REVIEW OB THE SYSTEMATICS AND ECOLOGY OF OCEANIC SQUIDS
269
seen at the surface at night are various members of the Ommastrephidae
(pages 108, 115, 117).
Most species have been recorded from the stomachs of various
cetaceans, seals, fish and birds (Table VI). Many of these predators
eat squids almost exclusively while a large number eat varying proportions of fish in addition. Many species of squid which are important
in the diet of predators are rarely, if ever, caught by man-made collecting devices. For example, if it were not for the fact that large populations of Sperm whales mainly feed on such squids as Architeuthis,
Taningia, Lepidoteuthis, Histioteuthis, etc., these would be considered
extremely rare (Clarke, 1962a).
Large numbers of squid beaks have been reported in bottom sediments
and the largest quantities have been related to areas of productivity
(Belyaev, 1959, 1962; Clarke, 1962e). It was estimated that up to
15 000 beaks may be present on a square metre of bottom in some
areas (Belyaev, personal communication). The majority of such
beaks are very small and may represent larval mortalities.
Clearly, active carnivores like squids must have a terrific influence
on the balance of life in any area. The young seem to feed largely on
crustacea and small fish while the larger specimens take fish and
other squid. It has been suggested they have a direct effect, by predation, on certain commercial species of fish including redfish (Nesis,
1966), cod (Clarke, 1963), mackerel (Clarke, 1963) and herring (Fridriksson, 1943 etc.). They must also have an indirect effect by competing
with some commercial species for food; Nesis (1965) considered that
Qonatus fabricii competed with redfish in this way.
XXVIII. ECONOMIC IMPORTANCE
The economic importance of cephalopods in general may be seen
from Table VII. The catches tabulated are probably rather lower
than those actually taken because cephalopods are often excluded
from catch statistics. From the table there is some indication of a
rise in the importance of cephalopods. It is rather difficult to assess
the extent to which oegopsids contribute t o the catches. However,
nearly all squid taken in Japan, the country with the greatest consumption, are oegopsids including the local " common " squid Todarodes
paci$cus and Watasenia scintillans. Illex illecebrosus is the squid
most frequently taken off Newfoundland (Hodder, 1964) but only a
small proportion of those taken are given in statistics. Again, Madeira
where large catches are made, does not appear in statistics (unless it
is under Portugal) ; here the principal species caught are Ommastrephes
caroli, 0. pteropus and Todarodes sagittatus. In Norway Todarodes
269
seen at the surface at night are various members of the Ommastrephidae
(pages 108, 115, 117).
Most species have been recorded from the stomachs of various
cetaceans, seals, fish and birds (Table VI). Many of these predators
eat squids almost exclusively while a large number eat varying proportions of fish in addition. Many species of squid which are important
in the diet of predators are rarely, if ever, caught by man-made collecting devices. For example, if it were not for the fact that large populations of Sperm whales mainly feed on such squids as Architeuthis,
Taningia, Lepidoteuthis, Histioteuthis, etc., these would be considered
extremely rare (Clarke, 1962a).
Large numbers of squid beaks have been reported in bottom sediments
and the largest quantities have been related to areas of productivity
(Belyaev, 1959, 1962; Clarke, 1962e). It was estimated that up to
15 000 beaks may be present on a square metre of bottom in some
areas (Belyaev, personal communication). The majority of such
beaks are very small and may represent larval mortalities.
Clearly, active carnivores like squids must have a terrific influence
on the balance of life in any area. The young seem to feed largely on
crustacea and small fish while the larger specimens take fish and
other squid. It has been suggested they have a direct effect, by predation, on certain commercial species of fish including redfish (Nesis,
1966), cod (Clarke, 1963), mackerel (Clarke, 1963) and herring (Fridriksson, 1943 etc.). They must also have an indirect effect by competing
with some commercial species for food; Nesis (1965) considered that
Qonatus fabricii competed with redfish in this way.
XXVIII. ECONOMIC IMPORTANCE
The economic importance of cephalopods in general may be seen
from Table VII. The catches tabulated are probably rather lower
than those actually taken because cephalopods are often excluded
from catch statistics. From the table there is some indication of a
rise in the importance of cephalopods. It is rather difficult to assess
the extent to which oegopsids contribute t o the catches. However,
nearly all squid taken in Japan, the country with the greatest consumption, are oegopsids including the local " common " squid Todarodes
paci$cus and Watasenia scintillans. Illex illecebrosus is the squid
most frequently taken off Newfoundland (Hodder, 1964) but only a
small proportion of those taken are given in statistics. Again, Madeira
where large catches are made, does not appear in statistics (unless it
is under Portugal) ; here the principal species caught are Ommastrephes
caroli, 0. pteropus and Todarodes sagittatus. In Norway Todarodes