TIIE BEHAVIOUR AND PHYSIOLOGY OF HERRTNQ AND OTHER CIIJPE1T)S 3%
herring larvae suddenly increased when thc caudal fin developed.
Symmons (personal communication) has drawn attention to the presence
of a strong elastic longitudinal ligament ventral to, and in close aasociation with, the vertebral column of almost all clupeiform species.
Its skeletal importance has never been suggested before, but Symmons
believes it might be associated with fish having good powers of swimming and leaping. The ligament is probably capable of producing a
spring effect, making rapid movements of the tail more effective by a
side-to-side snapping action. She suggests that this is a source of potential energy which may account, in part, for the endurance of these fish.
P. Activity
The study of the levels of activity of clupeid fishes is becoming
It influences both
increasingly important to the fishery biologist.
fish location and fish capture.
1. Diurnal variations in activity
The intriguing problem of whether the herring ever ‘ I sleeps ” was
apparently solved by Radakov and Solovyev (1969) and Zaitsev and
Radakov (1960), who observed hcrring from a submarine. As night
fell the herring became motionless in the surface waters, remaining at
various angles to the horizontal ‘ I aa if drowsy ”. The fish became
increasingly active just before dawn, and in the early morning all
migrated down several hundred metres. If a searchlight was played on
the motionless herring, they became active and moved away from the
beam.
Blaxter et al. (1960) found that at night hwririg w w : riot t i f ~ r M lry
towed ropes, or even underwater lights (though young herring may he
attracted by artificial lights). It would appear that the physiological
state of the herring is different by day and night.
2. Control of activity
Parry and Holliday (1960) and Holliday and Parry (1962) suggested
that the pseudobranch in fishes controlled their activity by governing
in some way the availability of oxygen to the fish and it8 utilization at
the tissues. Removal of the pseudobranch8 rewltcd in a reduction in
metabolism coupled with an ability to survivo in conditiona of oxygm
lack, fatal to normal fish. The pseudobranch waH linked hy itfi I h r d
system to the choroid gland of the eye, wherc it, could t j c oontroll~:~l hy
the amount of light falling on the retina. ‘I’hiH Hyntr:rn might oxplairl
diurnal variations in thc activity of fhh.
herring larvae suddenly increased when thc caudal fin developed.
Symmons (personal communication) has drawn attention to the presence
of a strong elastic longitudinal ligament ventral to, and in close aasociation with, the vertebral column of almost all clupeiform species.
Its skeletal importance has never been suggested before, but Symmons
believes it might be associated with fish having good powers of swimming and leaping. The ligament is probably capable of producing a
spring effect, making rapid movements of the tail more effective by a
side-to-side snapping action. She suggests that this is a source of potential energy which may account, in part, for the endurance of these fish.
P. Activity
The study of the levels of activity of clupeid fishes is becoming
It influences both
increasingly important to the fishery biologist.
fish location and fish capture.
1. Diurnal variations in activity
The intriguing problem of whether the herring ever ‘ I sleeps ” was
apparently solved by Radakov and Solovyev (1969) and Zaitsev and
Radakov (1960), who observed hcrring from a submarine. As night
fell the herring became motionless in the surface waters, remaining at
various angles to the horizontal ‘ I aa if drowsy ”. The fish became
increasingly active just before dawn, and in the early morning all
migrated down several hundred metres. If a searchlight was played on
the motionless herring, they became active and moved away from the
beam.
Blaxter et al. (1960) found that at night hwririg w w : riot t i f ~ r M lry
towed ropes, or even underwater lights (though young herring may he
attracted by artificial lights). It would appear that the physiological
state of the herring is different by day and night.
2. Control of activity
Parry and Holliday (1960) and Holliday and Parry (1962) suggested
that the pseudobranch in fishes controlled their activity by governing
in some way the availability of oxygen to the fish and it8 utilization at
the tissues. Removal of the pseudobranch8 rewltcd in a reduction in
metabolism coupled with an ability to survivo in conditiona of oxygm
lack, fatal to normal fish. The pseudobranch waH linked hy itfi I h r d
system to the choroid gland of the eye, wherc it, could t j c oontroll~:~l hy
the amount of light falling on the retina. ‘I’hiH Hyntr:rn might oxplairl
diurnal variations in thc activity of fhh.