The research did not show indications of additional mortality of harbour porpoises. The report draws the following conclusions: The building of the first offshore wind farm in Dutch waters off the coast near Egmond aan Zee was a complex enterprise and timing of critical phases was aimed at optimizing the probability of good weather (low seastates). A swell of 1 m or more would prevent pile driving and therefore this part of the building process took place in spring/summer. By coincidence, this is also the time of year when porpoise presence is minimal in the general area and this will have contributed to a lower probability of impacting porpoises. Second, a ramp-up procedure and a pinger were always followed, so that any porpoises in the vicinity were given the chance to flee to safe(r) distances before full hammering power was applied. Third, the sheer presence of the pile-driving ship, the very large Svanen, that was working in the area many hours before the actual pile driving to anchor itself at the exact required position was already a ramp-up procedure in itself. No porpoises were seen during three lengthy visits to the site by scientists, during three pile driving events (Leopold & Camphuysen 2007) and there was no indication form numbers and locations of strandings that any additional mortality has been caused by the pile driving for the Off shore Wind farm Egmond aan Zee.