Cause of grey seal die-off identified

Photo: Peirre-Yves Daoust

Photo credit: Pierre-Yves Daoust

In March 2012, we reported a mortality event of young grey seals off the coast of Nova Scotia that members of the Canadian Wildlife Health Cooperative (CWHC), Atlantic region, and marine mammal biologists with Fisheries and Oceans Canada investigated.  At the time, this mortality was attributed to severe acute liver damage caused by a protozoan parasite, although the exact identity of this parasite was not determined.  Through close collaboration between members of the CWHC, Atlantic region and British Columbia, and Dr. Michael Grigg and his graduate student, Katie Haman, at the National Institutes of Health, this parasite has now been identified as Sarcocystis, possibly a new species designated Sarcocystis pinnipedi. (See: http://news.sciencemag.org/biology/2014/02/melting-arctic-ice-releases-deadly-seal-parasite)  The life history of this new parasite seems far more complicated than was anticipated and may involve the participation of ringed seals, an Arctic species, as reservoir of this parasite.  The link between ringed seals and grey seals in the emergence of this apparently new disease is still obscure and will undoubtedly be the subject of extensive investigation.

Pierre-Yves Daoust

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