60 THE LIFE OF THE SALMON 
kelts are returning to the sea, we have clean, well- 
fed fish with quite undeveloped reproductive organs 
entering and ascending our rivers, is sufficient to 
show that there are, at all events, a number of 
salmon each year which disregard the reproduction 
of their species. Such fish have sometimes been 
described as barren, but this is simply because at 
the time of capture they show no very evident sign 
of sex or of the active function of their genitalia. 
This missing of a spawning season has led other 
observers to suppose that the salmon is a biennial 
breeder.* The Scottish and Irish salmon marking 
results show that the salmon is both an annual and 
a biennial spawner, and from the study of the scales 
there seems evidence for the belief that some fish 
may spawn less frequently than even every other 
year. 
The salmon lives and grows in the sea, but has to 
enter fresh water to spawn. It frequently enters 
fresh water long before the spawning season. Fish 
doing so in spring are fish which have spent what is 
called the long period in the sea; they have missed 
a spawning season. Summer fish may also be fish of 
long absence from fresh water, but very many of 
them may be regarded as annual spawners, or at any 
rate as fish which are reproducing their species on 
two consecutive years. The understanding of this 
feature—this divided migration—in the life of the 
salmon is in great measure the key to “salmon pro- 
blems.” Both this spawning habit and its results, 
* Atkins, “The Biennial Spawning of the Salmon.” Trans. 
Amer, Fisheries Soc., 1885. 
