SJÄLVSTÄNDIGT ARBETE I MARINBIOLOGI 15hp, VT 2020 cd Courtesy of NOAA Concerning the Viability of Offshore Integrated Multi-Trophic Aquaculture (IMTA), and the Possibility for its Optimization. Författare: Leo Näsström Handledare: Michael Tedengren, DEEP Angående möjligheten för utomskärs integrerad multi-trofiskt vattenbruk och dess potentiella optimering. 1 Sammanfattning Ett stagnerat globalt fiske har lett till en snabb utökning av vattenbruket för att tillgodose den globala marknaden. Traditionellt vattenbruk har i västvärlden kännetecknats av monospecifika odlingar, ofta med mycket grav påverkan på sin omnejd. Ett återupptäckt alternativ till denna i längden ohållbara tappning av vattenbruk har därför växt fram. Integrerad multi-trofiskt vattenbruk (IMTA) är en teknik som, genom att odla organismer från flera trofiska nivåer tillsammans, kan minska utsläppen och öka produktiviteten hos en odling. En växande global befolkningen kommer dock leda till ökande konflikter mellan kustnära vattenbruk och intressenter såsom industrier, myndigheter och privatpersoner. Då vattenbruket fortsätter att växa skulle en lösning på dessa konflikter vara att rikta dess expansion mot det öppna havet. Frågan är då om IMTA vore effektivt utomskärs och hur det i så fall skulle kunna optimeras ur både produktions- och kostnadsperspektiv. Denna undersökning tyder på att en pelagial expansion skulle ge en positiv påverkan av de olika ekologiska, ekonomiska och infrastrukturella aspekter rörande utomskärs-IMTA. Dock kräver en sådan förflyttning omfattande förarbete i utvärdering av lämpliga lokaler. En analys av olika arter och dess egenskaper, monetära värde, tillika möjligheter att optimera systemet visar på att utomskärs IMTA är möjligt, men begränsas av ingenjörsmässiga faktorer. Abstract The stagnated global fishing has led to a fast expansion of aquaculture to meet the increasing global demand for seafood. Traditionally aquaculture in the western world has been defined as large monospecific cultures, often with grave implications on its surrounding environment. An alternative to the conventional and unsustainable method has thus been rediscovered and developed. Integrated Multi-Trophic Aquaculture (IMTA) is a technique that, by cultivating organisms of different trophic levels together, can decrease effluents and increase the productivity of a farm. Furthermore, the growing global population will lead to increasing conflicts between coastal aquaculture and other stakeholders such as industries, governments, and private citizens. Since aquaculture continues to grow, a possible solution to such conflicts could be an offshore expansion of aquaculture. However, whether an IMTA system still would be effective in an offshore setting is unclear. This is also the case regarding the possibility to optimize an offshore IMTA system concerning productivity and investment costs. The present article shows that a pelagic expansion of IMTA would positively affect the ecological, economical and infrastructural aspects regarding offshore IMTA compared to inshore IMTA. However, such a transposition would require comprehensive preparatory evaluations of suitable sites. An analysis of several species and their attributes, monetary value, and capability of optimizing the system indicates that offshore IMTA is possible but is limited by structural-engineering factors. 2 Introduction The global demand for seafood and other marine products is on the rise and, due to a stagnated production in capture fisheries, this demand cannot be met by capture fisheries alone. This has led to the rapid development of aquaculture to mitigate the limited supply and meet the increasing demand for seafood and marine products. In 2016, aquaculture supplied about half of the total aquatic produce, excluding aquatic mammals, caimans, crocodiles, alligators, aquatic plants, and seaweed (FAO, 2018). Aquaculture´s production and the corresponding global consumption, both in total and per capita, have been steady; With, as of 2016, China as the major producer of farmed fish. Further followed by, with no internal order: India, Indonesia, Viet Nam, Bangladesh, Egypt, and Norway. By 2016, China and Indonesia were the largest producers of aquatic plants and seaweeds (FAO, 2018). An interesting observation is the absence of producers from the Americas and Europe, the exception being Norway. However, these statistics show the production from all types of aquaculture and do not discriminate between monospecific aquaculture or other techniques of polyculture such as Integrated Multi-Trophic Aquaculture (IMTA). IMTA is a method of cultivating different species from different trophic levels together. The IMTA system is usually composed of a carnivorous finfish species together with extractive species such as macroalgae and bivalves. IMTA thus allows for the reduction of unwanted byproducts from the intensive fed aquaculture, mainly: Particulate Organic Matter, POM: e.g. fecal matter and disregarded food pellets, and dissolved nutrients e.g. ammonium, (e.g. Alexander et al., 2016; Chopin et al., 2004, 2001; Troell et al., 1997). Thereby, IMTA allows a farmer to generate more product/profit per invested dollar, and to significantly reduce the effect of the farm upon the surrounding environment (Chopin et al., 2001), as well as internalizing the environmental costs making the industry more economically sustainable for the society as a whole (Folke et al., 1994). By using IMTA the farmer also diversifies the income of the aquaculture farm viz. providing the farm with uncorrelated sources of income. Thus, allowing a farm to be more resilient against losses of production/income, caused by factors such as a market value drop of a species, disease and unfavorable weather causing a reduced amount of product (Ridler et al., 2007; Troell et al., 2009). Since IMTA is a system built on combinations of different species who have different innate abilities, the efficiency of the whole system depends on what species the combination is constituted by and the ratios therein (Lamprianidou et al., 2015). The whole IMTA system´s bioremediation efficiency can, in addition to the ratios and combinations of species, be optimized by altering the values related to the practices surrounding the system, such as the density of the extractive species grown or its harvesting frequency (Buck and Buchholz, 2004; Lamprianidou et al., 2015). In a study of the European public’s knowledge and preferences of aquaculture and consumerism Alexander (2016) found that out of the 2520 European respondents in five different countries, a majority did not know what integrated aquaculture was. However, when having integrated aquaculture explained to them a majority was positive when asked whether they thought it would have potentially good effects on issues surrounding aquaculture, e.g. food production, sustainability, environmental impact, among others (Alexander et al., 2016). This suggests a positive attitude for integrated aquaculture of the European public that could suggest a great market for environmentally friendly products from IMTA systems. The aquaculture that has been developed and practiced the most in recent history is characterized to be inland pond systems or inshore cages by the coasts (Buck et al., 2018). This has proven to become a factor of conflict among stakeholders competing for space for aquaculture practices, other industries in need of land for expansion, and cultural institutions consequently deteriorating the public perception of aquaculture. These conflicts, the fact that there are unexploited areas offshore, and the potentially reduced environmental impact, have driven the development of offshore aquacultures and a call by the FAO for further expansion of aquaculture into the ocean (Buck et al., 2018; Kapetsky et al., 2013). The EU commission have identified the heavy spatial competition both on the coastlines and offshore but have assessed that with proper preparation and identification of the offshore sites optimal for aquaculture, the spatial competition offshore could be overcome and are thus also advocating for offshore aquaculture development (“EUR-Lex - 52013DC0229 - EN - EUR-Lex,” 2013). Aquaculture thus seems to be bound to expand offshore (e.g. Buck et al., 2018; Buck and Buchholz, 2004; Kapetsky et al., 2013; Potts et al., 2012; Troell et al., 2009) especially in areas that already experience a high population density and conflicts over land-use. Governmental bodies might edict policies to drive the transposition, as the instance of the EU commissions strategy guidelines (“EUR-Lex - 52013DC0229 - EN - EUR-Lex,” 2013). Although, is the IMTA system feasible for offshore aquaculture? How efficient would IMTA be in a high energy environment? And how could it be set up to be energy-optimized? In this present study, these questions will be analyzed by firstly examining the current literature and determine the current status of IMTA and then apply the concepts to an offshore environment. Method In the present study, peer-reviewed literature found through Google Scholar and Web of Science has been analyzed. The main search-words used were ``IMTA Integrated Multi- Trophic Aquaculture´´ alone or with complementary and specifying search-words such as ``Bivalves´´, ``Holothurian´´, ``Algae´´ / ``Macroalgae´´ and ``Echinoids´´. Furthermore, sources found in the references of other review articles on the subject were also used. When concerning data of capture fisheries, aquaculture, and the global markets, the