For half a century, Takeo Nakajo has been catching katsuo (bonito, or skipjack tuna) — indispensable in Japanese cuisine whether eaten raw, dried or used as a base for the broth.
But he and other fishermen in the southwestern city of Kure, Kochi Prefecture, have seen something worrying in the past two years — an unprecedented number of unusually fatty katsuo.
While heavier katsuo means more money, locals and experts say it indicates climate change and a risk for katsuo numbers already under threat due to growing demand and overfishing.