International Marine Conservation Congress – Ice and Seals

Our lab just got word that two abstracts have been accepted for oral presentations at the upcoming International Marine Conservation Congress (IMCC) this May in Victoria, BC. I will be giving a talk that summarizes our work on harp seals and sea ice in the North Atlantic and T.J. Young will be speaking about his work on hooded seals and declining ice conditions in the western and central North Atlantic. The abstracts for these two talks are included below. Congrats to TJ, and thanks to the Rachel Carson Scholars Program for providing financial support for TJ’s trip to the conference.

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Effects of climate variability on sea ice dynamics in hooded seal (Cystophora cristata) breeding regions in the North Atlantic

Tun Jan Young, David W. Johnston, Ari S. Friedlaender and David M. Lavigne

Variability in sea ice cover in the Northern Hemisphere may greatly influence the population dynamics of hooded seals (Cystophora cristata), which rely on seasonal sea ice for breeding in late March. We examined satellite-derived measures of sea ice cover across the North Atlantic during February and March (1979 to 2010) to investigate trends in ice cover at known hooded seal breeding regions. We confirmed a consistent positive correlation between the North Atlantic Oscillation (NAO) index and breeding regions located in the Northwestern Atlantic off eastern Canada. Furthermore, we found a significant inflexion in linear regressions of sea ice cover between 1995 and 1996 in these regions. In contrast, sea ice cover in the West Ice (WI) region in the Northeastern Atlantic was least correlated with NAO phase and regressions of this time series indicate a constant decline in ice concentration of 5 percent per decade. While previous studies indicate that sea ice dynamics in Northeastern Atlantic are controlled, to some extent, by NAO variability, consistently declining sea ice concentrations in the WI region indicate its vulnerability to longer-term climate change. The WI stock of hooded seals has decreased by up to 90% within the last 50 years, and was recently listed as “vulnerable” by the IUCN. Considering the depleted status of this stock and the observed reductions of sea ice in their breeding habitat, stronger conservation efforts are warranted.

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Long-term trends in sea ice cover in the breeding regions of harp seals (Pagophilus groenlandicus)

David W. Johnston, Matthew T. Bowers, Ari S. Friedlaender and David M. Lavigne

We are currently witnessing significant changes in high latitude ecosystems, manifested most noticeably by rapid declines in summer ice extents, significant reductions in perennial ice cover, and declines in sea ice thickness. Rapid changes in temperature and ice conditions at high latitudes pose significant challenges for marine mammals that use sea ice as a platform for breeding and social activity. Harp seals (Pagophilus groenlandicus) use seasonal sea ice in the North Atlantic as a platform on which to give birth and nurse their pups. Recent studies have indicated that sea ice dynamics in harp seal breeding locations are governed largely by the phase and amplitude of the North Atlantic Oscillation (NAO), but have not focused on assessing long-term trends. Here we present the results of a mixed effects linear regression analysis of satellite-derived measures of sea ice cover during February and March 1979 – 2006 in the four major harp seal breeding regions. When accounting for variability in sea ice cover associated with regional NAO effects, the regression model reveals a significant negative trend in sea ice cover across the North Atlantic. The present study indicates that both short and long term climate variability are affecting the breeding regions of ice seals in the North Atlantic. Management strategies for ice-breeding seals should account for local climate effects and larger scale climate trends. [/framed_box]