Male killer whales hunt more than females

February 5, 2019, The Company of Biologists

 It's hard to tell just how imperilled killer whales are. With several different forms—some of which may even be different species—it's unclear which are at serious risk and which are less vulnerable. But one group is definitely in jeopardy. 'The southern resident killer whale population was listed as endangered in the United States in 2005', says Jennifer Tennessen from the National Oceanic and Atmospheric Administration (NOAA), USA and the decline of Chinook salmon in the Pacific Northwest—which are consumed by the population of ~75 whales—is believed to be one of the causes. While shipping also poses a risk to the animals, NOAA has been monitoring them for a decade and one of the scientists' main goals was to estimate how much fish the charismatic whales capture. But, with the majority of pursuits occurring beneath the waves, Tennessen and her colleagues needed to develop a technique based on the animals' manoeuvres that would allow them to identify when the mammals were successful. They publish their discovery that killer whale hunts are not always successful and that male killer whales hunt more than females in Journal of Experimental Biology.

Heading into the Salish Sea, between Vancouver Island, British Columbia and Washington State, Tennessen and her colleagues—Marla Holt, Candice Emmons, Brad Hanson, Jeff Hogan and Deborah Giles—attached tags to 21 whales to record their sounds and underwater movements. Then the team followed the animals, noting where they surfaced and what they were up to, in addition to retrieving the remains of any meals. 'Fieldwork is one of the most exciting yet simultaneously challenging aspects of the research', says Tennessen, describing how she and her colleagues tracked the animals from small inflatable boats in all conditions.

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Are sharks being attacked by killer whales off Cape Town's coast?

February 4, 2019 by Alison Kock And Tamlyn Engelbrecht, The Conversation

Large, predatory sharks occupy the top of ocean food chains, where they play important roles in maintaining diverse and healthy ecosystems. The loss of these predators can therefore have significant impacts on ecosystems.

For a long time broadnose sevengill sharks have occupied the apex of the food chain alongside the more famous great white sharks in False Bay on the southern tip of South Africa. Both species feed on seals, dolphins, other sharks and fish.

However, the structure of the False Bay food chain began to change significantly in 2015 with the appearance of a "new" predator, shark-eating killer whales.

The change was noted with the discovery of several dead sevengill sharks by scuba divers from a popular dive site inside the Table Mountain National Park marine protected area. This site was home to an exceptionally large group of sevengill sharks. Divers could dive with up to 70 sharks on a single hour-long dive – no other place in the world had this many broadnose sevengill sharks in one place.

Initially, the cause of death remained a mystery because no dead sharks were recovered for examination. Initially fingers were pointed to humans, great white sharks or killer whales. It was only months later following the discovery of more dead sharks and examination of the carcasses by scientists that the fingers pointed straight at killer whales.

With this information in hand we set about reviewing the literature on killer whale behaviour, dietary specialisation, and population delineation globally and locally. Based on the review we hypothesised that the attacks on broadnose sevengill sharks in False Bay were possibly indicative of the arrival of a different sub‐group – or ecotype – of killer whale in the bay that feeds on sharks.

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New orca calf seen among Puget Sound's critically endangered killer whales

January 14, 2019 by Lynda V. Mapes

A new calf has been born to the critically endangered southern resident killer whales, researchers confirmed.

The calf was born to L77, said Ken Balcomb, founding director of the Center for Whale Research. He confirmed the birth in a text to The Seattle Times Friday. He estimated the calf is several weeks old.

Center staff first saw the calf Friday morning at the eastern end of the Strait of Juan de Fuca.

"It's great news," Balcomb said, adding the calf looks healthy.

It is the first known birth to the southern residents since Tahlequah, or J35, gave birth to a calf in July that lived only a half-hour.

Tahlequah drew worldwide attention when she carried the dead infant for 17 days and more than 1,000 miles, refusing to let it go.

Any birth in the southern resident population is big news because the orcas that frequent Puget Sound in the J, K and L pods are critically endangered. There are only 74 left, with three whales lost last year.

The center also was observing K25 Friday, a southern resident whale known to be in poor body condition. If conditions allow, the center is attempting to get an update on that whale's status.

K25 is doing poorly after the death of his mother K13 in 2017. Mother orcas preferentially feed their sons and K25 has been getting thinner and thinner—so thin that Balcomb has said he is concerned he may not last the summer.

J17, Tahlequah's mother, is also so thin as to cause similar concern.

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Killer whales share personality traits with humans, chimpanzees

Complex social interactions may require certain personality traits

Date:  November 15, 2018

Source:  American Psychological Association

Killer whales display personality traits similar to those of humans and chimpanzees, such as playfulness, cheerfulness and affection, according to new research published by the American Psychological Association.

Researchers in Spain analyzed the personality traits of 24 captive killer whales (Orcinus orca) at SeaWorld Orlando, SeaWorld San Diego and the Loro Parque zoo in Tenerife, Spain, which operates its killer whale program in partnership with SeaWorld. Six of the killer whales were caught in the wild while the remainder were born in captivity.

Trainers and other staff who worked closely with the killer whales completed surveys ranking each animal on a list of 38 personality traits, including playfulness, independence, stubbornness, bravery, sensitivity and protectiveness. Those traits were analyzed and compared with previous studies of the same personality traits for chimpanzees and humans. The research was published online in the Journal of Comparative Psychology.

"This is the first study to examine the personality traits of killer whales and how they relate to us and other primates," said lead researcher Yulán Úbeda, a doctoral student in psychology at the University of Girona in Spain. "These similar personality traits may have developed because they were necessary to form complex social interactions in tightly knit groups that we see in killer whales, humans and other primates."

The study used a common personality measure called the five-factor model, which assesses five personality dimensions, including extraversion, agreeableness, conscientiousness, dominance and carefulness. The model, which was developed in the 1930s, describes personality traits using a combination of single adjectives or descriptive phrases.

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PCB pollution threatens to wipe out killer whales

September 27, 2018

Source: Aarhus University

More than forty years after the first initiatives were taken to ban the use of PCBs, the chemical pollutants remain a deadly threat to animals at the top of the food chain. A new study, just published in the journal Science, shows that the current concentrations of PCBs can lead to the disappearance of half of the world's populations of killer whales from the most heavily contaminated areas within a period of just 30-50 years.

Killer whales (Orcinus orca) form the last link in a long food chain and are among the mammals with the highest level of PCBs (polychlorinated biphenyls) in their tissue. Researchers have measured values as high as 1300 milligrams per kilo in the fatty tissue (blubber) of killer whales. For comparison, a large number of studies show that animals with PCB levels as low as 50 milligrams per kilo of tissue may show signs of infertility and severe impacts on the immune system.

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Killer whale genetics raise inbreeding questions

Endangered orca population in Washington acts genetically smaller than it really is

Date:  April 24, 2018

Source:  NOAA Fisheries West Coast Region

A new genetic analysis of Southern Resident killer whales found that two male whales fathered more than half of the calves born since 1990 that scientists have samples from, a sign of inbreeding in the small killer whale population that frequents Washington's Salish Sea and Puget Sound.

Only about 26 of the 76 endangered whales in the Southern Resident population are currently breeding, according to the analysis published this week in Animal Conservation. The limited number of breeding whales reduces the effective size of the population, leaving it less resilient to change and possibly compromising the survival of individual animals, said lead author Michael Ford, a conservation biologist at NOAA Fisheries Northwest Fisheries Science Center in Seattle.

"The effective size of this population is really small," he said. "It's acting like a population of only 20-30 individuals."

Authors of the research also include scientists from the North Gulf Oceanic Society and Center for Whale Research. While the new paper builds on earlier genetic studies, it also raises new questions about whether inbreeding may be contributing to the population's struggles. Southern Resident numbers have fallen to their lowest point in 30 years.

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Killer whales seen in river Clyde

Pod of orcas spotted between Dunoon and Gourock, thought to be hunting seals or porpoises

Matthew Taylor

Sun 22 Apr 2018 14.32 BSTLast modified on Mon 23 Apr 2018 00.55 BST

A pod of killer whales has been spotted in the river Clyde apparently hunting seals or porpoises.

Images and videos have been posted on social media over the weekend of about half a dozen killer whales, or orcas, between Dunoon and Gourock.

Lindsay Moss was on a Western Ferries service on Saturday when they made an appearance. Her footage shows three orcas, including what appears to be a youngster, rising to the surface before disappearing again.

Orcas are sociable animals that travel in groups of up to 50. Although they are frequently seen near Arran in the Firth of Clyde, they have not been regular visitors to the upper Clyde for many years, experts say.

It is thought they were attracted to the area due to its abundance of food – porpoises and seals.

In the UK, killer whales are seen most regularly around the Shetland and Orkney islands.

Source  

'Environmental DNA' used to identify killer whales in Puget Sound

Date:  April 23, 2018

Source:  Oregon State University

Summary:

When endangered killer whales swim through the sheltered waters of Puget Sound, they leave behind traces of "environmental DNA" that researchers can detect as much as two hours later, a new study has found.

The findings, published today in the journal Frontiers, are surprising and significant. They not only provide a new non-invasive way to study whales, they may help scientists locate cetacean species that are known but have rarely been detected -- including certain beaked whales.

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Nearly 50 dolphins die as 61 wash up on Argentinian beach ‘after being driven to the shore by killer whales’

Sixty-one short-beaked common dolphins found washed up in Puerto Madryn

According to authorities, 49 died on the coast of a Patagonian national park

Secretary of Protected Areas Nestor Garcia noted a killer whale increase nearby

WARNING: GRAPHIC CONTENT 

By Iain Burns For Mailonline

PUBLISHED: 11:03, 26 March 2018 | UPDATED: 11:25, 26 March 2018

More than 60 dolphins have been found stranded on a popular beach resort - and experts have said killer whales could be responsible.

Sixty-one short-beaked common dolphins were found washed up in Puerto Madryn, an Argentinian city in northern Patagonia.

According to local authorities, 49 of them died on the coast of the El Doradillo Protected Natural Area while 12 were returned to the sea alive.

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A last refuge for Europe's blighted killer whales

3 November 2017

Europe's killer whales wowed in the BBC's Blue Planet II series but these animals face extinction. Chris Gibson travelled to the small Norwegian island of Kvaløya where the orcas retain a strong foothold. But for how much longer?

It was one of those television moments. The sight of killer whales herding shoals of herring into tighter and tighter balls to trap the prey near the surface of the water.

The killer whales work as a pack of skilful hunters before deploying their secret weapon - tail-slapping the fish so hard they are either dazed or die.

The story behind those shots is even more remarkable.

They were filmed in the majestic Norwegian fjords. These long, narrow inlets are now among the few places in Europe you can see a pod of killer whales.

Across Europe, these cetaceans are declining rapidly.

In the Mediterranean and the North Sea, they have vanished.

Elsewhere, there are now only eight killer whales in the NW Scotland-Ireland population, and only 36 left in the Strait of Gibraltar population.

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Weak social ties a killer for male whales

Date:  October 24, 2017

Source:  University of Exeter

Male killer whales are more likely to die if they are not at the centre of their social group, new research suggests.

Scientists from the universities of Exeter and York (UK) and the Center for Whale Research (USA) found the most socially isolated males were three times more likely to die in any given year than those in the "most central social positions."

The effect was much stronger in years where food was scarce, and it did not affect females -- possibly because males are larger and need more support from the group to get enough food.

The findings come from research on Southern Resident killer whales, a critically endangered population in the Pacific Ocean that -- following a recent death -- numbers just 76.

"This research highlights the importance of social bonds to male killer whales, and shows that males that are less socially connected are more likely to die when times are hard," said lead author Dr Samuel Ellis, of the University of Exeter.

"Killer whales are highly cooperative, and males at the centre of a social group are likely to have better access to social information and food-sharing opportunities."

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Orca Calf Dies at SeaWorld: Why Killer Whales Get Sick in Captivity

By Tracy Staedter, Live Science Contributor | July 27, 2017 06:15pm ET

A 3-month-old orca calf named Kyara died this past weekend, possibly from pneumonia, at SeaWorld San Antonio. This isn't the first occasion of a killer whale dying in captivity.

Dozens of other captive killer whales, including the SeaWorld orca named Tilikum, who was made famous in the documentary "Blackfish," have also died from bacterial infections.

According to SeaWorld’s press statement, Kyara's death, which is still being investigated, was not the result of living in captivity. But some experts in marine mammal research say that the living conditions contribute to disease.

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Study links at-risk orcas' failed pregnancies to scarce food

 June 29, 2017 by Phuong Le 

Endangered killer whales that frequent the inland waters of Washington state are having pregnancy problems because they cannot find enough fish to eat, according to a new study.

Researchers analyzed hormones in excrement collected at sea and found that more than two-thirds of orca pregnancies failed over a seven-year period. They linked those problems to nutritional stress brought on by a low supply of Chinook salmon, the whales' preferred diet.

"A large number of whales are conceiving, but when nutrition is poor, they don't sustain those pregnancies," said Sam Wasser, lead author of the paper and a biology professor at the University of Washington.

Southern resident killer whales along the U.S. West Coast have struggled since they were listed as endangered species in 2005. They now number just 78, down from a high of 140 decades ago. The whales face threats from a lack of food, pollution and boats.

The new study, to be published Thursday in the journal PLOS ONE, zeroes in on food supply as an important stress factor among these fish-eating whales. Unlike other killer whales that eat marine mammals, the orcas that spend the summer in Puget Sound primarily eat salmon, mostly Chinook.

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‘Unprecedented’ series of killer whale attacks filmed in California

May 1, 2017


by Chuck Bednar


A group of orcas was caught on video killing a gray whale calf last Friday – the latest fatality in what experts are calling an “unprecedented” series of attacks which were led by a group of nine related killer whales and which claimed a total of four victims over a seven-day span.

The attacks have taken place in Monterey Bay, California, and the most recent occurred on Wednesday and was filmed by Nancy Black, a marine biologist at Monterey Bay Whale Watch, according to reports published by The Guardian and the San Francisco Chronicle. The video shows the group of nine orcas separating a gray whale calf from its mother and killing it over the span of just 20 minutes. Earlier attacks had involved as many as 33 killer whales, said Black, but the same group of nine orcas, related across four generations and led by a matriarch.

Orca attacks often take hours to complete and are unsuccessful, the biologist explained. But the efficiency of Wednesday’s kill was “like a record,” she told The Guardian. “I’ve been studying them for 30 years... [and] this has really never happened before... It’s pretty unprecedented just because the same group of killer whales has been feeding on them each time.”
Delayed start to hunting season likely to blame

In a typical killer whale attack, Black told the Chronicle, the mother gray whale uses her tail in an attempt to fight off the predators, and will also roll over, belly-up with her calf on top. But in Wednesday’s attack, she said, the mother and calf were skinnier and likely weaker than typical gray whales, making them easier prey for the hunting orcas.

 
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Why do killer whales go through menopause? Mother-daughter conflict is key

Date: January 12, 2017

Source: Cell Press

Killer whales are one of only three species that are known to go through menopause, surviving long after they've stopped reproducing. Those older females play an essential role in helping their younger family members to find food and survive even in lean times. But, researchers report in Current Biology on January 12, the reason older females stop reproducing has more to do with conflict between mothers and their daughters than it does with cooperation.

According to the new evidence, when older females do reproduce alongside their daughters, their young calves are more likely to die. Under those circumstances, it's better evolutionarily speaking for older females to stop reproducing themselves and invest in helping their younger family members succeed.

"Our previous work shows how old females help, but not why they stop reproducing," says Darren Croft of the University of Exeter. "Females of many species act as leaders in late life but continue to reproduce. Our new work provides a mechanism that can explain why old females stop [reproducing] -- they lose out in reproductive competition with their daughters."

Female killer whales typically start reproducing by age 15. They stop reproducing in their 30s or 40s, but they can live to be more than 90. Earlier studies by the research team from the University of Exeter, University of York, and Center for Whale Research showed that older (post-reproductive) females play an important leadership role that benefits the family group. But the benefits of helping younger, related females alone didn't seem to be enough to fully explain why those older whales would go through menopause and stop reproducing themselves.

Earlier theoretical work by study co-authors Mike Cant, University of Exeter, and Rufus Johnstone, University of Cambridge, suggested that conflict between generations may help to explain why humans go through menopause. According to the "reproductive conflict" hypothesis, women in ancestral human social groups become more closely related to those around them with age. That trend predisposed older females to stop reproduction and invest in late-life helping. In contrast, young women are predicted to invest in competitive effort to reproduce. Cant and Johnstone later suggested that the same might be true among killer whales.

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