REVIEW OF THE SYSTEMATICS AND ECOLOGY OF OCEANIC SQUIDS
129
west coasts of Iceland in June or early July and by August enormous
ehoals are often found in the fjords of the north west where they
remain until November (Fridriksson, 1943). During September and
October at night there are great shoals near the surface but in November
they withdraw into the deeper part of the fjords. The inshore movement is thought to be in pursuit of fish and principally herring, because
the stomachs contain herring scales with one to seven winter rings on
them (Fridriksson, 1943). During the inshore period large numbers are
stranded (Bruun, 1945). I n the Faroes the species is often found in
very large numbers inshore in autumn (March, 1867). On the west
Norwegian coast, where they are sometimes so numerous that the sea,
has been described as “aboil” with them (Rustad, 1952), there is a,
periodicity in their appearance which seems to be related to the catches
of herring (Grieg, 1933b). In most years only a few are found on
Scottish coasts, but sometimes very large shoals appear and they may
be stranded in thousands (Stephen, 1937; 1944; Elmhirst, 1938; Gillespie, 1953). Various theories have been advanced to account for the
strandings (Ritchie, 1920a; Gillespie, 1953) but no real evidence in
support of any of these has been advanced. Kaas et al. (1940) found they
were more numerous in spring off the Netherlands. Mangold-Wirz
(196313) found no evidence for annual migrations in the Catalonian
Sea. However, in the Atlantic it enters the fishing grounds round
Madeira in large numbers during March, April and May (Rees and
Maul, 1956).
The species comes to the surface at night but apparently prefers to
stay on the bottom in daylight (Fridriksson, 1943; Mangold-Wirz,
1963b) where it is caught with trawls at depths between 70-800 m
(Naef, 1923; Grieg, 193313; Adam, 1939b; Dieuzeide, 1950; Moral-,
1958 ; Mangold-Wirz, 196313) and in the Catalonian Sea it has a preference for a depth of 400-700 m. (Mangold-Wirz, 196313). Evidence
from underwater photographs suggests that the species extends down
to at least 1 000 m (Table 11, p. 109).
It sometimes leaps to a considerable height above the water surface
(Sykes, 1833; Aratara, 1954).
Naef (1923) has figured a rhynchoteuthis larva purported to belong
to this species.
Relative growth involves no sudden changes in form. Growth in
time has been examined by Fridriksson (1943) who found that, off
Iceland, the mean mantle length on 17 July was 17.5 cm, on 3 August
it was 21.8 cm, on 8 September it was 28.0 cm and on 14 October it was
31.3 cm (Fig. 18 p. 138). This gave growth increments in each 30 days
of 7.6, 5.2 and 2.8 cm. He assumed that all these immature specimens
129
west coasts of Iceland in June or early July and by August enormous
ehoals are often found in the fjords of the north west where they
remain until November (Fridriksson, 1943). During September and
October at night there are great shoals near the surface but in November
they withdraw into the deeper part of the fjords. The inshore movement is thought to be in pursuit of fish and principally herring, because
the stomachs contain herring scales with one to seven winter rings on
them (Fridriksson, 1943). During the inshore period large numbers are
stranded (Bruun, 1945). I n the Faroes the species is often found in
very large numbers inshore in autumn (March, 1867). On the west
Norwegian coast, where they are sometimes so numerous that the sea,
has been described as “aboil” with them (Rustad, 1952), there is a,
periodicity in their appearance which seems to be related to the catches
of herring (Grieg, 1933b). In most years only a few are found on
Scottish coasts, but sometimes very large shoals appear and they may
be stranded in thousands (Stephen, 1937; 1944; Elmhirst, 1938; Gillespie, 1953). Various theories have been advanced to account for the
strandings (Ritchie, 1920a; Gillespie, 1953) but no real evidence in
support of any of these has been advanced. Kaas et al. (1940) found they
were more numerous in spring off the Netherlands. Mangold-Wirz
(196313) found no evidence for annual migrations in the Catalonian
Sea. However, in the Atlantic it enters the fishing grounds round
Madeira in large numbers during March, April and May (Rees and
Maul, 1956).
The species comes to the surface at night but apparently prefers to
stay on the bottom in daylight (Fridriksson, 1943; Mangold-Wirz,
1963b) where it is caught with trawls at depths between 70-800 m
(Naef, 1923; Grieg, 193313; Adam, 1939b; Dieuzeide, 1950; Moral-,
1958 ; Mangold-Wirz, 196313) and in the Catalonian Sea it has a preference for a depth of 400-700 m. (Mangold-Wirz, 196313). Evidence
from underwater photographs suggests that the species extends down
to at least 1 000 m (Table 11, p. 109).
It sometimes leaps to a considerable height above the water surface
(Sykes, 1833; Aratara, 1954).
Naef (1923) has figured a rhynchoteuthis larva purported to belong
to this species.
Relative growth involves no sudden changes in form. Growth in
time has been examined by Fridriksson (1943) who found that, off
Iceland, the mean mantle length on 17 July was 17.5 cm, on 3 August
it was 21.8 cm, on 8 September it was 28.0 cm and on 14 October it was
31.3 cm (Fig. 18 p. 138). This gave growth increments in each 30 days
of 7.6, 5.2 and 2.8 cm. He assumed that all these immature specimens