Google Ikejime.

Do they do this on Fugu fish? Not sure. But could be already done. The spinal cord was already severed and the complete column removed?

Ikejime. Is not just about "less cruelty and humane"

Humane is a social construct, to enable social living and make human less of a species with urges for uncontrolled canibalisim.

Ikejime makes the killed fish less stressed and enables the fish carcass to be "fresher" taste better because less stressed, and keeps longer.