Science for Environment PolicyFUTURE BRIEF:Sustainable AquacultureMay 2015Issue 11vEnvironment
Science for Environment PolicyThis Future Brief is written and edited by the ScienceCommunication Unit, University of the West of England(UWE), BristolEmail: [email protected] AquacultureContentsIntroductionAquaculture and EU policy1. Pollution and aquaculture341.1 Organic waste and nutrient pollution61.2 Pharmaceuticals and pesticides61.3 Antifoulants81.4 Clean water for aquaculture92. Ecological interactions102.1 Escapees122.2 Diseases122.3 Wild species collection14Concluding remarks15References18Figures and Tables19Reproduced with permission from:Page 5. Figure 1: European Commission (2014c). Availablefrom: ations/pcp en.pdfPage 13. Figure 2: Jensen Ø., Dempster, T., Thorstad, E.,Uglem, I. & Fredheim, A. (2010) Escapes of fishes fromNorwegian sea-cage aquaculture: causes, consequences andprevention. Aquaculture Environment Interactions 1 (1):71–83.Page 17. Tables 1a and 1b: European Commission (2014c).Available from: ations/pcp en.pdf.ImagesReproduced with permission from:Page 3. Fish farm at Bussi, in Abruzzo. iStock.com/seraficusPvage 18. Mussel farm, Primorsko, Bulgaria. (CC BY 2.0)Vasil Raev, Flickr, 2013ISBN 978-92-79-43993-3ISSN 2363-278XDOI 10.2779/6064The contents and views included in Science for EnvironmentPolicy are based on independent research and do not necessarilyreflect the position of the European Commission.To cite this publication:Science for Environment Policy (2015) Sustainable Aquaculture.Future Brief 11. Brief produced for the European CommissionDG Environment by the Science Communication Unit, UWE,Bristol. Available cknowledgementsWe wish to thank Neil Auchterlonie and Keith Jeffery of theCentre for Environment, Fisheries and Aquaculture Science(Cefas), UK, for their input to this report. Further input wasprovided by David Verner-Jeffreys (Cefas), Simon Kershaw(Cefas) and Jonathan David Carl, Orbicon, Denmark. Finalresponsibility for the content and accuracy of the report,however, lies solely with the author.CorrigendumSection 1.2 Pharmaceuticals andpesticides, Anti-parasitics originallydetailed an incorrect reference to astudy on the lethality of anti-parasiticdrug cypermethrin to lobsters, andhas been updated with more recentinformation on pesticide toxicity inNovember 2015.About Science for Environment PolicyScience for Environment Policy is a free newsand information service published by the EuropeanCommission’s Directorate-General Environment,which provides the latest environmental policyrelevant research findings.Future Briefs are a feature of the service,introduced in 2011, which provide expert forecastsof environmental policy issues on the horizon. Inaddition to Future Briefs, Science for EnvironmentPolicy also publishes a weekly News Alert whichis delivered by email to subscribers and providesaccessible summaries of key scientific licyKeep up to dateSubscribe to Science for Environment Policy’sweekly News Alert by emailing:[email protected] sign up online at:http://ec.europa.eu/science-environment-policy
3IntroductionIs sustainable aquaculturepossible?Aquaculture is facing a new era of expansion in Europe. What are the environmental implications of this, and how can thesector expand sustainably? This Future Brief from Science for Environment Policy presents an overview of research intoaquaculture’s impacts, and considers how it could develop in harmony with environmental goals.Fish farm at Bussi, in Abruzzo, Italy. iStock.com/seraficusThe EU’s Blue Growth Strategy1 identifiesaquaculture — the farming of fish, shellfishand aquatic plants — as a sector which couldboost economic growth across Europe andbring social benefits through new jobs. Thereformed Common Fisheries Policy2 also aimsto promote the sector and EU Member Statesare currently developing national aquaculturestrategies.Presently, a quarter of seafood productsconsumed in the EU (including imports) areproduced on farms; in 2011, 1.24 milliontonnes of aquaculture goods were producedin the EU, worth 3.51 billion (EuropeanCommission, 2014a). There are over 14 000aquaculture enterprises in the EU, directlyemploying 85 000 people in total (EuropeanCommission, 2014b). In contrast with otherregions of the world, aquaculture productionis stagnating in the EU, while imports arerising.At the same time, there is a growing gapbetween the amount of seafood consumedin the EU, and the amount caught fromwild fisheries. The European Commissioncalls for this gap to be partly filled withenvironmentally responsible aquaculture(European Commission, 2013). Aquaculturethus has an important role to play in Europe’sfood security as well as its economic growth.1. wth/2. http://ec.europa.eu/fisheries/cfp/index en.htm
4S U S T A I N A B L EA Q U A C U L T U R EIn its expansion, aquaculture must continue to respectenvironmental legislation. This report outlines research intoa selection of water and ecological impacts of aquaculture,alongside information on existing and forthcomingmeasures to mitigate negative impacts. It also highlightsthe possibility that filling certain knowledge gaps couldhelp to further improve aquaculture’s sustainability. Aquaculture operations must respect wildlifeprotection requirements under the Birds and HabitatsDirectives6. In particular, they must comply with theconservation objectives of sites included in Natura20007, the EU network of protected areas, and be subjectto an Appropriate Assessment prior to authorisationin line with Article 6 of the Habitats Directive8.In some cases, aquaculture may have positive effectson nature and water quality, and it has been suggestedthat certain types of farming could help meet the goalsof environmental legislation. The importance for theindustry of water quality in the wider environment is alsoconsidered. The Regulation on the use of alien and locally absentspecies in aquaculture9 addresses the movement ofalien species for aquaculture purposes. Operators mustconduct prior risk assessments and obtain permits totransfer alien aquatic species. The newly adopted EURegulation on the prevention and management ofthe introduction and spread of invasive alien species10will also apply to aquaculture. It will address threatsposed by invasive alien species through actions which:(1.) restrict the introduction and spread of invasive alienspecies; (2.) establish effective early warning and rapidreaction mechanisms; and (3.) manage invasive alienspecies that are already present and widespread in theEU. It will be compatible with the Regulation on theuse of alien and locally absent species in aquaculture.Aquaculture is a hugely diverse industry (see Box 1), and itshould be emphasised that environmental impacts cannotbe generalised across the sector. Impacts vary with species,farming methods and management techniques, preciselocation and local environmental conditions and wildlife.Aquaculture and EU policyAquaculture’s environmental impacts are regulated undera range of EU legal requirements that address broaderissues including water quality, biodiversity protection andsustainable development and planning. Both its impactsand regulations are often interrelated. For instance,water pollution from aquaculture operations may affectbiodiversity.Research presented in this report is relevant to current EUlegal requirements affecting aquaculture. These includethe following. The Marine Strategy Framework Directive (MSFD)3requires EU Member States to achieve 'GoodEnvironmental Status' for their marine waters by 2020,as judged against a range of 11 so-called 'descriptors'4.Thus, national aquaculture strategies must ensure thataquaculture does not have negative impacts in termsof non-indigenous species, eutrophication, seafloorintegrity, concentrations of contaminants (bothin the water generally and in seafood specifically),populations of commercial fish or marine litter. The Water Framework Directive (WFD)5 addressespollution and biodiversity concerns in inland, coastaland transitional waters (e.g. estuaries and fjords).It requires Member States to attain ‘good ecologicalstatus’ and ‘good chemical status’ in these waters.Pollution by ‘priority’ chemical substances, some ofwhich are used in aquaculture, must be progressivelyreduced and, in some cases, phased out completely. Planning and development of new aquaculture sitesfall under the Environmental Impact Assessment(EIA)11 and Strategic Environmental Assessment(SEA)12 directives. These allow environmental concernsto be taken into account very early on in planningprocesses, thus avoiding or minimising negativeimpacts. In addition, the recently-agreed Directive onMaritime Spatial Planning (MSP)13 aims to promotesustainable development and use of marine resources,including for aquaculture, through Maritime SpatialPlans to be established in each Member State by 2021.3. e/index en.htm4. The descriptors are laid out in full in Annex 1 of the MSFD.5. ork/indexen.html6. /habitatsdirective/index en.htm7. index en.htm8. See Commission Guidance on Aquaculture and Natura 2000 00/management/docs/Aqua-N2000%20guide.pdf9. http://europa.eu/legislation summaries/environment/nature andbiodiversity/l28179 en.htm10. en/indexen.htm11. xt.htm12. xt.htm13. e spatial planning/index en.htm
S U S T A I N A B L EA Q U A C U L T U R E5BOX 1.Classifying aquacultureAquaculture is very diverse, but operations can be broadly grouped by the following characteristics:By water typeThis is mainly a distinction between marine and freshwater aquaculture. Marine aquaculture can also takeplace in brackish waters, where sea and freshwaters mix, as well as on land (e.g. in tanks).By species typeSpecies can be classified as ‘finfish’ (such as salmon or carp), shellfish (which includes bivalves, such as mussels, and crustaceans, such as prawns) or plants (such as seaweed or watercress).By intensityIn intensive aquaculture, managers supply the cultured species with all their feed. No feed is provided inextensive aquaculture as feed comes from the natural environment. In a semi-intensive system, managerssupplement natural sources of feed.By water flowIn a closed system, such as a tank or enclosed pond, water is contained and may be tightly controlled andrecirculated. In an open system, such as a sea cage or shellfish raft, water from the natural environment flowsfreely through the farm. In a semi-closed system, some water is exchanged between an enclosed site and thenatural environment.EU aquaculture per product type(percentage of total volume, EU–27, 2011)50%27%Molluscs and crustaceansSeawater fish (including salmon andtrout farmed in seawater)23%Freshwater fish (including trout andeels farmed in freshwater)Figure 1: Source data: eurostat and EUMOFA. Reproduced from European Commission (2014c).
S U S T A I N A B L E61.A Q U A C U L T U R EPollution and aquacultureThis chapter considers how outgoing water quality fromaquaculture farms can be managed (sections 1.1–1.3).It also discusses how environmental legislation can helpensure the clean water that is essential to aquaculture(section 1.4).1.1 Organic waste and nutrient pollutionConcerns have been raised about organic waste andnutrients released by fish farms, especially open farms fromwhich waste and water flows freely. Waste is released assolid particles (e.g. fish faeces and uneaten feed), whiledissolved nutrients (nitrogen and phosphorus) are releasedby fish (through their gills and in their urine), as well as bythe solid waste when it breaks down.These can negatively affect benthic (seafloor) ecosystems inthe local vicinity of the farm, causing ecological impacts. Forexample, Sanz-Lázaro et al. (2011) found that effluent froma Spanish sea bass and sea bream farm disturbed maërl beds(a sensitive red algae habitat protected under the HabitatsDirective). Recently, changes in sediment chemistry andbenthic biodiversity have been recorded beneath a deepwater (190 metres) intensive salmon farm in Norway(Valdemarsen et al., 2012; Bannister et al., 2014).Nutrients released from fish farms have the potentialto cause eutrophication. There is evidence that levels ofnutrients may be elevated up to a distance of about 100metres around a farm, but there is, as yet, limited evidenceof regional impacts. However, Price & Morris (2013)highlight a gap in scientific knowledge of how nutrientsspread over large areas, and of the effects of ever-increasingproduction from multiple farms in a region.One study which does point to regional impacts wasconducted by Sarà et al. (2011). This found thatchlorophyll-a concentrations (an indicator of eutrophicationmonitored under the WFD) were three to ten times higherin the Gulf of Castellammare (size: 370 km2), Italy, than inopen waters. It linked this to sea bream, sea bass and bluefintuna farming in the Gulf, where water currents are unableto disperse pollution easily.& Asmala, 2010; Coalition Clean Baltic, 2014). Langan(2004) recommends that only ‘extractive species’ (whichabsorb nutrients), such as bivalves or seaweed, be farmedin such waters.Such species also have the potential to remove nutrientsemitted by other industries. Shellfish farming itself hasbeen proposed as an ecosystem service tool for loweringnutrients in water from all sources, to help meet the WFD’sobjectives. For example Petersen et al. (2014) estimatedthat harvesting 50–60 tonnes of mussels per hectare ina eutrophic Danish fjord per year would extract 0.6–0.9tonnes of nitrogen and 0.03–0.05 tonnes of phosphorusper hectare.Locating aquaculture operations appropriately is veryimportant and strategic planning can avoid or minimisemost of aquaculture’s environmental impacts. Better sitingis one reason for the drop in the negative impacts of nutrientpollution observed over the past 20 years: computer modelsallow operators to assess a site’s ‘assimilative capacity’ foraquaculture effluent and pick the most suitable locationsfor farming. This can be determined as part of theEnvironmental Assessments needed to obtain a licenceto operate and as required under the EIA Directive orunder the ‘Appropriate Assessment’ required for Natura2000 sites14. ‘Assimilative capacity’ describes the abilityof a specific site to accommodate a fish farm without itspollution causing negative environmental impacts, i.e.pollutants can be sufficiently diluted. It depends on localconditions, including water flow, water depth and thefarm’s size.However, researchers have warned against relying ondilution to deal with nutrient pollution, particularly ifaquaculture is to expand (Pittenger et al., 2007; Troell et al.,2009). Additional changes and measures are thus needed.Managing nutrients and organic wasteSeveral measures are feed-related. Ongoing improvementsto fish feed’s digestibility (so that fish absorb more, andrelease less nutrients) have lowered organic waste, as well asoperating costs (Bureau & Hua, 2010). As with other formsof livestock, fish can be selectively bred to improve their‘feed-conversion ratio’ (i.e. the kilograms of feed needed toproduce one kilogram of product). To illustrate, BrennanConcerns have been voiced about farms in waters which arealready nutrient-rich, such as the Baltic Sea (e.g. by Saikku14. management/guidance en.htm
S U S T A I N A B L EA Q U A C U L T U R E(2002) calculated that lowering the feed-conversion ratioof intensively farmed Australian prawns from 2.5 to 1could cut feed costs by AUS 25 000 (c. 17 000), andreduce nitrogen load by nearly 300 kilograms per hectareof farm, assuming that 10 tonnes of prawns are producedper hectare.Scientists have also called for the use of locally sourcedfishmeal for rainbow trout aquaculture in the Baltic Sea torecycle existing nutrients in the Sea, as opposed to adding7to levels through imported fishmeal (Saikku & Asmala,2010; Gyllenhammar, Håkanson & Lehtinen, 2008).New forms of farming are being considered. For instance,it has been proposed that shellfish and seaweed couldbe farmed alongside — or nearby — finfish to mitigatenutrient pollution from finfish farming. This method, calledintegrated multi-trophic aquaculture, is attracting attentionas a possible future route for sustainable aquaculture. SeeBox 2 for discussion.BOX 2.Integrated multi-trophic aquaculture: ecologically-engineered farmingIntegrated multi-trophic aquaculture (IMTA) involves farming finfish alongside either algae or shellfish.The waste nutrients from the finfish are consumed by the algae and shellfish, thus partly mitigating theenvironmental impacts of finfish culture.IMTA has been practiced for centuries in Asia, but has yet to become established in Europe. Scientificresearch into its impacts is in its early stages, but so far indicates that IMTA could bring financial benefits byboosting algae and shellfish growth.A number of case studies have explored its ability to reduce nutrient pollution. Results vary considerablywith the type of farm and location, but in general suggest that IMTA could help tackle the problem. Detailsof case studies and findings include: A full-scale IMTA farm is currently being piloted in Denmark by the KOMBI project, which is due forcompletion in May 2015 (www.kombiopdraet.dk — in Danish). The farm aims to be ‘zero impact’. Theproject team predict that harvesting 7000-9000 tonnes of mussels will recover 100% of nutrients (88tonnes of nitrogen and 9.6 tonnes of phosphorus) released by 2105 tonnes of rainbow trout each year. Themussels are cultured within the same WFD water body as the trout, but are several miles away. They arefarmed using a space-efficient ‘smartfarm’ system, i.e. on nets, rather than longlines (Carl, 2014a; 2014b). In a Portuguese experiment, 12 tanks (total cultivation area of 18 m2) of the seaweedGracilaria vermiculophylla (used to make agar) removed 0.5% of nitrogen from the effluentof a land-based, recirculating sea bass, turbot and sole farm (Abreu et al., 2011). Theremoval rate could be increased if more seaweed was grown, but more land would beneeded for the seaweed’s tanks (900 m2 for 25% removal and 0.36 ha for 100% removal). Holdt & Edwards (2014) conclude that blue mussels are more effective than kelp in removing nutrients,and need much less space, based on experiences in Denmark and Ireland.The EU IDREEM project is currently developing and testing IMTA systems, and will provide more informationand tools for sustainable marine aquaculture in Europe: www.idreem.eu
S U S T A I N A B L E81.2 Pharmaceuticals and pesticidesAquaculture farms often provide conditions which allowdisease to flourish more easily; for example, animals are oftenstocked at a higher density than wild fish. Most veterinaryproducts and disinfectants to manage animal disease havebeen judged to have minimal negative environmentalimpacts if used correctly (IUCN, 2007). Many sectors ofaquaculture, such as shellfish farming or most extensivepond farming, use no medicines, and pharmaceutical useis closely regulated and inspected in all EU Member States.However, problems, such as risks to non-target species,may occur where pharmaceuticals or disinfectants are usedabove safe limits as defined
Science for Environment Policy Sustainable Aquaculture About Science for Environment Policy Science for Environment Policy is a free news and information service published by the European Commission’s Directorate-General Environment, which provides the latest environmental policy-relevant research findings. Future Briefs are a feature of the .