02155nas a2200205 4500008004100000022001400041245007600055210006900131260003600200300001400236490000700250520152800257653000901785653002001794653001901814100001901833700002201852700001401874856006101888 1979 eng d a0269-727000aThe fish and shellfish resources in seas adjacent to the Outer Hebrides0 afish and shellfish resources in seas adjacent to the Outer Hebri bCambridge University Presscdec a479–4940 v773 a

The demersal fishery in Hebridean seas is based mainly on haddock, whiting and cod, mostly from local spawning grounds, with some recruitment from the North Sea. An important seasonal fishery for dogfish is based on a highly migratory stock. All these stocks are probably fully exploited.

Herring spawning grounds occur west and north of Lewis, and larvae drift eastwards to nursery areas, mainly in the North Sea. Enhanced recruitment in the late 1960s and an increase in fishing effort produced a large increase in landings but these have subsequently declined. The west coast herring fishery is subject to quota regulations for conservation. There are also important exploitable stocks of mackerel and sprats. Since 1971 an industrial fishery for Norway pout has taken a few thousand tonnes per annum.

Shellfishing by small boats goes with crofting. Since 1962 the number of larger boats has increased with full-time fishing, particularly for Norway lobsters and lobsters. Exploitation has been helped by processing and lobster-holding facilities. Scallops and periwinkles are also important commercially and there are good prospects for cultivating oysters and mussels.

By far the largest underexploited fish stock is blue whiting, which migrates south to spawn in March-April on the continental slope in depths of over 400 m to the west of Scotland. The spawning stock in this area is estimated to be 5-15 million tonnes. Sandeels may also occur in commercial quantities in some areas.

10aFish10aMarine Molluscs10aOuter Hebrides1 aBailey, R., S.1 aHislop, J., R. G.1 aMason, J. uhttp://journals.cambridge.org/abstract_S026972700001286001941nas a2200181 4500008004100000022001400041245005400055210005000109260003600159300001400195490000700209520140700216653000901623653001901632100002101651700002301672856006401695 2011 eng d a0269-727000aThe fishes of inland waters in the Outer Hebrides0 afishes of inland waters in the Outer Hebrides bCambridge University Presscdec a377–3930 v773 a

Only euryhaline fishes were able to recolonize Outer Hebridean fresh waters after the last glaciation so that inland waters now contain only six indigenous, truly freshwater species; salmon, trout, charr, three- and ten-spined stickleback and the freshwater eel. Parts of some lochs are invaded by the sea at stages in the tidal cycle and some 20 species of marine fish may be found at times in inland waters. Both salmon and sea trout occur in all the larger freshwater systems and sea trout are also found in many of the minor ones. The original sea trout gave rise to sedentary brown trout populations similar to those of the mainland. Fluctuations in the Hebridean salmon catch suggest that the stock is affected by the same factors as those affecting Scottish west coast stocks generally: the vast-majority return to fresh water as grilse, while sea trout stocks have been declining over the last 25 years. Brown trout and eels are almost ubiquitous. Charr occur in Lewis and parts of North Uist but have not been reported from Harris or South Uist and are now only present as sedentary forms. The three-spined stickleback is more widely distributed than the ten-spined. Outer Hebridean lochs in general have special scientific value because, unlike many Scottish mainland lochs, they have not been affected by the introduction of alien species and some are still in an unexploited state.

10aFish10aOuter Hebrides1 aCampbell, R., N.1 aWilliamson, R., B. uhttp://journals.cambridge.org/abstract{\_}S026972700001280X