Why do whales and dolphins strand?

What is a stranding?

According to the U.S. Marine Mammal Protection Act, a stranded marine mammal is not only a living marine mammal on land that needs medical assistance or is unable to return to the water without assistance, but also includes any dead marine mammal (at sea or on land). And while it’s fairly easy to determine if a whale or dolphin is stranded, it’s rarely easy to understand why.
Stranded pilot whales

Fascinating Fact

There is a species of beaked whale, Perrin’s beaked whale, that was first identified from a few stranded individuals and has only recently been seen at sea!

Types of strandings

Single Strandings

This can include a living or dead baleen or toothed whale species and includes either a single individual or a mother and her calf.  Since a calf is still dependent on his or her mom, stranding with mom is considered a single event.

Spirtle survived a stranding on a beach

Mass Strandings

Mass strandings primarily occur when 2 or more (not including a mom and calf) whales or dolphins strand together.  These are typically social groups of toothed whales (dolphins, pilot whales, sperm whales, etc) who are usually alive when the stranding occurs.

Navigational Errors

Whales and dolphins are more likely to strand on some types of shore and coastline than others. Shallow, sloping shores made of soft sediment can confuse the “echolocation” used by whales and dolphins to find their way around.

A combination of factors may cause whales and dolphins to strand and one theory relates to them navigating using the earth’s magnetic field. Crystals of magnetite - which react to a weak magnetic field - have been detected in the brains and skulls of some whales and dolphins and a magnetic “sense” could be an important navigational aid, especially in the deep oceans.

Whether caused by human activity or as a result of something natural, strandings are tragic, but they, can tell us a lot, about the biology of the animals, the state of the population it came from and the marine environment.

What to do if you find a stranded whale or dolphins?

WDC staff attend and help with many live strandings, and lots of ‘dead’ ones too. Our experts are often involved in the post-mortem examination. It’s a grisly task, but we do it, because it gives us information: Information we use to get conservation measures put in place.

A live whale or dolphin beached on the shore is almost always in danger of its life. If you find a stranded whale or dolphin, whether it is alive or dead, please report it as soon as possible.

If you find a LIVE stranded or injured whale, dolphin or porpoise on the beach or in the shallows, you must act quickly. The appropriate emergency numbers to call in such an event and which can be used 24 hours a day are:

England and Wales

1. 01825 765 546 (BDMLR - British Divers Marine Life Rescue)


2. 08705 555 999 (RSPCA - Royal Society for the Prevention of Cruelty to Animals)

Please try to give as accurate a location and description of the stranded animal as possible.

DEAD stranded cetaceans and seals (in any condition) can also be reported, to allow the bodies to be examined to try to determine causes of death and collect other important information. If possible, secure the carcass above the high water mark, and take as accurate information possible about the location and description of the animal.

Then you can call the UK Strandings Hotline (freephone number) on 0800 652 0333 or visit http://ukstrandings.org


The appropriate emergency numbers to call and which can be used 24 hours a day are:

1. 01825 765 546 (BDMLR - British Divers Marine Life Rescue)


2. 03000 999 999 (SSPCA - Scottish Society for the Prevention of Cruelty to Animals Hotline)

If the animal is DEAD then contact the Scottish Strandings Co-ordinator at the Scottish Agricultural College on: 01463 243030 or 07979 245893 (email: strandings@sruc.ac.uk).

Northern Ireland & the Republic of Ireland

The appropriate emergency numbers to call and which can be used 24 hours a day are:

Northern Ireland - 08 0232 381251

Republic of Ireland - 021 904197 or 021 904053

If you find a live stranded seal contact the Irish Seal Sanctuary on: 01 8354370 or mobile 087 2333406

Please help us saves whales and dolphins

By adopting a whale or dolphin, by making a donation, or by fundraising for WDC, you can help us save these amazing creatures.

Orca - Rob Lott


Adopt a whale or dolphin and help us to understand the causes of strandings.

Bottlenose dolphins leaping


Your gifts will enable us to attend strandings and assist at post-mortems.

Humpback whale spyhop


Run, bake, walk, cycle… what could you do to help?