Agriculture Org.

https://books.google.se/books?hl=en&lr=&id=DrTLHkV7SIAC&oi=fnd&pg=PR3&dq=Halwart,+M.,+

%26+Moehl,+J.+F.+(2006).+FAO+regional+technical+expert+workshop+on+cage+culture+in+af

rica,+20-

23+october+2004,+entebbe,+uganda.+Food+%26+Agriculture+Org.+&ots=AILLEpwdCJ&sig=N

4uAz2ehRQBdQTDoVS3BS0Ge1Jg&redir_esc=y#v=onepage&q=Halwart%2C%20M.%2C%20

%26%20Moehl%2C%20J.%20F.%20(2006).%20FAO%20regional%20technical%20expert%20

workshop%20on%20cage%20culture%20in%20africa%2C%2020-

23%20october%202004%2C%20entebbe%2C%20uganda.%20Food%20%26%20Agriculture%

20Org.&f=false

Hecht, T. (2006). Regional review on aquaculture development for sub-saharan africa-2005.

https://epub.sub.uni-hamburg.de/epub/volltexte/2008/632/pdf/C1017_4.pdf

Kashindye, B. B., Nsinda, P., Kayanda, R., Ngupula, G. W., Mashafi, C. A., & Ezekiel, C. N. (2015).

Environmental impacts of cage culture in lake victoria: The case of shirati bay-sota, tanzania.

SpringerPlus, 4(1), 475. https://doi.org/10.1186/s40064-015-1241-y

45

Limbu, S. M., Mgaya, Y. D., Hoza, R., & Shoko, A. P. (2017). Aquaculture and fisheries extension.

in: Mgaya, YD and mahongo, SB (editors), lake victoria fisheries resources: Research and

management in tanzania. (). Springer, Switzerland. http://hdl.handle.net/20.500.11810/5240

Martinez-Porchas, M., & Martinez-Cordova, L. R. (2012). World aquaculture: Environmental impacts

and troubleshooting alternatives. The Scientific World Journal, 2012

https://doi.org/10.1100/2012/389623

MENSAH, V. F., ANNANG, T. Y., & OFORI, B. D. (2018). Environmental and socioeconomic impact

of cage aquaculture at kpeve tornu section of the volta lake, ghana. International Journal of

Bonorowo Wetlands, 8(2), 84-95. https://doi.org/10.13057/bonorowo/w080205

Mmanda, F. P., Mulokozi, D. P., Lindberg, J. E., Norman Haldén, A., Mtolera, M., Kitula, R., &

Lundh, T. (2020). Fish farming in tanzania: The availability and nutritive value of local feed

ingredients. Journal of Applied Aquaculture, , 1-20.

https://doi.org/10.1080/10454438.2019.1708836

Mmochi, A. J. (2011). Overview of aquaculture activities in tanzania. Mariculture in the WIO Region-

Challenges and Prospects, (11), 9. http://advanceafrica.co.za/articles-

TomHecht/Mariculture%20in%20the%20WIO%20_%20Challenges%20and%20prospects.pdf#p

age=19

Mwainge, V. M., Ogwai, C., Aura, C. M., Mutie, A., Ombwa, V., Nyaboke, H., Oyier, K. N., & Nyaundi,

J. (2021). An overview of fish disease and parasite occurrence in the cage culture of oreochromis

niloticus: A case study in lake victoria, kenya. Aquatic Ecosystem Health & Management, 24(1),

43-55. https://read.dukeupress.edu/aehm/article/24/1/43/173900/An-overview-of-fish-disease-

and-parasite

Mwamburi, J., Yongo, E., Omwega, R., & Owiti, H. (2021). Fish cage culture in lake victoria (kenya):

Fisher community perspectives on the impacts and benefits for better sustainable management.

https://www.fisheriesjournal.com/archives/2021/vol9issue4/PartA/9-3-54-344.pdf

Mwebaza-Ndawula, L., Kiggundu, V., Magezi, G., Naluwayiro, J., Gandhi-Pabire, W., & Ocaya, H.

(2013). Effects of cage fish culture on water quality and selected biological communities in

northern lake victoria, uganda. Uganda Journal of Agricultural Sciences, 14(2), 61-75.

https://www.ajol.info/index.php/ujas/article/view/126328

46

Musinguzi, L., Lugya, J., Rwezawula, P., Kamya, A., Nuwahereza, C., Halafo, J., Kamondo, S.,

Njaya, F., Aura, C., & Shoko, A. P. (2019). The extent of cage aquaculture, adherence to best

practices and reflections for sustainable aquaculture on african inland waters. Journal of Great

Lakes Research, 45(6), 1340-1347. https://doi.org/10.1016/j.jglr.2019.09.011

Nabirye, H., Mwebaza-Ndawula, L., Bugenyi, F., & Muyodi, F. J. (2016). The evaluation of cage fish

farming effects on water quality using selected benthic macro-invertebrate community parameters

in the napoleon gulf, northern lake victoria. International Journal of Fisheries and Aquatic Studies,

4(1), 42-50. https://www.fisheriesjournal.com/archives/2016/vol4issue1/PartA/3-2-69.pdf

Njiru, J. M., Aura, C. M., & Okechi, J. K. (2019). Cage fish culture in lake victoria: A boon or a

disaster in waiting? Fisheries Management and Ecology, 26(5), 426-434.

https://doi.org/10.1111/fme.12283

Njiru, J., van der Knaap, M., Kundu, R., & Nyamweya, C. (2018). Lake victoria fisheries: Outlook

and management. Lakes & Reservoirs: Research & Management,

23(2). https://doi.org/10.1111/lre.1222

Njiru, M., Kazungu, J., Ngugi, C. C., Gichuki, J., & Muhoozi, L. (2008). An overview of the current

status of lake victoria fishery: Opportunities, challenges and management strategies. Lakes &

Reservoirs: Research & Management, 13(1), 1-12. https://doi.org/10.1111/j.1440-

1770.2007.00358.x

Ojwala, R. A., Otachi, E. O., & Kitaka, N. K. (2018). Effect of water quality on the parasite

assemblages infecting nile tilapia in selected fish farms in nakuru county, kenya. Parasitology

Research, 117(11), 3459-3471. https://doi.org/10.1007/s00436-018-6042-0

Orina, P., Ogello, E., Kembenya, E., Muthoni, C., Musa, S., Ombwa, V., Mwainge, V., Abwao, J.,

Ondiba, R., & Kengere, J. (2021). The state of cage culture in lake victoria: A focus on

sustainability, rural economic empowerment, and food security. Aquatic Ecosystem Health &

Management, 24(1), 56-63. https://doi.org/10.14321/aehm.024.01.09

Orina, P. S., Ogello, E., Kembenya, E., Githukia, C., Musa, S., Ombwa, V., Mwainge, V. M., Abwao,

J., Ondiba, R. N., & Okechi, J. K. (2018). State of cage culture in lake victoria, kenya.

https://repository.maseno.ac.ke/handle/123456789/2258

47

Orinda, M., Okuto, E., & Abwao, M. (2021). Cage fish culture in the lake victoria region: Adoption

determinants, challenges and opportunities. International Journal of Fisheries and Aquaculture,

13(2), 45-55. https://academicjournals.org/journal/IJFA/article-full-text-pdf/3F2D5B967327.pdf

Owuor, J. B., Were, K. P., & Ngodhe, S. O. (2019). Impacts of oreochromis nilticus cage culture on

water quality of winam gulf of L. victoria, kenya.

http://41.89.203.227/bitstream/handle/123456789/2145/Impacts%20of%20Oreochromis%20Nilti

cus%20Cage%20Culture.pdf?sequence=1&isAllowed=y

Rohrlack, T. (2020). Hypolimnetic assimilation of ammonium by the nuisance alga gonyostomum

semen. AIMS Microbiology, 6(2), 92. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7326729/

Rukanda, J. J., & Sigurgeirsson, O. (2018). Evaluation of aquaculture development in tanzania.

https://www.grocentre.is/static/gro/publication/353/document/janeth16aprf.pdf

Sayer, C. A., Máiz-Tomé, L., Akwany, L. O., Kishe-Machumu, M. A., Natugonza, V., Whitney, C.

W., Omondi, R., Nshutiyayesu, S., & Kabuye, C. S. (2018). The importance of freshwater species

to livelihoods in the lake victoria basin. Freshwater Biodiversity in the Lake Victoria Basin.IUCN

Global Species Programme.

https://www.zef.de/uploads/tx_zefportal/Publications/3cwhitney_download_Sayer%20et%20al%20

2018%20407.pdf

Shava, E., & Gunhidzirai, C. (2017). Fish farming as an innovative strategy for promoting food

security in drought risk regions of zimbabwe. Jàmbá: Journal of Disaster Risk Studies, 9(1), 1-10.

http://dx.doi.org/10.4102/jamba.v9i1.491

Shoko, A. P., Msuya, F. E., Mmochi, A. J., Wetengere, K., Lamtane, H. A., Kajitanus, O. O., &

Mgaya, Y. D. (2011). The status and development of aquaculture in tanzania, east africa.

http://hdl.handle.net/123456789/1418

Sitoki, L., Gichuki, J., Ezekiel, C., Wanda, F., Mkumbo, O. C., & Marshall, B. E. (2010). The

environment of lake victoria (east africa): Current status and historical changes. International

Review of Hydrobiology, 95(3), 209-223. https://doi.org/10.1002/iroh.201011226

Tacon, A. G. (2020). Trends in global aquaculture and aquafeed production: 2000–2017. Reviews

in Fisheries Science & Aquaculture, 28(1), 43-56.

https://doi.org/10.1080/23308249.2019.1649634

48

Tacon, A. G., & Halwart, M. (2007). Cage aquaculture: A global overview. FAO Fisheries Technical

Paper, 498, 3.

https://books.google.se/books?hl=en&lr=&id=myCXhIIWeLoC&oi=fnd&pg=PA3&dq=Tacon,+A.+G

.,+%26+Halwart,+M.+(2007).+Cage+aquaculture:+A+global+overview.+FAO+Fisheries+Techni

cal+Paper,+498,+3.+&ots=E1DxB0LGC9&sig=X3c7xYftNlqFqWOI0ljKPsXA0qs&redir_esc=y#v

=onepage&q&f=false

The Environmental Management Act, 2004.

http://www.tzdpg.or.tz/fileadmin/_migrated/content_uploads/Environmental_Management_Act_0

4.pdf

The Fisheries Regulations, 2009

https://trade.tanzania.go.tz/media/The%20Fisheries%20Regulations%20,2009.pdf

The National Fisheries Act, 2003. http://repository.businessinsightz.org/handle/20.500.12018/374

Tanzania Fisheries Research Institute Act, 2016.

http://www.fao.org/faolex/results/details/en/c/LEX-FAOC162775/

van der Heijden, Peter GM, Shoko, A. P., van Duijn, A. P., Rurangwa, E., & Bolman, B. (2018). No

title. Review and Analysis of Small-Scale Aquaculture Production in East Africa: Part 3.

Tanzania. https://library.wur.nl/WebQuery/wurpubs/545024

Vanderkelen, I., van Lipzig, N. P. M., and Thiery, W.: Modelling the water balance of Lake Victoria

(East Africa) – Part 1: Observational analysis, Hydrol. Earth Syst. Sci., 22, 5509–5525

https://hess.copernicus.org/articles/22/5509/2018/

Yogev, U., Barnes, A., Giladi, I., & Gross, A. (2020). Potential environmental impact resulting from

biased fish sampling in intensive aquaculture operations. Science of the Total Environment, 707,

135630. https://doi.org/10.1016/j.scitotenv.2019.135630

49

Appendices

Appendix 1: Interview/questionnaires for fish farmers, fishermen and government officials

A: Interview/questionnaires for fishermen

1. For how long have you been involved in fishing?

2. What kind of fishing gear are you using?

3. Do you fish alone or employ others?

4. How much do you catch and earn from fishing per month?

5. What are the most important species of your fish catch in the past 10 years?

6. What do you think about aquaculture in Lake Victoria? Does it cause any problems for you, for

example, restricting where you can fish?

7. Have you witnessed any change in fish catches in the past 10 years? If yes, do you think

aquaculture can be the source of this change?

8. Do you ever catch the same species that they grow in the fish farms?

9. Have you noticed any species lost in recent years? If yes, list their names

10. Have you noticed any changes in the water quality of the Lake in recent years? Why do you

think this has happened?

11. What do you think could be done in order to improve future fish catches from Lake Victoria?

B: Interview/questionnaire for government officials

1. What is your role in protecting Lake Victoria?

2. Aquaculture is a growing industry in Lake Victoria; can you describe your role in regulating

and supporting the aquaculture industry?

3. Do you think cage fish farming activities can have impacts on the Lake Victoria

environment and ecosystem? If yes, what are those impacts?

4. Have you witnessed any change in fish from the Lake in the past 10 years? If yes, what

do you think can be the source of this change

50

5. Have you witnessed any environmental change in the Lake in the past 10 years? If yes,

what is that change? Why do you think this has happened?

6. Have you witnessed any species declined or lost in the past 10 years? If yes, list their

names

7. Have you witnessed any new species of fish in recent years? If yes, list their names

8. What do you think can be done to improve aquaculture management and reduce the

environmental impacts on Lake Victoria?

C: Interview/Questionnaires for fish farmers

1. How long have you been involved in cage fish farming?

2. What is the type and size (number of cages) of your fish farm? What is the fish production

capacity (in kilogram) of your farm per year?

3. How many people do you employ?

4. Why did you site your fish farm in this particular location?

5. What type of fish are you growing on your farm? Why did you choose the species?

6. Where do you get the fish spawn/juveniles for your farm?

7. What type of feed are you using on your farm? Is it from local sources or from outside the

country?

8. Where is the market for your fish?

9. Do you think your fish farm has an effect on the lake environment? If yes, can you describe

it?

10. On your fish farm, have you encountered problems with fish health or escapes?

11. Have you seen any changes in the lake fish or water quality since you started fish farming?

12. Do you have any troubles with other lake users, for example fishers, boat users?

13. What benefits does your fish farm bring to the local community? 14. How much better off

are you since you began fish farming?

14. What challenges are you facing in the development of your business?

15. What do you think can be done to improve aquaculture development in Tanzania?