317
Evaluation of Ecological Effects of the North Sea
available on the western side along the English and Scottish coasts, on the Dogger
Bank and across the Dutch coast and northwards along the offshore Danish coast.
Whiting associate with the entire north-south length of the North Sea during
winter. They may well be taking advantage of the pout in northern parts during winter
months as well as sandeel, sprat and juvenile herring in southern parts over the whole
year.
TOTAL SANDEEL CONSUMPTION BY THE ANIMAL KINGDOM
Adding seabird consumption of, on average, 200,000 tonnes of sandeel per annum,
mammal outtake of 45,000 tonnes (both these estimates are taken from Anon, 1994;
the mammal consumption does not include that taken by the estimated 380,000
porpoise in the North Sea) and the commercial catch (as indicated in ICES ACFM
reports) to the consumption by fish predators gives a total consumption set out in Fig.
11. This is compared with the Spawning Stock Biomass and Total Stock Biomass
calculated by ICES for each year from 1976 to 1992. Apparently, total consumption of
sandeels equates to the total stock available. ICES do not place confidence limits to
their sandeel stock assessment and this may explain why our takeout plot lies higher
than the total stock for some years. Even though ICES MSVPA estimates of sandeel
consumption by fish predators are lower than our estimates, the reduced total
consumption would still lie perilously close to the total stock assessment. It would
appear that the food requirements of the North Sea animal kingdom are not being met
(at least in respect of sandeel).
POUT RESULTS:
Some 1.3 million tonnes of pout are consumed by North Sea human consumption fish
predators. It is interesting to note that the main predators of pout are haddock and
saithe of which the older fish of those species are concentrated in the northern part of
the North Sea where the main pout concentrations are found.
Haddock and pout are both widespread throughout the northern section of the
North Sea, north of 58°N latitude. Older cod are also mainly distributed in northern
waters but their intake of pout amounts to a smaller overall proportion of their diet.
The total stock biomass of pout in 1994 (this is the most recent year for which
a total is available) as calculated by ICES (Anon, 1996) is 2,590,065 tonnes in quarter
four of the year. The commercial industrial fishery accounts for 172,100 tonnes
(ACFM, 1994). In total, some 1,483,153 tonnes are taken for food by fish predators
and by the commercial fishery. This amounts to 57.3% of the total stock. It does not
include natural deaths (such as old age, disease, parasitism and accidental destruction
by trawl gear nor any consumption by mammals).
Evaluation of Ecological Effects of the North Sea
available on the western side along the English and Scottish coasts, on the Dogger
Bank and across the Dutch coast and northwards along the offshore Danish coast.
Whiting associate with the entire north-south length of the North Sea during
winter. They may well be taking advantage of the pout in northern parts during winter
months as well as sandeel, sprat and juvenile herring in southern parts over the whole
year.
TOTAL SANDEEL CONSUMPTION BY THE ANIMAL KINGDOM
Adding seabird consumption of, on average, 200,000 tonnes of sandeel per annum,
mammal outtake of 45,000 tonnes (both these estimates are taken from Anon, 1994;
the mammal consumption does not include that taken by the estimated 380,000
porpoise in the North Sea) and the commercial catch (as indicated in ICES ACFM
reports) to the consumption by fish predators gives a total consumption set out in Fig.
11. This is compared with the Spawning Stock Biomass and Total Stock Biomass
calculated by ICES for each year from 1976 to 1992. Apparently, total consumption of
sandeels equates to the total stock available. ICES do not place confidence limits to
their sandeel stock assessment and this may explain why our takeout plot lies higher
than the total stock for some years. Even though ICES MSVPA estimates of sandeel
consumption by fish predators are lower than our estimates, the reduced total
consumption would still lie perilously close to the total stock assessment. It would
appear that the food requirements of the North Sea animal kingdom are not being met
(at least in respect of sandeel).
POUT RESULTS:
Some 1.3 million tonnes of pout are consumed by North Sea human consumption fish
predators. It is interesting to note that the main predators of pout are haddock and
saithe of which the older fish of those species are concentrated in the northern part of
the North Sea where the main pout concentrations are found.
Haddock and pout are both widespread throughout the northern section of the
North Sea, north of 58°N latitude. Older cod are also mainly distributed in northern
waters but their intake of pout amounts to a smaller overall proportion of their diet.
The total stock biomass of pout in 1994 (this is the most recent year for which
a total is available) as calculated by ICES (Anon, 1996) is 2,590,065 tonnes in quarter
four of the year. The commercial industrial fishery accounts for 172,100 tonnes
(ACFM, 1994). In total, some 1,483,153 tonnes are taken for food by fish predators
and by the commercial fishery. This amounts to 57.3% of the total stock. It does not
include natural deaths (such as old age, disease, parasitism and accidental destruction
by trawl gear nor any consumption by mammals).