2013–2015 Bottlenose Dolphin Unusual Mortality Event in the Mid-Atlantic (Closed)

Bottlenose dolphin stranding rates were elevated from July 1, 2013 through March 1, 2015 along the Atlantic coast from New York through Brevard County, Florida. This event was declared an Unusual Mortality Event  on August 8, 2013. Over 1,600 bottlenose dolphins stranded during the event, including approximately 69 live dolphins.

All ages of bottlenose dolphins stranded, with more males stranding than females. The majority of carcasses were in moderate to advanced states of decomposition and many dolphins had lesions on their skin, mouth, joints, or lungs. Based on necropsy, histopathology, and diagnostic findings, the mortality event was caused by cetacean morbillivirus.

NOAA has declared the bottlenose dolphin UME in the mid-Atlantic closed.

 

Bottlenose Dolphin Strandings by State

State	Average: 2007–2012 (July 1–March 1)	2013–2015 (July 1–March 1)
New York	6	45
New Jersey	15	153
Delaware	10	74
Maryland	5	76
Virginia	64	416
North Carolina	57	290
South Carolina	44	171
Georgia	18	91
Florida*	77	298
Total	295	1614

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.

Causes of the bottlenose dolphin UME

Based on gross necropsy, histopathology and diagnostic findings, the cause of the UME was cetacean morbillivirus infections, which is in the same family of viruses as measles. Of the dolphins tested for morbillivirus, approximately 92 percent were dolphin morbillivirus-positive (275 of 299). Additionally, a subset of the stranded dolphins had evidence of active Brucella sp. bacterial infections in the joints, brain, or reproductive organs. Of the dolphins tested for Brucella sp. Using PCR testing, approximately 25 percent (39 of 153) were positive for the organism.

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

Previous Atlantic Coast bottlenose dolphin UME

In the years 1987 to 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 specific instructions for the UME Program as Title IV of the Marine Mammal Protection Act.

More Information

• Morbillivirus in Cetaceans Fact Sheet (PDF, 2 pages)
• Brucella in Marine Mammals Fact Sheet (PDF, 2 pages)
• Map of coastal bottlenose dolphin stocks
• Marine Mammal Health and Stranding Response Program
• Marine Mammal Protection
• Media Availability Recordings:
  • August 26, 2013 Media Availability Recording [mp3]
  • August 8, 2013 Media Availability Recording [mp3]
• Unusual Mortality Events