Cetacean stranding

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A mass stranding of pilot whales on the shore of Cape Cod, 1902 Blackfish.jpg
A mass stranding of pilot whales on the shore of Cape Cod, 1902

Cetacean stranding, commonly known as beaching, is a phenomenon in which whales and dolphins strand themselves on land, usually on a beach. Beached whales often die due to dehydration, collapsing under their own weight, or drowning when high tide covers the blowhole. [1] Cetacean stranding has occurred since before recorded history. [2]

Contents

Several explanations for why cetaceans strand themselves have been proposed, including changes in water temperatures, [3] peculiarities of whales' echolocation in certain surroundings, [4] and geomagnetic disturbances, [5] but none have so far been universally accepted as a definitive reason for the behavior. However, a link between the mass beaching of beaked whales and use of mid-frequency active sonar has been found. [6]

Whales that die due to stranding can subsequently decay and bloat to the point where they can explode, causing gas and their internal organs to fly out.

Species

Beached false killer whales at Flinders Bay, Western Australia, 1986 1986 beached whales in Flinders Bay (2).JPG
Beached false killer whales at Flinders Bay, Western Australia, 1986

Every year, up to 2,000 animals beach themselves. [7] Although the majority of strandings result in death, they pose no threat to any species as a whole. Only about ten cetacean species frequently display mass beachings, with ten more rarely doing so.[ citation needed ]

All frequently-involved species are toothed whales (Odontoceti), rather than baleen whales (Mysticeti). These species share some characteristics which may explain why they beach.

Body size does not normally affect the frequency, but both the animals' normal habitat and social organization do appear to influence their chances of coming ashore in large numbers. Odontocetes that normally inhabit deep waters and live in large, tightly knit groups are the most susceptible. This includes the sperm whale, oceanic dolphins, usually pilot and Orcas, and a few beaked whale species. The most common species to strand in the United Kingdom is the harbour porpoise; the common dolphin ( Delphinus delphis ) is second-most common, and after that long-finned pilot whales ( Globicephala melas ). [8]

Solitary species naturally do not strand en masse. Cetaceans that spend most of their time in shallow, coastal waters almost never mass strand.

Causes

Strandings can be grouped into several types. The most obvious distinction is between single and multiple strandings. Many theories, some of them controversial, have been proposed to explain beaching, but the question remains unresolved.

Natural deaths at sea
The carcasses of deceased cetaceans are likely to float to the surface at some point; during this time, currents or winds may carry them to a coastline. Since thousands of cetaceans die every year, many become stranded posthumously. Offshore deaths of multiple whales are unlikely to lead to multiple strandings, since winds and currents are variable and will scatter a group of corpses. Most carcasses never reach the coast, and are scavenged, or decompose enough to sink to the ocean bottom, where the carcass forms the basis of a unique local ecosystem called a whale fall .
Individual strandings
Single live strandings are often the result of individual illness or injury; in the absence of human intervention these almost inevitably end in death.
Multiple strandings
Multiple strandings in one place are rare, and often attract media coverage as well as rescue efforts. The strong social cohesion of toothed whale pods appears to be a key factor in many cases of multiple stranding: If one gets into trouble, its distress calls may prompt the rest of the pod to follow and beach themselves alongside. [9]

Environmental

Three Beached Whales, a 1577 engraving by the Flemish artist Jan Wierix, depicts stranded sperm whales. Note the incorrectly recorded "nostril" and plausible extruded penis. Three Beached Whales, 1577.jpg
Three Beached Whales, a 1577 engraving by the Flemish artist Jan Wierix, depicts stranded sperm whales. Note the incorrectly recorded "nostril" and plausible extruded penis.
"The Whale beached between Scheveningen and Katwijk, with elegant sightseers", by Esaias van de Velde, c. 1617 The-whale-beached-1617.jpg
"The Whale beached between Scheveningen and Katwijk, with elegant sightseers", by Esaias van de Velde, c. 1617

Whales have beached throughout human history, with evidence of humans salvaging from stranded sperm whales in southern Spain during the Upper Magdalenian era some 14,000 years before the present. [2] Some strandings can be attributed to natural and environmental factors, such as rough weather, weakness due to old age or infection, difficulty giving birth, [9] hunting too close to shore, or navigation errors.

In 2004, scientists at the University of Tasmania linked whale strandings and weather, hypothesizing that when cool Antarctic waters rich in squid and fish flow north, whales follow their prey closer towards land. [3] In some cases predators (such as killer whales) have been known to panic other whales, herding them towards the shoreline. [3]

Their echolocation system can have difficulty picking up very gently-sloping coastlines. [10] This theory accounts for mass beaching hot spots such as Ocean Beach, Tasmania and Geographe Bay, Western Australia where the slope is about half a degree (approximately 8 m [26 ft] deep one km [0.62 mi] out to sea). The University of Western Australia Bioacoustics group proposes that repeated reflections between the surface and ocean bottom in gently sloping shallow water may attenuate sound so much that the echo is inaudible to the whales. [4] Stirred up sand as well as long-lived microbubbles formed by rain may further exacerbate the effect.

A 2017 study by scientists from Germany's University of Kiel suggests that large geomagnetic disruptions of the Earth's magnetic field, brought on through solar storms, could be another cause for whale beachings. [5] The authors hypothesize that whales navigate using the Earth's magnetic field by detecting differences in the field's strength to find their way. The solar storms cause anomalies in the field, which may disturb the whales' ability to navigate, sending them into shallow waters where they get trapped. [5] The study is based on the mass beachings of 29 sperm whales along the coasts of Germany, the Netherlands, the UK and France in 2016. [5]

"Follow-me" strandings

Mass stranding of dolphins, Nova Scotia (1918) Monsters of the deep No 1 Beached whales (HS85-10-34529).jpg
Mass stranding of dolphins, Nova Scotia (1918)

Some strandings may be caused by larger cetaceans following dolphins and porpoises into shallow coastal waters.[ citation needed ] The larger animals may habituate to following faster-moving dolphins. If they encounter an adverse combination of tidal flow and seabed topography, the larger species may become trapped.

Sometimes following a dolphin can help lead a whale out of danger: In 2008, a local dolphin was followed out to open water by two pygmy sperm whales that had become lost behind a sandbar at Mahia Beach, New Zealand. [11]

Orcas' intentional, temporary strandings

Pods of killer whales – predators of dolphins and porpoises – very rarely strand. It might be that killer whales have learned to stay away from shallow waters, and that heading to the shallows offers the smaller animals some protection from predators. However, killer whales in Península Valdés, Argentina, and the Crozet Islands in the Indian Ocean have learned how to operate in shallow waters, particularly in their pursuit of seals. The killer whales regularly demonstrate their competence by chasing seals up shelving gravel beaches, up to the edge of the water. The pursuing whales are occasionally partially thrust out of the sea by a combination of their own impetus and retreating water, and have to wait for the next wave to re-float them and carry them back to sea. [12]

A killer whale hunting sea lions at Valdes Peninsula, Argentina, by deliberately stranding itself Orcas in Punta Norte Valdes Peninsula - panoramio.jpg
A killer whale hunting sea lions at Valdes Peninsula, Argentina, by deliberately stranding itself

In Argentina, killer whales are known to hunt on the shore by intentionally beaching themselves and then lunging at nearby seals before riding the next wave safely back into deeper waters. This was first observed in the early 1970s, then hundreds times more since within this pod. This behavior seems to be taught from one generation to the next, evidenced by older individuals nudging juveniles towards the shore, and can sometimes also be a play activity. [12] [13] [14]

Sonar

Volunteers attempt to keep body temperatures of beached pilot whales from rising at Farewell Spit, New Zealand. Whales on beach, Farewell Split, South Island, New Zealand.JPG
Volunteers attempt to keep body temperatures of beached pilot whales from rising at Farewell Spit, New Zealand.

There is evidence that active sonar leads to beaching. On some occasions cetaceans have stranded shortly after military sonar was active in the area, suggesting a link. [6] Theories describing how sonar may cause whale deaths have also been advanced after necropsies found internal injuries in stranded cetaceans. In contrast, some who strand themselves due to seemingly natural causes are usually healthy prior to beaching:

The low frequency active sonar (LFA sonar) used by the military to detect submarines is the loudest sound ever put into the seas. Yet the U.S. Navy is planning to deploy LFA sonar across 80 percent of the world ocean. At an amplitude of two hundred forty decibels, it is loud enough to kill whales and dolphins and has already caused mass strandings and deaths in areas where U.S. and/or NATO forces have conducted exercises.

—  Whitty 2007, p. 50

Direct injury

The large and rapid pressure changes made by loud sonar can cause hemorrhaging. Evidence emerged after 17 cetaceans were hauled out in the Bahamas in March 2000 following a United States Navy sonar exercise. The Navy accepted blame agreeing that the dead whales experienced acoustically induced hemorrhages around the ears. [6] The resulting disorientation probably led to the stranding. Ken Balcomb, a cetologist, specializes in the killer whale populations that inhabit the Strait of Juan de Fuca between Washington and Vancouver Island. [15] He investigated these beachings and argues that the powerful sonar pulses resonated with airspaces in the dolphins, tearing tissue around the ears and brain. [16] Apparently not all species are affected by sonar. [17]

Injury at a vulnerable moment

Another means by which sonar could be hurting cetaceans is a form of decompression sickness. This was first raised by necrological examinations of 14  beaked whales stranded in the Canary Islands. The stranding happened on 24 September 2002, close to the operating area of Neo Tapon, an international naval exercise, about four hours after the activation of mid-frequency sonar. [18] The team of scientists found acute tissue damage from gas-bubble lesions, which are indicative of decompression sickness. [18]

The precise mechanism of how sonar causes bubble formation is not known. It could be due to cetaceans panicking and surfacing too rapidly in an attempt to escape the sonar pulses. There is also a theoretical basis by which sonar vibrations can cause supersaturated gas to nucleate, forming bubbles, which are responsible for decompression sickness. [19]

Diving patterns of Cuvier's beaked whales

The overwhelming majority of the cetaceans involved in sonar-associated beachings are Cuvier's beaked whales (Ziphius cavirostrus). Individuals of this species strand frequently, but mass strandings are rare.

Cuvier's beaked whales are an open-ocean species that rarely approach the shore, making them difficult to study in the wild. Prior to the interest raised by the sonar controversy, most of the information about them came from stranded animals. The first to publish research linking beachings with naval activity were Simmonds and Lopez-Jurado in 1991. They noted that over the past decade there had been a number of mass strandings of beaked whales in the Canary Islands, and each time the Spanish Navy was conducting exercises. Conversely, there were no mass strandings at other times. They did not propose a theory for the strandings. Fernández et al. in a 2013 letter to Nature reported that there had been no further mass strandings in that area, following a 2004 ban by the Spanish government on military exercises in that region. [20]

In May 1996, there was another mass stranding in West Peloponnese, Greece. At the time, it was noted as "atypical" both because mass strandings of beaked whales are rare, and also because the stranded whales were spread over such a long stretch of coast, with each individual whale spatially separated from the next stranding. At the time of the incident, there was no connection made with active sonar; A. Frantzis, the marine biologist investigating the incident, made the connection to sonar because he discovered a notice to mariners concerning the test. His report was published in March 1998. [21]

Peter Tyack, of Woods Hole Oceanographic Institute, has been researching noise's effects on marine mammals since the 1970s. He has led much of the recent research on beaked whales (Cuvier's beaked whales in particular). Data tags have shown that Cuvier's dive considerably deeper than previously thought, and are in fact the deepest-diving species of marine mammal yet known.

At shallow depths Cuvier's stop vocalizing, either because of fear of predators, or because they don't need vocalization to track each other at shallow depths, where they have light adequate to see each other.

Their surfacing behavior is highly unusual, because they exert considerable physical effort to surface by a controlled ascent, rather than passively floating to the surface as sperm whales do. Every deep dive is followed by three or four shallow dives. The elaborate dive patterns are assumed to be necessary to control the diffusion of gases in the bloodstream. No data show a beaked whale making an uncontrolled ascent, or failing to do successive shallow dives.[ citation needed ] This behavior suggests that the Cuvier's are in a vulnerable state after a deep dive – presumably on the verge of decompression sickness – and require time and perhaps the shallower dives to recover.

Summary review

De Quirós et al. (2019) [22] published a review of evidence on the mass strandings of beaked whale linked to naval exercises where sonar was used. It concluded that the effects of mid-frequency active sonar are strongest on Cuvier's beaked whales but vary among individuals or populations. The review suggested the strength of response of individual animals may depend on whether they had prior exposure to sonar, and that symptoms of decompression sickness have been found in stranded whales that may be a result of such response to sonar. It noted that no more mass strandings had occurred in the Canary Islands once naval exercises where sonar was used were banned, and recommended that the ban be extended to other areas where mass strandings continue to occur. [22] [23]

Disposal

A beachcomber inspects the carcass of a whale. The bite marks on the whale were made by a great white shark. A beachcomber is looking at the marks of great white sharks bites.jpg
A beachcomber inspects the carcass of a whale. The bite marks on the whale were made by a great white shark.
Memorial to beached whales outside Florence, Oregon Beached Whale Memorial, Florence, Oregon.jpg
Memorial to beached whales outside Florence, Oregon

If a whale is beached near an inhabited locality, the rotting carcass can pose a nuisance as well as a health risk. Such very large carcasses are difficult to move. The whales are often towed back out to sea away from shipping lanes, allowing them to decompose naturally, or they are towed out to sea and blown up with explosives. Government-sanctioned explosions have occurred in South Africa, Iceland, Australia and United States. [24] [25] [26] If the carcass is older, it is buried.

In New Zealand, which is the site of many whale strandings, treaties with the indigenous Māori people allow the tribal gathering and customary (that is, traditional) use of whalebone from any animal which has died as a result of stranding. Whales are regarded as taonga (spiritual treasure), descendants of the ocean god, Tangaroa, and are as such held in very high respect. Sites of whale strandings and any whale carcasses from strandings are treated as tapu sites, that is, they are regarded as sacred ground. [27]

Health risks

A beached whale carcass should not be consumed. In 2002, fourteen Alaskans ate muktuk (whale blubber) from a beached whale, resulting in eight of them developing botulism, with two of the affected requiring mechanical ventilation. [28] This is a possibility for any meat taken from an unpreserved carcass.

Large strandings

This is a list of large cetacean strandings (200 or more).

TotalDeathsSurvivedDateIncidentLocation
1,0001,00001918Largest pilot whale stranding ever recorded. [29] Flag of New Zealand.svg Chatham Islands, New Zealand
6563353212017About 650 pilot whales beached themselves at the top of South Island, killing 335 of them. The others were able to swim away at high tide or were refloated by volunteers. [30] [31] [32] Flag of New Zealand.svg South Island, New Zealand
500+500+01897More than 500 pilot whales died at Teal Inlet. [33] Flag of the Falkland Islands.svg Teal Inlet, Falkland Islands
4703621082020About 270 pilot whales were found at Macquarie Heads on September 21, followed by the discovery of 200 dead whales two days later about 10 kilometers south, raising the total to 470. Only 108 were rescued. [34] [35] Flag of Australia (converted).svg Tasmania, Australia
±300±75±2251985Nearly 300 pilot whales ran aground on Great Barrier Island, killing about one-quarter of them. Local residents, who had received rescue lectures after a similar incident the previous year, helped rescue more than 200 whales at high tide. [36] Flag of New Zealand.svg Great Barrier Island, New Zealand
29424549+1935Around 300 pilot whales were stranded at Stanley, Tasmania. [37] [38] [39] The exact number of deaths or whales involved is unclear, with one newspaper reporting at least 245 confirmed deaths, [40] while another newspaper reported in 1936 that 70 whales escaped during high tide the day after the stranding. [41] Flag of Australia (converted).svg Tasmania, Australia
25325301978More than 250 false killer whales stranded and died near Pukekohe. [42] Flag of New Zealand.svg North Island, New Zealand
24024002022About 240 pilot whales beached themselves at Walhere Bay on Pitt Island, just 3 days after 240 pilot whales beached themselves at nearby Chatham Island. [43] Flag of New Zealand.svg Pitt Island, New Zealand
24024002022About 240 pilot whales beached themselves in the northwest of Chatham Island, just 3 days before 240 whales beached themselves at nearby Pitt Island. [43] Flag of New Zealand.svg Chatham Island, New Zealand
230195352022About 230 pilot whales beached themselves on the west coast of Tasmania, exactly two years to the day of another mass stranding in the same area. [44] Flag of Australia (converted).svg Tasmania, Australia

Others

On June 23, 2015, 337 dead whales were discovered in a remote fjord in Patagonia, southern Chile, the largest stranding of baleen whales to date. [45] Three hundred and five bodies and 32 skeletons were identified by aerial and satellite photography between the Gulf of Penas and Puerto Natales, near the southern tip of South America. They may have been sei whales. [46] This is one of only two or three such baleen mass stranding events in the last hundred years. It is highly unusual for baleen whales to strand other than singly, and these Patagonia strandings are tentatively attributed to an unusual cause such as ingestion of poisonous algae.

In November 2018, over 140 whales were witnessed stranded on a remote beach in New Zealand and had to be euthanised because of their declining health condition. [47] In July 2019, nearly 50 long-finned pilot whales were found stranded on Snaefellsnes Peninsula in Iceland. However, they were already dead when spotted. [48]

On the evening of November 2, 2020, over 100 short-finned pilot whales were stranded on the Panadura Beach in western coast of Sri Lanka. [49] Four deaths were reported, and all other whales were rescued. [50]

See also

Related Research Articles

<span class="mw-page-title-main">Cetacea</span> Infraorder of mammals

Cetacea is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movement of their tail which ends in a paddle-like fluke, using their flipper-shaped forelimbs to maneuver.

<span class="mw-page-title-main">Beaked whale</span> Family of mammals

Beaked whales are a family of cetaceans noted as being one of the least-known groups of mammals because of their deep-sea habitat, reclusive behavior and apparent low abundance. Only three or four of the 24 existing species are reasonably well-known. Baird's beaked whales and Cuvier's beaked whales were subject to commercial exploitation, off the coast of Japan, while the northern bottlenose whale was extensively hunted in the northern part of the North Atlantic in the late 19th and early 20th centuries.

<span class="mw-page-title-main">Risso's dolphin</span> Species of marine mammal

Risso's dolphin is a dolphin, the only species of the genus Grampus. Some of the closest related species to these dolphins include: pilot whales, pygmy killer whales, melon-headed whales, and false killer whales.

<span class="mw-page-title-main">Spectacled porpoise</span> Species of mammal

The spectacled porpoise is a small to midsize porpoise indigenous to the Southern Ocean. It is one of the most poorly studied cetaceans, partly due to its remote range in the Southern Ocean. What little is known about this porpoise species has been gathered mainly from stranded individuals, and a few observations of living animals made at sea.

<span class="mw-page-title-main">Sowerby's beaked whale</span> Species of mammal

Sowerby's beaked whale, also known as the North Atlantic or North Sea beaked whale, is a species of toothed whale. It was the first mesoplodont whale to be described. James Sowerby, an English naturalist and artist, first described the species in 1804 from a skull obtained from a male that had stranded in the Moray Firth, Scotland, in 1800. He named it bidens, which derives from the two teeth present in the jaw, now known to be a very common feature among the genus.

<span class="mw-page-title-main">Blainville's beaked whale</span> Species of mammal

Blainville's beaked whale, or the dense-beaked whale, is believed to be the widest ranging mesoplodont whale. The French zoologist Henri de Blainville first described the species in 1817 from a small piece of jaw — the heaviest bone he had ever come across — which resulted in the name densirostris. Off the northeastern Bahamas, the animals are particularly well documented, and a photo identification project started sometime after 2002.

<span class="mw-page-title-main">Hector's beaked whale</span> Species of mammal

Hector's beaked whale, is a small mesoplodont living in the Southern Hemisphere. This whale is named after Sir James Hector, a founder of the colonial museum in Wellington, New Zealand. The species has rarely been seen in the wild.

<span class="mw-page-title-main">Strap-toothed whale</span> Species of whale

The strap-toothed beaked whale, also known as Layard's beaked whale, is one of the largest members of the Mesoplodon genus, growing to 6.2 m (20 ft) in length and reaching up to 1,300 kg (2,900 lb). The common and scientific name was given in honor of Edgar Leopold Layard, the curator of the South African Museum, who prepared drawings of a skull and sent them to the British taxonomist John Edward Gray, who described the species in 1865.

<span class="mw-page-title-main">Short-finned pilot whale</span> Species of mammal

The short-finned pilot whale is one of the two species of cetaceans in the genus Globicephala, which it shares with the long-finned pilot whale. It is part of the oceanic dolphin family (Delphinidae).

<span class="mw-page-title-main">Pilot whale</span> Genus of dolphins in the order Cetacea

Pilot whales are cetaceans belonging to the genus Globicephala. The two extant species are the long-finned pilot whale and the short-finned pilot whale. The two are not readily distinguishable at sea, and analysis of the skulls is the best way to distinguish between the species. Between the two species, they range nearly worldwide, with long-finned pilot whales living in colder waters and short-finned pilot whales living in tropical and subtropical waters. Pilot whales are among the largest of the oceanic dolphins, exceeded in size only by the orca. They and other large members of the dolphin family are also known as blackfish.

<span class="mw-page-title-main">Cuvier's beaked whale</span> Species of whale

Cuvier's beaked whale, goose-beaked whale, or ziphius is the most widely distributed of all beaked whales in the family Ziphiidae. It is smaller in size than most baleen whales—and indeed the larger toothed cetaceans —yet it is large among the beaked whales and smaller cetaceans, appearing somewhat like a bigger and stockier bottlenose dolphin. Cuvier's beaked whale is pelagic, generally inhabiting waters deeper than 300 m (1,000 ft), though it has been observed closer to shore on occasion. In these offshore waters, Cuvier's beaked whale executes some of the deepest, longest recorded dives among whales, and extant mammals, at 2,992 m (9,816 ft), for 222 minutes. While likely diving to forage and hunt prey, such as cephalopods, and potentially evade predators, the frequency and exact reason for these extraordinary dives is unclear. Despite its deepwater habitat, it is one of the most frequently-spotted beaked whales when surfacing.

<i>Berardius</i> Genus of mammals

The four-toothed whales or giant beaked whales are beaked whales in the genus Berardius. They include Arnoux's beaked whale in cold Southern Hemispheric waters, and Baird's beaked whale in the cold temperate waters of the North Pacific. A third species, Sato's beaked whale, was distinguished from B. bairdii in the 2010s.

<span class="mw-page-title-main">Shepherd's beaked whale</span> Species of mammal

Shepherd's beaked whale, also commonly called Tasman's beaked whale or simply the Tasman whale, is a cetacean of the family Ziphiidae and the only species in the genus Tasmacetus. The whale has not been studied extensively. Only four confirmed at sea sightings have been made and 42 strandings recorded. It was first known to science in 1937, being named by W. R. B. Oliver after George Shepherd, curator of the Wanganui Museum, who collected the type specimen near Ohawe on the south Taranaki coast of New Zealand's North Island, in 1933.

<span class="mw-page-title-main">False killer whale</span> Species of oceanic dolphin in the genus Pseudorca

The false killer whale is a species of oceanic dolphin that is the only extant representative of the genus Pseudorca. It is found in oceans worldwide but mainly in tropical regions. It was first described in 1846 as a species of porpoise based on a skull, which was revised when the first carcasses were observed in 1861. The name "false killer whale" comes from having a skull similar to the orca, or killer whale.

<span class="mw-page-title-main">Melon-headed whale</span> Species of mammal

The melon-headed whale, also known less commonly as the electra dolphin, little killer whale, or many-toothed blackfish, is a toothed whale of the oceanic dolphin family (Delphinidae). The common name is derived from the head shape. Melon-headed whales are widely distributed throughout deep tropical and subtropical waters worldwide, but they are rarely encountered at sea. They are found near shore mostly around oceanic islands, such as Hawaii, French Polynesia, and the Philippines.

<span class="mw-page-title-main">Southern right whale dolphin</span> Species of mammal

The southern right whale dolphin is a small and slender species of cetacean, found in cool waters of the Southern Hemisphere. It is one of two species of right whale dolphin. This genus is characterized by the lack of a dorsal fin. The other species, the northern right whale dolphin, is found in deep oceans of the Northern Hemisphere and has a different pigmentation pattern than the southern right whale dolphin.

<span class="mw-page-title-main">Marine mammals and sonar</span>

The interactions between marine mammals and sonar have been a subject of debate since the invention of the technology.

<span class="mw-page-title-main">Cetacean strandings in Ghana</span>

Cetacean strandings in Ghana appear to be becoming more common. Whales washing ashore may be due to ship strike, population dynamics, or an increase in human coverage and reporting. There are at least 28 species of cetaceans — seven baleen whales and 21 toothed whales — in the Gulf of Guinea, of which Ghana’s coast covers 550 km from Aflao to Axim. Scientific approaches to cetacean diversities have not been taken until recently, and 18 species were confirmed during researches.

Cetaceans form an infra-order of marine mammals. In 2020, approximately 86 species of cetaceans had been identified worldwide. Among these species, at least 35 have been sighted in the wider Caribbean region with very widespread distribution and density variations between areas. Caribbean waters are a preferred breeding site for several species of mysticeti, who live further north the rest of the year. The tucuxi and the boto live at the southern periphery of the Caribbean region in the freshwaters of the Amazon River and surrounding drainage basins.

<span class="mw-page-title-main">Natacha Aguilar de Soto</span> Spanish marine biologist

Natacha Aguilar de Soto is a Spanish marine biologist at the University of La Laguna (ULL), Tenerife, Canary Islands. She is a Ramón y Cajal research and teaching fellow at ULL and has been a Marie Skłodowska-Curie Research Fellow at ULL and at the Center for Research in Ecological Modeling (CREEM) of the University of St. Andrews (SMRU). She is the director of cetacean research within ULL's BIOECOMAC.

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  13. ↑ Guinet, C. (1991). "Intentional stranding apprenticeship and social play in killer whales (Orcinus orca)". Canadian Journal of Zoology. 69 (1): 2712–2716. doi:10.1139/z91-383.
  14. ↑ Kaplan, Matt (2007). "Unique orca hunting-technique documented". Nature. News. doi:10.1038/news.2007.380.
  15. ↑ Balcomb, Ken (2003-05-12). "U.S. Navy sonar blasts Pacific Northwest killer whales". San Juan Islander. Archived from the original on 23 May 2006. Retrieved 2006-04-30.
  16. ↑ Balcomb, Ken (2001-02-23). "Letter". Ocean Mammal Institute. Archived from the original on 25 May 2006. Retrieved 2006-04-30.
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  18. 1 2 Jepson, P.D.; Arbelo, M.; Deaville, R.; Patterson, I.A.P.; Castro, P.; Baker, J.R.; et al. (9 October 2003). "Gas-bubble lesions in stranded cetaceans". Nature. 425 (6958): 575–576. Bibcode:2003Natur.425..575J. doi:10.1038/425575a. PMID   14534575. S2CID   26717950.
  19. ↑ Houser, D.S.; Howards, R.; Ridgway, S. (21 November 2001). "Can diving-induced tissue nitrogen supersaturation increase the chance of acoustically driven bubble growth in marine mammals?". Journal of Theoretical Biology. 213 (2): 183–195. Bibcode:2001JThBi.213..183H. doi:10.1006/jtbi.2001.2415. PMID   11894990. S2CID   19130432.
  20. ↑ Fernández, A.; Arbelo, M.; Martín, V. (2013). "Whales: No mass strandings since sonar ban". Nature. 497 (7449): 317. Bibcode:2013Natur.497..317F. doi: 10.1038/497317d . PMID   23676745.
  21. ↑ Frantzis, A. (1988-03-05). "Does acoustic testing strand whales?". Nature . 392 (6671): 29. doi: 10.1038/32068 . PMID   9510243. S2CID   205001662.
  22. 1 2 Bernaldo de Quirós, Y.; Fernandez, A.; Baird, R.W.; Brownell, Jr., R.L.; Aguilar de Soto, N.; Allen, D.; Arbelo, M.; Arregui, M.; Costidis, A.; Fahlman, A.; Frantzis, A.; Gulland, F.M.D.; Iñíguez, M.; Johnson, M.; Komnenou, A.; Koopman, H.; Pabst, D.A.; Roe, W.D.; Sierra, E.; Tejedor, M.; Schorr, G. (30 January 2019). "Advances in research on the impacts of anti-submarine sonar on beaked whales". Proceedings of the Royal Society B. 286 (1895): 20182533. doi:10.1098/rspb.2018.2533. PMC   6364578 . PMID   30963955.
  23. ↑ Batchelor, Tom (30 January 2019). "Scientists demand military sonar ban to end mass whale strandings". The Independent .
  24. ↑ "Exploding Whale - Whale Of A Tale". 29 April 2011. Archived from the original on 2021-11-18 – via YouTube.
  25. ↑ "Hvalhræ dregið út á haf og síðan aftur upp í fjöru" [Whale pulled out to sea and then back up the beach]. mbl.is (in Icelandic). June 5, 2005. Retrieved July 17, 2013.
  26. ↑ "Explosive end for sick whale". ABC News . September 2, 2010. Retrieved September 22, 2020.
  27. ↑ Te Karaka, "The science of strandings', Te Rūnanga o Ngāi Tahu, 21 December 2014. Retrieved 12 February 2017.
  28. ↑ Middaugh, J; Funk, B; Jilly, B; Maslanka, S; McLaughlin J (2003-01-17). "Outbreak of Botulism Type E Associated with Eating a Beached Whale --- Western Alaska, July 2002". Morbidity and Mortality Weekly Report. 52 (2): 24–26. PMID   12608715.
  29. ↑ More than 200 pilot whales euthanised after stranding on Chatham Islands
  30. ↑ Dwyer, Colin (11 February 2017). "As 200 More Whales Are Stranded In New Zealand, Heroics Turn To Heartbreak". NPR.
  31. ↑ Davey, Melissa (12 February 2017). "Hope for end to New Zealand whale strandings after 350 die". The Guardian.
  32. ↑ "New Zealand whales: Hundreds refloat on high tide at Farewell Spit". BBC News. 12 February 2017.
  33. ↑ Stranding of whales at the Falkland Islands
  34. ↑ Hope saved pilot whales in Tasmania can reunite at sea
  35. ↑ Update on the tragic pilot whale stranding in Tasmania
  36. ↑ "Stranded Whales Driven Back Into Sea". Los Angeles Times . 1985-08-08. Archived from the original on 2022-10-13.
  37. ↑ "Beach at Stanley Strewn With Whales". The Examiner (Tasmania) . Vol. XCIV, no. 184. 15 October 1935. p. 7 (DAILY). Retrieved 23 September 2020– via National Library of Australia.
  38. ↑ "300 Whales Stranded". The Mercury . Vol. CXLIII, no. 20, 272. 15 October 1935. p. 7. Retrieved 23 September 2020– via National Library of Australia.
  39. ↑ "The Whales at Stanley will be buried". The Examiner (Tasmania) . Vol. XCIV, no. 187. 16 October 1935. p. 7 (DAILY). Retrieved 23 September 2020– via National Library of Australia.
  40. ↑ "Burying Whales". The Mercury . Vol. CXLIII, no. 20, 277. 21 October 1935. p. 11. Retrieved 23 September 2020– via National Library of Australia.
  41. ↑ A Whale of a Query
  42. ↑ Theory on dead whales
  43. 1 2 "Nearly 500 pilot whales die in New Zealand beachings". BNO News . October 10, 2022. Retrieved October 10, 2022.
  44. ↑ Desperate rescue mission to save stranded Tasmanian pod ends with 35 successfully returned to the ocean
  45. ↑ "Apocalypse video: more than 300 whales found dead in Patagonia! Politicians must take Now strict measures to protect more our Oceans!". Arctic05. Retrieved 2021-10-11.
  46. ↑ Howard, Brian Clark; National Geographic (20 November 2015). "337 Whales Beached in Largest Stranding Ever". National Geographic News. Archived from the original on November 21, 2015. Retrieved 2015-11-21.
  47. ↑ "More than 140 whales die after mass stranding on remote New Zealand beach". ABC News (Australia). 26 November 2018. Retrieved 22 September 2020.
  48. ↑ "Dozens of pilot whales found dead after mass stranding on remote Iceland beach". ABC News. 20 July 2019.
  49. ↑ "Largest whale stranding in Sri Lanka draws epic volunteer rescue effort". News First. 3 November 2020. Retrieved 3 November 2020.
  50. ↑ Karunatilake, Waruna (3 November 2020). "Sri Lankan navy, villagers rescue more than 100 stranded whales". Reuters . Retrieved 3 November 2020.
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