Causes of strandings

Every year, many dolphins, whales and porpoises strand, worldwide. It is estimated that more than 10,000 whales, dolphins and porpoises have stranded worldwide since the British Museum started keeping records in 1913.

Strandings can occur for a number of reasons and they vary with each individual animal but some common causes are;

Disease
ranging from bacterial infections (pneumonia, gastroenteritis, meningitis, septicaemia) to parasitic infestations e.g. (lungworm) or viral disease such as morbillivirus

Trauma
due to serious wounds, dislocations or fractures

Malnutrition
in older animals and young calves, still dependent upon their mothers for food, that have become separated

Net entanglement (bycatch)
although few animals caught in nets rarely strand alive as they cannot escape and die

Strong social ties with their family pod
may also cause stranding, as many healthy animals will follow a sick, injured or diseased animal onto the beach

Navigational error
some marine mammals are known to use geomagnetic contours to navigate coastlines and where these cross a beach this can result in the animal following the contour line onto the beach or shoreline, (this can also occur during unusual weather patterns e.g. electrical storms)

Chasing prey
dolphins may strand while involved in chasing prey, they can unexpectedly be picked up by a wave and thrown onto a beach or be caught by receding tides

What to do / who to contact if you find a stranded cetacean

Anyone finding a dead marine mammal on their beach can help discover the cause of the stranding by reporting it to the relevant authorities. This enables them to address the issues adversely affecting these sea creatures. Stranding records are used to build up a picture of why strandings occur, causes of death and what can be done to help and reduce the numbers of marine wildlife that strand.

It is essential for people visiting, working or living near the coast to be extra vigilant and report any marine life in trouble. Anyone finding a dolphin, whale or any other marine animal washed up on a beach should report it immediately, speed is vital as if the animal is still alive it can be given assistance. Even if it is dead, it is still best to report this so the body can be collected before being swept back out to sea. If you find a stranded marine animal that is still alive, it is important to phone for expert advice but please note the following:

• It is essential to keep people and dogs away to reduce the stress caused to the animal
• Be careful - seals may bite when threatened and dolphins can make sudden movements
• Dolphins and whales need to be kept cool with seawater Carefully approach the animal. Be careful not to get water down its blowhole
• Do not pull on fins, tail-flukes or drag the animal back into the ocean
• Ensure that seals are genuinely beached; pups are often left while their mother goes off to feed

Alive (and in need of assistance)
BDMLR - 01825 765546

Dead
England : Natural History Museum - 020 7942 5155
Scotland : SAC Veterinary Services - 01463 243030
Wales : Marine Environment Monitoring - 01348 875000