Monastic records from the 14th to the 16th century provide evidence of an already well-established fishing economy on the island. Both line fishing and net fishing were practised, inshore in shallow waters and in the deep water offshore, using a variety of vessels: contemporary accounts differentiate between small 'cobles' and larger 'boats', as well as singling out certain specialised vessels (such as a 'herynger', sold for £2 in 1404). As well as supplying food for the monastic community, the island's fisheries (together with those of nearby Farne) provided the mother house at Durham with fish, on a regular (sometimes weekly) basis. Fish caught included cod, haddock, herring, salmon, porpoise and mullet, among others. Shellfish of various types were also fished for, with lobster nets and oyster dredges being mentioned in the accounts. Fish surplus to the needs of the monastery was traded, but subject to a tithe. There is also evidence that the monks operated a lime kiln on the island.