The National Oceanic and Atmospheric Administration is stepping up an investigation into the cause of 146 harbor seal deaths along the New England coast since September after influenza A virus was identified in five of the seals.
On Nov. 4, NOAA announced it had declared the seal deaths an "unusual mortality event," which authorizes the federal agency to mobilize additional resources in the investigation.
The declaration followed a consultation with the Working Group on Marine Mammal Unusual Mortality Events, a panel of international experts established under the Marine Mammal Protection Act to monitor and investigate marine mammal health concerns.
Between Sept. 1 and Nov. 3, 146 seal strandings were reported in Maine, New Hampshire, and northern Massachusetts—more than three times the average number of strandings for that time of year. Most of the animals were harbor seals less than a year old.
Samples from five seals analyzed at the New England Aquarium tested positive for influenza A virus. Test results for several other viral pathogens and biotoxins were negative.
Additional evaluations were under way to determine whether the influenza virus has played a role in the deaths.
An investigation team of marine mammal experts will work closely with NOAA, New England Stranding Network partners, and the Working Group on Marine Mammal Unusual Mortality Events to identify and characterize the specific type of influenza A virus found in these animals.
People were being advised not to allow their dogs to approach stranded seals, as seals and dogs can infect each other with diseases, NOAA noted.