Palmer Deep Underwater Acoustic Mooring Deployments 2021-2024

Marine mammals play a crucial role in the ocean ecosystem, yet monitoring their occurrence, distribution, and abundance poses a challenge in remote areas, such as the Antarctic. Traditionally, human observers have conducted visual surveys to detect marine mammals, relying on the animals' need to surface periodically for air. This method is often costly, requiring a large team of observers and the use of ships or aircraft. Additionally, visual surveys are limited by weather and sighting conditions, such as fog, rain, heavy seas, and darkness. Despite their expense, visual surveys are often inefficient for continuous real-time monitoring of marine mammal presence. However, they remain essential for tasks like photo identification, health assessment, and abundance estimation for many species. In recent decades, passive acoustic recorders have become extremely popular for detecting vocally active marine mammals, as they can operate continuously for periods of months to years. This enables a passive method of observation of marine mammals during periods where visual surveys are untenable. We developed a long term mooring system equipped with an underwater acoustic recorder that is capable of recording at 60% for up to 200 days at a time. Since 2022, we have been maintaining these moorings to provide for annual acoustic coverage, and will continue to under the Palmer LTER. This data can be used to compose the underwater soundscape of the region, and a general assessment of year-round acoustic presence of sound producing animals. Further analysis could examine the impacts of inter- and intra- seasonal environmental conditions (e.g., sea ice advance and retreat, sea ice extent, storminess) on the phenology of acoustic presence in the region.