Orca ‘apocalypse’: half of killer whales doomed to die from pollution

September 27, 2018

At least half of the world’s killer whale populations are doomed to extinction due to toxic and persistent pollution of the oceans, according to a major new study.

Although the poisonous chemicals, PCBs, have been banned for decades, they are still leaking into the seas. They become concentrated up the food chain; as a result, killer whales, the top predators, are the most contaminated animals on the planet. Worse, their fat-rich milk passes on very high doses to their newborn calves.

PCB concentrations found in killer whales can be 100 times safe levels and severely damage reproductive organs, cause cancer and damage the immune system. The new research analysed the prospects for killer whale populations over the next century and found those offshore from industrialised nations could vanish as soon as 30-50 years.

Among those most at risk are the UK’s last pod, where a recent death revealed one of the highest PCB levels ever recorded. Others off Gibraltar, Japan and Brazil and in the north-east Pacific are also in great danger. Killer whales are one of the most widespread mammals on earth but have already been lost in the North Sea, around Spain and many other places.

“It is like a killer whale apocalypse,” said Paul Jepson at the Zoological Society of London, part of the international research team behind the new study. “Even in a pristine condition they are very slow to reproduce.” Healthy killer whales take 20 years to reach peak sexual maturity and 18 months to gestate a calf.

PCBs were used around the world since the 1930s in electrical components, plastics and paints but their toxicity has been known for 50 years. They were banned by nations in the 1970s and 1980s but 80% of the 1m tonnes produced have yet to be destroyed and are still leaking into the seas from landfills and other sources.

The international Stockholm Convention on Persistent Organic Pollutants came into force in 2004 to tackle the issue, but Jepson said the clean-up is way behind schedule. “I think the Stockholm Convention is failing,” he said. “The only area where I am optimistic is the US. They alone produced 50% of all PCBs, but they have been getting PCB levels down consistently for decades. All we have done in Europe is ban them and then hope they go away.”

The researchers said PCBs are just one pollutant found in killer whales, with “a long list of additional known and as yet unmeasured contaminants present”. Further problems for killer whales include the loss of key prey species such as tuna and sharks to overfishing and also growing underwater noise pollution.

The new research, published in the journal Science, examined PCB contamination in 351 killer whales, the largest analysis yet. The scientists then took existing data on how PCBs affect calf survival and immune systems in whales and used this to model how populations will fare in the future. “Populations of Japan, Brazil, Northeast Pacific, Strait of Gibraltar, and the United Kingdom are all tending toward complete collapse,” they concluded.

Lucy Babey, deputy director at conservation group Orca, said: “Our abysmal failures to control chemical pollution ending up in our oceans has caused a killer whale catastrophe on an epic scale. It is essential that requirements to dispose safely of PCBs under the Stockholm Convention are made legally binding at the next meeting in May 2019 to help stop this scandal.” Scientists have previously found “extraordinary” levels of toxic pollution even in the 10km-deep Mariana trench in the Pacific Ocean.

“This new study is a global red alert on the state of our oceans,” said Jennifer Lonsdale, chair of the Wildlife and Countryside Link’s whales group. “If the UK government wants its [proposed] Environment Act to be world-leading, it must set ambitious targets on PCB disposal and protect against further chemical pollution of our waters.”

The research shows that killer whale populations in the high north, off Norway, Iceland, Canada and the Faroes, are far less contaminated due to their distance from major PCB sources. ”The only thing that gives me hope about killer whales in the longer term is, yes, we are going to lose populations all over the industrialised areas, but there are populations that are doing reasonably well in the Arctic,” said Jepson.

If a global clean-up, which would take decades, can be achieved, these populations could eventually repopulate empty regions, he said, noting that killer whales are very intelligent, have strong family bonds and hunt in packs. “It is an incredibly adaptive species – they have been able to [live] from the Arctic to the Antarctic and everywhere in between.”

He praised the billion-dollar “superfund” clean-ups in the US, such as in the Hudson River and Puget Sound, where the polluter has paid most of the costs: “The US is going way beyond the Stockholm Convention because they know how toxic PCBs are.”

Source: The Guardian.com

Advertisements

Rare footage captures the gruesome moment two killer whales attack and disembowel a dolphin off the coast of Namibia

March 19, 2018

  • A ravaged dolphin carcass washed up on a beach near Pelican Point, Namibia
  • Experts captured rare footage of a whale attacking a dolphin just one day earlier 
  • Incredible footage shows a Heaviside’s dolphin being flipped out of the water
  • Scientists believe the remains belong to the dolphin they caught on camera

Rare footage has captured the horrifying moment a dolphin was ravaged by killer whales off the coast of Africa. 

The gruesome attack was captured by scientists who recorded the moment the dolphin was tossed out of the water and into the jaws of one of the huge mammals.

Its ravaged carcass was washed up on a beach days later after being torn apart by two of the beasts.

Images of the remains of the Heaviside’s dolphin show the body after it was disembowelled and shredded of its blubber.

Researcher Dr Simon Elwen said while such attacks were not uncommon, in 20 years of research on marine mammals, he had never seen a carcass so severely ravaged. 

The body was found washed ashore on a beach near Pelican Point, Namibia, earlier this month.

Authorities contacted a marine biology team to identify the creature but, by the time they reached the scene, the body had been swept back into the ocean.

In a twist of fate, the same scientists had captured the start of the feeding frenzy footage just one day earlier.

The research team, known as Namibian Dolphin Project (NDP), was looking at the impact of an oil spill when the distinct dorsal fin of a killer whale broke the surface of the water.

In a flurry of activity, two killer whales can be seen in the clip hunting the unfortunate dolphin.

Dr Elwen, who is the NDP Director, said: ‘The heavily mutilated, freshly dead carcass was reported on a nearby beach through the local strandings network.

The NDP responded to the call but the carcass could not be found and is thought to have washed out to sea.’

Dr Elwen said in 20 years of research on marine mammals, he had never seen a carcass so severely ravaged. 

Whilst the team can not study the remains, they believe the footage and the condition of the carcass indicate that the killer whales were responsible.

‘I have only ever seen animals “peeled” of their blubber and with their organs pulled out being caused by killer whales,’ Dr Elwen added.

‘So there’s every indication the carcass belonged to the adult Heaviside’s dolphin attacked in our footage from the day before.’ 

Killer whales hunt in packs, attacking their prey from multiple directions to keep them from escaping.

In this attack, the whales hunted as a pair, with one attacking and the other orca circling ominously.

The rare sighting was the first time the group had witnessed killer whales in those waters in 600 trips.

Dr Elwen said: ‘This is a once-in-a-lifetime event with highly valuable data, so the team mobilised immediately.’

‘After about an hour they spotted a very quick rush at the surface back and forth. The larger killer whale lifted his body out of the water and revealed an adult sized Heaviside’s dolphin in his mouth.

‘We could see that the Heaviside’s dolphin was bleeding but there was no further struggle and the killer whales dove underwater with their prey.’

Source: Daily Mail.co.uk

3 Great Whites Washed Up Dead in South Africa with Missing Livers and a Missing Heart

December 12, 2017

In early May, great white sharks began washing up dead on beaches in South Africa. All of them had massive tears beneath one of their pectoral fins, and all of them were missing their livers. Researchers now believe it’s a clear sign of orca predation–an odd thing, considering that orcas aren’t exactly common in the area.

“From a scientific perspective in South Africa, it’s absolutely unprecedented,” said Alison Towner, a white shark biologist at the Dyer Island Conservation Trust in Gansbaai, South Africa. “I’ve seen some incredible things working with the Dyer Island Conservation Trust, but one thing I never ever expected to see was predation pressure from killer whales. We had never even seen an orca here prior to 2011.”

In the days prior to the dead sharks, scientists at Marine Dynamics saw two orcas off the southwestern coast of South Africa.  Soon after, three dead sharks washed up within days of each other, leaving researchers baffled. When they performed the autopsies, though, it quickly became clear that killers whales were responsible. All the sharks were missing their livers, and one was missing its heart, which as odd as it sounds, is something that orcas do.

Killers whales have been known to hunt great whites, but only on very rare occasions. They normally eat seals, other whales, and some smaller sharks. Towner, though, thinks that now that these ones have learned to kill great whites, they’ll keep on doing it. “Now they have learned how to kill white sharks,” she said, “it’s probably not going to stop anytime soon.”

While it’s not known exactly how orcas might kill a great white, there are a few theories. When a shark is upside down, it goes into a comatose-like state called tonic immobility. It’s possible that an orca might flip the shark over, then drag it backwards until it drowns. In the South African cases, the orcas then removed the livers, the largest and most nutrient-rich organs in a great white.

Experts suspect that the great whites that washed up in South Africa are just a fraction of the ones that may have been killed. If that’s the case, the others likely sank to the seafloor.

This is only the third time that orcas have been recorded hunting great whites, once off California and once of Australia. Scientists are more than a little worried about this new threat to the shark population in the area.

“Sharks face many threats in Southern Africa” Towner explained. “Fisheries, bather protection nets, poaching, pollutants, coastal development, global warming impacts. Now they have predation pressure from another predator, the odds are just not stacked up in their favor.”

To watch the VIDEO visit the source at The Inertia.com

UPDATE: SA mystery of the killer orcas continues as 4th great white found dead

June 26, 2017

Cape Town – The mysterious orca predation of endangered great white sharks is on again, according Marine Dynamics 

On Saturday, 24 June the shark Cage diving company confirmed that another great white shark was found dead with wounds indicative of an orca attack.

This comes after a suspected orca whale killing spree of great white sharks gripped the coast of South Africa in May 2017, resulting in the first ever dissection of a white shark following an attack of this nature.

Biologist Alison Towner has confirmed that another 4.2m male great white shark was found dead with the same injuries as previous sharks – livers neatly removed but little else eaten – indicating orca predation. 

Towner told Traveller24 that the attacks are largely being attributed to a pair of orca, nicknamed port and starboard due to the slanting of their dorsal fins, also see at Dangerpoint over the weekend. 

She says the two orcas are known to be shark hunters, as they have apparently killed other shark in species in the area.

Towner says these two animals were also spotted in the bay, when the previous attacks took place. 

But what’s most concerning about this rather unusual behaviour is the lack of Great White Shark activity – with Marine Dynamics posting to its blog about little to no sightings in the area.

As a result there are is no cage diving or boating activity. 

Towner says that winter in South Africa is prime hunting season in SA, when you would typically expect to see the highest number of great white sharks – but unfortunately that’s not the case as the is no white shark activity around the island.  

Great White sharks would instinctively avoid the area, because of the orca threat, says Towner who says a positive is that both species are highly transient and migratory and “don’t specifically live in this area and would just be moving through”.

But at present, the long term patterns or effects of the orca predation remain unclear. 

“It is worrying and we don’t know what the long term impact of these attacks will be,” says Towner.   

Timeline of great white killings

Following the dissections in May, the Department of Environmental Affairs (DEA), confirmed that orca whales were responsible for three shark killings, and that they were targeting the large nutrient-rich livers of the sharks. Various small pods of orcas were also spotted around Gansbaai during the time the killings occurred.

In all three previous cases Townsend confirmed the livers of the sharks in all three cases were neatly removed, with almost surgical precision, but little else was eaten. Even the hearts of the two of the sharks were left intact. 

“We have never seen anything like this,” said Towner at the time, who contributed to the dissection of the sharks. In all three cases, “there was a large gaping hole between her pectoral fins where they were torn apart to reveal her body cavity … and that their large livers were completely missing. This information, combined with the recent sightings of orca and disappearance of white sharks in the area, provides convincing evidence that the orcas are responsible for the shark’s death.”

“This is an extremely rare occurrence,” she said in an email with Traveller24, “This is also the first time worldwide the carcass of a white shark was recovered post orca predation, let alone three carcasses within one week!”

The first dead shark—a massive one-ton great white—washed up on the shore in Gansbaai on 3 May. The first people at the scene were initially perplexed as to how such a large shark could have died, and it wasn’t until a dissection, authorised by the Department of Environmental Affairs (DEA) in conjunction with the White Shark Research Group, Marine Dynamics and the Dyer Island Conservation Trust, revealed that the shark’s liver was missing.

The next day, another 3,5 meter shark washed up on the shore at Franskraal beach, and a later dissection revealed that this one’s liver was also missing.  “This is a difficult yet fascinating time,” said Towner on the Marine Dynamics blog. “It is something rarely documented in marine top predator behaviour in South Africa,”

On 7 May, a third dead shark washed up, this time in Struisbaai, matching the injuries of the previous two specimens, and cementing the suspicion that these were not just random isolated incidents. “Obviously this is a very sad time for us all,” said Towner, who was on hand to assist again. “Nature can be so cruel and the dexterity these enormous animals are capable of is mind blowing, almost surgical precision as they remove the liver of the white sharks and dump their carcass.”

How and Why are Orcas targeting Great White Sharks?

Known as the “Wolves of the Sea”, orcas are the true apex predators of the ocean, and the only known predator of the great white shark. 

They are extremely intelligent, specialised hunters, feeding above sharks on the overall oceanic food chain. They hunt in organised social groups, using echo-location, strategy, and teamwork to kill their prey, which can be anything in the ocean, from seals, to dolphins, dugongs, otters, turtles, birds, squid, and sometimes even land mammals.

According to the DEA statement, the orcas were targeting the squalene rich livers that assists sharks with their buoyancy. This substance is also highly nutritious pound for pound, compared with the muscle tissue. Although this type of selective feeding on livers is extremely rare in orca whales, seals have been known to predate sea birds where they often remove and consume only the stomach/abdominal content and not the rest of the carcass.   

Orcas are also suspected to be responsible for a decline in Cape Town’s cow shark population, and have been known to predate these sharks. Alison Kock, a Marine Scientist for Shark Spotters, reported recovering several cow shark carcasses in a similar condition with their livers removed, in False Bay subsequent to a series of orca sightings.

How the orcas are able to extract the livers so neatly from the sharks is a bit of a mystery. But footage off the coast of California showed team-work between the orcas pushing a white shark to the surface, belly up, biting into its flesh, before letting buoyant, oil-rich liver as it float out of the cavity. 

What does this mean for Great White Sharks in South Africa?

Orca whales are widely distributed in the ocean, extending from the Arctic to the Antarctic, into the tropics, and are present in both coastal and oceanic waters.

According to figures from the DEA, orca whales are fairly common along the coast of South Africa, and some 785 sightings have been recorded ranging from the Western Cape all the way to Northern KwaZulu-Natal. “The sightings of Orca pods appears to be increasing in South Africa,” they said in a recent statement, but these sightings could also be attributed to more people on the ocean with eyes on the water.

The incidents have already affected the number of great white sightings, as the sharks leave the bay to avoid the orcas. The killings are a blow to the already struggling population of great white sharks in South Africa, a local population which some scientists say is facing extinction.

The DEA, along with various shark scientists and marine mammalogists, is currently collating all the scientific information about the incidents, and they are urging the public to be aware that this is a natural phenomenon, and might have to do with changes in seasons or temperatures and prey regimes of the orcas.

Source: Traveller24.com

Killer whale blamed for death of 2 giant white sharks washed ashore with liver missing

– Two gigantic white sharks found dead ashore, one without liver

– Experts believe the two sharks were murdered by orca, a killer whale

– Marine biologists still examining one of the bodies for more information

Two gigantic white sharks were recently found lying motionless on the shores of Frankskraal near Gansbaai. The first shark was a female measuring 5 meters long and reportedly the largest to be washed ashore in Gansbaai since 2012. The mammal was found with its liver missing. According to Allison Towner, marine biologist at the Dyer Island Conservation Trust, the female shark was slaughtered by orca, a deadly killer whale that is known to eat sharks’ liver. 

“It is quite conclusive given the fact that a liver is missing that it could well be contributed to orca. They are known to specialise on very sharp species for particularity the liver, which is a very oily organ and very nutrient dense,” says Towner. The second shark, a male measuring 3.4 metres and with huge chunks of its body missing, was found on Franskraal beach. 

Towner and Dr Malcolm Smale are reportedly conducting dissection at International Marine Volunteers and are expected to announce their findings soon.

“This specimen is in a more degraded state and cannot be frozen. We will notify further information just bear with us during this extraordinary time,” says Towner. Previously recorded behaviours seem to suggest that the sharks were all killed by orca. 

Source: Tuko.co.ke

Mysterious great white shark death off South Africa; were orcas involved?

February 9, 2017

“There will no doubt be speculation that Orcinus orca is responsible for this mortality as only yesterday we documented two male orca in the area.”

A dead great white shark was discovered Thursday off Pearly Beach, South Africa, and there’s speculation that orcas might have killed the shark.

The carcass of a juvenile female white shark was retrieved by members of the Dyer Island Conservation Trust. There were no signs of physical trauma, but there were peculiar markings on the shark.

“There will no doubt be speculation that Orcinus orca is responsible for this mortality as only yesterday we documented two male orca in the area,” Dyer Island Conservation Trust stated on its Facebook page. “[But] the fact is we cannot confirm this, it could also just be a coincidence.”

It’s hoped than an autopsy will reveal the cause of death.

Orcas, or killer whales, rarely interact physically with great white sharks, but it’s not unprecedented.

In 1997 off San Francisco, whale watchers witnessed an adult female orca killing a juvenile white shark. The orca was photographed with the shark in its mouth.

In 2015 off South Australia, a family group of orcas was involved in the killing of a white shark popular among cage divers.

In some areas, orcas commonly prey on other types of sharks.

RELATED: Great white sharks attack fishing boat during harrowing encounter off LA

Last December off Monterey, Calif., a pod of offshore killer whales passed around a large sevengill shark that it had killed. That was captured via drone-cam.

In New Zealand, orcas commonly prey on smaller sharks.

Ingrid Visser, who has studied killer whales for nearly 20 years, told the Telegraph that orcas use a specialized technique to stun their prey: “The orca will use its tail to drive the shark to the surface. They don’t even touch it. Using an up-thrust of its tail it creates a vortex which pushes the shark up on the current they create with their movements.

“Once the shark is at the surface, the killer whale pivots and lifts its tail out of the water and comes down on top of it like a karate chop.”

Source: Adventure Sports Network