What's Going on With Bottlenose Dolphins in the Mid-Atlantic?

NOAA Declares 'Unusual Mortality Event' for Bottlenose Dolphins in the Mid-Atlantic

Danielle Monaghan, a staffer at the Marine Mammal Stranding Center in Brigantine N.J.,  photographs a dead dolphin that washed ashore Wednesday, Aug. 21, 2013, in Spring Lake N.J. This dolphin was the 63rd to die on New Jersey's shores since early July. (AP Photo/Wayne Parry) / AP

The National Oceanic and Atmospheric Administration (NOAA) declared an Unusual Mortality Event for bottlenose dolphins in the Mid-Atlantic region from early July 2013 to the present. An Unusual Mortality Event, as stated by the Marine Mammal Protection Act of 1972, is defined as a “stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.” This declaration will provide scientists with additional research funding in order to find the root cause of the deaths.

NOAA Graph: http://www.nmfs.noaa.gov/pr/health/mmume/midatldolphins2013.html

Since early July, there has been 71 dolphin strandings along the Jersey Coast. Strandings have been reported along the Mid-Atlantic coastline with almost 300 washups from New York to Virginia.  Virginia has reported the highest numbers of strandings at 64.

NOAA Graph: http://www.nmfs.noaa.gov/pr/health/mmume/midatldolphins2013.html

According to NOAA, “all age classes of bottlenose dolphins are involved” and, “Currently, there are no unifying gross necropsy findings although several dolphins have presented with pulmonary lesions.”

Preliminary results indicate that some of the dolphins had pneumonia, while another tested positive for Morbillivirus, a measles-like virus.  However, the underlying cause of the deaths is still under investigation.  Other potential causes that are being researched include “other diseases or pathogens caused by viruses or bacteria; biotoxins caused by harmful algae blooms; pollution or chemicals, especially from concentrated spills; ship strikes; or acoustic trauma from ships or other infrastructure.”

The symptoms of Morbillivirus involves deteriorating body condition along with prominent lesions on the lungs and central nervous tissues. This disease also causes secondary infections, such as pneumonia.  What is most concering about Morbillivirus is that it is an airborne virus. This means the virus is easily spread between dolphins, who generally stay together in pods, through their normal breathing activities. The Morbillivirus has been known to affect species of dolphins in the past 20 years with one notable event occurring along the Mid-Atlantic coast in the 1980s in which 742 dolphins presented with the virus.

Matthew Huelsenbeck, a marine scientist at the nonprofit Oceana, pointed out that “most of the East Coast dolphin deaths have occurred in areas with heavy human footprints, like the Chesapeake Bay.”

The New Jersey Department of Environmental Protection has stated that there is no correlation between the deaths and the water quality which “has been excellent this summer,”suggesting that instead, it is an indication of a “natural disease cycle.” However, dolphins are known to accumulate toxins into their bodies, and NOAA’s marine mammal biologist, Trevor Spradlin, pointed out that “many bottlenose dolphins live on the same coasts and eat the same fish that we do,” so this could mark something greater than a natural disease cycle and is cause for concern.

Perry Habecker, chief of large-animal pathology at the University of Pennsylvania, stated that “’human interaction’- such as aggressive commercial fishing, toxic wastes, and even plastic bags- can contribute to spikes of mortality in marine-mammal populations such as whales, seals and dolphins.” But, for now, the primary cause of the deaths has yet to be identified.  Scientists will know more once they run diagnostic tests on tissue and blood samples.  Click here for updates from NOAA.  

How can you help? 

If you see a stranded dolphin, do not touch it.  Alert local officials and keep pets away from the animal.  Also, in NJ, contact the Marine Mammal Stranding Center at 1-609-266-0538 or click here for other statesin the Mid-Atlantic region.  

This blog post is an updated version of an entry posted by COA on Tuesday, August 13.  Read that post here.