Bottlenose Dolphin Adopts Whale Calf of Another Species

Interspecies adoptions are rare, but it’s not the first time this population of dolphins in French Polynesia has attempted it.

From a small inflatable boat in the Rangiroa atoll in French Polynesia, Pamela Carzon got her first glimpse of the “strange” trio of marine mammals she’d been told about: a bottlenose dolphin mother (Tursiops truncatus), her seven-month-old calf, and another young cetacean that was slightly smaller and looked to be not a bottlenose dolphin at all, but a melon-headed whale (Peponocephala electra). 

It was April 2015, and Carzon and a colleague at the Marine Mammal Study Group of French Polynesia, a nongovernmental organization dedicated to whale and dolphin conservation, were out for the NGO’s annual photo-ID survey, very much hoping to find animals that a former collaborator had seen while diving in the region the previous November. “[T]he sea was very calm, and there were many dolphins around,” Carzon, also a PhD student at the Center for Island Research and Environmental Observatory (CRIOBE) in French Polynesia and the École Pratique des Hautes Études in Paris, recalls in an email to The Scientist. “It took us maybe two minutes to spot them: the dark calf was easy to spot among the bottlenose dolphins.”

DOLPHIN ADOPTION: A female bottlenose dolphin in the South Pacific has been sighted with both her own calf and another young cetacean identified as a melon-headed whale.

The mother, dubbed ID#TP25 by the researchers, was known to tolerate divers and boats, and that April day she approached the inflatable with both calves. Carzon grabbed her underwater camera and slipped into the water. “I was able to get good underwater footage and to sex both calves,” she says. ID#TP25’s natural calf was a female; the second calf was male. “I also noticed that both were ‘gently’ pushing each other [in order] to remain under the adult female’s abdomen” in so-called infant position. Continued observation over the following months revealed that the dolphin mom was nursing the foreign calf, whose species ID remains to be confirmed with genetic testing, and otherwise treated him as one of her own.

Carzon had been studying the bottle-nose dolphin community inhabiting the northern part of Rangiroa atoll for a decade and knew that the cetaceans had a history of bringing young animals of other species into their group. In 1996, researchers observed a newborn spinner dolphin (Stenella longirostrisswimming in the slipstream of an adult male bottlenose—a behavior known as echelon swimming and a common interaction between mothers and calves. Scientists also regularly spotted a juvenile spinner dolphin over the next two years, often with a particular adult female bottlenose, Carzon says, although it’s not clear whether it was the same individual they saw as a newborn. Then, in November 1998, a newborn melon-headed whale spent a few weeks in the area and was filmed swimming in echelon position with the same female bottlenose that had associated with the young spinner dolphin.

More recently, another adult female bottlenose in the same community has twice been seen with young of a different species. In January 2011, she was spotted with a neonate spinner dolphin for a few days, and in February 2018, she was photographed with a newborn Fraser’s dolphin (Lagenodelphis hosei), which swam alongside her in echelon position. With such behaviors apparently relatively common within this social group, ID#TP25 may have picked up a thing or two from her conspecific companions, speculates Carzon. “The evidence that bottlenose dolphins are capable of imitation is very strong,” she says. “[S]ocially transmitted ideas or practices from cultural models may have influenced [ID#TP25’s] behavior.” 

As is the case with most animal adoptions in the wild, how the mother bottlenose came to acquire the melon-headed whale calf is unknown. The calf’s natural mother may have died, or the bottlenose dolphin group may have “kidnapped” it, a behavior that was once observed in a dolphin group in the

Bay of Gibraltar, Carzon notes. Whatever scenario landed the outside calf in the care of dolphin ID#TP25, the adoption was stable, lasting more than two years. ID#TP25’s naturalcalf disappeared by early 2016, suggesting it died or weaned early, possibly joining another social group.

There is only one other published case of intraspecies adoption by animals in the wild: for about 14 months in the early 2000s, researchers documented the integration of an infant marmoset (Callithrix jacchus) into a group of capuchin monkeys (Cebus libidinosus) in woodland savanna of central Brazil. A female monkey that the researchers had thought was pregnant but who perhaps lost her own baby cared for the infant marmoset, carrying it on her back and appearing to nurse it. “It was amazing because when she appeared, she was tiny tiny tiny,” says Patrícia Izar, a primate ethologist at the University of São Paulo in Brazil who observed the adoption. “She was really a newborn, and she survived.” Izar says she was particularly astonished because she knew that some groups of capuchin monkeys eat young marmosets. Care for the young animal was eventually assumed by another female capuchin, and all group members appeared to tolerate the marmoset’s presence.

As for why intraspecies adoptions do—rarely—occur, wildlife conservation professor Robert Young of the University of Salford in the UK suggests that animals may not recognize that they’re caring for young of another species. In the case of the dolphins, the presumed melon-headed whale is similar in size to the adoptive mother’s own bottlenose dolphin calf, and the dolphins have not evolved a strong ability to differentiate their own young from those of another species. “There’s good reason to think it’s just an identification problem,” says Young, who says he has observed a handful of intraspecies adoptions among black-fronted titi monkeys (Callicebus nigrifrons) in Brazil.

The high levels of oxytocin coursing through mammalian mothers’ bodies and the abundance of resources are also likely to be relevant factors. Indeed, in the case of the capuchin group that took in a marmoset baby, Izar and her colleagues had been providing coconuts to study the animals’ use of stones to crack the fruit open, meaning that the monkeys had plenty of food to eat, and so looking after additional young might have been less costly. Interspecies adoptions are also much more common among domestic and captive animals, for whom food is often plentiful, than they are in the wild, Young notes. “If you’ve got a lactating female dog, you can just about get it to rear any other mammal.”

Documented cases of interspecies adoption among the Rangiroa dolphins and Brazilian monkeys “shows that it’s not impossible,” says Izar. “I think that in time we will have other cases in the wild.”

The adoption was stable, lasting more than two years.



sorce: https://www.the-scientist.com/

Banned toxins passed from mother to young in European dolphins

Dolphins in the northern Adriatic contain high levels of PCBs – highly toxic chemicals banned in the 1970s and 1980s – and are passing the pollutant to their young, according to new research led by a marine scientist at the University of St Andrews.

An international team of researchers evaluated PCB and other organochlorine contaminants in bottlenose dolphins (Tursiops truncatus) living in the Gulf of Trieste (northern Adriatic Sea), the northernmost part of the Mediterranean Sea and one of the most human-impacted areas in the Mediterranean.

They found that, overall, 87.5% of dolphins had PCB concentrations above the toxicity threshold for the onset of physiological effects in marine mammals, while 65.6% had concentrations above the highest threshold published for marine mammals based on reproductive impairment in seals. Such high contaminant levels are of concern, particularly in combination with other threats to dolphins, including bycatch in fisheries, disturbance by boat traffic, and prey depletion.

The research, published in the journal Science of the Total Environment, involved Morigenos – Slovenian Marine Mammal Society (Slovenia), the Sea Mammal Research Unit at the University of St Andrews (UK), the Zoological Society of London’s Institute of Zoology (UK), the Centre for Environment, Fisheries and Aquaculture Science (CEFAS, UK) and the Institute of Marine Sciences of the Italian National Research Council (Italy).

Tilen Genov, lead author of the study and a PhD student at the University of St Andrews, said: “We have been studying these dolphins for over 16 years, so we know most of them well. Through long-term re-sighting histories of identified individuals, we were able to link PCB levels in individual dolphins to parameters such as sex, reproductive output and social group membership.

“The research showed that males have significantly higher pollutant concentrations than females. This is because females offload a substantial amount of their toxicological burden to their young through gestation and lactation.

“That is also why females that have not yet had calves had significantly higher concentrations than those that had previously produced at least one calf. Such results are expected based on our knowledge of mammal physiology, but it is not very common to demonstrate this phenomenon in wild whales and dolphins.”

Dr Paul Jepson, co-author of the study and specialist wildlife veterinarian at the Zoological Society of London’s Institute of Zoology, said: “This is another study showing high or very high levels of a very toxic and persistent pollutant – PCBs – in European dolphins. PCBs have the ability to cause diseases like cancer and can also suppress reproduction.”

source: news.st-andrews.ac.uk

Discover why whales get stranded

A new study reported in the journal Current Biology on February 24 offers some of the first evidence that grey whales might depend on a magnetic sense to find their way through the ocean. This evidence comes from the discovery that whales are more likely to strand on days when there are more sunspots.

Sunspots are of interest because they are also linked to solar storms — sudden releases of high-energy particles from the sun that have the potential to disrupt magnetic orientation behaviuor when they interact with Earth’s magnetosphere. But what’s unique about the new study, according to the researchers, is that they were able to explore how a solar storm might cause whales to strand themselves.

“Is it that the solar storms are pushing the magnetic field around and giving the whales incorrect information — for example, the whale thinks it is on 4th Street, but it is actually on 8th?” asks Jesse Granger of Duke University. “Or is it that the solar storms are messing up the receptor itself — the whale thinks it is on 4th Street, but has just gone blind?

“We show that the mechanism behind the relationship between solar storms and grey whales, if it is an effect on a magnetic sensor, is likely caused by disruption to the sense itself, not inaccurate information. So, to put this back into the earlier metaphor, the big secondary finding of this paper is that it is possible that the reason the whales are stranding so much more often when there are solar storms is because they have gone blind, rather than that their internal GPS is giving them false information.”

Granger says her interest in long-distance migrations stems in part from her own personal tendency to get lost, even on her way to the grocery store. She wanted to explore how some animals use magnetoreception to navigate by looking at incidents when navigation went terribly wrong.

“I hypothesized that by looking at patterns in the spacing and timing of incidents where an animal was unable to navigate properly, we could better understand the sense as a whole,” Granger says.

She and her colleagues studied 186 live stranding of the grey whale (Eschrichtius robustus). The data showed those stranding occurred significantly more often on days with high sunspot counts than on randomly chosen days. On days with a high sunspot count, the chance of a stranding more than doubled.

Further study showed that stranding happened more often on days with a high solar radio flux index, as measured from Earth, than on randomly chosen days. On days with high RF noise, the likelihood of stranding was more than four times greater than on randomly selected days.

Much to Granger’s surprise, they found no significant increase in stranding on days with large deviations in the magnetic field. Altogether, the findings suggest that the increased incidence of stranding on days with more sunspots is explained by a disruption of whales’ magnetoreceptive sensor, rather than distortion of the geomagnetic field itself.

“I really thought that the cause of the stranding was going to be inaccurate information,” Granger said. “When those results came up negative, I was flummoxed. It wasn’t until one of my co-authors mentioned that solar storms also produce high amounts of radio-frequency noise, and I remembered that radio-frequency noise can disrupt magnetic orientation, that things finally started to click together.”

Granger says it’s important to keep in mind that this isn’t the only cause of stranding. There are still many other things that could cause a whale to strand, such as mid-frequency naval sonar.

Granger now plans to conduct a similar analysis for several other species of whales on several other continents to see if this pattern exists on a more global scale. She also hopes to see what sort of information this broader picture of stranding can offer for our understanding of whales’ magnetic sense.

Source: https://www.sciencedaily.com/

Image: https://abcnews.go.com/

Sperm whaling

Educational-Trainers self-development

Many of our members ask why whaling is still permitted and why they do it?

Here I share some information with you, so you have an idea why!!

Sperm whaling is the hunting of these marine mammals for the oil, meat and bone that can be extracted from their bodies. Sperm whales, a large and deep-diving species, produce a waxy substance that was especially useful during the Industrial Revolution, and so they were targeted in 19th-century whaling, as exemplified in Moby Dick. Sperm oil is no longer needed, but another unusual product, ambergris, is still valued as a perfume fixative. Although the animal is classified as a vulnerable species, aboriginal whaling in limited numbers is still permitted, notably from two villages in Indonesia, for subsistence.

Sperm whales were hunted in the 19th century by American, British and other national whaling fleets. As with all the species targeted, the thick layer of fat (blubber) was flensed (removed from the carcass) and rendered, either on the whaling ship itself, or at a shore station. This was the whale oil, stored in casks for the long journey home. It was sold as a lamp fuel, not a food product; the whale meat was discarded. The other species that were within reach during the Age of Sail were filter-feeders, and their baleen had many commercial uses. The sperm whale, being a toothed hunter, lacked this so-called whalebone, but it did produce a valuable commodity: sperm oil.

Each whale’s head held up to a ton, in a cavity called the “case”. It was part of a waxy liquid called spermaceti, from which the whale got its common name. The liquid was removed from the spermaceti organ at sea, and stored separately from the rendered whale oil for processing back in port. On return home, this headmaster, which was worth around 20% more than the oil from the blubber, was divided into two valuable commodities. One was a very pure type of sperm whale oil that required little or no additional processing. It was found particularly suitable as a lubricant for fine machinery, such as pocket watches. What remained after the oil was extracted was a waxy substance that could be made into spermaceti candles. These burned longer and brighter than tallow candles and left no smell and, as a result, sold at a higher price.[1] Although spermaceti by-products were high-value, they made up only a small proportion, perhaps 10%, of the substances extracted from sperm whales.

This product had a variety of commercial applications. In addition to the manufacture of candles, spermaceti was used in soap, cosmetics, machine oil, other specialized lubricants, lamp oil, paint, putty, pencils, crayons, leather waterproofing, rust-proofing materials and many pharmaceutical compounds.

Two other products of the sperm whale are of economic importance. Ambergris, a solid, waxy, flammable substance produced in their digestive system, was also sought as a fixative in perfumery. The whales’ teeth were carved by sailors into scrimshaw art.

Source: Wikipedia

Image: google.com

Chinese white dolphin population dwindling, says govt report


The number of Chinese white dolphins in Hong Kong waters has been decreasing, according to the latest official statistics, suggesting that government efforts to preserve the endangered species appear to be making little headway.

According to the 2016/17 Marine Mammals Monitoring Report published by the Agriculture, Fisheries and Conservation Department (AFCD), there were only 47 sightings of Chinese white dolphins in the waters off Lantau, where they tend to appear most often.

The number represented a 27 percent drop from the previous year and the lowest since 2002. There were no sightings for the second year in a row in the northeast waters of Lantau, where the main construction work for the Hong Kong-Zhuhai-Macau Bridge is taking place

In 1997, the Chinese white dolphin was chosen as the mascot to mark Hong Kong’s return to Chinese rule. It is listed among the wild animals under Grade 1 conservation according to Chinese law.

To prepare the report on marine mammals, researchers conducted a total of 178 line-transect vessel surveys in 10 survey areas in Hong Kong waters between April 2016 and March 2017.

Of the 1,233 dolphins sighted during the 12-month period, including Chinese white dolphins, only 17 were unspotted juveniles.

These young calves comprised only 1.4 percent of the total, compared with nearly 8 percent in 2003, suggesting the population of dolphins may dwindle in the future.

Dr. Samuel Hung Ka-yiu, chairman of the Hong Kong Dolphin Conservation Society and lead writer of the AFCD report, said the construction of the Hong Kong-Zhuhai-Macau Bridge has had a great impact on the habitat of the Chinese white dolphin, according to hk01.com.

Construction of the planned third runway and the high-speed ferries that regularly pass the waters are further threats to the animals’ survival, Hung said.

To help preserve the dolphins, Hung urged the government to establish a large marine protected area in West Lantau waters.

“Habitat destruction from expanding reclamation work in Lantau waters and the hi-speed marine traffic in the area have increased the stress on the dolphin population,” the World Wide Fund for Nature (WWF) said. “The underwater noise generated inhibits their echolocation capability.”

These disturbances threaten the survival of the remaining dolphins in Hong Kong waters, said Samantha Lee, WWF-Hong Kong conservation manager for oceans.

WWF-Hong Kong urges the government to establish the West Lantau Marine Park as soon as possible to protect the remaining dolphin habitats.

source: https://www.ejinsight.com/

Measuring a dolphin is also called Morphometric

Morphometric data is a way of estimating and managing animal body mass with high levels of accuracy.

Measurements of wild dolphins were used to generate sex‐specific body mass reference ranges. Gompertz growth models were fitted to know length measurements and age to compare growth across populations.