Sunday, August 25, 2013

Studying the Dolphins Off New Jersey

common dolphin Delphinus delphis - NOAA via Wikimedia

Dolphins are dying or being stranded in high numbers this summer along the mid-Atlantic coast, and New Jersey is seeing particularly high rates. Mendy Garron, the Northeast regional stranding coordinator for the National Oceanic and Atmospheric Administration, explains what could be killing the dolphins and what it means for humans.

Under the Marine Mammal Protection Act of 1972, an Unusual Mortality Event (UME) has been declared for bottlenose dolphins in the Mid-Atlantic region from early July 2013 through the present. Elevated strandings of bottlenose dolphins have occurred in New York, New Jersey, Delaware, Maryland and Virginia.

Bottlenose dolphin stranding in NJ. Photo: Marine Mammal Stranding Center via NOAA

Current bottlenose dolphin strandings are over seven times the historical average for the month of July for the Mid-Atlantic Region. All age classes of bottlenose dolphins are involved and strandings range from a few live animals to mostly dead animals with many very decomposed.

According to NOAA, there are "no unifying gross necropsy findings although several dolphins have presented with pulmonary lesions. Preliminary testing of tissues from one dolphin indicates possible morbillivirus infection, although it is too early to say whether or not morbillivirus may be causing this event. Based on the rapid increase in strandings over the last two weeks and the geographic extent of these mortalities, an infectious pathogen is at the top of the list of potential causes for this UME, but all potential causes of these mortalities will be evaluated. Work is underway to determine whether an infectious agent affecting these dolphins is present in collected tissue samples."

Dolphins in New Jersey are not endangered pr threatened. The bottlenose dolphin, tursiops truncatus, are a marine mammal that has the conservation status of "Special Concern."

New Jersey’s coastal waters are home to the coastal form of bottlenose dolphin who prefer marine waters relatively close to shore and over the continental shelf. They will also occasionally enter bays and estuaries in search of prey. Besides the Atlantic Ocean, they have been observed in Delaware and Raritan Bays as well as semi-enclosed water bodies such as Barnegat and Great Bays and the Navesink and Shrewsbury Rivers.

They typically are found in New Jersey waters between spring and fall, but may rarely be observed during winter as well. They are migratory and spend their winters as far south as North Carolina. New Jersey and New York waters represent the northern extent of the range for the coastal form along the US Atlantic coast.

Here's a segment from The Brian Lehrer Show (WNYC) on this issue.

More on NJ dolphins

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