Using
Thermography to Study Whales
Wayne Perryman, NOAA Biologist, SWFSC
Claire Surrey-Marsden, NOAA Night Vision Specialist
Introduction: You
know that whale observers look for whale spouts, or blows,
to find the whales. But fog, rain and darkness can make whales
and their misty spouts impossible to see. On the 2010 southbound
migration, biologist Wayne Perryman and his crew tested some new equipment
that
lets them "see" whales despite conditions on the water. This interview lets you discover what scientists are learning from whale breath!
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Wayne
Perryman |
Q.
What gave you the idea to use heat-sensing equipment to study whales?
A. We know from past experience
that
the blow of a whale is much warmer than the ambient temperature and
is
easily
detectable
with modern thermal instruments. We
had the opportunity to test a couple of thermal sensors in fall 2009
during the survey of southbound gray whales conducted from
the
Granite
Canyon Research Station in California.
Q.
What do you mean by modern thermal instruments?
A. Thermal is an adjective that relates to heat. Infrared
radiation (electromagnetic radiation having a wavelength just
greater than the read end of the visible light spectrum but less than
that of microwaves)
is emitted particularly by heated objects. We used a Forward
Looking Infrared (FLIR) camera — a
camera that capture images of objects according the amount of heat they
give off. For example, a thermal imaging camera uses the heat of a whale's
spout to make it visible to humans as an image on a computer screen. The
warm spout of a whale stands out against the colder ocean water or air.
FLIR is also the name of a thermography business that designs and manufactures
hand-held
thermal
imaging
systems
that can
detect
and measure minute temperature differences between objects and their surroundings.
Q. What can you tell us about how the FLIR camera works?
A. The
sensor is a camera that sees mainly in the infrared light spectrum.
We mounted the FLIR camera onto a stand located in a building overlooking
the ocean and plugged the video output directly to a monitor (the screen
on which the photos below appeared). We simultaneously recorded the
footage to a DVR-like hard disk drive. This equipment works rather
like a TiVo that can store the images and allows us to play them in
slow motion to help us determine how many whales are in each passing
group.
We record the footage in the field and bring it back to the lab for
analysis.
Q.
What do the images look like?
A.
Here are some images of the FLIR camera. These are good examples of
how
the technology works. The objects with the higher temperature differential
appear very white.
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 |
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These computer screen images show three different things that passed the camera: a fishing vessel, a whale blow, and a passing jet plane. Which one is shown in each image? Click each photo to see if your prediction is correct. |
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Q. How can infrared cameras, or thermal sensors,
help scientists study whales?
A. These
instruments can help us collect data to (1) evaluate group size estimates
made by visual observers
during the day, and (2) to compare migration rates both night and
day. Previously we found that although whales swim at the same speed
night
and day, about 25% more whales pass at night, but this is only true
during the second half of the migration. Our guess on the cause for
this difference
is that during the first part of the migration there are lots of
pregnant females going by and they are just headed south to calve.
Later in
the season, there are more animals that want to spend time socializing
and
maybe most of that takes place during the day when they can see who
they are dancing with.
Q.
How many FLIR cameras would you need to accurately count whales?
A. This is an interesting question. We are currently working out the
answer ourselves — so no answer yet. The whales are passing through
a "corridor" in
the ocean that seems to average about 1.25 miles out from shore.
When we aim the camera out into the water we know the horizontal
field of
view to be about 11 degrees. We use simple trigonometry to determine
how much ocean we are viewing
through the scope. So one scope sees approximately 450 meters horizontally
and more scopes would increase this range.
Q.
What do you hope to gain by using this equipment?
A. We hope to use this equipment to add to what scientists can already
do, including helping with counts during the day as well as supplementing
information that we can't get by standing regular watches. This equipment
can see the whales passing during the night and might help to determine
if night-time migration differs at all in pace from day time.
Q.
How can we learn more about FLIR cameras?
A. You
can learn more at the product
Web site for the camera we used.
Journal or Discussion Question
- What other helpful uses do you know of — or can you imagine — for thermal imaging? How might it help protect whales from ships?
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