The Weddell seal is one of the best-studied marine mammals in the world, owing to a multidecadal demographic effort in the southernmost part of its range. Despite their occurrence around the Antarctic coastline, we know little about larger scale patterns in distribution, population size, or structure. We combined high-resolution satellite imagery from 2011, crowd-sourcing, and habitat modeling to report the first global population estimate for the species and environmental factors that influence its distribution. We estimated ~202,000 (95% confidence interval: 85,345 to 523,140) sub-adult and adult female seals, with proximate ocean depth and fast-ice variables as factors explaining spatial prevalence. Distances to penguin colonies were associated with seal presence, but only emperor penguin population size had a strong negative relationship. The small, estimated population size relative to previous estimates and the seals' nexus with trophic competitors indicates that a community ecology approach is required in efforts to monitor the Southern Ocean ecosystem.
|Original language||English (US)|
|State||Published - Sep 2021|
Bibliographical noteFunding Information:
Fig. 1. A map of WESE populations around Antarctica during November 2011. Map of WESE abundance (females only) on fast ice around Antarctica during November 2011 (excluding the northern portion of the western Antarctic Peninsula, where fast ice has disappeared or is decreasing), estimated through a combination of VHR images and crowd-sourcing counts of seals. Numbers of animals across tagging campaigns are referenced in Table 1, including the estimated stable age distribution, based on ground validation from Erebus Bay, Antarctica [e.g., (20)]. The Underlying image is the Reference Elevation Model of Antarctica provided by the Polar Geospatial Center in collaboration with Ohio State University, the National Geospatial Intelligence Agency, and the National Science Foundation.
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