6 
but it soon separates and permeates the water to such extent that the water 
becomes opaque. When the spawning of a large number takes place at the 
same time the opaque area may reach for miles, so dense that the herring darting 
through the water, even when only a few inches from the surface of the water, 
appear but as shadows and if they are down a couple of feet they will not be 
seen at all. 
As the herring spawn somewhere in the vicinity of the Biological Station 
every year there has been plenty of opportunity for observation, and during 
several seasons a careful watch was kept over certain of these spawning areas. 
The herring do not spawn in the same place season after season as some other 
fish apparently do. A thorough survey of the spawning grounds of one year 
may be of no assistance in finding the spawning grounds of the next year. While 
the areas of one year may overlap the areas of another year I have never known 
them to correspond exactly in two succeeding years. 
In a previous paper! some description of the spawning areas was given, but 
further observation has shown that the matter is not so simple as at first it 
seemed. The spawning dates for different areas were quite correct, but it was 
not realized that at times spawning takes place day after day for a considerable 
period; it may take place for a number of days in succession, cease for a short 
time and then begin again, or it may take place over a short period only, even 
for a single day. The longest period, day after day, recorded, extended from 
March 19 to April 5, 1916. This was around Horswell rock, at the northern 
entrance to Departure Bay. 
Where spawning takes place in the same area day after day the spawning is 
by no means continuous. It seldom occurred outside of the period between 
12 noon and 5 p.m. The height of the tide evidently had nothing to do with it 
as the spawning was at its height at different times of the tide each day. On 
this account, since the spawn is always deposited in shallow water, usually less 
than 6 feet, much of that which is deposited at high tide is left exposed for some 
hours at low tide, particularly at spring tide. These exposures seem to do no 
harm, unless there is too much bright sun during the exposure. As the majority 
of really low tides come at night during that season such a thing seldom happens. 
It is not for lack of seaweed areas at greater depths that the shallow water 
is used, as it often happens that the bottom at a little greater depth is much 
more densely covered than the bottom near shore. 
After spawning is over the herring are in no hurry to leave the shallow water. 
They have been seen in Departure Bay in intervals during April and May, and 
this year a small school stayed around continuously until the end of June. 
The dangers of the deep water must be great if they are much greater than 
the dangers of the shore and shallow water. While the herring are spawning 
they are naturally not so active as at ordinary times and hence they fall a prey 
to their enemies the more readily. As they are so near the surface the gulls 
can see them and reach them readily. Since there are myriads of these they 
must cause the disappearance of innumerable herring just at the time when 
protection is most needed. The dogfish, doubtless their enemies at all times, 
1On Clupea pallasii Cuvier and Valenciennes. Trans. Royal Can. Inst., 1916, p, 97-108, 
108 
