An apparent population decrease, or change in distribution, of Weddell seals along the Victoria Land coast

David G. Ainley, Michelle A. Larue, Ian Stirling, Sharon Stammerjohn, Donald B. Siniff

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Ground counts during 1959-1968 compared with counts using high resolution (0.6 m2) satellite imagery during 2008-2012 indicated many fewer Weddell seals (Leptonychotes weddellii) at two major molting areas in the western Ross Sea: Edisto Inlet-Moubray Bay, northern Victoria Land, and McMurdo Sound, southern Victoria Land. Breeding seals have largely disappeared from Edisto-Moubray, though the breeding population in McMurdo Sound appears to have recovered from harvest in the 1960s. The timing of decline, or perhaps spreading (lower numbers of seals in more places), is unknown but appears unrelated to changes in sea ice conditions. We analyzed both historic and satellite-derived ice data confirming a large expansion of pack ice mostly offshore of the Ross Sea, and not over the continental shelf (main Weddell seal habitat), and a thinning of fast ice along Victoria Land (conceivably beneficial to seals). Timing of fast ice presence and extent in coves and bays along Victoria Land, remains the same. The reduction in numbers is consistent with an altered food web, the reasons for which are complex. In the context of a recent industrial fishery targeting a seal prey species, a large-scale seal monitoring program is required to increase understanding of seal population changes.

Original languageEnglish (US)
Pages (from-to)1338-1361
Number of pages24
JournalMarine Mammal Science
Volume31
Issue number4
DOIs
StatePublished - Oct 2015

Bibliographical note

Publisher Copyright:
© 2015 Society for Marine Mammalogy.

Keywords

  • Antarctic toothfish
  • Climate change
  • Fast ice
  • Fishery effects
  • Leptonychotes weddellii
  • Population change
  • Ross Sea
  • Sea ice
  • Weddell seal

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