Increasing human uses of coastal and offshore regions of the North and Baltic Sea cause an increased conflict potential between sectors. For example in German offshore wind turbine sites fishing is excluded. Future losses of space can be mitigated partly with the help of integrated spatial use concepts. Such concepts could encompass co-location of offshore wind turbines and passive gear fisheries or marine aquaculture.
However new regulations and reassignments of spatial uses have not only economic consequence – they entail ecological consequences for the marine ecosystems and ecosystem functions. Such complex cause-effect pathways are still not understood.
The development of comprehensive assessments of costs, benefits and risks of future marine use or spatial management strategies forms the focus of our research. An analysis of the international fishing effort of towed gear within the German EEZ (exclusive economic zone) showed that approximately 15% of the effort of large beam trawls overlap with proposed offshore windfarm sites. Results revealed in addition that when accounting for future fisheries management measures within marine conservation sites in the southern North Sea, Dutch beam trawlers targeting flat fish would be affected the most.
A first study on the feasibility of collocating passive gear fisheries such as gillnets within offshore wind farm sites revealed that the international gillnet fishery could lose up to 50 % in landings within the North Sea German EEZ when wind farm sites areas are closed entirely for fisheries (Stelzenmüller et al. 2016). The study recommends further to conduct comprehensive and area specific scoping studies as a baseline to actually decide on the implementation of a sustainable co-location of sectors. Another study shows that at least 30 % of the proposed wind farm sites could be suitable for offshore aquaculture, thus indicating a synergy potential between sectors.
Our results suggest that the assessments of spatial management strategies require comprehensive, holistic (environmental and economic) as well as small scale (“bottom-up”) analyses.