356
J. H. 5. BLAXTER AND F. 0 . T. HOLLIDAY
X. Haturation of the gonads
1. Maturity scales
The assessmeiit of sexual maturity has been for some time part of
the routine sampling of herring populations by fisheries workers.
Gonads are classified into arbitrary maturity stages (I, 11, 111, etc.),
by estimation of such criteria as the shape and colour of the gonad, its
size in relation to that of the body cavity, size of eggs, etc. The classification of Hjort (1910) was (with slight modifications) recommended
for general adoption by the International Council for the Exploration of
the Sea (Ehrenbaum, 1930). Jensen (1950) discussed the relative
merits of the international scale, and that proposed by Johansen (1919)
which was used for a while by Danish fishery biologists. Naumov
(1956) discussed another scale in relation to fecundity and ovarian
development. More recently Heincke’s (1898) scale (modified by
Aasen, 1952) has been suggested as being preferable to the Hjort scale,
in that it allows closer distinctions to be made between stages.
2. Morphology
The general gonad morphology and gross micro-anatomy was
described in the herring by Cunningham (1896), Hjort (1910), Bullough
(1940) and Williamson (1945).
3. Histological changes during maturation
Naumov (1956), Polder (1961) and Bowers and Holliday (1961)
independently published detailed accounts of the herring gonad.
Andrews (unpublished) gave a similar account for Rardinop cuerulea
and Andreu and dos Santos Knto (IU57) arid (JOH ~ I L l l f A J H I’irif,o (IV57)
for Sardina pilchardus. ‘I’ho herring tias n total qmwrririg, i.c. all the
developirig eggs mature us or10 l ~ ~ t e I i
uiid aro spawnetl together. In
A9urtlinops ctiwuletc and Sarrlinn pilrhardus the eggs arc produced and
rc1casc.d in siicccssivc crops throughout the scasoii. The general
rlevolopinent is, however, aplmrcxitly the same for all clupcids.
(a) The testis. The germ cells dcvelop in a system of coiinectivo tiseue
tubules (see Fig. 19), these tubules being lined with connective tissue
cells which may function as Sertoli cells. Figure 20 summarizes the
changes in the relative occurrence of the germ cells at each stage of
development in the herring. The increase in size of the testes is brought
about by the rapid,increa,se in total numhcr of germ crdh in the gonad.
Spermatozoa, first appear at Stage I I (Fig, 21). .Jwt prior 1.11 npiwrhrg
(Stage VI) the tuhulks are packed with Hprrn ; aftfir Hpiiwitirtg htw
tubules shrink as the conncctivc tiwue contractn. I’ltrlict, nporrn arr.
J. H. 5. BLAXTER AND F. 0 . T. HOLLIDAY
X. Haturation of the gonads
1. Maturity scales
The assessmeiit of sexual maturity has been for some time part of
the routine sampling of herring populations by fisheries workers.
Gonads are classified into arbitrary maturity stages (I, 11, 111, etc.),
by estimation of such criteria as the shape and colour of the gonad, its
size in relation to that of the body cavity, size of eggs, etc. The classification of Hjort (1910) was (with slight modifications) recommended
for general adoption by the International Council for the Exploration of
the Sea (Ehrenbaum, 1930). Jensen (1950) discussed the relative
merits of the international scale, and that proposed by Johansen (1919)
which was used for a while by Danish fishery biologists. Naumov
(1956) discussed another scale in relation to fecundity and ovarian
development. More recently Heincke’s (1898) scale (modified by
Aasen, 1952) has been suggested as being preferable to the Hjort scale,
in that it allows closer distinctions to be made between stages.
2. Morphology
The general gonad morphology and gross micro-anatomy was
described in the herring by Cunningham (1896), Hjort (1910), Bullough
(1940) and Williamson (1945).
3. Histological changes during maturation
Naumov (1956), Polder (1961) and Bowers and Holliday (1961)
independently published detailed accounts of the herring gonad.
Andrews (unpublished) gave a similar account for Rardinop cuerulea
and Andreu and dos Santos Knto (IU57) arid (JOH ~ I L l l f A J H I’irif,o (IV57)
for Sardina pilchardus. ‘I’ho herring tias n total qmwrririg, i.c. all the
developirig eggs mature us or10 l ~ ~ t e I i
uiid aro spawnetl together. In
A9urtlinops ctiwuletc and Sarrlinn pilrhardus the eggs arc produced and
rc1casc.d in siicccssivc crops throughout the scasoii. The general
rlevolopinent is, however, aplmrcxitly the same for all clupcids.
(a) The testis. The germ cells dcvelop in a system of coiinectivo tiseue
tubules (see Fig. 19), these tubules being lined with connective tissue
cells which may function as Sertoli cells. Figure 20 summarizes the
changes in the relative occurrence of the germ cells at each stage of
development in the herring. The increase in size of the testes is brought
about by the rapid,increa,se in total numhcr of germ crdh in the gonad.
Spermatozoa, first appear at Stage I I (Fig, 21). .Jwt prior 1.11 npiwrhrg
(Stage VI) the tuhulks are packed with Hprrn ; aftfir Hpiiwitirtg htw
tubules shrink as the conncctivc tiwue contractn. I’ltrlict, nporrn arr.