New Zealand blue whales, new research

This video is called Whales: Giants of the Deep.

From Wildlife Extra:

Blue whales are feeding off New Zealand, not just migrating

Blue whales believed to be foraging in South Taranaki Bight

May 2013. A recent study indicates that Blue whales in a coastal area of New Zealand, known as the South Taranaki Bight, might be doing more than just passing through on their way to and from summer feeding grounds in Antarctica.

Extensive study

A new study, carried out by the National Institute for Water and Atmospheric Research (NIWA), examined opportunistic sightings of Blue whales collected between 1979 and 1999, historical whaling data, stranding events, foraging observations, and sightings recorded during two seismic surveys conducted in 2011.

High density of Blue whales

The findings show that the presence of Blue whales in the South Taranaki Bight is greater than expected and historical whaling data demonstrate a high density of Blue whales in the region throughout time. The study links this increased presence of Blue whales in the Bight to the prominent upwelling system near the South Island’s Farewell Spit that generates large clouds of plankton – perfect Blue whale food – in the South Taranaki Bight.

Very elusive

Despite being more than 20 metres in length and weighing more than 100 tonnes, the Blue whale remains one of the world’s most elusive creatures. Southern Hemisphere Blue whales were intensively hunted during the whaling era, leaving only small populations behind. Sightings are rare and little is known about the distribution patterns of Blue whales, the world’s largest animal.

NIWA marine ecologist Dr Leigh Torres said that the study would significantly enhance people’s understanding of the distribution and foraging grounds of Blue whales in the Southern Hemisphere.

Feeding, not migrating

“Conventional wisdom has been that Blue whales only transit through New Zealand waters while migrating. But this new information suggests that this is not an accurate understanding of their ecology. Blue whales appear to be present in the South Taranaki Bight with some regularity and density, and based on their foraging patterns and the availability of their prey in the area, we think they are feeding here.”

Just four Blue whale foraging grounds in the Southern Hemisphere outside of Antarctic waters!

“Blue whales are huge and need to eat vast amounts of food, which are tiny plankton, to support their energy demands. But there are just four confirmed Blue whale foraging grounds in the Southern Hemisphere outside of Antarctic waters. So, it’s very important that we properly document and protect their foraging grounds.”

Currently, the Blue whale is classified as a “migrant” under the New Zealand Threat Classification System, which means they aren’t afforded the same level of conservation protections as other large baleen whales that use coastal waters around New Zealand such as the southern right whale.

Dr Torres said that, although further work was necessary to determine the scale and significance of the foraging ground in the South Taranaki Bight, the new information may prompt a rethink on how Blue whales are classified in New Zealand.

Largest offshore natural gas and oil exploration area in New Zealand

“The South Taranaki Bight is also the largest offshore natural gas and oil exploration area in New Zealand, with seven production platforms, considerable seafloor pipelines, and significant plans for expansion in the near future. Shipping traffic and seabed mining activities have been shown to impact Blue whales directly – altering their behaviour and degrading their habitat through acoustic disturbance and ship strikes. We need to gain a better understanding of how and when Blue whales forage here so that possible impacts can be avoided.”

… The study was funded by OMV NZ Limited and NIWA, and has just been published in the New Zealand Journal of Marine and Freshwater Research.

Since the study was accepted for publication, 49 additional Blue whale sightings in the South Taranaki Bight have been reported to Dr Torres, including 33 sightings by marine mammal observers during a recent seismic survey earlier this year.

Related articles

• Blue whale protection may need to increase (nzherald.co.nz)
• Facts About Blue Whales (expertscolumn.com)
• Blue whale reveals a fluke, or tail, that resembles an airplane wing (grindtv.com)
• Big-Nippled Flying Whale Monster Coming to Australia (animalnewyork.com)
• PHOTOS: Body of Fin Whale Washes Up at Seahurst Park Beach Saturday (b-townblog.com)
• Help Save Blue Whales from Deadly Ship Strikes!: Thank You – Take Action!: NRDC’s Save BioGems (ramyabdeljabbar.wordpress.com)

Fin whales, new research

This video from Norway says about itself:

Feb 7, 2013

Large numbers of killer whales, Humpback and Fin whales enjoying themselves with large quantities of herring in Andfjorden.

From Wildlife Extra:

Fin whale research poses more questions than answers

Using earthquake sensors to track endangered whales. By Hannah Hickey, University of Washington

May 2013. The Fin whale is the second-largest animal ever to live on Earth. It is also, paradoxically, one of the least understood. The animal’s huge size and global range make its movements and behaviour hard to study.

A carcass that washed up on a Seattle-area beach this spring provided a reminder that sleek Fin whales, nicknamed “greyhounds of the sea,” are vulnerable to collision when they strike fast-moving ships. Knowing their swimming behaviours could help vessels avoid the animals. Understanding where and what they eat could also help support the Fin whale’s slowly rebounding populations (As would Iceland stopping their Fin whale hunt. Ed.).

Fin whales sound like earthquakes

University of Washington oceanographers are addressing such questions using a growing number of seafloor seismometers, devices that record vibrations. A series of three papers published this winter in the Journal of the Acoustical Society of America interprets whale calls found in earthquake sensor data, an inexpensive and non-invasive way to monitor the whales. The studies are the first to match whale calls with Fine-scale swimming behaviour, providing new hints at the animals’ movement and communication patterns.

The research began a decade ago as a project to monitor tremors on the Juan de Fuca Ridge, a seismically active zone more than a mile deep off the Washington coast. That was the first time UW researchers had collected an entire year’s worth of seafloor seismic data.

“Over the winter months we recorded a lot of earthquakes, but we also had an awful lot of Fin-whale calls,” said principal investigator William Wilcock, a UW professor of oceanography. At first the Fin whale calls, which at 17 to 35 vibrations per second overlap with the seismic data, “were kind of just a nuisance,” he said.

300,000 whale calls analysed

In 2008 Wilcock got funding from the Office of Naval Research to study the previously discarded whale calls. Dax Soule, a UW doctoral student in oceanography, compared the calls recorded by eight different seismometers. Previous studies have done this for just two or three animals at a time, but the UW group automated the work to analyse more than 300,000 whale calls.

The method is similar to how a smartphone’s GPS measures a person’s location by comparing paths to different satellites. Researchers looked at the Fin whale’s call at the eight seismometers to calculate a position. That technique let them follow the animal’s path through the instrument grid and within 10 miles of its boundaries.

154 Fin whales tracked – Some odd patterns

Soule created 154 individual Fin whale paths and discovered three categories of vocalizing whales that swam south in winter and early spring of 2003. He also found a category of rogue whales that travelled north in the early fall, moving faster than the other groups while emitting a slightly higher-pitched call.

“One idea is that these are juvenile males that don’t have any reason to head south for the breeding season,” Soule said. “We can’t say for sure because so little is known about Fin whales. To give you an idea, people don’t even know how or why they make their sound.”

Fin whale calls – They don’t sing

The Fin whale’s call is not melodic, but that’s a plus for this approach. The second-long chirp emitted roughly every 25 seconds is consistently loud and at the lower threshold of human hearing, so within range of earthquake monitoring instruments. These loud, repetitive bleeps are ideally suited for computer analysis.

As loud as a jet

Michelle Weirathmueller, a UW doctoral student in oceanography, used Soule’s triangulations to determine the loudness of the call. She found the Fin whale’s call is surprisingly consistent at 190 decibels, which translates to 130 decibels in air – about as loud as a jet engine.

Knowing the consistent amplitude of the Fin whale’s song will help Weirathmueller track whales with more widely spaced seismometer networks, in which a call is recorded by only one instrument at a time. Those include the Neptune Canada project, the U.S. cabled observatory component of the Ocean Observatories Initiative, and the huge 70-seismometer Cascadia Initiative array that’s begun to detect tremors off the Pacific Northwest coast.

“We’d like to know where the Fin whales are at any given time and how their presence might be linked to food availability, ocean conditions and seafloor geology,” Weirathmueller said. “This is an incredibly rich dataset that can start to pull together the information we need to link the Fin whales with their deep-ocean environments.”

Related articles

• Scientists Use Earthquake Sensors to Track Movements of Fin Whales (hngn.com)
• Whales to be Tracked Globally With Earthquake Sensor Arrays (latinospost.com)
• Using earthquake sensors to track endangered whales (eurekalert.org)
• Scientists Track Endangered Fin Whales with Earthquake Sensors (scienceworldreport.com)
• Tracking Fin Whales With Seismometers Provides ‘Incredibly Rich’ Data (natureworldnews.com)
• Iceland to resume commercial fin whale hunt (radionz.co.nz)

Gray whale seen off Namibia

From Wildlife Extra:

Gray whale spotted off Namibia

A rare and mysterious visitor in Walvis Bay

Courtesy of John Paterson; Albatross Task Force and Walvis Bay Strandings Network

May 2013. Gray whales, Eschrichtius robustus, range in the high Arctic (Pacific) and northern Pacific Oceans, venturing as far south as Baja California and Mexico on the west coast of America and the Korean Peninsula to breed in summer. Gray whales did occur in the North Atlantic Ocean, but [were] hunted to extinction in the 1700′s, but [were] never known to venture south of the equator. Or so we thought.

On 04 May 2013, tour boats on a dolphin cruise to Pelican Point (Namibia) saw a strange whale. Several more sightings during the following week seemed to indicate the unlikely fact that a Gray whale was visiting Walvis Bay! On Sunday 12 May a member of the Walvis Bay strandings network confirmed the reports that there was a Gray whale in the locality. This is the first known record of this species in the Southern Hemisphere. The question is now “what is the origin of this whale?”

Gray whale in the Mediterranean
In May 2010 a Gray whale was seen off Israel in the Mediterranean sea and (presumably) the same whale was seen 22 days later in Spanish waters, also in the Mediterranean. This sighting raised much speculation on the origin of the whale and the reasons for its appearance. It was suggested that the whale originated from the eastern Pacific population and was able to navigate around the north of Canada due to the reduction in size of the Arctic ice cap caused by global warming. This climatic trend would potentially allow these whales to re-colonise their historic range in the North Atlantic.

Relevant links

• Namibia Dolphin Project
• Walvis Bay Strandings Network
• Mola Mola Tours
• Albatross Task Force
• Catamaran Charters
• Namibia Nature Foundation

Different animal
The authors of that report stressed that it was difficult to draw conclusions from a single event and were only proposing likely hypotheses. Three years later a Gray whale makes its mysterious appearance in Walvis Bay. Comparison of the photographs of the Walvis Bay animal with the Mediterranean animal suggests that they are not the same individual. Is it another individual that has traversed the North West Passage? Or perhaps travelled around the southern tip of South America and across the Atlantic?

Unfortunately, we’ll never know the route it followed to get here but keen eyes on the water may tell us where it goes next, so please send your reports to the WBSN if you see this animal.

Gray whales grow up to 14 m in length and undertake the longest known migration of any mammal completing a round trip of over 30,000 km between their summer feeding grounds in the High Arctic and winter breeding area off the coast of Mexico returning to the High Arctic again. The whale seen off Israel had completed the longest known stray by any mammal. Though they are baleen whales Gray whales are unique in that they feed off the bottom of the sea floor by sucking up mud, usually through the right side of their mouths, and filter out the bottom mud dwelling amphipods on which they feed. This results in the baleen being shorter in one side of their mouths.

Namibia marine sightings
This sighting highlights the chances of seeing amazing animals in Namibia and also how important our marine environment is to sea life. Well done to the marine tour operators for locating this whale and operating in a responsible manner and not scaring the whale off. The Walvis Bay Strandings Network would like to thank the tour operators for passing on all sightings of this whale and particularly Mola Mola Tours for making space on their vessel so that we could confirm the identification and get photographs.

The Gray whale was spotted off Namibia – Photo and information courtesy of John Paterson of the Albatross Task Force.

Related articles

• Gray whale photographed off Namibia is first-ever documentation of species in Southern Hemisphere (grindtv.com)
• First Gray Whale Seen South of Equator (newser.com)
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• Grey Whale Spotted South of the Equator (education.nationalgeographic.com)
• Gray whale sighting at Golden Gardens last night (myballard.com)
• Whale Watching in the Sea of Cortez and in Laguna Magdelena and Laguna San Ignacio – July 30th at Saylor’s Restaurant (acs-sfbay.org)

Big Scottish sperm whales pod

This video is called Sperm Whales – Back From The Abyss FULL doc.

From Wildlife Extra:

Largest pod of Scottish sperm whales for nearly 20 years

14 sperm whales spotted in North Sea

April 2013. A pod of 14 sperm whales was spotted off North Berwick last week; the whales were thought to be heading towards Fife. This is the largest group ever seen in the North Sea and one of the largest pods ever seen off the UK coast – according to marine research and conservation charity Sea Watch Foundation.

Largest and longest running sightings database

Sea Watch has the largest and longest running sightings database in Europe. According to its records, other large groups in Scotland included 11 on 7 December 1994 at Sanday, Orkney; up to 17 in late November 1996 near Stornoway, Isle of Lewis; 12-14 on 14 July 1998 in the Fair Isle Channel, and a group of nine near the mouth of the River Spey, Moray Firth on 19 November 2006.

The sighting was reported to the Scottish Seabird Centre in North Berwick, an official 2013 Sea Watch Foundation National Whale and Dolphin Watch site, by microlight pilots from East of Scotland Microlights. Their photographs, taken from a height of 500ft, show that most, if not all, are immature whales, probably young males. From the Isle of May, they were last seen heading past Fife Ness and out towards the North Sea. The sperm whales had been spotted also by Scottish Natural Heritage Reserve Manager, David Pickett and others from the Isle of May in the Firth of Forth.

Sea Watch director, Dr Peter Evans, says: “There have been reports of unusually large numbers of squid – their main prey – off the Scottish coast In recent years including this winter, and this may well have attracted the group into the North Sea.

Report sightings

“We are alerting all our observers to watch for them. Ideally we are hoping that people will be able to take pictures of their tails as they dive. We will then try to match those with records of sperm whales held in the Caribbean (where they breed) and the records of those seen in the North Atlantic from Norway and the Azores to see whether any individuals have previously been recorded in these waters.”

Pictures of the tails of any of the sperm whale diving should be sent to: photo@seawatchfoundation.org.uk.

Comparisons of tail flukes of sperm whales spotted in February on the west coast of Scotland between Loch Torridon and South Rona failed to find any matches with other sperm whales seen in the North Atlantic. The following month, a sperm whale spent some days close to Oban Harbour.

Dr Evans said: “This is an exciting opportunity to observe sperm whales in the region. If anyone can get pictures of their tail flukes when they fluke-up before diving (ideally from directly behind) then we would be able to check for matches with animals elsewhere in the Atlantic and to check if they return again in subsequent years, thus helping us to build up a picture of population trends for the species in UK waters. This year we have already recorded more sperm whales in the region than ever before. Whether or not this is due to the presence of lots of squid remains to be proven, and we need to collect data over time to determine whether or not there is a longer-term trend towards more sperm whales off the UK coast.”

Sea Watch hosts National Whale and Dolphin Watch 2013 from July 27 – August 4. The watch is an opportunity for the public to help in developing a ‘snapshot’ of species around the entire UK coast. For more details of how to take part go to www.seawatchfoundation.org.uk.

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• Orcas battle sperm whales in cetacean battle royal (newscientist.com)
• Sperm whale killed by plastic (dearkitty1.wordpress.com)
• Expedition documents epic clash of titans: orcas versus sperm whales (grindtv.com)
• Photographer Captures Dramatic Battle Between Orcas and Sperm Whales (wired.com)
• Video Of Killer Whales Attacking Sperm Whales Is World First, Filmmaker Says. (natureworldnews.com)
• A whale of a time in the Forth (sykose.com)

Irish basking shark news

This video says about itself:

Jonathan Bird’s Blue World: Basking sharks and Lampreys

May 8, 2012

In 1998, Jonathan made a remarkable discovery about Basking sharks, the second largest fish on Earth. While diving with Basking sharks in the frigid waters of the Bay of Fundy, Jonathan saw parasitic lampreys on the backs of the sharks. This had never before been documented, so he returned the next year with a shark biologist and a lamprey biologist to attempt to recover living lampreys from the backs of Basking sharks. They didn’t think Jonathan could do it. Wait until you see what happens!

From Wildlife Extra:

Early flurry of Basking shark sightings off Ireland

Courtesy of the Irish Whale and Dolphin Group

April 2012. A dozen basking sharks were sighted off Slea Head in Ireland’s County Kerry on 11th April by watcher Nick Massett. This isn’t as unusual as it may seem, as almost to the day a year ago Nick also recorded 22 basking sharks off Slea Head.

Clearly the waters off the Dingle peninsula provide important early season feeding for basking sharks. A settled period of a few sunny days of warm weather should see basking shark sighting records from other inshore sites. Over the coming 2-3 months basking sharks should be visible along much of the Irish coastline, although sightings in the Irish Sea, north coast and northeast tend to be much later in the year between August-September.

On 4th April Nick observed a minimum of three sharks from Slea head, with a further two on the 5th and an impressive tally of 6 animals on 6th April.

This is good timing for the IWDG’s first Cape Clear whale (and basking shark) watching weekend on 31st May-2nd June, which will have a certain shark flavour.

Further information on basking sharks in Irish waters can be found on www.baskingshark.ie.

Read more stories about the Irish Whale and Dolphin Group here.

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• Shark liver oil: When Scots hunted big sharks (bbc.co.uk)
• Study Says 100 Million Sharks Are Killed Each Year (newsy.com)
• World body agrees to protect sharks (skynews.com.au)
• Sharks and filmmakers visit Sue Buel (newsregister.com)
• Sharks Are the New Whales (slate.com)

Mysterious Pacific whale sound

From Wildlife Extra:

The world’s loneliest and unidentified whale swims alone around the Pacific

Hertz 52 – The unknown whale

April 2013. In 1989, a team of Woods Hole Oceanographic Institution (WHOI) biologists first detected an unusual sound in the North Pacific Ocean. It had all the repetitive, low-frequency earmarks of a whale call, but at a unique frequency-52 Hertz-far higher than the normal 15-to-25-hertz range of blue or fin whales. They recorded it again in 1990 and 1991.

With the end of the Cold War, the U.S. Navy partially declassified its Sound Surveillance System (SOSUS), a hydrophone network built to monitor Soviet submarines. Using SOSUS, the WHOI team picked up the lone call of the same 52-hertz whale and have tracked it every year since, as it roamed widely through the North Pacific, from offshore California to the Aleutian Islands off Alaska.

Only call of its kind ever heard

“It is perhaps difficult to accept that if this was a whale, that there could have been only one of this kind in this large oceanic expanse, yet in spite of comprehensive, careful monitoring year-round, only one call with these characteristics has been found anywhere, and there has been only one source each season,” the scientists wrote in their study, published in Deep-Sea Research.

Malformed, deaf or a hybrid

The 52-hertz call may be due to a malformation, or the whale may be a hybrid of two species, the scientists speculated, but whatever the cause, it “has provided an unusual opportunity to document the seasonal activities of what we believe to be an individual whale.” The route the whale follows is unlike any known species, but could be described as half way between blue and fin whales.

It has also been suggested that the whale might be deaf. Dr. Kate Stafford, a researcher at the National Marine Mammal Laboratory in Seattle, said there were reasons to believe that the whale was healthy. “The fact that this individual has been capable of existing in that harsh environment for at least these 12 years indicates there is nothing wrong with it,” she said.

Of course, it sounds like a whale, but there is no proof of that. The animal, or whatever it is making the moise, has never been seen, and the time lag between when the calls are recorded and when the information is examined and released make it impossible, currently anyway, to go and find Hertz 52.

Every year 1992 – 2004, the WHOI team picked up the 52-hertz call sometime between August and December and monitored it until the whale swam out of range, always within a few weeks in January or early February. Traveling 31 to 69 kilometres per day, it was tracked over a low of 708 kilometres one season and a high of 11,062 kilometres in 2002-03.

“The usual tracking for an individual whales last hours at best,” the scientists said.

The research was conducted by Mary Ann Daher, Joseph George, David Rodriquez, and William Watkins, who pioneered the field of marine mammal acoustics with William Schevill at WHOI in the 1950s, and who died in September.

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• Wallflower (futilitycloset.com)
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• A Lonely Whale’s Unrequited Love Song (itsokaytobesmart.com)
• Does the Loneliest Whale really exist? (boingboing.net)
• What a beached whale ate, new research (dearkitty1.wordpress.com)
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What a beached whale ate, new research

This video is called Northern Bottlenose Whale Species Identification.

In 1956, a female northern bottlenose whale beached near Oudeschild village on Texel island in the Netherlands.

Recently, the contents of its intestines were investigated at Ecomare museum on Texel.

Arthur Oosterbaan of the museum investigated squid bills.

This is called A close-up video of Boreo Atlantic Armhook Squid, Gonatus fabricii in the deep waters of the Canada Basin.

Most were bills of the Boreo Atlantic armhook squid (Gonatus fabricii).

The others were Gonatus steenstrupi, a bit more southern species.

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• Pilot whale beaches in Cornwall (dearkitty1.wordpress.com)
• Scottish sperm whales new to scientists (dearkitty1.wordpress.com)
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Pilot whale beaches in Cornwall

This video is called Long-finned Pilot Whale Species Identification.

From Wildlife Extra:

Pilot whale strands in Falmouth

Whale too ill to survive

April 2013. At 11am on 15th April, British Divers Marine Life Rescue (BDMLR) received a call from the Cornwall Coastguard telling alerting them that a dolphin had stranded on the beach at Falmouth. They scrambled their marine mammal medics they arrived on the scene within half an hour to discover that the dolphin was actually a Long-finned Pilot whale.

The medics immediately started to administer first aid to the whale, and to protect the whale from the sun (which dries out and cracks its skin) the medics placed towels drenched in water over the whale.

BDMLR maintain a whale rescue trailer which arrived shortly after towed by BDMLR director Dave Jarvis. The whale was 4.1 metres long and probably a juvenile. The whale was also solitary which was unusual as they live in large pods – This was a worry to the rescue team as Long-finned pilot whales are known to strand en masse – As happened in Scotland last September – But as yet there is no sign of any more whales in the area.

Poor condition

On assessment the body condition was found to be poor and a decision was taken to euthanize the whale. BDMLR main aim is to prevent suffering and to return a whale to the sea that is not in a condition to survive would simply increase the suffering of the whale.

Dave Jarvis said “It’s always a hard decision to end a life but in this case I feel it was justified.”

A full post mortem will be carried out on the whale to determine the reason it came ashore.

Long-finned pilot whales

Long-finned pilot whales occur in the North Atlantic and across the southern hemisphere at lower latitudes. Adults can grow up to 7 metres long and can weigh up to 3 tonnes.

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• Beached Whale: Rescuers In Race Against Time (news.sky.com)
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Porpoise follows sailing boat, video

This video shows a harbour porpoise in Grevelingen lake in the Netherlands, swimming along a sailing boat.

The video is by A. Kamperman.

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Great white sharks scavenging on dead whales

This video says about itself:

Jonathan Bird’s Blue World: Great White Sharks

May 8, 2012

Perhaps best known for its role as the antagonist in the film Jaws, the Great White shark is probably the world’s most feared animal, and easily the most fearsome of the sharks. Jonathan travels to Mexico to meet a Great White up close and personal. Nothing can prepare him for the sheer size and strength of a fully grown Great White shark! He learns how white sharks are being studied and how they react to both people and sea lions.

From the University of Miami in the USA:

Great white sharks

New eco study looks at Great white shark behavior

MIAMI –April 9, 2013 – Many terrestrial animals are frequently observed scavenging on other animals– whether it is a hyena stealing a lion kill in the Serengeti or a buzzard swooping down on a dead animal. However, documenting this sort of activity in the oceans is especially difficult, and often overlooked in marine food web studies.

In a new study published in PLOS ONE titled, “White sharks (Carcharodon carcharias) scavenging on whales and its potential role in further shaping the ecology of an apex predator,” Captain Chris Fallows from Apex Expeditions collaborated with University of Miami (UM) scientists Dr. Neil Hammerschlag and Austin Gallagher, to explore the behaviors of Great white sharks scavenging on dead whales in South Africa. The team documented as many as 40 different sharks scavenging on a carcass over the course of a single day, revealing unique social interactions among sharks.

The study summarized observations based on four scavenging events opportunistically observed over a 10 year period. In each multi-day observation, the team recorded daily evidence of social, aggregative and feeding behaviors observed in the waters off South Africa. They suggest that although the occurrence of coming upon a whale carcass may be sporadic, the shark populations are likely prepared to scavenge on them, and may even rely on their scavenging activities to supplement their regular feeding activities.

“Although rarely seen, we suspect that as white sharks mature, scavenging on whales becomes more prevalent and significant to these species than previously thought,” said Hammerschlag, who is director of the R.J. Dunlap Marine Conservation Program at UM.

The team found that sharks showed a clear preference for scavenging on the blubber, probably because these high calorie meals can sustain the sharks for longer periods of time. Interestingly, though, the study also found that sharks showed an initial preference for feeding on the whale’s fluke before moving on to feed on the rest of the carcass. The team also found that while scavenging on whales, they ceased hunting and feeding on seals, one of their primary natural prey.

“While scavenging on the whale, the sharks clearly showed a size-based pecking order,” said Fallows. “The biggest sharks came right in, targeting areas of highest blubber content, while smaller sharks fed on areas with less blubber or kept their distance from the whale, mostly scavenging on pieces of blubber that drifted away from the carcass.”

The paper reveals how the social and size structure of sharks at the carcass appeared to be influenced by environmental patterns. “The cues, such as the oils, emanating from this pulse of food are likely attracting much larger sharks over 4.5 meters from long distances to scavenge,” said Gallagher. “These data provide some credence to the hypothesis that large white sharks may be swimming known ocean corridors looking for dead, dying, or vulnerable whales.”

“By attracting many large white sharks together to scavenge, we suspect that the appearance of a whale carcass can play a role in shaping the behaviors, movements, and the ecosystem impacts of white sharks” said Hammerschlag. “These patterns may shed some light into the ecology of this often studied – yet still highly enigmatic – marine predator.”

Sharks dive deeper during a full moon: here.

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