Evaluation of Ecological Effects of the North Sea
301
sandeel, Raitts sandeel and smooth sandeel are on average up to 25cm long and
comprise the majority of commercial catches. The much larger Corbins and greater
sandeel grow to 35cm and can be a smaller part of the commercial catch.
Sandeel are shoaling pelagic fish. They prefer sandy or sand/gravel mixtures
on the seabed to bury in. Sandeel are distributed widely throughout the North Sea.
However, the main commercial fishery is conducted to the west of Jutland in Denmark,
and on the Dogger Bank in the central southern North Sea and off the east coast of
Scotland from the river Forth estuary northwards. A small fishery exists in Shetland
waters.
Sandeel feed mainly on planktonic copepods and crustacean larvae. Some
polychaete worms, amphipods and euphausids are also eaten. The greater sandeel also
feeds on fish including other sandeels. In general the species live for about five years.
Sandeels are believed to bury in the sand during winter but many are found in the
stomachs of predators during this period which may suggest that they are available for
food for periods of the winter or that predators dig them from the sand. They
apparently spawn during winter and produce demersal eggs which adhere to the
seabed. sandeels are a major food source for a variety of fish, seabirds and marine
mammals. They are captured by demersal trawls constructed with very small meshed
netting.
Norway pout is found in the northern and central areas of the North Sea. It is
usually found at 80 to 200m water depths but can also be found at up to 450m in the
Norwegian Deep. It is a small (10-20cm) species rarely attaining four years old.
Mature fish diet consists of crustaceans and small fish. It is generally found near the
seabed and the commercial fishery is carried out mainly by demersal trawls. Like
sandeels, Norway pout are an important food for other fish species within the North
Sea. Like sandeels the pout are captured within very small meshed demersal trawls.
Fig. 2 shows the landings by year since 1953 for sandeel and from 1959 for
pout (Anon, 1996). The sandeel fishery enjoyed a steady increase in catches up to 1977
from when a concerted effort began to increase catches to a high of just over one
million tonnes in 1989. Some 775,000 tonnes have been taken on average by the
fishery, each year over the last ten years. Landings from the pout fishery rose steadily
to 1994 from when a decrease has occurred due partly to the imposition of a Total
Allowable Catch (TAC) on the fishery and the establishment of the “pout box” in 1985
which reduced the area for pout fishing. Interestingly, the pout box was set up as an
exclusion zone for pout fishing to protect human consumption species which had
previously been captured as by-catch in large quantities within the small meshed pout
trawls. Elsewhere in the North Sea by-catches of human consumption species are still
taken within the pout fishery.
The sprat is mainly concentrated in the southern section of the North Sea and
in the case of summer juveniles, particularly in the German and Southern Bights.
Some are found in the Moray Firth where there was a large fishery in the nineteen
sixties and seventies. It does not occur to any great extent in the northern or central
301
sandeel, Raitts sandeel and smooth sandeel are on average up to 25cm long and
comprise the majority of commercial catches. The much larger Corbins and greater
sandeel grow to 35cm and can be a smaller part of the commercial catch.
Sandeel are shoaling pelagic fish. They prefer sandy or sand/gravel mixtures
on the seabed to bury in. Sandeel are distributed widely throughout the North Sea.
However, the main commercial fishery is conducted to the west of Jutland in Denmark,
and on the Dogger Bank in the central southern North Sea and off the east coast of
Scotland from the river Forth estuary northwards. A small fishery exists in Shetland
waters.
Sandeel feed mainly on planktonic copepods and crustacean larvae. Some
polychaete worms, amphipods and euphausids are also eaten. The greater sandeel also
feeds on fish including other sandeels. In general the species live for about five years.
Sandeels are believed to bury in the sand during winter but many are found in the
stomachs of predators during this period which may suggest that they are available for
food for periods of the winter or that predators dig them from the sand. They
apparently spawn during winter and produce demersal eggs which adhere to the
seabed. sandeels are a major food source for a variety of fish, seabirds and marine
mammals. They are captured by demersal trawls constructed with very small meshed
netting.
Norway pout is found in the northern and central areas of the North Sea. It is
usually found at 80 to 200m water depths but can also be found at up to 450m in the
Norwegian Deep. It is a small (10-20cm) species rarely attaining four years old.
Mature fish diet consists of crustaceans and small fish. It is generally found near the
seabed and the commercial fishery is carried out mainly by demersal trawls. Like
sandeels, Norway pout are an important food for other fish species within the North
Sea. Like sandeels the pout are captured within very small meshed demersal trawls.
Fig. 2 shows the landings by year since 1953 for sandeel and from 1959 for
pout (Anon, 1996). The sandeel fishery enjoyed a steady increase in catches up to 1977
from when a concerted effort began to increase catches to a high of just over one
million tonnes in 1989. Some 775,000 tonnes have been taken on average by the
fishery, each year over the last ten years. Landings from the pout fishery rose steadily
to 1994 from when a decrease has occurred due partly to the imposition of a Total
Allowable Catch (TAC) on the fishery and the establishment of the “pout box” in 1985
which reduced the area for pout fishing. Interestingly, the pout box was set up as an
exclusion zone for pout fishing to protect human consumption species which had
previously been captured as by-catch in large quantities within the small meshed pout
trawls. Elsewhere in the North Sea by-catches of human consumption species are still
taken within the pout fishery.
The sprat is mainly concentrated in the southern section of the North Sea and
in the case of summer juveniles, particularly in the German and Southern Bights.
Some are found in the Moray Firth where there was a large fishery in the nineteen
sixties and seventies. It does not occur to any great extent in the northern or central