Marine mammals and seabirds will continue to use the waters around operational wave and tidal renewable energy devices, finds a report published by Scottish Natural Heritage (SNH).
A major study of wildlife observations collected over ten years around wave and tidal energy test sites in Orkney has found little evidence of any long-term effects on the use of surrounding seas by the birds and marine mammals living in the area.
The coasts and seas around Orkney are renowned for their wildlife, attracting thousands of visitors to the islands each year. Since 2005, a wide range of wave and tidal energy converters have been tested at two test facilities run by the European Marine Energy Centre (EMEC) in Orkney. Throughout this time, detailed observation records have been kept of the birds and marine mammals present offshore, in and around the test areas.
In 2014, to further improve understanding of how these new technologies influence marine wildlife, SNH, Marine Scotland and EMEC started a detailed analysis of the vast number of observations collected since 2005.
The study investigated how species distribution and density varied across the test sites, relative to different levels of site testing activity, over the ten-year period. Comparisons were made between the animals present before any turbines or their support structures were in place; when support structures only were in place; when turbines were in place; and when turbines were in place and operational.
Statistical analysis of around 10,000 hours of observations at the Fall of Warness tidal test site off Eday indicated a change in density and redistribution of some bird species, including the great northern diver, black and common guillemot, cormorants, shags, ducks and geese, when construction work started. However, in nearly all cases, numbers returned to around previous levels once the tidal turbines were installed and operational. Observations of seals, whales and dolphins revealed similar findings.
Scientists believe that the increased boat activity associated with the initial construction of the devices might cause the temporary disturbance and displacement of some species; but numbers recover once this busy phase of activity is complete and the tidal turbines are operational. For some species observed at the sites, the patterns of change found may in fact be due to population-wide variances that are not directly linked to the activities around the test areas.
At the Billia Croo wave test site, near Stromness, around 6,500 hours of observations were completed, but no significant changes in distribution or density of birds or mammals around the test facilities were detected.
The full report is available on the SNH website: Commissioned Report 947: Analysis of the possible displacement of bird and marine mammal species related to the installation and operation of marine energy conversion systems.