Early studies that categorized odontocete pulsed sounds had few means of discriminating signals used for biosonar-based foraging from those used for communication. This capability to identify the function of sounds is important for understanding and interpreting behavior; it is also essential for monitoring and mitigating potential disturbance from human activities. Archival tags were placed on free-ranging Grampus griseus to quantify and discriminate between pulsed sounds used for echolocation-based foraging and those used for communication. Two types of rapid click-series pulsed sounds, buzzes and burst pulses, were identified as produced by the tagged dolphins and classified using a Gaussian mixture model based on their duration, association with jerk (i.e. rapid change of acceleration) and temporal association with click trains. Buzzes followed regular echolocation clicks and coincided with a strong jerk signal from accelerometers on the tag. They consisted of series averaging 359±210 clicks (mean±s.d.) with an increasing repetition rate and relatively low amplitude. Burst pulses consisted of relatively short click series averaging 45±54 clicks with decreasing repetition rate and longer inter-click interval that were less likely to be associated with regular echolocation and the jerk signal. These results suggest that the longer, relatively lower amplitude, jerkassociated buzzes are used in this species to capture prey, mostly during the bottom phase of foraging dives, as seen in other odontocetes. In contrast, the shorter, isolated burst pulses that are generally emitted by the dolphins while at or near the surface are used outside of a direct, known foraging context.
Within the MARCET European project and community framework, a Waveglider®™ SV2 vehicle was deployed, equipped with a passive acoustic monitoring (PAM) device, in a Special Area of Conservation (SAC) of Gran Canaria (Canary Islands, Spain). The soundscape was continuously recorded from 23 July 2018 until 30 July 2018 and was primarily used for marine mammal sound detection. This study aims to compare these automatically embedded detections from the Waveglider®™ with human expert detections. Furthermore, it provides an assessment of the performance of the automatic detector and discusses the use of this type of technology to monitor wildlife, particularly cetaceans. The MARCET project and this study are only possible due to the multidisciplinary integration of veterinary sciences, ecological, zoological, and biological knowledge and mechanical, communication, and electronics engineering. It represents an excellent example of new technologies, capacities, skills, and cutting-edge knowledge where veterinary science education and training should progressively be involved to contribute to the surveillance and control of ocean health.
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