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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Bad breath: Study find array of bacteria when orcas exhale

March 24, 2017 by Phuong Le 
 

In this Jan. 18, 2014, file photo, a female orca leaps from the water while breaching in Puget Sound west of Seattle, as seen from a federal research vessel that has been tracking the whale. Using unique breath samples captured over four …more

When the mighty orca breaks to the surface and exhales, the whale sprays an array of bacteria and fungi in its his breath, scientists said, some good, and some bad such as salmonella.

The findings in a new study raises concerns about the potential role of infectious diseases as another major stress factor for the struggling population of endangered Puget Sound orcas.

Those orcas' breath samples revealed microbes capable of causing diseases. Some were resistant to multiple antibiotics frequently used by people and animals, suggesting human waste contaminating the marine environment, according to a study published online Friday in the journal Scientific Reports.

Scientists followed the whales as they swam in Washington state waters and waited for them to surface and exhale. The researchers on boats would swing a 25-foot long pole with several petri dishes above an orca's blowhole, capturing the droplets that sprayed out.

Using those unique breath samples captured over a four-year period, the study identifies an array of bacteria and fungi contained in the exhaled breath of the small, distinct population of southern resident killer whales of the northeast Pacific Ocean.

The number of Puget Sound orcas has fluctuated in recent decades as they have faced threats from lack of prey, pollution and noise disturbance from vessels. The orcas were listed as endangered in 2005, and now number 78.

Scientists also found healthy bacteria in the breath samples but also worrisome drug-resistant ones such as salmonella and Staphylococcus aureus.

The whales swim through urbanized waterways and encounter a number of environmental stressors caused by humans, including everything from what gets flushed down toilets to agricultural runoff.

"They're recruiting the bacteria in their habitats," said Stephen Raverty, the study's lead author who is a veterinary pathologist with British Columbia Ministry of Agriculture, Animal Health Centre in Abbotsford.

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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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Keeping Killer whales in zoos and aquariums has become highly controversial.

Keeping Killer whales in zoos and aquariums has become highly controversial. In a new paper, experts outline several novel ideas for improving the lives of Killer whales in zoological institutions by enhancing the communication, feeding, environment, and health of the animals in order to elicit natural behaviours seen in the wild.

"The fact that these animals can be kept in captivity is amazing in itself from a zoological perspective. We are now moving into a time when animals that we could not conceive being kept in zoological institutions are becoming relatively common; however once the difficult initial stages of keeping them alive have been achieved, people want to know that their psychological and physical welfare is also being considered," said Prof. Graham Law, co-author of the International Zoo Yearbook article. "So a change in the way that animals have been kept in captivity has been slowly evolving using environmental enrichment. For many species the changes have been great, but for other less well-understood species change has been slow as the need for change has been poorly understood."

With this Killer whale article, Prof. Law and his colleagues hope to start a process whereby people become more critical and questioning of the husbandry systems in place for all species in captivity, with the goal of achieving a better balance between their physical and psychological wellbeing.

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Materials provided by Wiley. Note: Content may be edited for style and length.

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Journal Reference:

G. Law, A. C. Kitchener. Environmental enrichment for Killer whales Orcinus orca at zoological institutions: untried and untested. International Zoo Yearbook, 2017; DOI: 10.1111/izy.12152

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