 A CHAIN of tiny ultrasonic devices helped protect schools of playful porpoises during a major £3.5m construction project off the North Wales coast. Experts were drafted in to devise a foolproof method to keep the inquisitive mammals at bay. Welsh Water is trying to protect them while workers laid a kilometre-long marine outfall pipe, blasting through rocky areas, close to the entrance of Holyhead's Breakwater Country Park. And after in-depth consultations with conservationists they homed in on a system of "marine pingers". Welsh Water project manager Simon Cowan said: "We were told by the Countryside Council for Wales that porpoises and seals had been sighted in the area in which we were going to work. "We wanted to protect them and installed the pingers. Once submerged they give off ultrasonic sound which can't be heard by humans but which can be picked up by the porpoises. "It was enough to stop them from getting too close and getting harmed." | 
