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History of Working Group on Marine Mammal Unusual Mortality Events


Unusual Mortality Events

sea lions in rehab
Sea Lions in Rehab
Credit: Pacific Marine Mammal Center

2013 Bottlenose Dolphins in the Mid-Atlantic

2013 Bottlenose Dolphins in Florida

2013 California Sea Lions

2011-2012 Bottlenose Dolphins in Texas

2011 Northern Alaska Pinnipeds

2011 Northeast Pinnipeds

2010-2014 Northern Gulf of Mexico Cetaceans

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Related Links

Criteria for Marine Mammal Unusual Mortality Events

History of the Working Group

Event Fund


Working Group Charter [pdf]

Ross Seal
Ross Seal
(Ommatophoca rossii)
Photo: NOAA

The Working Group on Marine Mammal Unusual Mortality Events ("Working Group" or "WGMMUME") is one component of the Marine Mammal Health and Stranding Response Program.

The Working Group was established in 1991 by NMFS in response to large numbers of marine mammal mortalities in the late 1980s including:

  • humpback whales in the Northeast U.S.
  • bottlenose dolphins on the Atlantic coast
  • Exxon Valdez oil spill in Prince William Sound, Alaska

The Working Group was formalized when Congress passed the 1992 amendments to the Marine Mammal Protection Act (MMPA) as the Marine Mammal Health and Stranding Response Act.

The Working Group's primary role is to determine when an unusual mortality event (UME) is occurring and to help direct the response and investigation.

From 1991 to the present, the Working Group has consulted on 60 marine mammal UMEs throughout the U.S. involving several species of cetaceans (whales, dolphins, and porpoises), pinnipeds (seals and sea lions), manatees, and sea otters.

The Working Group is comprised of members from

  • scientific and academic institutions
  • conservation organizations
  • state and/or Federal agencies

They have a wide variety of expertise in

  • biology
  • toxicology
  • pathology
  • ecology
  • epidemiology

The members are appointed for 3-year terms and meet annually to discuss the past year's UMEs. The Working Group may be consulted throughout the year to review or consult on individual cases, events, or disease issues.

In addition to core members, there are 2 international participants (one from Canada and one from Mexico) and Federal government representatives (currently including NMFS, the U.S. Fish and Wildlife Service, and the Marine Mammal Commission). These members do not have voting privileges, but they contribute significantly to the data reviews, internal discussions, sample analyses, and overall UME investigations.

The Working Group has developed seven criteria that are used to determine if a mortality event is "unusual." The group reviews all possible information, including historical data and current population trends, and determines whether or not an event is truly "unusual" within 24 hours of the initial consultation.

After the working group announces their decision, NMFS or USFWS (depending on which agency has jurisdiction) has 24 hours to officially declare the event unusual and appoint an on-site coordinator.

If it is deemed unusual, the Working Group will provide advice to the appropriate agency (NMFS or USFWS) as to what samples should be collected or how the investigation should be conducted. In addition, the Working Group will provide advice and possibly assist with the entire investigation. When an event is deemed unusual, money from the Marine Mammal Unusual Mortality Event Fund, which is managed by the National Fish and Wildlife Foundation, becomes available to assist with the investigation.

Responses to UMEs are coordinated by either the NMFS or USFWS Regional Offices depending on the species (NMFS has jurisdiction over all cetaceans, seals, and sea lions and USFWS has jurisdiction over walrus, sea otters, manatees, and polar bears) and the regional stranding networks, as well as other Federal, state, and local agencies.

Investigation of such events has led to a greater understanding of the impacts of human-related and natural causes of mortality in marine mammal populations.

For more information on marine mammal unusual mortality events declared by the working group, please refer to the charts and graphs on the UME home page.

Updated: March 27, 2013

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