Citing a dramatic increase in the number of Atlantic bottlenose dolphins that have died in the past two weeks, the National Oceanic and Atmospheric Administration has declared the deaths to be an “unusual mortality event.”
The agency also is probing whether morbillivirus, the virus responsible for the deaths of about 750 dolphins in 1987 and 1988, is the root cause of death for more than 125 dolphins between New York and Virginia since early July.
The somewhat benign sounding declaration is a rare move by the federal agency charged with monitoring marine mammals nationwide. Only 60 such events have been declared since the program was established in 1991 and only one of those events have included die-offs in New Jersey.
The declaration opens up additional funding to help local stranding centers cover the cost of dealing with the animals. It also establishes an investigatory team that will try to determine the cause of the deaths.
As of Thursday afternoon, the number of dolphins recovered in New Jersey totaled 32, with the most recent animal recovered in Avalon, said Marine Mammal Stranding Center co-director Sheila Dean. The highest number of dolphin strandings has been in Virginia, where more than 100 bottlenose dolphins have been found dead this year, with 49 of those found in July.
Many other dolphins have been reported floating dead in the water, NOAA Fisheries’ National Marine Mammal Stranding Coordinator Teri Rowles said on a conference call with reporters Thursday. “We do recognize that the 125 or so animals that have been reported are an underestimate.”
At least one of seven criteria set by NOAA must be met before the agency will issue the declaration. Among the criteria is a marked increase in the number of strandings compared to the historical record and an increase of strandings in a localized area, according to the guidelines published by NOAA.
Thursday’s declaration opens up additional funding through the National Contingency fund to help local stranding response centers pay for costs associated with necropsies, lab tests and transporting the carcasses or tissue samples. However, Rowles said, “by no means does the contingency fund have enough funding to pay for everything that is going to be involved in this event.”
Dean said how much additional federal funding is available is unclear and stranding centers have to submit budgets.
“The thing is they’ve already told us that money is first-come first-served,” she said. The basic necropsy done at the University of Pennsylvania’s New Bolton Center costs about $75, but Dean said the cost likely will increase because NOAA has requested additional tests.
The investigation into the deaths still is in the early stage, but preliminary results show three dolphins, including at least one in New Jersey, have tested positive for the morbillivirus, which is a virus similar to measles and canine distemper, said Maggie Mooney-Seus, NOAA Fisheries spokeswoman. Scientists are conducting additional tests on the tissue samples and results will be back within the next week, she said.
“Right now, we’re not saying this is a morbillivirus outbreak, but because of the size of it right now, everyone is making that link at this point,” Rowles said. “But that is not a confirmed discovery or cause of this event at this point.”
While morbillivirus is considered the top potential cause, another virus known to cause large scale die-offs in dolphins is influenza, Mooney-Seus said. NOAA scientists are not limiting the investigation to those two illnesses because “viral discovery is high now with wildlife,” she said. If the animal has an impaired immune system from any type of viral infection, the dolphin could die from other secondary infections.
NOAA said in the declaration that there are “no unifying gross necropsy findings,” which means the detailed examinations of the carcasses have not found a physiological link. However, several dolphins have been found with lesions on their lungs, the agency said.
Dolphins are highly social animals and disease can pass easily between them if there is an outbreak. At least four different dolphin populations live within the New York and Virginia range and those animals are expected to begin migrating south sometime in early fall, said Lance Garrison, a research biologist, with NOAA Fisheries.
The unusual mortality event is the 60th to be declared since the agency began issuing such declarations in 1991. Two other die-offs including marine mammals, with large numbers of Atlantic Bottlenose Dolphins, are ongoing in Florida and the northern Gulf of Mexico.
Only one other event has included New Jersey. In 2008, 45 common dolphins died between New Jersey and North Carolina.
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