Answers from the Gray Whale Expert 2010
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Answers from the Gray Whale Expert
Special thanks to expert Kim Shelden for her time and expertise in responding to your questions below.
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From: Wisconsin
Q: How big is an adult size gray whale brain?
A: A gray whale’s brain weighs about 9.5 pounds (4.3 kg) compared to a sperm whale’s brain which can weigh 22 pounds (10 kg).
From: Texas
Samuel Houston Elementary
Q: How does if feel to be an expert on whales?
A: I don’t think I can ever truly be an “expert” on
whales because there is so much we still do not know or understand
about these amazing animals. But as scientists we continue to study
these animals, to learn where they live, how they survive in their
changing environment, and how we can best protect them so future
generations can continue to see them in the wild.
Q: What is your favorite thing to do with whales?
A: One of my favorite things is to count and photograph
whales. I usually study whales and dolphins from a small plane.
When we find them we want to know how many are in the group and
we do this by circling above the group and counting and videotaping
or photographing the group.
Q:
How do you find the whales?
A: Most of my work takes place in small planes
flying to remote areas to learn where the whales are and to count
how many are there. We fly along tracklines and when we encounter
a whale we circle
and count how many we see. I have also counted whales and porpoises
at sites along the shore where we use binoculars and theodolites
(a surveying tool)
to get information on the location of the animal, which direction
it is travelling, and how many are in the group. Other scientists
I work with
track whales by the sounds the whales make. These scientists use
underwater recording devices that are moored to buoys or dropped
from airplanes. When
they hear a whale they follow the sounds it makes (known as whale
calls) until they see the whale.
Q. How long does a Gray Whale live?
A:The maximum lifespan of a gray whale is not known but there was a report of a large female that was estimated to be about 75-80 years old when she was killed
Q. How deep do they search for their food? What type of food do they eat?
A. Gray whales are wonderfully opportunistic when it comes to what they eat. They skim feed along the surface of the water with mouths wide open to eat copepods. They also eat bottom-dwelling animals such as marine worms and crustaceans (primarily amphipods), by swimming down to the bottom, rolling on their sides, and sucking the mud into their mouths. Gray whales are usually found in shallow waters, along the continental shelf, so they do not have to dive much deeper than 150 meters (about 500 feet).
Q: How long do they stay under water?
A: That would depend on the size of the whale and how it is behaving.
When whales are migrating they may stay submerged for 3 to 5
minutes then surface and take about 3 to 5 breaths before diving
again.
If they are feeding along the bottom they may stay below the
surface for up to 30 minutes.
From:
Minnesota
Q: Why do you think so many gray whales are dying this year?
A: Gray whale deaths and strandings are reported every year
as the whales migrate north from Mexico back to Alaska.
In some years we
see more animals die than in other years and researchers when they
are
able to necropsy (dissect and study) a dead whale try to determine
what may have caused the whale to die. For instance, did the whale
die from starvation, chemical contaminants, natural toxins, entangling
in fishing gear, or was it hit by a ship? Stranding information
has been collected in the Mexico lagoons since 1975 and
in some years
death tolls have been very high. For example in 1980 - 53 deaths
were reported,
in 1982 - 46 deaths, and in 1991 - 45 deaths were reported. In
1999 the death toll was 118, what was unusual about that
year is not only
the high count but that many of the animals were adults - and most
were females. In 1999, deaths continued to be reported as the gray
whales moved north: 42 gray whales stranded in California, 2 in
Oregon, 28 in Washington, 10 in Canada and 73 in Alaska.
The strandings continued
the next year (in 2000). In the Mexico lagoons, 207 dead gray whales
were reported this is an increase from the 118 reported in 1999.
Most were adults but this time there were more males than females.
California
strandings increased from 42 in 1999 - to 57 in 2000. Oregon remained
the same with 2. Washington reports declined slightly from 28 to
23 and Alaskan reports declined from 73 to about 56. Many of the
animals
appeared to be starving. It is important to realize though that
we expect about 800 to 1,200 gray whales to die each year
for a population
the size of 20,000 whales. We haven’t seen large numbers
of gray whales die since the 1999-2000 unusual mortality event.
Q: Why do you think there are fewer babies than there used
to be?
A: The number of calves seen each year at the different research
stations can vary considerably. In some years we see many calves off
central
California during the southbound migration, usually when sea
surface temperatures have been unusually warm during the winter months.
At
the same time, other researchers studying calves in the Mexico
lagoons tend to see lower numbers and these scientists think it may
be because
it is too warm in the lagoons. It may be that during warm years,
mothers that give birth while travelling south do not go all the way
to the
lagoons. Overall, calf sightings have increased across the past
five decades at many of the California counting stations, in part due
to
the increased size of the gray whale population, but the increase
may also be related to environmental changes that may be causing gray
whales
to delay their migration. We have seen a one-week delay in the
migration since the late 1970s at the central California counting station.
Assuming
that the timing when females give birth (parturition) has not
changed, the delay has meant that calving has been occurring farther
north.
Q: What do you think is the most valuable research that's happening
to learn more about gray whales?
A: Gray whales have made an amazing recovery from the time
of commercial whaling. We still have so much to learn about
them
but unfortunately
funding is hard to come by. The greatest threats still continue
to be anthropogenic (human-caused), and these are of concern
for all whales
and dolphins. It is very important to study the effects of
pollution, ship traffic, fishing, and oil and gas development
on the environment
used by these whales.
Q: Do you know what happened to J.J.?
A: On March 31, 1998, J.J. was carried out to sea aboard the
U.S. Coast Guard ship Conifer. Before she was released into
the ocean, scientists
from Hubbs-SeaWorld Research Institute outfitted J.J. with
a radio transmitter, powered by an 18-month battery pack,
to track
her progress.
Unfortunately, the scientists were only able to track J.J.
for two days. No one knows what happened to J.J. after that.
How to Use FAQ's About Journey North Species
Since 1995, experts have contributed answers to students' questions about each Journey North species. These questions and answers are archived in our FAQ's (Frequently Asked Questions) section. You can use today's Answers from the Expert above, along with those from previous years, in the activities suggested in the lesson, "FAQ's About Journey North Species."
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