Estimating minke whale (Balaenoptera acutorostrata) boing sound density using passive acoustic sensors

• Main Authors: Martin, Stephen W., Marques, Tiago A., Thomas, Len, Morrissey, Ronald P., DiMarzio, Nancy, Moretti, David, Mellinger, David K., Jarvis, Susan
• Other Authors: Hatfield Marine Science Center
• Format: Article in Journal/Newspaper
• Language: English; unknown
• Published: Society for Marine Mammalogy
• Subjects: Balaenoptera acutorostrata; minke whale
• Online Access: https://ir.library.oregonstate.edu/concern/articles/cv43nx40r

Density estimation for marine mammal species is performed primarily using visual distance sampling or capture-recapture. Minke whales in Hawaiian waters are very difficult to sight; however, they produce a distinctive “boing” call, making them ideal candidates for passive acoustic density estimation. We used an array of 14 bottom-mounted hydrophones, distributed over a 60 × 30 km area off Kauai, Hawaii, to estimate density during 12 d of recordings in early 2006.We converted the number of acoustic cues (i.e., boings) detected using signal processing software into a cue density by accounting for the false positive rate and probability of detection. The former was estimated by manual validation, the latter by applying spatially explicit capture-recapture (SECR) methods to a subset of data where we had determined which hydrophones detected each call. Estimated boing density was 130 boings per hour per 10,000 km² (95% CI 104–163). Little is known about the population’s acoustic behavior, so conversion from boing to animal density is difficult. As a demonstration of the method, we used a tentative boing rate of 6.04 boings per hour, from a single animal tracked in 2009, to give an estimate of 21.5 boing-calling minke whales per 10,000 km². Keywords: Cue count, Boing vocalization, Spatially explicit capture-recapture, Passive acoustic density estimation, Passive acoustic monitoring