THE PRESERVATION OF FISH 205 



fishermen began to troll for salmon, and now trolling 

 is an important branch of the industry. 



While in the sea the salmon grow to be large hand- 

 some fish. When they reach maturity at the age of 

 two to seven years, the age depending upon the spe- 

 cies, they again return to fresh water, usually swim- 

 ming up the same stream from which they came. By 

 this time the roe is fairly well developed, and when 

 the salmon reach shallow water in the upper reaches 

 of the river, which sometimes necessitates a journey 

 of fifteen hundred miles, they spawn. The salmon do 

 not eat after they have entered fresh water, and by 

 the time they reach the head-waters of the rivers 

 they are weak and emaciated. Soon after spawning, 

 they die, having accomplished their life work. 



Each female salmon that is permitted to do so 

 spawns two thousand or more eggs. And yet, so 

 thorough is the fishing, not enough eggs are spawned 

 to maintain the fishery. For this reason, the United 

 States Bureau of Fisheries, the several state fish com- 

 missions, and the Canadian government maintain fish 

 hatcheries in which eggs taken from salmon are fer- 

 tilized and hatched. Later, when they are large 

 enough to take care of themselves, the fry are 

 returned to the stream. Thus the young fish are 

 cared for until they have passed the age at which so 

 many are destroyed by trout and other predatory 

 fishes. 



Salmon canning is a seasonal business. During 

 the autumn and winter, when the salmon are not run- 

 ning, the canneries are deserted save for a watch- 

 man or two. But late in the spring the first of a fleet 



