Showing papers in "Reviews in Aquaculture in 2013"

Feeding behaviour and digestive physiology in larval fish: current knowledge, and gaps and bottlenecks in research

Abstract: Food uptake follows rules defined by feeding behaviour that determines the kind and quantity of food ingested by fish larvae as well as how live prey and food particles are detected, captured and ingested. Feeding success depends on the progressive development of anatomical characteristics and physiological functions and on the availability of suitable food items throughout larval development. The fish larval stages present eco-morpho-physiological features very different from adults and differ from one species to another. The organoleptic properties, dimensions, detectability, movements characteristics and buoyancy of food items are all crucial features that should be considered, but is often ignored, in feeding regimes. Ontogenetic changes in digestive function lead to limitations in the ability to process certain feedstuffs. There is still a lack of knowledge about the digestion and absorption of various nutrients and about the ontogeny of basic physiological mechanisms in fish larvae, including how they are affected by genetic, dietary and environmental factors. The neural and hormonal regulation of the digestive process and of appetite is critical for optimizing digestion. These processes are still poorly described in fish larvae and attempts to develop optimal feeding regimes are often still on a ‘trial and error’ basis. A holistic understanding of feeding ecology and digestive functions is important for designing diets for fish larvae and the adaptation of rearing conditions to meet requirements for the best presentation of prey and microdiets, and their optimal ingestion, digestion and absorption. More research that targets gaps in our knowledge should advance larval rearing.

Fish larval nutrition and feed formulation - knowledge gaps and bottlenecks for advances in larval rearing

Abstract: Despite considerable progress in recent years, many questions regarding fish larval nutrition remain largely unanswered, and several research avenues remain open A holistic understanding of the supply line of nutrients is important for developing diets for use in larval culture and for the adaptation of rearing conditions that meet the larval requirements for the optimal presentation of food organisms and/or microdiets The aim of the present review is to revise the state of the art and to pinpoint the gaps in knowledge regarding larval nutritional requirements, the nutritional value of live feeds and challenges and opportunities in the development of formulated larval diets

Skeletal anomalies in reared European fish larvae and juveniles. Part 2: main typologies, occurrences and causative factors

Abstract: The presence of skeletal anomalies in farmed teleost fish is currently a major problem in aquaculture, entailing economical, biological and ethical issues. The common occurrence of skeletal abnormalities in farmed fish and the absence of effective solutions for avoiding their onset or definitely culling out the affected individuals as early as possible from the productive cycle, highlight the need to improve our knowledge on the basic processes regulating fish skeletogenesis and skeletal tissues differentiation, modelling and remodelling. Severe skeletal anomalies may actually occur throughout the entire life cycle of fish, but their development often begins with slight aberrations of the internal elements. Comprehensive investigation efforts conducted on reared larvae and juveniles could provide a great contribution in filling the gap in knowledge, as skeletogenesis and skeletal tissue differentiation occur during these early life stages. The aim of this review is to provide a synthetic but comprehensive picture of the actual knowledge on the ontogeny, typologies and occurrence of skeletal anomalies, and on the proposed causative factors for their onset in larvae and juveniles of European farmed fish. The state-of-art of knowledge of these issues is analysed critically intending to individualize the main gaps of knowledge that require to be filled, in order to optimize the morphological quality of farmed juveniles.

Gamete quality and broodstock management in temperate fish

Abstract: The ability to fully control sexual maturation and spawning and to produce large numbers of high quality seeds ‘on demand’ (i.e. all year long) is a primary requirement for the successful development of aquaculture. This relies on optimal broodstock management practices based on extensive knowledge of the nutritional and environmental requirements of fish in captivity. However, for many established, emerging and new farmed fish species, such knowledge is limited or not available yet. The level of domestication also plays an essential role as stocks with improved traits in farming conditions are selected. Importantly, reliable indicators of egg quality are still lacking and hatcheries still rely on wild harvested broodstocks in many farmed fish species. These key challenges must be addressed urgently to ensure the sustainable development of the European fish farming sector. This review gives an overview of methods to assess egg/sperm quality and many of the most important factors affecting gamete production and quality, including broodstock nutrition, environmental and spawning induction protocols, genetic management, gamete preservation and new reproductive strategies.

A review of the nutrition and feeding management of farmed tilapia throughout the culture cycle

Abstract: Tilapia is the second most farmed fish group worldwide and over the past decade has quadrupled in production, largely due to their many characteristics conducive to aquaculture conditions as well as to the high marketability and relatively stable market prices. To keep pace with this rapid expansion, tilapia aquaculture will rely increasingly on more sustainable practices, but this must not be at the expense of decreased productivity, increased cost or compromised product quality. Since feed constitutes the major operating cost of tilapia farming, understanding their nutritional requirements, factors that may influence these requirements and implementing the most appropriate feeding management strategy is essential for the continued sustainability and scalability of the global tilapia industry. This review addressed these concerns by providing an overview of published nutrient requirement data and offered practical recommendations to the nutrition and feeding management of farmed tilapia, from broodstock to finishing feeds. The first section of this review extensively discusses the dietary protein/amino acids, lipids/fatty acids, carbohydrates, vitamin and mineral requirements of tilapia. Alternatives to marine-based ingredients, which are used increasingly in tilapia feeds, are also discussed. This is followed by discussing practical feed management aspects at the commercial farm level including feed formulations, feed types and feeding rates/frequency throughout the culture cycle. Recent research indicating significant differences in nutrient requirements and utilization efficiencies of improved tilapia strains versus non-improved strains are highlighted. This review aims to provide a comprehensive overview of tilapia nutrition and thus contributes to the continued global expansion of tilapia farming and the demand for their products.

Microbiology and immunology of fish larvae

Abstract: For most marine aquaculture species, one of the main bottlenecks is the stable production of high quality juveniles. The high and unpredictable mortality in the first weeks after hatching of marine fish larvae remains a challenging problem that needs to be solved. The severity of the problem differs between species, but cannot be considered adequately solved for any species. Both scientific evidence and experience in hatcheries for a variety of fish, shrimp and shellfish species are accumulating as support for the hypothesis that detrimental fish-microbe interactions are the cause of these problems. Host-microbe interactions in reared fish are still poorly understood, except for a few pathogens, and empirical data of the quality required to test this hypothesis, are lacking. This article provides an overview on the current knowledge of the microbial environment of fish larvae, including methodological aspects to characterize the microbial community (both using culture-dependent and culture-independent methods). Further, the current knowledge of the immunology of fish larvae is reviewed, including recent advances in the understanding of toll-like receptors, inflammatory cytokines, mast cells and piscidins, and the ontogeny of the adaptive immune system. Finally, we provide an overview of the state of the art with respect to steering of microbial communities associated with fish larvae - both steering of community composition and of its activity (e.g. by quorum sensing interference).

What determines growth potential and juvenile quality of farmed fish species

Abstract: Enhanced production of high quality and healthy fry is a key target for a successful and competitive expansion of the aquaculture industry. Although large quantities of fish larvae are produced, survival rates are often low or highly variable and growth potential is in most cases not fully exploited, indicating significant gaps in our knowledge concerning optimal nutritional and culture conditions. Understanding the mechanisms that control early development and muscle growth are critical for the identification of time windows in development that introduce growth variation, and improve the viability and quality of juveniles. This literature review of the current state of knowledge aims to provide a framework for a better understanding of fish skeletal muscle ontogeny, and its impact on larval and juvenile quality as broadly defined. It focuses on fundamental biological knowledge relevant to larval phenotype and quality and, in particular, on the factors affecting the development of skeletal muscle. It also discusses the available methodologies to assess growth and larvae/juvenile quality, identifies gaps in knowledge and suggests future research directions. The focus is primarily on the major farmed non-salmonid fish species in Europe that include gilthead sea bream, European sea bass, turbot, Atlantic cod, Senegalese sole and Atlantic halibut.

Salmon Welfare Index Model (SWIM 1.0): a semantic model for overall welfare assessment of caged Atlantic salmon: review of the selected welfare indicators and model presentation

Abstract: A semantic model for overall welfare assessment of Atlantic salmon reared in sea cages is presented. The model, called SWIM 1.0, is designed to enable fish farmers to make a formal and standardized assessment of fish welfare using a set of selected welfare indicators. In order to cover all welfare relevant aspects from the animals’ point of view and to create a science-based tool we first identified the known welfare needs of Atlantic salmon in sea cages and searched the literature for feasible welfare indicators. The framework of semantic modelling was used to perform a structured literature review and an evaluation of each indicator. The selected indicators were water temperature, salinity, oxygen saturation, water current, stocking density, lighting, disturbance, daily mortality rate, appetite, sea lice infestation ratio, condition factor, emaciation state, vertebral deformation, maturation stage, smoltification state, fin condition and skin condition. Selection criteria for the indicators were that they should be practical and measureable on the farm, that each indicator could be divided into levels from good to poor welfare backed up by relevant scientific literature. To estimate each indicator’s relative impact on welfare, all the indicators were weighted based on their respective literature reviews and according to weighting factors defined as part of the semantic modelling framework. This was ultimately amalgamated into an overall model that calculates welfare indexes for salmon in sea cages. More importantly, the model identifies how each indicator contributes (negatively and positively) to the overall index and hence which welfare needs are compromised or fulfilled.

Fantastically plastic: fish larvae equipped for a new world

Abstract: Teleost fish are more diverse than any other vertebrate group, and yet only a limited number of species are fished and farmed globally. Efforts to expand the quantity and diversity of fish produced are hampered by the extreme diversity of ontogenetic responses of fish, especially during larval development. This review looks at advances in molecular phylogeny, endocrine and nutrient influences and long-term studies of the phenotypes of commercially important fish to put the sources and consequences of this plasticity into context. This nested context of evolutionary forces of the fish-specific genome duplication, epigenetic influences, ontogenetically conserved processes like metamorphosis and cell determination is further presented in relation to how fish larvae translate the environment into somatic signals, the teleostian diversity of internal processes like sex differentiation and somatogenesis, and the long-term practical consequences of changes in timing or anthropogenic influences. This review aims to present a new baseline of knowledge of marine fish larvae which is useful to scientists, managers and producers.

Bioeconomics of mud crab, Scylla paramamosain, culture in Vietnam

Abstract: The results of bioeconomic analysis informed by a survey of 80 small-scale mud crab farmers in Vietnam are presented in this paper. Mud crab farming in Vietnam is profitable, with net revenue being approximately 135 and 41 million VND/year (USD 7000–USD 2100 per year) in the central and southern regions, respectively. Profitability was significantly higher in the centre compared with the north, as almost three times the biomass is harvested in the centre compared with the south (in turn, due to higher aquaculture area and survival rates). The benefit–cost ratio (the ratio between total revenue and total costs) is 3.55 in the centre and 1.97 in the south. The crabs are fed almost exclusively on low-value finfish in the centre and the south. Feeding rates were found to be low, with 95% of biomass gain coming from natural feed in the environment rather than supplementary feeding by the farmer. If pellets are to be adopted widely by mud crab farmers, negative perceptions regarding the poor adaptability of mud crab to pellets (northern farmers only), relatively slow growth rates compared with low-value finfish and lack of availability of pellets need to be overcome.

Skeletal anomalies in reared European fish larvae and juveniles. Part 1: normal and anomalous skeletogenic processes

Abstract: This critical review summarizes the knowledge about fish skeletal tissues and inherent normal and anomalous development. Particular emphasis is given to existing literature on reared European fishes. The aim was to identify the main gaps of knowledge that require to be filled, in order to precociously identify anomalous developmental patterns that lead to skeletal anomalies in reared finfish larvae and juveniles. The review also aims to extend our knowledge about the factors that are possibly involved in the onset of skeletal anomalies. The final goal is the optimization of the morphological quality of farmed juvenile fish.

Nutrient discharge from aquaculture operations in function of system design and production environment

Abstract: In aquaculture, nutrient loading is defined as the difference between nutrients supplied with fertilizers and feed and nutrients harvested in the form of finfish, crustaceans, molluscs and seaweeds. On average, the production of finfish and crustaceans results in a net nutrient loading, while for the production of molluscs and seaweeds the nutrient loading is negative. In marine and brackish water aquaculture, on a global scale, more nutrients are extracted than added to the environment. However, in freshwater, more nutrients are loaded than extracted. In 2008, the global aquaculture production of finfish and crustaceans resulted in an environmental loading of 1.7 million metric tonnes of nitrogen (N) and 0.46 million metric tonnes of phosphorus (P). This nitrogen loading represents 0.9% of the human input to the N-cycle and 0.4% of the global N-cycle. For phosphorus, the loading from finfish and crustacean aquaculture represents 2.3% of the global annual fertilizer supply. With cage aquaculture, nutrients are directly discharged to the environment. Mitigation measures should be shared equally between all polluters involved. For land-based aquaculture, the development of water re-use systems is still in its infancy. Although still a minor contributor to global aquaculture production, recirculation technology shows that control and mitigation of pollution from aquaculture is possible. A 15–20 year goal should be to have all inland aquaculture operations applying water re-use and purification technology and generating useful (waste) outputs in addition to standard aquaculture products.

Southward expansion of the Chilean salmon industry in the Patagonian Fjords: main environmental challenges

Abstract: Chile is the second largest producer of farmed salmon in the world. After reaching a peak harvest of 631 000 tonnes in 2008, a severe sanitary and production crisis triggered a major legal and operational reorganization, and an imminent expan- sion of the industry into the Aysen Fjords System (AFS). This expansion has caused increasing national and international concern about its potential negative impact upon this pristine area, which holds a mosaic of unique ecosystems and three World Biosphere Reserves. This paper reviews and provides some upper bounds to potential impacts under two feasible production scenarios. It is con- cluded that severe but highly localized mid-term damage to the sea-floor bottom may affect up to 6200 ha. Although this surface area represents only 0.5% of the AFS, the high heterogeneity and limited scientific knowledge of local ecosystems increase the risks of damaging sensitive habitats, communities or populations. While additional inputs of up to 60 000 t of nitrogen and 8000 t of phosphorus can be predicted, the estimation of carrying capacities is a pendant and urgent task to be accomplished in this area. If current escape rates are not reduced, the average number of escaped salmon may exceed 4.4 million individuals each year, able to consume up to 6600 t of pelagic prey from local ecosystems. We recom- mend following a strict precautionary approach, not granting new farming leases until sufficient information about the risk and magnitude of these impacts is obtained and transformed into effective management actions.

Genes and growth performance in crustacean species: a review of relevant genomic studies in crustaceans and other taxa

Abstract: Global aquaculture has expanded rapidly to address the increasing demand for aquatic protein needs and an uncertain future for wild fisheries. To date, however, most farmed aquatic stocks are essentially wild and little is known about their genomes or the genes that affect important economic traits in culture. Biologists have recognized that recent technological advances including next generation sequencing (NGS) have opened up the possibility of generating genome wide sequence data sets rapidly from non-model organisms at a reasonable cost. In an era when virtually any study organism can ‘go genomic’, understanding gene function and genetic effects on expressed quantitative trait locus phenotypes will be fundamental to future knowledge development. Many factors can influence the individual growth rate in target species but of particular importance in agriculture and aquaculture will be the identification and characterization of the specific gene loci that contribute important phenotypic variation to growth because the information can be applied to speed up genetic improvement programmes and to increase productivity via marker-assisted selection (MAS). While currently there is only limited genomic information available for any crustacean species, a number of putative candidate genes have been identified or implicated in growth and muscle development in some species. In an effort to stimulate increased research on the identification of growth-related genes in crustacean species, here we review the available information on: (i) associations between genes and growth reported in crustaceans, (ii) growth-related genes involved with moulting, (iii) muscle development and degradation genes involved in moulting and (iv) correlations between DNA sequences that have confirmed growth trait effects in farmed animal species used in terrestrial agriculture and related sequences in crustacean species. The information in concert can provide a foundation for increasing the rate at which knowledge about key genes affecting growth traits in crustacean species is gained.

A review and SWOT analysis of aquaculture development in Indonesia

Abstract: Indonesia has a long history of aquaculture, dating from the 15th century. Subsequently, the country has become a significant contributor to global aquaculture production, destined for both international and domestic markets. In 2009 the Government of Indonesia announced its vision to see Indonesia become the highest (volume) producer of aquaculture products in the world by 2015, with production targets equivalent to an overall increase in production of 353% between 2009 and 2014. This paper comprises a PEEST (policy, economic, environmental, social, technical) review undertaken as a background study for a SWOT (strengths, weaknesses, opportunities, threats) analysis, the outcomes of the SWOT analysis and a discussion of possible approaches to support sustainable aquaculture development in Indonesia. To meet the vision of a dramatic expansion of aquaculture production, one or more of the following strategies is required: intensification and production segmentation, areal expansion, and/or production diversification. Most likely the continued development of aquaculture in Indonesia will be a combination of these three strategies, with the relative influence of each depending on production sector and market demands. A key issue identified in the PEEST review and SWOT analysis is the dominance (in terms of number) of Indonesian aquaculture by smallholder aquaculture farmers. We argue that a range of influences, including aquaculture production expansion and changing international market requirements, have the potential to negatively impact smallholder aquaculture farmers in Indonesia, and that further policy development should specifically address these issues.

Role of life cycle assessment in sustainable aquaculture

Abstract: As an alternative food source to wild fisheries, aquaculture shows a great potential to help meet the growing demand for seafood and animal protein. The expansion of aquaculture has been achieved partly by system intensifica- tion, which has drawn vast criticisms of aquaculture for its environmental, social and economic sustainability issues. Life cycle assessment (LCA) has become the leading tool for identifying key environmental impacts of seafood production systems. A LCA evaluates the sustainability of diverse aquaculture systems quantitatively from a cradle-to-grave perspective. It provides a scien- tific basis for analysing system improvement and the development of certifica- tion and eco-labelling criteria. Current efforts focus on integrating local ecological and socio-economic impacts into the LCA framework. A LCA can play an important role in informing decision makers in order to achieve more sustainable seafood production and consumption. This article reviews recent applications of LCA in aquaculture, compares the environmental performance of different aquaculture production systems, explores the potential of including biodiversity issues into LCA analysis and examines the potential of LCA in set- ting criteria for certification and eco-labelling.

Differentiating the wild or farmed origin of Mediterranean fish: a review of tools for sea bream and sea bass

Abstract: This study was financed by the European Union 7th Research Framework Project ‘Prevent Escape’ (no 226885; wwwpreventescapeeu)

Protein, lipid and energy requirements of cultured marine fish in cold, temperate and warm water

Abstract: Temperature is one of the most important physical factors influencing fish growth. Under optimal temperatures, food energy partitioned into fish growth can be maximized. However, when a marine carnivorous species is cultured in an environment where temperature falls outside the optimal range of a fish, growth will be affected. The nutrient–environment interaction is important for optimizing a fish’s nutritional requirements throughout the grow-out period. The most current global issue for the aquaculture industry is the inclusion of alternative ingredients into formulated diets to produce a sustainable seafood product. This requires the substitution of fish meal and fish oil with alternative ingredients from plant and terrestrial animal sources. This review discusses the changes in nutritional requirements (protein, lipid and energy) and physiology of some commonly cultured marine fishes as a consequence of seasonal changes in temperature during the grow-out period. This review also discusses the effects of replacing fish meal and fish oil with alternative protein and lipid sources on the nutritional–environmental interactions of fish performance at different temperatures.

Sustainability issues related to feeding salmonids: a Canadian perspective

Abstract: The issue of sustainability of salmonid culture has been the focus of considerable media coverage and debate between environmental activists and aquaculture industry stakeholders, particularly regarding the use of ingredients derived from wild fisheries (fishmeal and fish oil) in salmonid feeds. This study attempts to summarize recent data and to calculate the conversion efficiency of feed resources by Canadian farmed salmon in order objectively to assess the sustainability of this industry in this regard. Using updated information regarding domestic aquafeeds this review reports advances that have been made in diet formulation, fish in-fish out (FIFO) and feed conversion ratios (FCR) and demonstrates that production efficiency of farmed salmonids has significantly improved over time due to continued innovations in the aquafeed sector. The results suggest that the Canadian salmon aquaculture industry efficiently converts wild fish resources into high-value fish products.

Economic risk associated with white spot disease and stochastic variability in economic, zootechnical and water quality parameters for intensive production of Litopenaeus vannamei

Abstract: A bio-economic model was used to analyse the risks of intensive production of shrimp and to propose alternative schemes of risk management by controlling aeration, pond size, stocking density and duration of cultivation. The model was calibrated from databases of farm operations in the State of Nayarit, Mexico. Improving management allowed us to project an increase in the annual net revenue from $3900 to $26 600 ha � 1 and to improve the benefit–cost ratio from 1.14 to 1.55. Managing an early start of aeration, small-sized ponds, high stocking densities and long cultivation periods maximized economic outcomes. Operating a small farm (consisting of a single 2.5 ha pond) involves more risk than operating a large one (50 ha, consisting of 20 ponds of 2.5 ha each). Improving management also resulted in diminished risk, as indicated by increased values of return per unit risk from 0.14 to 0.21 or from 0.42 to 0.51 (depending on farm size). From sensitivity analysis, we concluded that small ponds are recommended for intensive production of Litopenaeus vannamei and that white spot disease is a major risk factor that can be partly controlled by managing dissolved oxygen levels and aeration.

Moult inhibiting hormone: a new approach to the discovery and design of growth promoters in crustaceans?

Abstract: Several chemicals have been tested as growth promoters in aquaculture but they cannot be endorsed for commercial processes due to their residual effects in the body of prawns, lobsters and crabs. The concern over environmental hazard, human health and food safety have led to a search for alternative growth promoters significantly to improve the growth of crustaceans with no such effects. Neurohormones, regulatory signalling molecules of crustaceans that coordinate multiple developmental and physiological processes, are major determinants underlying phenotypic integration. Competitive inhibitors for the moult inhibiting hormone receptor are expected to have a direct growth promoting effect on crustaceans by direct involvement in interference with the receptor in the Y-organ, which can cause a surge the production of ecdysteroids. Competitive inhibitors therefore can be regarded as growth promoters in crustacean fishery in addition to various other benefits. This review emphasizes the manifold effects of moult inhibiting hormone, a most versatile animal hormone, with an emphasis on the target sites and competitive inhibition.

Selectivity of particle size by the pink shrimp Farfantepenaeus duorarum (Burkenroad, 1939) larvae

Abstract: Artificial foods have been proposed in aquaculture as a complement or substitute for live food and the quality has been evaluated by considering nutritional value, acceptability, digestibility and water stability, but because of the filterfeeding behaviour of larvae of the cultured shrimp and the diversity of food found in the market for larviculture, it is important to define the size of food ingested by the different larval stages until the postlarval stage where raptorial habits are more evident than the filter feeding lifestyle. Selectivity assays in the pink shrimp Farfantepenaeus duorarum larvae were made using polystyrene DVB particles with a diameter between 1 and 50 lm as food. A group of organisms between zoea I and postlarval I stages were put into the particle suspension for 15 min to let the particles be ingested. The particle distribution in the medium and the content of the gut of the animals were characterized with digital-image processing analysis. The results were compared using the Ivlev selectivity formula, which contrasts the frequency distribution of each particle size in the medium and in the gut of larvae. The results of selectivity were adjusted with a third-order polynomial regression to determine the optimum and the preferred size of the food for each larval stage. The optimum sizes of the food ingested for the different stages of F. duorarum were between 6.17 and 12.02 lm and the preferred were found to be between 2.68 and 18.65 lm.