Why whales strand: The story of Humpy the humpback whale found dead on Northumberland beach

Isabel Lamb explains the science behind whale strandings with exclusive images of Humpy the humpback whale from March's stranding in Blyth

Isabel Lamb
8th May 2021
Image Credit: Claire Dowens
On the 19th March 2021, an 11 month old humpback whale was washed up on a beach near Blyth, Northumberland. The whale, known as Humpy, was spotted dead out to sea several weeks previously but was believed to still be alive around February time. When seen dead out to sea, Humpy was entangled in rope, but it is still to be determined if this killed Humpy or occurred post-mortem.

Sightings of adult and juvenile humpback whales along the Northumberland coast are rare but not unheard of. Humpbacks pass through UK waters as they migrate from their feeding grounds near the poles to the warmer breeding waters near the equator. The number of sightings in the North Sea has been rising in recent years.  

As numbers rise, there are likely to be more incidences of entanglement which can lead to whale strandings

There are several possible explanations for this recent resurgence: humpbacks are attracted to the easier food access as herring stocks increase; higher, more desirable water temperatures mean whales remain in the area for longer; or a general recovery of humpback population size has led to more frequent sightings following the ban on commercial whaling in the 1980s.

Image Credit: amanda panda on Unsplash

Individual humpbacks can be identified by the unique patterns on their tail flukes. Photos sent in by members of the public can be used by the academics of wildlife monitoring groups to track humpbacks. This is how Humpy was known to be alive back in February.

The use of high-powered sonar for maritime navigation causes noise pollution that can confuse or distract the whales

As numbers rise there are likely to be more incidences of entanglement alongside more cetacean (aquatic mammal) strandings, known as beachings. Whales who wash ashore dead from unnatural causes may have perished due to interactions with shipping vessels, that caused them physical harm or entanglement in fishing ropes. Beachings where whales were not already deceased are usually the result of sickness, injury, or whales who are pushed ashore by the currents whilst in a weakened state.

Some scientists suggest the use of high-powered sonar for maritime navigation causes noise pollution that confuses or distracts the whales and in their befuddled state, they accidentally become stuck in waters too shallow to escape.

When Humpy stranded back in March, The Courier's own Claire Dowens was at the scene on Blyth beach to take photographs.

Image Credit: Claire Dowens

There are also incidents of mass beachings, not among humpbacks who are solitary or interact in mother-calf pairings, but among cetacean species that live in pods. Some scientists lean towards a social care hypothesis whereby healthy whales will beach themselves to remain in contact with sick relatives. However, mass beachings can occur with whales who share no genetic relation and therefore such behaviour may not be altruistic.

Another possibility is related to the matrilineal structure of pods. Members of a pod tend to follow a matriarch and consequently may even follow her into shallow waters if she enters them by accident whilst in a sick or confused state. However, some scientists note that pods rarely beach in a simultaneous event. Rather, larger pods are usually formed of subgroups, who beach one after the other rather than all at once.

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