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Peter Evans does not work for, consult, own shares in or receive sầu funding from any company or organization that would benefit from this article, & has disclosed no relevant affiliations beyond their academic appointment.

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Although it’s tempting to automatically blame whale strandings on human activity, the fact that deep-dwelling species of whales most often get stranded, và in the same locations, indicates that in many cases natural causes are more likely lớn be khổng lồ blame. Mass strandings of these oceanic species tover to lớn be in very shallow areas with gently sloping, often sandy, seabeds. In those situations, it is no surprise that these animals, which are used khổng lồ swimming in deep waters, can get inlớn difficulties & even if re-floated will often re-str&.

The echolocation they use khổng lồ aid navigation also does not work well in such environments. So it is quite possible that the majority of such strandings are simply due khổng lồ navigational error, for example when whales have followed a valuable prey resource into unfamiliar & dangerous territory. This may have sầu been the cause of the mass stranding of sperm whales in the North Sea, some of which had recently digested oceanic squid in their stomachs.

The ratio of strandings lớn sightings for sperm whales in the North Sea is significantly higher south of the Dogger Bank where shallow, often sandy, environments prevail. And the same goes for Farewell Spit, Golden Bay in the South Island of New Zealvà, where the recent pilot whale stranding took place & where similar incidents have sầu occurred several times in the last few years.

Deadly consequences. Remko de Waal/EPA

Both areas have seen a number of mass strandings of those particular species in the past. In the southern North Sea, there are records of mass strandings of sperm whales dating bachồng at least lớn 1577.

However, mass strandings aren’t only caused by whales getting lost or misjudging the depth of the water. One or more individuals may be diseased and, as they become weaker, they seek shallower waters so they can more easily come khổng lồ the surface to lớn breathe. Once their bodies come khổng lồ rest on a hard surface for any extended period, there is a greatly increased chance that their chest walls will be compressed and their internal organs damaged.

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Sonar effects

Occasionally, live sầu strandings may derive from human activities, particularly military activity that involves the use of sonar. This connection was first suggested in 1996 after a NATO military exercise off the coast of Greece coincided with the stranding of 12 Cuvier’s beaked whales. Unfortunately, there was no opportunity for veterinary examination.

But in May 2000, another beaked whale mass stranding took place in the Bahamas alongside naval activity using similar loud mid-frequency sonar. A number of the whales were examined, & haemorrhaging, particularly around the inner ear, was discovered, indicating acoustic trauma.

After a similar incident in the Canary Islands in September 2002, veterinary pathologists analysing the whales also identified symptoms of decompression sickness. This suggests that the animals vì chưng not always die from stranding but may be injured or die at sea first. Many researchers now believe sầu that naval sonar might produce behaviour in whales that interferes with their ability khổng lồ manage the gases inside their bodies, affecting their ability khổng lồ dive & rise to lớn the surface safely.

Loud noise in the ocean has become a major conservation concern as humans introduce sounds of varying intensities and frequencies into the marine environment from different technologies & even explosions. Seaquakes are another source of intense underwater sound & those might also lead to physical damage or behaviour resulting in strandings, although no one has yet produced a statistical links between the two.

Social following

The kind of strandings seen in New Zealvà, where very large numbers of whales become beached but a significant proportion can be rescued, also raises the question of whether some healthy animals simply follow others inkhổng lồ dangerously shallow waters.

Many years ago, I went lớn the aid of two short-beaked comtháng dolphins that stranded alive in the Teifi Estuary, west Wales. One of the individuals died quite quickly và a subsequent post-mortem revealed it had a heavy lung parasite infection, which was thought to have affected breathing. The other individual remained cthua to lớn its dying companion và appeared to lớn be in great dicăng thẳng, whistling frequently.

We managed to successfully refloat this other dolphin in the kết thúc & it swam away, but the incident highlighted to lớn me the strong social bonds that can exist between individuals. When we see large numbers of whales or dolphins undertaking what appears to be mass suicide, the chances are that they are vocally responding khổng lồ one another, reflecting their strong sociality.

Recent research suggests that whales in mass strandings aren’t necessarily even related to lớn one another. So perhaps mass strandings are a reflection of just how strong the social bonds between whales really are.