It's simply a matter of counting deaths versus births, he explains.
There had been optimism about the prospects of the North Atlantic right whales after last year's birth of 28 calves — up from 16 the year before, said Kraus. But when the number of deaths is factored in, plus the number of individually identified whales known from surveys that have just disappeared — never to be seen again — the death rate of the whales is more like 47 over the last 16 months, said Kraus.
"The fact of the matter is that we're still killing them off at a rate that is unsustainable," said Kraus.
That means the North Atlantic species of right whales will certainly go extinct without immediate and decisive action, said Kraus.
Because the North Atlantic right whales are protected from commercial whaling, the leading causes of death are collisions with boats and entanglements with fishing gear, Kraus says. Re-design of fishing equipment would help, but the same laws that are designed to protect the whales have proven dangerously sluggish in approving new, whale-friendly fishing technology, he said.
The fate of the North Atlantic right whales bodes unwell for other whales too, said whale researcher Todd O'Hara of the University of Alaska at Fairbanks.
"The North Atlantic right whale is not unique," O'Hara said of the deaths from boat collisions and fishing gear entanglement. The same problems exist for the North Pacific right whale, as well as other Pacific whale species, he said.
"This is not just a regional management issue," said O'Hara. "We should be looking at (the North Atlantic right whales) closely because it could be a sign of what could happen elsewhere."
One of the frustrating contradictions in the battle to save whales today, says O'Hara, is that despite historic drops in commercial whaling, whales are still facing growing threats from fisheries and more traffic along shipping lanes.
But deaths from collisions and fishing gear entanglements don't seem to outrage the public the way whaling did, he said.
There is far more of a public outcry, for instance, when a few whales mysteriously strand themselves on beaches than when scores die from human activities at sea, said O'Hara.
"In this case we know what the causes of death are," said O'Hara, but the measures to prevent the deaths still aren't in place.