INTRODUCTION 



This report is an outline of the 

 age composition, lengths, and weights of 

 the Japanese high-seas catch and an in- 

 terpretation of these data as they relate 

 to the possible proportion of mature and 

 immature fish contributing to their 

 fishery. 



SOURCE OF DATA 



The age composition data for 1955, 

 1956, and 1957, the fork length data for 

 1955 and 1956, and the body weight data 

 for 1955 were taken from the Interim 

 Reports on Research by the Japanese 

 Fishery Agency for 1955, 1956, and 1957- 



Age data for 195^ were obtained from 

 information gathered by a U. S. Fish and 

 Wildlife Service biologist aboard one of 

 the Japanese motherships. 



Body weights for 1956 were taken 

 from data compiled from Japanese high- 

 seas samples sent to the Seattle laboratory 

 of the Pacific Salmon Investigations, U.S. 

 Fish and Wildlife Service. 



THE DATA 



Red Salmon 



Records to date indicate that red 

 salmon spend a maximum of 4 years in the 

 ocean before returning to spawn. These 

 U-year-in-ocean reds are absent in many 

 river systems and where they occur, their 

 incidence is less than 1 percent of the 

 total run or catch. As the percentage 

 of these it-year-in-ocean reds returning 

 to spawn is very small, and as the major 

 spawners are 3-ysar-in-ocean reds (and 

 even 2-year-in-oceaji reds in some areas), 

 we must regard all k- and nearly all 3- 

 year-in-ocean reds as mature fish, i.e., 

 fish destined to spawn in the year caught. 



In some systems such as the Fraser 

 River, normally the majority of spawners 

 are red salmon which have spent 2 years 

 in the ocean. The Kvichak River (Bristol 

 Bay) had a dominance of 2-year-in-ocean 

 reds returning to spawn in 1956. 



Data on the age composition of 



maturing reds in the river systems of the 

 Asian continent are not available at the 

 present time. 



Examination of the age composition 

 of red salmon caught by the Japanese high- 

 seas fleet in figure 1 (195^-57) indicates 

 the dominance of 2-year-in-ocean reds in 

 even years and of 3-year-in-ocean reds for 

 odd years. The majority of the 3-year-in- 

 ocean reds caught by the Japanese fleet in 

 both even and odd years were undoubtedly 

 sexually mature fish. 



Not all of the 2-year-in-oceaJi reds 

 caught in the high-seas can be classified 

 as mature fish, because some will probably 

 remain in the ocean for another year to 

 become the 3-ysar-in-oce£in reds. Neither 

 can all these 2-year-in-ocean reds be 

 classified as being immature fish because, 

 as previously stated, in some systems the 

 majority of spawners are fish which have 

 spent only 2 years in the ocean (e.g., 

 Fraser River and Kvichak River, 1956)- 



In table 1 the eige composition of 

 the 1957 red salmon sampled aboard the 

 motherships is expressed in percentages. 

 By applying these percentages to the total 

 red -salmon catch the catch of each age 

 group was calculated. We may assvmie that 

 most of the 3-year-in-ocean reds (15,100,000 

 fish) were mature. Twenty-four percent 

 (i+, 700,000 2-year-in-ocean reds) represents 

 the catch of mixed immature and mature fish 

 in the 1957 high -seas catch. The actual 

 percentage of immature red salmon was 

 probably somewhat less than 2U percent. 



The number of 1-year-in-ocean reds 

 taken by the Japanese in any year is 

 insignificant. 



The average fork lengths (fig. 3) 

 and average body weights (fig. ^) of red 

 salmon sampled aboard 10 Japanese mother- 

 ships in 1955 shows the decline in average 

 length and average body weight during the 

 month of August, even with a greater per- 

 centage of 3-year-ln-ocean reds making up 

 the total catch. The fishing area in 

 August of 1955 is along the eastern coast 

 of Kamchatka, and consequently until com- 

 plete and accurate data can be obtained on 

 the red salmon populations in the river 

 systems of the Asian continent, no expla- 

 nation can be given of the catch of small 

 3-year-in-ocean reds during August. 



