2025 Report of Marine Mammal Strandings in the United States

NOAA Fisheries released the 2025 Report of Marine Mammal Strandings in the United States . In 2025, there were a total of 8,058 confirmed cetacean (whale, dolphin, and porpoise) and pinniped (seal, fur seal, and sea lion) strandings in the United States. This number is higher than the 2006-2024 average (6,422 + 1,159). A significant harmful algal bloom off southern California in early 2025 resulted in elevated strandings of sick and dead marine mammals (primarily California sea lions and common dolphins).

This is the seventh installment in a series of annual stranding reports compiled by the Marine Mammal Health and Stranding Response Program . Overviews for previous calendar years are also available:

What is a Stranding?

A marine mammal is considered stranded if it meets one of the following criteria:

• Dead, whether on the beach or floating in the water
• Alive, on a beach, but unable to return to the water
• Alive, on a beach, and in need of apparent medical attention
• Alive, in the water, and unable to return to its natural habitat without assistance

Not all pinnipeds on the beach are stranded . Seals, fur seals, and sea lions spend time on the beach to rest, molt, and breed.

Responding to stranding events is essential to minimize public health and safety risks from stranded marine mammals, support animal welfare, and gather data to inform science, management tools and decisions, and law enforcement investigations.

Why Do Marine Mammals Strand?

Marine mammals strand for a variety of reasons. Results from examinations and necropsies (animal autopsies) show common causes of strandings, include:

• Infectious diseases due to parasites, bacteria, fungi, and viruses
• Non-infectious diseases, including cancer
• Harmful algal blooms and associated biotoxins
• Injuries due to vessel collisions, entanglement in active and derelict fishing gear and marine debris, ingestion of marine debris or other human interactions, such as gunshots
• Malnutrition
• Pollution exposure
• Separation of pups and calves from their mothers
• Human disturbance or harassment
• A combination of these or other factors

Some strandings may also be related to unusual weather or oceanographic events such as hurricanes and tropical storms or marine heatwaves. In many cases the causes of a stranding event remain undetermined, especially when carcasses are found in advanced states of decomposition and examinations are limited.

How to report a stranded marine mammal

NOAA Fisheries' Marine Mammal Health and Stranding Response Program authorizes and oversees the U.S. Marine Mammal Stranding Response Network , These organizations are authorized under the Marine Mammal Protection Act to respond to-and in some cases rehabilitate -stranded marine mammals.

The Stranding Network relies on reports of stranded marine mammals by the public to save animals in distress and understand causes of injuries and mortalities. If you come across a stranded marine mammal, remain a safe and legal distance from the animal. Please report the animal to your regional 24/7 hotline . The most important information to collect is:

• Date and time
• Location of the stranding (including latitude and longitude, if known)
• Number of animals
• Condition of the animal (alive or dead)
• Species (if known)

Photos or videos from different angles and from a safe and legal distance (note that regulations apply to certain species and areas) can provide valuable information to Stranding Network responders. Stranded marine mammals are large, wild, unpredictable, and may have diseases that are transmissible to people. For these reasons-as well as legal requirements- only trained and authorized responders should approach, touch, or handle a stranded marine mammal . While we make every effort to respond to each stranded marine mammal, sometimes it is not possible (e.g., when human safety would be compromised).