344
J. H. 5. BLAXTER AND F. 0 . T. HOLLIDAY
of day and night. Brawn (1960b), in Passamaquoddy Bay, found no
relationship between mean solar radiation and the depth of shoals of
immature h e ~ i n g . Nomura (1 958) reported Sardinops melanosticta
sinking to a depth by day where the illumination was 10-1000 lux.
3. Ternperdure
Schubert (1950) reported that northern North Sea herring would not
migrate upwards through thermoclines of 6 deg. C in 3 m, but would
through 2 deg. C in 3 m. I n shallower depths herring were found to
Depth of upper IweI of herring shoals (lothorns)
FIO. 14. The dttpth of fiorririy W ~ O H I H rrt rliffiwmt. virrt,icd oxt,imt,H flf t h mtrfnen lrynr of
horriogonnoiin wator tornperatiiro. ( I t 0 drtrwn wiLh ~ i n r r i i i ~ ~ i i m
from l'orrtuma,
1067.)
0 1954
. 1 I ) X x 1057
remain below a thermocline of 2 cleg. C in 6 m. Richardson (1952)
found that herring passed upwards through a thermocline of 2.45 deg. C
in 6 m. Postuma (1957) showed that North Sea herring would not
migrate upwards beyond the point where the gradually rifling temperature ceased to rise (see Fig. 18). ThuA where there waH a deep layer of
water at the surface where the temperature wau homogeneous, the
herring remained deep. Solovyev and Uegtyarev (1057) found that
herring in tLe Viking Bank area would not move up into cold, lem d i n e
water of Baltic origin, and Devold (pmonal communication) found that
spawning Atlanto-Scandian herring would not move up into low mlirlity
J. H. 5. BLAXTER AND F. 0 . T. HOLLIDAY
of day and night. Brawn (1960b), in Passamaquoddy Bay, found no
relationship between mean solar radiation and the depth of shoals of
immature h e ~ i n g . Nomura (1 958) reported Sardinops melanosticta
sinking to a depth by day where the illumination was 10-1000 lux.
3. Ternperdure
Schubert (1950) reported that northern North Sea herring would not
migrate upwards through thermoclines of 6 deg. C in 3 m, but would
through 2 deg. C in 3 m. I n shallower depths herring were found to
Depth of upper IweI of herring shoals (lothorns)
FIO. 14. The dttpth of fiorririy W ~ O H I H rrt rliffiwmt. virrt,icd oxt,imt,H flf t h mtrfnen lrynr of
horriogonnoiin wator tornperatiiro. ( I t 0 drtrwn wiLh ~ i n r r i i i ~ ~ i i m
from l'orrtuma,
1067.)
0 1954
. 1 I ) X x 1057
remain below a thermocline of 2 cleg. C in 6 m. Richardson (1952)
found that herring passed upwards through a thermocline of 2.45 deg. C
in 6 m. Postuma (1957) showed that North Sea herring would not
migrate upwards beyond the point where the gradually rifling temperature ceased to rise (see Fig. 18). ThuA where there waH a deep layer of
water at the surface where the temperature wau homogeneous, the
herring remained deep. Solovyev and Uegtyarev (1057) found that
herring in tLe Viking Bank area would not move up into cold, lem d i n e
water of Baltic origin, and Devold (pmonal communication) found that
spawning Atlanto-Scandian herring would not move up into low mlirlity