Renewable energy is increasing worldwide, including the expansion of offshore wind farms. Important questions arise about how offshore wind development could impact on marine species and environments, and how they would affect fisheries and other marine uses. The Department of Aquatic Resources (SLU Aqua) provides knowledge support on marine renewable energy.
Researchers at the Department of Aquatic Resources (SLU Aqua) participate in research on offshore wind farms and in international expert groups on marine renewables within the International Council for the Exploration of the Sea (ICES).
Researchers from SLU lead the WIND4COCO project, which builds knowledge about the long-term effects of offshore wind farms. The research focuses on the Lillgrund wind farm in Öresund, which started in 2007. Photo: Vattenfall
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In the WIND4COCO project, traditional sample fishing will be combined with data collection with BRUV (baited remote underwater stereo-video systems). SLU has previously used the technology in Byfjorden. A cod swims right next to the bait in front of the cameras, while a shark approaches from behind. Photo: SLU
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The Vindbrukskollen map services provides an overview of current wind farm projects in Sweden.
The WIND4COCO project enhances knowledge about long-term and cumulative effects of offshore wind farms on fish and biodiversity, as well as about the potential for wind farms to coexist with nature conservation and fisheries.
The project combines field surveys, syntheses and dialogues with stakeholders.
WIND4COCO is funded by a research grant from the Swedish Environmental Protection Agency and by Vattenfall, and runs 2024-2027. Vattenfall also contributes time and expertise into facilitating the execution of the project within the Lillgrund wind farm.
The full name of the project is Wind farms in marine ecosystems - towards a sustainable expansion in coexistence with conservation and fisheries.
The field surveys are carried out at the Lillgrund wind farm in the Sound (Öresund), which is the only larger wind farm in Sweden today. In the years around its establishment, in 2007, Lillgrund was associated with an extensive monitoring program to evaluate effects on fish.
WIND4COCO revisits some of these earlier studies to follow-up on how the area’s fish assemblages have developed over the longer term. This provides a unique opportunity to study long-term effects of offshore wind farms, which is currently a significant knowledge gap.
The ongoing vast expansion of off shore renewables enhances the demand for knowledge about potential ecosystem impacts. Gathering experiences from existing wind farms is a key issue. The Lillgrund wind farm is smaller and located shallower those that are now being planned. However, the research provides unique empirical data that in combination with results from other countries contribute to a sustainable design of new offshore wind farms and of their environmental monitoring programs.
The previous studies at Lillgrund showed that certain fish species aggregated close to the turbines, indicating a reef effect. However, the total amount of fish in the wind farm area did not increase or decrease when compared with two reference areas.
These results show the importance of including reference areas for comparison, as well as of studying effects at different distances from the turbines.
WIND4COCO uses the same fish survey methods as in the previous studies, in order to evaluate long term effects. Additionally, baited underwater stereo-video systems are used in order to obtain more comprehensive biodiversity data.
Fishing with fyke nets... (Photo: Mathias Andersson)
... and underwater stereo-video systems . Photo: Johanna Bergman
The WIND4COCO project also investigates whether selective commercial fishing could be possible within offshore wind farms, and if the fishing sector could contribute to data collection in connection to monitoring programs.
Researchers test the use of selective fishing gear in a wind farm setting and evaluate the potential for fishing with fish traps and crayfish pots in offshore wind farms generally.
Fish trap. Photo: Peter Ljungberg
The project invites to three workshops with stakeholders. Two workshops focus on the coexistence of commercial fishing and wind farms (years 2025 and 2026). The third workshop (2026) focuses on environmental monitoring to support follow-up and incremental knowledge development as new wind farms are established.
Several permitting processes for offshore wind farm development are ongoing in Swedish waters. Applications are managed regionally by the Swedish county administrative boards on behalf of the Swedish government.
Managing the applications requires a comprehensive information on the distribution of essential fish habitats in all sea basins around Sweden. This knowledge is needed to identify areas where wind farm development should be avoided, but also to determine conditions for mitigation measures and monitoring in the case of approval.
On commission from the County administrative boards, SLU compiles existing spatial information on the distribution of fish and fish habitats, analyses risks for fish associated with off shore wind farm construction and operation, and identifies key knowledge gaps to be filled in the near future.
Extensive development of offshore wind farms may occupy vast sea areas. This may lead to trade-offs in relation to for example fishing and aquaculture, and risks to nature conservation objectives. To better understand potential consequences of offshore wind expansion, knowledge is needed about the possibilities for wind farms to coexist, or not, with other sea uses.
SLU has synthesized the current state of knowledge about preconditions for offshore wind coexistence with fisheries, aquaculture and conservation, on commission form the Swedish Agency for Marine and Water Management.
The report shows that there is a significant need for knowledge development on coexistence and multi-uses, including pilot testing, technology development, risk analyses, and legislation. The need for adequate and continued communication is strongly emphasized in current literature, as well as the importance of having dedicated strategies to advance possibilities for coexistence. Research and innovation, transparent and structured maritime spatial planning processes, transboundary knowledge exchange, and data access are other key aspects.
Whether offshore wind farms can affect salmon is a current question in the northern Baltic Sea, where several wind farms are planned. Salmon are born in rivers and migrate to the sea, using both the Gulf of Bothnia and the Baltic Proper for foraging. This report synthesises the current state of knowledge about the potential impacts of offshore wind farms on migrating salmon and evaluates risks based on the current state of knowledge. The report has been produced on behalf of the Swedish Agency for Marine and Water Management. It is in Swedish with a summary in English.
The report: Kan havsbaserad vindkraft påverka vandrande lax?
The Vindval research program was dedicated to developing societally relevant knowledge about the effects of wind farms on people, nature, and the environment. The program was a collaboration between the Swedish Energy Agency and the Swedish Environmental Protection Agency, started in 2005 and concluding in 2024. Researchers from SLU have participated in several projects within Vindval.
Koehler[LB1] , B., Bergström, L. (2023). Havsbaserad vindkraft i samexistens med fiske, vattenbruk och naturvård? En inledande kunskapssammanställning. Aqua reports 2023:4. Uppsala: Institutionen för akvatiska resurser. 69 s.
Bergström, L., M. C Öhman, C. Berkström, M. Isæus, L. Kautsky, B. Koehler, A. Nyström Sandman, H. Ohlsson, R. Ottvall, H. Schack & M. Wahlberg (2022) Effekter av havsbaserad vindkraft på marint liv: En syntesrapport om kunskapsläget 2021. Naturvårdsverket Rapport 7049
Naturvårdsverket (2022) Havsbaserad vindkraft – åtgärder för att minska påverkan. Användarblad, pdf.
Bergström, L., T. Malm, N. Åstrand Capetillo, H. Ohlsson, M. Wahlberg, R. Rosenberg, L. Kautsky & D Wilhelmsson (2014) Effects of off shore wind farms on marine wildlife – a generalized risk assessment. Environmental Research Letters 9 034012
Bergström, L., Sundqvist, F., Bergström, U. (2013) Effects of an offshore wind farm on the local demersal fish community. Marine Ecology progress series 485: 199–210. doi: 10.3354/meps10344
Bergström L, Lagenfelt I, Sundqvist F, Andersson I, Andersson M H, Sigray P. (2013). Fiskundersökningar vid Lillgrund vindkraftpark– Slutredovisning av kontrollprogram för fisk och fiske 2002–2010. På uppdrag av Vattenfall Vindkraft AB. Havs och Vattenmyndigheten 2013:18
Lena Bergström, Researcher
Department of Aquatic Resources, Institute of Coastal Research, SLU
lena.bergstrom@slu.se, +46 10 478 41 16
Mattias Sköld, Researcher
Department of Aquatic Resources, Institute of Marine Research, SLU
Ship Management Unit, SLU
mattias.skold@slu.se, +46 (0)10 478 40 46, +46 (0)705-37 87 74
Birgit Koehler, researcher
Department of Aquatic Resources, SLU
birgit.koehler@slu.se, +46(0)10-478 41 60