Pacific killer whales are dying — new research shows why



A female killer whale leaps from the water in Puget Sound near Seattle.
(AP Photo/Elaine Thompson)

Stephen Raverty, University of British Columbia and Joseph K. Gaydos, University of California, Davis

Killer whales are icons of the northeastern Pacific Ocean. They are intimately associated with the region’s natural history and First Nations communities. They are apex predators, with females living as long as 100 years old, and recognized a sentinels of ecosystem health — and some populations are currently threatened with extinction.

There are three major types of killer whales in the region: the “resident” populations that feed mainly on salmon, the “transients” that prey on other marine mammals like seals and sea lions, and the “offshores” that transit along the continental shelf, eating fish and sharks.

In the 1990s, an abrupt decline in the fish-eating southern resident population dropped to 75 whales from 98, prompting both Canada and the United States to list them as endangered.

A dead killer whale lies on her side in shallow water.
Emaciated female killer whale from Hawaii.
(NOAA/NMFS/PIRO), CC BY

Since then, southern resident killer whales, whose range extends from the waters off the southeast Alaska and the coast of British Columbia to California, have not recovered — only 74 remain today. Because killer whale strandings are rare, scientists have been uncertain about the causes of killer whale mortality and how additional deaths might be prevented in the future.

As a pathologist and wildlife veterinarian, and with the help of countless biologists and veterinarians, we have carried out in-depth investigations into why killer whales in this region strand and died. If we don’t know what is causing killer whale deaths, we are not able to prevent the ones that are human-caused.

We can do better

Human activities have been implicated in the decline and lack of recovery of the southern resident killer whale population, including ship noise and strikes, contaminants, reduced prey abundance and past capture of these animals for aquariums.

Only three per cent and 20 per cent of the northern and southern resident killer whales, respectively, that died between 1925 and 2011 were even found and available for a post-mortem exam. And in most cases, only cursory or incomplete post-mortem exams can be done, generating a limited amount of information.

To figure out why these killer whales are dying — and what it means for the health of individual animals and the population as a whole — we reviewed the post-mortem records of 53 animals that became stranded in the eastern Pacific Ocean and Hawaii between 2004 and 2013. We identified the cause of death in 22 animals, and gained important insight from nine other animals where the cause of death could not be determined.

Human-caused injuries were found in nearly every age group of whales, including adults, sub-adults and calves. Some had ingested fishing hooks, but evidence of blunt-force trauma, consistent with ship and propeller strikes, was more common.

A dead killer whale lies on a beach
The 18-year-old male southern resident killer whale, J34, stranded near Sechelt, B.C., on Dec. 21, 2016. Post-mortem examination suggested he died from trauma consistent with vessel strike.
(Paul Cottrell/Fisheries and Oceans Canada), Author provided

This is the first study to document the lesions and forensic evidence of lethal trauma from ship and propeller strikes.

In recent years governments have focused on limiting vessel noise and disturbance. This study reinforces the need for this, showing that in addition to noise and disturbance, vessel strikes are an important cause of death in killer whales.

Direct human impact

We also developed a body condition index to evaluate the animals’ nutritional health — were they eating enough salmon, for example — to see what role food might play in the sickness and death of stranded animals. Observations of free-ranging killer whales from boats and by unmanned aerial drones have documented sub-optimal body condition or generalized emaciation in many southern resident killer whales.

In this study, we found that longer and therefore older animals tend to have thicker blubber. Our study also found that those animals that died from blunt-force trauma had a better body condition — they were in good health before death. Those that died from infections or nutritional causes were more likely to be in worse body condition.

This new body condition index can help scientists better understand the health of killer whales, and gives us a tool to evaluate their health regardless of their age, reproductive status and health condition.

Our team, working with numerous collaborators including the National Marine Mammal Foundation, is building a health database of the killer whales living in the northeastern Pacific Ocean so that their health can be tracked over time. This centralized database will let stranding response programs, regional and national government agencies and First Nations communities collaborate with field biologists, research scientists and veterinarians.

Ultimately, the information about the health of these killer whales must be conveyed to the public and policy-makers to ensure that the appropriate legislation is enacted to reverse the downward trend in the health and survival of these killer whales. We should now be able to assess future efforts and gain a better understanding of the impact of ongoing human activities, such as fishing, boating and shipping.The Conversation

Stephen Raverty, Adjunct professor, Veterinary Pathology, University of British Columbia and Joseph K. Gaydos, Wildlife Veterinarian and Science Director, The SeaDoc Society, University of California, Davis

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.




Read more:
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.




Read more:
Curious Kids: how do creatures living in the deep sea stay alive given the pressure?


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.

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:
Curious Kids: Why do sea otters clap?


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.




Read more:
Curious Kids: How do plastic bags harm our environment and sea life?


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

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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.

Indonesia: Killer Whale Strikes Back


The link below is to an article reporting on how a whaling operation came unstuck as a harpooned Killer Whale sunk a whaling vessel.

For more visit:
http://www.treehugger.com/natural-sciences/harpooned-killer-whale-drags-down-boat-indonesia.html