Just like my recent publication in JASA, there is a special issue on JASA focus on passive acoustic monitoring of marine mammals. You can find the content list in the following link:
Passive acoustic monitoring of marine mammals is indeed a still growing field in both ecology and acoustics. Due to the difficulty of marine mammal monitoring, there are more techniques are developed to assist people understand the underwater life. And I believe this is the current trend of ecological monitoring no matter in underwater or terrestrial animals. By using autonomous devices to collect data in long duration or using automatic method to facilitate the analysis on large sample size, more quantitatively results with less subjective determination can be obtained.