All development projects create impact to the environment, and since most offshore wind farms are large development projects, they must be approved by the Environmental Impact Assessment before commencing construction. American scientists have recently begun seeking for the optimal construction period in accordance with the possible effects the research wind farms in the East Coast have on marine organisms and the fishery, and have discovered that there is a possibility for offshore wind farms to become maritime rest stops for migratory fish, including salmon and sea bass.
What is currently known is that the aggressive sound waves and noise derived from the piling construction of offshore wind turbines would affect the surrounding marine organisms, and further impact the underwater ecology, migratory fish, and the fishery, thus the construction is mostly adopted with a slow initiation or equipped with sleeves in order to reduce shock impact. In addition, a development also needs to take into account the local ecology so as to evaluate a suitable construction period to avoid construction interference for fish and cetaceans.
The US has placed additional emphases in recent years on the development of offshore wind farms, and believes that the enormous power generated by wind power will be able to support the electricity usage of the East Coast. Hence, University of Maryland began investigating the impact of wind turbine construction on local migratory fish of Atlantic salmon and striped bass, and hoped to understand how a wind farm that is established 27-42km along the coasts of Delaware, Maryland, and Virginia would affect the migratory routes in feeding and nursery for Atlantic salmon and striped bass.
Upon capturing and recording 352 Atlantic salmon and 315 striped bass locally, the team jotted down their sizes, genders, and weight, then implanted acoustic tags inside their bodies, and installed 20 acoustic receivers at the Maryland offshore wind farm. The study pointed out that a deep probing into the migratory habits of fish can confirm that local Atlantic salmon and striped bass do not appear during summertime, which is the optimal period for wind farm construction that produces relatively louder noise.
The research team also found out that offshore wind farms will serve as “rest stops” for these fish in the future, which somewhat resemble the rest stops and service areas along highways, as well as mimic oil drilling platforms and artificial reefs that provide resting and hiding spaces for fish, though the overall impact on Northwest Atlantic fish still requires more information.
Ellie Rothermel, research author at the Center for Environmental Science (University of Maryland), commented, “Through the research the team has further understood the seasonal migratory fish that lay eggs in rivers and forage at estuaries and continental shelves. We were also able to track the locations of fish cluster sightings, and locate the suitable fishing spots, though more detailed and crucial information on coastal migration routes and time has been relatively restricted since this study was only conducted through remote acoustic sensing.”
Looking at past researches, foreign wind turbine foundations that have been in operation for years have exhibited apparent fish agglomeration effect, and the operation noise derived from wind turbines subsequent to the completion of construction has not created major impact to the fish. According to the study of the Molecular Diversity Preservation International (MDPI), the underwater pin piles at the Scandinavian waters have gradually become artificial coral reefs, which attract numerous fish that feed on planktons, and cetaceans will also gather due to the fish cluster, thus forming into another ecosphere.
However, the insufficient study period for the first offshore wind farm in the world that was established in Demark during 1991 has not be able to probe into the prolonged effects of wind power on the ocean, though it is certain that wind farms will indeed create a certain degree of impact on the ocean and birds.
(Cover photo source: Flickr/Archangel12 CC BY 2.0)