M. C. M. Beveridge

Effect of aquaculture on world fish supplies

Global production of farmed fish and shellfish has more than doubled in the past 15 years. Many people believe that such growth relieves pressure on ocean fisheries, but the opposite is true for some types of aquaculture. Farming carnivorous species requires large inputs of wild fish for feed. Some aquaculture systems also reduce wild fish supplies through habitat modification, wild seedstock collection and other ecological impacts. On balance, global aquaculture production still adds to world fish supplies; however, if the growing aquaculture industry is to sustain its contribution to world fish supplies, it must reduce wild fish inputs in feed and adopt more ecologically sound management practices.

Does aquaculture add resilience to the global food system

Aquaculture is the fastest growing food sector and continues to expand alongside terrestrial crop and livestock production. Using portfolio theory as a conceptual framework, we explore how current interconnections between the aquaculture, crop, livestock, and fisheries sectors act as an impediment to, or an opportunity for, enhanced resilience in the global food system given increased resource scarcity and climate change. Aquaculture can potentially enhance resilience through improved resource use efficiencies and increased diversification of farmed species, locales of production, and feeding strategies. However, aquaculture’s reliance on terrestrial crops and wild fish for feeds, its dependence on freshwater and land for culture sites, and its broad array of environmental impacts diminishes its ability to add resilience. Feeds for livestock and farmed fish that are fed rely largely on the same crops, although the fraction destined for aquaculture is presently small (∼4%). As demand for high-value fed aquaculture products grows, competition for these crops will also rise, as will the demand for wild fish as feed inputs. Many of these crops and forage fish are also consumed directly by humans and provide essential nutrition for low-income households. Their rising use in aquafeeds has the potential to increase price levels and volatility, worsening food insecurity among the most vulnerable populations. Although the diversification of global food production systems that includes aquaculture offers promise for enhanced resilience, such promise will not be realized if government policies fail to provide adequate incentives for resource efficiency, equity, and environmental protection.

Periphyton: ecology, exploitation and management.

Periphyton, as described in this book, refers to the entire complex of attached aquatic biota on submerged substrates, including associated non-attached organisms and detritus. Thus the periphyton community comprises bacteria, fungi, protozoa, algae, zooplankton and other invertebrates. Periphyton is important for various reasons: as a major contributor to carbon fixation and nutrient cycling in aquatic ecosystems; as an important source of food in aquatic systems; as an indicator of environmental change. It can also be managed to improve water quality in lakes and reservoirs; it can greatly increase aquaculture production; it can be used in waste water treatment. The book provides an international review of periphyton ecology, exploitation and management. The ecology part focuses on periphyton structure and function in natural systems. The exploitation part covers its nutritive qualities and utilization by organisms, particularly in aquaculture. The final part considers the use of periphyton for increasing aquatic production and its effects on water quality and animal health in culture systems.

The European consumers’ understanding and perceptions of the “organic” food regime: The case of aquaculture

This paper explores consumer understanding and perception of organic food, with specific reference to the relatively new concept of organic farmed salmon. Key themes associated with the term “organic” and its meaning, as determined by consumers, are explored and the role of labelling and regulatory authorities considered. Focus groups in five countries (UK, Germany, Spain, Norway and France) consisting of 196 participants showed that most consumers are confused about the meaning of the term organic and are largely unaware of the organic certification and labelling process. Many consumers were unsure, even sceptical about the concept of organic farmed salmon and display a large amount of distrust in the regulatory process. The implications for the concept of organic food and salmon production and directions for further research are discussed.

Tilapias : biology and exploitation

Preface. 1. Evolution, phylogenetic relationships and biogeography B.M. McAndrew. 2. Reproductive biology, mating systems and parental care G.A. Turner, R.F. Robinson. 3. Diet, feeding and digestive physiology M.C.M. Beveridge, D.J. Baird. 4. Environmental physiology and energetics L.G. Ross. 5. The role of tilapias in ecosystems R.H. Lowe-McConnell. 6. Population dynamics and management K. Lorenzen. 7. Genetics for the management and improvement of cultured stocks D. Penman, B.J. McAndrew. 8. Strategies for seed production D.C. Little, G. Hulata. 9. Nutritional requirements K. Jauncey. 10. Semi-intensive pond aquaculture C. Kwei Lin, et al. 11. Production in intensive and recycle systems J.F. Muir, et al. 12. Economics and Marketing J.A. Young, J.F. Muir.

Cultured fish: integrative biology and management of domestication and interactions with wild fish

Fish aquaculture for commodity production, fisheries enhancement and conservation is expanding rapidly, with many cultured species undergoing inadvertent or controlled domestication. Cultured fish are frequently released, accidentally and deliberately, into natural environments where they may survive well and impact on wild fish populations through ecological, genetic, and technical interactions. Impacts of fish released accidentally or for fisheries enhancement tend to be negative for the wild populations involved, particularly where wild populations are small, and/or highly adapted to local conditions, and/or declining. Captive breeding and supplementation can play a positive role in restoring threatened populations, but the biology of threatened populations and the potential of culture approaches for conserving them remain poorly understood. Approaches to the management of domestication and cultured‐wild fish interactions are often ad hoc, fragmented and poorly informed by current science. We develop an integrative biological framework for understanding and managing domestication and cultured‐wild fish interactions. The framework sets out how management practices in culture and for cultured fish in natural environments affect domestication processes, interactions between cultured and wild fish, and outcomes in terms of commodity production, fisheries yield, and conservation. We also develop a typology of management systems (specific combinations of management practices in culture and in natural environments) that are likely to provide positive outcomes for particular management objectives and situations. We close by setting out avenues for further research that will simultaneously improve fish domestication and management of cultured‐wild fish interactions and provide key insights into fundamental biology.

Meeting the food and nutrition needs of the poor: the role of fish and the opportunities and challenges emerging from the rise of aquaculture.

People who are food and nutrition insecure largely reside in Asia and Sub-Saharan Africa and for many, fish represents a rich source of protein, micronutrients and essential fatty acids. The contribution of fish to household food and nutrition security depends upon availability, access and cultural and personal preferences. Access is largely determined by location, seasonality and price but at the individual level it also depends upon a persons physiological and health status and how fish is prepared, cooked and shared among household members. The sustained and rapid expansion of aquaculture over the past 30 years has resulted in >40% of all fish now consumed being derived from farming. While aquaculture produce increasingly features in the diets of many Asians, it is much less apparent among those living in Sub-Saharan Africa. Here, per capita fish consumption has grown little and despite the apparently strong markets and adequate biophysical conditions, aquaculture has yet to develop. The contribution of aquaculture to food and nutrition security is not only just an issue of where aquaculture occurs but also of what is being produced and how and whether the produce is as accessible as that from capture fisheries. The range of fish species produced by an increasingly globalized aquaculture industry differs from that derived from capture fisheries. Farmed fishes are also different in terms of their nutrient content, a result of the species being grown and of rearing methods. Farmed fish price affects access by poor consumers while the size at which fish is harvested influences both access and use. This paper explores these issues with particular reference to Asia and Africa and the technical and policy innovations needed to ensure that fish farming is able to fulfil its potential to meet the global populations food and nutrition needs.

The effects of density, light and shelter on the growth and survival of African catfish (Clarias gariepinus Burchell, 1822) fingerlings

The effects of stocking density, light and shelter on the growth and survival of Clarias gariepinus fingerings was evaluated. In this experiment African catfish with initial individual mean weight 0.79±0.1 g were reared at two different stocking densities—5 fish l−1 and 10 fish l−1 in either sheltered or unsheltered tanks with reduced and normal light condition. In all conditions growth rate was significantly affected by stocking density. The growth rate was significantly higher at low densities and in reduced light conditions where shelter was provided. Survival rate was in excess of 79% in all treatments and was not affected by treatment.

The ingestion of bacteria in suspension by the tilapia Oreochromis niloticus

Abstract Tilapia ( Oreochromis niloticus ) fry were exposed to concentrations of the bacterium Chromobacterium violaceum in order to establish whether they can detect and ingest unattached bacteria. Groups of fish exposed to both bacteria and to cell-free bacterial extracts showed a significant increase in opercular beat rates, thus demonstrating that they are able to detect the presence of unattached bacteria in suspension. Examination of the stomach contents showed that bacteria were ingested and that there was a significant, positive correlation between ingestion and concentration in the trial media.

The application of geographical information systems to site selection for coastal aquaculture : an example based on salmonid cage culture

Abstract The potential of a simple, PC-based geographical information system (GIS) for site selection in coastal aquaculture was assessed using as an example a salmonid cage culture development in Camas Bruaich Ruaidhe, Oban, Argyll, Scotland. Data on bathymetry, current, shelter and water quality variations were used to determine the suitability of the site. The GIS results suggested that a total of 1.26 ha (6.4% of the total area) was suitable for cage culture. A general methodology for systematic spatial analysis for aquaculture is proposed, although this needs to be varied according to circumstances in a site-specific way.