Search

The genus Ulva is globally distributed and has been thoroughly studied because of its functional biochemical composition, rapid growth rates and opportunistic features, and interest in Ulva cultivation is growing worldwide. In Europe, mostly near- and on-shore flow-through cultivation systems are used and land-based recirculating aquaculture systems (RAS) using fresh water or artificial seawater have not been developed for Ulva. While RAS provides quality control and can be located inland, maintenance costs are high. Using selected strains adapted to low-salinity could reduce seawater production costs and improve the economic feasibility. Therefore, our study assessed how salinity can be used as a tool for strain selection and optimization of functional traits. Growth rates and antioxidant activity of three species (four strains) of tubular and foliose Ulva from the NE-Atlantic and Mediterranean (foliose: Ulva lacinulata – two geographical strains, tubular: Ulva linza and Ulva flexuosa) were followed for three weeks at salinities ranging from 10 to 30 PSU. The tubular strains achieved optimal growth at a lower salinity than U. lacinulata. However, growth rates of both foliose strains were higher than of tubular strains, even at sub-optimal salinity. Therefore, U. lacinulata is a good candidate for RAS with artificial seawater, and the cost of salt can be reduced by up to 33.3% (20 PSU) without significantly reducing the growth rate of U. lacinulata. Higher antioxidant activity was achieved by reducing the salinity to 10 PSU for 10 days, suggesting that the functional traits of cultivated Ulva lacinulata can be optimized prior to harvest.

In Europe, turbot aquaculture has a high potential for sustainable production, but the low tolerance to fishmeal replacement in the diet represents a big issue. Therefore, this study investigated the effects of more sustainable feed formulations on growth and feed performance, as well as nutritional status of juvenile turbot in recirculating aquaculture systems. In a 16-week feeding trial with 20 g juvenile turbot, one control diet containing traditional fishmeal, fish oil and soy products and two experimental diets where 20% of the fishmeal was replaced either with processed animal proteins (PAP) or with terrestrial plant proteins (PLANT) were tested. Irrespective of diets, growth performance was similar between groups, whereas the feed performance was significantly reduced in fish of the PAP group compared to the control. Comparing growth, feed utilisation and biochemical parameters, the results indicate that the fish fed on PAP diet had the lowest performance. Fish fed the PLANT diet had similar feed utilisation compared to the control, whereas parameters of the nutritional status, such as condition factor, hepato-somatic index and glycogen content showed reduced levels after 16 weeks. These effects in biochemical parameters are within the physiological range and therefore not the cause of negative performance. Since growth was unaffected, the lower feed performance of fish that were fed the PAP formulation might be balanced by the cost efficient formulation in comparison to the commercial and the PLANT formulations. Present study highlights the suitability of alternative food formulation for farmed fish.

A recent publication by Belton et al. raises points for policy-makers and scientists to consider with respect to the future of aquaculture making recommendations on policies and investments in systems and areas of the world where aquaculture can contribute most. Belton et al. take an ‘us versus them’ approach separating aquaculture by economics, livelihood choices, and water salinity. They conclude “that marine finfish aquaculture in offshore environments will confront economic, biophysical, and technological limitations that hinder its growth and prevent it from contributing significantly to global food and nutrition security.” They argue that land-based freshwater aquaculture is a more favorable production strategy than ocean/marine aquaculture; they disagree with government and non-governmental organizations spatial planning efforts that add new aquaculture to existing ocean uses; they advocate for an open commons for wild fisheries as opposed to aquaculture; and they oppose ‘open ocean’ aquaculture and other types of industrial, capital-intensive, ‘carnivorous’ fish aquaculture. They discredit marine aquaculture rather than explain how all aquaculture sectors are significantly more efficient and sustainable for the future of food than nearly all land-based animal protein alternatives. As an interdisciplinary group of scientists who work in marine aquaculture, we disagree with both the biased analyses and the advocacy presented by Belton et al. Marine aquaculture is growing and is already making a significant contribution to economies and peoples worldwide. None of the concerns Belton et al. raise are new, but their stark statement that farming fish in the sea cannot ‘nourish the world’ misses the mark, and policy-makers would be wrong to follow their misinformed recommendations.

Coastal seas around the world are under increasing anthropogenic pressures due to the rapid expansion of maritime industry and coastal urbanisation. Multi-use (MU) of ocean space, meaning the use of the same space by multiple resource users, has emerged as one strategy to address spatial conflicts resulting from an increasing use density. The proposed multi-use of offshore wind farms (OWF) and mariculture (MAQ) is one of the most-researched examples of such a potentially symbiotic relationship. Two decades of public and academic discourse have produced an abundance of research regarding various facets of this particular combination. Nevertheless, the latest research projects of the EUs Horizon 2020 Research and Innovation Programme have identified a number of persistent barriers to continued multi-use development. The past and current public discourse has created a situation where technological readiness has outpaced societal readiness and the discussion is often complicated by the diversity of backgrounds and perceptions of the participants of this discourse. This study aims to dissect the common discourse on OWF and mariculture multi-use by utilising a targeted SWOT analysis approach based on stakeholder knowledge. This approach reveals two distinct narratives based around societal and economic considerations respectively. From this, we derive a set of tailor-made recommendations for policy makers and regulators as well as funding agencies, businesses and researchers.

Against the background of a drastically increased demand of marine proteins, off-bottom, bivalve aquaculture, provides significant potential for production growth when moved into more energetic marine waters. Hence, research, industry and politics are currently proposing the development of new offshore sites. The highly energetic conditions at these sites present a challenging environment for bivalve aquaculture. In this work, physical experiments of suspended bivalves provide new knowledge on the commonly used design parameters: the drag and inertia coefficients. Live bivalves and manufactured surrogate models at a 1:1 scale were tested in a towing tank as well as under waves. The drag coefficient of live blue mussels was determined to be Cd = 1.6 for Reynolds numbers between 2.3 × 104 and 1.4 × 105. The inertia coefficient obtained from the wave tests was Cm = 2.1 for Keulegan Carpenter numbers KC < 10. In a pursuit to better understand the differences between live mussels and surrogates in laboratory conditions, the analysis revealed that appropriate surrogates can be identified. A method to determine the characteristic diameter of mussel dropper lines is suggested. The results facilitate the future design of aquaculture systems in high-energy environments and allow for an integration into numerical models.

Aquaculture is projected to be a major supplier of marine proteins to large parts of the global population. This includes bivalves, which have a high potential to offset protein deficits, as they are highly adaptable to varying water temperature, salinity, desiccation, and oxygen conditions. This work is part of a two-piece contribution on novel marine aquaculture technology and details physical laboratory tests of a new cultivation system for bivalve farming called “Shellfish Tower”. The tested 1:20 model consists of a rectangular cage (2 × 2 m prototype scale) with a central buoyancy element and a height of 2 – 4 m. Testing was done in a current flume as well as a wave basin for current velocities between 0.4 – 2.2 m/s and wave heights of 1.6 to 5.0 m with periods between 5 to 14 s. The tests were conducted to prove the feasibility and functionality of this aquaculture system, which is usable for the collection and cultivation of mussel spat as well as for the grow-out of oysters, scallops, and seaweed in marine environments. Tests carried out in a current flume revealed that drag coefficients decrease with increasing current velocities, and range from Cd=0.5 to 2.5, while the mooring inclination increases from 12° to 84° with increasing flow velocity, which is highly dependant on the buoyancy related pretension. The examination of the mooring line tensions recorded in a wave basin showed that the largest values of snap-induced tension were up to 10 times that of the semi-static tension. The maximum-recorded tension on the system was 48 kN for a single and 89 kN for a double configuration, compared to non-snap tension values, which were in the range of 6 – 10 kN. The insights gathered in this study will inform the future design of aquaculture systems in high-energy environments and allow for an integration into numerical models.

This paper examines the concept of maritime multi-use as a territorial/SPATIAL governance instrument for the enhancement of sustainable development in five EU sea basins. Multi-use (MU) is expected to enhance the productivity of blue economy sectors, as well as deliver additional socio-economic benefits related to the environmental and social dimensions of sustainable development. The paper provides a definition of maritime multi-use and identifies the multi-uses with the highest potential in EU sea basins. In each sea basin, multi-use plays a different role as concerns sustainable development. For the Eastern Baltic Sea, the Mediterranean Sea and the Black Sea, the MU focus should remain on the environmental pillar of sustainable development. In the North Sea, North Atlantic and Western Baltic Sea, addressing social sustainability seems a key precondition for success of MU in enhancement of sustainable spatial development at sea. Moreover, it has been suggested to introduce MU key global strategies such as SDGs or Macroregional strategies and action plans and to supplement maritime spatial planning with sectoral incentives and educational efforts as key vehicles supporting MU. The paper concludes by identifying aspects which, in order to inform maritime spatial planning and maritime governance regarding a more conscious application of the aforementioned concept, require further investigation. Key tasks are related to: more profound evaluation of performance of policies supporting MUs, researching the impact of MU on societal goals and on the MU costs and benefits, including external ones, and finally identifying the impact of MU on the development of various sectors and regions on land.

Aquaculture development in Europe, while critical to the European Union (EU) Blue Growth strategy, has stagnated over the past decades due largely to high competition for space in the nearshore coastal zone among potential uses and the lack of clear priorities, policy, and planning at EU and national scales. Broad Marine Spatial Planning, including the designation of Allocated Zones for Aquaculture, requires spatial data at the corresponding broad spatial scale, which has not been readily available, as well as model projections to assess potential impacts of climate change. Here, daily chlorophyll-a, water temperature, salinity, and current speed outputs from a marine ecosystem model encompassing the coastal North East Atlantic, the North Sea, and the Mediterranean Sea (the pan-European POLCOMS-ERSEM model configuration) are used to drive a Dynamic Energy Budget growth model of Pacific oyster (Crassostrea gigas). Areas broadly suitable for growth were identified using threshold tolerance range masking applied using the model variables mentioned above, as well as bathymetry data. Oyster growth time series were transformed into simplified indicators that are meaningful to the industry (e.g., time to market weight) and mapped. In addition to early-century indicator maps, modelling and mapping were also carried out for two contrasting late-century climate change projections, following representative concentration pathways 4.5 and 8.5. Areas found to have good oyster growth potential now and into the future were further assessed in terms of their climate robustness (i.e., where oyster growth predictions are comparable between different future climate scenarios). Several areas within Europe were highlighted as priority areas for the development of offshore Pacific oyster cultivation, including coastal waters along the French Atlantic, the southern North Sea, and western Scotland and Ireland. A large potential growth hot spot was also identified along northwestern Africa, associated with a cool, productive upwelling coastal zone. The framework proposed here offers a flexible approach to include a large range of ecological input data, climate and ecosystem model scenarios, aquaculture-related models, species of interest, indicator types, and tolerance thresholds. Such information is suggested to be included in more extensive spatial assessments and planning, along with further socioeconomic and environmental data.

Marine aquaculture holds great promise for meeting increasing demand for healthy protein that is sustainably produced, but reaching necessary production levels will be challenging. The ecosystem approach to aquaculture is a framework for sustainable aquaculture development that prioritizes multiple-stakeholder participation and spatial planning. These types of approaches have been increasingly used to help guide sustainable, persistent, and equitable aquaculture planning, but most countries have difficulties in setting or meeting longer-term development goals. Scenario analysis (SA) for future planning uses similar approaches and can complement holistic methods, such as the ecosystem approach to aquaculture framework, by providing a temporal analogue to the spatially robust design. Here we define the SA approach to planning in aquaculture, outline how SA can benefit aquaculture planning, and review how this tool is already being used. We track the use of planning tools in the 20 International Council for the Exploration of the Sea member nations, with particular attention given to Norway’s development goals to 2050. We conclude that employing a combination of an ecosystem framework with scenario analyses may help identify the scale of development aquaculture goals over time, aid in evaluating the feasibility of the desired outcomes, and highlight potential social-ecological conflicts and trade-offs that may otherwise be overlooked., 2,277

There is an increasing need in the aquaculture industry for more sustainable and functional feed concepts for marine finfish. This study provides results for the effect of alternative feed formulations on health status, welfare parameters, sensory analysis, and growth performance in European seabass (Dicentrarchus labrax) over an 83-day feeding trial. Fish were fed twice a day with five experimental diets. A control diet (control) and four different alternative feed concepts rich in processed animal proteins (PAP), other alternative ingredients (NOPAP), and a positive (NOPAP+) and negative (PAP−) formulation were tested. All alternative formulations contained hydrolysates from aquaculture by-products and macroalgae. The results indicate that the alternative feed concepts are more sustainable alternatives compared with the commercial diet. Equally interesting, the alternative formulations did not affect the sensory analysis of the fillet quality or the animal welfare. These are increasingly important factors in aquaculture products and, accordingly, also in the formulation of new feeds. Feed concepts that are not only more sustainable in their production, have shorter transportation distances, recycle the resources (usage of by-products), and have no adverse effect on growth or welfare parameters are highly needed. Therefore, the experimental diets tested in this study are a win-win concept for future seabass aquaculture production.

One step to improve the economics of Recirculated Aquaculture Systems (RAS) is the use of the right feed. A 12-week lasting growth trial with juvenile turbot (Scophthalmus maximus) with an average initial weight of 54.4 ± 19.3 g evaluated the economic impact of choosing the best feed. Therefore, commercially available feeds recommended for turbot culture, two floating (feed 1 and feed 3) and one sinking (feed 2), were tested in a low-water exchange RAS device. Compositions of the macronutrients for the floating diets were 56.0% (protein), 12.0% (fat), 1.1% (fiber), and 10.0% (ash) for feed 1, which will be referred to as Floating 1, and 55.0% (protein), 16.0% (fat), 0.7% (fiber), and 11.0% (ash) for feed 3, which will be referred as Floating 2. The macronutrient composition of feed 2, which will be referred to as Sinking, was 50.0% (protein), 15.0% (fat), 1.4% (fiber), and 9.9% (ash). Growth performance differed significantly between feeds; the specific growth rates (SGR) ranged between 0.92% d−1 (Sinking) and 1.25% d−1 (Floating 1 and 2), resulting in a significantly higher growth rate for the floating feeds. Feed conversion ratios (FCR) were also significantly different, and Sinking showed the highest FCRs during the experiment. We assume that this was caused by the different swimming characteristics of the feeds and the foraging behavior of the fish instead of the different nutritional compositions of the diets. Including retailer prices, the feed costs per kg produced fish differed between 9.3% and 20.2%, resulting in the highest production costs for the Sinking. Therefore, finding the right feed for turbot and optimizing the feeding regime according to its requirements will improve the economic feasibility of turbot culture.

Commercially viable aquaculture of noble crayfish Astacus astacus (Linnaeus, 1758), a once plentiful food species in Europe, requires production of suitable artificial diets for optimal growth in recirculating aquaculture systems (RAS). This technique provides the opportunity to culture this species in an enclosed ecosystem which minimizes the risk of infection— resulting in high-value food products as well as high-quality juveniles for restocking purposes. In the current study, noble crayfish were fed in RAS with a commercial diet and relied on natural forage in an open pond system (OPS) for two months. Energy, lipid, and fatty acid (FA) content of available and alternative diets [Cyprinin K2 (CK2), Mytilus edulis Rafinesque, 1815, Elodea spp. Michx.) and crayfish tissue were determined. Crayfish from the pond system had significantly (P < 0.01 OPS versus all RAS treatments; Pairwise Wilcoxon) higher lipid content (8.51%) and more diverse FA composition than RAS crayfish. At least 15 partly comb...

The purpose of this study was to investigate whether meat from blue mussels (Mytilus edulis) harvested from offshore structures could be used as an alternative protein source in aquaculture fish feed for turbot (Scophthalmus maximus). Two feeding experiments with turbot were conducted in an initial experiment to test the applicability of mussel meal as a fishmeal replacement and/or supplement in turbot feed. In experiment A, the welfare, acceptance, and digestibility of feedstuff with 100%, 50% and 0% of mussel meal replacement for the fishmeal were tested for 8 weeks. In experiment B that followed, the convenience ratio of mussel meal protein in turbot feed for optimum growth was examined. Feedstuff with 25%, 10% and 0% of mussel meal were also fed for 8 (+6) weeks. Growth rates of fish were measured every 2 weeks and their health condition (liver somatic index) determined at the beginning and end of the experiments. Experiment A revealed that a replacement of fishmeal with either 100% or 50% mussel meal resulted in depressed growth (SGR: 1.31 ± 0.04 with 100% mussel meal; 1.54 ± 0.04 with 50% mussel meal; 1.71 ± 0.07 with 0% mussel meal). Experiment B revealed that a fishmeal replacement with 10% or 25% of mussel meal did not reduce growth nor did it have a negative effect on the health of the tested turbot. The study revealed that mussel meal has a high potential to serve as a supplement or as a fishmeal replacement in feed for turbot raised in aquaculture systems. Thus, its use in commercial aquaculture should be given future consideration.

Worldwide the renewable energy sector is expanding at sea to address increasing demands. Recently the race for space in heavily used areas such as the North Sea triggered the proposal of co-locating other activities such as aquaculture or fisheries with passive gears in offshore wind farms (OWFs). Our interdisciplinary approach combined a quantification of spatial overlap of activities by using Vessel Monitoring System and logbook data with a stakeholder consultation to conclude and verify on the actual feasibility of co-location. In the German Exclusive Economic Zone (EEZ) of the North Sea up to 90% of Danish and 40% of German annual gillnet fleet landings of plaice overlapped with areas where OWFs are developed. Our results indicated further that the international gillnet fishery could lose up to 50% in landings within the North Sea German EEZ when OWF areas are closed entirely for fisheries. No spatial overlap was found for UK potters targeting brown crab in the German EEZ. We further identified a number of key issues and obstacles that to date hinder an actual implementation of co-location as a measure in the marine spatial planning process: defining the legal base; implementation of safety regulations; delineation of minimum requirements for fishing vessels such as capacities, quotas, technical equipment; implementation of a licensing process; and scoping for financial subsidies to set up business. The stakeholder consultation verified the scientific findings and highlighted that all those points need to be addressed in a planning process. In the German EEZ we have shown that the socio-economic importance of spatial overlap varies within planning boundaries. Therefore we recommend an interdisciplinary bottom-up approach when scoping for suitable areas of co-location. Hence, an informed marine spatial planning process requires comprehensive and spatial explicit socio-economic viability studies factoring in also ecological effects of OWFs on target species.

Offshore wind power generation requires large areas of sea to accommodate its activities, with increasing claims for exclusive access. As a result, pressure is placed on other established maritime uses, such as commercial fisheries. The latter sector has often been taking a back seat in the thrust to move energy production offshore, thus leading to disagreements and conflicts among the different stakeholder groups. In recognition of the latter, there has been a growing international interest in exploring the combination of multiple maritime activities in the same area (multi-use; MU), including the re-instatement of fishing activities within, or in close proximity to, offshore wind farms (OWFs). We summarise local stakeholder perspectives from two sub-national case studies (East coast of Scotland and Germany's North Sea EEZ) to scope the feasibility of combining multiple uses of the sea, such as offshore wind farms and commercial fisheries. We combined a desk-based review with 15 semi-structured qualitative interviews with key knowledge holders from both industries, regulators, and academia to aggregate key results. Drivers, barriers and resulting effects (positive and negative) for potential multi-use of fisheries and OWFs are listed and ranked (57 factors in total). Factors are of economic, social, policy, legal, and technical nature. To date, in both case study areas, the offshore wind industry has shown little interest in multi-use solutions, unless clear added value is demonstrated and no risks to their operations are involved. In contrast, the commercial fishing sector is proactive towards multi-use projects and acts as a driving force for MU developments. We provide a range of management recommendations, based on stakeholder input, to support progress towards robust decision making in relation to multi-use solutions, including required policy and regulatory framework improvements, good practice guidance, empirical studies, capacity building of stakeholders and improvements of the consultation process. Our findings represent a comprehensive depiction of the current state and key stakeholder aspirations for multi-use solutions combining fisheries and OWFs. We believe that the pathways towards robust decision making in relation to multi-use solutions suggested here are transferable to other international locations.

In this work, laboratory tests with live bivalves as well as the conceptual design of additively manufactured surrogate models are presented. The overall task of this work is to develop a surrogate best fitting to the live mussels tested in accordance to the identified surface descriptor, i.e., the Abbott&ndash, Firestone Curve, and to the hydrodynamic behaviour by means of drag and inertia coefficients. To date, very few investigations have focused on loads from currents as well as waves. Therefore, tests with a towing carriage were carried out in a wave flume. A custom-made rack using mounting clamps was built to facilitate carriage-run tests with minimal delays. Blue mussels (Mytilus edulis) extracted from a site in Germany, which were kept in aerated seawater to ensure their survival for the test duration, were used. A set of preliminary results showed drag and inertia coefficients C D and C M ranging from 1.16&ndash, 3.03 and 0.25 to 1.25. To derive geometrical models of the mussel dropper lines, 3-D point clouds were prepared by means of 3-D laser scanning to obtain a realistic surface model. Centered on the 3-D point cloud, a suitable descriptor for the mass distribution over the surface was identified and three 3-D printed surrogates of the blue mussel were developed for further testing. These were evaluated regarding their fit to the original 3-D point cloud of the live blue mussels via the chosen surface descriptor.

This paper provides an overview of a number of socio-economic aspects related to bivalve aquaculture focussing on cultural services these activities provide to the culturing communities. Some direct socio-economic benefits of aquaculture in general exist through its supply of highly nutritious foods and other commercially valuable products. Additionally, it provides a variety of jobs and creates a set of income options. Yet, the question arises how to capture these in a coherent manner - what data is available and applicable to assess sustainable aquaculture in an inclusive way?

The concept of co-location of marine areas receives an increased significance in the light of sustainable development in the already heavily used offshore marine realm. Within this study, different spatial co-location scenarios for the coupling of offshore aquacultures and wind farms are evaluated in order to support efficient and sustainable marine spatial management strategies. A Geographic Information System (GIS) and multi-criteria evaluation (MCE) techniques were combined to index suitable co-sites in the German exclusive economic zone of the North Sea. The MCE was based on criteria such as temperature, salinity or oxygen. In total, 13 possible aquaculture candidates (seaweed, bivalves, fish and crustaceans) were selected for the scenario configuration. The GIS modelling framework proved to be powerful in defining potential co-location sites. The aquaculture candidate oarweed (Laminaria digitata) revealed the highest suitability scores at 10–20 m depth from April to June, followed by haddock (Melanogrammus aeglefinus) at 20–30 m depth and dulse (Palmaria palmata) and Sea belt (Saccharina latissima) at 0–10 m depth between April and June. In summary, results showed several wind farms were de facto suitable sites for aquaculture since they exhibited high suitability scores for Integrated Multi-Trophic Aquaculture (IMTA) systems combining fish species, bivalves and seaweeds. The present results illustrate how synergies may be realised between competing needs of both offshore wind energy and offshore IMTA in the German EEZ of the North Sea. This might offer guidance to stakeholders and assist decision-makers in determining the most suitable sites for pilot projects using IMTA techniques.

The North Sea has been and still is one of the most intensely used marine areas worldwide. Shipping (trade and private), the exploration/exploitation of energy resources (oil, gas and wind), fisheries and tourism compete for the scarce space (Holm et al. 2017). Especially, in German waters, resource-use conflicts rise between stakeholders.

The investigation and application of a wide range of dietary supplements, such as probiotics, prebiotic and other additives, are increasingly popular in aquaculture research and practice. To date few studies have attempted to quantify the value of commercially available additives in improving growth performance of juvenile turbot (Scophthalmus maximus) and in compensating potential growth reduction resulting from high levels of plant protein (PP) in carnivorous fish diets. Two experiments were conducted to investigate the effect of different active ingredients in diet additives on turbot. I) Five diets supplemented with (1) yeast b-glucan and mannan oligosaccharides (GM), (2) alginic acid from brown algal extracts (AC), (3) yeast nucleotides and RNA (NR), (4) potassium diformate (PDF) and (5) bacteria strains Bacillus subtilis and B. licheniformis (BS), containing fish meal (FM) as the only protein source, were fed to turbots (initial weight 48.8 g ± 5.2 g) over 112 days. II) Four diets supplemented with (1) GM, (2) AC, (3) NR and (4) BS, containing soy protein concentrate (SPC) and wheat gluten (WG) as a partial replacement of FM, were fed to turbots (initial weight 95.8 g ± 17.7 g) over 84 days. A non-supplemented FM diet (exp. I) and an FM- and PP-based diet (exp. II), respectively, were used as control diets. Diet additives did not promote additional weight gain, specific growth rate (SGR), daily feed intake (DFI) and feed conversion ratio (FCR) in turbot fed FM- or PP-based diets (p > 0.05) when compared to isocaloric control diets in both experiments. Growth of turbots fed the high FM content control diet (II) was significantly higher than all other treatments (p < 0.01). Body proximate composition, condition factor (K) and liver index (HSI) remained unaffected by additive supplementation in fish fed either FM or PP diets (p > 0.05). Results indicate that reported benefits for specific diet additives cannot be assumed to function or applied across species boundaries and age classes. In addition, dietary additive application may not be economically valid for larger animals and/or animals not exposed to specific culture-related stressors. The benefits of popular additives to high value species such as S. maximus remains to be tested under specific immune or physical stress situations and at crucial larval and early juvenile stages.

Technological solutions to increase the efficiency of spatial use can play a key role as part of the toolbox of marine spatial planning. Co-locating of multiple ocean uses can potentially increase the production and enjoyment of the ocean while limiting impacts. However, a basic precondition for co-locating or coproduction is that all parties' private incentives are aligned. We use a case study of co-locating an offshore wind energy firm and a mussel aquaculture firm to assess the incentive structure for cooperation and to demonstrate that social benefits from co-locating exist. We find that there is room for cooperation between firms based on potential cost sharing and that the demonstrated social benefits may arise without government intervention.

There is growing interest in using recirculating aquaculture systems (RAS) to produce juvenile noble crayfish, Astacus astacus (Linnaeus), a valuable and once plentiful food species in Europe, now a highly endangered species. The survival rates of early stripped eggs of A. astacus were compared across anti-fungal treatments in an artificial RAS incubation system based on a saline bath of approx. 20 – 22 mS cm -1 or 15 – 16 PSU over two different durations. Time from fertilisation to hatching was 82 days or 1191 degreedays. Low survival rates (live successfully hatched juveniles at end of experimental period) between 11.0 ± 9.5% and 26.6 ± 3.7% were obtained. Survival was significantly affected by the duration of egg bath within the saline solution with twice as high survival rates when eggs were saline-bathed once every two days for five minutes in comparison to eggs without treatment. Fungal rates were significantly affected by treating the eggs with a saline solution with infection rates decreasing from 3.7 ± 1.0% to 0.8 ± 0.5% in the ten minute saline bath treatment. Appropriately applied saline bathing can markedly improve survival of early-stripped noble crayfish eggs. However, further research is required to determine whether viable levels of hatching success can be obtained using early stripping and saline treatment.

The purpose of this study was to investigate the effectiveness of 11 different culture media for production of the free-living nematode Turbatrix aceti. Several other harvesting methods were tested in addition to mass production. A further focus was the investigation of amino acid alterations caused by the application of various media during the culture of T. aceti and two additional nematode species, Panagrellus redivivus and Caenorhabditis elegans. Finally, a cost analysis for the production of T. aceti was generated and its outcome compared to the production of conventional live feed organisms. Altogether 11 liquid culture media were tested for mass production of the nematode Turbatrix aceti using a minimum of effort in terms of labour and costs. Six harvesting methods, including filtration as well as active swimming of T. aceti were evaluated. Additional to the culture of T. aceti in four of the above-mentioned media, the nematodes P. redivivus and C. elegans were cultured on two different solid media. Cost analysis for the production of T. aceti includes those of the media, the equipment, as well as the labour costs for culture and harvest. An average density of approx. 30 × 106 ± 8.13 × 106 nematodes L−1 was achieved for T. aceti. The most efficient method (20 μm filtration) allowed harvesting 85.3 ± 2.7% of the nematodes from the medium without disturbing the particles. Lowest efficiency was achieved by combining sedimentation and filtration, accomplishing a harvest of 42.1 ± 5.8%. The amino acid profile of all three nematode species turned out to be both stable and very similar. Amino acid enrichment had little effect. The costs for producing one million T. aceti individuals ranged between 5.39 and 6.19 €, where labour costs accounted for 73 to 84% of the total production costs. In conclusion, T. aceti appears to be very robust, easy to handle, as well as cheaper to cultivate compared to other live-feed organisms. Therefore, its use in commercial aquaculture should be given future consideration.

While there is a great deal of global interest in the development of combined uses of open ocean installations, for commercial scale multi-use platforms for food and energy production and other potential applications, the transition from concept to reality has yet to come to fruition. While much is known about the economics, environmental, political and societal effects of individual production sectors, there are many unknowns and challenges with regard to economics, engineering, liability and social aspects of multi-use. Mutually agreed upon principles, such as those articulated in the Bremerhaven Declaration, and EU directives and grant funding opportunities to advance research and development indicate that progress, although measured, is being made. The development of true commercial-scale multi-use offshore platforms will require investment in demonstration projects and multi-national cooperation and collaboration across public and private sectors.

Continuously intensifying aquaculture demands reductions in pathogen infections without increased therapeutics use. A potential solution is the use of prebiotic feed additives like β-glucan and mannan oligosaccharides (MOS). This study focusses (1) on the effect of prebiotics glucan/MOS on growth and fitness of Starry flounder and (2) on the viability of Starry flounder as an aquaculture candidate (as it is considered in South Korea). Over 56- days, juvenile Starry flounder were fed with glucan/MOS enhanced diet and a control diet. Feeding behavior, growth rate, morphological and blood physiological parameters were monitored. Fish fed glucan/MOS enriched diets exhibited significantly increased growth over the experimental period (GLM, p

As we exhaust traditional natural resources upon which we have relied for decades to support economic growth, alternatives that are compatible with a resource conservation ethic, are consistent with efforts to limit greenhouse emissions to combat global climate change, and that support principles of integrated coastal management must be identified. Examples of sectors that are prime candidates for reinvention are electrical generation and seafood production. Once a major force in global economies and a symbol of its culture and character, the fishing industry has experienced major setbacks in the past half-decade. Once bountiful fisheries were decimated by overfishing and destructive fisheries practices that resulted in tremendous biomass of discarded by-catch. Severe restrictions on landings and effort that have been implemented to allow stocks to recover have had tremendous impact on the economy of coastal communities. During the period of decline and stagnation in capture fisheries, global production from aquaculture grew dramatically, and now accounts for 50% of the world’s edible seafood supply. With the convergence of environmental and aesthetic concerns, aquaculture, which was already competing for space with other more established and accepted uses, is having an increasingly difficult time expanding in nearshore waters. Given the constraints on expansion of current methods of production, it is clear that alternative approaches are needed in order for the marine aquaculture sector to make a meaningful contribution to global seafood supply. Farming in offshore marine waters has been identified as one potential option for increasing seafood production and has been a focus of international attention for more than a decade. Though there are technical challenges for farming in the frequently hostile open ocean environment, there is sufficient rationale for pursuing the development of offshore farming. Favorable features of open ocean waters include ample space for expansion, tremendous carrying and assimilative capacity, reduced conflict with many user groups, lower exposure to human sources of pollution, the potential to reduce some of the negative environmental impacts of coastal fish farming (Ryan 2004; Buck 2004; Helsley and Kim 2005; Ward et al. 2006; Langan 2007), and optimal environmental conditions for a wide variety of marine species (Ostrowski and Helsley 2003; Ryan 2004; Howell et al. 2006; Benetti et al. 2006; Langan and Horton 2003). Those features, coupled with advances in farming technology (Fredheim and Langan 2009) would seem to present an excellent opportunity for growth, however, development in offshore waters has been measured. This has been due in large part to the spill over from the opposition to nearshore marine farming and the lack of a regulatory framework for permitting, siting and managing industry development. Without legal access to favorable sites and a “social license” to operate without undue regulatory hardship, it will be difficult for open ocean aquaculture to realize its true potential. Some parallels can be drawn between ocean aquaculture and electricity generation. Continued reliance on traditional methods of production, which for electricity means fossil fuels, is environmentally and economically unsustainable. There is appropriate technology available to both sectors, and most would agree that securing our energy and seafood futures are in the collective national interest. The most advanced and proven renewable sector for ocean power generation is wind turbines, and with substantial offshore wind resources in the, one would think there would be tremendous potential for development of this sector and public support for development. The casual observer might view the ocean as a vast and barren place, with lots of space to put wind turbines and fish farms. However, if we start to map out existing human uses such as shipping lanes, pipelines, cables, LNG terminals, and fishing grounds, and add to that ecological resource areas that require some degree of protection such as whale and turtle migration routes, migratory bird flyways, spawning grounds, and sensitive habitats such as corals, the ocean begins to look like a crowed place. Therefore, when trying to locate new ocean uses, it may be worthwhile to explore possibilities for co-location of facilities, in this case wind turbines and fish and shellfish farms. While some might argue that trying to co-locate two activities that are individually controversial would be a permitting nightmare, general agreement can probably be reached that there are benefits to be gained by reducing the overall footprint of human uses in the ocean. Meeting the challenges of multi-use facilities in the open ocean will require careful analysis and planning; however, the opportunity to co-locate sustainable seafood and renewable energy production facilities is intriguing, the concept is consistent with the goals of Marine Spatial Planning and ecosystem based management, and therefore worthy of pursuit.

Most studies on multi-use concepts of aquaculture and wind farms explored cultivation feasibility of extractive species, such as seaweed or bivalves. However, recent studies also included the cultivation of crustaceans or fish culture in the vicinity of wind turbines. Consequently, new approaches combine fed and extractive species in integrated multi-trophic aquaculture (IMTA) concepts for offshore multi-use to reduce nutrient output and the overall environmental impact of aquaculture operations. In this chapter the findings of a series of mussel and oyster cultivation experiments over several seasons are presented, which were conducted at different offshore test sites in the German Bight. Sites were selected within future offshore wind farm areas for an explicit multi-use perspective. Results have demonstrated successful growth and fitness parameters of these candidates and therefore definitely proved the suitability of these bivalve extractive species for open ocean aquaculture. Another approach for multi-use in offshore wind farms is its use as marine protected area or even for reinforcement or restoration of endangered species, which need the absence of any fisheries activity for recovery. Current projects are testing this perspective for the native European oyster Ostrea edulis and the European lobster Homarus gammarus. From the technological point of view there are many options on how to connect aquaculture devices, such as longline and ring structures as well as different cage types, to the foundations as well as to install it in the centre of the free area between wind turbines. Next to the system design also experiments on drag forces originating from the aquaculture structure on the foundation and vice versa were investigated. Complementary to the biological, environmental end technical aspects, a number of studies were specifically targeted to address and include stakeholders, their attitudes, their interests and concerns over time. By this approach, the inclusion of stakeholders into the research process from its very beginning until today, co-production of knowledge could be fostered. Next to joint identification of the major impediments and concerns of offshore aquaculture under multi-use conditions, new issues and research questions were identified. Primary focus on the economic potential of aquaculture in offshore wind farms was shown for consumption mussels. The production of mussels using longline technology is sufficiently profitable even under the assumption of substantial cost increases. This is especially true, if existing capacities could be used. Last but not least, the EEZ is a special area-it is not a state territory even if a coastal state has its sovereign rights and jurisdiction. It is an area where three legal systems come together: International law, law of the European Union and national law. There are no mariculture projects in the German EEZ and no approval procedure has been completed so far. Some sites are not suitable for mariculture, especially because of nature conservation and shipping.

Aquaculture of extractive species, such as bivalves and macroalgae, already supplies a large amount of the production consumed worldwide, and further production is steadily increasing. Moving aquaculture operations off the coast as well as combining various uses at one site, commonly called multi-use aquaculture, is still in its infancy. Various projects worldwide, pioneered in Germany and later accompanied by other European projects, such as in Belgium, The Netherlands, Norway, as well as other international projects in the Republic of Korea and the USA, to name a few, started to invest in robust technologies and to investigate in system design needed that species can be farmed to market size in high energy environments. There are a few running enterprises with extractive species offshore, however, multi-use scenarios as well as offshore IMTA concepts are still on project scale. This will change soon as the demand is dramatically increasing and space is limited.

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 economics 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 multiuse, and presents case studies of research, development, and demonstration-scale installations in the US and EU.

Fast die Halfte der weltweit durch Marikultur erzeugten Biomasse sind Makroalgen. Die unterschiedlich gelierenden Bestandteile ihrer Zellwande (Hydrokolloide) werden industriell genutzt. Offensichtlicher fur den Verbraucher ist die Verwendung als Lebensmittel, z.B. die Rotalge Pyropia als Nori fur Sushi. Es wird erklart, warum diese Produkte teuer sind.

The health of cultivated blue mussels from an offshore and a nearshore sites was compared by assessing lysosomal membrane stability (LMS) and accumulations of lipofuscin and neutral lipids in the digestive glands. In addition, the condition index, parasite infestation rates, growth performance and energy status of the mussels were assessed during 10 months of sampling. Abiotic and biotic site characteristics were investigated by water analysis for each sampling cycle. Further, data of contaminant loads of the softbody and pollutant concentration of the water column, suspended particles and sediments from both sites were analysed. Results show that positive offshore effects due to dilution of contamination were not evident for all parameters analysed. Condition indices were high, and parasites were not present in offshore mussels. In contrast, the integrative health parameter LMS and growth performance were slightly, but not significantly, better in the nearshore cultivated mussels. These findings correspond with the higher contaminant concentrations in the softbodies of mussels and the water column from the offshore testing site. Both sites showed low LMS values and high accumulations of lipofuscin and neutral lipids, indicating that environmental conditions in the German Bight are generating stress for blue mussels even in the offshore areas. Exposure to fluvial transport points to a comparable probability for high contamination loads similar to nearshore areas. We therefore recommend adding a minimum salinity threshold to the definition of offshore aquaculture to exclude areas under fluvial influence.

Aquaculture production plays an increasingly important role to meet the global demand for aquatic products and expands continuously. Most mariculture organisms are produced in coastal areas, where space is scarce and user conflicts exist. For extensive cultures farming off the coast at offshore sites could be a solution to eliminate these problems and facilitate further expansion of environmentally sustainable aquaculture. The aim of this study was to examine the biological adequacy of two candidate species for ostreiculture, the Pacific oyster Crassostrea gigas and the European flat oyster Ostrea edulis . Growth rates, condition and mortality in offshore environments were investigated by transferring oyster spat of both species to 4 different sites in 2004 and 2007. Samples were taken every six to eight weeks from April to October and length, width, height and dry mass were measured as well as the Condition Index (CI = dry mass meat ∙ 100/dry mass shell) was calculated. Results show that both oyster species grow successfully in a high-energy environment. Mean growth rates are similar to those measured in individuals from coastal habitats (wild banks and cultures) and the CI shows seasonal variation in both species. The survival rate for both species was > 99% in 2007. However, in the previous trial in 2004 a high mortality rate was observed for O. edulis at one single site at the end of the experiment. Differences were observed in the increase of shell length and dry mass between sites and size classes. Taking these results into account site-selection criteria for different offshore locations are presented. We conclude that offshore cultivation of oysters will be successful if site-selection criteria are examined carefully when choosing a location for offshore aquaculture.