Acoustic alarms, known as pingers, have been applied to a number of gillnet and driftnet fisheries. Some species avoid nets with pingers, including harbor porpoise (Kraus et al. 1997) and short-beaked common dolphin (Barlow and Cameron 2003), and thus pingers can help reduce bycatch in gillnets.

Scientists are currently testing their effectiveness under different conditions and for specific fisheries. Commercially produced pingers are available, and the development of increasingly specialized and durable versions continues.

However, acoustic alarms may not be equally effective for other species and it is possible that cetaceans become desensitized to the warning sounds over time. Additional concerns remain that the universal application of pingers to gillnets and aquaculture pens could exclude cetaceans from coastal habitat (Carlstrom 2003, Culik et al. 2001, Johnston 2002).

Please read the summary here: Pingers - Info

This info was largely found on cetaceanbycatch.org