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SC/69B/E/06Rev1
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Resource ID
22068
Access
Open
Document Number
SC/69B/E/06Rev1
Full Title
Passive acoustic survey for cetaceans in a potential deep seabed mining region, Clarion Clipperton Zone, Eastern Pacific, summer 2023.
Author
Kirsten F. Thompson, Thomas Webber, Leonidas Karantzas, Severina Miteva, David Santillo, Paul Johnston
Authors Summary
The Clarion Clipperton Zone (CCZ) of the Eastern Pacific is an abyssal area punctuated by numerous seamounts. There is a drive to mine the CCZ for polymetallic nodules, though this is still not a commercial reality. Records suggest that <30 cetacean species are present in the CCZ, though dedicated surveys have yet to be published.
The paper reports results of a passive acoustic survey conducted over 13 days (summer 2023) in two blocks of the CCZ ? NORI-d and TOML-e. The survey covered 4,328km2 of track with 273 hours of recordings. Seventy-four cetacean groups were detected acoustically, with six visual encounters. Sperm whales (Physeter macrocephalus) (one individual), Risso?s dolphins (Grampus griseus) or Pacific white-sided dolphins (Lagenorhynchus obliquidens) based on acoustic characteristics (two groups) and common dolphins (Delphinus delphis) (one group, confirmed by sighting) were detected in addition to 70 dolphin groups that could not be identified to species level. No baleen whales, kogiids or beaked whales were detected. Beaked whales are challenging to detect, such that a lack of detections cannot be taken to confirm absence and could instead be due to a combination of vessel self-noise, survey speeds and beaked whale behaviour.
The findings suggest that more extensive data are needed on distributions and densities to understand the risk of harm to oceanic cetaceans that may arise from deep-sea mining. Also highlighted are opportunities for collaboration across intergovernmental organisations, scientists, non-governmental organisations and regional seas agreements to provide a coordinated response to address future threats from mining. A lack of data on oceanic cetaceans should not mean that emerging industrial use of the deep ocean is overlooked in distant marine realms.
Publisher
IWC
Publication Year
2024
Abstract
The Clarion Clipperton Zone (CCZ) of the Eastern Pacific is a vast oceanic abyssal area punctuated by numerous seamounts. The CCZ is a particular focus for deep seabed companies, though mining is still not a commercial reality. Records from online repositories and field guides suggest that up to 30 cetacean species are present in the CCZ, though dedicated surveys have yet to be published and there is some urgency on better understanding species distributions.
We report the results of a passive acoustic survey for cetaceans conducted over 13 days during summer 2023 in two blocks of the CCZ earmarked for deep seabed mining ? NORI-d and TOML-e. The area surveyed had a mean depth of 4259m, with no charted seamounts. The survey covered 4,328km2 of track and made 273 hours of continuous recordings. Seventy-four (74) cetacean groups were detected acoustically, with six visual encounters. We report the presence of sperm whales (Physeter macrocephalus) (one individual), Risso?s dolphins (Grampus griseus) or Pacific white-sided dolphins (Lagenorhynchus obliquidens) based on acoustic characteristics (two groups) and common dolphins (Delphinus delphis) (one group, confirmed by visual sighting). We also acoustically encountered 70 dolphin groups that could not be identified to species level. No baleen whales, kogiids or beaked whales were detected during this short survey. Beaked whales are challenging to detect, such that a lack of detections cannot be taken to confirm absence of such species during the survey period and could instead be due to a combination of vessel self-noise, survey speeds and beaked whale behaviour.
We confirm at least one threatened species of cetacean present in these blocks of the CCZ ? sperm whales ? and suggest that more extensive data are urgently needed on species distributions, density and habitat use to understand the risk of harm to oceanic cetaceans that may arise from human activities, including deep-sea mining.