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Marine Cage Culture and the Environment: Twenty-first Century Science Informing a Sustainable Industry.

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... This controversy about how vulnerable offshore areas really are to fish farming has still not been resolved due to the lack of studies on this issue (Gentry et al., 2017b;Price and Morris, 2015). In general, research claiming to study offshore fish farming (Aguado-Giménez et al., 2011;Froehlich et al., 2017;Lin and Bailey-Brock, 2008;Molina Domínguez et al., 2001;Riera et al., 2015) does not comply with the abovementioned definition of offshore aquaculture (Holmer, 2010). ...
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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.
... Numerous studies have assessed the environmental impacts of mariculture (Ferreira et al., 2008;Karakassis et al., 1998;McGhie et al., 2000;Mitra et al., 2014;Price & Morris, 2013;Wu, 1995) using nutrient budgets that account for inputs and outputs (Neofitou & Klaoudatos, 2008;Thoman et al., 2001;Wild-Allen et al., 2010). These studies, however, have often focused on localized aquaculture sites or cages (Adhikari et al., 2012;Dien et al., 2018;Jiménez-Montealegre et al., 2005;Rosa et al., 2002;Yang et al., 2017), but neglected to examine how aquaculture activities affected the nutrient mass balance of the entire bay ecosystem. ...
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This study examines the spatiotemporal distribution of dissolved and particulate nutrients in Sansha Bay, a coastal bay characterized by complex hydrodynamics (monsoon‐driven river inputs and alongshore coastal waters), and intensive mariculture. However, nutrient stoichiometry and underlying biological responses in this ecosystem remain unclear. High nutrient (39.6–87.5 μmol L⁻¹ dissolved inorganic nitrogen (DIN), 1.79–3.77 μmol L⁻¹ dissolved inorganic phosphorus (DIP)) in winter suggested entrainment of the nutrient‐enriched China Coastal Current superimposed with mariculture inputs; lower nutrient concentrations (9.6–47.1 μmol L⁻¹ DIN, 0.31–1.57 μmol L⁻¹ DIP) in summer, and high Chlorophyll a (0.8–17.0 mg m⁻³) and dissolved oxygen (4.48–8.78 mg L⁻¹), were driven by the exchange of nutrient‐poor coastal waters and enhanced biological consumption. Using the Land‐Ocean Interaction Coastal Zone (LOICZ) mass balance model, field observations of nutrient sources/sinks allowed construction of a robust nutrient budget, in which Δ indicated non‐conservative dissolved nutrient fluxes. In both winter and summer, the external DIN and DIP additions ratio ΔDIN:ΔDIP was ∼21.8–20.4:1, while Si(OH)4 addition/removal occurred seasonally. Potential N biogeochemical processes were also explored. Using a three end‐member mixing model, nutrient biogeochemistry (regeneration/uptake, denoted by δ) within the aquaculture ecosystem was estimated separately from complex physical mixing effects. In winter, nutrient regeneration dominated (δDIN:δDIP ∼20:1; δSi(OH)4:δDIN <1:2), likely due to remineralization of particles (phytoplankton with a 16:1 Redfield ratio and/or fish feed/feces with a non‐Redfield ratio). In contrast, nutrient consumption dominated in summer (δDIN:δDIP ∼13.5:1; δSi(OH)4:δDIN ∼2.4:1). Results of this study are relevant to other coastal bays affected by intensive aquaculture, riverine inputs and coastal waters.
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There is growing interest in cultivating fish, shellfish, and seaweeds in offshore waters. Existing pilot and commercial facilities demonstrate that offshore aquaculture is technically feasible, and that it can improve growing conditions and farmed animal health under some conditions. Many of the advances that have improved the ecological outcomes of nearshore aquaculture are likely to apply to offshore facilities as well. However, some ecological risks will likely persist in the near term. The vulnerability of offshore farm site infrastructure to weather events and vessel collisions could be similar to nearshore sites and result in escape events, and the farming of finfish will likely require feeds that include fishmeal and fish oil, ingredients derived from finite marine resources, and terrestrial-origin ingredients whose embodied carbon footprint may be high. Moreover, because offshore aquaculture occurs in ecological contexts that differ significantly from nearshore contexts, different kinds of ecological risks may also arise as the sector grows. Existing claims on marine space and conflicts with other uses could result in clustering of farms in favorable sites, posing a risk of cumulative impact. The transport, deployment, operation, and decommissioning of infrastructure associated with offshore farms may also pose ecological risks related to harmful interactions with marine wildlife (e.g., entanglement, vessel strikes, and habitat exclusion). Here we synthesize information on the ecological risks posed by offshore aquaculture and how to mitigate them. We also use this synthesis to identify knowledge gaps to inform the development of a research agenda and effective policies that can allow an offshore aquaculture industry to grow in the federal waters of the United States while minimizing environmental impact.
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Mariculture has been one of the fastest-growing global food production sectors over the past three decades. With the congestion of space and deterioration of the environment in coastal regions, offshore aquaculture has gained increasing attention. Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) are two important aquaculture species and contribute to 6.1% of world aquaculture production of finfish. In the present study, we established species distribution models (SDMs) to identify the potential areas for offshore aquaculture of these two cold-water fish species considering the mesoscale spatio-temporal thermal heterogeneity of the Yellow Sea. The values of the area under the curve (AUC) and the true skill statistic (TSS) showed good model performance. The suitability index (SI), which was used in this study to quantitatively assess potential offshore aquaculture sites, was highly dynamic at the surface water layer. However, high SI values occurred throughout the year at deeper water layers. The potential aquaculture areas for S. salar and O. mykiss in the Yellow Sea were estimated as 52,270 ± 3275 (95% confidence interval, CI) and 146,831 ± 15,023 km 2 , respectively. Our results highlighted the use of SDMs in identifying potential aquaculture areas based on environmental variables. Considering the thermal heterogeneity of the environment, this study suggested that offshore aquaculture for Atlantic salmon and rainbow trout was feasible in the Yellow Sea by adopting new technologies (e.g., sinking cages into deep water) to avoid damage from high temperatures in summer.
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Sustainable domestic aquaculture development is a critical component to achieving greater U.S. seafood security in the future, yet detrimental allegations have corrupted public support. A variety of longstanding and inaccurate myths and assumptions directed at offshore aquaculture farming and its regulation have been foisted on the public. This paper refutes the most prevalent critiques by reviewing current policies, regulations, research and industry production practices. These criticisms include: inadequate regulatory oversight; portrayal of farms as being high density factories unconcerned by food waste, untreated discharge, use of antibiotic and antifungal treatments; entanglement of marine mammals; impacts on wild stocks and habitats; use of feed additives to pigment fish flesh; unsustainable use of fish meal in feed formulations; potential market disruption by producing cheap, low quality products; and commercial farms and commercial fishers cannot coexist as for-profit businesses. Marine aquaculture is not risk-free in terms of potential environmental, economic, social, and cultural impacts and challenges remain to achieve a sustainable industry. These challenges are well known and addressable by the U.S. and global research community. Current offshore farming realities bode well for the future: 1) there is a clear global imperative to sustainably produce more seafood to meet growing demand and the U.S. has the marine resources to become a major exporter, if U.S. law can be amended to grant offshore farmers a property right or security of tenure for sites in federal waters; 2) U.S. ocean farmers work within a very complex and effective legal, regulatory, science-driven environment to anticipate and mitigate potential impacts; 3) farm level management decisions and federal and state regulatory frameworks have worked together to bring about environmentally friendly siting, operational, and production outcomes, and 4) the farming community and its advocates in government, universities, and industry recognize it is essential to reach out to decision-makers and the interested public, as well as critics, with the latest research and empirical results to present an accurate picture of risks and rewards to development.
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Mariculture represents approximate 50 percent of global aquaculture production by weight. Fish cages, which consist simply HDPE frame, netting, and mooring system, in fish farming are key elements of sea cage aquaculture. Aquaculture divers are responsible for inspection and maintenance of the underwater structures such as nets, mooring line and anchor, removing dead fish, monitoring the abnormal behavior of fish, assistance harvesting of fish and other periodic underwater works in fish cage farms. In recent years, the demand for aquaculture divers has increased in fish cage farms in both northern and southern Aegean Sea with enhancement of fish production in mariculture. On the other hand, various problems (diving accidents, faulty diving operations, lack of training etc.) related to work conditions and legal regulations of aquaculture divers have emerged. In the study, with the questionnaire consisting of 49 questions, face to face surveys were performed with 162 aquaculture divers in fish farms around Muğla and İzmir provinces between February and May 2019. Results showed the presence that there are three main problems consisting of diving regulations for professional divers, the candidate diving system and diving education which may cause fatal accidents should be improved and revised urgently.
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پدیده تغییر اقلیم و گرمایش زمین، پدیده جهانی است که متاسفانه اکوسیتسم های مختلف را درگیر کرده است و از آنجاییکه جانداران زیستمندان دریایی اکثرا به دمای محیط وابسته هستند، این تغییر ات می تواند در کلیه ابعاد فیزیکی- شیمیایی منبع آبی و شرایط بیولوژیک و فیزیولوژیک و چرخه زیستی موجودات ساکن دریاها نمایان شود. مقاله حاضر به بررسی مروری - تحلیلی این اثرات در آبهای جهانی و همچنین اثرات ایجاد شده بر ذخایر ماهیان آبهای دریایی ایران در محدوده دریای خزر، خلیج فارس، تنگه هرمز و خلیج عمان اشاره دارد. در همین ارتباط راهکار های پیشنهادی به منظور سازش با شرایط ناشی از پیامد های احتمالی تغییر اقلیم در ایران با تاکید بر روند مدیریت شیلاتی تولید و بهره برداری از ابزیان ارائه شده است.که شامل تغییرروش ماهیگیری به بهره برداری از آبهای عمیق و تقویت روشهای ماهیگیری صنعتی را نسبت به ماهیگیری سنتی بهبود بخشید ، زیرا با توجه به شرایط پیش بینی می شود که ذخایر عملا از دسترس آبهای ساحلی خارج می شوند. در برنامه ریزی آبزی پروری نیز گسترش پرورش قفس دریایی در آبهای باز جهت سازش با شرایط تقویت شود.
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Mariculture cage farming in Oman is in its infancy stage. This study provides important baseline information about the initial state of mariculture in Oman and for the sustainable management of future local cage farming. Our main objective was to evaluate the spatio-temporal variations of water quality and hydrography around a gilthead seabream ( Sparus aurata ) cage farm in Quriyat (Sea of Oman). Starting in July 2018, we conducted a monitoring program over one year in which physico-chemical variables and nutrient levels were regularly measured at the farm cages and at reference sites away from the farm. Vertical flow profiles were recorded at the farm and analysed together with remotely sensed data. The results showed no significant differences among physico-chemical variables and nutrient levels between cages and reference sites. However, there were clear seasonal as well as significant short-term variations in the measurements. Winter conditions are usually homogeneous over the water column without reaching extremes. In summer we recorded surface temperatures of up to 32 °C and extended periods of hypoxia below 35 m depth. Periods of pronounced stratification were interrupted by energetic irregular flow pulses that triggered short up or down-welling events which lead to strong variations of temperature and oxygen. We did not measure a significant impact of the cage farm on the local environment. Our results rather point to the particular importance of monitoring temperature and oxygen levels. Both variables can approach threshold levels for fish farming, especially during summer. We determined the relevant characteristics of the local system and defined requirements for adequate monitoring. The findings of this study provide a timely baseline for future research on the interactions between local cage farms and the marine ecosystem and will assist in the planning and management of mariculture in Oman.
Chapter
This book contains 17 chapters. Topics covered are: management of marine aquaculture: the sustainability challenge; marine mammals and aquaculture: conflicts and potential resolutions; recreational fishing and aquaculture: throwing a line into the pond; aquaculture: opportunity of threat to traditional capture fishermen; advances in marine stock enhancement: shifting emphasis to theory and accountability; aquatic polyculture and balanced ecosystem management: new paradigms for seafood production; the role of marine aquaculture facilities as habitats and ecosystems; mangroves and coastal aquaculture; environmental effects associated with marine netpen waste with emphasis on salmon farming in the Pacific Northwest; issues associated with non-indigenous species in marine aquaculture; genetic changes in marine aquaculture species and the potential for impacts on natural populations; what role does genetics play in responsible aquaculture; understanding the interaction of extractive and fed aquaculture using ecosystem modelling; shrimp farm effluents; fish meal: historical uses, production trends and future outlook for sustainable supplies; the use of wild-caught juveniles in coastal aquaculture and its application to coral reef fishes; contending with criticism: sensible responses in an age of advocacy.
Book
Published in Cooperation with THE UNITED STATES AQUACULTURE SOCIETY. The rapid growth of aquaculture worldwide and domestically has caused concerns over social and environmental impacts. Environmental advocacy groups and government regulatory agencies have called for better management to address potentially negative impacts and assure sustainable aquaculture development. Best Management Practices (BMPs) combine sound science, common sense, economics, and site-specific management to mitigate or prevent adverse environmental impacts. Environmental Best Management Practices for Aquaculture will provide technical guidance to improve the environmental performance of aquaculture. This book will be the only comprehensive guide to BMPs for mitigation of environmental impacts of aquaculture in the United States. The book addresses development and implementation of BMPs, BMPs for specific aquaculture production systems, and the economics of implementing best management practices. Written by internationally recognized experts in environmental management and aquaculture from academia, government, and non-governmental organizations, this book will be a valuable reference for innovative producers, policy makers, regulators, research scientists, and students.