202 
THE BOOK OF FISHES 
Photograph by Shirley C. Hulse 
A FIELD HATCHERY OF THE STATE OF OREGON 
Here the eggs are put in troughs of running water, in which they hatch after a greater or less period, 
according to the temperature of the water. The eggs are picked over every day and all sterile or objection¬ 
able ones are thrown out. It is necessary to screen the troughs at this place on account of birds, which 
enter boldly and steal the eggs. The water ousel is the worst of these thieves. 
has its major effect four years later in 
the same region—that is, the normal life 
of this species, from its birth as an egg 
to its death as a parent, is four years. 
The Humpback, on the other hand, is a 
biennial species, a heavy run, with a cor¬ 
responding egg crop, having its effect 
two years later. Dr. Charles H. Gilbert, 
who has made prolonged studies of the 
Pacific salmon in the interests of the 
government, announces, as a practically 
accurate statement of fact, that the 
Humpback dies on its second birthday. 
THE salmon’s “instinct OF NATIVITY” 
AND THE PARENT-STREAM THEORY 
In view of the excellent quality of the 
Humpback and its growing importance as 
a fresh and preserved fish, the govern¬ 
ment now proposes to make a determined 
effort to establish in Puget Sound a large 
run during the off years. This experi¬ 
ment will extend over several seasons, 
and will involve the transfer from Alaska 
of perhaps a hundred million Humpback 
eggs for hatching on Puget Sound. If 
successful it will prove tremendously im¬ 
portant commercially, and incidentally 
the efficacy of artificial propagation will 
be submitted to a crucial test. 
One of the most deeply seated and 
widely entertained theories regarding the 
salmons (and other species of similar 
habits) is that by virtue of a mysterious 
faculty, which has been called the instinct 
of nativity, these fishes return to spawn 
in the same stream in which they were 
hatched. 
The advocates of this view find sup¬ 
port for it in some well-known facts in 
the life of the salmons, such as the oc¬ 
currence of distinctive runs in particular 
streams, the return of marked fish,, re¬ 
sponse to plants of large numbers of 
young, etc. Without entering into a dis¬ 
cussion of this question, it may be said 
that in so far as the theory is borne out 
by facts, the latter may be explained 
without the necessity of investing the sal¬ 
mon and other anadromous fishes with a 
higher order of intelligence than is pos¬ 
sessed by any other creatures. 
