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Humpback
and fin whale populations are increasing in the Kodiak archipelago, says Bree
Witteveen, a marine mammal specialist and research assistant professor for the
Marine Advisory Program. On Tuesday Witteveen gave a teleconferenced talk with
students at the University of Alaska in Fairbanks, but opened the talk to
Kodiak residents at the Kodiak Seafood and Marine Science Center on Near
Island.
Since 1999,
Witteveen and fellow researchers have been studying whale populations around
Kodiak through the Gulf Apex Predator Prey Project, a program designed to study
various predator species and their effects on surrounding ecosystems. Using
aerial and boat photography, tagging and isotope sampling from skin and
blubber, researchers have gained a greater understanding of where whales
travel, when they travel, how many whales there are and what they are eating.
Witteveen
said a special tagging technique has been especially useful in collecting the info.
"Our approach is to use short term tags,
they just stay on the animal for a number of hours, rather than days or months
like some of the satellite tags do. And they attach to the animal with a
suction cup. So you see the suction cup here, and this black bar here
essentially tells us how deep the whale is diving and this part here with the
antenna coming up is a vhf transmitter, and that allows us to when a tag falls
of it sends us a signal so we can scoop it up."
The depth data,
when combined with elaborate fish finders, helps determine what the whales are
eating.
-- (Whale Seminar 2 :33 "So another part of this is the prey
assessment, and we do this concurrent with our depth assessment. This is where
the benefit of a real time tag comes into play. What we're able to do is
communicate with a separate vessel that is doing specific prey surveys for us.
So we're able to talk to this vessel and well the whales at 100 meters, so they
go over there and they tell us what's at 100 meters. And they do this by using
acoustic sampling of a back scatter, which essentially is just a big fancy fish
finder.")
During the
talk Tuesday night, Witteveen discussed some of the most important findings of
her research, including the surprising amount of fish humpback and fin whales
eat, which she said is equal to commercial fisheries catch.
"Well first of all we can say from those aerial surveys and
from our photo identification work these whales are using the Kodiak archipelago
year round. And they seem to have mostly separate habitats, but there do seem
to be areas where there is spatial overlap. The population of both of these
species are increasing, or at the very least stable. With respect to diets,
when we compare the tagging with the stable isotope data we can start to see
that fin whales are more reliant on zooplankton, and humpback whales seem to be
comprised mostly of fish, and to a lesser extent zooplankton."
Witteveen
said the photography, tagging and sampling tools will continue to be used for
research, but more recently her efforts have been directed toward studying the
relationship between commercial fishing and whales.
"A new addition this last year and we're going to continue it
this year is to look at the humpback whale and fishery interaction, which is
becoming more and more of a problem. And how we're tackling this is we're
putting a different type of tag on these animals, using a pole. And in this tag
is a little hydrophone that essentially records what the whale hears. It
records the sound at the whale. And it also has a 3D way of recording the data.
So not only do we get depth but we get speed and pitch and roll, we get all
kinds of information from this tag. And the idea is to attach the tag and then
record what the whale hears in terms of different deterrents to get whales out
of their net."
She said
humpback whales getting caught in fishing nets are a growing problem, and she
hopes this research will find useful methods to prevent that.
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