HERRING. 
965 
are nearly 400 fathoms of water. The continuation of 
the channel, up to. the 40-fathoms line, follows the 
west coast of Sweden south to about the latitude of 
Kongsbacka, i. e. as far as the true coast fishery for 
Great Herring has ever extended to the south in 
Sweden. 
To trace the Herring to its ocean home is a hope- 
less task. Conjecture must still play a prominent part 
in all opinions of its life in the depths. But so much 
is apparently clear, that its wanderings follow the de- 
pressions and steeps of the bottom. How deep it can 
descend, we know not; but the advanced development 
that it can descend to considerable depths, of some 
hundred fathoms at least, though probably not to the 
deepest parts of the Atlantic. 
As Mac Cullocii has remarked, the rovings of 
the Herring have three motive causes, the quest of a 
spawning-place, the chase of food, and the dread of 
its pursuing enemies. 
The spawning-season of the Herring lasts all the 
year round; but only a part of the wandering multi- 
tudes, in general those of the same age, are in breed- 
ing condition at the same time. Different spawning- 
seasons may hence characterize different localities, and 
KChrisUa/iia 
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fscox 
^EXGLAISTD / 
rN^Loridon 0 ( , 
0 100 fathoms 
100 -1000 - 
WOO -2000'- 
fesliMva over <000 
Scale 1 22,000000 
Fig. 241. The North-eastern Atlantic together with the North Sea and the Baltic. After 0. Torell. 
of the adipose membrane covering the head ranges it 
nearer than the Mackerel to the true deep-sea fishes. 
The pressure need not greatly distress the Herring, for 
only few fishes can so easily adapt the distension of 
the air-bladder to varying degrees of pressure. The 
lower temperature of the depths need not deter it, for 
fishes with so extensive a geographical range must by 
nature be accustomed to widely different temperatures, 
though the Herring seems sensitive to sudden varia- 
tions. The same may be said of the greater or less 
salinity of different layers of water. All that we know 
of the Herring’s nature well admits of the assumption 
in the same locality it is not uncommon to find two 
separate spawnings every year. In the Atlantic the 
two spawnings, where they occur, take place before and 
after the winter, in the Baltic before and after the 
summer. This applies to the main body of the shoals; 
but during the intervening periods isolated instances of 
breeding fish may be observed almost everywhere. As 
a rule the oldest Herrings spawn first, in the autumn, 
the younger ones later, when the spring has set in or 
in the summer. From the Gulf of Bothnia Gisler ad- 
duces the Spring or Ice Stromming, which spawns within 
the island-belt when the ice breaks up, the Net Strom- 
