This is an oddity on food from Thomas Platter’s Travels in England 1599. This suggests ways of supplying fresh fish when the fleet were unable to sail, especially in bad weather.
At the fishmarket, in a long street, I saw a quantity of pike up for sale; they are very fond of this, and call it ‘pike’, and feed it with needle-fish (Aiguilles) eels and other tiny fish. And I noticed that each of these fishermen and fishwives kept a copper or brass needle and thread in the tub, with a sharp knife. And when purchasers desired a pike the salesmen and saleswomen slit open its belly at their bidding, placing the guts on their hands to show whether the pike was sufficiently fat, and then sewed it up again: if he pike proved fat enough, then the purchaser took it, but if the guts looked thin and poor the fishmonger kept it, throwing it back into the basin amongst the tenches against which they rub themselves and recover enough to keep them fresh for at least another week, in fact according to them fish could keep fresh for some months.