1909.] The Life History of the Pacific Salmon. 33 



become an easy prey to various enemies. Indeed the alevin stage seems 

 to be one of the critical periods of the life of the salmon. 



In time, however, the yolk is absorbed and the young fish, now known 

 as fry, as the spring advances, begin their migration to the sea. Not all, 

 however, for apparently a considerable number remain until the following 

 spring in the waters where they were spawned. At least this is the con- 

 clusion to be drawn from the observations of Commissioner Babcock.* 

 In 1903 the Fraser River district and in 1904 in Wannach River which 

 empties into Rivers Inlet, he observed the migration in the spring of great 

 numbers of young fish, the migrants consisting of two sizes, those of the 

 one size averaging in the Wannach River one and one-eighth inches in 

 length, while those of the other size varied from two and a quarter to three 

 inches, some even reaching a length of five or six inches. The smaller 

 fish were the more numerous and may be supposed to be the fry hatched 

 from eggs spawned in the preceding fall, while the larger ones were prob- 

 ably a year older and hence have been called yearlings. 



Starting on their journey in the spring both fry and yearlings descend 

 the river to the sea, at least so we may suppose, although little is known 

 as to their history during the voyage, nor are we more fully informed as 

 to their life while they are in the sea. We may, perhaps, assume that they 

 increase in size very rapidly in the salt water, but where they go when they 

 reach it, whether they remain fairly close to the mouths of the rivers from 

 which they came or whether they wander out into the deeper waters is at 

 present uncertain. Here is a whole chapter in their life history whose 

 pages are almost blank. From the time the young fish start on their 

 seaward journey until they return again to the mouths of the rivers to 

 ascend as an adult fish to the spawning grounds, their history is practic- 

 ally unknown to us. 



We do possess data, however, which give us fairly certain informa- 

 tion as to the time they remain in the sea. One of the facts throwing 

 light upon this question is furnished by the records of the cannery pack 

 of the Fraser River, which shows that the run of every fourth year in that 

 river is greatly in excess of those of the intervening years, so that each 

 fourth year is now recognized by the fishermen and canners as a "big year." 

 How marked are these big runs in each fourth year is well shown in the 

 diagram (Fig. i), which represents the pack of Sockeyes in cases of forty- 

 eight pounds put up by the Canadian canneries for successive years from 

 1893 to 1908 inclusive. In 1893 the pack did not greatly exceed those of 



^Reports of the Fisheries Commissioner for British Columbia for the years 1903 

 and 1904. 

 3 



