In the article "Dolphin hunt claim denied" (page 3 of mX Sydney, 25 March 2015), Australia for Dolphins chief executive Sarah Lucas refers to "the violent and unsustainable dolphin hunts in Taiji". The article doesn't specify what "unsustainable" means.
I'm not skeptical of the claim the hunt is violent (killing any animal for food is violent), but I am skeptical of the claim the hunt is non-sustainable.
I tried doing a search for dolphin hunting being unsustainable, and only got hits from organizations related to the abolition of dolphin hunting, rather than organizations concerned about the conservation of species or ecosystems.
Is dolphin hunting in Taiji unsustainable?