I'm interested in any reports stating that mitigation doesn't work, since mitigation of current technology is only now being tried. What is important to remember is that previous significant studies HAVE shown disruptions to harbor porpoise populations during construction (they leave) BUT when construction is finished they come back.

For example, because of harbor porpoises, in Germany there is no construction May - September (as stated) which does add to project costs. This would be the ideal time for construction as wind and waves are generally less, work weather is better, and of course as winter gets closer, conditions get far worse.

Further, it means a period of downtime or less activity for installation ships, although I'm not certain that turbine installation can't be done during this period. ( J? )

To put it into some perspective, drilling operations have significant acoustic effects (not to mention leaking poisons)

What is important to realize is that the offshore wind industry is being very proactive about environmental issues, at great expense, and can not be compared to offshore oil and gas at all. But here's a rig having to use a bubble curtain during drilling:

The net is replete with offshore wind reports to digest.

From Tree Hugger:

Harbor Porpoises May Get Shelter From Offshore Wind Farms

PS. Can't comment further, must focus elsewhere.

"Life shrinks or expands in proportion to one's courage." - Anaïs Nin