THE BEHAVIOUT AND PHYSIOLOGY OF HERRING AND OTHER CLUPEIDS 297
4. Effect of inter& factors on feeding
Williamson (1917) found that “ hungry ” herring were less easy to
frighten and would feed better. It has often been said that spawning
herring c e m to fecd, but sometimos they have becn found with food
in the gut-even herring eggs, which suggests feeding at some time
during the mass spawning act, for herring do not appear to take food
off the bottom.
The importance of psychological stimuli in feeding or initiating
feeding is mentioned in Section VI, A, where it is seen that the presence
of feeding f%h, not necessarily of the =me species, is a great incentive
to feeding.
6. Competition for food
Variations in growth rate of clupeids kept in aquaria suggest the
importance of dominant feeders, or of fish with more efficient utilization of food (see Section VI, E). But apart from intra-specific competition of this sort, about which practically nothing is known, there are
indications of negative correlations between the abundance of related
clupeid species in the same area. There have been changes in the
dominant species recently, but whether these are reversible or not
remains to be seen. Such correlations were discussed by MacGregor
(1959) and Marr (1961) for Sardinops eaerulea and Engraulis mordaz,
for Clupea pallusii and Sardinops melunosticta by Motoda and Hirano
(1961), and for Clupea harengus and Sardina pilchardus by Cushing
(1961). One possible explanation for these fluctuations could be
competition for food, but the extent to which long-term changes in
hydrographical conditions are responsihlo in not clear. It, rnrty t i c of
significance that these changes occur near the extrcmw of thr: rnrigc of
these species, where changes in hydrographical conditiorin m i g h t I)(:
expected to exert the maximum effect. hcr:ntly SOlJth WJLrfl I I ! N l )
has suggested that the increase of Sardinu pilchrlrdw arid dw:rww of
herring described by Cushing (1061) might be due to long-torm temperature charlgcs which put the herring at a disadvantage frorrl the
point of view of metabolism.
C. The alimentary system
I . Morphalqpy ( i d (inntom?/
Jmolwhqpi ( I !)13) dcscribcd tho hcrring intestine as being short
(one-half to thrcc-quarters the body length) and associated this fact
with the carnivorous diet of the fish. Herder (1960) compared gut
morphology with body form, food and environment in forty-six
4. Effect of inter& factors on feeding
Williamson (1917) found that “ hungry ” herring were less easy to
frighten and would feed better. It has often been said that spawning
herring c e m to fecd, but sometimos they have becn found with food
in the gut-even herring eggs, which suggests feeding at some time
during the mass spawning act, for herring do not appear to take food
off the bottom.
The importance of psychological stimuli in feeding or initiating
feeding is mentioned in Section VI, A, where it is seen that the presence
of feeding f%h, not necessarily of the =me species, is a great incentive
to feeding.
6. Competition for food
Variations in growth rate of clupeids kept in aquaria suggest the
importance of dominant feeders, or of fish with more efficient utilization of food (see Section VI, E). But apart from intra-specific competition of this sort, about which practically nothing is known, there are
indications of negative correlations between the abundance of related
clupeid species in the same area. There have been changes in the
dominant species recently, but whether these are reversible or not
remains to be seen. Such correlations were discussed by MacGregor
(1959) and Marr (1961) for Sardinops eaerulea and Engraulis mordaz,
for Clupea pallusii and Sardinops melunosticta by Motoda and Hirano
(1961), and for Clupea harengus and Sardina pilchardus by Cushing
(1961). One possible explanation for these fluctuations could be
competition for food, but the extent to which long-term changes in
hydrographical conditions are responsihlo in not clear. It, rnrty t i c of
significance that these changes occur near the extrcmw of thr: rnrigc of
these species, where changes in hydrographical conditiorin m i g h t I)(:
expected to exert the maximum effect. hcr:ntly SOlJth WJLrfl I I ! N l )
has suggested that the increase of Sardinu pilchrlrdw arid dw:rww of
herring described by Cushing (1061) might be due to long-torm temperature charlgcs which put the herring at a disadvantage frorrl the
point of view of metabolism.
C. The alimentary system
I . Morphalqpy ( i d (inntom?/
Jmolwhqpi ( I !)13) dcscribcd tho hcrring intestine as being short
(one-half to thrcc-quarters the body length) and associated this fact
with the carnivorous diet of the fish. Herder (1960) compared gut
morphology with body form, food and environment in forty-six