Species and habitat surveys are conducted to understand the potential impacts of a floating offshore wind farm on habitats and species and to inform impact analysis and reporting.

What it costs

About £3.1 million for a 450 MW floating offshore wind farm.

Who supplies them

ABPmer, APEM, Fugro, Gardline, HiDef Surveying, Natural Power, Precision Marine and RPS.

Key facts

Species and habitat surveys includes benthic, fish and shellfish, ornithological and marine mammal surveys. Benthic species live on the sea bed and in sediment. The survey data is used to define areas of similar environmental conditions on the sea bed and to inform habitat and species impact studies. More extensive benthic surveys are required for floating offshore wind farms compared to fixed to understand the potential sea bed impacts of the multiple anchoring points required. We expect these surveys to be conducted for all anchor placements initially to produce the most effective broad-scale categorisation of the overall region, as well as attempting to investigate smaller scale features such as reefs. As floating offshore wind technology matures, this may involve sampling of a regular grid. Methods include grab sampling, epibenthic beam trawling and drop-down video (DDV).

Fish and shellfish surveys establish what species are present in the water column within the proposed floating offshore wind farm site and surrounding areas. Beam trawls or otter trawls (dragging a net along the sea bed) are used to sample the species present in the area. Other fishing methods such as lobster pots or gill nets can also be used in areas where trawling cannot take place. Plankton nets can be used for fish egg and arval studies. Surveys are generally undertaken to characterise the species present in the area of the floating offshore wind farm, but also to address specific questions such as whether fish are spawning in the area, should this be an issue for EIA. Surveys can often be done using local fishing vessels, providing they reach minimum safety standards. This approach offers the potential for good engagement with the local fishing community.

Ornithological surveys establish the presence and behaviour of birds within the floating offshore wind farm boundary and surrounding areas. The data from these bird surveys is used to establish the risks to birds that a floating offshore wind farm may pose. Offshore ornithological studies are normally one of the first tasks to be undertaken at a potential floating offshore wind farm site because at least two years of data are needed to establish baseline conditions. This is due to the high level of spatial and temporal variation in bird abundance and distribution throughout the annual cycle. Boat-based and digital aerial surveys are typically used to establish population estimates and to gather behavioural data including species’ flight heights (a key variable used to assess potential collision). Other methods such as GPS tracking, lidar, radar and coastal vantage point surveys can also be used.

Marine mammal surveys establish the diversity, abundance, distribution, and behaviour of cetaceans (including porpoises, dolphins and whales) and seals within the floating offshore wind farm boundary and surrounding areas. Surveys are typically undertaken monthly for at least two years to establish how these variables change across seasons and between years. Marine mammals are surveyed to determine how they make use of the proposed area and therefore the different effects that a floating offshore wind farm may have. These could include potential disturbance and displacement, physical and auditory injury during pile driving, and both direct and indirect habitat loss (for example through effects on prey species). Detailed modelling is conducted to understand the interaction between marine mammals and floating offshore wind components like cables and mooring lines. The methods used depend on the species and site. Traditional visual surveys using boat and aerial platforms are being supplemented or replaced by new, more accurate technologies such as static and towed acoustic monitoring, tagging of individuals with satellite transmitters and remotely controlled video monitoring.

What’s in it

Guide to a Floating Offshore Wind Farm