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The development of the marine renewable energy and offshore aquaculture sectors is susceptible to being affected by climate change. Consequently, for the long-term planning of these activities, a holistic view on the effects of climate change on energy resources and environmental conditions is required. Based on present climate and future climate scenario, favourable conditions for wind and wave energy exploitation and for farming six marine fish species are assessed using a suitability index over all European regional seas. Regarding available energy potential, the estimated changes in climate do not have direct impacts on the geographic distribution of potential regions for the energy industry (both wind and wave based), that is they pose no threat to this industry. Long-term changes in environmental conditions could however require adaptation of the aquaculture sector and especially of its exploitation areas. Opportunities for aquaculture expansion of the assessed species are identified. Possibilities for co-location of these activities are observed in the different climate scenarios. The evaluation of potential zones for the exploitation of marine renewable energy resources and offshore aquaculture represents a stepping-stone, useful for improving decision-making and assisting in the management of marine economies both in the short-term and in the long-term development of these sectors.

The integrated multi-trophic aquaculture also known as the “IMTA” system is one of a sustainable and eco-friendly approach among aquaculture activities. This aquaculture practice does not compromise the well-being of the natural ecosystem because of the synergistic functions of different extractive species where both inorganic and organic waste have been regulated into an optimum level. The recycling of waste within the system is the most vital strategy to alleviate the impact on the neighboring natural habitats. However, the selection and good combination of the extractive species should be considered for an efficient and effective IMTA system. Thus, this review paper investigated several extractive species used in the IMTA system. Overall studies suggest that viable extractive species of mussel, sea cucumber, sea urchins, and macroalgae carried out different strategies in converting waste from aquaculture fed-species. However, among suspension extractive species, sea cucumber showed exemplary performance in the reduction of feces of the cultured fed-species. Thus, a combination of sea-cucumber, macroalgae and finfish is highly recommended in the IMTA system.

Offshore aquaculture plays an important role in China’s marine fishery economy. The research on the extraction of offshore aquaculture areas based on remote sensing technology is of great significa...

It is important for aquaculture monitoring, scientific planning, and management to extract offshore aquaculture areas from medium-resolution remote sensing images. However, in medium-resolution images, the spectral characteristics of offshore aquaculture areas are complex, and the offshore land and seawater seriously interfere with the extraction of offshore aquaculture areas. On the other hand, in medium-resolution images, due to the relatively low image resolution, the boundaries between breeding areas are relatively fuzzy and are more likely to ‘adhere’ to each other. An improved U-Net model, including, in particular, an atrous spatial pyramid pooling (ASPP) structure and an up-sampling structure, is proposed for offshore aquaculture area extraction in this paper. The improved ASPP structure and up-sampling structure can better mine semantic information and location information, overcome the interference of other information in the image, and reduce ‘adhesion’. Based on the northeast coast of Fujian Province Sentinel-2 Multispectral Scan Imaging (MSI) image data, the offshore aquaculture area extraction was studied. Based on the improved U-Net model, the F1 score and Mean Intersection over Union (MIoU) of the classification results were 83.75% and 73.75%, respectively. The results show that, compared with several common classification methods, the improved U-Net model has a better performance. This also shows that the improved U-Net model can significantly overcome the interference of irrelevant information, identify aquaculture areas, and significantly reduce edge adhesion of aquaculture areas.

Aquaculture production has increased steadily in many tropical countries over the past few decades, although impact assessments have been frequently neglected. We investigated the impacts of an offshore barramundi fish farm on water quality in the southern-central Red Sea, a traditionally understudied tropical, oligotrophic, and semi-enclosed basin. Inorganic nutrients, particulate matter, chlorophyll-a, and heterotrophic bacteria were measured periodically over 8 months around the farm. Water down-current from the farm had, on average, more heterotrophic bacteria and chlorophyll-a than up-current (11% and 34% higher, respectively). Ratios of dissolved inorganic nitrogen:phosphorus down-current from the farm were lower than ratios up-current (mean 9.8 vs 16.0, respectively). Phosphate, inorganic nitrogen, and particulate matter showed patterns of enrichment associated with the farm after a fish feeding event. Strategies such as feed optimization and considering hydrodynamics in site selection may improve water quality for future fish farms in Saudi Arabia and other tropical countries., SI

With the growing global demand for marine products, offshore aquaculture, which enables large-scale aquaculture compared to conventional coastal aquaculture, is drawing attention. In offshore aquaculture, the occurrence of red tide due to residual food can be suppressed by the circulation of ocean currents, and the environmental load can be reduced. On the other hand, since the farmed cage is located in a remote area, there are problems such as the cost of transporting food, the storage of a large amount of food, and the management of facilities in the event of a typhoon. In addition, it is especially important to manage the environmental information in the cage in order to understand the health condition of farmed fish in remote areas. If a device that measures water quality, which is one of the environmental information, is left in the sea for a long period of time, dirt such as algae will adhere and the measurement performance will deteriorate. This time, we developed an air pressure control system that allows the water quality sensor in the sea to enter the water only when measuring, and implemented it in the observation device. This observation device enables long-term observation of various water quality data.

The waters of Weh Island, Aceh Province has potency become the area for offshore aquaculture. Offshore Floating Net Cages can be an appropriate technology in increasing the biomass cultivation in Weh Island waters. However, no feasibility study has been done. Therefore, this study aims to examine the suitability of offshore aquaculture locations in the East and South regions of Weh Island Based on Hydro-oceanography parameters. The parameters examined were water quality parameters such as temperature, brightness, pH, salinity and dissolved oxygen. In addition, we also examined the aspects of physical oceanography such as tides, currents and bathymetry. The results show that the water depth ranged from 0-57 m. The tidal type in the Weh Island waters is mixed tide prevailing semidiurnal with the tidal range of 1.9 m. The average of current speed ranged from 19.03-37.67 cm/s with the directions predominantly toward northwest and southeast. It is concluded that the water quality data show that the eastern and southern parts of Weh Island are categorized as the feasible locations for offshore aquaculture. Keywords: Sabang, Hydro-oceanography, Fisheries, Offshoreaquaculture, Floating net cages

Submersible fish cages can be submerged under the water to mitigate the negative effects that arise from severe sea conditions and improve the growing environment for the farmed fish. Thus they are increasingly applied in offshore aquaculture. To ensure both safety and economic efficiency of submersible fish cages, it is important to determine the optimum submergence depth. In this study, a series of physical model experiments were conducted to investigate the hydrodynamic performance of a submersible fish cage at various submergence depths (1/6, 1/4, 1/3, and 1/2 of the water depth as well as the floating condition for reference) with a model scale of 1:20. The results of the physical model experiment for the different depths were compared to analyze the effects of submergence depths on the mooring line tension and the movement of the floating collar. The results showed that the mooring line tension and the floating collar movement significantly attenuated with increasing submergence depth. However, the attenuation tendency became stable when the fish cage reached a certain depth. According to the results, 1/3 of water depth was determined as the optimal submergence depth of the fish cages. Deeper submergence depths showed no significant advantage from a perspective of the hydrodynamic characteristics of the fish cage. The determination of the optimum submergence depth is beneficial for the structural design and operation safety of submersible net cages.

Marine aquaculture is expanding offshore, where the environmental interactions are not yet fully understood. We performed a benthic environmental assessment of an offshore fish farm on unconsolidated sediment. The physicochemical variables showed marked changes just under the fish farm, although the structure of the community and its bioturbation potential were not influenced. Under no or minimum influence from the fish farm, the physicochemical variables, including acid-volatile sulphides and redox, were notably different to those found in unaffected coastal areas. For this reason, classifications of the environmental status based on physicochemical variables should be adapted to offshore areas. Despite the low degree of impact detected, the organic matter carrying capacity should be carefully determined to avoid environmental drawbacks in terms of fine-grained offshore sediments. Offshore aquaculture could have a lower environmental impact than other types of aquaculture located closer to the coast, but further research is needed to obtain conclusive results. This work was funded by the Office for University Cooperation for Development of the University of Alicante (CUD-05/16). C.S. is funded by the University of Alicante (Ref. UATALENTO 17–11).

Shellfish can absorb and accumulate contaminants. The consumption of shellfish could expose humans to pollutants and increase related health risk. Perchlorate (ClO4−) is a ubiquitous pollutant and could affect thyroid functions, especially for children and pregnant women. However, knowledge on the contamination of perchlorate in aquatic food such as shellfish remains limited. This study aimed to investigate the abundances of perchlorate in shellfish from South China Sea and to assess human exposure risks. A total of 178 shellfish samples from eight species were collected from offshore aquaculture waters in South China Sea. Perchlorate was detected in 99.4% of them, suggesting widespread pollution in coastal waters. Concentrations of perchlorate ranged from not detected (N.D.) to 71.5 μg kg−1, with a median value of 4.33 μg kg−1. Estimated daily intake (EDI) and hazard quotient (HQ) were used to assess human exposure dose and health risks, respectively. The HQ values were determined to be less than 1, indicating no significant health risks to local residents via shellfish consumption. To our knowledge, this is the first study to investigate perchlorate contamination in South China shellfish and assess potential human risks.

The emerging sector of offshore kelp aquaculture represents an opportunity to produce biofuel feedstock to help meet growing energy demand. Giant kelp represents an attractive aquaculture crop due to its rapid growth and production, however precision farming over large scales is required to make this crop economically viable. These demands necessitate high frequency monitoring to ensure outplant success, maximum production, and optimum quality of harvested biomass, while the long distance from shore and large necessary scales of production makes in person monitoring impractical. Remote sensing offers a practical monitoring solution and nascent imaging technologies could be leveraged to provide daily products of the kelp canopy and subsurface structures over unprecedented spatial scales. Here, we evaluate the efficacy of remote sensing from satellites and aerial and underwater autonomous vehicles as potential monitoring platforms for offshore kelp aquaculture farms. Decadal-scale analyses of the Southern California Bight showed that high offshore summertime cloud cover restricts the ability of satellite sensors to provide high frequency direct monitoring of these farms. By contrast, daily monitoring of offshore farms using sensors mounted to aerial and underwater drones seems promising. Small Unoccupied Aircraft Systems (sUAS) carrying lightweight optical sensors can provide estimates of canopy area, density, and tissue nitrogen content on the time and space scales necessary for observing changes in this highly dynamic species. Underwater color imagery can be rapidly classified using deep learning models to identify kelp outplants on a longline farm and high acoustic returns of kelp pneumatocysts from side scan sonar imagery signal an ability to monitor the subsurface development of kelp fronds. Current sensing technologies can be used to develop additional machine learning and spectral algorithms to monitor outplant health and canopy macromolecular content, however future developments in vehicle and infrastructure technologies are necessary to reduce costs and transcend operational limitations for continuous deployment in an offshore setting.

Aquaculture is expected to further improve in the future and can provide 57 percent of fish for human consumption by 2025. In Indonesia, the aquaculture sector produced 5.77% of the world total production in 2014 and increases annually by, on average, 0.62%. Prigi Bay, located in the south of east Java, is one potential area to develop sustainable aquaculture in Indonesia. This study presents numerical wave modeling to investigate the potential area for offshore aquaculture in Prigi Bay. The method used Delft3D Flow and CG WAVE model to simulate wave and current. The superimposed analysis is used to select potential areas between the results of the model and the criteria of environmental parameters. The result shows that the location which meets the aquaculture criteria is located at coordinates 8.311&deg, S&ndash, 8.322&deg, S and 111.734&deg, E&ndash, 111.747&deg, E. This site has a depth of around 18&ndash, 26 m with current velocity between 0.10 and 0.14 m/s and significant a wave height between 0.2&ndash, 0.4 m. This location is the most suitable location for aquaculture in the Prigi Bay.

At present, technological support may specifically contribute to develop and to improve the aquaculture production, and in particular the fish production in offshore pens. Estimating live-fish biomass is extremely relevant to optimize the whole growth cycle, therefore the availability of portable and reliable scale is very important. We present here the detail of a smart scale suitable to be used over a rolling and pitching ship either on lakes or seas.

Farm site selection plays a critical role in determining the productivity, environmental impact, and interactions of aquaculture activities with ecosystem services. Satellite Remote Sensing (SRS) provide spatially extensive datasets at high temporal and spatial resolution, which can be useful for aquaculture site selection. In this paper we mapped a finfish aquaculture Suitability Index (SI) applying the Spatial Multi-criteria Evaluation (SMCE) methodology. The robustness of the outcome of the SMCE was investigated using Uncertainty Analysis (UA), and in parallel we evaluate a set of alternative scenarios, aimed at minimizing the subjectivity associated with the decision process. The index is based on the outputs of eco-physiological models, which were forced using time series of sea surface temperature data, and on data concerning Significant Wave Height (SWH), distance to harbor, current sea uses, and cumulative impacts. The methodology was applied to map the suitability for farming of European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) within the Italian Economic Exclusive Zone (EEZ), under three scenarios: Blue Growth, Economic and Environment. Tyrrhenian and Ionian coastal areas were found to be more suitable, compared to the Northern Adriatic and southern Sicilian ones. In the latter, and in the western Sardinia, the index is also affected by higher uncertainty. The application presented suggests that SRS data could play a significant role in designing the Allocated Zones for Aquaculture, assisting policy makers and regulators in including aquaculture within maritime spatial planning.

Offshore aquaculture of giant kelp (Macrocystis pyrifera) has been proposed by the US Department of Energy for large scale biofuel production along the west coast of California. The Southern Californian Bight provides an ideal area for offshore kelp aquaculture as the upwelling and advection of cool, nutrient-rich waters supports the growth of vast native giant kelp populations. However, concentrations of nutrients vary greatly across space, can be limiting for kelp growth over seasonal to interannual time scales, and inputs of nutrients to surface waters may be subject to local circulation processes. Therefore, it is important to understand both the spatiotemporal variability of seawater nitrate concentrations and the appropriate scale of observation in order for offshore kelp aquaculture to be successful. Here, we use a combination of satellite sea surface temperature imagery, in situ measurements, and modeling to determine seawater nitrate fields across multiple spatial and temporal scales. We then combine this information with known giant kelp physiological traits to develop a kelp stress index (KSI) for the optimal siting of offshore kelp aquaculture over seasonal to decadal scales. Temperature to nitrate relationships were determined from in situ measurements using generalized additive models and validated with buoy data. Summer and winter relationships were significantly different, and satellite-derived products compared well to buoy validations. Surface nitrate patterns, as derived from satellite temperature products, reveal the spatial variability in nitrate concentrations, and indicate areas that that may cause nutrient stress seasonally and during the negative phase of the North Pacific Gyre Oscillation. As the spatial scale of the surface nitrate product decreased, the negative bias increased and fine scale spatial variability was lost. Similarly, the averaging of daily nitrate concentration determinations over longer time scales increased the negative bias. We found that daily, 1 km spatial resolution nitrate products were most sufficient for identifying localized upwelling and areas of consistently high surface nitrate concentrations, and that areas in the northern and western-most portions of the Southern California Bight are the most suitable for sustained offshore kelp aquaculture.

With the increasing demand for aquatic products all over the world, exploring the interactions between inshore and offshore fisheries is one of the meaningful issues to help boost yield and meet immediate protein needs. However, pollution and environmental fluctuations (fishery trading market, ocean meteorological factors) may seriously affect the optimal harvesting strategy of the interaction between inshore and offshore components of the fishery. In response to this problem, we present a stochastic inshore–offshore fishery model in a polluted environment, which incorporates harvesting efforts subjected to Levy jumps and environmental toxicant influence. By virtue of the ergodic methods, the optimal harvesting effort and maximum expectation of sustainable yields are established. Using the hairtail fisheries in the East China Sea as a case study, numerical simulations are carried out to support the theoretical results. These results show that the diffusion between inshore and offshore fisheries, Levy jumps noise and environmental toxicant input may significantly affect the optimal harvesting strategy, which can provide suggestions for effective measures to increase the aquatic products and guide harmonious development of inshore and offshore aquaculture.

Changes in fishing industry resources has long been determined by climate and its fickleness, for changes in climate directly or indirectly result in changes in the oceanic environment. In recent years, the Taiwanese government has devoted its efforts towards developing land-based aquaculture as well as offshore aquaculture. On one hand, land-based aquaculture requires heavy demand for water resources, electricity, and labor; moreover, excessive groundwater withdrawal can cause land subsidence. On the other hand, when it comes to offshore aquaculture, typhoons and the Northeast Monsoon often damage net cages used in cage aquaculture – during a cloudburst, fish in cages bump into each other, which can lead to abrasion, injuries, and even subsequent bacterial diseases. Given the above, crucial issues in fish farming include attempts to lower farming costs and reducing losses and damages.This study utilized a coastal fish farm in the Penghu Islands for experiment and implementation. Penghu is surrounded by sea and promotes solar power generation; hence, by establishing our outdoor fish farm close to the sea, we can withdraw seawater for use in our fish pond’s water circulation and subsequently reduce costs for water resources. Additionally, solar power generation significantly reduces electricity costs and can provide power for our system’s sensors. Our study relies mainly on the Internet of Things (IoT) to reduce costs and needs in labor, electricity, and water resources. Meanwhile, considering the general phenomenon of ageing population, our proposed system keeps track of all the internal and external environmental factors in each step of the farming process as well as farming indices, and then apply self-learning so that, in the future, fish farming will be freed from the need of manual operations. These indices can help resolve future issues in technology gap. This study is divided into three sections: (1) automated farming and activation of surrounding devices, (2) the monitoring system, and (3) IoT sensor design aspects including (i) base station cluster planning, (ii) adaptability routing table, and (iii) self-updating sensor programs.

As mariculture progresses offshore in the US Exclusive Economic Zone, technical and ecological challenges need to be overcome, such as the choice of suitable sites that favor the production of target species. The offshore culture of blue mussels, Mytilus edulis, is performed with submerged longlines and mussels need to withstand more motion than on coastal sites. Temperature affects the ability of the byssus to adhere to farming rope, while chlorophyll concentration provides an estimation of food availability. Together, these are important factors in predicting the suitability of offshore mussel farms. To identify suitable depth of submersion for mussel ropes in New England federal waters, historical oceanographic data of temperature and chlorophyll a from 2005 to 2012 were used. The results suggest that mussel ropes were submerged during summer to a minimum depth of 15 m in northern and a 20-m depth in southern areas of New England where temperature is at a species-optimum and phytoplankton biomass is abundant. For the site offshore Massachusetts, in situ biodeposition measurements validated predicted depth, confirming satisfactory mussel performance. Promising local areas have shallow thermoclines, such as offshore Long Island, Cape Ann and New Hampshire. Recommended depths can be adjusted to future temperature increases associated with climate change.

The aquaculture industry is being pushed into deeper waters, to accommodate the increasing demand for seafood worldwide and the lack of nearshore sites: aquaculture systems for farther, harsher conditions are now being proposed. The Blue Growth initiative by the European Union is also tuned in the same direction, with the focus being on developing ocean based resources, including energy and aquaculture, and finding synergies among them. The present work proposes a novel multi-purpose platform (MPP), by retrofitting a feed barge with a small wind turbine and energy storage system, able to provide sustainable energy to a reference offshore aquaculture farm. The requirements and constraints for such hybrid system are defined, as well as a set of keys load cases, and its performance are analysed in the frequency domain. Wave loads are modelled using linear potential theory, while from an aerodynamic point of view, only the maximum thrust at the wind turbine hub level is considered in the static stability analysis. With reference to stability criteria and dynamic analysis in frequency domain, the suitability of the proposed MPP to act as a source of feed storage and energy supply is established, showing this as a potentially suitable solution.

We have evaluated the cultivation potential of sugar kelp (Saccharina latissima) as a function of latitude and position (near- and offshore) along the Norwegian coast using a coupled 3D hydrodynamic-biogeochemical-kelp model system (SINMOD) run for four growth seasons (2012-2016). The results are spatially explicit and may be used to compare the suitability of different regions for kelp cultivation, both inshore and offshore. The simulation results were compared with growth data from kelp cultivation experiments and in situ observations on coverage of naturally growing kelp. The model demonstrated a higher production potential offshore than in inshore regions, which is mainly due to the limitations in nutrient availability caused by the stratification found along the coast. However, suitable locationsareas for kelp cultivation were also identified in areas with high vertical mixing close to the shore. The results indicate a latitudinal effect on the timing of the optimal period of growth, with the prime growth period being up to 2 months earlier in the south (58 °N) than in the north (71 °N). Although the maximum cultivation potential was similar in the six marine ecoregions in Norway (150-200 tons per unit area per year) in the six marine ecoregions in Norway, the deployment time of the cultures seems to matter significantly in the south, but less so in the north. The relevance of the results is discussed with a view towards use in decision support tools and a management context. The results are discussed, focusing on their potential significance for optimized cultivation and to support decision making towards sustainable management. The kelp cultivation potential in coastal and offshore regions of Norway

Under the influence of high-intensity human activities, the discharge of chemical pollutants in coastal waters increases progressively year by year and exceeds the marine self-purification capacity, which in turn leads to major marine ecological environmental problems such as eutrophication and excessive heavy metals in water bodies. Hence, studies on the marine environmental capacity (MEC) are the basic work for the total discharge control and water quality improvement of land-based pollutants. In the article, a three-dimensional (3D) water quality model was established based on the unstructured-grid, finite-volume, free-surface and primitive equation coastal ocean model (FVCOM). Then, the mathematical model was calibrated with the data monitored in 2013 and 2014, and the MEC of dissolved inorganic nitrogen (DIN), chemical oxygen demand (COD) and petroleum hydrocarbons (PHs) in the main rivers entering the sea was calculated using the self-purification process integration method. The results indicate that the annual MEC of DIN, COD and PHs pollutants are 3.6 × 104 t/a, 45 × 104 t/a and 0.15 × 104 t/a respectively. By comparing and analyzing the current pollution load, the reduction rates of ammonia nitrogen (NH4-N) and total nitrogen (TN) in the study area are equivalent to more than 70% of the current load into the sea while COD does not need to be reduced. Only a few river units still have surplus allocated capacity (AC) while the remaining ones need to be cut down. Consequently, the control of total pollutants emission is an urgent issue to be solved. The evaluation on MEC of coastal waters can not only provide technical support for the offshore aquaculture industries, but also provide scientific basis for the total control of terrigenous pollutants in coastal cities in Northern Jiangsu Province.

Large-scale cultivation of seaweed has become one of the most important aquaculture activities in Malaysia which may help increase farmers’ incomes as well as seaweed itself can be processed into many beneficial end products. The present location of seaweed farming selected by farmers is situated close proximity to the coastline which is between 100 and 200 m from the seashore. The unfavourable condition of sea during rough sea with high wave and high speed of current is always a problem to the farmers since this environmental condition destroys their seaweed planting lines. To avoid the above problem, especially in monsoon prone area, a thorough analysis needs to be done in order to prevent environmental load from destroying seaweed platform on its mooring line when subjected to greater stress. The main objective of this study is to perform a simulation study which will allow analysis of the best mooring system for multi-body floating seaweed farm, together with understanding of the reliability a...

The fishing platform is expected to be a sustainable method for offshore aquaculture, which can avoid fish escapes by using tanks in harsher sea state and meanwhile make use of natural water. In this paper, the flow characteristics (residence time, velocity uniformity) in a force-rolling aquaculture tank are numerically investigated and analyzed by statistical methods. Through our simulations, we find that water inlet and drainage play a limited role in accelerating water velocity magnitude when being compared with the effect of the roll. Roll accelerates the velocity magnitude of water in the tank and shortens the circulation time. For cases with different rolling angles, the magnitude of water velocity in the tank is very sensitive to the rolling angle and increases with it; for cases with different rolling periods, velocity magnitude decreases as rolling periods increase. Moreover, if the rolling period exceeds a threshold, such as 10 s in this paper, the velocity increment is tiny. The residence time of water in the tank seems insensitive to both rolling angle and period. For all simulations, there is a low-velocity region along the rolling axis in the middle of the fishing tank. The water inlet slightly affects the volume of this low-velocity zone.

The study of how fluid interacts with aquaculture cages and how it influences fish swimming behaviour has proven to be of great importance for designing offshore aquaculture cage systems. This review examines the fluid-structure interactions, between structures and organisms, within cage-based aquaculture. Using data from previous research, we list and classify aquaculture cages into net-cage and closed-cage systems. Net-cage aquaculture systems are classified with regards to their submergence, materials and aperture shapes of nets. Then, the comparison is made between the research methods used to assess the interactions between environmental loads and aquaculture cages; this comparison includes analytical studies, numerical implementations, field tests and laboratory experiments. We also provide reviews of topics such as mooring and grid systems, drag coefficients of the net panel, hydrodynamic behaviours of cage components, velocity reduction of cage array and volume reduction caused by cage deformation. In particular, fish swimming behaviour is reviewed for designing new open ocean aquaculture systems. To support the further development of aquaculture engineering and technology, statistics, tables, formulae and figures are provided.

The US Department of Energy Advanced Research Projects Agency - Energy (ARPA-E) MacroAlgae Research Inspiring Novel Energy Research (MARINER) program is encouraging technologies for the sustainable harvest of large funding research of macroalgae for biofuels at less than $80 per dry metric ton (DMT). The Ocean Forests team, led by the University of Southern Mississippi, is developing a complete managed ecosystem where nutrients are transformed and recycled. The team's designs address major bottlenecks in profitability of offshore aquaculture systems including economical moored structures that can withstand storms, efficient planting, managing and harvesting systems, and sustainable nutrient supply. The work is inspired by Lapointe [1] who reported yields of Gracilaria tikvahiae equivalent to 127 DMT per hectare per year (compared with standard aquaculture systems in the range of 20 to 40 DMT/ha/yr). This approach offers the potential for breakthrough yields for many macroalgae species. Moreover, mini-ecosystems in offshore waters create communities of macroalgae, shellfish, and penned finfish, supplemented by visiting free-range fish that can increase productivity, produce quality products, and create jobs and income for aquafarmers. Additional benefits include reduced disease in fish pens, cleaning contaminated coastal waters, and maximizing nutrient recycling. Cost projections for a successful, intensive, scaled system are competitive with current prices for fossil fuels.

This paper assesses the impact of a farm of wave energy converters on a nearby offshore aquaculture installation and on the nearshore dynamics. The coastal area targeted is Agu&ccedil, adoura, located in the north of Portugal, where the world&rsquo, s first wave farm operated in 2008. The study is focused mainly on the evaluation of the sheltering effect provided by the wave farm to the aquaculture cages. Furthermore, the possible impact on the coastal wave climate of such an energy park is also evaluated. These objectives are accomplished by performing simulations, corresponding to the wave conditions, which are more often encountered in that coastal environment. The SWAN model (Simulating WAves Nearshore) was adopted for this. Various transmission scenarios are considered to account for the impact of different types of wave converter farms on the downwave conditions. The results show that such a wave energy park might have a clear positive impact on the wave conditions fish farm installed downwave and it might also have a beneficial influence on shoreline dynamics from the perspective of coastal protection.

This paper presents an innovative tool to recognize potential zones for the development of offshore aquaculture activities from an expanded spatial perspective. The methodology — developed in the framework of the TEN-SHORES project (Development of new technologies in oceanic aquaculture RTC-2014-2485-5) — aims to identify optimal conditions for the growth of fish species and for cage resistance. The first step is based on the Delphi method and consists of the selection of variables according to their relevance to fish species and to the cage location. The selected variables were acquired from reanalysis models and remote sensing data (time series of 20–30 years). In the second step, an evaluation system was developed to estimate the percentage of time (on a 0-1 scale) that the selected variables remain in optimum conditions, for the fish and the cage, in the whole data series (grid of 0.25°). Suitability maps were generated according to the conditions for the fish species growth and to house a generic cage. The integration of these maps allows for the identification of potential zones (>0.7) for farming the Greater amberjack (Seriola dumerili), highlighting unexploited offshore zones in South and North America, Oceania and in the Africa continent. The developed tool can be applied to large-scale studies of different aquaculture species, as well as to other types of marine uses.

An innovative offshore aquaculture cage design and its hydrodynamic behavior for different environmental conditions is presented. The work involves the following blocks: (i) design of the aquaculture cage, (ii) experimental tests performed at IHCantabria facilities (Cantabria Coastal and Ocean Basin, CCOB), (iii) brief description of the ad-hoc time domain numerical model developed, and (iv) calibration of decay tests and sea states cases, in order to be able to simulate different locations of interest for aquaculture stakeholders. The offshore aquaculture cage is a floating cylindrical structure, designed according to different requirements from standards and needs of contacted aquaculture stakeholders. The cage is focused on the growing and farming of fish species in open ocean conditions. It has been specially designed to be able to withstand different environmental conditions, even waves of more than 5m height. Through numerical and physical modeling, it has been shown that it has a good seakeeping and accessibility, to reduce O&M costs. Motions and loads have been registered during the tank testing to calibrate and validate a specific coupled time domain numerical model developed for multi-body structures to simulate the behavior of the assembled structure (cage and sinker connected by tendons), including non-linear damping forces and a FEM approach to model the mooring and the tendon system.

By moving away from coastal waters and hence reducing pressure on nearshore ecosystems, offshore aquaculture can be seen as a possible step towards the large-scale expansion of the marine food production. Integrated multi-trophic aquaculture (IMTA) in nearshore water bodies has received increasing attention and could therefore play a role in the transfer of aquaculture operations to offshore areas. IMTA holds scope for multi-use of offshore areas and can bring environmental benefits from making use of waste products and transforming these into valuable co-products. Furthermore, they may act as alternative marine production systems and provide scope for alternative income options for coastal communities, e.g. by acting as nodes for farm operation and maintenance requirements. This paper summarizes the current state of knowledge on the implications of the exposed nature of the offshore and open ocean sites on the biological, technological and socio-economic performance of IMTA. Of particular interest is improving knowledge about resource flows between integrated species in hydrodynamic challenging conditions that characterise offshore waters.

Offshore aquaculture is increasingly viewed as a mechanism to meet growing protein demand for seafood, while minimizing adverse consequences on the environment and other uses in the oceans. However, despite growing interest in offshore aquaculture, there appears to be no consensus as to what measures commonly define an offshore site or how effects of offshore aquaculture – relative to more nearshore practices – are assessed. This lack of agreement on what constitutes offshore aquaculture has the potential to convolute communication, create uncertainty in regulatory processes, and impede understanding of the ecological implications of offshore farming. To begin addressing these issues, we reviewed and analyzed biologically-focused primary and gray literature (Ntotal = 70) that categorize and quantify characteristics of offshore aquaculture from around the world. We found that many ‘offshore’ descriptions are relatively close to shore (< 3 nm) and significantly shallower (minimum depth ≤ 30 m) than may be assumed. We also uncovered an overall lack of consistent reporting of even the most common location-focused metrics (distance from shore, depth, current), a dearth of impact related studies (n = 17), and narrow scope of the studies themselves (i.e., 82% nutrient pollution). Of the finite subset of articles that investigated negative ecological impacts of offshore aquaculture, we found the probability of any measurable impact from an offshore farm appears to significantly decrease with distance from the farm (probability of measurable response at 90 m ± SE = 0.01 ± 0.03). Such general, but informative points of reference could be more robustly quantified with better systematic and standardized reporting of physical farm characteristics and a broader scope of ecological investigation into the effects of marine aquaculture. With offshore aquaculture still in its infancy, consistent metrics are needed for a comparable framework to guide sustainable offshore aquaculture research and development globally.

Brittle stars (Ophiura spp.) and other benthic macrofauna were collected in a prospective mariculture area in the North Sea to determine if these taxa could be used as indicator species to track nutrients released from future offshore aquaculture sites. We analysed natural carbon and nitrogen stable isotopic signatures in tissues from macrofauna and compared these to six feed ingredients and four experimental diets made thereof, as well as to a commercial feed with and without lipid and carbonate removal. Our data suggest practicability of using isotopic signatures of Ophiura spp. to track aquaculture-derived organic material if plant-based fish diet ingredients and commercial feed were used for fish farming in the German Exclusive Economic Zone. Diets with high fish meal content would not be detected in Ophiura spp. using isotopic measures due to the similarity with the marine background. Our data provide valuable baseline information for studies on the impact of offshore aquaculture on the marine environment.

Aquaculture will be the dominant producer of global seafood in the 21st Century and the emerging open ocean farming sector must play an important role. Current concepts for utilizing the ocean for aquaculture in national Exclusive Economic Zones, include; standalone structures for growing shellfish and finfish and aquaculture production facilities co-located with other, compatible ocean uses, e.g., offshore oil platforms and wind energy towers. There may also be potential for multiple use of marine space incorporating aquaculture at different trophic levels together with artificial reefs, recreational angling and diving and commercial fishing using static gear. This chapter examines the global status of open ocean aquaculture (OOA), stand alone and co-located projects, in national ocean jurisdictions. Regulatory regimes and experiences permitting OOA shellfish and finfish farming in the United States and shellfish farming in the United Kingdom are shared. Examples of the permitting process from several U.S. states are also cited. Finally, conclusions and recommendations are offered to assist nations in formulating and implementing regulatory systems to effectively facilitate commercial aquaculture development in the open ocean environment.

As the worldwide exploitation rate of capture fisheries continues, the development of sustainable aquaculture practices is increasing to meet the seafood needs of the growing world population. The demand for aquatic products was historically satisfied firstly by an effort to expand wild catch and secondly by increasing land-based and near-shore aquaculture. However, stagnation in wild catch as well as environmental and societal challenges of land-based and near-shore aquaculture have greatly promoted efforts to development farming offshore technologies for harsh, high energetic environments. This contribution thus highlights recent technological approaches based on three sample sites which reach out from sheltered near-shore aquaculture sites to sites with harsh wave/current conditions. It compares and evaluates existing technological approaches based on a broad literature review; on this basis, we then strongly advocate for presently available aquaculture technologies to merge with future offshore structures and platforms and to unveil its added value through synergetic multi-use concepts. The first example describes the recent development of longline farming in offshore waters of New Zealand. New Zealand has designated over 10,000 ha of permitted open ocean water space for shellfish farming. The farms range from 8 to 20 km out to sea and a depth of 35-80 m of water. Research has been ongoing for the last 10 years and the first commercial efforts are now developing in the Bay of Plenty. New methods are being developed which should increase efficiency and reduce maintenance with a particular focus on Greenshell mussel (Perna canaliculus) and the Pacific Oyster (Crassostrea gigas), Flat Oyster (Tiostrea chilensis) and various seaweeds. The second case study involves a long-term, open ocean aquaculture (OOA) research project conducted by the University of New Hampshire. During the course of approximately 10 years, the technological aspects of OOA farming were conducted with submersible cages and longlines, surface feeding systems and real time environmental telemetry. The grow-out potential of multiple marine species such as cod (Gadus morhua), haddock (Melanogrammus aeglefinus), halibut (Hippoglossus hippoglossus), blue mussel (Mytilus edulis), sea scallop (Placopecten magellanicus) and steelhead trout (Oncorhynchus mykiss) were investigated at a site 12 km from shore. The last study presents a multi-use aspect of aquaculture for an open ocean site with fish cages attached to existing offshore wind energy foundations. Technological components such as mounting forces and scour tendencies of two different cage structures (cylindrical and spherical) were investigated by means of hydraulic scale modeling. The cages were pre-designed on the basis of linear theory and existing standards and subsequently exposed to some realistic offshore wave conditions. The wind farm "Veja Mate" in German waters with 80 planned 5 MW turbines anchored to the ground by tripiles is taken as the basis for the tested wave conditions. Based on findings stemming from the three example approaches conclusions are drawn and future research demand is reported.

Aquaculture plays an important role in providing food and reducing poverty but it affects environmental change and coastal ecosystems. Remote sensing is a technology that is helpful in the spatial-temporal dynamic monitoring of aquaculture, coastal management, and environmental monitoring. Most research focuses on inland and coastal areas, and little attention is paid to the extensive distribution of marine aquaculture. As an example, we use the freely available Landsat data of the developed marine aquaculture Liaoning Province of China and use the object-oriented automatic extraction method to analyze the spatial and temporal distribution information of marine aquaculture from 2000 to 2018. The accuracy evaluation from the randomly distributed sample points in high-resolution remote sensing images shows that the extraction accuracy for all of the five individual years of aquaculture area was higher than 82%. The results showed that (1) in the past 19 years, the area of marine aquaculture in Liaoning Province showed an increasing trend, which increased from 35.41 km2 in 2000 to 201.83 km2 in 2018, approximately 5.7 times increase in total area, but the growth rate decreased slightly due to government policy and the environmental quality of the sea area. (2) The centroid of offshore aquaculture in Liaoning Province shows a migration pattern to the northeast, in general, extending from the Dalian Bay sea area to the eastern sea area of the Dalian Chengshantou National Nature Reserve of Coastal Landform in the northeastern direction, and the migration distance reached 48.78 km. Moreover, the migration distance between 2005 and 2010 was the largest of all of the periods, reaching 35.43 km. The new marine aquaculture areas are mainly concentrated in the eastern direction of Xiaoyao Bay, the Changshan Islands, and Guanglu Island in Changhai County. (3) The landscape pattern of marine aquaculture in Liaoning Province is split, large-scale aquaculture and small-scale aquaculture are symbiotic, and landscape ecological activities are active. For local managers, this study can provide valuable supporting data for the assessment of marine aquaculture yield in this region, comprehensive control and management of the marine environment, and stability of the marine ecosystem. For other countries or regions, this work provides a great reference value for monitoring the dynamic spatial distribution of marine aquaculture.

Aquaculture activities are inherently undertaken at close proximity to the coastline and near to the shore. Mounting constraints and environmental impact concerns necessitate the development of offshore aquaculture. Challenges include achieving a reliable structural integrity and mooring system design for ultimate state limit, fatigue state limit and accidental and progressive state limit against environmental loading and accidental loading. To avoid mooring system failure, selecting an appropriate breaking strength and limit state for mooring system components is essential. The aim of the present investigation is to describe a mooring system design that accounts for forces and environmental loadings. An evaluation of optimum mooring performance in wave, wind and current loadings on mooring components anchor, buoy and riser elements, that are involved in the dynamics of a mooring system. It is also to generate discussion on the establishment of suitable safety factors and coefficients for the design of very large offshore aquaculture floating structures.

Redox potential is a frequently used measurement in studies under and around marine cage farms to assess the environmental status of marine aquaculture. This study presents an application of a geographic information system (GIS) to document sediment geochemical measures in cobia aquaculture in order to assess the condition of the benthic environment using the Chu-Wan marine fish farm as a case study. The objectives of the study was to combine GIS presentation with chemical measures as an important and innovative methodology in marine aquaculture environmental management. The results show a real distribution patterns for both redox potential and sulfide content in relation to position of the farm and the current pattern.

An alternative technology for removal of nutrients released from mariculture is here suggested. Harvest of cyanobacteria Nodularia spumigena during summer blooms may compensate for release of N and P from mariculture or other sources. Not only content of N in the cyanobacteria but also prevention of N fixation will contribute to nutrient removal from the sea. The harvested product may be used for biogas production, biofuel or agricultural fertilizers.

Traditional agricultural methods and practices have rendered over 100 million hectares of land throughout the world, and over 5.7 million hectares in Australia, unsuitable for most forms of agriculture due to elevated salinity levels. Inland saline aquaculture is an adaptive approach to this environmental problem, and represents a potentially lucrative use for salt-affected land, with many economic, social and environmental benefits possible. Perhaps surprisingly, to date there has been relatively very little research conducted into the suitability (or otherwise) of inland saline aquaculture for the production of various species of microalgae and live feeds, which represent a crucial segment of the aquaculture industry. The key aim of this investigation was to test the hypothesis that all saline waters (natural sea water, artificial sea water and inland ground saline water) would produce uniform growth amongst the live feeds tested. This study expanded on the live feed species being tested to include Artemia (Artemia salina) rotifers (Brachionus plicatilis) and copepods (Cyclop ssp). While there were significant differences in the performance of all the tested live feed species, Nannochloropsis oculataand Brachionus plicatilisshowed better growth rates than those observed for natural seawater. It is hoped that these results can be used proactively by farmers seeking to diversify their crops to include the aquaculture of finfish in salt-affected areas of Australia and elsewhere.

This study aimed to analyze the economic effect of the red sea bream Pagrus major offshore aquaculture production system in Korea. Based on the data collected, revenue and expenses throughout the culture period were calculated, and the net present value and internal rate of return of the ten-year cash flow and cash outflow were estimated in order to determine the economic validity of red sea bream offshore aquaculture production. Results showed that the red sea bream offshore aquaculture production system had high profitability based on the current production and market conditions. This is because of its relatively high survival rate, relatively low feed conversion ratio, and good market price level. However, sensitivity analyses of the main variables indicated that the profitability of red sea bream offshore aquaculture is highly vulnerable to production conditions and market condition changes.

The economic performance of the current inshore rock bream aquaculture industry conducted in Yeosu, Korea was compared with a pilot commercial scale offshore aquaculture farm in Jeju, Korea. Data was collected from 12 inshore farms and two production cycles of the offshore farm for use in Monte Carlo simulations run over a ten year time horizon. Net present value was compared for the inshore farms and two survival rate scenarios for the offshore farm. The offshore farm is expected to have a higher survival rate if it can withstand tsunamis and avoid pollution, disease and red tide impacts that are prevalent inshore. When the offshore farm was modeled with its observed higher survival rate, its average net present value ($1,016,483) significantly outperformed the inshore farms average net present value ($182,153). In the second scenario, the offshore farm survival rate was lowered based on performance data from the inshore farms. Not surprisingly, given the higher investment costs, the offshore farm perfor...

More than 50% of the annual worldwide harvest of mussels is produced in Europe. The mussel cultivation in Germany is based on an extensive on-bottom culture and depends entirely on natural resources for food, spat and space. Due to stakeholder conflicts and a lack of spat availability, mussel farmers tend to move offshore where space is not limited and adequate settlement guaranteed. Newcomers – the offshore wind farmers – are covering large areas in the German Bight which in contrast give the opportunity to use these areas in a multifunctional way by accepting mussel cultivation within the wind farms. This study compiles the basic data for offshore mussel cultivation in close vicinity to a designated offshore wind farm in the open sea of the German Bight and employs different case-scenario calculations to illustrate the impact of changing parameter values on overall profitability or non-profitability of this activity. Primary focus is placed on the production of consumer mussels but seed mussel cultivati...

The increasing global demand for animal protein is a major ecological concern due to its impacts on land use, climate change, global grain supply and fisheries. One method for harvesting animal protein is to grow marine fish. This is widely practiced in coastal environments, but also leads to environmental problems associated with habitat loss and nutrient loading. One alternative is to move marine aquaculture further offshore, away from coastal land-use conflicts and towards ocean currents, which can efficiently dispose wastes. This concept creates a logistical challenge, however, since operators have to transport large amounts of food, fish and fuel to and from offshore cages on a regular basis and in varied weather conditions. In this paper, we discuss the economic feasibility of using offshore oil and gas platforms as bases for open ocean aquaculture in the Gulf of Mexico. We develop net-present value models of a platform-based operation and describe sensitivity analysis of the model output. We conclude that offshore platform-based mariculture may be commercially viable under favorable assumptions, that its viability requires economies of scale and depends principally on the yield per unit of cage volume achieved. The limitations of the analysis are described.

With aquaculture steadily expanding, the need for suitable space has been followed by the development of more efficient, cost-effective, and environmentally sustainable methodologies. Avoiding possible conflicts between the development of commercial aquaculture operations and the environmental impact in coastal areas, utilizing the offshore environment offers the greatest potential for expansion of the industry in most regions throughout the world. Although currents and greater depths generally increase the assimilation capacity and energy of the offshore environment and offer many advantages for aquaculture, a number of challenges associated with developing any activity in the open ocean environment must be taken into consideration. This article summarizes these advantages and challenges, focusing on the first and most crucial step for project development: site selection criteria for open ocean aquaculture. Although most of the concepts and criteria are common to other marine net pen aquaculture operations, we review and present those conditions that are inherent to the open ocean environment and must be considered before developing any offshore aquaculture activity. These encompass basic premises; assumptions; logistics; infrastructure; availability of manpower, services, and materials; legal framework; socioeconomic and political issues; and oceanographic, biological, environmental, and technological criteria. There are no defined set of criteria, as most are interacting and not fixed but interdependent (e.g., depth vs. current velocity). However, suitable sites must meet basic crucial standards summarized here.Site selection is one of the most important decisions for the establishment of a fish farm operation. Satellite images, hydrographic charts, maps, Google Earth, and Geographic Information Systems can all provide important information for preliminary work on site assessment; however, a very careful in situ survey is mandatory to evaluate the suitability of the area.

Fish production is important for the economy in fishing community and for ensuring food security. Climate change will lead a threat to fish productivity. Therefore, a solution offered is to cultivate certain fish, especially those with high economic value by using offshore aquaculture technology. A Sea Station cage is one of the offshore aquaculture cage model that has been used in some locations. As a floating structure, the Sea Station cage need a mooring system to maintain its position. This paper presents the selection analysis of the mooring system designs of the Sea Station cage model that it is suitable with Indonesia Ocean. There are 3 mooring configurations that are linear array, rectangular array, and 4 points mooring type. The nylon mooring rope type has been selected to be used on the 3 mooring configurations and the rope has a diameter of 104 mm with a breaking force of 2.3 MN. Based on results from comparing the 3 mooring configurations, the best mooring configuration is linear array with the tension on the rope of 217 KN and has the safety factor of 0.2 based on DNVGL OS-E301

This study summarizes the activities and findings during a 2 year investigation on the grow-out of blue mussels (Mytilus edulis) and the technical requirements to withstand harsh weather conditions at an offshore location. The experimental sites were two different test areas, each 5 ha in size, 12–15 m in depth, in the vicinity of the offshore lighthouse “Roter Sand” located 15–17 nautical miles northwest of the city of Bremerhaven (Germany). Two versions of submerged longline systems were deployed: a conventional polypropylene longline in 2002 as well as a steel hawser longline in 2003, both featuring different versions of buoyancy modes. The spat collectors and grow-out ropes were suspended perpendicular from the horizontal longline for several months beginning in March of each respective year. The test sites were visited and sampled on a monthly basis using research vessels. Larval abundances in the surrounding water column reached numbers of up to 1,467 individuals m−3. Post-larval settlement success varied through the entire experimental period, ranging from 29 to 796 individuals of spat per meter of collector. Settled mussels reached a shell length of up to 28 mm 6 months after settlement. Based on the growth rates observed for the seed, it is projected that mussels would reach market size (50 mm) in 12–15 months post settlement, and at the observed densities, each meter of collector rope could yield 10.9 kg of harvestable mussels. The polypropylene line resisted storm conditions with wind waves of up to 6.4 m and current velocities of 1.52 m s−1 and was retrieved in autumn of 2002. In contrast, the steel hawser-based line did not withstand the harsh weather conditions. The steel-based line consisted of six twisted strands that were untwisted by the strong currents and turbulences and consequently the individual strands were torn. Additionally, the line was accidentally cut by a yacht in July 2003. The biological study revealed that the tested location near “Roter Sand” has the potential to become an offshore seed production site as well as being exploitable as a grow-out site for mussel production to market size. In light of the technical results, recommendations for mussel culture strategies using a polypropylene longline system are given.

Australia enjoys large inland areas rich in saline waters with potentials to marine aquaculture. In this study, these potentials were examined. Initially 9 different species of marine micro algae from three different divisions, namely Chlorophyta, Bascillariophyta and Chrysophyta, were cultivated using batch culture techniques to examine their growth performance in inland saline ground water (ISGW) with f/2 algae culture media. Dunaliealla tertiolecta was found to have highly significant growth performance while Nitzschia closterium showed significantly negative growth. In general, the average cell densities of all species of Chlorophyta were found to be higher compared to all species of Chrysophyta and Bascillariophyta. Significant differences of lipid were found to be in the Chlorophyta group compare to other two groups. The study successfully demonstrated that the marine microalgal group of Chlorophytes can be successfully grown in ISGW. However microalgae cultivation in ISGW still has enormous potential despite the negative growth of two diatom species and comparatively slow growth of Chrysophytes algae in this study. More controlled research on different groups of microalgae would be a good investment and a synergistic approach is recommended, including water chemistry, hydro-geology, soilwater interactions of and nutritional profiles of microalgae in ISGW.

Aquaculture activities are performed at close proximity to coastline and near shore. Issues and environmental impact concerns and challenges necessitate offshore aquaculture that required reliable structural integrity and mooring system design for ultimate state limit, fatigue state limit and accidental and progressive state limit against environmental loading and accidental loading. To avoid mooring system failure, selecting an appropriate breaking strength and limit state for mooring system components is necessary. Suitable mooring system has been designed by group of researchers at Universiti Malaysia Terengganu. Valuable information was obtained from Technip and Bureau Veritas. The system has been tested in towing tank in Universiti Teknologi Malaysia. This paper describes mooring system design that account for forces and environmental loadings. The paper describes evaluation of optimum mooring performance in wave and current loadings on mooring components anchor buoy and riser elements that are involved in the mooring system dynamics.