The average fork lengths and average 

 body weights of red salmon caught in 1956 

 are shown in figures 5 and 7- 



Chum Salmon 



Analagous to the 3-year-in-oceaxi reds, 

 most of the 5 -year-old chums may be classi- 

 fied as sexually mature fish. The 6-year- 

 old chums returning to spawn in any given 

 year form a small percentage of the run. 

 The i+'year-old chums fall into the same 

 category as the 2-year-in-oce€in reds. 

 Depending on the system and locality, U- 

 year-old chums do return to spawn along 

 with 5-ysar-olds and in instances may be 

 the dominant age group of a run. Some 

 3-year-old chums are sexually mature es- 

 pecially in systems along the more southern 

 area of the North American continent. 



Information on the age composition 

 of chums in systems of the Asian continent 

 is lacking at present. 



Examination of the age composition of 

 chiun salmon caught by the Japanese high- 

 seas fleet in 1955 and 1956 (fig. 2) indi- 

 cates that the h- and 5 -year-old chums 

 dominate the total chum catch. In 1955 

 the fishery caught a predominance of k- 

 year-old chums, but in 1956 5 -year-old 

 chums were dominant. Since the dominant 

 5 -year-old chums of 1956 were of the same 

 brood year as the dominant U -year-old chums 

 of the previous year, we may assiMie that 

 most of the 5 -year-old chums caught were 

 sexually mature fish. However, not all 

 the U-year-old ch'jms can be classified as 

 immature, because, depending on area of 

 origin, many return to spawn in their 

 fourth year. They also cannot all be 

 mature fish; some would have to remain in 

 the ocean for another ye?.r to becone 5- 

 /'esr-cld fish, as in the instance above 

 where nany U-year-old chums of 1955 remained 

 a year in the ocean to be caught as the 

 dominant 5 -year-old chums of 1956. Finally, 

 not all 3-year-old chums caught in the high- 

 seas can be classified as immature fish, 

 although the probability that they are is 

 great. 



The average fork lengths (fig. 3) 

 and average body weights (fig. k) of chums 

 caught in August of 1955 show a decline in 

 both length and weight similar to that of 

 the red salmon. Not even a tentative ex- 

 planation of this condition is warranted 



at present nor of the similar decline of 

 both chums and reds in length and weight 

 during the period from late June to early 

 July. The average fork lengths and weights 

 of chum salmon caught in 1956 by the 

 Japanese salmon fleet are shown in figures 

 6 and 7 • 



Pink Salmon 



All pink salmon in any system or 

 locality return to spawn in their second 

 year, and consequently all pink salmon 

 taken by the fishery are mature fish. 



Figures 3 and k show the average 

 fork lengths and average body weights of 

 pink salmon caught by the Japanese in 

 1955- These figures show the general 

 decrease in both length and weight of pinks 

 from May to mid- June, and the general 

 increase from late June to August. This 

 decrease and increase in average fork 

 lengths and average body weights indicates 

 that this fishery is exploiting different 

 populations of mature fish in its fishing 

 movement from the eastern to the western 

 North Pacific. 



The mean body weights of pink salmon 

 caught by the Japanese in 1956 are shown 

 in figure 7. 



CONCLUSIONS 



The majority of 3-year-in-ocean reds 

 caught by the Japanese high-seas fishery 

 in siny year are sexually mature fish. Tr.e 

 2-year- in -ocean red salmon include both 

 immature and matui^ fish and the proportion 

 of each cannot be assigned at this time. 

 However, more than 75 percent of the 1957 

 catch of red salmon were mature fish. 



As the 5 -year-old chum is comparable 

 in maturity to the 3-year-in-ocean red, 

 and the U-year-old chum to the 2-year-in- 

 ocean red, findings cited above also apply 

 to the chum salmon. The data on hand do 

 not permit ascertaining the proportion of 

 4-year-old chums attaining sexual maturity 

 in the year of capture . 



In 1955 the majority of the chum 

 salmon were 4-year-in-ocean type and 

 probably contained a significant number 

 of immature fish. In 1956 the majority 

 of the chum salmon were 5-year-in-ocean 

 type and mostly mature. 



