Marine Mammal Commission

Marine Mammal Health and Strandings

Connections between Marine Mammal Health, Ocean Health, and Human Health

Report a Stranded/Beached Marine Mammal

For more information about reporting a stranded, beached, or injured marine mammal, visit NOAA’s stranding page for hotline information.

Marine mammals can be used as indicators of the health of marine ecosystems because they are long-lived, can be long-term coastal residents, feed high up in the food web (like humans, and eat many of the same types of fish as humans), have tissues and organs that may accumulate toxins (like humans), and often swim in the same waters as humans.

Increases in reports of diseases in marine mammals have raised concerns that ocean health is deteriorating (Gulland and Hall, 2007). As marine mammals and humans share a similar physiology, as well as diet and habitats in some regions, this deterioration also may impact human health. Marine mammals may be exposed to environmental stressors such as chemical pollutants, harmful algal blooms (HABs), pathogens, and man-made and natural disasters.

Line graph showing the increase in the number of papers on diseases in marine mammals from the 1960s to 2006.

Line graph showing the increase in the number of papers on diseases in marine mammals from the 1960s to 2006. (Gulland and Hall, 2007)

What happens to marine mammals as a result of exposure to these stressors (often in combination) can have implications for humans in terms of their health and access to marine resources.

Understanding Marine Mammal Health

Marine mammals are adapted for a life in the ocean, but may strand on shore due to environmental conditions, disease or following death at sea. Investigations of these stranding events increase our understanding of the health of marine mammals and, by their connection to it, the health of the ocean. Understanding these factors is crucial to meeting the Marine Mammal Commission’s primary goal to maintain marine mammals as functioning elements of healthy ecosystems.

The National Oceanic and Atmospheric Administration (NOAA) Marine Mammal Health and Stranding Response Program (MMHSRP) was established under Title IV of the Marine Mammal Protection Act (MMPA) and is responsible for coordinating national response to stranded pinnipeds (seals) and cetaceans (whales). The MMHSRP does this through collaborations with federal and state facilities as well as via a volunteer network of regional stranding responders, involving aquaria, academic institutions, and non-governmental organizations (NGOs).

Image of scientist measuring a whale tail.

Marine Mammal Commissioner and veterinarian, Dr. Frances Gulland, responds to a stranded whale. (The Marine Mammal Center)

The activities and capacities of stranding network member institutions may be supplemented or enhanced through an annual program of competitive federal Prescott grants. The U.S. Fish and Wildlife Service (FWS) coordinates responses to stranded manatees, sea otters, polar bears, and walruses.

The Global Stranding Network (GSN) supports international marine mammal stranding response. The GSN assists with strandings of all marine mammal species and works closely with the International Whaling Commission’s Strandings Initiative to share best practices, provide relevant trainings, and increase collaboration and capacity to respond to marine mammal strandings worldwide.

Unusual Mortality Events (UMEs)

When more than two marine mammals strand at the same time in the same general area it is known as a mass stranding. Mass strandings occur quite frequently in the United States and in Cape Cod, Massachusetts in particular. These strandings involve anywhere from a few, to several hundred animals. Unusual Mortality Events (UMEs) are specifically defined under Title IV of the MMPA as strandings that are “unexpected, involve a significant die-off of any marine mammal population, and demand immediate response,” including scientific investigation.

UMEs between 1991 and 2021, showing the number of declared events and known causes per year. (NOAA)

Since the UME program was established in 1991, there have been more than 60 formally declared UMEs across all coasts of the United States. The most commonly affected species are bottlenose dolphins, California sea lions, and Florida manatees and the most common UME causes include infections, human interactions, and biotoxins (poisonous substances produced by living organisms, usually Harmful Algal Blooms, HABs). For more information on UMEs, visit NOAA’s UME Web page.

Marine Mammal Health Monitoring and Analysis Platform (Marine Mammal Health MAP)

Because the Commission recognizes the importance of understanding the health of marine mammals as part of healthy ecosystems, we are committed to focusing the next five years on developing the Marine Mammal Health MAP.

Image of California sea lions in pool.

Stranded juvenile California sea lions recuperating at The Marine Mammal Center in Sausalito. (The Marine Mammal Center)

This project’s mission is to bring together measures of ocean and marine mammal health using a Web-based data management platform—the Marine Mammal Health Monitoring and Analysis Platform (Marine Mammal Health MAP). The MAP will provide online access to marine mammal health data collected through stranding events, and health assessments (among others) that can be visualized and analyzed in relation to environmental conditions such as sea surface temperature, salinity, and primary productivity. This will give the public, scientists, and resource managers an unprecedented ability to detect and communicate potential public and animal health risks in our changing ocean environment and to prioritize management and conservation efforts.


Marine Mammal Health MAP project

Is Marine Mammal Health Deteriorating? Trends in the Global Reporting of Marine Mammal Disease