With the expansion of offshore wind energy in the German Exclusive Economic Zone in the North Sea, numerous fishing grounds will be lost to fisheries in the future. A promising way to compensate for this loss could be strategies of co-use of offshore wind farms. On the one hand, the areas, which are closed to other shipping traffic, could function as protected nursery grounds for important fishery resources, such as cod, lobster or brown crab. On the other hand, so-called spill-over effects could increase the presence of these target species in the immediate vicinity of the parks.
These potentials were investigated by SeaUseTip project leader Vanessa Stelzenmüller together with PhD student Jonas Letschert and other scientists from the Thünen Institute of Sea Fisheries. Their focus was on the brown crab, which can potentially be caught by passive pot fishery in the immediate vicinity of wind farms. Near the island of Helgoland, the researchers deployed a total of 205 baited pots. These were recovered after 24 hours and the brown crabs inside were measured, weighed and their sex determined.
Their results indicate that spill-over effects of 300 to 500 meters to the nearest wind turbine occur, i.e. the animals spread from the wind farms to the immediate surroundings. This, in turn, could provide an opportunity for local beam trawlers to profit from an alternative source of income as part of a passive seasonal pot fishery in the summer. However, this requires, on the one hand, reliable selling opportunities for the catches and, on the other, appropriate legal regulations that allow them to use the crab baskets in the immediate environment of the wind farms.
The scientists have now published their findings in a scientific paper.