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FAQs: Whale, Dolphin, Seal, and Sea Lion (Marine Mammal) Strandings

Why do marine mammals strand?
In most stranding cases, the cause of stranding is unknown, but some identified causes include:

In addition, strandings often occur after unusual weather or oceanographic events.

In the past few years, increased efforts in examining carcasses and live stranded animals has increased our knowledge of mortality rates and causes, allowing us to better understand population threats and pressures.

What information is gained from necropsies of stranded marine mammals?
If a stranded marine mammal has recently died, then a significant amount of valuable information can be gained from it. For instance:

These types of sampling opportunities also help validate and increase understanding and interpretation of data collected from wild populations.

Through necropsies we have learned a significant amount about the basic physiology and biology of animals that are not accessible in the wild or through any other means.

Necropsies have also provided data on the incidence of human interactions including:

These data help us to make better management decisions about these stocks of marine mammals.

How many marine mammal strandings occur?
Over the 9-year period from 2001-2009:

Region Cetacean Strandings Pinniped Strandings Total
Marine Mammal Strandings
Northeast 3,663 7,873 11,536
Southeast 5,872 98 5,970
Southwest 1,591 25,308 26,899
Northwest 588 5,193 5,781
Alaska 673 556 1,229
Pacific Islands 158 76 234
U.S. Totals 12,545 39,104 51,649

How many marine mammal rehabilitation facilities are there in the United States?
There are currently 32 facilities that can rehabilitate stranded marine mammals under NMFS jurisdiction. In all, there are over 120 organizations or stranding network participants authorized by NMFS to respond to marine mammal strandings, but only some of those facilities can rehabilitate marine mammals.

There are many organizations/stranding network participants who are strictly first responders on the beach (i.e., they rescue the animal, but don't have adequate facilities to rehabilitate marine mammals).

Some network participants respond only to dead marine mammal strandings. Responders to dead strandings make up the vast majority of responders and may include Federal, state, and local governmental entities, non-profit organizations, academic institutions, museums, scientists, and managers among others.

NMFS oversees marine mammal stranding response through a Regional Stranding Coordinator in all 6 of NMFS' regions.

What is the scope of the Marine Mammal Health and Stranding Response Program?
Marine mammal stranding networks in the United States make up one facet of a broader, more comprehensive program called the Marine Mammal Health and Stranding Response Program (MMHSRP), established in the late 1980s in response to growing concern about marine mammals washing ashore in U.S. waters. The MMHSRP's goals are to:

This program was formalized by the 1992 Amendments to the Marine Mammal Protection Act, and the National Marine Fisheries Service (NMFS) was designated as the lead agency to coordinate related activities. The program has the following components: