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 simjaly 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 spawn er, 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. 



