Yes, NZ has strict biofouling requirements. There's more to it but generally speaking, the cruise ships need to have the hull cleaned not sooner than 30 days before calling into a NZ port. The rules allow for vessels to have a cleaning booked within 24 hours after arrival but since the only approved treatment option in NZ is haul out/dry docking, and that too only for smaller vessels as large dry docks don’t exist in the country, I would think that this option is out of question for even the smallest cruise ships.