CANADIAN TAGGING EXPERIMENTS WITH SPAWNED SALMON. 



75 



on that point, as pertained to American salmon. In those days 'scale reading' was not 

 even thought of. So it was concluded that if the fish went to sea as smolts at two years 

 and spawned biennially the fish would be four years old when they returned to spawn 

 for the first time. 



Canadian Tagging Experiments with Spawned Salmon. 



Extensive tagging experiments have been conducted for years by the Canadian govern- 

 ment. Rodd (1923) in his report as Superintendent of Fish Culture for the Dominion of 

 Canada gives the result of the tagging operations from 1913 to 1923. Previous to 1923 

 some 6,149 salmon were tagged and liberated after stripping at the hatcheries situated 

 on the Saguenay, Restigouche, York, Miramichi, Margaree and St. John rivers. Of 

 these salmon, 192 or 3.12 per cent were recaptured either as kelt or as clean fish. The data 

 on these fish include: (1) locality of hberation; (2) date of liberation; (3) locahty of 

 recapture; (4) date of recapture; (5) weight when Uberated; (6) weight when recaptured; 

 and (7) sex. After eUminating the incomplete records and the double recaptures these 

 salmon fall into two groups, (1) 55 kelt and (2) 122 clean or mended salmon. Of the clean 

 fish, 30 or 24.6 per cent were recaptured within one year, 88 or 72.1 per cent within two 

 years, one within three years, and three within four years. From this group 87 salmon 

 with complete and consistent records have been selected for our study. 



TABLE 9. 

 Percentile Distribution According to Month of Recapture. 



Length of absence. The clean salmon may be classified according to the interval before 

 recapture as (1) short-period, (2) long-period, and (3) very-long-period fish. The short 

 period, which indicates an absence of less than one year, includes eight males and 12 

 females. These 20 fish were recaptured in from 5^4 to 976 months, the average length 

 of absence being 7.6 months. Whether all these salmon were returning for spawning is 

 unknown. The long period, which indicates an absence of over one year m the ocean, 

 includes 16 males and 46 females. These 63 salmon were definitely returning for spawn- 

 ing purposes. The time of absence ranged from 15 to 22V2 months and averaged 19.7 

 months. The very long period also represents a return for spawning, but the four salmon 

 in tliis group, all females, may have spawned in the interim and may have been on their 



