Due to the massive boost in construction of wind farms as we race to a greener future. The effects of such a huge development of infrastructure on wildlife within the North Sea has largely overlooked, not least of all harbour porpoises. Since the construction of wind farms in the North Sea populations of harbour porpoises have been declining rapidly.

The UK generates more power from offshore wind farms than any other country, which is of course a huge achievement towards a more sustainable future, however construction of an offshore wind turbine involves the process of piling, which generates high levels of impulsive noise. Unlike countries like Germany, currently, the UK Government has not introduced any legislation on noise limits for offshore construction work. With construction noise pollution reaching up to 250 decibels, this can have detrimental effects on marine life, especially we would argue the harbour porpoise with its profound hearing ability’s that are approximately twenty times that of a human. To put it into perspective if you stood with your head inside the engine of a 747 aircraft, you'd hear a 165-decibel roar. 

Harbour porpoises can suffer temporary or permanent damage to their hearing as a result of impulsive sound, it can even lead to deafness. Harbour porpoises hunt, communicate and travel through the use of echolocation, this ability is greatly affected if their hearing is compromised. Not being able to echolocate could lead to starvation or being separated from their pod. Within the UK damage to your hearing is regarded as an injury and must be viewed as an impairment of an animal’s physical welfare or damage to its health.

There are many sound mitigation strategies that could be utilised to reduce the effects of offshore wind farm construction on harbour porpoises and other marine life. The primary sound mitigation technique includes the reduction of strike energy, and the extension of the contact time between the hydraulic hammer and the pile that is being driven, the ‘prolongation of impact contact time’ as it is termed. There has been proved positive results for marine mammals, but further research is certainly needed to ascertain the extent of the impact. Secondary sound mitigation measures are considerably more significant. The most effective of which are bubble curtains, by laying a perforated hose around the base of the construction sites that then essentially blows bubbles up to the surface creating a sound barrier. During a trial in 2012 while constructing the Borkum West II offshore wind farm, it had great positive effect for marine mammals with the lessening of disturbance of harbour porpoises by up to 90%.

We are campaigning for the use of bubble curtains to be made a legal requirement when constructing offshore wind farms within UK waters. We cannot ignore the fact that the continuous construction of offshore wind farms is having detrimental effects on the harbour porpoises that reside in our waters and as a result are under our protection. The dramatic and positive results in the reduction of sound pollution that trials by other nations have shown cannot be ignored. We have a problem but thanks to new inventions and discoveries we also have a solution. It is our duty as a nation to do all that we can to live in harmony and protect our islands amazing wildlife.