Dwarf sperm whale (Kogia sima) echolocation clicks from Guam (Western North Pacific Ocean)

The cryptic species of the genus Kogia, including the dwarf sperm whale (Kogia sima) and the pygmy sperm whale (Kogia breviceps), are very difficult to observe in any but the most calm sea conditions. However, recordings of signals from wild and captive animals reveal that they echolocate at high frequencies (peak frequencies > 100 kHz) which makes passive acoustic monitoring (PAM) a possibility. We present details from a recent encounter with K. sima in the wild near the island of Guam (Western North Pacific Ocean). Three individuals were observed during a small-boat, visual survey in May 2016, and recordings were collected using a Compact Acoustic Recording Buoy (CARB). These clicks, with mean peak frequency of 126 kHz ( + /- 4.3 kHz), mean click duration of 72 us ( + /- 21 us), and -3 dB bandwidth 5.5 kHz ( + /- 1.6 kHz), had similar properties to recordings of wild K. sima from the Bahamas (Atlantic Ocean), and also appear similar to published recordings from K. breviceps (Madsen et al. 2005). Availab...