 The study investigates the physiological and behavioral responses of harbour purposes, fokina-fokina, to a commercial acoustic harassment device, AHD, in Danish waters, revealing that exposure at many kilometres can evoke startle, flight, cardiac responses which may impact blood gas management, breath hold capability, energy balance, stress level and risk of by-catch. The study concludes that current AHDs are too powerful for mitigation use to prevent hearing damage of porpoises from offshore construction. This article was authored by Siri L. Almagard, Jonas Teilmann, Laya Rajanodonate and others.