Monday, August 4, 2008

PS 13-147: Impact of climate change on ice-associated seals: Breeding site fidelity and philopatry in ringed seals (Phoca hispida)

Micaela E. Ponce1, Brendan P. Kelly2, Stephanie Sell3, David Tallmon1, and Bradley J. Swanson3. (1) University of Alaska Southeast, (2) National Science Foundation, (3) Central Michigan University

Background/Question/Methods

Ringed seals are the primary prey of polar bears and a food source for native people throughout the Arctic. Ringed seals mate, rear pups, molt, and rest on the sea ice surface. Accelerated climate change in the Arctic has begun to greatly influence the character and extent of seasonal sea ice. The impact of climate change on ringed seals will depend greatly on their population structure. From 2001-2003, three ringed seals were unintentionally recaptured at the same breeding location in consecutive breeding seasons,  an inter-annual fidelity to breeding sites suggestive of philopatry. If ringed seals are philopatric, then what was once thought to be a few panmictic ringed seal populations may actually be comprised of many smaller, genetically distinct populations. Small, distinct  populations of ice-associated seals  would be especially vulnerable  to localized extinctions with the loss of seasonal sea ice. During the breeding seasons of 2005-2007, 27 seals were tagged with satellite-linked transmitters designed to track movements between successive breeding seasons. Microsatellite and mitochondrial DNA markers from nearly  400 ringed seals are being analyzed to determine whether interannual fidelity to breeding sites reflects natal philopatry.

Results/Conclusions

To date, 11 of the seals tracked by satellite have been followed between consecutive breeding seasons and all returned to the same sites. Preliminary genetic analyses suggest that ringed seals are not panmictic. The combination of satellite tracking and genetic analysis will bring about  the understanding of  population structure  necessary for the conservation and management of  ringed seals.