Dolphin hunting is bad for two reasons: cruelty and conservation.
It is difficult to imagine the suffering dolphins and whales hunted in Taiji experience, from the panic and exhaustion of their capture to their excruciating deaths.
When we take into account that dolphins and whales are highly emotional animals with strong social ties, and that the period of extreme distress can last days, it is difficult to think of a practice more cruel to animals anywhere in the world. In the words of Dr Diana Reiss and Dr Lori Marino, two of the world's foremost dolphin scientists, Taiji is "a stunning example of breathtaking cruelty".
Taiji's drive hunt industry is cruel not only to the dolphins killed in the slaughter cove, but also to those spared from slaughter and sold to aquariums to become performing animals. Dolphins and whales captured in Taiji are sold to aquariums in countries with little or no animal welfare legislation, where they are often kept in appallingly inadequate conditions. According to the World Society for the Protection of Animals, 53% of dolphins captured in drive hunts die in the first three months of captivity.
On top of its cruelty, drive hunting is also a serious conservation concern.
Most of the species hunted at Taiji exist in large populations around the world, and are not considered to be at risk of becoming endangered or extinct. But intensive drive hunting has had a devastating effect on populations of dolphins and whales that migrate past Japan, with unknown consequences for marine ecosystems.
The IUCN Red List, the most comprehensive list of the conservation status of biological species, states that the striped dolphin, the most exploited species, has been "completely or nearly eliminated" from Japanese coastal waters. There have been steep declines in catches of other species targeted by drive hunting, such as bottlenose dolphin and pantropical spotted dolphin, indicating depletion of these populations.
The IUCN notes that the drive hunting method - which involves intensive harassment of the animals causing sometimes fatal injuries - can kill many more than just those captured, multiplying the damage done to dolphin and whale populations.
In 2013, the Environmental Investigation Agency published the most up-to-date analysis of the conservation impact of Japan's small whale hunts, finding that catch limits are set at unsustainable levels for eight of the nine exploited species, and their continued unregulated hunting risks some populations with extinction.
While the IUCN conservation status of most species killed in Taiji is "Least Concern", the short-finned pilot whale and false killer whale are listed as "Data Deficient", indicating that their global populations are unknown. Short-finned pilot whales that migrate along the Japanese coast have been reduced to a population of 4,000-5,000. False killer whales are also relatively rare. The IUCN lists drive hunting as a "major threat" to both species. It is not known how many short-finned pilot whales and false killer whales live elsewhere in the world to maintain these species if drive hunting eliminates the populations unfortunate enough to pass Japan.
What is clear is that the Japanese fishermen pay no attention whatsoever to the ecological and conservation damage they cause every day for 6 months of the year.