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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.

    Author(s):
  • 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.

    Author(s): John Moehl , Matthias Halwart, Randall Brummett
  • Fish meal has been used for a long time as the main protein source for animal feeds used in aquaculture. Unfortunately, this practice exerts pressure on wild fish resources. In addition, the price of fish meal is in continuous increase. Thus, it is imperative to replace fish meal by plant protein sources to ensure the sustainable success of commercial aquaculture operations. The aim of the present work was to assess the effect of replacing fish meal protein with safflower meal (SFM) on survival, growth, proximate composition, feed efficiency and protein efficiency of the marine herbivore Siganus rivulatus. For that purpose, five experimental diets were formulated with an increasing replacement of fishmeal by safflower meal. The percentages of fishmeal replacement were 0, 25, 50, 75 and 100 % for D1, D2, D3, D4 and D5 respectively. Groups of fifteen size sorted fish were stocked in each of fifteen aquaria. Fish were fed at 5% body weight three times daily. Weight gain, specific growth rate, feed efficiency ratio and protein efficiency ratio significantly decreased as the proportion of SFM increased with 100% SFM inclusion resulting in the least growth among treatments. The results showed no significant effect of SFM inclusion on viscerosomatic index, whole body protein, body ash and packed cell volume while Hepatosomatic index and lipid content were significantly different among the five treatments. In conclusion, the replacement of fish meal by safflower meal in the diets of Siganus rivulatus led to decreased growth performance and hence it is not suitable to replace fish meal by safflower meal in the diets of this marine herbivore.

    Author(s): NISRINE ALI ASSAF
  • Production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. This could replace fossil fuel-derived energy and reduce its environmental impacts, including global warming and acid rain. Although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through regulations, carbon taxes, and subsidies of biomass energy would make it cost competitive. Methane derived from anaerobic digestion is competitive in efficiencies and costs with other biomass energy forms including heat, synthesis gases, and ethanol. The objective of this paper is to review the results and conclusions of research on biomass energy conducted under the sponsorship of the gas industry with periodic co-funding from other agencies. The scope of this program was to determine the technical and economic feasibility of production of substitute natural gas (SNG) from marine and terrestrial biomass and organic wastes using anaerobic digestion as a conversion process. This work began in 1968 and continued until about 1990, ending as a result of low energy prices in the U.S. and reduced emphasis on renewable energy. For each of these feedstock categories, growth or collection (in the case of wastes), harvesting, conversion by anaerobic digestion, and systems and economic analysis were addressed. More recently the potential use of anaerobic digestion for stabilization and recovery of nutrients from solid wastes during space missions was studied with funding from NASA. The application of this process for that function as well as treatment of wastewater and waste gases generated during space missions is addressed.

    Author(s): Renewable Biomethane from Land and Ocean Energy Crops and Organic Wastes
  • The experiment shows that the seaweeds Gracilaria sp. can be used in maintaining water quality in closed culture systems by ready uptake of nitrogenous wastes excreted by the cultured organisms. The advantages of water reuse systems incorporating biological agents such as seaweeds for water management in closed systems.

    Author(s): Radhakrishnan, E V
  • The green seaweed Ulva reticulata used as co-culture species for monitoring the changes in toxic nitrogenous wastes in the shrimp culture system was found to efficiently remove ammonical nitrogen from 249.5 to 17.39 pmol nitrogen11 (94%). The nitrate nitrogen reduced from 28.39 to 24.21 pmol nitrogen 11 (5%) and nitrite nitrogen from 14.51 to 9.03 pmol nitrogen11 (22 %). The removal of total nitrogen from the aquaculture system was found to be 45 % when treated with seaweed. The concentration of toxic nitrogenous wastes was found to be always at a lower level in the integrated system when compared to the monoculture system. Seaweeds of economical importance can be used in aquaculture system to improve water quality and generate revenue for the industry.

    Author(s): Seema, C , Jayasankar, Reeta
  • This short presentation will provide an overview of the regulation of the UK and Norwegian seaweed industry.

    Author(s): Dr. Tim Atack , Dr. Jon Dunningham
  • Cultivation of Laminaria saccharina (Linnaeus) Lamouroux and Palmaria palmata (Linnaeus) Kuntze was trialled at three fish farm sites in north-west Scotland. Results show that seasonal yields of L. saccharina were enhanced by 50 % and P. palmata by 63 % when cultured adjacent to fish farm cages compared to environmentally similar sites away from the farms. Yields of P. palmata were further enhanced under conditions of optimal water movement.

    Ammonium concentrations in the seawater 0 to 50m away from the fish cages were found to be 2 - 3 μM greater than ambient. Enhanced concentrations of ammonium could be detected 200 to 300 m from the cages although the distribution is heavily influenced by local hydrography.

    Nitrogen content of L. saccharina and P. palmata cultured adjacent to the salmon cages in summer was higher than in seaweeds cultured at reference sites away from fish cages.

    Stable nitrogen isotope analysis indicates that the nitrogen in seaweeds grown next to salmon cages is derived from the fish farm and farm derived nitrogen is likely to be widely dispersed in the lochs where cages are situated.

    A preliminary economic analysis showed that growing seaweeds commercially, in particular P. palmata, may be at worst cost neutral, with profitability increasing as a result of enhanced production through increased nutrient availability adjacent to fish farms. A one hectare seaweed farm producing 600 tonnes wet weight over two years (300 tonnes per year) of P. palmata could potentially absorb up to 30 % of nutrients generated from a 500 tonnes salmon production unit.

    As farm origin nitrogen is evident in biota at distances of up to one kilometre away from the cages, cultured macroalgae would not have to be sited close to cages to result in net nitrogen removal facilitating the siting of algal farms in areas more suited for individual species requirements while still maintaining bioremediation benefits. 

    Author(s): John Craig Sanderson
  • The red macroalgae (seaweed) Asparagopsis spp. has shown to reduce ruminant enteric methane (CH4) production up to 99% in vitro. The objective of this study was to determine the effect of Asparagopsis taxiformis on CH4 production (g/day per animal), yield (g CH4/kg dry matter intake (DMI)), and intensity (g CH4/kg ADG); average daily gain (ADG; kg gain/day), feed conversion efficiency (FCE; kg ADG/kg DMI), and carcass and meat quality in growing beef steers. Twenty-one Angus-Hereford beef steers were randomly allocated to one of three treatment groups: 0% (Control), 0.25% (Low), and 0.5% (High) A. taxiformis inclusion based on organic matter intake. Steers were fed 3 diets: high, medium, and low forage total mixed ration (TMR) representing life-stage diets of growing beef steers. The Low and High treatments over 147 days reduced enteric CH4 yield 45 and 68%, respectively. However, there was an interaction between TMR type and the magnitude of CH4 yield reduction. Supplementing low forage TMR reduced CH4 yield 69.8% (P <0.01) for Low and 80% (P <0.01) for High treatments. Hydrogen (H2) yield (g H2/DMI) increased (P <0.01) 336 and 590% compared to Control for the Low and High treatments, respectively. Carbon dioxide (CO2) yield (g CO2/DMI) increased 13.7% between Control and High treatments (P = 0.03). No differences were found in ADG, carcass quality, strip loin proximate analysis and shear force, or consumer taste preferences. DMI tended to decrease 8% (P = 0.08) in the Low treatment and DMI decreased 14% (P <0.01) in the High treatment. Conversely, FCE tended to increase 7% in Low (P = 0.06) and increased 14% in High (P <0.01) treatment compared to Control. The persistent reduction of CH4 by A. taxiformis supplementation suggests that this is a viable feed additive to significantly decrease the carbon footprint of ruminant livestock and potentially increase production efficiency.

    Author(s): Ermias Kebreab, Xiang Yang, Toni L. Duarte, Rocky de Nys, Robert D. Kinley, Marielena Venegas, Breanna M. Roque
  • Production of seaweeds in Chile has fluctuated between 74,000 and 322,000 wet metric tons/year during the last 14 years, involving different species of Phaeophyta and Rhodophyta. Among Rhodophyta, the most important harvested species include the carrageenophytes Sarcothalia crispata, Mazzaella laminarioides, Gigartina skottsbergii, Chondracanthus chamissoi, and the agarophytes Gracilaria chilensis and Gelidium lingulatum. Other less important taxa are Gel. rex, M. membranacea, Ahnfeltia plicata, Ahnfeltiopsis furcellata, Porphyra columbina, Callophyllis variegata, Mastocarpus papillatusand Chondrus canaliculatus. Chilean production comes mainly from wild stocks, as at present, cultivation on a commercial scale is restricted to Gra. chilensis. Total landings of Gracilaria currently stand at 120,000 wet tons. Large-scale cultivated biomass of this species, on the other hand, has been the result of a sharp increase in the number of farms, from less than 10 in 1982 to almost 322 in 1996. A basic understanding of key biological and ecophysiological aspects, as well as the availability of propagation methods, permitted the development of large-scale Gracilaria farming operations. However, during the cultivation process, new problems arose for the farmers, such as abrupt production decline, pests and pathogens. Similar key knowledge is lacking for other Chilean Rhodophyta, which creates a bottleneck that prevents the development of seaweed farming activities other than Gracilaria. This situation prevails in spite of the growing pressure on wild stocks triggered by an increase in the demand for raw material by the industry, with the obvious danger of over-exploitation and the resulting collapse of fisheries. Taking the above into consideration, an effort has been made in recent years to provide the basic knowledge necessary for the management and cultivation of some of the most valuable seaweed resources in Chile. Thus, the main objective of this contribution is to summarize the present situation of red seaweed cultivation in the country. We will address this issue by reviewing the landing statistics of these resources, followed by a summary of recent information that favours cultivation. These include propagation methods, culture conditions and techniques, product quality, pest management, strain selection and the diversification of seaweeds currently exploited in Chile.

    Author(s): Ricardo Norambuena, María del Carmen Hernández-González, Renato Westermeier, Juan A. Correa, Alejandro H. Buschmann

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