Abstract

Due to an unusually high and significant number (p < 0.05) of harbor seal (Phoca vitulina) strandings and deaths beginning in June 2011, an Unusual Mortality Event (UME) was declared for the northeast coastline from Maine to Massachusetts in November 2011. The peak of the event occurred in September and October, 2011 in which there was a 107% and 189% elevation, respectively, in reported live or dead strandings over the four previous years. Animals were included in the UME cohort if they fulfilled the Case Definition for the UME as established by the investigative team. Confirmed cases were pinniped pups (< 12m) that stranded within the UME region and had gross or histopathologic confirmation of hemorrhagic alveolitis, pneumonia and/or ulcerative dermatitis. Suspect cases were pups with gross or histopathologic confirmation of airway associated bacteria, pulmonary congestion, and/or nasal hemorrhage. Based on preliminary results, 31 (Phoca vitulina: n = 28; Halichoerus grypus: n = 3) cases met the criteria for inclusion either as confirmed (n = 17) or suspect (n = 14) cases. To date, a specific cause for the UME has not been identified. Significant results include identification of influenza A in 20% of samples (n = 35), with Influenza A, subtype H3N8 in five harbor seals and an unidentified subtype of Influenza A in two seals. Additionally, 21 animals of the confirmed or suspect cases tested positive for 1 of 3 different strains of Mycoplasma spp.. Compared with historical data, mortalities in 2012 were not significantly elevated over seal mortalities between 2007 and 2010 and the UME was closed in November 2012. Despite UME closure, testing of samples prospectively collected through the summer of 2012 is ongoing. In addition, histopathology and pathogen screening for Influenza sp. and Mycoplasma sp. on select, archived cases from 2007 through 2010 is also being performed in order to put significant results of the current UME within a broader overall temporal and spatial context.

Acknowledgements

The authors wish to thank and acknowledge the significant contributions of Don Anderson (Woods Hole Oceanographic Institute), Simon Anthony (Columbia University CII), Anne Ballmann (USGS-NWHC), Leslie Burdett Hart (NOAA NCCOS), Julie Cavin (NEAQ), Lynda Doughty (MME), Deborah Fauquier (NOAA MMHSRP), Spencer Fire (NOAA NCCOS), Salvatore Frasca (CVMDL-UConn), Charlie Innis (NEAQ), Hon Ip (USGS-National Wildlife Health Center - NWHC), Keith Matassa (University of New England), Connie Merigo (New England Aquarium-NEAQ), Katie Moore (International Fund for Animal Welfare IFAW), Katie Pugliares (NEAQ), Teri Rowles (NOAA Marine Mammal Health and Stranding Response Program- MMHSRP), Judy St. Leger (Sea World), Jeremiah Saliki (University of Georgia, Animal Veterinary Diagnostic Laboratory AVDL), Susan Sanchez (UGA AVDL), Rosemary Seton (College of the Atlantic), Brian Sharp (IFAW), Inga Sidor (University of New Hampshire), Trevor Spradlin (NOAA MMHSRP), Gordon Waring (NOAA-Northeast Fisheries Science Center), and Stephanie Venn-Watson (National Marine Mammal Foundation).

* Presenting author