A Norwegian scientist has reignited the controversy over how hunters can tell if a harpooned whale is really dead.
The whalers use grenade-tipped harpoons (Image: HNA)
The current criteria are based on lack of movement - and the time that takes to occur goes to the core of the debate about the alleged cruelty of whaling.
Animal welfare groups say the harpoon methods are inefficient, and some whales suffer slow agonising deaths.
But Dr Siri Knudsen argues that the present tests may be overestimating the time taken for the animals to die.
She tells the Veterinary Journal that the available data suggests the grenade harpoons developed by Norwegian whalers, and the special training they have received to use them, make for a far more effective slaughter process than many people realise.
Under the rules
In March this year, a coalition of 140 groups highlighted what they said were the inhumane methods used by whaling operations to kill the animals.
The coalition, known as Whalewatch, has been lobbying the International Whaling Commission (IWC) to halt all commercial and scientific whaling.
Three IWC members, Japan, Norway and Iceland, continue to kill whales in accordance with the commission's rules.
These countries use harpoons designed to explode inside the whales. These were developed after many years of argument over how long so-called "cold harpoons" were taking to extinguish life in a hunted animal.
The criteria used by the IWC since 1980 to determine death in these marine mammals rely on observations - looking for the jaw and flipper to slacken, and for all movement to cease.
One small Norwegian study found this happened instantaneously in about 20% of cases; in other cases, movement could be seen to continue for several seconds or minutes after harpooning.
It is Dr Knudsen's view that many of the animals that were seen to move after detonation were also very probably dead - the study showed how the shock wave from the grenade had given the whales a traumatic brain injury (TBI).
Dr Knudsen, from the Norwegian School of Veterinary Science, argues that spinal cord reflexes might cause whales to move long after they have lost consciousness.
And she uses as support for her view scientific observations that seals will withdraw their heads, open their jaws and arch their backs long after their brains have been totally destroyed.
Dr Knudsen calls for more post-mortem studies of whale brain tissue in order to determine the incidence of TBI in animals killed by whaling vessels.
She says this might improve the accuracy of figures for the time taken for whales to die. But she rejects studies that would deploy technical equipment such as EEG to test for insensibility or death in an animal, calling them impractical and dangerous.
"In most countries, including Canada, Greenland, Iceland, Norway, Russia and US, whale hunting is carried out from small skin or fishing boats in Polar waters.
"The animals are large and cannot be restrained or handled before they are dead. The minke whale may weigh up to 10 tonnes," says Dr Knudsen.
"Testing of reflexes or other physiological parameters on these large animals in such cold water, which has been proposed repeatedly, may put people's lives in danger."
Dr Andy Butterworth, a veterinary scientist at the University of Bristol, UK, said that the post-mortem studies called for by Dr Knudsen would only ever reduce figures for time to death.
This is because an absence of traumatic brain injury would not necessarily raise death times, whereas a positive finding would always lower them in animals that previously had been categorised as "still alive" because of some movement seen after harpooning.
He adds that such an approach is likely to be viewed by some opponents of whaling as a subtle effort to massage the data.
"This would put the definition of immediate death into the hands of a pathologist or histologist, rather than those of a veterinarian, present on the deck of the ship, and observing the whale die," he explains.
Dr Butterworth said there was data showing that IWC-approved methods of killing could be inefficient.
A significant number of whales during recent hunts needed a "secondary killing method" to finish them off - usually a large calibre rifle.
The IWC will hold its annual meeting in the Italian town of Sorrento in July.