environmental strategies for aquaculture

Environmental Strategies for aquaculture: Report for NEPAD PAF-AWG Page i

Partnership for African Fisheries (PAF) Aquaculture Working Group:

Environmental Strategies for Aquaculture: A Strategic review on environmental capacity and management, climate change

response/adaptation and aquatic system health.

Contributors Neil Handisyde Sophie Fridman John Bostock

Authors Contact: [email protected]

February 2014

Increasing cage culture across SS Africa putting demands on local environments, Jinja, Uganda. Photo courtesy of Iain Gatwood

Environmental Strategies for aquaculture: Report for NEPAD PAF-AWG Page ii

Acknowledgements This report was commissioned by NEPAD through the University of Stirling UK. Thanks are due to Mr. John Bostock and William Leschen for contributions to editing. Disclaimer The information and views set out in this report are those of the author and do not necessarily reflect the official opinion of NEPAD or the University of Stirling. Neither NEPAD, the University of Stirling, nor any person acting on their behalf may be held responsible for the use which may be made of the information contained therein.

Environmental Strategies for aquaculture: Report for NEPAD PAF-AWG Page iii

Contents CONTENTS ................................................................................................................................... II

EXECUTIVE SUMMARY ................................................................................................................. V

1 INTRODUCTION .................................................................................................................... 1

1.1 INTRODUCTION ........................................................................................................................... 1 1.2 AQUACULTURE/ENVIRONMENTAL INTERACTIONS .............................................................................. 1 1.3 SUB-SAHARAN AFRICA; REGIONAL RESOURCES AND FEATURES ............................................................ 2 1.4 AQUACULTURE; ENVIRONMENT AND SPECIES .................................................................................... 3 1.5 CURRENT AND EMERGING TOPICS ................................................................................................... 5

2 ENVIRONMENTAL CAPACITY AND MANAGEMENT ................................................................. 7

2.1 INTRODUCTION ........................................................................................................................... 7 2.2 ENVIRONMENTAL INTERACTIONS WITH AQUACULTURE SYSTEMS .......................................................... 7

2.2.1 Introduction ..................................................................................................................... 7 2.2.2 Land and water requirements ......................................................................................... 8 2.2.3 Sedimentation, effluent discharge, nutrient enrichment and eutrophication ................ 9 2.2.4 Chemical residues ............................................................................................................ 9 2.2.5 Inputs for aquaculture ..................................................................................................... 9 2.2.6 Impacts on wild populations and ecosystems due to escapes and disease .................. 10 2.2.7 Other impacts ................................................................................................................ 10

2.3 REVIEW OF ISSUES AND CURRENT THINKING ABOUT AQUACULTURE AND ENVIRONMENTAL CAPACITY IN INLAND AND COASTAL SYSTEMS. ............................................................................................................... 11 2.4 MANAGEMENT APPROACHES ....................................................................................................... 14 2.5 DEFINING, MONITORING, AND MODELLING ENVIRONMENTAL IMPACTS AND CARRYING CAPACITY .............. 2 2.6 SUMMARY .................................................................................................................................. 4

3 THE CONCEPT AND PRACTICALITIES OF AQUATIC SYSTEM HEALTH WITH RESPECT TO AQUACULTURE PRODUCTION ....................................................................................................... 6

3.1 AQUATIC ECOSYSTEM HEALTH ........................................................................................................ 6 3.2 AQUACULTURE PRODUCTION SYSTEMS AND ENVIRONMENTS ............................................................... 7

3.2.1 Freshwater ...................................................................................................................... 7 3.2.2 Coastal i.e. marine and brackish water ........................................................................... 7 3.2.3 Recirculated aquaculture systems (RAS) ......................................................................... 8

3.3 RISKS AND THEIR MANAGEMENT .................................................................................................. 10 3.3.1 Ecosystem function and biodiversity ............................................................................. 10 3.3.2 Fish health ..................................................................................................................... 13

4 CLIMATE CHANGE AND AFRICAN AQUACULTURE ................................................................. 17

4.1 INTRODUCTION ......................................................................................................................... 17 4.2 THE ABILITY TO PREDICT CLIMATE CHANGE ..................................................................................... 17 4.3 PREDICTED CLIMATE CHANGES FOR AFRICA .................................................................................... 19

4.3.1 Temperature.................................................................................................................. 19 4.3.2 Rainfall .......................................................................................................................... 20 4.3.3 Extreme weather ........................................................................................................... 21 4.3.4 Sea level rise .................................................................................................................. 22

Environmental Strategies for aquaculture: Report for NEPAD PAF-AWG Page iv

4.4 POTENTIAL IMPACTS OF CLIMATE CHANGES ON AFRICAN AQUACULTURE ............................................. 23 4.4.1 Introduction ................................................................................................................... 23 4.4.2 Temperature changes ................................................................................................... 25 4.4.3 Water availability changes............................................................................................ 26 4.4.4 Sea level rise .................................................................................................................. 28 4.4.5 Effects of extreme weather ........................................................................................... 29 4.4.6 Ocean acidification ........................................................................................................ 29 4.4.7 Indirect impacts ............................................................................................................. 30

4.5 ASSESSING VULNERABILITY ADAPTATION ....................................................................................... 30

5 DEVELOPING A SUSTAINABLE AND RESILIENT APPROACH TO AQUACULTURE DEVELOPMENT ... .......................................................................................................................................... 32

5.1 INTRODUCTION ......................................................................................................................... 32 5.2 ENVIRONMENTAL CONTEXT FOR AQUACULTURE GROWTH IN AFRICA .................................................. 32 5.3 FISH HEALTH AND WELFARE ISSUES AND MITIGATION MECHANISMS ................................................... 34 5.4 CLIMATE CHANGE AND RESPONSES ............................................................................................... 35 5.5 PRIORITISING DEVELOPMENTS IN AQUACULTURE IN SSA................................................................... 38

6 RECOMMENDATIONS ......................................................................................................... 40

6.1 INTRODUCTION ......................................................................................................................... 40 6.2 POLICY PRIORITIES ..................................................................................................................... 40

6.2.1 Land and water ............................................................................................................. 40 6.2.2 Seed supply .................................................................................................................... 41 6.2.3 Feed and fertilisers ........................................................................................................ 42 6.2.4 Aquatic system health ................................................................................................... 42 6.2.5 Climate change and resilience ...................................................................................... 43

6.3 INTEGRATING POLICIES ............................................................................................................... 43 6.4 STRATEGIC ROLES ...................................................................................................................... 45

6.4.1 Private Enterprises ........................................................................................................ 45 6.4.2 NGOs ............................................................................................................................. 46 6.4.3 Governments/Public Sector Agents ............................................................................... 47

REFERENCES .............................................................................................................................. 48

ANNEX 1 .................................................................................................................................... 56

Environmental Strategies for aquaculture: Report for NEPAD PAF-AWG Page v

Executive summary It is well established that the world population is increasing as is the demand for aquatic food products. For almost three decades fishing techniques have left the fisheries stocks from oceans, lakes and rivers depleted. Aquaculture, in common with other agricultural sectors, uses natural resources and interacts with the environment and it is now universally accepted that increasing efficiency in resource use and minimising adverse environmental interactions are major goals for the future. If, therefore, the sector is expected to expand as a response to the growing demand for fish, there are, inevitably, a number of constraints limiting the expansion of aquaculture and questioning its long-term sustainability. These broader issues concerning the interaction of aquacultural operations with the environment may include a competition for land and water resources from agricultural, industrial and domestic usage creating the potential for conflict between aquaculture and competing users especially in areas where water is limiting. The effects of discharge of effluent from aquacultural operations on the environment also pose a threat and may include both solid wastes with high carbon load and soluble wastes with their dissolved nutrients in effluent water with their compounding effects of eutrophication of surrounding ecosystems. Chemical residues discharged from aquacultural operations resulting from the use of pest and disease controlling agents, compounds used to reduce bio fouling, anaesthetics, and hormones used for inducing breeding or sex reversal also impact their surrounding environment. In addition, the ecological impact of escaped stock on local aquatic systems, especially when non-native species are farmed, is significant and the introduction or increased prevalence of diseases resulting from aquacultural activity similarly may show detrimental effects on the local fish stock and environment. The need for higher quality feed inputs for intensive aquaculture operations raises further questions such as the use of capture fisheries as a protein source or the cultivation (and associated land and water use) for grain and oilseed ingredients. Additional challenges are posed by the threat of climate change and the need for resilience. Further research is needed to better understand the interactions and importance of each effect. However, there is a growing appreciation that food production activities need to be better integrated to make more effective use of ecosystem services and to provide better complementarily at different ecological scales. In particular there is a need to match the waste outputs from one process with the input needs of others, to minimise transport of intermediate products and to promote appropriate system types according to the development of markets and infrastructures. There is a growing body of work that defines the environmental impacts of aquaculture and hence provides guidance on appropriate mitigation measures and increasingly accepted guidelines and standards for operation and management. There is rather less work on aquaculture at the ecosystem level and its interaction with other activities, but further international collaboration will build on this. Strategic guidelines are increasingly in place to guide policy and government activity. Voluntary standards and codes of practice are also available to producers to help improve management practices and to guide future development. The main issues are probably developing capacity, both in terms of expertise and facilities to undertake proper assessments and monitoring, and the strength of governance to ensure that development is carried out responsibly. A greater appreciation of aquatic ecosystem health issues are also needed throughout industry and society, requiring promotion through education, NGO and marketing activities.

Environmental Strategies for aquaculture: Report for NEPAD PAF-AWG Page 1

1 Introduction

1.1 Introduction

It is well established that the world population is increasing as is the demand for aquatic food products. For almost three decades fishing techniques have left the fisheries stocks from oceans, lakes and rivers depleted. Guidelines often exist, however alleged breaches of regulation and inadequacies in policy implementation have resulted in an over-exploitation of stock. This has had apparent negative implications for food security through the reduction of social welfare in countries around the world, especially in developing countries relying on fish as their main source of animal protein and income from subsistence fisheries. Hand in hand with this decline a concomitant increase in aquaculture derived foods has resulted in the formation of a globally important and dynamic industry.

Aquaculture has been defined by the FAO (1990) as the farming of aquatic organisms including fish, molluscs, crustaceans and aquatic plants and implies some kind of intervention in the rearing process in order to enhance production e.g. regular stocking, feeding, protection from predators etc. It is universally recognized that it can bridge this gap between declining capture fisheries output and the rapidly increasing global demand for seafood. For several decades aquaculture has been the fastest growing food production sector in the world, and worldwide production has been seen to grow at an average annual rate of 8.1% since 1981. With poultry showing the next largest rate of increase over this period at 5%, the global importance and vitality of the aquaculture industry clearly stands out (FAO, 2008a). Indeed aquaculture production, excluding aquatic plants, has shown an increase from c. 600 000 tonnes (t) in 1950 to 52.5 million t in 2008, accounting for around half of fisheries products for human consumption (FAO, 2010b).

In 2009 Africas population passed 1 billion and with an estimated growth of 24 million a year, it is expected to double by 2050. In sub-Saharan Africa (SSA) most commercial and artisanal capture fisheries are either declining or are optimally exploited (FAO, 2005) and per capita fish consumption has similarly been seen to decrease. This can only realistically be replaced with aquaculture-derived products; in order to maintain the current per capita fish supply in SSA of 6.6 kg/person/year, a 20 % increase in production within 10 years and a 32 % increase by the year 2020 is required (Delgado et al., 2003; NEPAD, 2005). Therefore, combined with the high population growth rate, this shortfall of fish emphasises the need for a rapid growth of the aquaculture sector. Availability of land in sub-Saharan Africa in not a constraint for aquaculture development (Kapetsky, 1994) therefore the potential clearly exists to significantly increase aquaculture production using existing bio-physical resources (Aguilar-Manjarrez and Nath, 1998).

1.2 Aquaculture/environmental interactions

Aquaculture, in common with other agricultural sectors, uses natural resources and interacts with the environment and it is now universally accepted that increasing efficiency in resource use and


minimising adverse environmental interactions are major goals for the future. If, therefore, the sector is expected to expand as a response to the growing demand for fish, there are, inevitably, a number of constraints limiting the expansion of aquaculture and questioning its long-term sustainability. These broader issues concerning the interaction of aquacultural operations with the environment may include a competition for land and water resources from agricultural, industrial and domestic usage creating the potential for conflict between aquaculture and competing users especially in areas where water is limiting. Whilst cage aquaculture, especially in a marine environment, can be viewed as efficient in terms of water use when compared to other agriculture sectors, the growth of freshwater, land based aquacultural facilities may be restricted if seen to compete with other users.

The effects of discharge of effluent from aquacultural operations on the environment also pose a threat and may include both solid wastes with high carbon load and soluble wastes with their dissolved nutrients in effluent water with their compounding effects of eutrophication of surrounding ecosystems. The impact of these effects depend largely on the scale of the aquaculture facilities and may range from a relatively low discharge from extensive pond based operations to a higher discharge from intensive systems with higher rates of water exchange, higher stocking densities, and large inputs of feeds entering receiving waters (Pillay, 2004). Chemical residues discharged from aquacultural operations resulting from the use of pest and disease controlling agents, compounds used to reduce bio fouling, anaesthetics, and hormones used for inducing breeding or sex reversal also impact their surrounding environment. In addition, the ecological impact of escaped stock on local aquatic systems, especially when non-native species are farmed, is significant and the introduction or increased prevalence of diseases resulting from aquacultural activity similarly may show detrimental effects on the local fish stock and environment.

1.3 Sub-Saharan Africa; regional resources and features

The contribution of sub-Saharan Africa to global aquaculture production remains very small but is increasing significantly; between 2000 and 2008 there was an increase in production from 55 802 to 238 877 tonnes (Table 1). Nigeria is consistently the largest producer of aquaculture products in sub-Saharan Africa; in 2008 it accounted for 60 % of production by quantity (Table 1 and Figure 1) at 56% of the total value. Other major producers are Uganda and Madagascar and these three countries together contributed 86 % of the total production in SSA in 2008 (the first seven major producers account for 93.7 % of total production in 2008 by quantity (Table 1)).


Table 1: Top seven aquaculture producers in sub-Saharan Africa (2000 and 2008) by quantity (in tonnes) and by value (US$ '000). Source - FAO, 2010b

Country 2000 2008 (tonnes) (US$ 1 000) (tonnes) (US$ 1 000)

Nigeria 25 718 56 630 143 207 374 700

Uganda 820 820 52 250 118 770

Madagascar 7 280 14 773 9 581 41 014

Zambia 4 240 27 720 5 640 39 566

Ghana 5 000 9 404 5 594 19 555

Kenya 512 6 996 4 452 16 313

South Africa 2 807 1 026 3 215 13 354

Other 9 425 22 333 14 938 42 047

Total 55 802 139 701 238 877 665 389

Figure 1: Major aquaculture producers by quantity (%) in sub-Saharan Africa (2008).

1.4 Aquaculture; environment and species

It has been reported that about 30% of the land area in Africa is suitable for small-scale fish farming and only 3.8% of Africas surface and groundwater is harnessed (Anguilar-Manjarrez and Nath 1998; Kapetsky, 1995). It can be seen that existing aquaculture production in SSA predominates in freshwater environments (Table 2). Whilst the National Aquaculture Sector Overview (NASO) data shows that over 45 freshwater and brackish water fish species are used in African farms, however

Nigeria 60%

Uganda 22%

Madagascar 4%

Zambia 3%

Ghana 2%

Kenya 2%

South Africa 1%

Other 6%


the tilapias, catfishes and the cyprinids were the main contributors to production (Table 3) accounting for over 92% of total production from fresh and brackish water. Indeed in 2008, catfish contributed about 52% of the total production and interest in the culture of the species, for domestic markets, intra- and interregional trade and exports overseas is still growing in several countries.

Table 2: Aquaculture production in quantity (in tonnes) and value (US$ 1 000) by environment (2008). Source: FAO, 2010b

2008

Quantity in tonnes Value in tonnes (US$ 1 000)

Freshwater 228 753 586 138

Brackish water 154 633

Marine 9 970 78 618

Total 238 877 665 389

Table 3: Production (in tonnes) for three major aquaculture species in sub-Saharan Africa (2008). Source: FAO, 2010b. Symbols: nei = not elsewhere included

Cultured species 2008 North African catfish 76 601 Torpedo shaped catfishes nei 46 687 Nile tilapia 33170 Cyprinids nei 15 669 Tilapias nei. 10 352 Nile perch 8 584

Mariculture currently contributes only 2 % of the total production quantity and 5 % of the total value. Fourteen marine species are currently listed as aquaculture species and the main species for which production figures are available are listed below (Table 4). The most important producers of seaweeds (over 1 000 tonnes in 2008) are Madagascar, South Africa and Zanzibar.

Table 4: Mariculture production by species in SSA (quantity and value) (2003 and 2008).

2003 2008

Quantity (tonnes)

Value US$ 1 000 quantity value

Giant Tiger Prawn 8 257 45 915 7 340 37 792

Perlemoen abalone 515 18 465 1040 35 443

Mediterranean mussel 623 415 726 640

Red drum 213 1205 256 196

Pacific cupped oyster 289 904 236 889

Mediterranean mussel 623 415 726 640


1.5 Current and emerging topics

Many parts of SSA are facing freshwater shortage and an increased trend towards intensification and diversification are emerging in SSA aquaculture. Integrated aquaculture including rice-based aquaculture systems is presently practised in a few countries, but has great potential at the rural, small-scale farmer level to contribute towards sustainable livelihoods by strengthening the ability of farmers to respond to improve their resilience as well as increasing food security. Mariculture is an emerging and promising sub-sector, and, in addition, farmers from inland areas are looking for more efficient ways to increase production at reduced costs, to reduce growing time and also to culture more value species e.g. freshwater prawn farms in Madagascar are intensifying their production techniques and in both Madagascar and Mozambique operators are ensuring at the same time strict environmental controls. Similarly cage culture in freshwater lakes and reservoirs are continuing to expand in several countries e.g. Nigeria, Ghana, Cte dIvoire, Cameroon, Uganda, Zambia, Malawi, Kenya, Madagascar and interest has been heightened following the organization of a regional workshop on the subject in Entebbe, Uganda, in 2004 (Halwart and Moehl, 2008). Malawi and Zambia have zoned areas for lacustrine cage culture (Hecht et al., 2006). Further research on the production of tilapia in cages (Ofori et al., 2009) has been undertaken in Ghana.

Hand in hand with these initiatives, the emergence of private sector-led small- and medium-size enterprises (SMEs) and the expansion of larger commercial ventures, stimulated in some cases by growing public support and the inflow of foreign capital and expertise. International awareness and interest in aquaculture spawned by the New Partnership for Africas Development (NEPAD) Fish for All Summit in 2005and the implementation of FAOs Special Programme for Aquaculture Development in Africa (SPADA) has also contributed to this development. The management practices of some of these undertakings are vertically integrated, environmentally responsible and socially acceptable. The operations adhere to standard sanitary operation processes and the entrepreneurs are adopting strategies to safeguard producers and consumers. Products from some of the enterprises are subject to labelling and certification. The successful cage culture initiative in Lake Kariba, Zimbabwe, is summarized in Box 1.

Box 1: Lake Harvest Cage Culture on Lake Kariba - A model of large-scale aquaculture initiative in

Africa.

Lake Harvest Ltd. located in the Zimbabwean waters of Lake Kariba was established in 1997 and is one of the single, largest aquaculture businesses currently operating in the region. The farm consists of a 10 hectare pond-based hatchery unit which supplies seed to six cage sites, each with 14 cages and capable of producing 800 tonnes/site/year. Nile tilapia are grown to 750 g and processed in a EU-standard plant with a capacity of 15 tonnes of whole fish/day. The initial target market was Europe, but local and sub-regional consumers currently account for the majority of production. This farm can be seen as a model for economic viability of large-scale aqua-business in Africa and although enterprises of this size require major investments, they can be scaled down.


Several SSA governments are recognizing the importance of state roles in facilitating and coordinating aquaculture activities, adopting aquaculture specific policies and developing framework strategies that attempt to provide a roadmap to guide development. A few governments have provided soft credit lines in agricultural development and commercial banks but more often than not, access to credit, with interest rates of 25 to 40%, the perpetual problem of seed and feed of sufficient quantity and quality, coupled with land ownership or secure access to common property resources, prove major constraints to the expansion and/or intensification of aquaculture production. The characterization of species, selective breeding programmes and the production of low-cost diets are the focus of research in a few centres. In the target countries, under the auspices of SPADA, on-farm participation in research using model farms and private enterprises is resulting in rapid diffusion of technologies through farmer-to-farmer pathway. Generally, extension services are weak and inadequately resourced there is an urgent need to improve the individual services and also strengthen the links between research and development.

To conclude, the development of the aquaculture sector in SSA will obviously face challenges such as meeting the growing demand for capital, developing and maintaining both quantity and quality of seed and feeds, strengthening the base for aquaculture management and facing the challenges of increasingly severe competition for resources such as land and water. However, an increased private sector involvement in the production and delivery of inputs e.g. seed and feed, the manufacture and supply of aquaculture equipment in some countries and the emergence of producer associations at both national and local level all play an important role in the development of the sector and could suggest that the increase in production that has been witnessed in recent years is set to continue.


2 Environmental capacity and management

2.1 Introduction Globally the aquaculture sector continues to show significant growth (FAO, 2010a). This trend holds true for Africa where annual growth for the continent as a whole based on recorded production statistics for aquatic animal species has averaged approximately 11.4% for the 2000 to 2008 period (FAO, 2010b). Despite this growth aquaculture production in much of Africa is relatively low when compared with many Asian countries and there would appear to be considerable potential for further development. Globally there is an Increasing awareness, and demand for, sustainable development. As aquaculture has intensified it has attracted increased attention in terms of environmental concerns (Pillay, 2004). Minimizing ecological impacts is often seen as posing a conflict of interest in relation to demands for rapid economic development, increasing food demands and growing populations. This situation may be especially true in developing countries where demand for improvement in living standards may be high (Pillay, 2004). Ultimately unsustainable consumption of biophysical resources by aquaculture will impact on productivity and increase resource competition with other sectors (Hall et al., 2011). Understanding how aquaculture interacts with the environment in which it operates should be seen as important in allowing aquaculture to develop sustainably with minimal environmental impact while also meeting the environmental needs of aquaculture itself. With this in mind issues of site selection, production methods and scale of production become relevant in relation to carrying capacity which can be defined as the level of resource use both by humans or animals that can be sustained over the long term by the natural regenerative power of the environment (Ross et al. 2011).

2.2 Environmental interactions with aquaculture systems

2.2.1 Introduction In common with all forms of food production, and human activity in general, there will always be some form of interaction between aquaculture and the environment. Aquaculture interactions with the environment are a two way process and while aquaculture has the ability to modify the environment, the environmental its self plays a crucial role in supporting aquaculture. The ways in which these interactions take place are often complex and while it is possible to make some generalisations many issues will need to be viewed on a case by case basis. Peoples views on how aquaculture and the environment affect each other are likely to be influenced by their role in relation to aquaculture. For example environmental regulators often focus on waste outputs from aquaculture facilities while others may focus more on competition for resources such as land and water. Aquaculturists themselves are likely to be concerned with factors


that directly influence production such as availability of suitable areas for production, water availability and quality, temperature and resources for inputs such as feeds.

2.2.2 Land and water requirements Perhaps the most obvious requirements for aquaculture are space in which to operate and a supply of water. As the human population increases so does the requirement for fresh water for a range of agricultural, industrial and domestic uses. This creates the potential for conflict between aquaculture and competing users, especially in areas where the availability of water is limited. Marine aquaculture can be viewed as very efficient in terms of freshwater use when compared to other agriculture sectors especially in terms of producing animal protein. Cage culture in inland systems such as the large lakes in Africa may also be viewed as neutral in terms of freshwater use provided the quality of the water is not adversely affected. Egypt is a water scarce country (less than 1000m3 of freshwater per capita per year) with a growing population. Egypt is also Africas largest aquaculture producer, with the majority of production taking place in extensive or semi intensive earthen ponds, and provides a good example of conflicts over water use that are highly significant for the aquaculture sector. Sherif (2011) notes how the Nile supplies 97% of Egypts renewable water and that how this limited water supply in turn limits food production. Only marine and brackish water, water from lakes and an agricultural drainage, and infertile land is allowed to be used for aquaculture production with the use of freshwater suitable for irrigation is prohibited (Sherif, 2011). Sherif (2011) also suggests that plans to improve irrigation systems in some areas of Egypt will result in reduced quantities of increasingly saline water being available for aquaculture affecting both species composition and production capacity. Water quality issues have also affected cage culture in Egypts Nile River with many areas becoming unsuitable for due to pollution of the water by inorganic nitrogen, organic substances, phosphorus, and heavy metals (Sherif, 2011). Egypt has seen an increase in intensive aquaculture production in desert areas that makes use of ground water as well as agricultural drainage with a range of salinities. Most of the farms operate flow through systems and are associated with agriculture where discharged water can be used for producing crops and livestock. Sherif, (2011) suggests that even if agricultural production from such schemes is relatively low they may still be viable as there is minimal competition in terms of other potential uses of the land. It is also suggested that the waste water from aquaculture can be of benefit to agriculture due to the enhanced nutrient content and that aquaculture can be viewed as highly efficient in this context as it only uses the water rather and consuming it. The fact that land based aquaculture needs a supply of water means that floodplains and wetlands are often chosen for aquaculture sites (Pillay, 2004). Issues associated coastal wetlands such as salt marshes and mangroves being converted into aquaculture ponds for species such as shrimp have received considerable attention. Coastal wetland systems are often highly productive acting as nursery and feeding grounds for a range of commercially significant fish and shellfish species while also playing a significant role in nutrient cycling (Pillay, 2004). Madagascar is Africas largest producer of shrimp. A study looking at change in mangrove forest cover in Madagascar between 1975 and 2005 found that overall loss of mangroves during that period was around 7% which is lower than many other parts of the world. Aquaculture accounted for a relatively small proportion of


mangrove deforestation (3%) when compared with factors such as agriculture (36%) and logging (16%) (Giri & Muhlhausen, 2008).

2.2.3 Sedimentation, effluent discharge, nutrient enrichment and eutrophication Pond based farms operating at low to moderate intensities may only discharge water periodically such as before the harvesting of stock. Seeing that water quality in such farms has to be maintained at a reasonable level for successful stock production, and much detritus that collects at the bottom of the pond is removed manual whilst the pond is being prepared for new stock, the impacts of infrequent discharge of water from such facilities may be quite small (Pillay, 2004). Pillay (2004) goes on to discuss how for more intensive systems such as ponds, tanks and raceways with higher rates of water exchange, higher stocking densities, and large inputs of feeds the situation can be very different with significant quantities of solid and soluble wastes entering receiving waters. Cage based aquaculture is typically highly intensive with waste products directly discharged into the surrounding water body. In areas such as enclosed bays the rate of water exchange driven by currents becomes significant and needs to be adequate for the quantity of aquaculture involved it water quality in the area is to be maintained. Solid wastes tend to settle under or in the vicinity of the cage with the degree of dispersion being influence by water depth and current velocity (Beveridge, 2004). Solid waste outputs from aquaculture largely consist of organic carbon with impacts on receiving waters often being quantified, and in some cases regulated, in terms of biochemical oxygen demand (BOD) (Pillay, 2004). Nitrogen and phosphorous compounds represent the soluble wastes of most concern with increasing concentrations of dissolved nutrients in receiving waters being termed hypernutrification. In areas where primary productivity of phytoplankton and aquatic plants is nutrient limited then hypernutrification can lead to increases in primary productivity (eutrophication) and ultimately potential ecosystem changes (Pillay, 2004).

2.2.4 Chemical residues Chemical residues discharged from aquaculture facilities typically result from the use of pest and disease controlling agents, compounds used to reduce bio fouling, anaesthetics, and hormones used for inducing breeding or sex reversal. Alternatively aquaculture its self may be affected by chemical residues from external sources such as those used in agriculture to control pests and diseases in crops, or as result of industrial and domestic use (pillay, 2004).

2.2.5 Inputs for aquaculture Aquaculture, especially in its more intensive forms, requires a range of inputs such as energy and feeds that may have consequences for, or be affected by, the environment. Formulation of aquaculture feeds for carnivorous finfish and shrimp tends to be associated with the use of fishmeal and fish oil while in other cases wild fish is fed more directly to cultured species. The practice of using wild fish stocks to feed farmed fish has been questioned in terms of impacts on wild stocks and the efficient use of food resource (i.e. wild fish that could be used for direct human consumption being turned in to aquaculture feeds). The implications for the poor and undernourished of using wild fish in aquaculture feeds is reviewed by Wijkstrm (2009) who suggests that in a number of Asian countries the impacts of using wild fish as feed are significant, providing livelihood


opportunities for some, while reducing potential food supply for others. However the author goes on to point out that for Africa the situation is somewhat different and the use of fish for feed is largely insignificant at the current time due to feed fisheries being uncommon and minimal use of fish as feed for what is still a relatively small and emerging aquaculture industry in most areas of the continent. It is perhaps worth considering how this situation may change if African regions start to see a significant growth and intensification of the aquaculture sector (e.g. the increased exploitation of small pelagic fish such as Rastrineobola argentea in Lake Victoria for aquafeed).

2.2.6 Impacts on wild populations and ecosystems due to escapes and disease Escapes from aquaculture facilities result from human error along with events such as flooding of ponds and failure of fish cages with the result of potentially large numbers of individuals entering the local aquatic systems. The ecological impacts of such releases are likely to be most significant in cases where non-native species are being cultured. The tendency for a non-native species to become invasive will depend on the species in question as well as the ecology and environmental variables of the aquatic system into which it is introduced. In areas where native species are being cultured there may still be concerns over escapes due to the fact that many cultured species have undergone significant selective breeding and thus may be genetically dissimilar and less diverse when compared to wild populations. Along with ecological effects due to competition and predation by escaped stock there is the potential for aquaculture activities to impact on wild population via the introduction of, or increased prevalence of disease. For example in Scotland cage culture Atlantic salmon in areas such as the UK and Norway has blamed for an increase in prevalence of fish lice in wild stocks (e.g. Hansen & Windsor, 2006).

2.2.7 Other impacts Visual impacts of aquaculture facilities are a significant issue in some parts of the world where they are seen to impact on the scenic value of water front areas and may need to be evaluated as part of an environmental impact assessment (EIA). In such cases conflicts of interest may occur between those involved with aquaculture, local residents, and those whose livelihoods are linked with tourism. Interactions between aquaculture and birds or aquatic mammals are generally not well researched although there may be negative impacts on some species due disturbance and anti-predator measures adopted by farmers (Pillay, 2004). That said there are also examples of positive impacts as a result of habitat modification such as increased perching and feeding sites for sea birds (Roycroft, Kelly & Lewis, 2006). There may also be some ecological effects due to the attraction of predator species to aquaculture sites and thus concentration of predator numbers in a localised area (Buschmann, 2009). There is the potential human health issues associated with aquaculture and the environment. Poorly managed aquaculture facilities may lead to an increase in the transmission of water-borne disease while on the other hand stocking of fish into waters such as in the case of integrated aquaculture agriculture systems may reduce numbers of potentially disease carrying mosquitoes. Sapkota et al. (2008) reviewed current knowledge of human health risks related to aquaculture and highlighted the potential for increased levels of antibiotic residues, agro-chemicals, heavy metals, antibiotic resistant bacteria, parasites and viruses in aquaculture products. Sapkota et al. (2008) also suggests


that individuals working with, or living in close proximity to, aquaculture may be at greatest risk. It is also possible that risks may be greater in some developing countries where the use of various agents may not be as tightly controlled. However it should be noted that Sapkota et al. (2008) state that additional research is needed to understand health risks associated with aquaculture and develop measures to reduce risks that may be found.

2.3 Review of issues and current thinking about aquaculture and environmental capacity in inland and coastal systems.

While aquaculture development and its environmental consequences are viewed and regulated differently in different regions, there is an increasing general acceptance that future aquaculture development should be conducted in a more considered and sustainable way. In 2006 the Fisheries and Aquaculture Department of the Food and Agriculture Organization (FAO) of the United Nations started to develop an ecosystem approach to aquaculture EAA which was defined by Soto et al., (2008) as a strategic approach to development and management of the sector aiming to integrate aquaculture within the wider ecosystem such that it promotes sustainability of interlinked social-ecological systems. The EAA represents a common framework for sustainable aquaculture development and has three main principles which have been defined by Soto et al., (2008) as; 1) Aquaculture development and management should take account of the full range of ecosystem functions and services, and should not threaten the sustained delivery of these to society, 2) Aquaculture should improve human well-being and equity for all relevant stakeholders and 3) Aquaculture should be developed in the context of other sectors, policies and goals. When considering the principles of an EEA, and environmental impacts in general, the question of scale becomes important i.e. farm scale, waterbody/watershed scale, and global scale (Soto et al., 2008). It has been suggested that there should be a move away from assessment and regulation on a site by site basis with more focus on assessment at varied scales where issues such as cumulative effects of multiple aquaculture operations along with other activities may be significant within a region (Bermudez, 2011). This said assessment at the farm scale is still important, for example issues relating to escapes and disease operate and are best managed at this scale (Soto et al., 2008). Table 5 gives examples of potential positive and negatives impacts of aquaculture at the farm, watershed and global scales.

Table 5: Examples of potential positive and negative impacts of aquaculture at the farm, watershed, and global scales. Adapted from: FAO (2010c)

Issues at different scales Farm Watershed Global

INPUTS Collection of seed from the wild

+ effects on local communities that rely on this fishery

- effects on wild stocks

Production of seed + culture-based fisheries + restocking threatened species



Collection of feed (e.g. trashfish)

+ effects on local communities that live on this fishery

- effects on wild stocks used as feed (e.g. trashfish)

Production of feed (e.g. pellets)

+ livelihoods in countries that provide fishmeal and fish oil

- effects on pelagic stocks used to produce fishmeal/ oil

Production of local feeds

+ diminishing production costs + increased integration to other sectors

+ increased livelihood opportunities and diversification

Labour + livelihoods and job opportunities

- unfair wages

+ livelihoods and job opportunities

- lack of social security - lack of natural calamity

insurance

Infrastructure - impacts of large construction in large farms

+ roads and communications development by private sector

- competition with fisheries for jetty, port infrastructure

RESOURCE USE Water - use of water surface

area - reduces wild fishery

area - hampers navigation

- competing with other sectors for use of freshwater

Land/coastal habitats

- conversion of sensitive habitats for aquaculture use in large farms (mangroves, wetlands)

- conversion of sensitive habitats for aquaculture use (mangroves, wetlands)

- competition for coastal resources

- conversion of rice fields and other agricultural land to fish ponds

Energy - use of energy for pumping water and aerators

- use of fuels for transport of product to local market

- use of fuels for cold chain and transport of product to local market

OUTPUTS Biomass + biomass production

for hunger alleviation and food security

+ biomass production for hunger alleviation and food security

+ biomass production for food security

- negative impact on fisheries through competition for common markets

Income + provision of alternative livelihoods and jobs

+ opportunities for family labour

- unfair distribution of

incomes

+ provision of alternative livelihoods and job opportunities (direct and indirect)

+ opportunities for women and other minorities

- unfair distribution of incomes and benefits



Seed + supply to other on-growing farms

+ restocking of waterbodies (culture- based fisheries)

Nutrients + extractive species such as molluscs and seaweed reduce nutrient loading

- anoxic sediments below cages and in ponds - add to nutrient loading

close to farm (fed species)

+ provides additional nutrients for increased primary productivity

- impact on sensitive habitats (corals, seagrasses, etc.)

- add to eutrophication pressures

Escapees - economic loss to the farm

+ potential for additional wild fisheries

- potential carriers of disease - potential to change genetics of

local strains

- spread of exotic species

Diseases - economic loss to the farm

- escapees potential carriers of disease for wild fish

- spread of exotic diseases

Chemicals - potential to impact local fauna and flora

In common with other forms of food production there is always going to be some degree of environmental impact resulting from aquaculture meaning the issue becomes one of what is an acceptable level of impact for any given circumstance? Perceptions of what constitutes a reasonable level of impact will vary considerably between regions and situations. A common concern is the current state of the wider ecosystem in which aquaculture is to take place. This wider ecosystem can range from more or less undeveloped to heavily modified which in turn is likely to influence societal perceptions of what is an acceptable level of further modification. Opinions over the modification of aquatic ecosystems by aquaculture will often contrast greatly with those relating to terrestrial agriculture where heavily modified landscapes and ecosystems are generally viewed as the norm (Soto et al., 2008). In order to implement an EEA there is a need to understand the carrying capacity of the environment i.e. its ability to support aquaculture and other activities without being unacceptably affected. Current views and knowledge relating to carrying capacity and how they relate to the EAA have been thoroughly reviewed by Ross et al. (2011). Ross et al. (2011) define carrying capacity as; the level of resource use both by humans or animals that can be sustained over the long term by the natural regenerative power of the environment, while suggesting this is complementary to assimilative capacity; the ability of an area to maintain a healthy environment and accommodate wastes, and to environmental capacity; the ability of the environment to accommodate a particular activity or rate of activity without unacceptable impact. Ross et al. (2011) go on to describe how the concept of carrying capacity has been developed into a four component approach (physical, production, ecological, and social carrying capacity) in line with definitions described by Inglis, Hayden & Ross (2000) and McKindsey et al., (2006) for bivalve culture and applied to finfish culture by Geek & Legovi (2010). Definitions provided by Ross et al. (2011) for the four components of carrying capacity are given in Box 2. Ross et al., (2011) note that a hierarchical structure has been suggested by McKindsey et al. (2006) for the application of the


different components of carrying capacity with the initial stage involving the determination of physical carrying capacity followed by the modelling of production capacity. Next further modelling would be undertaken to provide estimates of ecological carrying capacity under a range of increasingly large production scenarios. The final step would introduce social carrying capacity with the aim of evaluating the potential scenarios based on the predicted outcomes from the modelling of physical, production and ecological capacity in order to make decisions about what constitutes an acceptable level of production when multiple interests are considered.

Application of the EAA principles will vary between world regions making it unrealistic to set a global set of standards for limits and thresholds. Ross et al., (2011) suggest that this problem may be approached by combining the principles of the EAA with those of carrying capacity in a way that allows the four components of adaptive capacity to be weighted with different levels of significance depending on the area and aquaculture systems in question. For example in the case of feed based intensive cage aquaculture in areas such as the European Union and United States of America there is a greater significance placed on the ecological effects of waste outputs whereas in some southeast Asian regions and China there has been a greater focus on production capacity.

2.4 Management approaches The EAA provides a framework by which to conceptualise the issues of environmental impacts and sustainable development, but in order to be applied there is a need for quantification of impacts and carrying capacities. This in turn can allow for informed policy making and strategy formation that will allow for sustainable development and management of the aquaculture sector. There are a large number of tools and approaches available to help assess environmental impacts of development activities and a range of these are evaluated in Table 6. Environmental impact assessment (EIA) is the most commonly used tool which in most instances is applied at the farm scale. FAO (2010c) discusses the use of EIA as a contributor to an EAA and suggest that small scale farms or those with low potential environmental impact should be exempt from the EIA process but for large aquaculture operations or clusters of small farms then EIA may prove useful for; decision making as to whether a project should go ahead or not, assessment of the extent and severity of environmental impacts, assessment of socio-economic impacts, means of developing environmental monitoring and/or management plans and associated mitigation measures.

Box 2. The four components of carrying capacity. Physical carrying capacity: Suitability for development of a given activity, taking account of 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 site identification, from which a subsequent more specific site selection can be made for actual development. Production carrying capacity: Estimates maximum aquaculture production and is typically considered at the farm scale. 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. Ecological carrying capacity: The magnitude of aquaculture production that can be supported without leading to significant changes to ecological processes, species, populations, or communities in the environment. Social carrying capacity: The amount of aquaculture that can be developed without adverse social impacts.


Better management practices (BMPs) and codes of practice (COP) are currently the most realistic means of reducing negative environmental impacts at the farm level, and potentially larger scales, both in terms of cost and technical practicality. BMPs can involve aspects such as site selection, feeds and feeding practices e.g. optimisation of feed conversion ratios, carful fertilisation, limiting escapes, reducing potentially harmful effluents e.g. waste water and sediment treatment or increase environmental capacity via the development of natural treatment systems, site rotation e.g. fallowing in the case of cage culture to allow time for the benthos to recover, responsible use of chemicals to control disease along with good aquatic animal and health management, facility management, and processing and transport. BMPs are commonly voluntary in nature although they typically involve input from governments in terms of policy, regulation, management and planning while at the same time needing cooperation from the aquaculture industry. (FAO, 2010c). Aquaculture management at the watershed scale differs from that of the farm scale in that there is typically greater need for responsibility to be taken by institutions, representative bodies, etc. For example in the United Kingdom the Area Management Agreements represent a framework that allows control in areas such as enclosed bays for activities including disease control, harvesting, and fallowing of cages. Using disease control as an example it is fairly easy to imagine how a coordinated response by farms that share a waterbody could be beneficial in terms of reducing costs, increasing production, and reducing environmental impacts via the most efficient use of disease controlling agents (FAO, 2010c). Perhaps one of the biggest challenges facing regulation at the watershed scale, and one that will need to be considered on a case by case basis, is that watershed or waterbody boundaries may be distinct from political ones meaning they may encompass areas belonging to different administrative regions or even countries.


Table 6: Summary of approaches to quantifying environmental impact. (Adapted from Hall et al., 2011. Original source: Bartley et al., 2007)

Method Linkages to other methods

Key attributes Strengths Weaknesses Scientific rigour Standardization of methods

Ease of application and communicability

Environmental Impact Assessment (EIA)

CBA, RA Project-based, descriptive, site-specific

Public planning and transparent process; based on multiple criteria and can be used in sensitivity analysis;identifies hazards and impacts; allows redesign of project to reduce impacts.

Does not quantify trade-offs or effects: does not provide a single performance indicator for comparisons; problems with how to interpret data

Variable (very high to low); lots of uncertainty due to lack of data; often time-constrained due to development deadlines

High (e.g. Europe) but may vary across sectors, regions and in national legislation

Good; often figures prominently in decision-making

Risk Assessment or Analysis (RA)

Should underpin all other methods for hazard identification and understanding; widely used in toxicity analysis

Tool for understanding environmental processes

Contributes to better understanding of environmental flows and impacts: attempts to be quantitative but can also be qualitative; identifies hazards and impacts.

Relies on qualitative judgements and estimates due to knowledge gaps; limited comparative use (some risks apply to some sectors, others not)

Variable at present; quantitative measures need to be developed (environmental indicators

High for procedural aspects

Good; formalized in legislation as decision-making tool

Material Flows Accounting (MFA), Mass balance, and Input/Output models (IO)

A first step towards more complete assessments using EIA, RA, energy analysis

Examines input and output of key materials; accounts for biological flows associated with economic activities; applicable to systems at many scales

Quantifies levels of inputs and outputs; can produce comparable information over time and space; used to improve ecological efficiency; well-known tool with standard protocols.

Does not reflect environmental effects; snapshot picture of flows at a specific point in time and place.

High High Very good

Energy analysis (EA) Could be incorporated into MFA and used complementarily with CBA

Examines fossil fuel energy used in food production

Produces a single measure, which is a proxy for the other components of the sector, for comparison; good history of analysis and data; comparable at all levels.

Presents an incomplete picture of the sector; relevance is questioned because energy (fuel) has a market value that will change; does not account for the environmental effects of fuel consumption.

High High Good; few decisions are made on EA alone





Human Appropriation of Net Primary Productivity (HANPP)

Can be used with MAF, EA, EF

An indicator of environmental effects based on changes in ecological flows of trophic energy caused by land use

Aggregates information into a single statistic for comparison, e.g. land use change; can examine economic causes for change; ecologically focused indicator; comparable at different scales, regions and across time

Not well developed for aquatic environments; does not describe impacts and does not address specific local ecological changes; limited expertise for HANPP analysis; in some cases analysis of secondary or tertiary productivity would be more informative

High Medium Easy to communicate; difficult to interpret

Ecological Footprint (EF)

LCA could be used as an input (aggregation of multiple units used in LCA); could also be used to present MFA results

Method to aggregate impacts into a single statistic to address eco-efficiency of human activities; converts all impacts to a measure of area needed to support a given activity

Provides a single indicator for comparison; can be applied to many levels and scales (e.g. a footprint for an individual to one for a national economy); provides accumulative/aggregated effects

Does not include all flows.Applications to food production systems are not obvious; method does not deal well with water; does not provide specific information about impacts or effects; does not address specific effects in specific environments; aggregated statistic treats all environments as homogenous and equal

Low Low Easy to communicate, but statistic is often misused or can be mis-interpreted; application is constrained by knowledge gaps on environmental differences among habitats

Life Cycle Analysis (LCA) MFA, EA, for more elaborate EIA

Examines a range of impacts of food production systems; product- oriented environmental impact assessment, with an earth-to-earth (or cradle to grave) perspective, multiple criteria analysis; quantifies potential contribution to global impacts

Allows hazards to be identified and prioritized; can build on previous work/data; can compare between products/processes/ alternatives and different scenarios; basic method to develop eco-labelling criteria to support purchasing decisions for consumers (ISO 14020 series); can provide policy-relevant insights

Large data requirements; some studies use different functional units; results address global impacts at expense of local impacts; some indicators may not be appropriate for specific cases; results are not directly applicable unless conducted for the specific comparison; some standard impact categories may not be relevant to food product systems, thus need to develop new ones

High Very high, e.g. ISO 14040-14043; streamlining LCA will reduce data requirements and facilitate comparisons; specific impact categories associated with food production not well standardized;

Can streamline LCA for specific comparisons; communication on multiple criteria may be difficult;





Cost benefit analysis, including environmental costs (CBA)

EIA, RA, EA, EFA, LCA, MFA

Uses valuation techniques, for non-marketable goods, e.g. contingent valuation, willingness to pay, hedonic pricing are techniques used in CBA to compare net result of activities of different sector

Can compare production systems; can be very inclusive of many types of information, including non-marketable goods; long history and familiarity with concept; decision-makers need and want to know this information; C/B ratio and Net Present Value provide aggregate measures of the relative performance of various production systems

Environmental values hard to determine; ecological function changes hard to predict; often environment is not included; normally long term sustainability issues not addressed; discount rates are arbitrary and may be political; loses information during aggregation

High Standardized in theory, but often not in practice

Results easily communicated and understood; including valuation of environmental goods and services and non- marketable goods makes application difficult


Private standards are becoming increasingly common in the capture fisheries and aquaculture sectors and represent a means to encourage improvements in areas such as environmental sustainability, food quality and safety. Examples of notable voluntary certification standards applicable to aquaculture are briefly detailed in here in Box 3.

Private standards and eco labelling can perhaps be seen as especially relevant in regions where there is a general perception that public regulation is insufficient. The demand for certification to private standards is mostly driven by large-scale retailers and represent a means for retailers and brand owners to pass on increasing consumer demand for ethically sourced products (Washington & Ababouch, 2011). Washington & Ababouch (2011) suggest that while developing countries remain underrepresented in terms of private standards for capture fisheries the case for aquaculture is somewhat better with proactive strategies to organise small farms into associations and self-help groups. While it has been argued that private standards represent a barrier to trade for some developing countries, it has also been suggested that most certification affects markets and species that do not form the bulk of trade for developing nations. It is also likely that in many cases where developing countries are aiming to export aquaculture products to developed areas such as Europe, then public standards for such areas may pose a greater barrier than potential private standards (Washington & Ababouch, 2011). Public regulation of aquaculture tends to be strongest in more developed countries. Examples of current policy and legislation include The European Union Water Framework, Marine Strategy Directives, the Canadian Oceans Act, and the US National Policy for the Stewardship of the Ocean, Coasts, and Great Lakes which all require spatial planning for activities such as aquaculture along with knowledge based approaches for decision making and ecosystem based approaches for integrated management (Ross et al., 2011). As part of a review of aquaculture site selection and carrying capacity for inland and coastal waters in West Africa Asmah (2011) summarises environmental regulation and suggests that all countries within the region have some form of environmental regulation and that in some cases there is potential for this to affect aquaculture. The author goes on to point out that in many cases regulation such as the use EIA is limited to large commercial farms. For example In Ghana fish farms considered to be small (no particular size defined) are only expected to register their operations with the environmental protection agency and dont need to submit an EIA report. In Nigeria only farms with an area greater than 50ha are

Box 3. Significant voluntary standards applicable to aquaculture. GLOBALG.A.P. A private sector body that sets voluntary standards around the globe to certify agricultural production processes including aquaculture. The GLOBAL G.A.P. standards functions as a global reference system for other existing standards. GLOBALG.A.P. functions as a business to business label and not directly visible to consumers. Global Aquaculture Alliance (GAA) GAA is a non-profit international trade association that aims to promote advancement in environmentally and socially responsible aquaculture. The GAA has produced a number of Best Aquaculture Practices (BAP) certification standards for aquaculture products. Aquaculture dialogues The Aquaculture Stewardship Council (ASC) is an independent non-profit organisation. The ASC was founded in 2009 by the World Wildlife Fund for Nature (WWF) and the Dutch Sustainable Trade Initiative (IDH) as a means of managing global standards for responsible aquaculture that are being developed by the Aquaculture Dialogues. The ASC aims to offer a consumer facing label that can be used by food producing companies and retailers for products that meet their standards.


expected to submit EIAs prior to commencing production. Most current farms in Nigeria are below this size and thus exempt from the EIA process (Nugent 2009).

2.5 Defining, monitoring, and modelling environmental impacts and carrying capacity

In order to set standards and control and develop aquaculture in an effective and sustainable way there is a need to be able to define acceptable levels of environmental change and monitor progress to ensure these levels are not being exceeded thus effectively working within the environments carrying capacity. Biodiversity is often associated with ecological resilience and setting limits on biodiversity impacts along with subsequent monitoring is a potential strategy for regulating environmental impact that may form part of an EIA. In reality setting limits of acceptable change is likely to be difficult due to lack of knowledge of ecological systems and associated obvious thresholds, and varying views of what constitutes acceptable change. This said in some cases defining thresholds to change may be easier. For example a given concentration of nutrients in water that results in undesirable algae blooms (FAO, 2010c). Being able to predict potential environmental change and model carrying capacity as accurately as possible thus allowing proactive rather than reactive planning and regulation should be seen as the way forward where possible and an important part of an EAA. Such approaches contribute towards informed decision making and consequently best use of resources while hopefully minimising negative environmental impacts. A large range of modelling tools are available and regulators are often drawn to the idea of models providing definitive yes or no answers or outputs in terms of exact values. In reality due to limitations in understanding, data, and resources environmental modelling rarely lives up to such expectations and is potentially much less effective when viewed and applied in such a way. In most cases the use of expert systems where modelling is used in association with expert knowledge are generally the most cost effective and practical means of decision support (McKindsey et al., 2006). Among the many challenges that face those attempting model environmental impact and carrying capacity is the choice of indicators and data. Availability and quality of data is often severely limited but in some cases it may be possible to produce proxy data from other data sources. A good example in the case of aquaculture would be the estimation of water temperature data based on meteorological variables such as air temperature and wind speed (Ross et al., 2011 & Aguilar-Manjarrez J. & Nath S., 1998). Ultimately choice of indicators should be based on practical considerations and result from a consensus of opinions provided by experts (top down) and local interests (bottom up) (Bell and Morse, 2008). Table 7 provides an example of some potential indicators, approaches and tools associated with assessing physical, production, ecological, and social carrying capacity.


Table 7: Examples of indicators for the four components of carrying capacity along with potential measures and modelling tools. (Adapted from Ross et al., 2011. Original source: Ferreira et al., 2011)

Type of carrying capacity

Indicators Measures / approaches Models / tools

Physical Water availability Water access Water quality Hydrography Hydrodynamics

Inventory of aquaculture Site selection Zoning Water management ICZM, climate change RA Transboundary waterbodies / watersheds

GIS. e.g.: Arc-info (ESRI), IDRISI (Clark Labs) Mapinfo (Pitney Bowes) GRASS (grass.fbk.eu) Google Earth (earth.google.com) Surfer (Golden Software)

Production Intensity of production Yield Investment Market value Economic indicators

Optimisation Management Area Management Cluster management

POND (www.longline.co.uk) FARM (www.longline.co.uk) Winshell (www.longline.co.uk) INVESTMENT (FAO model) Many proprietary model options (e.g. operated by aquaculture companies)

Ecological Waste dispersion Habitat deterioration Dissolved nutrients Eutrophication Benthic hypoxia

Monitoring Risk assessment Biodiversity and Exotics Resource (e.g. habitat) mapping

DEPOMOD (Cromey et al., 2002,b) STELLA (www.iseesystems.com) Vensim (www.vensim.com) Powersim (www.powersim.com) GIS (see above)

Social Space conflict Employment Livelihood Acceptability Value to the community West: regulation East: flexibility

Participatory Transparency Advocacy Identify stakeholders

Based on perceptions May be non-quantitative

The use of spatial planning tools such as Geographic Information Systems (GIS) has significant potential in aquaculture planning and is viewed as an essential part of the EAA (FAO, 2010c & Ross et al., 2011). The primary use of GIS in relation to aquaculture is to guide site selection by allowing multiple data sources and considerations (e.g. environmental, physical, administrative and social) to be combined and weighed against each other in a single system. Box 4 shows an example a complex GIS based aquaculture site selection model that places considerable emphasis on environmental capacity and impact. Using GIS modelling has the potential to save considerable time, effort and expense by indicating potential aquaculture sites thus reducing the risk of conducting detailed site specific investigations for locations that may ultimately prove to be unsuitable. As well as general site suitability models GIS and spatial analysis can be used to address specific issues ranging from relatively simple spatial and distance questions such as quantity of production within a given area to more complex issues such as analysis of visual impacts from potential aquaculture operations and modelling of waste dispersion from fish cages (Corner et al., 2006 & Ross, Handisyde & Nimmo, 2009).


A good overview of the principles behind the use of GIS in relation to aquaculture is provided by Nath et al. (2000). African specific examples include Aguilar-Manjarrez J. & Nath S. (1998) who used a GIS based site selection model to assess potential site suitability for pond based aquaculture across the entire continent. More recent African examples of GIS site suitability modelling for aquaculture can be found for Ghana (Asmah, 2008) and Sierra Leone (Sankoh, 2009).

2.6 Summary Aquaculture makes significant contributions to income and food security in many regions and is set to continue to expand. There is also a trend for growing concern over environmental issues and an increasing awareness of the need for sustainable development. Aquaculture production will always result in some degree of environmental modification and if poorly managed there may be negative consequences for ecosystems into which peoples livelihoods will be invariably linked. It should also be remembered that aquaculture itself is dependent on the environment in which it operates and may be vulnerable to environmental impacts such as contamination of water bodies by other users.

Box 4. Combination of several carrying capacity categories into a holistic decision support process for salmon culture in cages. (after Hunter, 2009). The structural diagram shows primary data (pink) feeding into sub-models (yellow) and then final models (blue) which address system-specific site selection (physical capacity, and there sub-components of ecological capacity: biodiversity, waste dispersion and visual impact. Each major component (blue) is a free-standing decision process but weighted combination of the model outcomes (green) can drive the overall decision process.

Source of text and image: Ross et al. (2011)

Biodiversity[Environmental

carryingcapacity]

Viewshed[Social

carrying capacity]

Waste dispersion

[Environmentalcarrying

capacity]

Site selection[Physical carrying Capacity]

Overall DecisionSupportprocess

PRIMARY DATA

PRIM

ARY

DAT

A

PRIMARY DATA

Wave Climate Currents Bathymetry Sediment Type

Protected Areas

EndangeredSpecies

Species Sensitiveto Aquaculture

Habitat & Species Distribution

Commercial Fisheries

DEM VIEWPOINTS

Currents

PRIM

ARY D

ATA

Bathymetry

Hydrography

HydrologicalProcesses


Current thinking suggests that aquaculture along with other livelihood strategies do not operate in isolation either from each other or the surrounding ecosystem. Therefore if development is to be sustainable and not greatly benefit some at the expense of others then a considered and holistic approach is needed such as that prescribed by the Ecosystem Approach to Aquaculture. To support such an approach there is a need to understand and be able to estimate potential impacts and the carrying capacity of the environment i.e. its ability to support the activity in question without changing in a way that is considered unacceptable. A range of tools and approaches exist that can help model and assess potential environmental impacts and in doing so help guide aquaculture development to allow for best use of resources and thus greatest benefit at least environmental cost. Hopefully increased environmental understanding will allow for successful and sustainable development of the aquaculture sector through informed policy making and the application of both private and public regulation and standards.


3 The concept and practicalities of aquatic system health with respect to aquaculture production

3.1 Aquatic ecosystem health The concept of aquatic ecosystem health with respect to aquaculture production is here used to describe the impact of aquaculture processes on an aquatic ecosystem - a biological community and its physical environment. The health or balance of an ecosystem is degraded when the ecosystems ability to absorb or deal with external stressors has been exceeded. In an aquaculture context, these may include physical changes in the form of topographic alterations to a water body or water flow capacity and direction, chemical changes in the form of alterations in loading rates of biostimulatory nutrients, oxygen consuming materials, chemical thereupeutants, toxins or variations in salinity and biological alterations may include introduction of exotic species that affect the biodiversity of the system.

Pullin et al. 2007 state that the history of aquaculture, like that of agriculture, has been responsible for many examples of adverse environmental impacts and lack of sustainability and concludes by saying that such a history cannot continue indefinitely. They suggest that aquaculture needs a fundamental transition from management that is based solely on maximising the exploitable biomass of target species to the transition to an integrated management of natural resources and ecosystems that has a broader application and applies at farm level and also to entire watersheds, coastal zones and open waters. In recent years the term sustainable development and its application to aquaculture has recently come to the forefront (Folke and Kautsky, 1992; Pillay, 1997; Naylor et al. 2000; Pullin et al., 2007). According to FAO (1988) sustainable development can be defined as The management and conservation of the natural resource base, and the orientation of technological and institutional change in such a manner as to ensure the attainment of continued satisfaction of human needs for present and future generations. Such sustainable development conserves (land) water, plants and (animal) genetic resources, is environmentally non-degrading, technologically appropriate, economically viable and socially acceptable. Three principles of sustainability relating to the sound management of natural resources were further defined as the need to: 1) conserve (and sustain) the multiple resource in its environment; 2) satisfy the social and economic needs of human beings; 3) for management to guide the required changes in institutions and technology.

Whilst, globally, aquaculture is dominated by smallholder and small company production in tropical and sub-tropical countries, particularly in Asia where 92% of global aquaculture production occurs (Tacon et al., 2010), it also encompasses billion dollar international companies. Such an evolution of this diverse and varied sector presents negative impacts on the environment when unregulated and badly managed and such a rapid growth naturally raises concerns about the environmental sustainability of future industry growth. There are a number of key, specific issues or areas of risk that exist highlighting perceived unsustainable aquaculture practices with potential negative impacts and include the following;

Environmental impacts on ecosystem function and biodiversity Food quality and contamination (food safety)


Pathogen diagnosis and control.

3.2 Aquaculture production systems and environments Globally, the aquaculture sector shows a remarkable diversity (FAO, 2010a). Broadly speaking, production environments can be divided into inland (freshwater) and coastal (marine and brackish water) habitats and production systems can vary according to the intensity of stocking densities, type of cultured species and amount of feed input (see Tables 8-11).

3.2.1 Freshwater

3.2.1.1 Ponds, tanks, raceways and cages

Freshwater aquaculture production includes a range of containment systems that range from static water bodies e.g. ponds and lakes to high flow through systems, indeed freshwaters were the source of 60% of global aquaculture production in 2008, despite the fact that they constitute only 3% of the planets water. Of this, semi-intensive pond culture of carp and other cyprinids dominates this category at 65.9% while highly stocked salmonid farming (mainly rainbow trout in freshwater) makes up only 1.5%, typically in concrete raceways or other similar systems requiring high throughput of water. Tilapia constituted 7.6% of freshwater production in a mix of system from extensive to highly intensive. Cage-based aquaculture in freshwater lakes and rivers has expanded in recent years i.e. in Egypt, Vietnam and most recently Ghana.

3.2.2 Coastal i.e. marine and brackish water

3.2.2.1 Ponds, tanks and raceways

Brackish water coastal ponds and lagoons are exploited for extensive fish, mollusc, crustacean and seaweed production. They have also been used in temperate climates for brackish fish species and also, more successfully, for intensive culture of penaeid species, who expansion in the last 30 years has resulted in a production that now accounts for about 58% of aquaculture production from brackish water. Coastal aquaculture using onshore tanks has recently developed e.g. South Korea, Spain and Iceland using pumped water that flows directly out of the system into the environment although the use of recirculation systems is developing (see Section 3.2.3).

3.2.2.2 Cages

Floating cages in a marine environment are used for mid to high value marine fish species across a range of farm sizes and environments (Bostock et al., 2010). They offer an open exchange of water through the nets which replenishes oxygen and removes dissolved and solid wastes and rely on feeding with either complete pelleted diets or with trash fish. Cage unit size and arrangement is flexible to meet farm requirements and require a high management cost, especially in more exposed locations in the form of specialized service vessels and equipment and automated feeding systems.


3.2.2.3 Marine mollusks and aquatic plants

Extractive species that use nutrients and carbon directly from the environment such as bivalves and macroalgae i.e. they do not require feed input. Therefore cultivation methods are simple however, since the 1990s, a significant up scaling of production has been the result of the introduction of specialized equipment and greater labour efficiencies.

3.2.3 Recirculated aquaculture systems (RAS) RAS culture systems are typically land-based and use containment systems such as tanks or raceways for the fish with a percentage of effluent water passed back through the system following treatment and waste removal.

Table 8: The generic species groupproduction systems. The subscript c denotes a coastal system and i denotes an inland (freshwater) system; ci indicates that the system occurs in both inland and coastal systems. Adapted from Hall et al., 2011

Species Group Bottom Culture

Off-Bottom Culture

Cages & Pens

Ponds Tanks and raceways

Rirculated aquaculture

systems (RAS)

Bivalves xc xc xci Carps xi Catfish xi xi xci Crabs and Lobsters xc xci Eels xi xc xci Gastropods xc Other Finfish xc xci xci Other Invertebrates xci Salmonids xc xci xci Shrimps and Prawns xci Tilapias xci xci xci Table 9: Summary of feed types used in aquaculture (After Neori et al., 2004; de Silva and Hasan, 2007). From Hall et al., 2011

Feed category Description Natural feeds Plant materials, mainly crop waste, used in

environmental strategies for aquaculture

Documents