A "humane" killing is relative: some killings more humane, some less. Let's compare whaling with farming and with hunting.
Farming
The usual/legal standard for slaughtering farm mammals is to stun them (perhaps using a bolt gun) before bleeding them.
Whether that's always done successfully is another story.
The slaughter of farm animals using such methods is more-or-less widely seen as humane: legislation such as the Humane Slaughter Act implies that method is humane by definition and by law.
Hunting
Here's a description of hunting:
During regular hunting of wild terrestrial game with
rifles, the projectiles are usually directed at the thorax area
to damage the circulatory system by injuring the heart, lungs
and/or main thoracic vessels. The animal loses
consciousness and subsequently dies from the impact shock
and/or the rapid fall in blood pressure by puncture of the
circulatory system.
Whaling
This method can't be used for whaling:
However, this method cannot be
successfully used for euthanasia of whales during hunting as
the thorax is under water and water has a considerable
braking effect on a rifle projectile. In trials on dead common
minke whales, Øen (1995a) found that a 20mm 3 66mm
high-velocity bullet with impact energy of 60kJ, which is
about ten times the impact energy of the rifle projectiles
used in the present study, travelling 1m or more through
water before hitting the whale, stopped in the blubber. Only
direct hits went sufficiently deep into the animal to give the
potential to kill. A rifle bullet will therefore hardly
penetrate the blubber if it hits water first.
Therefore a 'heart shot' can be used to attempt euthanasia only for a beached/stranded whale:
However, for
euthanasia of stranded whales, which in many cases have
the thorax area out of the water, a rifle shot through the
heart or main vessels with sufficient ammunition, will
probably kill the animal rather quickly, although not
instantaneously.
Therefore they shoot for the brain as suggested in your question:
Consequently, for the euthanasia of whales in water, the
primary target area for rifles is the brain and for a whale of
the size of a common minke whale a heavy, round nosed or
semi butt, full-jacketed bullet with high impact energy and
sectional density is recommended to avoid splintering,
ricocheting and deviation by passing hard tissue. The brain
of a common minke whale is approximately 20cm in length,
20cm in width and 15cm in height (Knudsen et al., 1999).
This is a relatively small target as it is exposed over water
only for a couple of seconds at a time. However, the
shooting range is usually short and the results from the
present study demonstrated that the .375 and .458 missiles
caused fatal damage to the brain, and killed the animal
instantaneously or very rapidly also when it hit and
penetrated the skull as far as 20cm from the brain.
Consequently, when using the recommended .375 and .458
calibre bullets, the lethal hitting area will be larger than the
brain itself, increasing the potential for rapid kills.
Additionally, the study also demonstrated that hits in the
spine in the neck resulted in brain damage and very rapid
death. This was demonstrated even when the whale was hit
as far back as to the 2nd thoracical vertebrae.
Whalers first hit the whale with an explosive harpoon. Reasons for using a harpoon might include:
- They travel through water better than a bullet
- They're an explosive weapon, not a kinetic weapon
- A whale will sink when it's killed, so they want to spear it with a line to catch/hold it
The rifle is used as the second/backup method if the harpoon strike didn't (in the opinion of the gunner) kill the whale.
During hunting, the rifle is kept beside the marksman and
the whales are to be hauled in rapidly for control after the
impact of the harpoon. The rifle is usually fired from close
range and when the whale’s head is out of the water. The
hunter aims at the brain (Fig. 1), which, depending on the
size of the animal, lies 55 to 75cm behind the blowhole
(Knudsen et al., 1999). An illustration chart with the
position of the brain and aiming point from different
shooting angles and directions has been distributed to all
Norwegian whaling vessels. Rifle shots are fired at any
whales that show movement, if the flippers or jaws are not
relaxed or if the hunters suspect it may still be alive. In
2001, 79.6% of the animals were recorded instantaneously
dead from the grenade detonation (Øen, 2002).
Nevertheless, the hunters used the rifle on 45% of the
whales as many use the rifle as a matter of routine when the
whale is alongside the boat (Øen, 1995;2002).
So according to this, somewhere between 20% and 50% of the whales are not killed by the first (exploding) harpoon, and are finished by rifle a close range.
Norway's technology is state of the art (i.e. others are worse).
This 2003 IWC report says things like,
Norwegian grenades showed superiority in every
experiment. TTD of Norwegian grenades in every
experiment were shorter than Japanese grenade and
Instantaneous Death Rate (IDR) of Norwegian grenades in
every experiment were higher than for Japanese grenades.
Norwegian grenades showed excellent results especially for
small individuals. However, financial concerns may be the
most important factor related to the decision on whether or
not to introduce them to Japan.
And:
It was commented that this was a very valuable and
interesting paper. In reply to a question about the possible
use of these bullets at shooting ranges of up to 50-100m,
ÿen answered that they had no experience of longer
distances since all the whales in Norway were shot at a
much shorter distance. In the present study the mean
shooting distance was 9.3m.
And:
New Zealand indicated that the research presented tp
this Workshop suggested a current level of best practice for
determining the minimum specifications of rifles used to
kill whales (being a minimum calibre of .375 inches with
round nosed full metal jacketed bullets) and that it would
be appropriate to consider a broad implementation of these
best practice standards. While there was general agreement
that all countries should be encouraged to use the best
available techniques to kill whales, it was acknowledged
that there were substantial practical and financial
constraints for aboriginal subsistence whalers. It was
agreed that the Workshop had been constructive in striving
to improve whale killing methods and the encouragement
of the adoption of such measures would be warmly
welcomed.
The above are quotes from IWC and Norwegian papers. I used them because:
- They're first-hand or expert witnesses
- They are not overtly anti-whaling
There's a longish page titled HUNTED DEAD OR 'STILL' ALIVE which argues from the opposite point of view.
It has dozens of points to make (which you can read there but which I won't summarize here). One of them is this,
During the 1999 IWC Workshop on Whale Killing Methods, one expert noted that ‘causing humane death without pain in meat animals usually includes the induction of instantaneous insensibility by stunning. Instantaneous in this context is embodied in European Union Legislation which requires a limit of about 100 milliseconds between stimulus (application of stunning device) and unconsciousness. The figure of 100 milliseconds is based on the pain perception delay of 100 to 150 milliseconds found in meat animals.’
Clearly, modern whaling techniques do not come close to delivering ‘death without pain, stress or distress’. All current whaling methods include a chase and, even in hunts where more powerful killing weapons are used, irreversible insensibility or instantaneous death – the key to a humane kill – is still not achieved in a significant number of cases.
That seems to be to be true, i.e. matching the evidence previously presented above:
- "Humane" for farm mammals is defined as meaning near-instant unconsciousness
- This (being killed semi-immediately) doesn't happen for a large number (at least 20%) of the Norwegian whales
The numbers are worse for non-Norwegian kills; for example,
Norwegian whalers aim the explosive harpoon at the whale’s head, or just behind it, which results in a greater number of animals dying instantaneously (79.7% in 2001) and a shorter average time to death (2 minutes and 25 seconds). In contrast, their Japanese counterparts deliberately avoid the whale’s head in order not to damage the fragile “ear-plugs” which they collect as part of the study that supports their claim to be conducting ‘scientific whaling’. A strike to the body of the whale can cause extensive tissue and organ damage, but may deliver insufficient energy to the brain. Japan only achieved instantaneous death in 33% of its minke whale hunts in Antarctica in the 2001/2002 season and an average time to death of 3 minutes and 23 seconds. Since 2000, Japan has expanded its hunts to species much larger than minke whales (Bryde’s whales are at least twice as heavy, sei whales about five times heavier and male sperm whales are not only nearly six times heavier but have an entirely different anatomy). Despite this wide variation, Japan is believed to use the same size harpoon on each species, but refuses to provide data on the time they take to die.
Older techniques e.g. old-fashioned grenades used in 1995 resulted in some times-to-death of an hour or longer, and up to 40% of the whales not being landed (e.g. escaped wounded).