The aim of the presented investigation was to test the sensibility of macroalgal aquaculture in offshore wind farms in the North Sea and to find arguments for the choice of appropriate sites among the planned wind farms. Based on experience with an offshore aquaculture farm of Laminaria saccharina conducted in 2002, we assessed the maximum hydrodynamic forces affecting farmed algae by applying the model software bWaveLoadQ. Drag measured in a towing tank was considerably higher on algae with a more ruffled margin and wider blade collected from sheltered environments than on flat and narrow farmed Laminaria despite comparable blade areas. Drag varied according to frond size, current velocity and acceleration reaction. Dislodgement of laminarian holdfasts and the forces necessary to break the stipe depended on blade length and surface area. Neither did our measured nor our calculated values of drag exceed those forces, provided the algae had been grown in a current N1ms1 . Even in storm conditions with maximum current velocities of 1.52 m s1 and wave heights of up to 6.4 m can cultivated L. saccharina withstand the high energy environment.
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Seaweed aquaculture is a rapidly growing component of marine food production, but the capacity to control seaweed growth lacks behind that of land agriculture. Seaweed growth requires nutrients, acquired from dissolved pools through their fronds, and light, and, as such may also be density-dependent, but general relationships between seaweed growth, nutrient concentration and incident irradiance are not yet available. We used a dataset of 1729 experimental assessments of seaweed specific growth rates and density under various nutrient and irradiance levels retrieved from the published literature to examine the relationship between seaweed growth, density, irradiance, and nutrient concentration. This analysis confirmed strong density-dependence of seaweed specific growth rates, and further confirmed that nutrient and irradiance limitation strongly impose density-dependent seaweed growth. These findings demonstrate that nutrient and irradiance limitation modulate density-dependent seaweed growth, and can help maximize growth rates in seaweed aquaculture, a rapidly growing component of global aquaculture production, by manipulating stocking density where nutrients are scarce and/or underwater light penetration poor.
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The importance of seaweeds as a marine resource has recently been emphasized due to the increasing demand for them as food and raw materials in the manufacture of industrial colloids, e.g. agars, carrageenan, and alginates which find varied uses in industries. In addition, the production of seaweeds through culture is now recognized as a very productive alternative source of livelihood and employment especially in developing countries in tropical Asia where a large portion of the shallow coastal fishery resources have been or are being depleted. With some exception, the present seaweed production in the tropics comes from the harvesting of wild stocks which if not regulated can result to the depletion of these stocks. Thus, it is necessary that culture and management of local stocks should be developed for the economic species to enhance and maintain their productivity.
The farming and gathering of economic species of seaweeds are labour-intensive form of activities which can help increase employment opportunities among the coastal communities and thus play an important role in enhancing their socio-economic conditions. The general ecology and productivity of shallow subtidal areas have been shown to greatly improve upon the introduction of seaweed farming. Additionally, the introduction of a management scheme for the gathering of local stocks shall also help conserve them.
The training of fishery extension workers, farm managers, and future seaweed farmers in the practical methods of culturing economic speices on Eucheuma, Gracilaria and Caulerpa, will promote further expansion of seaweed farming; on the inventory and assessment of local stocks of useful seaweeds shall promote and enhance the productivity and conservation of these species. It is for these reasons that this regional training was organized and implemented.
This training course was designed to develop and promote qualified expertise in seaweed farming to help in food production, provide cash crops and open new alternative employment to enhance the socio-economic welfare of coastal communities as well as offer practical training on seaweed farming and management of natural stocks of economically important seaweed species; improve technical knowledge about seaweeds and acquire practical skills in seaweed farming techniques, processing and marketing.
The course consisted of lectures and field training on the culture of Eucheuma, Caulerpa and Gracilaria, assessment and rational utilization of natural stocks of ecomomic species such as Sargassum, post-harvest and quality control of the produce and field study visits to existing farms. Basic lectures on the biology and ecology of seaweeds as well as methods on the identification and preparation of seaweed materials for research were also included as background information.
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WGEIM met at the University of Rhode Island from 24–28, April 2006. The meeting was attended by 11 members and one observer from six countries. Six terms of reference were addressed by the group and are summarised below.
The WG continued to develop a series of documents concerning risk analysis of the consequences of genetic interaction between farmed fish and conspecific wild stocks, as part of a joint project with GESAMP WG31. The documents consist of an introductory paper describing the risk analysis approach, and case studies of five non-salmonid aquaculture species (cod, halibut, sea bass, sea bream and turbot). The WG agreed that the papers were nearing the standard and completeness necessary for submission for peer reviewed publication. The WG recommended that the documents be completed intersessionally and submitted to an appropriate journal.
The WG continued to review existing (EU) legislation or proposed legislation and assess the impacts of the legislation on mariculture activities. Under the Water Framework Directive, no obvious mariculture impacts were highlighted based upon the implementation activities within the intersessional period. Proposed legislation is the European Marine Strategy (EMS), the Strategy for Sustainable Development of European Aquaculture and amendments to the EU Data Collection Regulation all of which might have some impacts on aquaculture activites. The group continued to investigate the applicability of sustainability indicators for aquaculture. SI’s are different from “impact” indicators in that they are more comprehensive, including considerations of not only environmental but also social and economic sustainability. Sustainability indices (SIs) are needed by aquaculture resource managers who must sort through large amounts of scientific information and make numerous environmental decisions. SIs offer a means to prioritize those aquaculture systems most in need of immediate management attention and allow scarce management assets to be applied in the most costeffective manner. SIs are also valuable for owners of seafood businesses who wish to procure “sustainable seafoods” for this rapidly growing consumer movement. The group considered and evaluated the current status and suitability of SIs for mariculture and selected a suite of SIs that are simple, flexible and cost effective. The group used a matrix approach that maps “sustainability trajectories” and was applied to salmon farming in New Brunswick, Canada and Norway. A number of recommendations were forthcoming from this term of reference. WGEIM will continue to refine the sustainability trajectories approach using the traffic light system of the UK and Canada and apply this example to salmon and shellfish aquaculture farming systems.
Integrated Multi-Trophic Aquaculture (IMTA) represents a global aquaculture sector of growing interest and potential development in the world. Although much of this interest has been expressed through ongoing research initiatives, there has been some movement towards commercialization through large-scale testing of these opportunities. The evolution from monoculture aquatic food production systems to integrated, multi-species systems is envisioned as a shift towards a sustainable approach, and one that has seen parallel developments occur in the terrestrial food production industries.
Results of research programs in North America and Europe would suggest that IMTA has high commercial potential, but that there are still some challenges remaining in terms of R&D, regulatory framework development, and product acceptability. Experimental and pilot-scale systems are providing growing evidence that there are low-level risks associated with contaminant transfers among Integrated Aquaculture components, and that these periodic risks are manageable in terms of husbandry practices and with appropriate regional/international regulatory requirements for seafood inspection. The legal frameworks that currently apply to the aquaculture industry, in most jurisdictions, are considered sufficiently flexible as to accommodate the development of Integrated Aquaculture systems and it is clear that the environmental, economic and social benefits associated with this sustainable approach to aquatic food production outweigh the risks.
The potential advantages and disadvantages of integrated mariculture, based on our assessment of the environmental, social and economic considerations for this sector were presented. In addition, number of information gaps were highlighted and research and development initiatives were recommended.
One of the obvious short-comings of research to date is that studies on substitution of fish meal and fish oil have been mutually exclusive. Many of the promising results from substitution of fish oils with plant oils have been due, in part, to inclusion of high levels of fish meal in the same diet. The fish meal provides some of the essential fatty acids that would have normally been provided directly by the fish oil. Although other novel sources of essential fatty acids are available, they must become more economical before they can sustain the needs of the aquaculture industry. Nevertheless, great advances in reducing, if not eliminating, the reliance upon wild fisheries resources for aquaculture feed ingredients are being made.
The primary conclusion is that during the intersession WGEIM will carry out a review and evaluation of recent advances on alternative sources of lipid and protein to fish oil and fish meal in aquafeed. It is proposed that WGEIM review a draft manuscript at the 2007 meeting that is to be submitted for publication in a peer reviewed scientific journal.
To date, the interaction of mariculture with exotic species and more specifically unintentional species introductions has received limited attention. This is despite the fact that exotic species are having significant impacts on the aquaculture industry worldwide and more particularly for the shellfish aquaculture industry.
The importance of bivalve culture in the promotion and transfer of exotic aquatic species as well as the importance of these exotic species to bivalve culture and the environment. Specifically, we focused on exotic species with an emphasis on those that become invasive and nuisance. Management implications and mitigation strategies are also addressed. It should be noted that the majority of the existing literature addresses the issues as they relate to oyster culture, probably because this appears to be the single greatest vector for all types of introductions (planned or otherwise) in bivalve aquaculture. There is little published information about other bivalve species with respect to their role as vectors for exotic species.
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In response to an increasing interest in sustainable aquaculture among governments and international donors, the Food and Agriculture Organization of the United Nations (FAO) and the WorldFish Centre undertook a review of how aquaculture is targeted in sub-Saharan Africa as a first step in the identification of appropriate extension approaches and production strategies that would suit the various technology user-groups. Representatives of senior fisheries management agencies from nine countries in the region met to discuss progress, opportunities and key constraints to aquaculture development.
Through a series of presentations, working group sessions and plenary discussions, broad consensus was achieved on the way forward for African aquaculture. In an effort to realize the goals of aquaculture, an attempt was made to develop a set of practical guidelines that can be used by national governments to insure that the major constraints are being addressed and that the major opportunities for aquaculture are capitalized upon to increase the contribution of aquaculture to food security and economic growth.
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This short presentation will provide an overview of the regulation of the UK and Norwegian seaweed industry.
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The demand in Chile for carrageenophytic algae has increased strongly during the last 3 years, with emphasis on Gigartina skottsbergii, a species representing landings of 32 438 t (wet) during 1996. Various sources of information indicate that this species is being over-exploited and therefore the development of cultivation technologies is needed to support the local carrageenan industry. In this study we summarize currently available information on laboratory, outdoor tank and open sea culture of G. skottsbergii. The results indicate that viable spores of G. skottsbergii can be obtained, mainly during winter, with germination rates of both tetraspores and carpospores, up to 40%. Germlings of G. skottsbergii were succesfully transplanted from the laboratory to outdoor tanks, where they displayed survival values higher than 80% during spring. Experimental trials in the field indicate that G. skottsbergii can be cultivated on rope systems, with tissue fragments used as inoculum. This last result suggests that regeneration from fragments is an alternative method for propagation and massive cultivation of G. skottsbergii in Chile.
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The signatories to this letter commend the JSA for its work on the National Aquaculture Research and Development Strategic Plan and agree with its vision and recognition of aquaculture as a strategic priority for the U.S. However, we suggest that recent aquaculture developments and global trends call for emphasis on a sector of marine aquaculture that is inadequately recognized in this plan. Specifically, we refer to the farming of marine macroalgae or seaweeds.
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In the coming decades, the world is going to face food-supply challenges, and aquaculture can contribute to feeding the growing world population sustainably. So why are more advancements not being made? John Forster of Forster Consulting in Washington, D.C., thinks general stagnation and regulatory smothering are suffocating offshore aquaculture’s potential. Forster talked to SeafoodSource recently about the problems, challenges and potential of offshore aquaculture.
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Macroalgae (mainly marine macroalgae, i.e. seaweeds) are considered as a very promising source for bioethanol production, because they have high carbohydrate contents, superior productivity, and wide adaptability. Macroalgae are generally grouped into three major categories: red, green, and brown algae. Each category has thousands of species, and each species possesses its unique cellular structure, biochemistry, and constitutes. Converting macroalgae to bioethanol involves pretreatment, saccharification, fermentation, and distillation; and the establishment of economic pretreatment methods is always the first key step for bioethanol production. In present, dilute-acid or alkali hydrolysis is typically used to treat macroalgal biomass. Macroalgae can be depolymerized under mild conditions as they have low lignin content. The resulting polysaccharides can be converted to ethanol through enzymatic hydrolysis, followed by adding bacteria, such as Saccharomyces cerevisiae and recombinant Escherichia coli KO11. Compared with the separate hydrolysis and fermentation process, the simultaneous saccharification and fermentation process often provided higher ethanol titer and conversion efficiency. However, the research on bioethanol production from macroalgae is still in its early stage due to both technical and economic barriers, significant amount of research and development work is needed prior to the commercialization of bioethanol manufacture from macroalgae.
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Marine Agronomy Group, CAFNRM, UH-Hilo
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