Where can I find a Kipper?

Answer

A kipper is a smoked herring that's been parted and cleaned.

you

Almost right.

A kipper is a spent male salmon.( a male salmon that has shed its roe or melt)

The name kipper is used because the best kippers are processed from herrings that have shed their roe (spent) and and have recovered They are then full of fat before the next spawn. Normally summer herrings are the best for smoking.