308
J. H. S. BLAXTER A N D F. 0. T. HOLLIDAS
changes in the proportions of intracellular water and proteins, but 110
measurements exist.
3. Skin thickness and composition
McBride et al. (1960) showed that sexually mature Clupea p a l h i i
caught in January had 40% more collagen in the body than immature
fish caught in June. The changes were found to be due almost entirely
to seasonal changes in collagen content of the skin and scales. Hughes
(personal communication) reported a similar finding in the herring, and
it would appear that collagen content of the skin is highest when the
subdermal fat content is lowest. Histological studies of the skin of these
herring showed a much greater thickness of skin in the early spring
than in the late summer.
4 . Changes in the blood
Naumov (1966) found that the haemoglobin content of the herring's
blood was highest (61-64%) during early maturation, but fell sharply
(to 43%) at spawning and in the spent stages. Percentage haemoglobin
increased with age and fatness. These changes may not represent actual
changes in either circulating erythrocytes or their individual haemoglobin content, for any increase in the plasma volume would lower the
percentage of haemoglobin per unit of blood. Estimations of blood
volume and haematocrit values are clearly needed. Naumov also
describes cyclical changes in the numbers and types of leucocytes with
gonad maturation.
Sindermann and Mairs (1959a) studied pre- and post-spawning
Pornolobus pseudoharengw (which ie anadromou) and found no change
in sedimentation rake, erythrocytr: fragility, tw:rnoglotjiri c:orrb:iit,
serum electrophoretic patterns hetween tbe two phawn of thf: lifc of t h o
fish. Sindermann (1958), Sindermann and Maim (1958, l!KiOL, 1940)
and itfairs and Sindermann (1960) studied the serology of Atlantic
clupeids and compared them with Oncorhyncus nerkn (the blue back).
They found that Pornolobus and Oncurhy~zce had a high degree of
serological correspondence. A h~a wttw clwit$r to thi: On.corhyrt.cu~ -
F'cmdobw complex than tr, ei thcr Iirevoortia or th: !wrrhg. '1'h
herring was furthest serologically from any of the other spccics studied.
These authors were able to use the serological properties of the blood
to differentiate between different stocks of the herring. Age appeared to
alter the serological patterns in the herring, as did disease. Sprague and
Vrooman (1962) studied the erythrocyte antigens in Sardinops caerulea
and found two systems of blood groups (indicating two reproductively
isolated groups).
J. H. S. BLAXTER A N D F. 0. T. HOLLIDAS
changes in the proportions of intracellular water and proteins, but 110
measurements exist.
3. Skin thickness and composition
McBride et al. (1960) showed that sexually mature Clupea p a l h i i
caught in January had 40% more collagen in the body than immature
fish caught in June. The changes were found to be due almost entirely
to seasonal changes in collagen content of the skin and scales. Hughes
(personal communication) reported a similar finding in the herring, and
it would appear that collagen content of the skin is highest when the
subdermal fat content is lowest. Histological studies of the skin of these
herring showed a much greater thickness of skin in the early spring
than in the late summer.
4 . Changes in the blood
Naumov (1966) found that the haemoglobin content of the herring's
blood was highest (61-64%) during early maturation, but fell sharply
(to 43%) at spawning and in the spent stages. Percentage haemoglobin
increased with age and fatness. These changes may not represent actual
changes in either circulating erythrocytes or their individual haemoglobin content, for any increase in the plasma volume would lower the
percentage of haemoglobin per unit of blood. Estimations of blood
volume and haematocrit values are clearly needed. Naumov also
describes cyclical changes in the numbers and types of leucocytes with
gonad maturation.
Sindermann and Mairs (1959a) studied pre- and post-spawning
Pornolobus pseudoharengw (which ie anadromou) and found no change
in sedimentation rake, erythrocytr: fragility, tw:rnoglotjiri c:orrb:iit,
serum electrophoretic patterns hetween tbe two phawn of thf: lifc of t h o
fish. Sindermann (1958), Sindermann and Maim (1958, l!KiOL, 1940)
and itfairs and Sindermann (1960) studied the serology of Atlantic
clupeids and compared them with Oncorhyncus nerkn (the blue back).
They found that Pornolobus and Oncurhy~zce had a high degree of
serological correspondence. A h~a wttw clwit$r to thi: On.corhyrt.cu~ -
F'cmdobw complex than tr, ei thcr Iirevoortia or th: !wrrhg. '1'h
herring was furthest serologically from any of the other spccics studied.
These authors were able to use the serological properties of the blood
to differentiate between different stocks of the herring. Age appeared to
alter the serological patterns in the herring, as did disease. Sprague and
Vrooman (1962) studied the erythrocyte antigens in Sardinops caerulea
and found two systems of blood groups (indicating two reproductively
isolated groups).