The use of active acoustic tags to study the movements and behavior of marine animals (mostly teleosts and elasmobranchs) has increased exponentially in the last two decades with over 40 000 tags deployed worldwide. Tags typically produce narrow band time-coded pulses in the 69 or 180 kHz frequency range. There is a growing concern of the impact of these tags on non-target animals which may be able to hear them. The response of wild bottlenose dolphins (Tursiops truncatus) to the sounds of a pinger tag was investigated. Two CPODS (automated cetacean click loggers) were placed on moorings 2 km apart and a single Vemco V16 69 kHz tag and dummy tag were alternated between moorings over a period of 5 months. Overall dolphin presence (detection positive hours per day) was significantly lower during impact periods, regardless of mooring location while encounter duration was significantly longer. Masking of dolphin detections on the C-POD is unlikely as the duration of the ping is very short (seconds) compared to the unit of measure of presence dolphins (hourly). Results show that the sound alone from acoustic tags may cause significant changes in dolphin distribution or acoustic behavior and further research is recommended.