Forms Of Aquaculture Research Articles

Ecotoxicological sediment evaluations in marine aquaculture areas of Chile

Given its geographic characteristics, the southern Chilean fjord area is subjected to growing environmental pressure from the development of diverse forms of aquaculture (i.e., fish, algae, shellfish). The sediments accumulate substances as a natural sink, and ecotoxicology assays offer a reliable and robust proxy for sediment quality analyses. This study's objective was to establish a mid-range toxicity base line for the sediments in the region by applying a battery of non-specific ecotoxicological assays. Sediment samples (28) were collected in the channels and fjords studied during the CIMAR-Fiordos 11 cruise (July 2005). The sediments were evaluated using different species endemic to the eastern Pacific as targets: Ampelisca araucana, Tisbe longicornis, Arbacia spatuligera, and Dunaliella tertiolecta. The conditions for each assay were reported previously. Of the four species used as ecotoxicological tools, only D. tertiolecta differed significantly from the control group (negative) in terms of its growth. This difference could be attributed to nutrient enrichment. In general, we concluded that, although local changes occurred in the sediments, the mesoscale magnitude of the ecotoxicological alterations was small. Nonetheless, a surveillance program should be implemented that would allow us to follow-up and analyze the changes that are taking place in the systems on broader scales of time and space.

Habitat associations of estuarine species: Comparisons of intertidal mudflat, seagrass (Zostera marina), and oyster (Crassostrea gigas) habitats

The complexity of habitat structure created by aquatic vegetation is an important factor determining the diversity and composition of soft-sediment coastal communities. The introduction of estuarine organisms, such as oysters or other forms of aquaculture, that compete with existing forms of habitat structure, such as seagrass, may affect the availability of important habitat refugia and foraging resources for mobile estuarine fish and decapods. Fish and invertebrate communities were compared between adjacent patches of native seagrass (Zostera marina), nonnative cultured oyster (Crassostrea gigas), and unvegetated mudflat within a northeastern Pacific estuary. The composition of epibenthic meiofauna and small macrofaunal organisms, including known prey of fish and decapods, was significantly related to habitat type. Densities of these epifauna were significantly higher in structured habitat compared to unstructured mudflat. Benthic invertebrate densities were highest in seagrass. Since oyster aquaculture may provide a structural substitute for seagrass being associated with increased density and altered composition of fish and decapod prey resources relative to mudflat, it was hypothesized that this habitat might also alter habitat preferences of foraging fish and decapods. The species composition of fish and decapods was more strongly related to location within the estuary than to habitat, and fish and decapod species composition responded on a larger landscape scale than invertebrate assemblages. Fish and decapod species richness and the size of ecologically and commercially important species, such as Dungeness crab (Cancer magister), English sole (Parophrys vetulus), or lingcod (Ophiodon elongatus), were not significantly related to habitat type.

Comparison of Bacterial Presence in Biofilms on Different Materials Commonly Found in Recirculating Aquaculture Systems

Recirculating aquaculture offers an economic potential for successful fish farming requiring limited resources. However, this form of aquaculture may present a potential unacceptable health risk for the fish. Pathogenic microorganisms may be incorporated into biofilms found in aquaculture systems, causing recurring exposure to disease agents. The presence of E. colimodified to express a green fluorescent protein (GFP E. coli) was used to evaluate bacterial incorporation into biofilms in recirculating aquaculture systems. Disks of Buna-N rubber, polyvinyl chloride (PVC), chlorinated PVC, glass, fiberglass, and stainless steel disks, were placed in aquariums stocked with Nile tilapia, Oreochromis niloticus. Tanks were inoculated with a known amount of GFP E. coli and samples taken on days 1, 3, 7, and 15 post-inoculation. Within 24 hours post-inoculation bacterial presence was observed on all materials. The number of organisms decreased by day three, but remained consistent during the remaining period. There was no significant difference in bacterial presence between the different materials studied. This study demonstrated that bacteria can become incorporated into a biofilm with the potential for pathogen colonization of biofilms in aquaculture systems.

Capture for culture: artificial shelters for grouper collection in SE Asia

AbstractThis paper addresses a little‐discussed relationship between wild capture and mariculture, when the latter involves grow‐out of small wild‐caught fish or invertebrates in captivity. Seafood generated in this way is typically considered to be a form of aquaculture because it is assumed that, for animals removed from the wild when natural mortality is still very high, the protection conferred by culture operations will improve survivorship and enhance production. This assumption does not necessarily, however, apply when animals are removed well past the time of early high mortality. As one example of the implications of an early life‐history phase (ELP) fishery supplying culture operations, a preliminary study was conducted on an ELP fishery supplying live reef fish, especially groupers, in Southeast Asia. Grouper culture depends on both hatchery‐produced and wild‐caught fish which are then grown out to market size. Following interest to develop grow‐out operations in Indonesia, a pilot study was conducted to determine the sizes and capture rates of species of interest to the live fish trade, and to determine the likely environmental footprint of an artificial shelter (gango) type of capture method. From the results of the 15‐month study, we drew inferences regarding the sustainability of this fishing method and requirements of space, fish and materials for a viable grow‐out operation. The results showed that gangos were unselective for either species or size. Only 1.4% of the total fish catch (by number) were target species, mainly the grouper Epinephelus coioides, and most were large (mean total length was 13.6 cm) enough to have bypassed the early high mortality phase. Moreover, there were large non‐target catches that included many food fish species too small to be useful in catches. Given the large number and area of gangos needed for a viable operation, and that many groupers captured could probably have survived to reproduce, the ecological footprint of this approach could be substantial. These results, and literature on other ELP fisheries, suggest that these may often need management, have important links to other capture fishery sectors, and require careful evaluation of potential costs and benefits before introduction or development.

Introduction to the special issue on ‘Ornamental fish’

Ornamental fish are the most valuable fisheries commodity in the world on a unit weight basis, and worldwide the export value of ornamental fish is approximately 350 million USD. Ornamental fish are raised using the same basic technologies and inputs that are used in food fish production, but ornamental fish culture has not traditionally been viewed as being a form of aquaculture. In part, this is the result of the fact that research on various aspects of ornamental fish culture has often not been published in peer-reviewed journals, but rather in books and technical magazines, or it is kept proprietary. The ornamental fish industry has made amazing progress in the areas of spawning and breeding, larval nutrition, and health management that is directly applicable to food fish production, especially of emerging species. Both the ornamental fish industry and the aquaculture community can gain much by bridging the gap between these two sectors of fish culture through exchange of information. Aquaculture Research is taking a step towards this end by publishing papers from Aquarama 2001 – Second World Conference on Ornamental Fish Aquaculture, held in Singapore. Dr Lian C. Lim and Dr Patrick Sorgeloos selected manuscripts and assisted in the editorial process for this Special Issue, and are Guest Editors for this issue.

Potential Environmental Impacts From Farming Rainbow Trout Using Inland Saline Water in Western Australia

Secondary salinisation, caused by rising water tables as a result of land clearing, has led to large areas of unproductive agricultural land in Australia. Throughout the Western Australian wheatbelt, there is interest in the culture of rainbow trout (Oncorhynchus mykiss) and other fish species using saline groundwater on salt-affected farmland. We surveyed farmers and interviewed representatives of resource management agencies, to determine potential environmental impacts associated with this form of aquaculture. Four types of culture units have been used to grow trout: farm dams, constructed ponds, natural lakes and tanks. Our analysis of their water flow characteristics suggests that dams, ponds, lakes and tanks are likely to produce qualitatively similar environmental impacts. Farmers and resource managers identified the same potential environmental impacts from inland trout farming, but their perceptions of the importance of these impacts differed. In general, farmers ranked on-farm impacts more highly than off-farm impacts, while the reverse was true for resource managers. The regulation of environmental impacts in inland saline aquaculture is complicated by the diversity of government agencies involved and by the small scale of the industry. This suggests that economic instruments, facilitated by the voluntary development and application of environmental management guidelines, might be a better management tool than regulation, but there is a need to more precisely define and internalize many of the external environmental costs.

An evaluation of tropical brush and vegetation park fisheries

Brush and vegetation parks are common features of many tropical river fisheries. Areas of branches of certain tree and bush species combined with floating vegetation are placed in shallow, sheltered water so as to attract fish. They provide cover and spawning areas for many fish species. They are particularly rich trophically because of the abundance of epiphytic organisms, boring insects and molluscs on the submerged surfaces of the wood and the root systems, and because of the enriched bottom mud caused by decay of the woody material. Yields depend on the amount of woody material used and the age of the park. The economics of their operation can be complex and larger structures rely on a high degree of social organization for their installation and fishing. Fish parks are controversial in many areas, being viewed as an extractive method of fishing, a source of siltation and creator of social inequalities. However, when properly managed very high yields per unit area can be obtained and the structures can change from simple fish attracting devices to a form of aquaculture whereby net production from a river or lake can be increased.

The solution to pollution? The value and limitations of environmental economics in guiding aquaculture development

The notable increase of aquaculture production in recent decades has in many instances been matched by growing concern for its impacts. Environmentalists, consumers and members of the general public are increasingly demanding to account for its resource use and to balance its proposed benefits with its environmental sustainability. Although conventional financial and economic analyses have demonstrated a broadly positive impact for many forms of aquaculture, including the more intensive resource‐demanding systems, the use of economic tools embracing wider measurements of social and environmental costs and benefits might provide different and possibly more critical perspectives. However, although these techniques hold promise for such analyses, their development and application in sectors such as aquaculture are as yet limited. This paper reviews the relevant issues, considers the tools and applications of environmental economics and proposes ways in which these may be more effectively be applied in strategic and local decision‐making for aquaculture development.

The solution to pollution? The value and limitations of environmental economics in guiding aquaculture development

Abstract The notable increase of aquaculture production in recent decades has in many instances been matched by growing concern for its impacts. Environmentalists, consumers and members of the general public are increasingly demanding to account for its resource use and to balance its proposed benefits with its environmental sustainability. Although conventional financial and economic analyses have demonstrated a broadly positive impact for many forms of aquaculture, including the more intensive resource‐demanding systems, the use of economic tools embracing wider measurements of social and environmental costs and benefits might provide different and possibly more critical perspectives. However, although these techniques hold promise for such analyses, their development and application in sectors such as aquaculture are as yet limited. This paper reviews the relevant issues, considers the tools and applications of environmental economics and proposes ways in which these may be more effectively be applied ...

WATERFOWL OF THE LARGE FISH POND SYSTEMS IN LITHUANIA

Abstract The aim of this paper was to provide an overview on status, abundance, distribution, habitat use of the dominant waterfowl species in large Lithuanian fish pond systems and to evaluate effects of managed temporary drainages of ponds on waterfowl. In Lithuania large fish ponds are supporting numerous species of rare breeding waterbirds, included into the national Red Data Book. Certain fish ponds are meeting criteria of the Ramsar Convention. In many areas with intensive agriculture and low carrying capacity of natural wetlands large man-made fish ponds are the key feeding, moulting and roosting sites for populations of waterfowl and shorebirds. Seasonal waterfowl assemblages in the largest fish ponds are dominated by 12 abundant species: Great Crested Grebe, Grey Heron, Cormorant, Mute Swan, Whooper Swan, White-fronted Goose, Mallard, Teal, Wigeon, Pochard, Hifted Duck and Coot. Habitat use of the dominant waterfowl species is closely related with the effects of a managed temporary drainage of ponds. New forms of aquaculture in conditions of the market economy may affect most of the key waterbirds habitats in large fish ponds. Therefore the main objective of all management activities related to important bird areas in Lithuanian fish ponds is to maintain the network of these man-made wetlands.

Prediction of surface water turnover time in coastal waters using digital bathymetric information

AbstractThis paper presents a new type of geographical information system (GIS) for scientific planning of coastal waters. One hypothesis in the work is that the morphometry of the coast plays a significant role for how the water system functions as a receiving water system, for example, as a receiver of industrial and urban pollution and in response to various forms of aquaculture. A digital technique for transferring information from standard charts into morphometric parameters expressing various characteristics of the coast has been developed. Empirical data on surface water turnover times, which are costly and demanding to determine with traditional hydrodynamic methods, has been obtained from the literature for 20 defined Swedish coastal areas. Two models for simple predictions of the median surface water turnover time, based on morphometric parameters, have been developed to exemplify the use of “morphometrical models” in expressing a coast ecological key parameter. In these models, more than 90 per cent of the variation in empirical values of surface water turnover times can be statistically explained by the topographic openness. The topographic openness describes the exposure of the coastal area towards the open sea or adjacent coastal area. The models are valid for the temperature stratified period (May–October) in areas non‐affected by tides, strong coastal currents and river inflow. The areas should also be in the size range 0.15–150 km2.

Managing eutrophication associated with aquaculture development

Some forms of aquaculture cause significant impact on the natural environment and hence there is considered to be a need to control aquaculture developments. One approach would be to predict the impact nor to development and relate the predictions to predetermined standards. Predicting the potential for eutrophication requires the quantification of the amount of soluble waste being released from fish farms; use of numerical models to predict eutrophication in terms of enhanced phytoplankton biomass; establishment of environmental quality objectives and standards. This paper discusses the second and third requirements. Predictive models ranging from empirical relationships between variables to complex ecosystem models have been developed for managing eutrophication of lakes and coastal waters. The use of different types of model are discussed in the context of aquaculture development and it is concluded that empirical models should be used by regulatory authorities as a screening tool to provide a quantitative prediction of the potential for eutrophication. The establishment of environmental quality objectives and standards should be an integral part of any framework plan for aquaculture development. It is suggested that chlorophyll, rather than dissolved nutrients is a more appropriate variable to use as a standard for eutrophication associated with the growth of phytoplanton. It is concluded that there is a requirement for scientifically based values of standards to be set for coastal waters.

Structured Aquaculture Development with a Canadian Perspective

Wild fisheries resources in Canada will be increasingly replaced or augmented by aquaculture as they diminish or encounter difficulty in satisfying market demands. Commercial forms of aquaculture still suffer from the lack of innovative policies, well-delineated strategies, and pilot-scale experimentation in operational planning. The aquaculture activities in Canada are reviewed and analyzed in this paper against a model for technological planning and social futures, and against developments elsewhere in food systems. It concludes that substantial research and experimental development effort are still needed, and that the lead time for undertaking these activities is short if risk capital is not to be jeopardized. High priorities are given in support of i) innovative policy development (resource inventories, public anticipations, etc.), ii) strategic forecasting and planning (business strategies, modular enterprise structures, marketing, disease control, a gene pool of aquatic stocks, sea-ranching, aquatic polycultures, introduction of nonindigenous species, waste utilization, etc.), and iii) commercial operations (feed formulation, brood stock selection, water reconditioning, product development, production tactics, pollution control, etc.). There is a shortage of skilled aquaculture practitioners, and a need for more highly trained scientific personnel to address themselves explicitly to aquaculture. In Canada, this industry has already begun to take on an innovative structure that makes it a model for other forms of fisheries development.