I understand the disgusted feelings it evokes in people to see the pictures that have been spread around. I admit that pilot whale killing looks like a brutal bloodbath with all those people participating in the kill running around on shore and in the water, seemingly for no purpose - and with all that blood in the sea.
And some take their children to see how all this is done from A to Z. Not for entertainment but to teach them the facts of life on these islands and how people survive here. That is how it's been done for many centuries.
The Faroe Islanders have monitored their whale killings since 1584, and the numbers show that they have taken an average of 850 pilot whales yearly since then – some years more, some years less, some years none at all. That is approximately 0,1 % of the whole population on average taken every year. (Not 1% as I've seen claimed many places. No, it's ten times less than that: zero point one percent!). This means that the pilot whaling in the Faroes does NOT threat the pilot whale population as a whole. NOAA states that the bycatch to fishing gear is the primary threat to pilot whales. Long-finned pilot whales are entangled, incidentally taken, or interact with a number of fishing gear, that include gillnets, longlines, and trawls. Also threatening this species are heavy metals, pesticides, pollutants, and various contaminants in the marine environment that have been found in this species' blubber.
According to the Faroese themselves, they haven't seen the number of pods swimming by the islands decrease – seen over time – all these years they have killed pilot whales. Of course, there has always been some fluctuation of natural causes, for instance, because some years the pilot whales' own diet – the squids – swim further from the Faroese shores than other years. But the Faroese are convinced that the killing is still sustainable. If the number should decrease it's pretty certain that the Faroese aren't to blame. It's most likely because of changes in the whales' natural environment caused by pollution.