Bela H. Buck ^1* Kevin Gerald Heasman ² Tyler Sclodnick ³

• ¹ Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), Bremerhaven, Germany
• ² Cawthron Institute, Nelson, New Zealand
• ³ Aquaculture Services, Innovasea, Bedford, Canada

(1) Introduction to the conceptual problem and definition of the term "offshore"; (2) account of the "offshore" definition in national and international laws including UNCLOS (United Nations Convention on the Law of the Sea) (Rozwadowski 2004) and OSPAR (Oslo and Paris Convention for the Protection of the Marine Environment of the North-East Atlantic) (OSPAR Convention 1992); (3) presentation of current aquaculture operations that are offshore and/or exposed; (4) development of indices as assessment tools to describe the exposure of an aquaculture farm; (5) application of these indices in aquaculture with a view to site, species and technology selection, O&M (operation & maintenance); (6) considerations regarding costs of expanding aquaculture from protected to more exposed sites; (7) influence of these definitions under socio-economic aspects; and (8) a conclusion with an outlook of necessary research areas to enable expansion of aquaculture activities into "offshore" and "exposed" water bodies.Four additional publications from non-ICES member scientists are included in this special edition as these scientific contributions fit thematically into the special issue and expand on important topics. Gonzalez et al. (2024) explore opportunities for co-location of aquaculture and clean energy operations. Carroza-Meza et al. (2024) make recommendations on management and regulation of offshore aquaculture to encourage industry growth. Gagnon (2024a and b) reviews the status of off-bottom mariculture of extractive species in exposed environments. Farmers, engineers, scientists of various disciplines, as well as insurers, lawyers, NGO workers and others involved in marine aquaculture often use the term "offshore" when the farm is located in a region where the height of waves and the velocity of currents become a challenge for the technology used, the cultured organism as well as for O&M. But, what exactly does "offshore" mean as opposed to "open ocean" and how do these terms differ from "exposed"? Other site descriptions such as "nearshore" or "inshore" are also used, as well as "coastal" or "EEZ" aquaculture and "farming the deep blue". All of these terms have only a vague description and do not seem to be clearly defined perhaps even well understood.In general understanding, the term "offshore" refers to activities or objects that are located far from the coastline, i.e. something typically located in the open ocean or under harsh oceanic conditions. But how does the specific meaning of "offshore" differentiate itself from the term "open ocean", which is generally understood as a body of water that can, but not necessarily has to be, very far from the coastline and likely requires a certain depth of water and is subject to strong currents and high waves. It becomes even more complicated if this type of site description were also understood to include the construction of aquaculture facilities or structures in the open sea, which are located beyond the continental shelf. This is exactly where the term "EEZ aquaculture" has been used. For if the site is only far enough from the coast and is already outside the territorial sea, i.e. in a zone that is 3 or up to 12 nautical miles from the coast, depending on the country, one could speak of the EEZ. So, these three terms alone vary greatly in the context in which they are used and could be explained collectively as "farming the deep blue". However, this term of "farming the deep blue" has also been established for the required increase in production that could be operated in the open sea, i.e. not necessarily far away and not at all needing to be exposed to the inclement environmental conditions, which we considered in the explanation of the "open ocean aquaculture term". Further, because aquaculture facilities that are close to the coast, traditionally described as "nearshore", can be subjected to strong currents and high waves as well, it can be confused with the above as an "open ocean parameter", and then further confused as it can also be characterized as "exposed". Therefore, "exposed" conditions can exist just in front of the mainland or an island, within inlets and thus be anything but "offshore" or in the "open ocean". Whether this type of aquaculture can then also be described as "inshore" is unclear, because "inshore" is supposedly a part of "nearshore", but closer to the coast than the term "nearshore" actually means. So "nearshore aquaculture" could also be understood as coastal aquaculture, because the terms "inshore" and "nearshore" would be synonyms in this instance. This jumble of terms, further complicated by perspective (Fig. 1), all have no clear definition and are therefore used arbitrarily and must be distinguishable from each other. In particular, the terms "offshore aquaculture" and "exposed aquaculture" need a clear definition as current developments and ongoing search for locations to increase aquaculture production will have to turn to distant and environmentally challenging areas to avoid competition for space with other stakeholders close to the coast.The following publications will investigate and discuss the terms "offshore" and "exposed" with the associated changes in the aquaculture sector and society (see also Table 1). While Buck et al. 2024 (article no. 1) identifies the difficulties in understanding and applying different terms in characterizing a location of an aquaculture farm, Markus (2024) (article no. 2) addresses the term "offshore" and its use and meaning in the context of the Law of the Sea. Heasman et al. 2024a (article No. 3) provide an updated review on exposed and offshore aquaculture worldwide. The exposure index presented in Lojek et al. 2024 (article no. 4) lays out a methodology for classifying sites based on different wave and current parameters (significant wave height, extreme current speed, etc.). Sites can then be characterized using an exposure index. Industry participants will have a much better understanding of what that site is like, how it differs to other sites they are familiar with, and what challenges they encounter. Based on article No. 4, Heasman et al. 2024b (article no. 5) describes the challenges of operating a farm that is spatially far from shore, applying two of the indicative indices to known aquaculture sites. Dewhurst et al. 2024 (article no. 6) uses the example of macroalgae aquaculture to determine additional costs when aquaculture is carried out in exposed or distant marine areas. In article no. 7 (Krause et al. 2024), the challenges to society are analysed, while in a final article (no. 8, Sclodnick et al. 2024) we provide a concluding evaluation followed by an outlook.