HERRING. 
967 
states quite the opposite of Norway". When the spawn- 
ing begins, however, the sexes mingle promiscuously, 
and the operation is performed much in the same way 
as we have above described when treating of the Gwy- 
niads. Gisler tells in animated language how the Baltic 
Herring then approaches land in large and densely pack- 
ed shoals, often extending more than three-quarters of 
a mile along the coast, and always containing many 
times more females than males. The fish tumble about, 
and lash with their tails so violently that the scales drop 
off and float to the surface, in company with small air- 
bubbles which the Herrings emit. The sea is dyed gray, 
and a powerful and rank smell, appreciable at a great 
distance, fills the air. The spawning multitude does 
not shun the net, but rather presses willingly into its 
meshes. The operation does not last long, however, at 
the same spot, “probably no more than five or six hours”, 
according to Sundevall, when the shoal withdraws. 
Out at sea the spawning presents a similar sight: in a 
confused mass, gleaming with phosphorescent light, the 
fish toss about, near the surface when the night is dark 
and the 'weather mild; deeper in the water when there 
is moonlight and in frosty weather * 6 * 8 . The impregnated 
eggs sink to the bottom, and attach themselves to sea- 
weed, stones, shells, and other firm objects, or some- 
times cake together on the gravel or sand, or even on 
a clayey bottom. 
The number and size of the eggs vary, as usual, 
according to the size of the mother fish and their own 
degree of ripeness. Their number may be estimated at 
about 20,000 — 40,000 in different females; their size, 
when they are ripe and ready to be deposited, varies 
in the Baltic Herring 0 , generally speaking, between 0‘92 
(exceptionally 0'85) and 1 mm., in the North-Sea Her- 
ring between 1 and l'o mm/ Of the development we 
learn from Sundevall’s notes 0 that, “after the embryo 
had been formed, it was seen (in August) to turn in the 
egg seven or eight times a minute, subsequently more 
seldom, and latterly only once every two or three mi- 
nutes. The hatching generally takes place in a fort- 
night or a little more, but in water of a higher tem- 
perature, over + 20° C. (+ 68° Fahr.) for example, only 
three days are required/ As long as the fry retain the 
yolk (fig. 242), they move in a peculiar manner. By 
violently bending or tossing the body, an operation 
repeated every second, or at somewhat greater or less 
intervals, they work their way upwards, to the surface 
(at least when they are confined in vessels 3 — 6 dm. 
deep), and as soon as they have touched the surface, 
they keep still and sink again to the bottom, where 
they lie for a while, and then resume this upward mo- 
tion. — As soon as the yolk is absorbed, which takes a 
week’s time, they commence swimming in dense shoals, 
with a serpentine movement. The tins and the general 
shape of the body seemed to have attained their full 
development in the course of two or three months, 
when the fish is about 36 mm. long.” These remarks 
apply to the Spring Stromming. But so great may be 
Fig. 242. Newly hatched Baltic Herring, 7 nun. long, taken on the 
12th of May, 1854. C. J. Sundevall. 
the difference between the summer and winter growth 
that the Autumn Stromming, which develops during the 
colder months, requires in the Baltic, according to Mobius 
and Heincke, 7 — 9 months to attain the said degree of 
development 6 ', and has then grown to a length of more 
than 60 mm. The ventral tins are developed in the 
Spring Herring of the Baltic, according to Heincke 6 , 
when the fish is only 25 1 / 2 mm. long; but in the Autumn 
Herring they do not appear until the fish measures 
33 V 2 mm. The following comparison has been drawn 
by Meyer between the growth of the Spring Herring 
in the Baltic and that of young Trout: 
° 1. c., p. 26. 
6 For a description of the noisy spawning at sea, and how the Herring immediately after the operation quits the spawning-place, see 
Cuv., Val., 1. c., XX, p. 87. 
c Kupffer, Jahresb. Comm. Unt. D. Meere, Kiel 1874' — 76, p. 177. 
d According to Boeck, 1. e., 1*1 mm. 
e Om Fiskyngels utveckling , Vet.-Akad. Hand!., Bd. I (1855), p. 17. 
/ The- hatching takes place, according to Kupffer (1. c., p. 29), in water of a temperature between + 14° and + 19° C. within 6 — 
8 days; according to M&bius and Heincke ( Fisch Osts., p. 137), at a temperature of + 10° or + 11° C. in 11 days and at a temperature 
of + 7° or + 8° C. in 15 days. 
g According to Meyer (Comm. Deutsch. Meer. 1874 — 76, p. 248), however, small Autumn Herrings 45 — 60 mm. long and of almost 
perfect shape are found in February. 
h Comm., 1. c., p 128. 
Scandinavian Fishes. 
122 
