Fishing has long played an important part in the economy of Orkney. Local vessels are all small, and fish predominantly inshore for shellfish. Demersal and pelagic fish are abundant in the offshore waters around Orkney, but these exposed waters can be fished only by large vessels from more distant ports, so that few fish are landed in the islands.

Gadoids, especially haddock, cod and whiting, form the bulk of the demersal fish caught at Orkney. Stocks of all three are giving cause for concern, with declining spawning stock biomass and reduced recruitment. With the coming of processing, more local landing of demersal fish might occur. The closure of the herring fishery in 1977 was followed by a great expansion of mackerel fishing, but with the lifting of the ban west of 4CW in 1981, herring catches have once again become valuable. Because of fishing pressure, landings of both species are subject to quota restrictions.

In recent years, the traditional fisheries for lobsters and crabs have been supplemented by a new fishery for scallops. Lobster stocks are now under some pressure. Conditions around Orkney appear suited to farming filter-feeding bivalve molluscs, and culture and marketing of Pacific oysters has started.