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Fact #20
Steller sea lions are polygamous, where dominant males will mate with numerous females.

More facts...

 
Take the Animal Tracks Quiz and find out how your knowledge measures up!

Question 1:
In the last two decades, the western population of steller sea lions in Alaska has declined by what percentage?
10
20
40
80

 
Vancouver Aquarium Aquafacts - Gray Whales
Given that the Vancouver Aquarium has no grey whales in its care, it may be a bit of a mystery why they have an information page on these large mammals. But these folks are in the business of informing the general public about what the natural marine life of the area in which they live is all about, as much as anything else. So here you'll find a fairly thorough information page on the grey whale - detailing everything from what they eat to where they live. There's even a 'Did You Know' section. No pictures, but nicely presented, nonetheless.

 

ARE THERE TOO MANY GREY WHALES?

There are now more than 25,000 Pacific grey whales
There are now more than 25,000 Pacific grey whales
By: Steven Hunt - It's a question that would have been unthinkable only 60 or 70 years ago. Then again, that was a time when they were at the brink of extinction. Now at more than 25,000 with an astonishing annual rate of growth of 3.2 per cent, the question has begun to surface: are there now too many grey whales? It's not that they're imposing upon the livelihood of fishers along their migratory path from Baja, Mexico to Alaska and back again - they only eat crustaceans and small fish that live near the muddy bottom and they rarely eat at all while migrating. The question about whether there are too many has cropped up because an increasing number of carcasses have washed up on shores along the Pacific coast in the past few years.

In the past two years, the number of dead whales washing ashore has risen dramatically.
In the past two years, the number of dead whales washing ashore has risen dramatically.
Between 1990 and 1997, the number of dead grey whales along the coast of California ranged from 10 to 16. In 1998, it increased to 30 and by 1999 it was up to 47. The same thing has also been seen along the British Columbia coast. Last summer alone, more than a dozen grey whales were found washed up on the beaches of the lower BC coast. In fact, two years ago nearly three hundred dead grey whales were found along their entire migration route.

That number startled some people. Scientists, however, were not so quick to jump to conclusions. Because these animals feed very little during migration, it can be difficult interpreting the clues that have led to these animals' deaths since they have been malnourished and are more susceptible to disease. But Dr. Dave Duffus of the University of Victoria does think this is part of the equation. There simply isn't enough food to go around.

Mysids and other crustaceans and small fish make up the majority of the grey whales' diet
Mysids and other crustaceans and small fish make up the majority of the grey whales' diet
Since the grey whale population is doing so well, Duffus thinks that the rich waters off Alaska - their normal feeding grounds in summer - can't accommodate all of the whales. His hunch is supported by the fact that over 70 grey whales have been documented as feeding in BC waters for the summer, instead of going further north to Alaska. The reason? There's food off Vancouver Island that these whales are taking advantage of, namely crustaceans called mysids. But just because they're diversifying in the number of locations they feed at doesn't mean there's necessarily too many of them - even if the numbers in their deaths are up.

Click on the image for an @discovery.ca item on Juanita the grey whale who made Victoria, BC her new summer home.
Click on the image for an @discovery.ca item on Juanita the grey whale who made Victoria, BC her new summer home.
It's all part of the circle of life, as Duffus puts it. In the years after whaling was banned, grey whales went through a kind of baby boom, and today, those boomers are 30 and 40 years old. "The alarm about the dead grey whales is interesting," says Duffus, "because immediately people are thinking about ecological circumstances - things like El Nino and ocean change." But as Duffus points out, it's the baby boom effect at play. "We also have a lot of animals of a higher age. It's like the baby boomers who are at retirement age. And of course, they don't go to the retirement villa. They wash up on the beach."

As Duffus and his fellow researchers have noticed, the documented dead grey whales did not appear to have been suffering from any diseases, and besides, most of the animals that are washing ashore are up around where their life expectancy should be.

So the question about whether there are too many grey whales may be premature. It does appear some have chosen to not travel as far to their traditional feeding grounds. Whether that's because there is a dwindling food supply is not yet clear. As to why so many whale carcasses have washed ashore recently, for Duffus it appears to simply be a sign of the times for grey whales - a sign that their numbers are doing extremely well, and a sign that the first generations of whales that escaped near extinction over 30 years ago are finally passing on.


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Grey Whale
(Eschrictius robustus)
Habitat: migration patterns allow for two habitats: the summer feeding grounds from BC, north to the Bering Strait and the Arctic Ocean; and the breeding grounds off Baja, Mexico in the winter; they navigate close the shore and follow the contours of the sea floor.
Length: adults measure roughly 14 metres, on average
Weight: males and females can weigh as much as 30,000 kilograms
Appearance:grey whales have a sharply pointed bowed head, no dorsal fins and a series of knuckles or bumps along the midline of their lower back; as their name implies, they are a dark grey to black colour and have blotches of lighter colours due to barnacles; their tail flukes are not particularly large, given their size.
Behaviour: grey whales are often seen breaching, leaping into the air and splashing back into the water; it is thought that breaching helps them dislodge some of the parasites clinging to their skin; they are also the only baleen whale species that regularly feeds on bottom-dwelling animals.
Diet: small, shrimp-like creatures called amphipods are their mainstay, which live on the muddy ocean floor; they also eat small fish, herring eggs, tubeworms and mysids; a typical feeding day consists of 1,200 kilograms of sea food.
Life cycle: grey whales reach sexual maturity anywhere from 5 to 11 years old, or when they reach 11 to 12 metres in length; gestation lasts from 12 to 14 months.
Life span: a life expectancy of 50 to 60 years is not uncommon.

 

 
The Sun Bear
The Cheetah
The Grey Whale and Stellar Sea Lions
Urban Australian Animals
Grizzly Bears
Deadly Encounters
Rethinking Zoos
Threatened Birds
Reptiles
Sonoran Pronghorns
Petrels and Bobcats
African Penguins
Killer Whales


 

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