The Potential Impact of Offshore Wind Farms on Fishes and Invertebrates

The construction and operation of wind farms may have significant effects upon a range of fishes and invertebrates. As wind farms operate for many years, they have the potential for affecting animal stocks adversely over an extended period. Some aquatic animal populations are of national and international importance, including salmon, sea trout, cod and haddock, and crabs and lobsters, all of them being important from a socioeconomic perspective, and they may be adversely affected by wind farms. Some key marine fishes and invertebrates live close to the seabed, and some spawn there, and will be adversely affected by sounds and especially by substrate vibration. Others are in midwater and will also be affected by sounds. Survey and construction activities for wind farms may generate sounds that may affect the behaviour of fishes and invertebrates directly or might mask the detection of important biological signals and orientation cues. Seismic and other surveys, pile driving or drilling, rock breaking, rock filling, dredging and trenching, the installation of foundations, and increased levels of shipping may all produce noise within the frequency bands to which aquatic animals are sensitive. Some noise may also be generated when the wind farm is operational, through the running of the wind turbines and the production of substrate vibrations on the seabed. Electric cables from the wind farm may also affect fishes and invertebrates adversely, by causing habitat damage when they are installed, and by generating noise, chemical pollution, heat, and electromagnetic field emissions during their operation [1]. It is important that migrating fishes reach their destinations without significant delay. Many migratory fishes, including salmon and sea trout, are moving along the coast to particular destinations. There should be no obstruction of their movements which will cause problems in reaching those destinations, whether the fish are wishing to move upstream into rivers flowing into the sea, or have entered the sea from local rivers and are migrating to their feeding grounds. The eel is another fish that may swim past coastal wind farms on their marine spawning migrations. Delays may also result in additional energy costs for returning adult salmon, some of which may have ceased feeding. Spring running adult salmon entering under cold winter conditions may be particularly vulnerable to energy run-down. Migrating fishes may also fail to arrive at their spawning destinations at an appropriate time, incurring adverse effects.