Abstract
Mitigating the effects of human activities on marine mammals often depends on monitoring animal occurrence over long time scales, large spatial scales, and in real time. Passive acoustics, particularly from autonomous vehicles, is a promising approach to meeting this need. We have previously developed the capability to record, detect, classify, and transmit to shore information about the tonal sounds of baleen whales in near real time from long-endurance ocean gliders. We have recently developed a protocol by which a human analyst reviews this information to determine the presence of marine mammals, and the results of this review are automatically posted to a publicly accessible website, sent directly to interested parties via email or text, and made available to stakeholders via a number of public and private digital applications. We evaluated the performance of this system during two 3.75-month Slocum glider deployments in the southwestern Gulf of Maine during the spring seasons of 2015 and 2016. Near real-time detections of humpback, fin, sei, and North Atlantic right whales were compared to detections of these species from simultaneously recorded audio. Data from another 2016 glider deployment in the same area were also used to compare results between three different analysts to determine repeatability of results both among and within analysts. False detection (occurrence) rates on daily time scales were 0% for all species. Daily missed detection rates ranged from 17 to 24%. Agreement between two trained novice analysts and an experienced analyst was greater than 95% for fin, sei, and right whales, while agreement was 83-89% for humpback whales owing to the more subjective process for detecting this species. Our results indicate that the presence of baleen whales can be accurately determined using information about tonal sounds transmitted in near real-time from Slocum gliders. The system is being used operationally to monitor baleen whales in U.S., Canadian, and Chilean waters, and has been particularly useful for monitoring the critically endangered North Atlantic right whale throughout the northwestern Atlantic Ocean.
Highlights
Human activities in the ocean have the potential to impact marine mammals, and if we are to act as responsible stewards of the ocean, we must find a way to mitigate those impacts, in cases where human activities pose an existential threat to one or more species (Laist et al, 2001; Kraus et al, 2005, 2016; Read, 2008; Tyack, 2008)
The Slocum gliders used in this study were able to successfully conduct surveys in a tidally energetic region for nearly 4 months at a time while detecting humpback, sei, fin, and North Atlantic right whales
False detection rates were extremely low for all 4 monitored species on both 15-min and daily time scales
Summary
Human activities in the ocean have the potential to impact marine mammals, and if we are to act as responsible stewards of the ocean, we must find a way to mitigate those impacts, in cases where human activities pose an existential threat to one or more species (Laist et al, 2001; Kraus et al, 2005, 2016; Read, 2008; Tyack, 2008). Banning all human activities in the ocean is untenable, as human society depends on the ocean for transportation and resources (e.g. food), so mitigation efforts must balance the needs of industry and conservation, while acknowledging the strengths and limitations of our ability to monitor both human activities and the abundance or occurrence of marine mammals simultaneously (Verfuss et al, 2018). The latter is a challenge, over long time scales, over large spatial scales, and in real time. Passive acoustic surveys can monitor continuously for sounds produced by nearby marine mammals, often for long periods of time, but species identification can sometimes be difficult, and for most species, only occurrence can be assessed (density estimation is currently possible for a limited number of marine mammals that are obligate vocalizers using very careful study design, but may be possible in the future for facultative vocalizers if our understanding of call rate variability for these species is substantially improved)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
