Photo by Shirley C. liulsc 
SALMON ENTERING THE FOOT OE THE ElSH LADDER 
This is used as a trap, and as fast as the fish are "ripe" they are taken out and spawned 
artificially (see pages 502-509) 
THE SALMONS INSTINCT OE NATIVITY 
AND THE PARENT-STREAM TtlEORY 
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. VVithout entering into a dis- 
cussion of this c[uestion, 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. 
It is true as a general proposition that 
the fish hatched in a particular stream 
return to that stream to spawn, but this 
is largely because that is the most natural 
and most accessible place to go, and it is 
more remarkable when they go else- 
where, as they frequently do. 
The schools of salmon when sojourn- 
ing in the ocean, preparing for their all- 
important function, do not roam many 
miles distant from the mouth of the par- 
ticular stream in which they were born 
and spent the early months of their life. 
Having reached the proper age, they are 
impelled by the spawning instinct to 
move shoreward, and they eventually 
come within the influence of the fresh 
water discharged into ocean, gulf, or bay- 
by a stream that is more likely to have 
been the "parent stream" than another.. 
It thus happens that streams pouring a 
vast volume of fresh water into the 
sea, like the Columbia and Fraser, and 
streams whose mouths are more or less 
remote from others, like the Sacramento, 
are likely to induce the return of a large 
501 
