Horns Rev I offshore wind farm is not harmful to fish, a new study reveals. (Photo: DTU Aqua/FIS)

Offshore wind farms benefit local fish life

DENMARK
Thursday, April 12, 2012, 01:20 (GMT + 9)

A new report from the Danish wind-park Horns Rev 1 -- one of the world's largest offshore wind farms -- demonstrates that these farms and fish can coexist in harmony.

The 80 huge turbines at Horns Rev 1 can be found just off Denmark's westernmost point and have been operating for nine years. Like other offshore wind farms, these are located no more than 20 m deep and thus in an area typically swarming with fish.
 
Before the park was built, researchers from DTU Aqua, National Institute of Aquatic Resources in Denmark, did a survey of regional marine life. Biologists then compared the data with data gathered seven years after the wind turbine blades began to turn.

Wind turbine dimensions for turbines placed at Horns Rev. Monopile and a transition piece reach a height of 9 m above the sea surface. (Image: DTU Aqua)

"Our study showed that the turbines have not adversely affected fish life in the area,” said biologist Claus Stenberg from DTU Aqua.
 
Offshore turbines at Horns Rev are placed deep into the seabed and surrounded by a rim of large piles of stones to keep the sea currents from eroding deep trenches in the sand around the turbines. The study suggests that these stone structures act as artificial reefs and provide fish with an abundant supply of food and shelter from the current and attract fish which like a rocky sea bottom. 
 
"Species such as the goldsinny-wrasse, eelpout and lumpfish which like reef environments have established themselves on the new reefs in the area - the closer we came to each turbine foundation, the more species we found," said Stenberg.
 
The researchers were interested in the mills would affect species like the sand eel, one of the most important for the Danish fishing industry.
 
"The study shows that wind farms have not been a threat nor of particular benefit to the sand eel. The sand eel is dependent on the fine sand, in which it buries, to live, and the mills did not affect either the sand grain size on the bottom nor had any impact on the number of sand eels," Stenberg noted.
 
"Horns Rev is situated in an extremely tough environment with strong wave action, which means for example that seaweed forests, together with the small fish that live in them, cannot establish themselves. We would therefore expect the positive reef effects to be even greater still in a park located for example in the more sheltered Kattegat," he continued.

Since the Horns Rev 1 was built, the area has been closed to all fishing activities and the park has become a kind of mini protected area, although too small to have had any significant effects on local fish stocks.

"But presumably several parks located close to one another could have a combined positive effect on spawning and the survival of fish fry, as wind farms which are located downstream of each other can act as a kind of dispersion corridor for eggs and larvae," Stenberg added.

By Natalia Real
editorial@fis.com
www.fis.com

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