THE BEK~VIOUR AXD PHYSIOLOOY OF HERRWQ AND OTHER CLUPEIDS 371
salinities, and the tolerant eggs and larvae can survive in marine,
littoral, estuarine and in some caws freshwater conditions. They me,
however, well adapted to a pelagic, shoaling mode of life-mechanically,
hydrodynamically, as well as in the biochemical composition and
potential activity level of their tissues. Although they depend on a
fluctuating food supply, the ability to store fat enables them to survive
at all seasons. Presumably this adaptability has led to the formation of
the complex racial system.
Clupeids are found in large numbers despite the level of predation to
which they are subjected. Presumably the advantages of shoaling far
outweigh the disadvantages. Relatively low fecundity does not seem
to have been a handicap and this is true where the egg is dememl, as
well as where it is pelagic. Nor does a small egg, with little yolk and a
small larva dependent on external food soon after hatching, appear to
be a disadvantage. The size of a spawning stock seems to have little
effect on the subsequent year class strength, so that egg potential does
not appear to be in any way limiting. What determines the year class
strength, in herring at least, remains a mystery, and yet the fluctuations
can be large.
Unfortunately, many other aspects of the herring basic biology
remain a mystery-in particular its means of migration, the control of
its reproductive processes and the interrelationship between different
races and the extent to which flow may take place between them.
Other problems which have scarcely been touched on are the role of
olfactory and auditory stimuli and the function of the complex lateral
line in the life of clupeids, and the advantage of the soft body and
deciduous scales to their survival.
One aspect of specialization iu thc apparent d o m i n ~ n m ~
of v i k i
among the other senses. It seems to be the sense uaed beforo all othcrs
in feeding, shoaling, spawning and escape.
It is interesting to speculate upon the evolutionary position of the
clupeids. Even the accepted marine species, Ruch as the herring, have
some associations with a freshwater way of life. This is shown in
serological, biochemical and anatomical correspondences with freshwater fishes, as well as in certain aspects of behaviour, such as demersal
spawning. It seems most likely that the teleosts originated in fresh water
and that the clupeids have retained stronger links with their origins
than have other teleosts ; perhaps this is due to a much more recent
colonization of the sea,
It has become clearer in the past few years that fisheries problem8
cannot be solved without a better knowledge of behaviour and phywiOlogy. This has been emphasized by Hardy (1949) and Bull (1061).
25
salinities, and the tolerant eggs and larvae can survive in marine,
littoral, estuarine and in some caws freshwater conditions. They me,
however, well adapted to a pelagic, shoaling mode of life-mechanically,
hydrodynamically, as well as in the biochemical composition and
potential activity level of their tissues. Although they depend on a
fluctuating food supply, the ability to store fat enables them to survive
at all seasons. Presumably this adaptability has led to the formation of
the complex racial system.
Clupeids are found in large numbers despite the level of predation to
which they are subjected. Presumably the advantages of shoaling far
outweigh the disadvantages. Relatively low fecundity does not seem
to have been a handicap and this is true where the egg is dememl, as
well as where it is pelagic. Nor does a small egg, with little yolk and a
small larva dependent on external food soon after hatching, appear to
be a disadvantage. The size of a spawning stock seems to have little
effect on the subsequent year class strength, so that egg potential does
not appear to be in any way limiting. What determines the year class
strength, in herring at least, remains a mystery, and yet the fluctuations
can be large.
Unfortunately, many other aspects of the herring basic biology
remain a mystery-in particular its means of migration, the control of
its reproductive processes and the interrelationship between different
races and the extent to which flow may take place between them.
Other problems which have scarcely been touched on are the role of
olfactory and auditory stimuli and the function of the complex lateral
line in the life of clupeids, and the advantage of the soft body and
deciduous scales to their survival.
One aspect of specialization iu thc apparent d o m i n ~ n m ~
of v i k i
among the other senses. It seems to be the sense uaed beforo all othcrs
in feeding, shoaling, spawning and escape.
It is interesting to speculate upon the evolutionary position of the
clupeids. Even the accepted marine species, Ruch as the herring, have
some associations with a freshwater way of life. This is shown in
serological, biochemical and anatomical correspondences with freshwater fishes, as well as in certain aspects of behaviour, such as demersal
spawning. It seems most likely that the teleosts originated in fresh water
and that the clupeids have retained stronger links with their origins
than have other teleosts ; perhaps this is due to a much more recent
colonization of the sea,
It has become clearer in the past few years that fisheries problem8
cannot be solved without a better knowledge of behaviour and phywiOlogy. This has been emphasized by Hardy (1949) and Bull (1061).
25