Ask
a Marine Scientist:
answers to Mammals questions!
Choose one of the following:
- Suborder
Odontoceti -Toothed Whales (Dolphins, Porpoises,
Killer & Sperm Whales)
- Suborder Mysticeti -
Baleen Whales (Gray Whales, Blue Whales, Humpback
Whales)
- General Whale Biology -
Whale Biology, Whale Populations, Whales & Humans
- Seals, Sea Lions, Walrus, Manatees,
and Sea Otters
ASK
A SCIENTIST: ANSWERS TO QUESTIONS
General Whale Biology
Index to Questions
WHALE BIOLOGY
WHALE POPULATIONS
WHALES & HUMANS
WHALE BIOLOGY
 Whale
Sizes
Q: How big is a narwhale and
beluga whale?
A: An adult Beluga whale can
weigh between 0.4-1.5 tons while an adult Narwhal can weigh between
0.8-1.6 tons.
Why
are whales big? (received from Ryan in Philadelphia,
PA)
Q. Why do whales get as big as they do?
A. This is a great question! Why do (or did, in the case of dinosaurs) animals
grow so large?
Even dinosaurs could not reach the same size as the largest of all animals,
the blue whale. Only a medium such as water could support an animal of such
enormous size. So water buoyancy has allowed whales to attain their enormous
sizes, but why has it happened?
Having a large body size is actually a great way of generating and holding
heat. This is particularly important in the ocean where the cold water can
zap away body heat up to 20 times faster than on land. Ecologist Adrian Forsyth
writes that "a single blue whale is as massive and burns as much
energy as the entire human population of a 2,000 resident North American town." If
this whale lived on land, over-heating would be a serious problem since it
would have a small surface area relative to its body size (animals generate
heat internally and lose it across their body surface). But since
it lives in water, whales quickly lose the large amounts of heat that their
bodies generate.
As an animal increases in size, there is proportionately less skin area exposed
relative to their total body mass, and therefore, less heat loss to the environment.
You can use sugar cubes to illustrate this statement. In one sugar cube, the
surface area is 6 square centimetres and the volume is 1 cubic centimetre.
Therefore the surface area to volume ratio is 6:1. If you make a new cube using
8 sugar cubes, the surface area to volume ratio is now 24:8 or 3:1. So proportionately,
there is less surface area exposed in the large cube structure. If these cubes
were animals (say a mouse vs. an elephant) it would be harder for the smaller
animal to keep warm, due to the increased heat loss across the body surface.
Answered by Adrienne Mason
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Weighing
whales (received from Kelley in California)
Question: How do you weigh whales?
A. An interesting question,
given that whales are the largest animals on earth, and live
in the water, where it is difficult to weigh things.
Aquaria that keep whales in
captivity often will weigh the smaller animals (dolphins and
baby whales) by lifting them out of the water on a sling, and
taking their weights with a large spring type balance. With baby
whales born in captivity, it is important to track their weight,
to make sure that they are getting enough milk from their mothers.
But what about huge whales
like the Blue Whale you ask?
In the old days of whaling, all of the various parts of a captured whale were
weighed. The weights of all of the parts of the whale were added together to
obtain the weight of the whole whale. This information may still be obtained
from autopsies on dead whales that have washed ashore. From looking at many
measurements, scientists were able to develop a formula for each species that
can estimate a whales weight from its length.
Today, scientists simply have to estimate a whales length, apply the calculations,
and obtain a good estimate of the whales weight.
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Retia
Mirabilia (received from Ron in Phoenix)
Question: Could you define "Retia Mirabilia" ?
Retia
mirabilia are blood vessels that are found in dolphins, whales,
dugongs, and manatees,
as well as in non-marine mammals such as armadillos, anteaters
and some rodents. The name translates literally to mean "wonderful
net".
In marine mammals, these nets
of blood vessels may function to protect the animals from the
effects of bubbles forming in the blood after they surface from
dives.
Also, blood from the retia
mirabilia in marine mammals feeds the brain tissues. In this
way, the animals are ensured of a constant blood supply to the
brain while diving - otherwise the water pressure would squeeze
the carotid arteries, and prevent blood from going to the brain.
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Snoring
Whales (received from Chikako Harada in Tokyo)
Q: I want to know whether marine mammals snore while they are sleeping.
An interesting question.
Why do humans (and many other animals) snore in the first place? The noise
of air passing by the epiglottis is often the cause of snoring, especially
when the position of the head is tipped back. Normally, the function of the
epiglottis is to cover the windpipe while swallowing something, in order to
prevent the food or liquid from going down into the lungs. (Have you ever swallowed
something the wrong way, and coughed and choked?).
It is certainly possible that seals and sea lions snore when they are sleeping.
One amazing adaptation of whales, is that they no longer need to have an epiglottis.
This is because the functions of breathing and swallowing have been physically
separated in whales. The blowholes and nasal passages are not at all connected
with their esophagus and stomach. Whales never have to worry about choking
on their food! Because they have no epiglottis, it is unlikely that whales
snore, although they do rest at the surface when they sleep.
A fisherman friends of ours swears, however, that when he was a small boy on
the fishing boats at sea, he could hear humpback whales bumping up against
the boat at night, and their breathing was very loud! Certainly the normal
exhalation of breath through a whale's blowhole can be quite a noisy thing!
More Information on snoring marine mammals from Adrienne Mason!
Technically, a snore is produced by vibrations of the soft palate, usually
caused by any condition that hinders breathing through the nose. Snoring is
more common when a person (or animal?!) is on their back. Pinnipeds (seals
and sea lions) do snore"you can hear them snorting, chortling and yes,
probably snoring, at their haul-outs on land. These animals do rest and sleep
in many positions so a true snore is probably more likely. As far as snoring
whales go, I consulted Dr. John Ford who is a killer whale researcher. He says
that he has heard whales "snoring""bubbling out their blowholes"as
they rest as the surface. Whether this is technically a true snore, as defined
above, I'm not sure. Check this site in another week or so, to see if I have
more to add.
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Communication
in Whales (received from Dan in New Hampshire)
Q: Hi, my name is Dan, and I have 1 question for you and that is,
Do whales communicate, why, and how??
I have to print out this info for my niece, for her school project.
So any site that could give me this info would be greatly
appreciated. Thanks Dan.
A: Have you checked out the information on this site regarding communication
in Killer
Whales? If not, it is a good place to start. Many species of both baleen
and toothed whales communicate by using sounds that may travel great distances
underwater.
Humpback Whales, Megaptera novaeangliae, have elaborate "songs" that
last from 6 to 35 minutes before being repeated. The whales may sing continuously
for up to 22 hours! Each individual Humpback has its own vocal signature, and
therefore may be recognized by its song. In addition, each distinct population
of Humpbacks (e.g. North Pacific, North Atlantic) sings its own particular
type of song. These populations subtly change their songs from year to year,
all individuals within the population changing their songs in the same way.
It seems likely that the humpback song functions for mate attraction, since
the songs are sung on the breeding grounds.
Killer Whales (Orcinus orca) also communicate by making noises. Again,
individual whales have distinct calls, and can be recognized by them. An important
function of the sounds is probably one of identification. Through the whales
sounds, the identity, location, sex, and status may be recognized by other
whales. Since different pods of Killer Whales may have very different "dialects",
the sounds may also identify which pod a whale is from. This may be very important
in these whales, which have very distinct matriarchal groupings, and they do
not usually move from pod to pod.
The communication that has been shown to occur in whales is relatively simple,
similar to the communication that many other animals engage in - identifying
individuals and communicating breeding status. Whether or not whales and dolphins
are able to communicate more complex ideas and thoughts has never been adequately
shown.
Another good whale site that you might try is WhaleNet.
It has a lot of information about marine mammals.
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Marine
mammals and water consumption - Received from Burack
in Jackson, New Hampshire.
Q: Do dolphins, whales
or other sea mammals drink seawater ? If so, do their kidneys
concentrate urine more effectively than mammals that drink
freshwater.
A: It is very likely that
marine mammals incidentally ingest sea water with their food,
although there is inadequate information about the exact amount
taken in. Baleen whales and some pinnipeds feed on crustacean
organisms, which have a high salt content compared to fishes.
Since whales do not possess sweat glands, they must eliminate
excess salt from the body via urine production. The kidneys of
whales and seals are able to produce a urine which is more concentrated
than seawater; whale urine is reported to have a chloride concentration
of 820 mmol/L, while seawater is approximately 535 mmol Cl/L.
Whale kidneys have numerous
divisions which increase surface area, allowing a greater removal
of salts from the blood than human kidneys. If a human were to
drink 1 L of sea water, there would be a net water loss of approximately
350 mL. This is why, if you're stranded at sea and severely dehydrated,
you should not drink sea water as it will only worsen the situation.
On the other hand, whales would show a net gain of 350 mL of
pure water after ingesting 1 L of sea water, due to their powerful
kidneys. However, it is believed that whales and pinnipeds get
adequate water from their diet, and do not have to purposely
ingest sea water.
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How
Whales Drink - Received from Jewls in California
Q: How do gray whales get
fresh water if they live in an ocean full of salt water?
A: Gray whales and all other
whales get freshwater (drinking water) from their food. They
will also get some of their drinking water from ocean water they
swallow. The kidneys of whales extremely well developed and are
able, to some extent, filter out the salt from the water.
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Whale's
Blowhole - Received from Andrea Allen in Middle Creek
School, West Virginia
Q: Why do whales have A
BLOWHOLE AND WHY DO THEY BLOW OUT OF IT?
A: All cetaceans (whales,
dolphins and porpoises) breathe only through their blowholes,
which are situated on or near the top of the head. Remember that
whales, like humans are mammals and must breathe air not water.
Blowholes are similar to nostrils in other mammals, serving as
openings to the respiratory passages. Baleen whales (e.g. humpback
and gray whales) have two blowholes side-by-side, while toothed
whales (e.g. dolphins and sperm whales) have only one blowhole.
Cetaceans cannot breathe through their mouths, because the trachea
(air passage) and esophagus (food passage) are completely separate.
The trachea connects only to the blowhole. Therefore whales blow
air out of their blowholes. The water that you see sprayed into
the air is actually the water on the whales back when it comes
to surface. Whales must blow this water away from their blowhole
with air so that they can take in a breath of air, not water,
through their blowhole.
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Whale
predators - Received from Kim in Ohio
Q: Can you tell me if there
are predators for gray whales, killer whales, sperm whales,
and bottlenose whales?
A: Killer
whales have no known predators, unless you count mortalities
from specimen capture for aquariums or the occasional great white
shark. Killer whales make better predators than prey, and hunt
at least 25 whale and dolphin species, seals, sea lions, squids,
birds, sea turtles, and fish.
The main predator of gray
whales is killer whales. Gray whales often have scars from killer
whale attacks, if they are lucky enough to survive. One eye-witness
report from a Japanese whaler in 1911 recounts how a pod of killer
whales attacked a gray that he was hunting. Apparently, upon
seeing the approaching hunters, the gray rolled belly up. A killer
whale swam right into the mouth of its prey and started ripping
out chunks of tongue while its pod mates tore into the stomach
and fins. Other gray whale predators are humans and some large
sharks that attack gray whale calves.
Sperm whales used to be a
major catch of whalers, and are still hunted by those countries
where whaling is legal. The only other predators are large sharks
or killer whales on unprotected calves.
Bottle nose whales used to
be extensively hunted by people because they would approach whaling
ship on their own, making them easy prey. Killer whales are also
a major predator on bottle nosed whales.
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Marine
Mammal Dental Care (received from Mary in New York)
Question: What type of dental care is provided for marine mammals in captivity
or in the wild? What training is available in this area? What role can a dentist
play in marine mammology?
A
You may wish to check out a paper that was published in Zoo Biology
9(4) pp. 325-330 by
Mark Graham and Pierre Dow. The title is "Dental Care for
a Captive Killer Whale, Orcinus orca." This is a brief note
on one type of care on marine mammals that has taken place at
the Vancouver Aquarium.. There is no specific training for marine
mammals but there are veterinary dentists who are specially trained
as dentists in veterinary school. Wild marine mammals don't really
receive any dental care, in the same way that wild terrestrial
mammals don't receive dental care. Come to think of it, it would
be easier to do dental care on a wild siberian tiger than on
a whale!
(Answered by Treva Ricou, Vancouver Aquarium)
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Whale
pictures - Received from Barb in Westlock.
Q: Where can I find full
page pictures of whales?
Try the following web site:
Cetacean
Picture Gallery
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Cetacean
diseases - Received from Kristen in Findlay, Ohio.
Q: I'm looking for information
of cetacean nutritional diseases. What are some of the most
common nutritional related problems that occur with cetaceans?
Are there specific diseases related to Nutrition??
Unfortunately there is not
a lot of knowledge about the role of disease in wild cetacean
populations. Most of the information collected has focused on
the type and effects of internal parasites, which doesn't sound
like what you're looking for. The following reference may be
of use to you:
Howard, E.D. (ed.) 1983. Pathobiology
of Marine Mammal Diseases, Vols. I and II. CRC Press, Boca Raton,
Fla.
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Whale
bacteria - Received from Ernani.
Q: I'm thinking about the
gut microflora of whales. They have the same type of bacterias,
like other mammals: Bacteroides, Escherchia coli, Clostridium
or they have specific salt-tolerant bacterias in their gut,
like Vibrios?
A: It
seems that there has been much work done on the digestive system
of minke whales (Balaenoptera acutorostrata). This baleen
whale has a stomach consisting of four compartments, similar
to a ruminant such as a cow. These chambers are as follows: non-glandular
forestomach, glandular fundic chamber, connecting chamber and
pyloric chamber. High populations of anaerobic bacteria were
found in the forestomach fluid, and it has been concluded that
minke whales utilize the prey that they eat by microbial digestion.
The bacterial strains most common in the forestomach include Lactobacillus spp.
(19.7%), Streptococcus spp. (35.9%), and Ruminococcus spp.
(12.8%). All strains were found to be strictly anaerobic, and
over 60% were cocci. It was determined that this forestomach
microbiota was indigenous to the whale, and did not originate
from the prey species which it was digesting.
For more information on this
subject, head down to your college/university library to access
databases such as Biological Abstracts and Aquatic Sciences and
Fisheries Abstracts (ASFA).
References:
Mathiesen, SD, Aagnes, TH,
Sormo, W, Nordoy, ES, Blix, AS and Olsen, MA. 1995. Digestive
physiology of minke whales. In Whales, Seals, Fish and
Man. Proceedings of the International Symposium on the Biology
of Marine Mammals in the North East Atlantic held in Tromso,
Norway, 29 November-December 1, 1994., Elsevier Science B.V.,
Amsterdam (Netherlands), 1995, 351, Dev. Mar. Biol., vol. 4.
Olsen, MA, Aagnes, TH and
Mathiesen, SD. 1994. Digestion of herring by indigenous bacteria
in the minke whale. Applied and Environmental Microbiology, vol.
60, no. 12, pp. 4445-4455
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Why
do whales have hair? (received from Cody in California)
Q. Why do baby whales have hair on them when they are first born?
A. Cetaceans (whales, dolphins and porpoises) are mammals. Mammals breathe
air, give birth to live young which they suckle and care for, and are covered
in hair or fur. This definition becomes a little confusing with cetaceans because
when they are born they are hairless except for a few bristles that are usually
found on their head. Most cetaceans will lose these hairs within a few days.
Some, such as humpbacks, keep these hairs and they probably serve a sensory
function (something like a cat's whiskers). Cetaceans have descended from land
mammals that were covered in fur so the few hairs that remain are linked to
their terrestrial ancestors of thousands of years ago.
Answered by Adrienne Mason
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Whale
Hair - Received from Ashley Deblaey in Phoenix,
Arizona
Q: Do whales, killer whales,
and bottle-nosed dolphins have any hair at all on their bodies???
AS for whales, I have found that some books say yes and some
say no. I have not found anything for killer whales and dolphins.
Thank you.
A: Killer whales and bottlenose
dolphins are mammals and one of the features of a mammal is that
they are covered in hair or fur. Well killer whales and bottlenose
dolphins do not have hair covering their body, they may have
a couple chin whiskers, but nothing more. In fact grey whales
have nodules on their nose that in the past was where hair follicles
would attach, but have evolved into sensory nodules. In the past
whales and dolphins had hair but through evolution they lost
the hair because it slowed them down when they were swimming.
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Whale
Lifespans - Received from Sueli
Q: How long does a whale
live if it doesn't get caught?
A: There are also many different
species of whales that are all very different. Subsequently,
the different species have slightly different lifespans. The
average lifespan for a whale is approximately 50-70 years, roughly
the same as for humans.
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Whale
Scat -
received from Michael in Atlanta, Georgia.
Q: I was wondering how a whale
goes to the bathroom, where it goes and how big it is. My friend
scared me and said it was as big as a person...
A: This is a very interesting
question...
In fact whale scat is known to be a cloudy liquid, often containing bone and
shell remnants of the whale's prey. It is released by a whale as it dives down
from the water's surface.
Whale and other marine mammal scat is useful to marine biologists who want
to find out what constitutes its diet. The solid parts of the scat are scooped
up with fine net or a bucket, dried out, and then analysed.
I have not seen a whale go to the bathroom, but a friend of mine was out collecting
grey whale scat just last week for analysis of it's diet. He says it wasn't
as big as a person, and it dissipated quickly it the water. So no worries.
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Nursing
baby whales (received from Wanda in Nova Scotia)
Question: How long does a baby whale nurse?
A. It really depends on what
kind of whale you're talking about! Among the baleen whales,
nursing periods range from 4 months for the Minke Whale to an
estimate of 12 months for the Right Whale.The toothed whales
and dolphins nurse for longer periods of time, in general. Harbour
porpoises may nurse for 8 months, while the Beluga whale may
nurse for 20-24 months. There is even evidence that some juvenile
whales may continue to suckle for many years.
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Sexing
Whales - Received from Pam Allen in Granbury, Texas
Q: How do you tell if a
whale is a male or female?
A: To tell a male from a female
whale you must look closely at the underside of the whale. Both
males and females have a genital and anal slits, but in males,
the two slits are further apart. Females also have two small
mammary (milk) slits on either side of their genital slit. When
the mother whales are feeding their young their nipples will
stick out of the mammary slits.
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Stranded
Marine Animals - Received from Jennifer in
New Zealand
Q: What
causes sea animals to swim towards land and get stranded?
A.
There are a variety of reasons why an animal can get stranded.
Some like to feed near
shore (i.e. grey whales), and by accident they might get beached
during the feeding process. It is also common for injured animals
to beach themselves. Injured animals get tired, and may not be
able to swim. It makes sense that they would come inshore to
shallow waters to rest & avoid drowning. Dead animals are
often found on the beach, where they wash ashore with the tides.
Some animals beach themselves for unknown reasons.
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Whale
Communication - recieved
from Katherine in Australia
Q: I
am doing a project on whales and i need to know what pitch/frequency
fo whales communicate and lure prey at?
A: Acoustics is a major area
of study for whale researchers. Sound is exceptionally important
to marine mammals living in the ocean (a very noisy place). And,
you are correct in thinking that whales use different frequencies
when they are producing sounds for different purposes. Whales
use echolocation clicks to locate prey. These are short bursts
of soundwaves that bounce off objects and return back to the
whale and allow them to find prey. On the other hand, whales
use calls, whistles and songs when communicating and socializing
with other whales. Different kinds of whales will all make sounds
in different frequency ranges. Here are some examples:
The fin and blue whales make the lowest frequency echolocation
clicks. At 14-20Hz these "noises" were first detected
as rumbles on seismographs (earthquake detectors).
Odontocetes (the toothed whales like killer whales and belugas)
are normally thought of as the most vocal. Odontocete sonar (echolocation
clicks) range
from 10Hz to 200kHz (a kiloHertz is equal to 1000Hz) and their social calls
range from 200Hz to 20kHz. Odontocetes such as sperm whales are also suspected
of using a "big bang" technique for hunting. They emit extremely
high frequency, short bursts of sound that stun their prey.
Acoustics is a fascinating science. You should take a look at ORCA FM which
is live recordings of killer whales off British Columbia. This site and the
Orca-Live site have some sound bytes so you can hear what various
whales sound like. Enjoy!
Orca Live
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Deep
Dives - received
on from Jeff in Washinton
Q; I am trying to do a
paper on how some marine mammals can dive so deep with the
water pressure involved. and how this effects the body.
A: The diving physiology
of marine mammals is fascinating. It is a complex and interesting
combination of adaptations that allow them to deal with low
temperatures, high water pressure and prolonged dives without
oxygen.
These adaptations include:
-Bradycardia: a lowered heart rate -in seals as low as 4 beats per minute (so
called diving while dead)
- Vasoconstriction in peripheral tissues
-lobed lungs for higher oxygen retention
-elastic and muscular lungs and diapragm
-cartilagenous trachea (pinniped hold air there and not in lungs, lungs are
able to fully collapse and no air remains during dive)
-rete mirabile (excess oxygen stores in peripheral blood system.
-higher hematocrit levels (higher oxygen concentration in blood)
-aortic arch that is enlarged to control blood pressure that leaves heart
Although these all seem mostly related to oxygen and not pressure, keeping
oxygen in their blood (not in their lungs as air which contains nitrogen) is
how marine mammals prevent high water pressure bubbling nitrogen into their
blood (the so called bends). This process cannot be explained here in the time
I have. There are many many scientific journal articles dedicated to this physiology.
You need to go to your university's library and do an abstract search for more
info.
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Longest
living marine mammal -
received from the Hetrick Family
Q: Would you be able to tell
us what mammal lives to be 200 years old?
A: You have acutally asked
a very intriguing question. Until very recently, elephants (which
live to be 50-70 years) were thought to be the oldest living
mammals. But, now researchers think that the bowhead whale may
very well live to be over 200 years old. What is intriguing is
the way the they discovered this. Whales are generally aged by
rings in their bony ear plugs. But bowhead whales do not have
these ear plugs and so they were difficult to age. Not too long
ago, Inuit hunters in the Arctic (who have been hunting the bowhead
for hundreds of years) were cutting up a bowhead they had harpooned
and found embedded deep in the blubber an ivory arrowhead. These
ancient harpoon points were found in numerous whales and were
dated to 130-200 years old. This means the whales are at least
that old. This was confirmed by chemical analysis of bowhead
eye lenses. Most whales were at least over 100 years old and
some may be over 200 years. What is most astounding is that all
these whales were killed by hunters. So who knows how old they
might have gotten if they had not been harpooned??!
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WHALE
POPULATIONS
Number
of marine mammals in the world (received from Melissa
in California)
Q: I am doing a biology project and my project is how many Marine Mammals live
in the Ocean, if you know of any could you please send the information.
A. We didn't want to just
give you a simple number, so we've broken the numbers of marine
mammals down by order, suborder, family and subfamily. Not that
not all scientists agree on the exact numbers of species in each
group, particularly in the suborder Odontoceti. Some scientists
split a group of similar animals into two or more species, while
others lump them together into a single species (for example,
Spotted Dolphins - one or four different species??)
- Order Cetacea
- Suborder Odontoceti (Toothed
Whales) 68
- Suborder Mysticeti (Baleen Whales) 11
- Order Carnivora
- Suborder Pinnipedia
- Family Phocidae (True Seals)
- Subfamily Monochinae (Southern Phocids) 8
- Subfamily Phocinae (Northern Phocids) 10
- Family Otariidae
- Subfamily Otariinae (Sea Lions) 5
- Subfamily Arctocephalinae (Fur Seals) 9
- Family Odobenidae (Walrus) 1
- Suborder Fissipeda
- Family Mustelidae (Sea Otter) 1
- Order Sirenia (Manatees and Dugong) 4
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Whale
Population Levels (received from Joan in Illinois)
Q: I need present day world populations for whales. My 6th grade gifted class
is studying oceanography..and importance of the oceans to the future of our
world. We also need to know what countries continue whaling and the numbers
killed.
Thank you
Very recent population levels for most whales can be fairly difficult to obtain.
According to The book, The Natural History of Whales and Dolphins, by Peter
G.H.Evans, 1990, Facts on File, New York, some population estimates are:
Sperm Whale: 2,000,000
Bowhead Whale 3,000 - 5,000
Northern Right Whale 400 - 1000
Gray Whale 17,000-18,000
Humpback Whale: 10,000
Blue Whale 14,000
Fin Whale 120,000
Sei Whale 54,000
Minke Whale 505,000
Orca Not well known - may be 160,000 in Antarctica. See Vancouver Aquarium's killer
whale page for British Columbia population estimates.
This book also has population
estimates for the many other species of dolphins and whales.
Check out the Vancouver Aquarium page on Beluga
Whales for
more information.
There is an interesting web site you may wish to check out by the High
North Alliance in Norway. They are a pro-whale hunting organization that
gives some facts and figures about whaling.
According to them, some population estimates are:
Blue Whale 7500-15,000 (1988)
Gray Whale 21,000 - 23,000 (1994)
Minke Whale 900,000 (IWC, 1994)
Sperm Whale 1,500,000 (1988)
Fin Whale 105,000 - 122,000 (1988)
Humpback Whale (This web site contains an inaccurate number for humpback whales.
It appears to be a typo)
Norway and Japan are the only countries that still officially engage in whale
hunts. Norway has a limited commercial hunt that took the following numbers
of Minke Whales:
1993: 296
1994: 314
1995: 232
These numbers are taken from the High North Alliance site in Norway
- In the 1992/93 season, Japan took 330 Minke Whales in Antarctic waters.
- In 1992/93, aboriginal catches were: Denmark (22 fin, 114 minke, and 1 other),
St. Vincent &
The Grenadines (2 humpback - 1 lost), and USA (50 bowhead whales - 12 lost).
- There may be other countries that have aboriginal catches but they are not
members of the International Whaling Commission. These Japanese and Aboriginal
numbers are from the Forty-fourth report of the International Whaling Commission.
Cambridge: International Whaling Commission, 1994
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Detailed
Whale population numbers (received from Dan and Brad
in Mill Bay, B.C.)
Question: Thank you for pointing us to info on populations of the right, sperm
and humpback whales. we were wondering if you had more detailed numbers. We
would like to show using a map and graphs the populations broken down by the
different oceans. Thank you.
A. Detailed data on whale
distributions are difficult to obtain. Although whales are a
very popular topic, there is not much money available for marine
mammal research, particularly for whales that inhabit mid-ocean
areas that are difficult and expensive to reach. here are some
numbers that we were able to confirm:
Northern Right Whale (Eubalaena
glacialis) 200-500 in North Pacific, 200-500 in North Atlantic
Southern Right Whale (Eubalaena
australis) estimated at 3,000 - 5,000
Sperm Whale (Physeter macrocephalus)
found around the world, and travel great distances. Separate
populations may exist, but we have no data on separate population
numbers. World population approximately 2,000,000
Humpback Whale (Megaptera
novaeangliae) 7,000 in Northern Hemisphere - mainly in
North Atlantic) and 3,000 in Southern Oceans.
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Are
Whales Becoming Extinct? (received from Matthew
in the Midwest)
Q: Why are the whales becoming extinct and what can we do to help them?
A. We're glad to be able to give you some good news, Matthew. The
whales of the world are not becoming extinct. In fact, no whales
have become extinct
in historical times, and there are only a few species of marine mammals that
currently have low populations and could be said to be "in trouble".
The Bowhead Whale, Balaena mysticetus was hunted quite extensively,
and now exists in Arctic waters in numbers of about 3,000 to 5,000 individuals.
The Northern Right Whale, Eubalaena glacialis exists in even smaller
numbers - about 400 - 1000 individuals. This whale was very easy to hunt (it
was the "right" whale to catch), and the numbers were greatly affected
by hunting. Populations of other whale species are in much better shape. In
fact, the Gray Whale, Eschrichtius robustus, was recently taken off
of the United States endangered species list, because it has made such a remarkable
recovery. Population estimates for the Gray Whale put it at about 21,000 -
24,000 individuals, around the same numbers as before commercial whaling.
You can still do things to help whales, even in the Midwest. Education is a
powerful tool; learn as much as you can about whales, and tell all of your
friends. The more we know about whales, the more we can see how important it
is to continue to protect them. Pollution is a major problem in the oceans
- it affects all marine life from plankton to whales. Don't forget that everything
that goes down your drain or down the sewer will eventually end up in the ocean.
You can make sure that your local community is doing everything possible to
keep the water clean.
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Whale
origins - received
from Emi in New York
Q: Is there any evidence that
whales used to live on the land?
A: Ancestors of present-day
whales were hoofed, dog-like animals called Mesonyx. These animals
were thought to eventually take to the water, and started spending
more time in the ocean, and less time on land. Some present-day
whales even have small, vestigial (non-functional) leg bones.
The most common ancestor to whales today are ungulates, such
as cows.
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WHALES & HUMANS
Human
Impacts on Whales (received from Lisa in Calgary,
AB)
Q: Please send me info about human factors affecting the whale
populations and what is being done to "save the whales".
I need this info A.S.A.P. Thanks!!!
A. One of the biggest impacts on the world's whale populations
was certainly the shore based and factory ship whaling over
the past century. This is the
period when populations of Humpback, Blue, Fin and Sei whales, among others,
where decimated. The numbers of these four species dropped precipitously from
1900 to 1980. An attempt to regulate whaling activities internationally was
made in 1946, with the establishment of the international whaling commission.
In Canada, all whaling was stopped in 1972, and in 1982, the Cetacean Protection
Regulations came into effect. Most other countries, including those that formerly
hunted whales, have also stopped all whaling. Currently, only Norway and Japan
continue to hunt whales. Most of the whales hunted today are Minke whales,
taken by "scientific" whaling ships. There is continued pressure
on both Norway and Japan to stop killing these whales.
Another problem for some species of whales and dolphins is the pollution of
their environment. See the question and answer about Belugas on the OceanLink
web site for more details!
On the bright side, some species of whales have done very well since humans
have stopped hunting them. Gray whale, whose populations where once reduced
to very low numbers, have recently been removed from the U.S. endangered species
list, as their numbers have returned to near historic levels.
You should be able to find out more details about whales and whaling either
in your school's library, or certainly in the Calgary library.
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International
Whaling Commission
Q: What are some accomplishments of the I.W.C international whaling commission
A. In the fall of 1946, The
International Convention for the Regulation of Whaling was adopted
by several whaling nations. This Convention established the International
Whaling Commission (IWC) The primary task of the IWC was to regulate
the whaling industry in such a way as to preserve the stocks
of undepleted species and permit the increase in numbers of those
already depleted. They set quotas on the numbers of whales to
be caught, but the regulations did little to stop the decline
in whale numbers. Blue whale numbers crashed in the 1950's, followed
by Fin Whales in the early 1960's and Sei Whales in the late
1960's. The methods used to set quotas were questionable, and
member nations often did not follow the regulations.
In the late 1970's and early
1980's, there were repeated calls at IWC meetings for a complete
ban on commercial whaling. In 1981, Canada withdrew from membership
in the IWC, as there had been a ban on commercial whaling in
Canada since 1972. Finally, in 1982, a majority voted in favour
of a ban, which came into effect in 1986.
You
might think that this was the end of whaling, but unfortunately,
the IWC has no control
over its members. Norway and Japan still engage in commercial
whaling, although they say that they are catching whales for "scientific" purposes.
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Marine
Mammals and food sources (received from Kevin in Edmonton)
Question: What do marine mammals do when their main food resource becomes depleted?
What kinds of problems do marine mammals cause humans and vice versa?Thanks
you for answering my questions.
A. Like any other animal,
if a food resource is depleted, they have a limited number of
choices:
They may migrate to another area where there is more food.
They could switch to another type of food resource (some animals are very flexible
and are able to do this. Others are unable to switch)
They could simply die out in the area where there is no food.
Humans have certainly caused
problems for marine mammals. We have hunted them - in some cases
reducing their numbers to a small fraction of what they once
were. In some cases, we have accidentally captured them in fishing
gear and killed them too. In the case of the Beluga whales of
the St. Lawrence, we have polluted their environment, and made
it difficult for them to reproduce.
I can't think of any problem
that marine mammals have caused humans!
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Whales
and Lobster Traps
Q: Why do some people think lobster trap lines entangle whales.
A. There has been lots of research done on the problem of whales colliding
with fixed fishing gear, as this is quite an important topic. The problem is
particularly seen among young humpback whales on the East Coast, when they
move inshore to feed on small fish such as capelin. The protrusions and barnacles
on the Humpback's skin may make it more prone to getting stuck in fishing nets.
Cod traps, gill nets and salmon nets were the most likely types of fishing
gear to entangle whales and other marine life in a study in Newfoundland in
1983. Since a lobster trap is connected to the float on the surface by a single
line, it is not as likely that these would pose an entanglement danger to whales,
unless there were a lot of traps in a relatively small area, or if the lines
on the traps were reinforced with steel cable.
Whales are particularly harmed by accidental capture in nets, since they take
a relatively long time to reproduce, and their populations do not increase
quickly. The loss of many animals accidentally can be very harmful to a population
already reduced by commercial whaling in the past.
More information on this topic may be found in:
Horwood, Harold. 1984. Setting free the whales. International Wildlife 14 (1):
4-11
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Effects
of Echolocation on Humans - Received from Mrs. Dello
Russo's class in Cambridge
Q: If a human were to be
in the way of the click train from a sperm whale, which we
think is strong enough to stun a giant squid, what would the
effect be?
A: For
this one I have a story from an underwater photographer who was
filming in the waters off the coast of Vancouver Island. He was
minding his own business when he suddenly felt a burst of pressure
in his chest. He thought it was a bit odd, but kept on filming
whatever it was he was filming. A few seconds later, he felt
a quick series of painful bursts. He looked around, and seeing
nothing, thought he was having a heart attack. The third time
it happened, he saw a killer whale swimming straight for him
out of the murky water. Once the whale saw he wasn't a seal,
it veered off and swam away. Now if it feels like a heart attack
when a killer whale sounds you, I'd imagine a full force click
train from a sperm whale would be lethal.
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Whale/human
evolution - Received from Mrs. Dello Russo's class in
Cambridge, MA
Q: Which kind of whale
is more closely related to humans in the evolutionary chain,
baleen or toothed?
A: Imagine
the evolution of life as a bush that starts with few branches
and grows into many. The branches of life that lead to whales
and humans diverged in the late Jurassic. In fact, the group
that eventually became whales also diverged into manatees, elephants,
and hoofed mammals. Whales differentiated into toothed and baleen
after they diverged from the branch that became humans (as well
as bats, rodents, sloths, anteaters, and carnivores). Therefore,
all whales are equally related to humans.
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Whale
and dolphin protection
Q: Why doesn't
the government try harder to protect whales and dolphins?
A: The government
is meant to be a reflection of society, so what is important
to society is important to the government. If the government
doesn't value whales and dolphins, that means there are probably
people in our society who do not value whales and dolphins (and
the variety of species in the world). This is why it is important
for the people to be educated about the value of biodiversity
(biodiversity = variety of species) and of the threats that exist
for many species of the world.
There are many people dedicated to educating society about the threats to the
diversity of life on our planet - and this is where you can be very important.
You can educate yourself and the kids in your class about the threats to the
animals you care about. If you can bring awareness to all the kids in your
class, just imagine how that awareness can spread! See if your class wants
to start a campaign to educate other people in your school and in your community.
You could write a play and present it, make an informative poster, write songs,
have an art display inspired by the animals you're studying... be creative!
You could invite guest speakers into your school to talk about the animals
you are interested in, and the threats that they face. You could find out who
to write to in your government, and compose a well-informed letter about why
you are concerned with signatures from people in your class, school, and community.
Education may be the most important step in finding support to help protect
the species of our world. And you have the power to help!
Good luck!
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Whale
Reproduction - received from Andrew in Washington
Q: How do whales reproduce?
A: There are several stages
to whale reproduction.
The first stage, although
this might be pretty obvious, is that a male and a female must
find each other, and approve of the other. Whale species that
live in small social groups or alone undergo seasonal migration
where they go to favored breeding and feeding areas.
In right, bowhead and gray whales, courtship involves groups of whales, typically
one female and many males, and each female may copulate with more than one
male. The method of copulation is quite interesting, in that they are the only
known mammals besides humans and bonobo chimpanzees that mate belly to belly.
One of the pair stays motionless while the other glides beneath. They may hold
the position either horizontally below the water surface, or
vertically, partially out of the water. Mating only takes a few seconds.
The gestation period for a whale is approximately 10-13 months depending on
the species. Mothers typically give birth to one live baby, and the nursing
time is between 4 and 11 months.
Thanks for writing to us!
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Whale
weight gain - received
from Danielle in Arizona
Q: How much do baby whales
gain daily?
A:
Great question! It depends entirely on the species of whale you
are wondering about. Of
the baleen whales, gray whale calves put on an average of 200lbs
a day and blue whale calves put on 176lbs a day. Odontocetes
(toothed whales) this includes, belugas and killer whales, are
smaller whales and their calves probably gain less per day than
the baleen whales. I hope this helps!
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Japanese
Whaling - recieved
from Kimberly from California
Q: What damage is Japanese
whaling doing to the current minke, Sperm, and Brydes whale
populations, and is there a chance that they will become extinct
becouse of overfishing?
A:
This is a very complex and contraversial question. I think
I am safe to say, we probably
don't know yet. The Japanese have only just recently expanded
their hunt to include Sperm and Brydes whales and so we will
not know the effect of thier takes for some time. Sperm and
Brydes's whale populations crashed in the 1950-70's due to
overfishing. This along with population crashes of other species
is what instigated the 1986 moratorium of whaling instituted
by the International Whaling Commission (IWC). Brydes and Sperm
whales are both listed as endangered by the Endangered Species
Act and protected both under it and the Marine Mammal Protection
Act. But, you have to remember that both these acts are American
and apply solely to American waters. The IWC was set up to
regulate the global whaling industry. In order to maintain
a whaling industry, they must maintain stable whale populations.
Hence, the current moratorium. The IWC is not an environmental
or wildlife activist group. They want to keep whale populations
up so that "sustainable" whaling can recommence.
Also, because the IWC is a voluntary international institution,
Japan and Norway originally did not agree with the moratorium
and so simply objected under the "Objection" clause
and therefore are not bound by any regulations set out by the
IWC. This is why when Japan expanded their "scientific" whaling
to include Sperm and Bryde's whales, the IWC could not stop
them. Under the guise of "scientific" research the
IWC says you can take an unlimited number of whales.
Because this is such a recent development in the whaling
contraversy, I cannot give you any stats on how the whale
populations are doing under the stress
of Japan's whaling boats. But, I can give you my opinion. I think if the Japanese
continue whaling taking an "unlimited" number of whales. We will
no doubt in time see some serious repercussions for Bryde's, Sperm and even
Minke whales (the most abundant whale worldwide). The thing is that whales
simply DO NOT need to be killed to do research. Japan claims they are analyzing
stomach contents, population structures and doing population estimates. As
is proven here in British Columbia with the long term study of killer whales
and their social structure and feeding behaviour, wild live research is possible
and highly valuable. So, I think one of 2 things is going to happen: global
protest of Japanese will force them to either 1. stop whaling all together
or 2. at least stop whaling under the guise of research.
For more info about this check out the IWC webpage
I hope this helps. It is a very difficult question to deal with because each
culture should have the right to practice traditional custums even if that
includes whaling, but at what cost? It is extremely thought provoking.
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