Though a fish in itself, smoked fish is referred to as Kippered and often smoked herrings will be referred to as "Kippers". Kipper, the fish, is often referred to as "red herrings".
Trivia from Wikipedia:
Kipper time is the season in which fishing for salmon is forbidden in Great Britain, originally the period 3 May to 6 January, in the River Thames by an Act of Parliament.
Kipper season refers (particularly among fairground workers, market workers, taxi drivers and the like) to any lean period in trade, particularly the first three or four months of the year; possibly a reference to the above usage, or to the need to live frugally during such a period, by (for instance) living off kippers