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2013-2015 Bottlenose Dolphin Unusual Mortality Event in the Mid-Atlantic

Bottlenose dolphins have been stranding at elevated rates since July 2013 along the Atlantic coast from New York to Florida (through Brevard County). All ages of bottlenose dolphins are stranding. A few live animals have stranded, but most were found dead, many times very decomposed. Many dolphins have lesions on their skin, mouth, joints, or lungs.

This event has been declared an Unusual Mortality Event (UME).

Based upon preliminary diagnostic testing and discussion with disease experts, we think the mortality event may be caused by cetacean morbillivirus.

Report a stranding (live or dead) to the regional stranding network in the area.


Bottlenose Dolphin Strandings by State
Average: 2007-2012
(July 1 - June 30)
6 15 10 5 64 57 44 18 77 295
(July 1 - July 12)
47 172 84 78 473 349 202 103 319 1827
Note: Data are dolphin strandings that have been confirmed and responded to by Stranding Network Members. Current UME Data are preliminary and may be subject to change as more information becomes available.
* Florida data is through Brevard County.

Why are bottlenose dolphins stranding?

The tentative cause of the UME is cetacean morbillivirus, based upon preliminary diagnostic testing and discussion with disease experts. Here are our results showing the total number of morbillivirus cases identified so far, updated as results become available.

Brucella sp. bacteria have been found in joint, brain or reproductive organ lesions in dolphins in the UME area. Here are our results showing the total number of Brucella cases identified so far. The information will be updated as results become available. We have been investigating Brucella in marine mammal populations across the U.S. since 2011 and are working closely with our stranding network partners, NOAA laboratories, the University of Illinois, CDC, State Departments of Health, National Park Service, and USDA.

The UME investigation is ongoing and additional contributory factors to the UME are under investigation including:

Further evaluations will continue as new animals are found or new evidence determines the direction of the investigation. These rigorous investigations may take several more months to complete. Additional studies are underway to better understand the characteristics of morbillivirus and the potential impacts of this virus on dolphin stocks. These studies are in collaboration with several NOAA laboratories and science centers, stranding network members, non-profit research organizations and academic partners.

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

Map of Stranding Locations 

The following map displays cetacean stranding locations along the Atlantic coast from late June 2013 through April 20, 2015.

Date Range:

Symbols and Colors:
Click to display data associated with that stranding.

The date range slider filters stranding locations to those observed between the dates defined by the position of the two slider drag handles.

Dropdown boxes filter by state, county, and confirmed/suspected morbillivirus.

The Animate button shows spatiotemporal occurrence of the strandings within the currently defined date range that meet the selected filter conditions in the dropdown boxes.

Has this happened before?

In 1987-1988, a bottlenose dolphin morbillivirus mortality event was declared along the mid-Atlantic coast, involving over 740 animals from New Jersey to Florida. That massive die-off, along with a humpback whale mortality event in 1987 off the coast of Massachusetts and the 1989 Exxon Valdez oil spill prompted Congress to formally establish the Marine Mammal Health and Stranding Response Program with the specific instructions for the UME Program as Title IV of the Marine Mammal Protection Act (MMPA).


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Updated: July 29, 2015