With continued human pressure on marine fisheries and ocean re- sources, aquaculture has become one of the most promising avenues for increasing marine fish production in the future. This review presents recent trends and future prospects for the aquaculture industry, with particular attention paid to ocean farming and carnivorous finfish species. The benefits of farming carnivorous fish have been challenged; extensive research on salmon has shown that farming such fish can have negative ecological, social, and health impacts on areas and parties vastly separated in space. Similar research is only beginning for the new carnivorous species farmed or ranched in marine environments, such as cod, halibut, and bluefin tuna. These fish have large market potential and are likely to play a defining role in the future direction of the aquaculture industry. We review the available literature on aquaculture development of carnivorous finfish species and assess its potential to relieve human pressure on marine fisheries, many of which have experienced sharp declines.
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In this paper, the different possibilities and innovations related to sustainable aquaculturein the Mediterranean area are discussed, while different maricultural methods, and the role ofIntegrated Multi-Trophic Aquaculture (IMTA) in supporting the exploitation of the ocean’s resources,are also reviewed. IMTA, and mariculture in general, when carefully planned, can be suitablefor environmental restoration and conservation purposes. Aquaculture, especially mariculture, isa sector that is progressively increasing in parallel with the increase in human needs; however,several problems still affect its development, mainly in relation to the choice of suitable sites, fodderproduction, and the impact on the surrounding environment. A current challenge that requiressuitable solutions is the implementation of IMTA. Unfortunately, some criticisms still affect thisapproach, mostly concerning the commercialization of new products such as invertebrates andseaweeds, notwithstanding their environmentally friendly character. Regarding the location of asuitable site, mariculture plans are currently displaced from inshore to offshore, with the aim ofreducing the competition for space with other human activities carried out within coastal waters.Moreover, in open water, waste loading does not appear to be a problem, but high-energy watersincrease maintenance costs. Some suggestions are given for developing sustainable mariculture inthe Mediterranean area, where IMTA is in its infancy and where the scarce nutrients that characterizeoffshore waters are not suitable for the farming of both filter feeder invertebrates and macroalgae.From the perspective of coupling mariculture activity with restoration ecology, the practices suggestedin this review concern the implementation of inshore IMTA, creating artificially controlled gardens, aswell as offshore mussel farming coupled with artificial reefs, while also hypothesizing the possibilityof the use of artificially eutrophized areas.
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In the past two decades, there has been much debate amongst industry, the state development agencies and the research institutions about the potential of the Irish seaweed sector. Seaweed gathering and processing is a traditional activity in Ireland bringing economic activity and employment to coastal communities. Ireland’s seaweed and biotechnology sector is currently worth €18 million per annum and employs 185 full time equivalent people (Morrissey et al., 2011). The potential to increase employment, exports and wealth from seaweed in Ireland was looked at by the National Seaweed Forum which was established in 1999 to join industry with research bodies, state agencies and departments to make recommendations for the future development of the industry.
One such recommendation was the development of seaweed cultivation. With this in mind, groups such as Bord Iascaigh Mhara (BIM), Taighde Mara Teo (TMT), National University Ireland Galway (NUIG) and Queen’s University Belfast (QUB) initiated seaweed cultivation trials. These early trials had varied success and allowed for experimentation and year-on-year technique improvement. Farming seaweed as opposed to simply gathering seaweed requires a thorough knowledge of seaweeds and perfect manipulation of the seaweed life cycle. Mastering this has concerned Irish seaweed researchers and industry practitioners alike over the last decade.
The Seaweed Hatchery project has focused on developing new techniques, and improving existing knowledge of seaweed cultivation. This manual is one such output of the project. The manual is offered to the industry as a guide to the hatchery techniques required to develop new aquaculture opportunities for Laminaria digitata.
As with all BIM ‘Aquaculture Explained’ manuals, it is based on the research and experiences of the group and includes both hatchery and sea trial cultivation results obtained over several years and sites. An attempt has been made to provide an easy to use document filled with practical advice for those interested in growing kelp.
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Aquaculture, especially in the Western World, is very often conducted in a monotypic manner without employing a balanced approach for long-term sustainability, which would take into consideration the assimilative capacity of the ecosystem. To develop innovative, effective and responsible practices ñ maintaining the health of coastal waters, and, consequently, of the cultured organisms ñ fed aquaculture types (e.g. finfish, shrimp) and organic or inorganic extractive aquaculture types (e.g. shellfish or seaweed) need to be integrated to avoid pronounced shifts in coastal processes. Most impact studies on aquaculture operations typically have focused on organic matter/sludge deposition. However, the inorganic output of aquaculture is presently emerging as a pressing issue as nutrification of coastal waters is a worldwide phenomenon, which has not spared the Bay of Fundy (Chopin et al. in press). Conversion, not dilution, is the solution so that the ìwastesî of one resource user become a resource (fertilizers) for the others. It can frequently be heard that the development of ìalternativeî species will reduce some of the aquaculture impacts. Unfortunately, too often ìalternative speciesî in the minds of a lot of people means ìalternative speciesÖ of fishî. Even though introducing another species of fish may add up economically in the short term, rarely does it balance energetically and environmentally in the long term. It is still fed aquaculture, with extra, unconsumed, pellets and unidirectional metabolic excretion. For a balanced ecosystem approach what is needed is a diversity of co-cultured organisms, performing different processes throughout the day and seasonally, and an estimate of the proportionate biomass of each so that their metabolic processes compensate each other.
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Aquaculture is the fastest growing food production sector in the world and has come under increasing scrutiny and criticism because of coastal pollution. Effluents' from intensive farming contain much organic matter, nitrogen compounds, phosphorus and other nutrients, makes the water unfit for aquaculture and lead to eutrophication. Macroalgae plays a vital role in controlling toxic wastes to reasonable and cultivable limits and also improves water quality. Aquaculture - management can be done effectively by integrating seaweeds into aquaculture systems. This method can be done either by stocking seaweeds along with shrimp in optimum stocking density or by recycling the water through a pond supplemented with seaweeds. In the present study an attempt has been made to find out the species of seaweed suitable for integrated farming with shrimp in brackish water tide-fed system on southwest coast and sea water in pump-fed system on southeast coast of India.
The removal of nitrogenous compounds such as ammonia, nitrate, nitrite and total nitrogen was found to be 65 to 82%, 34 to 53%, 28 to 77% and 53 to 60% respectively by seaweeds in the treatment ponds inrhen compared to the control ponds. The species of Gracilaria verrucosa, proved to be an ideal seaweed for integrated farming with shrimp in the brackishwater ponds and post monsoon period is the most favourable period for integrated farming as the growth performance of seaweed and shrimp were found to be more than the monsoon period in the tide-fed system of southeast coast of India. Eventhough the accumulation of toxic waste was less compared to southwest coast, the growth rate was comparatively lower in sea water system of southeast coast of India. G. verrucosa integrated with Enteromorpha intestinalis in optimum stocking density can reduce stress on shrimp by utilizing excess nitrogenous wastes either through bacterial mineralization or direct use by seaweeds.
In the Present context, luxuriant growth of G. verrucosa in the first year of experiment leading to harvest of 880kg was due to the heavy amount of nutrient loaded in the Pond for age long aquaculture activity, which enabled the proliferation of algal growth and maximum removal of nitrogenous load from the system. It was also observed that growth of alga in the pond was able to minimize the disease problems in shrimp.
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Aquaculture has a tradition of about 4 000 years. It began in China, possibly due to the desires of an emperor to have a constant supply of fish. It is speculated that the techniques for keeping fish in ponds originated in China with fishermen who kept their surplus catch alive temporarily in baskets submerged in rivers or small bodies of water created by damming one side of a river bed. Another possibility is that aquaculture developed from ancient practices for trapping fish, with the operations steadily improving from trapping-holding to trapping-holding-growing, and finally into complete husbandry practices (Ling, 1977).
Table 5. Possible environmental Impacts of aquaculture
Culture System
Environmental Impact
EXTENSIVE
1. Seaweed culture
May occupy formerly pristine reefs; rough weather losses; market competition; conflicts/failures, social disruption.
2. Coastal bivalve culture (mussels, oysters, clams, cockles)
Public health risks and consumer resistance (microbial diseases, red tides, industrial pollution; rough weather losses; seed shortages; market competition especially for export produce; failures, social disruption.
3. Coastal fishponds (mullets, milkfish, shrimps, tilapias)
Destruction of ecosystems, especially mangroves; increasingly non-competitive with more intensive systems; nonsustainable with high population growth; conflicts/failures, social disruption.
4. Pen and cage culture in eutrophic waters and/or rich benthos (carps, catfish, milkfish tilapias)
Exclusion of traditional fishermen; navigational hazards; conflicts, social disruption; management difficulties; wood consumption.
SEMI-INTENSIVE
1. Fresh- and brackishwater pond (shrimps and prawns, carps, catfish, milkfish, mullets, tilapias)
Freshwater: health risks to farm workers from waterborne diseases. Brackishwater: salinization/acidification of soils/aquifers. Both: market competition, especially for export produce; feed and fertilizer availability/prices; conflicts/failures, social disruption.
2. Integrated agriculture-aquaculture (rice-fish; live stock/poultry-fish; vegetables - fish and all combinations of these)
As freshwater above, plus possible consumer resistance to excreta-fed produce; competition from other users of inputs such as livestock excreta and cereal brans; toxic substances in livestock feeds (e.g., heavy metals) may accumulate in pond sediments and fish; pesticides may accumulate in fish.
3. Sewage-fish culture (waste treatment ponds; latrine wastes and septage used as pond inputs; fish cages in wastewater channels)
Possible health risks to farm workers, fish processors and consumers; consumer resistance to produce.
4. Cage and pen culture, especially in eutrophic waters or on rich benthos (carps, catfish, milkfish, tilapias)
As extensive cage and pen Systems above.
INTENSIVE
1. Freshwater, brackishwater and marine ponds (shrimps; fish, especially carnivores - catfish, snakeheads, groupers, sea bass, etc.)
Effluents/drainage high in BOD and suspended solids; market competition, especially for export product; conflicts/failures, social disruption.
2. Freshwater, brackishwater and marine cage and pen culture (finfish, especially carnivores -groupers, sea bass, etc. - but also some omnivores such as common carp)
Accumulation of anoxic sediments below cages due to fecal and waste feed build-up; market competition, especially for export produce; conflicts/failures, social disruption; consumption of wood and other materials.
3. Other - raceways, silos, tanks, etc.
Effluents/drainage high in BOD and suspended solids; many location-specific problems.
Source: Modified from Pullin, 1989
Chinese who emigrated to other Southeast Asian countries probably carried the knowledge with them and inspired the local people to take up fish farming. Brackishwater aquaculture is thought to have originated in Indonesia with the culture of milkfish and grey mullet (Ling, 1977) and must have spread to neighbouring countries like the Philippines which has been practising it for about 300 to 400 years (Baluyut, 1989).
The husbandry of fish is therefore not a new phenomenon. Ancient practices based on the modifications of natural bodies of water or wetlands to entrap young fish in enclosures until harvest, have just evolved into more systematic and scientific methods and techniques.
Other regions of the world have shorter traditions of aquaculture. In North America, it is about a century old; in Africa, aquaculture production consists almost exclusively of tilapia culture in freshwater ponds and dates back to the 1940s (UNDP/NORAD/FAO, 1987). Aquaculture development has been very recent and is just gaining momentum in Australia, New Zealand, and the Pacific Island countries (Rabanal, 1988b).
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Scientist fear that the largest and most prized species of the hardy 'opihi a uniquely Hawaiian delicacy may be essentially extinct on O'ahu, and the popluation of other limpets statewide is also on the decline. "Pupu" in Hawaiian means "snail" and in modern times it is used to mean hors d'oeuvres. Opihi were the most favored pupu traditionally.
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This volume addresses the potential for combining large-scale marine aquaculture of macroalgae, molluscs, crustaceans, and finfish, with offshore structures, primarily those associated with energy production, such as wind turbines and oil-drilling platforms. The volume offers a comprehensive overview and includes chapters on policy, science, engineering, and economic aspects to make this concept a reality. The compilation of chapters authored by internationally recognized researchers across the globe addresses the theoretical and practical aspects of multi-use, and presents case studies of research, development, and demonstration-scale installations in the US and EU.
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This overview examines the status and trends of seafood production, and the positive and negative impacts of aquaculture on biodiversity conservation. Capture fisheries have been stabilized at about 90 million metric tons since the late 1980s, whereas aquaculture increased from 12 metric tons in 1985 to 45 metric tons by 2004. Aquaculture includes species at any trophic level that are grown for domestic consumption or export.
Aquaculture has some positive impacts on biodiversity; for example, cultured seafood can reduce pressure on overexploited wild stocks, stocked organisms may enhance depleted stocks, aquaculture often boosts natural production and species diversity, and employment in aquaculture may replace more destructive resource uses. On the negative side, species that escape from aquaculture can become invasive in areas where they are nonnative, effluents from aquaculture can cause eutrophication, ecologically sensitive land may be converted for aquaculture use, aquaculture species may consume increasingly scarce fish meal, and aquaculture species may transmit diseases to wild fish. Most likely, aquaculture will continue to grow at significant rates through 2025, and will remain the most rapidly increasing food production system.
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Seaweeds have a long history of use as food, as flavouring agents, and find use in traditional folk medicine. Seaweed products range from food, feed, and dietary supplements to pharmaceuticals, and from bioenergy intermediates to materials. At present, 98% of the seaweed required by the seaweed industry is provided by five genera and only ten species. The two brown kelp seaweeds Laminaria digitata, a native Irish species, and Macrocystis pyrifera, a native New Zealand species, are not included in these eleven species, although they have been used as dietary supplements and as animal and fish feed. The properties associated with the polysaccharides and proteins from these two species have resulted in increased interest in them, enabling their use as functional foods. Improvements and optimisations in aquaculture methods and bioproduct extractions are essential to realise the commercial potential of these seaweeds. Recent advances in optimising these processes are outlined in this review, as well as potential future applications of L. digitata and, to a greater extent, M. pyrifera which, to date, has been predominately only wild-harvested. These include bio-refinery processing to produce ingredients for nutricosmetics, functional foods, cosmeceuticals, and bioplastics. Areas that currently limit the commercial potential of these two species are highlighted.
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