122 THE LIFE OF THE SALMON 



That salmon do not invariably enter fresh water 

 in an excessively over-nourished state I have already 

 noted. A season occurs now and again during which 

 fish in comparatively poor condition leave the sea 

 for our rivers. This in all probability means that 

 the nature of the food taken in the sea has been 

 poor in quality, or, less probably, scarce. Further, 

 the common occurrence of so-called bull-trout enter- 

 ing our rivers from the sea, pale in flesh, often of 

 great size, and having both the gill maggots common 

 to the kelt and the sea lice of the fresh run fish 

 upon them, suggests the belief that amongst fish 

 which adopt the short migration there are those 

 which do not adopt the generous feeding habits of 

 the silvery well-conditioned migrant. 



Such considerations as these seem to me to prompt 

 a certain reserve in accepting the conclusions of Dr. 

 Noel Paton that it is the state of nutrition alone 

 which is the factor determining migration towards 

 the river. We have dwelt at considerable length, 

 in the chapter on the results of salmon marking, on 

 the habit of long and of short periods of sojourn in the 

 sea. Since a salmon in any year can clearly become 

 fully nourished during the time of a short sojourn in 

 the sea, why should it stay an extra year in salt 

 water ? The state of its nutrition does not supply 

 a sufficient reason. The corollary to the view 

 advanced by Dr. Noel Paton is expressed by him 

 thus : " When the salmon has accumulated the 

 necessary supply of material it tends to return to its 

 original habitat." That the salmon is a native of 

 fresh water, in the sense of being born there, I of 



