Humpback whales migrate from the Cook Islands in the South Pacific.
During this time, they do not eat for weeks or months,
subsisting instead on the thick layers of fat (blubber) which have
been steadily built up over the summer feeding season. While on
their breeding grounds, the males sing their long, haunting songs
and compete sometimes quite aggressively over mating access to
Pregnant females give birth to their calves in the warm tropical
water, and diligently nurse them with a fat-rich milk that promotes
rapid growth. Then, at winter's end, all the whales make the long
journey back to polar waters, and the annual cycle begins once
It is a cycle that has been repeated for thousands of
generations of whales, over what may well have been millions of
years. It is strange to think of how long the world's oceans have
resonated with the songs of humpback whales, and even stranger to
consider that, through uncontrolled whaling, humans came close to
permanently silencing this ancient chorus, and barely half a
In the Southern Hemisphere, humpback whales feed in the frigid
waters off Antarctica, and they breed and calve in coastal or
island waters that stretch in a global band between the equator and
the Tropic of Capricorn. A particular whale's particular feeding
and breeding grounds are determined largely by where that whale's
mother comes from.
If your mom was a whale who fed in the
waters south of Australia, then that's where you yourself will
return each spring to eat.
If your mom was a whale who migrated to Fiji to give birth to
you, then Fiji is probably where you will head when it is your turn
to breed. Except that Fiji no longer hosts very many whales.
Today, a handful of humpbacks return there, and one can wait a
long time between sightings, even during the supposed peak of the
season in August. Yet it was not always so.
In the 1950's, the late Dr William Dawbin conducted annual
surveys for humpback whales at various places in Fiji, and recorded
several hundred whales a week at the peak.
However, this was before 1959, when the USSR - which at that
point had already been engaged in a secret campaign of illegal
whaling for more than ten years - began a slaughter of humpback
whales that was excessive even by the unrestrained standards of
20th century whaling.
Over the course of just two winters, Soviet factory ships
slaughtered almost 25,000 humpbacks; most met their end in the
portion of the Antarctic that lies south of Australia and New
The result was an instant crash of the population - so rapid
that coastal whaling stations operating to the north, in New
Zealand and eastern Australia, almost immediately went out of
business for lack of whales.
We do not know how small the surviving humpback whale population
was, but it was likely just a few hundred animals. In the four
decades since those dark days, humpback whales have recovered
remarkably well - in some areas.
Off eastern Australia, for example, the population is now on the
order of several thousand animals, and continues to grow at a
healthy rate. But in other places, including Fiji, New Zealand and
New Caledonia, there is little or no sign of such recovery.
Whether this is because the cultural memory of the existence of
these formerly populous habitats died with the slaughtered whales
is not clear. And today, after almost half a century of protection,
humpback whales will once again be hunted in the Antarctic.
Later this month, the Japanese whaling fleet will leave its home
port and head for the Antarctic, where it intends to kill up to 935
minke whales as well as 50 fin whales and 50 humpbacks.
These catches will continue each year, indefinitely, in the
latest phase of Japan's "scientific" whaling program - a program
which has been widely discredited by numerous scientists, and which
is seen as a convenient way for Japan to circumvent the global
moratorium on commercial whaling enacted by the International
Whaling Commission (IWC) in 1986.
Under the terms of the 1946 International Convention for the
Regulation of Whaling (which established the IWC), any nation may
issue its nationals a permit to kill whales for the purpose of
studying them. Such a provision made perfect sense sixty years ago
when the Convention was signed; in those days, there was no other
way to study whales except by killing them.
The provision (known as Article VIII) was intended to allow
scientists to kill small numbers of animals for study; it never
included a limit to the number of whales that can be killed,
because in 1946 no one imagined that Article VIII would ever be
used as a way of getting around a ban on whaling.
One of the big problems with Japan's intended catch of humpback
whales is that it is impossible for a harpooner to tell whether the
whale in his sights comes from the relatively healthy population
off Australia, or from one of the small, unrecovered stocks in
places like Fiji and New Caledonia.
Although 50 whales a year may not seem like a huge number when
set against the massive totals racked up by the USSR and other
whaling nations in the 1950's and 60's, such catches have the
potential to threaten the remnant populations that are struggling
to make a comeback.
Key to all of this is a knowledge of population structure.
Specifically, in order to properly manage any whale species, one
needs to know how many populations exist, and their size and
relationship to one another.
The importance of this can be illustrated with a simple example.
Imagine that there are a thousand humpback whales in a single
population -that these animals mix freely with each other, and that
they all breed together.
Now imagine that each year a certain number of these whales are
killed by "unnatural" causes - whaling, entanglement in fishing
gear, ship strikes, et cetera. The impact of these mortalities on a
single stock of a thousand whales will be far less than if the
thousand animals actually make up two separate populations, with
one being 900 and the other only 100 animals.
The impact of any number of deaths on a population of a hundred
will obviously be a lot greater than if that same number of
mortalities is taken from a single, mixed stock of a thousand
In other words, you need to know how many populations you're
dealing with before you can make sensible decisions about how to
manage them. For the purpose of management, scientists and the IWC
usually define populations by drawing lines on a map; this is
inevitable and convenient, but of course the whales themselves
don't recognize such neat boundaries.
Currently, the IWC recognizes seven Southern Hemisphere
populations of humpback whales. Each of these populations feeds in
a particular portion of the Antarctic, and these feeding areas are
linked to specific breeding grounds in tropical waters.
For example, humpbacks that feed in what is known as "Area V" -
broadly, the area of the Southern Ocean south of Australia and New
Zealand - are thought to breed off the eastern coast of Australia
and in western Oceania.
Management of these animals - an activity which could cover
everything from conservation measures to setting future catch
quotas - is all based on the assumption that this population is
largely separate from others (which in turn are managed according
to our knowledge of their particular size and structure).
How do we study population structure?
There are various methods, most of which involve somehow
tracking whales from one place to another, and in the process
testing whether our notions of the structure and boundaries of
their populations are accurate.
For example, if a whale from eastern Australia suddenly showed
up in the Antarctic south of Africa, this would challenge the
current idea that the Australian population is linked to feeding
grounds in the polar waters south of that continent.
How serious a challenge this would represent would depend upon
whether such movements turned out to be fairly common, or looked
instead like a one-shot case of an "aberrant" wandering whale.
To date, incidentally, no such movement has been detected,
although scientists working in the Indian Ocean did recently record
a whale going from the east coast of Africa to the west!
How to track whales
The principal means of tracking whales from place to place are
threefold. The first is photo-identification, which involves
photographing the unique markings on the underside of a humpback
These markings are like a fingerprint in that no two whales have
exactly the same tail pattern, and this feature has been used to
identify many thousands of individual humpback whales all over the
Photo-id has allowed scientists to follow individual whales over
periods of literally decades in some areas, and also to document
the reproductive success of females and their offspring over
A second method is similar but more high-tech. By taking a tiny
sample of skin from a humpback whale through a biopsy - a dart is
fired at a whale from a crossbow, and harmlessly takes a small
sample before bouncing off into the water - scientists can examine
the whale's DNA and conduct many sophisticated and highly
These including determining the animal's sex (which usually
cannot be done visually), as well as assessing its maternal
lineage, and constructing a genetic profile that allows the whale
to be individually identified.
As with photo-id - where two photographs of the same whale in
different areas can be matched - a humpback biopsy-sampled in two
different places can be unequivocally identified as the same
individual through genotyping.
All of these tests and many more can be conducted with a single
tiny piece of skin - rather different from the "whole-animal"
sampling employed by Japanese whalers.
With either of these methods, an individual whale can be
resighted or resampled again and again, giving us ever-more
information about its movements over the course of years or even
its entire life (something which, needless to say, is not possible
when a whale is killed - you get one data point, and that's
Using these methods, thousands of whales have been documented
traveling over sometimes huge distances. For example, in the North
Atlantic, some humpback whales have been followed for more than
thirty years, and observed at migratory endpoints as far apart as
Norway and the Caribbean.
However, what photo-id and genetics cannot do is tell us the
daily movements of animals, or to track their wanderings through
the large areas of ocean in which human observers aren't
We may photograph a whale in the Cook Islands or New Caledonia
and then see it again off Tonga (in fact, many such matches have
been made with both photographs and genetics); however, we don't
know the many details of where it goes in between these brief
snapshots of its life. This is where the third technique comes
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
Photo-id and genetic sampling requires scientists to be next to
the animal, and it is impossible to follow the whale in rough
weather, or at night, or far from the safety of coastal waters. In
contrast, a tagged whale can be followed anywhere on Earth, at any
Not only do scientists get to see the end points, but they learn
every detail of the whales movements without ever having to
relocate the animal in the vastness of its huge migratory range
(traditional methods require you to find the whale to photograph or
biopsy it - and that is as much a matter of luck as anything
This year, a group of scientists working in the South Pacific
were funded by Greenpeace International to conduct a collaborative
satellite tagging project in two locations: New Caledonia and the
Cook Islands. New Caledonia was chosen because this is one of the
small, unrecovered populations about which we have considerable
concern relative to the imminent Japanese whaling effort.
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 Area V feeding grounds which
will be one focus of Japan's scientific whaling in the coming
Indeed, a recent genetic match of a whale moving between these
two areas has confirmed this. Whales from the Cook Islands likely
migrate further to the east than the New Caledonia animals, and the
population there is even smaller.
Nan Hauser, who directs Cook Islands Whale Research, typically
photo-identifies only 60 or 70 whales a season. Again, tagging
fills in the gaps.
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
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.
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
Last year, Hauser's project placed a single satellite tag on a
whale - a mother observed off the main island of Rarotonga -and
watched over four months as the animal migrated from the Cooks into
the Southern Ocean.
By the time the tag ceased transmitting in late January 2007,
the whale had traveled almost 4000 km to the Antarctic Circle, and
was close to the boundary between two IWC management areas - which
came as a surprise to many.
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.
Although all the tags ceased transmission before any of the
whales reached the Antarctic, the information they yielded was
spectacular. Because by necessity we usually work close to our own
coasts, we tend to fall into the trap of seeing humpback whales as
coastal animals, yet they are not.
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 then, 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. We 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
In the Cooks, 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 the
through the many islands and reef systems that make up the Tonga
Does this indicate that whales enter the Cooks in a kind of
"wave" that sweeps through the islands from the east?
We 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 was that - 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
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.
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.
With just these twenty animals, we have already learned more
about movements and connections of whales in the South Pacific than
was known before. Satellite tagging of course cannot tell us
everything; rather, it is used to address some specific areas of
research, and not others.
But in combination with other non-lethal approaches such as
photo identification, genetic analysis and other techniques, it can
provide far better information for the conservation and management
of these animals than "scientific" whaling ever will.
This information was provided by the scientists researching humpback whales in the South Pacific who are collaborating with Greenpeace on the Great Whale Trail.