‘Like trying to find the door in a dark room while hearing your relatives scream for help’: Tasmania’s whale stranding tragedy explained


Olaf Meynecke, Griffith University

A desperate rescue effort is underway after hundreds of long-finned pilot whales (Globicephala melas) became stranded in Macquarie Harbour on Tasmania’s west coast.

Yesterday, more than 250 pilot whales were reported to have stranded, with one-third presumed dead. And this morning, rescuers found another 200 pilot whales stranded up to ten kilometres away from the first group — most are likely dead.

This brings the total number of stranded pilot whales in Tasmania to more than 450, and it’s believed to be the biggest ever recorded in the state. The Greens are calling on federal Environment Minister Sussan Ley to launch a national response.

The rescue mission aims to refloat the pilot whales that appear to still be in reasonable health. But their behaviour hampers rescue efforts: many pilot whales re-strand themselves to be with their family. This event likely means a number of generations of the local population will be lost.




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How did they become stranded?

Despite its name, the long-finned pilot whale is actually a large oceanic dolphin. They cover vast areas of the Southern (Antarctic) Ocean, reaching between four and six metres in length and weighing up to one tonne.

They are well adapted to deeper oceans where they hunt for various species of squid in depths of between 600-1,000m, using echolocation to find their prey. Echolocation is a way of using sound to navigate in complete darkness.

They generally spend most of their lives offshore and it’s not well understood what conditions drive them close to shore, and to enter shallow embayments.

Some theories suggest food shortages are to blame, or changes in electromagnetic fields that disorient them. They may also be following a sick or distressed pod leader. And in some past cases strandings were related back to active sonar from ships and naval sonar interrupting their echolocation.




Read more:
What causes whale mass strandings?


But once in shallow waters, it’s difficult to swim back out. As these whales mostly navigate with echolocation it’s not possible for them to use sonar effectively in shallow and muddy embayments.

It’s extremely distressing for the whales, a lot like trying to find the door in a dark room while hearing your relatives scream for help.

In fact, the stress is what many die from in the end. Other causes of death are overheating from sun exposure and drowning if they can’t move their bodies up to breach the surface in shallow water.

The rescue efforts

There are a number of strategies to refloat whales. In Macquarie Harbour, rescuers are using slings to tow the whales to deeper water, before releasing them.

Other options include multiple people pushing them off the beach during high tide into deeper water.

In this case, albeit potentially dangerous for the helpers, people power can make a big difference. After all, time is of immense importance for success, and to stop more whales beaching.

However, chances of survival plummet with long exposure to sun and extended periods of stress. What’s more, Macquarie Harbour is relatively remote and difficult to access, further complicating rescue efforts.

Dying together

But the biggest obstacle rescuers face is the whales’ social bonding. Long-finned pilot whales are highly intelligent and live in strong social units.

So when dealing with mass strandings, it’s important to realise the emotions and bonding between the whales are very likely beyond what humans can feel. One well-documented example of their emotional depth is the pilot whale seen carrying its dead calf for many days.

Mother pilot whale grieves over her dead calf.

This makes the stranding process extremely complex, as it unfolds over several hours to several days — the whales don’t all strand at the same time.

We know from killer whales, which also have strong social bonding, that if a close member of the group strands, others will attempt to join to die together.




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We need to understand the culture of whales so we can save them


The situation for pilot whale pods can be similar, but more complex as a result of having much larger pods. Pilot whale pods have multiple sub-units, which can consist of friends as well as family and they don’t have to be genetically related.

Social units get mixed up when they’re in shallow bays. This means individuals can become disconnected from their social units before the actual stranding occurs, causing stress and confusion prior the beaching.

Fewer pilot whales in the gene pool

There are an estimated 200,000 long-finned pilot whales in the Southern Ocean and Antarctica, but mass strandings like this can have a profound impact on sub-populations.

In Tasmania alone, 1,568 long-finned pilot whales have stranded between 1990 and 2008 in 30 stranding events.

Many similar sad events occured in New Zealand: hundreds of long-finned pilot whales stranded in 2018 and 2017, and the majority died.

To make matters worse, studies suggest the long-finned pilot whales in the Southeastern Pacific have low genetic diversity. There are similarities between this species found in Chile and New Zealand, but with surprisingly distinct differences between New Zealand and Tasmania.

Considering they can live up to 50 years and the fact only few survive when multiple generations strand, such events not only destroy entire generations but also remove them from the gene pool.

This puts local populations at further risk. Inbreeding is one consequence, but the biggest problem is their decreasing general fitness and ability to adapt to changes.

How to help

In the past, significant numbers of stranded whales have been successfully released, making it worth the effort. For example, in one of largest mass strandings in New Zealand in 2017, volunteers helped about 100 whales refloat, and made a human chain to try to stop them restranding.




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Still, such events are likely to be more frequent in the future due to changing ocean conditions and increasing human activity such a noise pollution, commercial squid fisheries and deep sea mining.

Climate change shifts ocean currents as sea temperature rises. And with this, squid availability will change. A lack of food offshore can cause stress and drive them closer to shore.

We can help the whales not only by actively supporting rescue organisations such as ORRCA, but also by helping reduce carbon emissions, foster sustainable fisheries, reduce plastic pollution and advocate for marine sanctuaries.The Conversation

Olaf Meynecke, Research Fellow in Marine Science, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Swimming with whales: you must know the risks and when it’s best to keep your distance



Shutterstock/anna sanfeliu gozalvez

Chantal Denise Pagel, Auckland University of Technology; Mark Orams, Auckland University of Technology, and Michael Lueck, Auckland University of Technology

Three people were injured last month in separate humpback whale encounters off the Western Australia coast.

The incidents happened during snorkelling tours on Ningaloo Reef when swimmers came too close to a mother and her calf.

Swim encounters with humpback whales are relatively new in the Australian wildlife tourism portfolio. The WA tours are part of a trial that ends in 2023. A few tour options have also been available in Queensland since 2014.

But last month’s injuries have raised concerns about the safety of swimming with such giant creatures in the wild.

Close encounters

Until recently, you had to travel to Tonga, Niue or French Polynesia for similar humpback whale encounters in Oceania. Or you could swim with other species, such as dwarf minke whales on the Great Barrier Reef.




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But when we interact with wild animals there is always a risk to safety, especially in challenging environments such as open water.

Whales, like other wildlife, may behave unpredictably. Active surface behaviours such as breaching, tail and fin slaps present a significant risk for swimmers and whale watchers.

Four drawings of a humpback whale.
A humpback whale (1) breaching, (2) head lunge, (3) tail slap and (4) pectoral fin slap can all be a danger to people close by.
Chantal Denise Pagel, Author provided

In one of the WA encounters, the nursing female was reported to display pectoral fin and tail slaps. These are potentially threatening due to the size (up to 16 metres long) and power of humpback whales.

These behaviours are frequently observed in social interactions between humpback whales and can present a severe risk of injury to anyone close by, with potentially life-threatening results.

A recent study of the impacts of swimmer presence on humpback whales off Réunion Island (on Madagascar’s east coast in the Indian Ocean) confirmed a high occurrence of aggressive and/or defensive whale behaviour.

The researchers observed flipper and tail fluke swipes and thrashes – sudden movements of a whale’s extremities – especially in mother-and-calf pairs.

A humpback whale slaps its pectoral flipper and splashes the water
Active whale behaviour is exciting to observe, but that flipper can pack a powerful punch.
Flickr/Michael Dawes, CC BY-NC

Keep your distance

While the reasons for the Australian incidents are still unclear, a possible explanation could be that the swimming groups approached the whales too closely and ignored the signs the whales did not welcome visitors.

Maintaining a safe distance should be required of any tourists interested in seeing or getting close to unpredictable wildlife, especially in unfamiliar environments.

We cannot expect tourists, who are often first-time whale swim participants, to be able to read and interpret whale behaviour. So it is vital that crew members are skilled and experienced and can end an encounter if it needs to be.

Knowledgeable in-water guides are indispensable in commercial swim-with-whales programs. Yet this is often not a requirement by organisations issuing licenses for such activities.

For example, permits in New Zealand require “knowledgeable operators and staff”, but there is no requirement to have guides in the water during the encounter. People interested in swim-with-whale encounters should choose tour companies that provide in-water guides who join them in their adventure.

We should also question whether interactions with female whales caring for newborn calves should be allowed. Best-practice guidelines advise against interactions where calves are present.

A mother humpback whale underwater with her calf.
We need to be extra careful when near a mother humpback whale with her calf.
Shutterstock/Lewis Burnett

Recent research in the popular whale-swim destination Tonga showed mother-and-calf pairs avoid about one-third of tour vessel approaches by diving for longer periods.

Yet surface resting times are critical for calves. Any decrease in time spent resting for mother-and-calf pairs can affect a calf’s growth rate, overall fitness and chances of survival.

Similar observations were made in Réunion. Three out of four (74%) mother-calf-pairs changed their behaviour to avoid swimmers.

Safety first: for whales and swimmers

The Pacific Whale Foundation is undertaking a study to assess the impact of swimming with humpback whales in Hervey Bay, Queensland, Australia.

This research is to monitor the behaviour of humpback whales, providing critical insights into whether tourism activities add stress to this recovering population.




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But research into the suitability of wildlife species used for commercial tourism operations and their health and safety provisions still lacks fundamental depth.

In highly interactive tourism activities such as swim-with-wildlife programmes, tourists should receive education about the risks involved in these “bucket list” experiences. This should include information on animal behaviour and the potential consequences for swimmers.

Furthermore, training tour operators to identify behaviours that may indicate disturbance or have the potential to be harmful to clients is an important additional step towards safer interactions.The Conversation

Two images of a humpback whale breaching the water and one of a whale tail raised above the water.
Humpback whale breaching and tail slap.
Flickr/Grant Matthews, CC BY-NC-ND

Chantal Denise Pagel, Doctoral student | Marine Wildlife Tourism Professional, Auckland University of Technology; Mark Orams, Acting Dean, Health and Environmental Sciences, Auckland University of Technology, and Michael Lueck, Professor of Tourism, Auckland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Whales and dolphins found in the Great Pacific Garbage Patch for the first time



Adult and infant sperm whales have been spotted in the Great Pacific Garbage Patch.
Inf-Lite Teacher/Flickr, CC BY-SA

Chandra Salgado Kent, Edith Cowan University

Scientific research doesn’t usually mean being strapped in a harness by the open paratroop doors of a Vietnam-war-era Hercules plane. But that’s the situation I found myself in several years ago, the result of which has just been published in the journal Marine Biodiversity.

As part of the Ocean Cleanup’s Aerial Expedition, I was coordinating a visual survey team assessing the largest accumulation of ocean plastic in the world: the Great Pacific Garbage Patch.




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When the aircraft’s doors opened in front of me over the Pacific Ocean for the first time, my heart jumped into my throat. Not because I was looking 400m straight down to the wild sea below as it passed at 260km per hour, but because of what I saw.

This was one of the most remote regions of the Pacific Ocean, and the amount of floating plastic nets, ropes, containers and who-knows-what below was mind-boggling.

However, it wasn’t just debris down there. For the first time, we found proof of whales and dolphins in the Great Pacific Garbage Patch, which means it’s highly likely they are eating or getting tangled in the huge amount of plastic in the area.

The Great Pacific Garbage Patch

The Great Pacific Garbage Patch is said to be the largest accumulation of ocean plastic in the world. It is located between Hawaii and California, where huge ocean currents meet to form the North Pacific subtropical gyre. An estimated 80,000 tonnes of plastic are floating in the Great Pacific Garbage Patch.




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Our overall project was overseen and led by The Ocean Cleanup’s founder Boyan Slat and then-chief scientist Julia Reisser. We conducted two visual survey flights, each taking an entire day to travel from San Francisco’s Moffett Airfield, survey for around two hours, and travel home. Along with our visual observations, the aircraft was fitted with a range of sensors, including a short-wave infrared imager, a Lidar system (which uses the pulse from lasers to map objects on land or at sea), and a high-resolution camera.

Both visual and technical surveys found whales and dolphins, including sperm and beaked whales and their young calves. This is the first direct evidence of whales and dolphins in the heart of the Great Pacific Garbage Patch.

Mating green turtles in a sea of plastics.
photo by Chandra P. Salgado Kent, Author provided

Plastics in the ocean are a growing problem for marine life. Many species can mistake plastics for food, consume them accidentally along with their prey or simply eat fish that have themselves eaten plastic.

Both beaked and sperm whales have been recently found with heavy plastic loads in their stomachs. In the Philippines, a dying beaked whale was found with 40kg of plastic in its stomach, and in Indonesia, a dead sperm whale washed ashore with 115 drinking cups, 25 plastic bags, plastic bottles, two flip-flops, and more than 1,000 pieces of string in its stomach.

The danger of ghost nets

The most common debris we were able to identify by eye was discarded or lost fishing nets, often called “ghost nets”. Ghost nets can drift in the ocean for years, trapping animals and causing injuries, starvation and death.

Crew sorts plastic debris collected from the Great Pacific Garbage Patch on a voyage in July 2019.
EPA/THE OCEAN CLEANUP

Whales and dolphins are often found snared in debris. Earlier this year, a young sperm whale almost died after spending three years tangled in a rope from a fishing net.

During our observation we saw young calves with their mothers. Calves are especially vulnerable to becoming trapped. With the wide range of ocean plastics in the garbage patch, it is highly likely animals in the area ingest and become tangled in it.

It’s believed the amount of plastics in the ocean could triple over the next decade. It is clear the problem of plastic pollution has no political or geographic boundaries.




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While plastics enter the sea from populated areas, global currents transport them across oceans. Plastics can kill animals, promote disease, and harm the environment, our food sources and people.

The most devastating effects fall on communities in poverty. New research shows the Great Pacific Garbage Patch is rapidly growing, posing a greater threat to wildlife. It reinforces the global movement to reduce, recycle and remove plastics from the environment.

But to really tackle this problem we need creative solutions at every level of society, from communities to industries to governments and international organisations.

To take one possibility, what if we invested in fast-growing, sustainably cultivated bamboo to replace millions of single-use plastics? It could be produced by the very countries most affected by this crisis: poorer and developing nations.




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It is only one of many opportunities to dramatically reduce plastic waste, improve the health of our environments and people, and to help communities most susceptible to plastic pollution.The Conversation

Chandra Salgado Kent, Associate Professor, School of Science, Edith Cowan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids: which is smarter – a blue whale or an orca?



Blue whales and orcas are both specialists in their own way. You can’t really measure which one is more intelligent.
Shutterstock

Kerstin Bilgmann, Macquarie University

If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au.


Which is smarter: blue whales or orcas? – Prasaad, age 6.


There’s no simple answer. We don’t know for sure which one is smarter, because not everyone agrees on what “intelligence” means.

It’s true that blue whales and orcas (also called killer whales) are both smart. They both have very large brains. Orcas have particularly large brains compared to their overall body size.

But it’s not just about brain size. When it comes to measuring intelligence, we might also consider things like:

  • the number of nerve cells in the brain;
  • ability to navigate the deep, wide oceans;
  • solving difficult problems;
  • communicating;
  • working in teams.

Let’s look at which animal is good at which skill.




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Curious Kids: What sea creature can attack and win over a blue whale?


What can a blue whale do?

There’s no doubt a blue whale is a very intelligent animal.

Blue whales eat krill, which are very tiny prawn-shaped animals that gather in huge swarms that are often far away from where blue whales give birth to their children. Despite the distance, blue whales are masters of finding krill. They are very good at navigating along coasts and across the deep, wide oceans.

In fact, blue whales are so smart they can work out if a swarm of krill is worth chasing. Blue whales are very good at finding krill that are fat and in big swarms so they do not waste their energy catching smaller swarms. Blue whales catch krill by rolling on their side and opening their mouths. It is a lot of work and they have to use a lot of energy to do it.

Blue whales also have excellent systems for communicating with each other.

What can an orca do?

Orcas are a kind of large dolphin and they have different strengths.

They are very good at working together. They form groups and hunt together for fish or other sea mammals – including whales. This is why they are called “killer whales”.

They are also expert communicators and have their own language – even certain noises that are used by a particular group of orcas to show they are in the group.

Orcas form groups and hunt together.
Shutterstock

They both are very intelligent in their own way

Some scientists have wondered if you could measure intelligence by looking at how well animals teach their children how to behave – for example, how to find food, fight or stay safe.

Orcas are masters at teaching their children exactly what to do. This involves things like hunting in groups or sneaking up on a seal and grabbing it before sliding back into the water.

However, blue whales are also good at teaching their offspring skills such as long-distance navigation – in other words, finding their way around the vast oceans.

Both blue whales and killer whales have their own special behaviours and skills. We really can’t say which one is more intelligent because both are very intelligent in their own way.




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Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.auThe Conversation

Kerstin Bilgmann, Lecturer in Biological Sciences, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

As Arctic ship traffic increases, narwhals and other unique animals are at risk


File 20180806 191019 48ky5r.jpg?ixlib=rb 1.1
A pod of narwhals (Monodon monoceros) in central Baffin Bay. Narwhals are the most vulnerable animals to increased ship traffic in the Arctic Ocean.
Kristin Laidre/University of Washington, CC BY-ND

Donna Hauser, University of Alaska Fairbanks; Harry Stern, University of Washington, and Kristin Laidre, University of Washington

Most Americans associate fall with football and raking leaves, but in the Arctic this season is about ice. Every year, floating sea ice in the Arctic thins and melts in spring and summer, then thickens and expands in fall and winter.

As climate change warms the Arctic, its sea ice cover is declining. This year scientists estimate that the Arctic sea ice minimum in late September covered 1.77 million square miles (4.59 million square kilometers), tying the sixth lowest summertime minimum on record.

With less sea ice, there is burgeoning interest in shipping and other commercial activity throughout the Northwest Passage – the fabled route that links the Atlantic and Pacific oceans, via Canada’s convoluted Arctic archipelago – as well as the Northern Sea Route, which cuts across Russia’s northern seas. This trend has serious potential impacts for Arctic sea life.

In a recent study, we assessed the vulnerability of 80 populations of Arctic marine mammals during the “open-water” period of September, when sea ice is at its minimum extent. We wanted to understand the relative risks of vessel traffic across Arctic marine mammal species, populations and regions. We found that more than half (53 percent) of these populations – including walruses and several types of whales – would be exposed to vessels in Arctic sea routes. This could lead to collisions, noise disturbance or changes in the animals’ behavior.

Map of the Arctic region showing the the Northern Sea Route and Northwest Passage.
Arctic Council/Susie Harder

Less ice, more ships

More than a century ago, Norwegian explorer Roald Amundsen became the first European to navigate the entire Northwest Passage. Due to the short Arctic summer, it took Amundsen’s 70-foot wooden sailing ship three years to make the journey, wintering in protected harbors.

Fast-forward to summer 2016, when a cruise ship carrying more than 1,000 passengers negotiated the Northwest Passage in 32 days. The summer “open-water” period in the Arctic has now increased by more than two months in some regions. Summer sea ice cover has shrunk by over 30 percent since satellites started regular monitoring in 1979.

Bowhead whale (Balaena mysticetus) in Disko Bay, West Greenland.
Kristin Laidre, CC BY

Arctic seas are home to a specialized group of marine mammals found nowhere else on Earth, including beluga and bowhead whales, narwhals, walruses, ringed and bearded seals and polar bears. These species are critical members of Arctic marine ecosystems, and provide traditional resources to Indigenous communities across the Arctic.

According to ecologists, all of these animals are susceptible to sea ice loss. Research at lower latitudes has also shown that marine mammals can be affected by noise from vessels because of their reliance on sound, as well as by ship strikes. These findings raise concerns about increasing vessel traffic in the Arctic.

Ringed seal (Pusa hispida) pup in Alaska.
NOAA

Sensitivity times exposure equals vulnerability

To determine which species could be at risk, we estimated two key factors: Exposure – how much a population’s distribution overlaps with the Northwest Passage or Northern Sea Route during September – and sensitivity, a combination of biological, ecological and vessel factors that may put a population at a higher risk.

As an illustration, imagine calculating vulnerability to air pollution. People generally are more exposed to air pollution in cities than in rural areas. Some groups, such as children and the elderly, are also more sensitive because their lungs are not as strong as those of average adults.

We found that many whale and walrus populations were both highly exposed and sensitive to vessels during the open-water period. Narwhals – medium-sized toothed whales with a large spiral tusk – scored as most vulnerable overall. These animals are endemic to the Arctic, and spend much of their time in winter and spring in areas with heavy concentrations of sea ice. In our study, they ranked as both highly exposed and highly sensitive to vessel effects in September.

Narwhals have a relatively restricted range. Each summer they migrate to the same areas in the Canadian high Arctic and around Greenland. In fall they migrate south in pods to offshore areas in Baffin Bay and Davis Strait, where they spend the winter making deep dives under the dense ice to feed on Greenland halibut. Many narwhal populations’ core summer and fall habitat is right in the middle of the Northwest Passage.

A pod of narwhals (Monodon monoceros) in central Baffin Bay. Narwhals are the most vulnerable animals to increased ship traffic in the Arctic during September.
NOAA/OAR/OER/Kristin Laidre

Vulnerable Arctic regions, species and key uncertainties

The western end of the Northwest Passage and the eastern end of the Northern Sea Route converge at the Bering Strait, a 50-mile-wide waterway separating Russia and Alaska. This area is also a key migratory corridor for thousands of beluga and bowhead whales, Pacific walruses and ringed and bearded seals. In this geographic bottleneck and other narrow channels, marine mammals are particularly vulnerable to vessel traffic.

Among the species we assessed, polar bears were least vulnerable to September vessel traffic because they generally spend the ice-free season on land. Of course, longer ice-free seasons are also bad for polar bears, which need sea ice as a platform for hunting seals. They may also be vulnerable to oil spills year-round.

Research in the harsh and remote Arctic seas is notoriously difficult, and there are many gaps in our knowledge. Certain areas, such as the Russian Arctic, are less studied. Data are sparse on many marine mammals, especially ringed and bearded seals. These factors increased the uncertainty in our vessel vulnerability scores.

We concentrated on late summer, when vessel traffic is expected to be greatest due to reduced ice cover. However, ice-strengthened vessels can also operate during spring, with potential impacts on seals and polar bears that are less vulnerable in September. The window of opportunity for navigation is growing as sea ice break-up happens earlier in the year and freeze-up occurs later. These changes also shift the times and places where marine mammals could be exposed to vessels.

The Arctic Ocean is covered with floating sea ice in winter, but the area of sea ice in late summer has decreased more than 30 percent since 1979. The Arctic Ocean is projected to be ice-free in summer within decades.

Planning for a navigable Arctic

Recent initiatives in the lower 48 states offer some models for anticipating and managing vessel-marine mammal interactions. One recent study showed that modeling could be used to predict blue whale locations off the California coast to help ships avoid key habitats. And since 2008, federal regulations have imposed seasonal and speed restrictions on ships in the North Atlantic to minimize threats to critically endangered right whales. These practical examples, along with our vulnerability ranking, could provide a foundation for similar steps to protect marine mammals in the Arctic.

The International Maritime Organization has already adopted a Polar Code, which was developed to promote safe ship travel in polar waters. It recommends identifying areas of ecological importance, but does not currently include direct strategies to designate important habitats or reduce vessel effects on marine mammals, although the organization has taken steps to protect marine habitat in the Bering Sea.

Even if nations take rigorous action to mitigate climate change, models predict that September Arctic sea ice will continue to decrease over the next 30 years. There is an opportunity now to plan for an increasingly accessible and rapidly changing Arctic, and to minimize risks to creatures that are found nowhere else on Earth.The Conversation

Donna Hauser, Research Assistant Professor, International Arctic Research Center, University of Alaska Fairbanks; Harry Stern, Principal Mathematician, Polar Science Center, University of Washington, and Kristin Laidre, Associate Professor of Aquatic and Fishery Sciences, University of Washington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids: What sea creature can attack and win over a blue whale?



File 20180815 2915 163gn3u.jpg?ixlib=rb 1.1
Blue whales are the largest creatures to have ever lived on Earth.
Shutterstock

Wally Franklin, Southern Cross University and Trish Franklin, Southern Cross University

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky! You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.


What sea creature can attack and win over a blue whale? – Drake, age 7, Sydney.


Hi Drake. That is an interesting question.

As you probably know, blue whales are the largest creatures to have ever lived on Earth – bigger than any dinosaur. They can grow up to 30 metres in length and weigh over 150 tonnes. This is very, very BIG. To give you an idea of how big a blue whale is, it’s the size of a Boeing 737 plane! Because of their size, power and speed, adult blue whales have virtually no natural ocean predators.

The only sea creature known to attack blue whales is the orca whale (scientific name: Orcinus orca) also known as the “killer whale”. They have been known to work in groups to attack blue whales.

However, there are very few reports of orcas actually killing blue whales. We know that orca whales interact with them because many blue whales carry scars from the teeth of orcas. But blue whales probably see orcas as more of a pest than a predator.

Orcas have sharp teeth.
Shutterstock



Read more:
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Blue whales can grow 30 metres in length and weigh over 150 tonnes.
Kurzon/Wikimedia Commons, CC BY-SA

The human threat

A much more serious problem for blue whales is humans. Humans have caused a lot of trouble for blue whales over the years.

One big problem is what we call “ship strikes”. This is when large ships collide with blue whales causing dreadful wounds and, in many cases, death.

Blue whales migrate freely across all the great oceans of the world to breed. They travel each year to the Antarctic in search of food. Global warming is a major future threat to their way of life. This is because rising sea temperatures and ocean acidification (which are caused by climate change) are likely to cause severe disruption to the production of their main food source, the very small crustacean we call “krill”.

Blue whales were the target of commercial whalers, mainly in Antarctica, between 1900 and the 1970s. During that time, over 330,000 blue whales were killed.

Fortunately – and only just in time – the International Whaling Commission banned commercial whaling in 1966. Blue whales are now a protected species and are recovering from the brink of extinction. People on whale watching trips at various locations around the world can see them, if they are lucky. The risk of whaling still exists in several countries, including Japan, Iceland and Norway. Many people in these countries are seeking to return to commercial whaling. Recently, whalers in Iceland killed a hybrid blue whale.

Blue whales can talk

One of the most interesting things about blue whales is that they use very low frequency sounds to communicate. Through this they can talk to each other over great distances. The low frequency sounds can pass through the earth, so it’s possible to record their songs and sounds from anywhere in the world.

In the 1960s, an American scientist called Chris Clark got permission to use the USA’s submarine listening system across the Atlantic Ocean to listen to blue whales. One day, he heard a blue whale calling from the far northeast Atlantic Ocean and realised another whale many thousands of miles away in the southwest Atlantic Ocean was answering it. Through their calls, he tracked them over the next few weeks moving towards each other. The two blue whales met and spent time together in the middle of the Atlantic. Then they separated and went on their way!

A pair of blue whales swims under the surface in Monterey Bay, California.
Shutterstock

It is important for all who are interested in the conservation and protection of these amazing creatures to remain vigilant and involved in making sure that they remain safe. Whales are part of the international heritage of all people of the Earth.




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Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au

* Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or

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Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

Wally Franklin, Researcher and co-director of the The Oceania Project, Southern Cross University and Trish Franklin, Researcher and co-director of The Oceania Project , Southern Cross University

This article was originally published on The Conversation. Read the original article.