218 THE ROYAL SOCIETY OF CANADA 



males were somewhat in excess in the sea type, but in the other types 

 the balance was very nearly kept. 



Nearly all the mature coho were in the third year, the exceptions 

 being 2-year males. In the 3-year class, the males and females were 

 almost equal in number. 



The humpbacks were all in their second year, with almost an 

 equal number of males and females. The Rivers inlet fish averaged 

 2 inches longer than the Comox fish. 



The majority of the dogs were 4-year fish, the majority of the 

 remainder 3-year fish, a few 5-year fish and one 2-year. In the Quali- 

 cum dogs there was a larger percentage of 4-year-olds than in the 

 Nanaimo fish. The males were largely in excess in every year, with 

 exception of the 3-year class from Nanaimo. In consequence the total 

 excess of males was large. 



In all types of all species the average length of the male slightly 

 exceeded that of the female, although in the coho the difference almost 

 disappeared. 



The difference in growth rate of the Rivers inlet and the Fraser 

 river sockeye and the Rivers inlet and Comox humpbacks confirms 

 the statement that each species in each river system is a problem of 

 itself. 



In previous papers the problem of feeding young salmon in rear- 

 ing ponds has been discussed. The detailed examination of so many 

 salmon of each species gives further data for the consideration of this 

 matter. It must be remembered that the feeding of young fish in a 

 rearing pond for a year or more does not produce larger fish than 

 those that have lived the same length of time in fresh water. The only 

 advantage of such retention comes from the protection they receive 

 from enemies during the time they are retained. 



In the case of the sockeye, where the great majority remain 

 normally for at least a year in fresh water, and that of the coho, where 

 practically all of them do, such a protection seems desirable. With 

 the humpback and dog salmon, it is entirely different, as these get to 

 the salt water early in the first year and it is not a normal condition 

 to keep them in fresh water. Furthermore, since they grow so rapidly 

 in the sea in the first year, the growth would be much retarded if they 

 were kept in fresh water. Since two-thirds of the spring salmon go 

 down to the sea in the first year and since these that do go down as 

 fry are practically a year ahead of those of the same age that remain 

 in the fresh water for a year or more, the rearing of spring salmon 

 until the second year is of very doubtful benefit. 



