322
J. H. 9. BLAXTER AND F. 0. T. HOLLIDAY
and thought that the value obtained by Magnan was high due to loss
of gas from the swim bladder. Brawn (1960s) watched by television
the behaviour of herring lowered and raised in an underwater oage, and
found that descent seemed to be mainly by sinking. Presumably to
d o this they would have to be dense to start with, this density and the
speed' of descent increasing as the swim bladder became compreaeed,
unless there was some compensation by the swim bladder.
2. Equilibrium*
Fat deposits are such (Foster, quoted by Love, 1967) that there is
n o difference in buoyancy of the head and tail regions which might give
equilibrium difficulties. Maintenance of equilibrium is presumably by
mema of the labyrinth, but a dorsal light reaction may also be present.
Clupeida kept in aquaria often start to swim vertically when the light
is reduced to a low level, this being later compensated for ; Loukashkin
a n d Grant (1959) reported this in Surdimps caerulea, and Radakov and
Solovyev (1959) and Zaitsev and Radakov (1960) observed herring by
night from a submarine to be sometimes vertical.
0. Swimming
1. Rheotaxia and swimming ability
The ability of clupeids to stem currents is well known, but it Seems
that this depends on the presence of visual or tactile reference points
(Brawn, 1960a). She showed that herring 15-30 cm long, kept in an
underwater cage and watched by television, ceased to swim against the
current at low light intensities. Jones (1962) a h questioned the
ability of herring shoals in mid-water to stem currents, although it
might be possible in a deep shoal for the fish near the bottom to act &B
markers for other fish above them. His observations on the movements
of herring in relation to tide were not conclusive enough to show whether
the stemming was maintained in darkness after the fish lefi the bottom.
The maximum and cruising speeds of some clupeida have been
measured. Blaxter and Dickson (1959) found that captive herring
ranging from 1-26 cm swam at speeds (for distances at leaat ten times
their body length) of 2-200 cm/sec (temperature 6-18OC). Herring
20-25 cm long could swim at near their maximum speed for 1000
lengths. Brawn (1960a) (as part of the recent Paasamaquoddy herring
investigations) used freshly caught fish in the underwater cage, which
W a a towed by a research vessel, and found that herring 15-27 cm long
at ll-12°C had maximum speeds of 90-143 cm/sec (maintained by 60%
Sea sleo Section VI, Q.
J. H. 9. BLAXTER AND F. 0. T. HOLLIDAY
and thought that the value obtained by Magnan was high due to loss
of gas from the swim bladder. Brawn (1960s) watched by television
the behaviour of herring lowered and raised in an underwater oage, and
found that descent seemed to be mainly by sinking. Presumably to
d o this they would have to be dense to start with, this density and the
speed' of descent increasing as the swim bladder became compreaeed,
unless there was some compensation by the swim bladder.
2. Equilibrium*
Fat deposits are such (Foster, quoted by Love, 1967) that there is
n o difference in buoyancy of the head and tail regions which might give
equilibrium difficulties. Maintenance of equilibrium is presumably by
mema of the labyrinth, but a dorsal light reaction may also be present.
Clupeida kept in aquaria often start to swim vertically when the light
is reduced to a low level, this being later compensated for ; Loukashkin
a n d Grant (1959) reported this in Surdimps caerulea, and Radakov and
Solovyev (1959) and Zaitsev and Radakov (1960) observed herring by
night from a submarine to be sometimes vertical.
0. Swimming
1. Rheotaxia and swimming ability
The ability of clupeids to stem currents is well known, but it Seems
that this depends on the presence of visual or tactile reference points
(Brawn, 1960a). She showed that herring 15-30 cm long, kept in an
underwater cage and watched by television, ceased to swim against the
current at low light intensities. Jones (1962) a h questioned the
ability of herring shoals in mid-water to stem currents, although it
might be possible in a deep shoal for the fish near the bottom to act &B
markers for other fish above them. His observations on the movements
of herring in relation to tide were not conclusive enough to show whether
the stemming was maintained in darkness after the fish lefi the bottom.
The maximum and cruising speeds of some clupeida have been
measured. Blaxter and Dickson (1959) found that captive herring
ranging from 1-26 cm swam at speeds (for distances at leaat ten times
their body length) of 2-200 cm/sec (temperature 6-18OC). Herring
20-25 cm long could swim at near their maximum speed for 1000
lengths. Brawn (1960a) (as part of the recent Paasamaquoddy herring
investigations) used freshly caught fish in the underwater cage, which
W a a towed by a research vessel, and found that herring 15-27 cm long
at ll-12°C had maximum speeds of 90-143 cm/sec (maintained by 60%
Sea sleo Section VI, Q.