Offshore renewable energy development (ORED) could induce local ecological changes and put species assemblages of conservation interest at risk. If well planned and coordinated, however, ORED could be beneficial to the local subsurface marine environment in several aspects. Acknowledging the scale of ORED, there is increasing interest in the opportunities offered by the resulting changes in fishing patterns, such as exclusion or limi-tation of bottom trawling, in wind and wave farms. Areas encompassing several square kilometres may in some important aspects resemble Marine Protected Areas, and wind and wave-energy foundations and other associated structures can function as artificial reef modules and enhance the local abundance of marine organisms, including commercially important fish and crustaceans. It is also possible that floating offshore energy devices can function as fish aggregation devices for pelagic fish. Here, the potential influence of off-shore wind and wave farms on fish and commercially important crustaceans is described, mentioning the uncertainties with regard to positive and negative effects on benthic and pelagic assemblages and specific species.