THE BEHAVIOUR AND PRYSI0u)OY OF HERRIXO AND OTHER CLUPEIDS 339
In species other than herring correlations have been found, perticdimly between temperature and fish concentrations. Hela and
Lwvaatu (1962) reported Russian work in the Bdtio showing how
Spattm eprattus was mainly caught in summer in water of 10-15"C, and
Japanese workers showed that the best catches of S a r d i q s rnelanoetii% on southern grounds were made where the surface temperature
ranged from 12-16°C. Pavshtika (1966) quoted Russian work where
this species was found to delay its spawning migration if food was
abundant. Phillips and Radovich (1962) elso reported that the distribution of Sardinups caerulea was correlated with temperature.
Hourston (1963) collected data showing that Clupea p l h i i was found
in less saline water off the Britieh Columbia coast.
It seems possible, too, that long-term hydrographical changes may
affect the distribution of fish on a more permanent basis. Devold (1961),
for example, has shown that the annual migration to the Norwegian
c m t of the Norwegian herring is becoming progreseively later eaoh
year. He suggested that this might ultimately bring the fish into suoh
different environmental conditions for a given stage in the life cyole
that the spawning time miFht be radically altered (thie is also d i s c d
under Section VI, X). Motoda and Hirano (1961) reported on long-term
temperature changes (and reviewed similar reports &om the eaetern
Pacific) affecting the distribution of the spawning of Clupea pallaaii.
Such hydrographical changes also seem to have affected the distribution
and spawning of Sardinup8 caerulea (Murphy, 1961). It is clew that
temprature changes on a long-term basis may not only affect distribution of fish by putting certain, formerly colonized areas " out of
bounds ", but may also affect growth, maturation and time of fir&
maturity (see Section VI, X).
The mechanism of aggregation in areas of favourable conditiom
might be explained on the theory of the kinesk, tho AAh tanding to move
lees in favoured arcaR, ctnd moro rapidly in arms which are unfavourablo.
In the case of feeding the shoals would, in any caso, tend to break and
slow down to allow the fish to feed. It is not clear whether such
mechanisms could account for the total migration pattern observed in
the life cycle. Could, for instance, tho movement of northern North
See herring from the edge of the Norwegian deeps to the feeding
grounds, the westward and then southward movement to the spawning
grounds, and the eastward drift after spawning, be only the result of a
series of kineses? It is possible that the herring might be prevented from
leaving the North Sea by unfavourable Atlantic water end from further
westward movement by the land mass of Scotland. With an Urge to
move, they would then turn muth or east to a favourable substratum
23
In species other than herring correlations have been found, perticdimly between temperature and fish concentrations. Hela and
Lwvaatu (1962) reported Russian work in the Bdtio showing how
Spattm eprattus was mainly caught in summer in water of 10-15"C, and
Japanese workers showed that the best catches of S a r d i q s rnelanoetii% on southern grounds were made where the surface temperature
ranged from 12-16°C. Pavshtika (1966) quoted Russian work where
this species was found to delay its spawning migration if food was
abundant. Phillips and Radovich (1962) elso reported that the distribution of Sardinups caerulea was correlated with temperature.
Hourston (1963) collected data showing that Clupea p l h i i was found
in less saline water off the Britieh Columbia coast.
It seems possible, too, that long-term hydrographical changes may
affect the distribution of fish on a more permanent basis. Devold (1961),
for example, has shown that the annual migration to the Norwegian
c m t of the Norwegian herring is becoming progreseively later eaoh
year. He suggested that this might ultimately bring the fish into suoh
different environmental conditions for a given stage in the life cyole
that the spawning time miFht be radically altered (thie is also d i s c d
under Section VI, X). Motoda and Hirano (1961) reported on long-term
temperature changes (and reviewed similar reports &om the eaetern
Pacific) affecting the distribution of the spawning of Clupea pallaaii.
Such hydrographical changes also seem to have affected the distribution
and spawning of Sardinup8 caerulea (Murphy, 1961). It is clew that
temprature changes on a long-term basis may not only affect distribution of fish by putting certain, formerly colonized areas " out of
bounds ", but may also affect growth, maturation and time of fir&
maturity (see Section VI, X).
The mechanism of aggregation in areas of favourable conditiom
might be explained on the theory of the kinesk, tho AAh tanding to move
lees in favoured arcaR, ctnd moro rapidly in arms which are unfavourablo.
In the case of feeding the shoals would, in any caso, tend to break and
slow down to allow the fish to feed. It is not clear whether such
mechanisms could account for the total migration pattern observed in
the life cycle. Could, for instance, tho movement of northern North
See herring from the edge of the Norwegian deeps to the feeding
grounds, the westward and then southward movement to the spawning
grounds, and the eastward drift after spawning, be only the result of a
series of kineses? It is possible that the herring might be prevented from
leaving the North Sea by unfavourable Atlantic water end from further
westward movement by the land mass of Scotland. With an Urge to
move, they would then turn muth or east to a favourable substratum
23