Tag Archives: sperm whale

How sperm whales outwitted whalers by sharing tactics between them

While constantly harassed by hunters, sperm whales during the 19th century were clever enough to learn how to avoid the ships — and social enough to share this information with other whales. This led to a significant drop in the strike rate of harpooners in just a few years and might have avoided more whales being killed, a new study reveals.

Image credit: The researchers

Sperm whales (Physeter macrocephalus) are considered the largest of all toothed whales, having the widest global distribution of any marine mammal species. They can be found in all deep oceans and are names after the waxy substance (spermaceti) found in their heads – which was used to make oil lamps, lubricants, and candles.

They were the main target of the commercial whaling industry from 1800 to 1987, as exhibited in the legendary Moby Dick book. Whalers from Europe and North America spread around the world looking for new grounds and new species. Once sighted, whalers stroke them with hand-thrown harpoons and towed them back to the boat to be processed.

Some historians have suggested that the success rate of open-boat whalers in harpooning sighted whales dropped substantially during the initial years of industrial exploitation and that this was due to socially learned changes in whale behavior. Proving this belief was the main goal of a group of United States researchers.

Researchers led by Hal Whitehead, a professor of biology at Dalhousie University in Nova Scotia, analyzed newly-digitized logbooks kept by whalers during their hunting voyages in the North Pacific. They found that the strike rate of the whalers’ harpoons fell by 58% in just a few years – which they link to the whales sharing information between them.

Whitehead explained the whales at first reacted to the threat of the hunters as they would to the killer whale, which was their single predator back then. The whales gathered together on the surface, put the baby in the middle, and slapped their tales to defend themselves. By doing so, they made themselves an easy target to the vessels.

But the whales eventually learned from their mistakes, according to the study. They adapted to their new predator by implementing a new tactic, swimming fast upwind and away from the whalers’ wind-powered vessels. The tactic soon spread around the whale community, with whales learning getaway techniques from each other.

This isn’t random, as sperm whales are excellent at sharing information. They have a highly observant and communicative nature, and the fact that each family unit only stays in larger groups for a few days at a time means they can share information fast. They have the largest brains on the planet, so they likely knew what was going on.

“Each whale group that you meet at sea typically comprises two or three family units, and the units quite often split off and form other groups,” Whitehead told Live Science. “So, what we think happened is that one or two of the units that make up the group could have had encounters with humans before, and the ones who didn’t copy closely from their pals who had.”

Commercial whaling largely decreased the sperm whale population worldwide, with the best estimate now being between 300,000 and 450,000 individuals. A moratorium was placed on whaling in 1986 and species have been recovering since then. Still, other threats remain such as longline fishing, noise pollution, and the changing source of their food due to climate change.

The paper was published in the journal Biology Letters.

A Sperm Whale Found Dead in Spain Had 30 Kilos of Plastic in Its Stomach

Have you ever wondered where your plastic ends up? The words “inside a young male sperm whale that was found dead off the coast of Spain” probably don’t pop to mind but this is, once again, a dire reminder that our pollution has a great price — and that price is often paid by wildlife.

Sperm whale found dead on a beach at Cabo de Palos in Murcia. Credits: Murcia regional government, CARM.

The sperm whale washed off the Murcia coast in Spain in February. Biologists have recently carried out an autopsy on the whale, and among other things, they’ve discovered plastic bags, a jerry can, several pieces of rope and net, and even a drum. The amount of human trash was enormous, reaching about 30 kilograms (66 pounds). As the experts from the El Valle Wildlife Recovery Center confirmed, the plastic itself killed the whale — the unfortunate creature simply ingested too much plastic and couldn’t expel it. It appears that the plastic caused a blockage in the whale’s digestive system which led to an infection that ultimately proved fatal.

The case triggered a national awareness campaign against single-use plastic, which often ends up in our oceans, and inside unfortunate creatures like this sperm whale.

“The presence of plastics in seas and oceans is one of the greatest threats to the conservation of wildlife throughout the world, since many animals are trapped in the trash or ingest large amounts of plastics that end up causing their death,” said Consuelo Rosauro, director-general of the natural environment in the Murcian government.

“The region of Murcia is no stranger to this problem, which we must tackle through clean-up actions and, above all, citizen awareness.”

In the grand scheme of things, this should come as no surprise — we know there is already an ungodly amount of plastic in the oceans. A previous study found that there are over 5 trillion plastic pieces in the ocean, leading the ocean floor to become a plastic cemetery. With 8 million tons of plastic ending up in the ocean every year, researchers expect that by 2050, there will be more plastic than fish in the oceans.

While scientists are unsure exactly how much harm this plastic is causing, more and more evidence suggests that wildlife is greatly suffering and there are myriad examples of whales washing up on the beach with stomachs full of plastic. Birds, turtles, fish — nothing is spared from the ever-growing mountain of plastic. But there are some reasons for optimism.

In England, a $0.05 tax on plastic bags caused a massive drop in plastic bag usage, and elsewhere in the world, similar results are being observed. There are ways to reduce our plastic usage, but it requires strong, systematic efforts in all layers of society. Policymakers, corporations, and us, the citizens, all need to play our part.

How northern lights and stranded whales might strangely be connected

Researchers found an unlikely connection between stranded whales and the Northern Lights.

The northern lights might be a brilliant spectacle for some, but they might have spelled doom for some unfortunate sperm whales. Credits: NASA.

In early 2016, the stranding of 29 sperm whales in the North Sea left researchers surprised, since these whales are not normally found in that part of the world. None of them survived. Autopsies revealed that the whales were all in pretty good health, so the exact reason why they became stranded in shallow waters remained a mystery. Now, researchers proposed an unexpected culprit: geomagnetic storms.

Sperm whales live in temperate to warm waters all year long. They tend to migrate between the warmer equatorial waters and the colder but squid-rich waters of the Norwegian sea. The North Sea isn’t really on their list, and neither is it on the list of Gonatus fabricii squid — their preferred food — so it doesn’t make much sense to venture that far. They normally stick to the western side of Great Britain, whereas the North Sea is more to the east. That fatal mistake might be explained through magnetic fields.

The magnetic map of where the Norwegian and North Seas join. The whales should have traveled along the white arrow, but instead traveled along the red arrow. Credit: Vanselow et al.

The Earth’s magnetic field is not uniform — it has numerous anomalies, both positive and negative, big and small. It’s thought that some creatures use this field to navigate through their migration, but this technique can be severely disturbed by solar storms, which produce huge differences that totally confuse the animals. This is a relatively new concept, but it has been previously documented in both birds and bees. Dolphins also seem to use the magnetic field, so it would make sense for whales to do it too.

Dr Klaus Vanselow from the University of Kiel, Germany, believes this is also what happened to the whales. He and his team claim a large solar storm distorted the magnetic field, causing the unfortunate mammals to lose their way in the sea. The same solar storm produced spectacular northern lights, visible from the Arctic down to Scotland.

Specifically, they identified two such storms occurring on December 20/21, 2015, and December 31 and January 1, 2015/2016. They found that the anomalies caused by these storms stretched down to the Shetland Islands, where the whales would have turned right (east) instead of left (west). Normally, the whales would sense a magnetic barrier in front of the North Sea and avoid diving into it, kind of like a magnetic mountain. However, the storms “leveled” these magnetic mountains, rendering them invisible for the whales.

This misstep was all it took.

“Sperm whales are very huge animals and swim in the free ocean so if they are disrupted by this effect, they can swim in the wrong direction for days and then correct it,” says Vanselow. “But in the area between Scotland and Norway, if the whales swim in the wrong direction for one or two days, then it is too late for them to go back, they are trapped.”

This seems to fit very well with the timeline of the whales but of course, correlation does not imply causation. We still don’t know exactly how the whales detect and operate based on this magnetic field, and just because this seems to fit doesn’t mean it is indeed what happened.

“It would be difficult to say that ‘yes this was the cause’, we would be cautious in saying that,” said Abbo Van Neer from the University of Hannover who carried out the autopsies on the 16 whales that stranded in Germany. “But it is a valid hypothesis and a potential reason for the stranding.”

In other words, it’s a properly designed study that offers a solid hypothesis, but it doesn’t really prove anything. Dr Antti Pulkkinen, who is leading a NASA effort to investigate the link between strandings in Cape Cod and geomagnetic storms, says there’s just not enough data to draw a definite conclusion.

“Having looked at this problem from a data analysis point of view, it is not a single factor that contributes to this. Things need to line up from multiple different perspectives for these events to take place.”

Journal Reference: Klaus Heinrich Vanselow, Sven Jacobsen, Chris Hall and Stefan Garthe. Solar storms may trigger sperm whale strandings: explanation approaches for multiple strandings in the North Sea in 2016. DOI: https://doi.org/10.1017/S147355041700026X

 

Underwater photographer Franco Banfi captured these amazing images of the 45 tonne mammals swimming close to the island of Dominica.

Sperm whales clans have different dialects

A insightful incursion into the lives of sperm whales shows just how similar these gentle marine giants are to us. Not only do these highly social animals communicate through a language, made up of patterned sets of clicks called codas, but they also have dialects. These dialects may be unique to each clan of sperm whales, which may include thousands of individuals. Moreover, the language is learned and not inherently transmitted – a prime example of culture, if anything else.

Underwater photographer Franco Banfi captured these amazing images of the 45 tonne mammals swimming close to the island of Dominica.

Underwater photographer Franco Banfi captured these amazing images of the 45 tonne mammals swimming close to the island of Dominica.

The findings were made by researchers at the Dalhousie University in Halifax, Canada who closely followed clans of sperm whales off the Galapagos Islands in the eastern Pacific. The scientists carefully recorded and analyzed the whales’ codas, which sound very much like Morse code as the clicks vary in rhythm and tempo. Two clans particularly stood out. In one clan the pattern of clicks were regularly spaced, but in the other the codas had an extended pause at the end before the last click. But do they understand each other? To a degree maybe, but unlikely.

“They behave differently; they move around differently; they babysit their babies differently,” Prof Hal Whitehead of Dalhousie told the BBC. “And so while a family unit from the regular clan will get together with another family unit from the same clan, sometimes for days – and the same for the plus-ones – we’ve never seen a regular unit associate with a plus-one unit.”

An important question the researchers wanted to answer is whether the ‘clicking’ ability to communicate with distinct codas is inherent or attained. So they built two models in which virtual sperm whales lived in a simulated environment analogous to the real one.

“In one of our scenarios, we had genetic transmissions of codas from mothers to their calves; and in other scenarios we had whales creating their vocal repertoires on their own or learning from each other,” said PhD student Maurício Cantor.

“And our results suggest only when we have whales learning from each other, or copying bits of their coda types, can we have, over time, these different dialects.”

Is this direct evidence that sperm whales form a culture – maybe the first in the animal kingdom besides human society? It’s a complex question in biology today and “it all depends on how you define culture,” says Cantor.

These findings are amazing, neverthless. They show just how complex these animals are, and given how social they are this might not be that surprising when you ponder it. Just look at us, there might be a correlation between our extraordinary ability to communicate and our intricate social structure.

The whales dive the deepest and longest, plus they have the largest brains, largest noses, and the most powerful sonar in the animal world. “All of this makes them very effective predators, but also very cooperative and social creatures,” says Cantor.

Both genders are sexually mature in their early teens, which is when many males leave their natal social unit. Males spend the next 15 years wandering, generally moving to colder and colder waters; they range from pole to pole. But sometimes, males will form a bachelor clique. The females, on the other hand, never leave their social unit essentially comprised of mothers, grandmothers, daughters and pre-teens.

The beautiful sperm whales almost got hunted to extinction, being valued for their oil. While international banning has mostly pulled the plug, some illegal harpooning still takes place. Pollution, chemical dumping – particularly heavy metals like mercury – and trash (whales regularly get trapped in fishing gear) are the biggest threats sperm whales face today.