A lean spiritless creature, a Jack-o'-Lent, like a herring that has shot or ejected its spawn. Herrings gutted and dried are so called also.
Though they like shotten-herrings are to see, Yet such tall souldiers of their teeth they be, That two of them, like greedy cormorants, Devour more then sixe honest Protestants.
Taylor's Workes, iii.5.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894