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Gray whales are confusing animals.

Go back just three years, and the accepted wisdom was that there were two populations in existence.

The larger one lived on the eastern side of the Pacific Ocean with an annual migration route down the west coast of North America.

A much smaller one dwelt in the western Pacific, off the eastern coast of Russia, migrating south as far as Korea and China.

While the eastern population has regrown after the commercial whaling era to a healthy 20,000+ individuals, the western gray whale is among the world's most endangered cetacean populations, numbering about 150 animals.

Will it follow the population that used to live in the Atlantic Ocean into extinction?

If the answer to that question was unclear three years back, it's now as murky as the sea-bottom sediments in which gray whales feed.

Two years ago, aiming to track western gray whales from their summer feeding grounds off Russia's Sakhalin Island to their unknown winter breeding places further south, researchers tagged a male that they dubbed Flex.

To their surprise, it headed not south but north-east - eventually ending up among the much larger eastern population.

Guide to the great whales Blue

Bowhead

Fin

Bryde's

Right

Humpback

Sei

Gray

Sperm

Minke

At last year's International Whaling Commission (IWC) meeting, scientists revealed they'd used photos to identify a total of 10 grays that spent time on both sides of the Pacific; and this year, we're up to 14.

That might seem a small number; but it's 10% of the population, so significant.

Yet genetic studies indicate the two populations are pretty much distinct.

You might ask why this matters; aren't the habits of gray whales just a scientific curiosity?

Well - no. It has clear ramifications in at least three areas.

One concerns oil and gas exploration.

The western gray whale feeding grounds close to Sakhalin are also the location of a major gas field.

The company Sakhalin Energy already has two platforms close to shore in Piltun Bay, whose shallow waters are especially used by calves.

A third Piltun platform is mooted, while another company, Exxon Neftegas, has begun work on a facility further offshore near a feeding area used by adults.

There's documentary evidence - some of it obtained through research activities funded by Sakhalin Energy under the Western Gray Whale Advisory Panel - that seismic exploration and platform construction both disturb the whales.

At this year's IWC meeting here in Panama, Russia's commissioner Valentin Ilyashenko caused some consternation among environment groups when he appeared to say that construction of the third Piltun platform was a foregone conclusion.

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However, Sakhalin Energy later confirmed to me that it is a "possible eventual development" and that a full environmental impact assessment will be undertaken if and when it was decided to go ahead.

So here's the point. If a significant proportion of what was thought to be the western gray whale population is in fact migrating and breeding in the east, what's the true size of the western population?

The IWC's scientific committee summarised it so: "The number of whales in the western North Pacific population is potentially smaller than the currently estimated ~150 whales that use the Sakhalin summer feeding area.

"Thus, the status of gray whales in the western North Pacific may be of greater conservation concern than is currently recognized."

And the potential impact of oil and gas extraction, therefore, potentially bigger.

The second implication concerns the application by the Makah, a Native American people living on the western coast of the US, to hunt grays under IWC rules on aboriginal subsistence whaling (ASW).

It's already a controversial application for a number of reasons.

But if there's a chance the Makah might take one of the few western gray whales that's strayed to the other side of the ocean, that will be seen by some governments as another reason why the request should be turned down.

The third reason is that gray whales, like many other cetacean species, are already being affected by pollutants in the sea - the so-called "stinky whale" phenomenon - and are likely to be further compromised by climate change, as it alters the seasonal patterns of sea ice growth and retreat and the food supply.

One gray unexpectedly went "walkabout" in the Atlantic and Mediterranean a couple of years ago, with the suspicion being that it navigated the Northwest Passage.

In order to project what these changes will mean for gray whales, it's vital to understand where they currently go - and ideally, why.

The imminent prospect of oil and gas exploration in other parts of the Arctic is another factor that could potentially have grave impacts for grays and other species - again, understanding their current habits is key in making sensible decisions on where, when and how to explore.

Further sighting and tagging projects are planned. They may yet write the natural history of gray whales in black and white.