Abstract
Abstract Managing interactions between human activities and marine mammals often relies on an understanding of the real‐time distribution or occurrence of animals. Visual surveys typically cannot provide persistent monitoring because of expense and weather limitations, and while passive acoustic recorders can monitor continuously, the data they collect are often not accessible until the recorder is recovered. We have developed a moored passive acoustic monitoring system that provides near real‐time occurrence estimates for humpback, sei, fin and North Atlantic right whales from a single site for a year, and makes those occurrence estimates available via a publicly accessible website, email and text messages, a smartphone/tablet app and the U.S. Coast Guard's maritime domain awareness software. We evaluated this system using a buoy deployed off the coast of Massachusetts during 2015–2016 and redeployed again during 2016–2017. Near real‐time estimates of whale occurrence were compared to simultaneously collected archived audio as well as whale sightings collected near the buoy by aerial surveys. False detection rates for right, humpback and sei whales were 0% and nearly 0% for fin whales, whereas missed detection rates at daily time scales were modest (12%–42%). Missed detections were significantly associated with low calling rates for all species. We observed strong associations between right whale visual sightings and near real‐time acoustic detections over a monitoring range 30–40 km and temporal scales of 24–48 hr, suggesting that silent animals were not especially problematic for estimating occurrence of right whales in the study area. There was no association between acoustic detections and visual sightings of humpback whales. The moored buoy has been used to reduce the risk of ship strikes for right whales in a U.S. Coast Guard gunnery range, and can be applied to other mitigation applications.
Highlights
Marine mammals are an integral part of the ocean ecosystem and many are impacted by human activities, but like most marine organisms, their occurrence, distribution and abundance are a challenge to monitor from unmanned ocean observing systems
We have developed a moored passive acoustic monitoring system that provides near real‐time occurrence estimates for humpback, sei, fin and North Atlantic right whales from a single site for a year, and makes those occurrence estimates available via a publicly accessible website, email and text messages, a smartphone/ tablet app and the U.S Coast Guard's maritime domain awareness software
We developed a system to monitor the occurrence of baleen whales in near real‐time from long‐endurance Slocum ocean gliders (Baumgartner et al, 2013), and have in recent years adapted this system to operate from a purpose‐built moored buoy
Summary
Marine mammals are an integral part of the ocean ecosystem and many are impacted by human activities, but like most marine organisms, their occurrence, distribution and abundance are a challenge to monitor from unmanned ocean observing systems. Visual surveys are limited by weather and sighting conditions, such as fog, rain, heavy seas and darkness For their expense, visual surveys are often inefficient for persistent real‐time monitoring of marine mammal occurrence, albeit for other tasks, such as photo identification, health assessment and abundance estimation, visual surveys remain an essential observing methodology for many species. This paper describes the moored buoy system and analyst protocol, and evaluates the accuracy of near real‐time whale occurrence estimates derived from a buoy located near the Massachusetts coast This evaluation compares occurrence estimates derived in near real‐time to those derived from (a) a review of simultaneously collected archived audio and (b) visual sightings collected by aerial surveys for humpback Megaptera novaeangliae, sei Balaenoptera borealis, fin Balaenoptera physalus and North Atlantic right whales Eubalaena glacialis
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