Acoustic Deterrent Device (ADD)

An acoustic deterrent device (ADD), or pinger, is an underwater transmitter that emits short tonal pulses to warn marine mammals away from fishing gear or construction zones, cutting bycatch and injury risk. Pingers on gillnets typically emit 10 kHz pulses near 132 to 145 dB re 1 microPascal at 1 m and have reduced harbor porpoise entanglement by 80 to 90 percent in controlled trials. Higher-power devices, sometimes called acoustic harassment devices, displace seals from aquaculture and pile-driving sites. EU Regulation 812/2004 mandated pingers on certain gillnet fleets. Overuse raises habitat-exclusion and masking concerns, so deployment is weighed against the noise budget.