Ultimately, sustainability may be the aquaculture industry’s ability to adapt on a planet with an ever increasing human population which continues to consume its limited supply of non-renewable resources at an alarming rate.

Although ever increasing costs of resources such as oil and water continue to apply pressure to the development of sustainable models across all spectra of human endeavor, the discussion around sustainable aquaculture is not exactly new. Sustainable Aquaculture Development and the Code of Conduct for Responsible Fisheries was presented by William D. Dar to the FAO, Rome in March 1999.

Sustainability is also not just a concern of aquaculture – the broader concerns of ocean governance has also been considered by George Pararas-Carayannis in Ocean Governance and Sustainability – Present Trends – Future Challenges. From the abstract:

The ability of marine ecosystems to produce the economic and ecological goods and services that are desired and needed, have been substantially reduced. In some instances there has been a significant decline of ocean wildlife and even collapses of ocean ecosystems. It is clearly evident that what we once considered to be inexhaustible and resilient is, in fact, finite and fragile.

Patrick Sorgeloos offers comment regarding Technologies for Sustainable Aquaculture Development. From the introduction:

Risks of major environmental and human-health problems need to be weighed against achieving a more cautious rise in production that is, in the longer term, sustainable. We should all see this not only as a challenge to do it well and responsibly, but also as a commercial opportunity for the industry.

Aquaculture is clearly at a crossroads and can come, in fact, should come of age in the twenty-first century. However, this will require more responsible researchers and more integrated R&D approaches than we apply at present.

Denis Bailly and Rolf Willmann have provided research findings entitled Promoting Sustainable Aquaculture through Economic and other Incentives. From the abstract:

Economic incentives have been widely applied to encourage growth in aquaculture production, especially in the “infant” phase of development where risks are often high and scale economies cannot yet be realized. In recent years, increasing attention has been given to incentives that encourage the use of environmental and natural resources in a sustainable manner. This growing interest is not least due to the frequently disappointing performance of command and control measures. Different kinds of incentives can be developed in isolation or in combination, including tradable use/access rights, taxes/subsidies, codes of conduct, eco-labelling and others. While practical experiences are still very limited in aquaculture, these measures have proven effective in other sectors to induce producers to adopt better and more environmentally friendly production practices.

Developments during the past two years confirm the trends already observed at the end of the 1990s: capture fisheries production is stagnating, aquaculture output is expanding and there are growing concerns with regard to the livelihoods of fishers and the sustainability of commercial catches and the aquatic ecosystems from which they are extracted. The State of World Fisheries and Aquaculture 2004 reports on several of these issues.

It is not only fishers and fish farmers who have these concerns; they are increasingly shared by civil society at large. Moreover, the importance of international trade in fish and fish products, combined with the trend for major fishing and trading companies to operate on a multinational basis, means that such issues are becoming global in nature – affecting a growing number of countries, be they large fish producers or large consumers of fish. It is heartening to note that governments and other stakeholders have begun to collaborate with their neighbours and partners in trade in an effort to find shared solutions.

Concrete examples of positive outcomes of this “globalization of concerns” are the establishment of new regional fishery management organizations and the strengthening of existing ones. It is probable that ongoing discussions among intergovernmental organizations on topics such as trade in endangered aquatic species, the use of subsidies in the fishing industry, and labour standards in fisheries will also result in agreements of overall benefit to world society.

Given the nature and tone of the international discussion on fishery issues and the developments observed during recent years, I believe that fishers and fish farmers, in collaboration with governments and other stakeholders, will overcome the obstacles they face currently and will succeed in ensuring sustainable fisheries and continued supplies of food fish at least at their present levels.

Science magazine (3 November 2006: Vol. 314. no. 5800, pp. 787 – 790 DOI: 10.1126/science.1132294) reported a less bright future: (from the reprint summary)

A Need for a Sea Change
The significance of the ocean’s declining diversity on humanity has been difficult to assess. In a series of meta-analyses, Worm et al. (p. 787; see the news story by Stokstad [a summary, the balance by subscription]) quantify how the loss of marine diversity on local, regional, and global scales has affected the functioning and stability of marine ecosystems, the flow of ecosystem services, and the rise of associated risks to humanity. Similar relationships occur between biodiversity change and ecosystem services at scales ranging from small squaremeter plots to entire ocean basins; this finding implies that small-scale experiments can be used to predict large-scale ocean change. At current rates of diversity loss, this analysis indicates that there will be no more viable fish or invertebrate species available to fisheries by 2050. However, the results also show that the trends in loss of species are still reversible.

The abstract is available, the article is by subscription. New Scientist magazine carry more freely available coverage of the results of Worm’s (et al) research.

Many fisheries scientists have been sceptical of the idea that damage to a few non-fish species could be a threat to major fish stocks. But this study demonstrates, for the first time, that commercial and ecological health go together in the ocean. “Every species matters.”

In a separate article, New Scientist report that striking the balance between the need to conserve wild stocks and economic imperatives continue to challenge policy makers and the fishing industry; leading to some unhappy compromises.

The abstract:

The various sea farming and sea ranching practices used in the People’s Republic of China are reviewed, based on published and unpublished information, statistical data and field experiences. The development of marine fisheries during the past 50 years is described. Following their decline caused by overfishing and the ecological degradation of the coastal environment, emphasis was shifted from marine capture fisheries to aquaculture-based operations, including farming and ranching of marine organisms both in inshore and offshore areas. The biology and culture of major representatives of five species groups (seaweed, molluscs, crustaceans, echinoderms and fish), involving a total of 67 different species, are presented, together with detailed production statistics. The eight sea farming and ranching systems actually used in China are presented. Several aspects related to marine resources management for sea farming and ranching are discussed, such as legislation, research on genetics and biodiversity, health management and marine habitat rehabilitation. Monitoring and evaluation according to biological, environmental and socio-economic standards are briefly considered.

For 2002 and 2003, monitoring activity of problems in large-scale hatchery rearing of crab larvae was done to identify windows of opportunity for probiotic application. These led to identification of various microbial fouling and disease-causing organisms in spawned eggs and hatchery-reared larvae.

Celia R. Lavilla-Pitogo and Leobert D. de la Pena, from the Aquaculture Department, Southeast Asian Fisheries Development Center Tigbauan, Iloilo, Philippines; published a report (December 2004) entitled Diseases in Farmed Mud Crabs Scylla spp.: Diagnosis, Prevention, and Control. From the forward:

Aquaculture production has suffered many set-backs due to the occurrence of diseases. Many of the diseases are caused by infectious organisms that are difficult to detect and need sophisticated instruments for diagnosis, but most disease occurrence and mortality in farmed aquatic animals are related to poor rearing water quality. It is, therefore, important for technicians and farmers to recognize the relationship between the animals they culture and the aquatic environment. The Government of Japan, through the Regional Fish Disease Project, funded research on diseases affecting mud crabs in order to come up with sound prevention and control methods.

This book is a collection of observations gathered from various research and commercial culture activities, and gives emphasis on disease recognition using simple techniques and gross observations of affected crabs. However, since many of the diseases are caused by microorganisms, microscopy is an important technique for their diagnosis. The authors of the book encourage active cooperation between farmers and diagnostic laboratories for disease identification, prevention, and control in order to build up more information to increase production. The Regional Fish Disease Project supports sustainable mud crab production and hopes that farmers and other users of this book will attain their production goals.

The report is located within a framed web site. Chapter 1 includes information about diseases in eggs and larvae. Chapter 2 includes information about diseases in juveniles and adults. The appendix includes documentation of various microscopy techniques. There is also a glossary.

The Science and Development Network sumarises, and the New Agriculturalist reports on research to more closely integrate crab culture with sustainable mangrove management. From the introduction:

The rapid spread of aquaculture in recent decades has brought riches to some, ruin to many, exclusion to the poorest coastal dwellers, and environmental degradation. Scientists in the Philippines are adapting aquaculture to make it sustainable over the long term and suitable for small-scale, family-level operators. An innovative system of captive crab culture in live mangrove is being developed in the central Philippines and is now being verified and demonstrated on the southern island of Mindanao.

The Culture and Management of Scylla Species (CAMS) project was a collaboration among four institutions worldwide – the University of Wales (Bangor) in the United Kingdom, Artemia Reference Center of the University of Ghent in Belgium, Can Tho University in Vietnam, and SEAFDEC/AQD in the Philippines. The CAMS project has reported on aquasilviculture projects in the Philippines and Vietnam. The objective: To refine systems for integrated aquasilviculture of mud crabs within mangroves, specifically by reducing fish biomass requirement through low cost incomplete feeds and utilization of natural productivity. The aquasilviculture reports are available online.

Objectives of the Code of Practice
• To define principles, guidelines, and best practices for responsible aquaculture in mangrove ecosystems in Southeast Asia
• To provide a tool to guide States, non-government organizations, research and academic institutions, aquaculture practitioners, mangrove managers, local communities, global and regional aid and financial institutions, and other stakeholders concerned with both responsible aquaculture and the conservation and sustainable use of mangrove ecosystems
• To recommend key legislation and enforcement mechanisms to ensure both responsible aquaculture and the conservation and sustainable use of mangroves.

From the introduction:

Mangrove ecosystems (or simply ‘mangroves’) are the tide-influenced wetland complex consisting of mangrove forests, estuaries, lagoons, and associated habitats along the coasts and around islands in the tropics and subtropics. The mangrove forest consists of seawater-adapted flowering trees and shrubs, and the many associated ferns, fungi, and algae, including many epiphytes. The ‘true mangrove’ plants are members of the genera Rhizophora, Bruguiera, Ceriops, Avicennia, Sonneratia, Xylocarpus, Heritiera, and Excoecaria.

Mangroves support microscopic to large, terrestrial and aquatic (marine and freshwater), transient and resident wildlife. The mangrove physical environment includes waterways, mudflats, salt pans, and islands, with a wide ranges of salinities, daily tidal flood and ebb, and anaerobic mud bottoms.

Subtitled The Socio-economic Situation of Human Settlements in Mangrove Forests, the introduction has this to say:

More than half the world’s people live in coastal regions, utilizing such resources as salt, minerals, fish, and crustaceans, the products of mangroves, salt marsh, seagrass, and kelp, energy from wind, waves, and tides, and such materials as sand, gravel, clay, and limestone, all obtained from the coast or the adjacent sea. Moreover, the coast provides sites for settlement, agriculture and aquaculture, ports and harbours, industry, commerce, and recreation. The management of coastal environments and their resources has raised many problems in both developed and developing countries, and it was felt appropriate that the United Nations University should give emphasis to this field of study.

The Coastal Resources Management Project was initiated as part of the University’s Natural Resources Programme. It was decided that the coastal environment – comprising the foreshore (between high and low tide lines), backshore (above high tide line to the landward limit of marine influences), and nearshore (from low tide line out to a depth of 20 metres) zones was a distinctive field for research and training that merited its own project within the programme.

A number of research studies and workshops were commissioned under this theme. Man in the Mangroves contains papers presented at a UNU-sponsored workshop. Three of the papers result from UNU research. The remainder were submitted by independent researchers. They focus on the socio-economic aspects of the use, development, and management of mangrove areas in relation to environmental and ecological factors.

Although the Coastal Resources Management Project has now been concluded, the University’s new programme on Resource Policy and Management has undertaken to maintain an international dimension in research, training, and dissemination, stressing the interaction of resource management, conservation, and development.

From the report:

In Flecheiras, seaweed cultivators adopt the following method. A rope structure is attached to the sea bed and to buoys near the beach, and seaweed plants are cultivated in the rope. Planting is therefore carried out in shallow waters, and caring for the crop is done through frequent visits by boat. After approximately 3½ months, the plants can be harvested, cleaned and dried for retail. In general, seaweed loses about 80 per cent of its weight after drying. It is possible to cultivate several tonnes of seaweed in each location and studies have been made into the possibility of reducing the growing period. This would have the combined benefit of increasing income and reducing the seasonality of production. In areas such as Flecheiras and Guajiru, harvest periods as low as two months have been achieved.

There has been other research into the non-edible qualities of Brazilian seaweeds – the Brazilian Journal of Biology, vol.63 no.4 São Carlos Nov. 2003, has published research findings by Pereira, da Gama, Teixeira, and Yoneshigue-Valentin. The researchers noted that the Brazilian red seaweed Laurencia obtusa inhibited feeding by herbivores, and conducted research to discover what compounds were present in the plant. From the abstract:

Laboratory and field experiments were performed to assess the ecological roles of natural products produced by the Brazilian red seaweed Laurencia obtusa. Laboratory assays revealed that the natural concentration of the crude organic extract of L. obtusa significantly inhibited feeding by two herbivores: the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. It was verified that this chemically defensive action was due to halogenated sesquiterpenoid elatol, found to be the major natural product of this red seaweed. In addition, it was verified that the antifouling property of the chemicals produced by L. obtusa could make this red alga less attractive for fish grazing. Direct protection against two herbivore species and indirect protection against herbivory by fouling inibition constitute evidence that the major natural product from Brazilian L. obtusa plays multiple environmental roles, thereby increasing the adaptive value of these metabolites. On the other hand, the evidence reinforces the idea that marine natural products may have different functions in the sea.

The main idea behind the programme was that while magur (African catfish, Clarias gariepinus) is a good fish to be grown, because of its high growth rate, disease resistance, ability to take up oxygen from the air, etc., most local people were not aware of the potential of this fish. A few households in the CPP area had already been growing magur on their homesteads. This method proved to be successful, so CPP has taken up the task to spread this local knowledge among other households with emphasis on professional fishermen, landless, and other poor people. Initially 200 households joined the Chari in the Bari programme.

According to tve.org the African catfish Clarias gariepinus is one of the most suitable species for aquaculture in Africa. Since the 1970s it has been considered to hold great promise for fish farming in Africa. The African catfish has a high growth rate, is very resistant to handling and stress, and is very well appreciated in a wide number of African countries, including Nigeria (where it is often referred to as lungfish).

The FAO have produced a free document Artificial Reproduction and Pond Rearing of the African Catfish Clarias Gariepinus in Sub-Saharan Africa – A Handbook, edited by Gertjan de Graaf and Hans Janssen, from the Nefisco Foundation mentioned above.

Research has also been conducted in Brazil – Dietary canitine maintains energy reserves and delays fatigue of exercised african catfish (Clarias gariepinus) fed high fat diets effectively exploring better diets – which should lead to better growth patterns.

Rhodes University offer a free, online Clarias husbandry manual. They observe:

The African sharptooth catfish, Clarias gariepinus, is undoubtedly a remarkable and fascinating beast. Biologically it has all the attributes of a premier aquaculture species. Its biology, ecology and life history is well known and documented. From a teaching point of view this makes it an ideal species, allowing students to obtain an insight into how natural history information can be used for the development of culture technologies. Despite the technological know-how, total production of clariid catfish in Africa in 1993 has been estimated at a mere ca. 4500 tons. Despite the fact that there may be a considerable margin of error in the reported production figures, the farming of catfish in Africa is still a marginal activity. The reasons for this are manifold and can be primarily pinned on market forces, inadequate regional infrastructures, production costs, the socio-economics of fish farming and the underlying philosophy upon which aquaculture development in Africa is still largely based. Nevertheless the future potential for the farming of Clarias gariepinus throughout its distributional range is immense.

This large document (93 pages), is written for the beginning aquaculturist. It focuses which plants and animals to grow, and how to grow them with a minimum investment in land and equipment. The basics are covered, and then there’s added value with information on such subjects as pond management and water recycling. The manual has numerous valuable tables and drawings. While this manual is written to be an effective guide to backyard aquaculture for Hawaii, the principles hold true anywhere.

In this book, the terms “backyard” and “small-scale” generally refer to systems larger than home aquariums, but no larger than ponds of about one acre, a size range that takes in many possibilities. Many excellent books on aquarium-keeping are available for people with that interest, and a great number of works have been written on large-scale commercial aquaculture.

This book will provide a starting point and information source for individuals interested in learning more about backyard aquaculture, or in starting up a small-scale culture system. It will present information to help you decide whether this kind of activity will be possible and enjoyable for you; suggest an orderly approach to maximize your chances for success; present some detail on how to accomplish necessary tasks and start up some specific culture systems; and serve as a source of reference materials for further or more detailed reading.