Salmon

A large fish that returns from the sea up rivers to spawn, caught with fixed weirs, traps and nets across rivers. Salmon fisheries were valuable property, often held by lords and monasteries. As a fish it could be eaten on the Church's many meatless fast days, and it was also salted to keep. By 1215 weirs were numerous enough that Magna Carta ordered their removal from the Thames, Medway and elsewhere.

Sources: magnacarta.cmp.uea.ac.uk