Humpback whales migrate from the Cook Islands in the South Pacific.
The Great Whale Trail is a collaboration between Greenpeace and
scientists working on humpback whales in the South Pacific. With
financial support from Greenpeace, humpback whales have been tagged
by the Cook Islands Whale
Research and Opération Cétacés (New
Caledonia).
New Caledonia was chosen because the humpbacks which breed there
are members of one of the small, unrecovered populations we're most
worried about.
Dr Claire Garrigue of Operation Cétacés, who directs the study
of humpback whales there, estimates that the population is in the
low hundreds, with little sign of recovery from whaling. Given its
location, we had strong suspicions that the New Caledonia humpbacks
migrate into the feeding grounds which will be one focus of Japan's
scientific whaling in the coming years.
Nan Hauser, who directs Cook Islands Whale Research, typically
photo-identifies only 60 or 70 whales a season. Claire Garrigue may
photograph a whale in the large lagoon off southern New Caledonia
where she works; and a few weeks or years later Nan Hauser may see
that same whale a mile off the coast of Rarotonga (Cook
Islands).
These matches are very important scientifically; but the whale's
movements in between these two farflung points in time and space
are largely a mystery.
In August and September this year, Garrigue and Hauser, working
with Brazilian scientist Ygor Geyer, succeeded in deploying 20
satellite tags on humpbacks - twelve in New Caledonia and a further
eight in the Cooks. All of the scientists working on humpbacks in
the South Pacific eagerly awaited the streams of data that came
from the tags, and they were not disappointed.
By attaching a transmitter to a whale, its movements can be
remotely followed on a daily basis by a satellite. The transmitter
sends a signal to an Argos satellite, which in turn transmits the
data to a ground station - and a scientist with a laptop can access
this information from the comfort of an easy chair anywhere in the
world.
Do New Caledonia whales travel to New Zealand? Do whales in the Cook Islands travel east or west when they leave, or are their movements all over the map?
Satellite tagging can address exactly these kinds of questions, and in doing so can provide critical information about population structure and behavior for use in management.
Although all the tags ceased transmission before any of the
whales reached the Antarctic, the information they yielded was
spectacular.
Of the 12 New Caledonia tags, several traveled from the southern
lagoon by the coast offshore to a remote reef system to the
southeast, and some of the whales remained there for an extended
period.
Until the Great Whale Trail project, no one had any idea of the
apparent importance of this offshore habitat to the animals.
Garrigue is already planning photo-id and genetic sampling in the
area next year, and the tagging results may well set in motion
future efforts to protect this previously unknown habitat.
One whale surprised everyone by leaving the southern lagoon and
moving up the entire length of the western coast of New Caledonia,
and then traveling hundreds of miles west to the area of reefs and
islands known as the Chesterfields.
This provided an interesting historical insight, because in
Herman Melville's day the Chesterfields had been one site of
American "yankee" whaling in the19th century. And then there were
the long-distance migrants.
Some of the whales tagged off New Caledonia moved to Norfolk
Island and/or to the northern coast of New Zealand, thus filling a
key gap in our knowledge of their population structure. The
scientists had always wondered where New Zealand whales went (there
were a few photo-id matches prior to this project).
The movements between these two areas are important, because
whales in neither area have shown signs of recovery from whaling,
and thus the link is a logical one that has significant
implications for conservation.
In this regard, the fact that none of the whales tagged in New
Caledonia moved to Australia provides further support for the idea
that the former is a largely separate stock whose recovery is not
being accelerated by any influx of animals from the much larger
Australian population.
Heading west
In the Cook Islands, the behavior of the eight tagged whales was
characterized by one huge surprise: rather than spreading out and
traveling in different directions, they all moved west.
One animal traveled all the way to American Samoa, while others
moved through the many islands and reef systems that make up the
Tonga group. Does this indicate that whales enter the Cooks in a
kind of "wave" that sweeps through the islands from the east?
The scientists don't yet know, although such movements have been
observed among humpbacks tracked by photo-id in another breeding
area, the West Indies. Another surprise: even though some tags
continued transmitting well into October, which is quite late in
the season - none of the Cooks whales showed any signs of turning
south towards the Antarctic.
This is in contrast to some of the New Caledonia whales, some of
whom began moving south shortly after being tagged. The variability
in these movements, and the consistency with which the Cooks
animals all traveled west, have important implications for a
variety of issues ranging from population structure to how these
animals navigate.
In future months, scientists will be looking in more detail at
the tracks of these animals, assessing whether their movements can
be linked to discernable features in the ocean, the sea floor or
perhaps even the Earth's magnetic field - all of which are possible
mechanisms used by humpback whales to find their way across the
vastness of the ocean.
Valuable information
Although this project was the first of is kind in this region,
and therefore something of an experiment, it has already yielded
far more information about these once-large populations than will
be learned from the upcoming Japanese hunt. Over the next few
months, fifty humpback whales will die in the Antarctic, killed in
the name of scientific research that will tell us little that we do
not already know.
Indeed, virtually nothing in the Japanese lethal studies program
will address the major research recommendations formulated by the
IWC for Southern Hemisphere humpbacks. In other words, the
scientific recommendations of the body that manages whaling are
being largely ignored - and still Japan claims that its science is
useful.
The Great Whale Trail continues.
We may see one or more of our tags spring back to life, and all
of our whales are in a visual database available to researchers
worldwide. You can help ensure they all have names by voting for
the best whale names submitted by whale defenders all over the
world, beginning on the 19th of November.
In the meantime, you can sign up for
Whale Mail and keep up to date on the ongoing developments in
the Great Whale Trail adventure.
The above article is an edit of a longer, more detailed article about the science behind the Great Whale Trail.
Read the full version here.
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