Pingers have proved useful in reducing the bycatch of porpoises, and occasionally of dolphins.

But measureing their effect is difficult – it typically needs many days of observers on fishing boats counting dead cetaceans.

Even that is problematic as porpioses often drop out of nets during hauling and are seen, or not seen, dead in the water nearby.

Acoustics provides a much easier first step that may show two things: 1. Is there is a reaction of cetaceans to the pinger? and 2. Does it persist?

Analysis of POD data from pinger studies is quick, but has to take into account an issue you can generally safely ignore: the sounds of the pinger may bias the detection process.

A video on this topic is here