MATURITY AGE SEX LONGITUDE 



TIME 

 PERIOD 



SAMPLE 

 SIZE 



LENGTH ICM.) 



35 40 45 50 55 60 65 70 75 



Immoture .2 Female 



Maturing 



I75°E.-I80° 5/1-15 9 



I75°W 5/1-15 6 



I66*W.-I62"'W 5/16-31 21 



Mole I7S«E-I80° 5/1-15 10 



I75°W 5/1-15 18 



I66 , W.-I62»W 5/16-31 16 



6/1-15 7 



Female I75°E-I80° 5/1-15 6 



5/16-31 5 



I66'W-I62°W 4/15-31 9 



5/1-15 9 



5/16-31 16 



6/1-15 143 



Male I75*E.-IB0* 5/1-15 II 



5/16-31 9 



I66°W.-I62°W. 4/15-31 7 



5/1-15 7 



5/16-31 14 



6/1-15 154 



Female I75°E.-I60° 5/1-15 7 



I66°W- I62°W. 4/16-31 16 



5/1-15 10 



5/16-31 II 



6/1-15 91 



Male I7S*E- ISO* 5/1 -15 6 



5/16-31 6 



I66°W- I62°W. 4/16-31 14 



5/16-31 5 



6/1-15 78 



Figure 16. — Lengths (end of snout to fork of tail) of sockeye salmon taken in gill nets 

 by Japanese and United States research vessels in April, May, and June 1968. 



most of the samples prevents any detailed dis- 

 cussion of size. The data show, however, that 

 immature sockeye salmon of ocean age .2 were 

 about 35 to 51 cm. long in May and averaged 

 about 44 cm. Maturing sockeye salmon of age 

 .2 were about 41 to 65 cm. long and averaged 

 about 50 to 55 cm. long. Mean lengths for 

 age .3 maturing fish were 56 to 63 cm. Sock- 

 eye salmon taken south of the eastern Aleutian 

 Islands tended to be slightly larger than those 

 taken south of the western Aleutian Islands. 



Chum Salmon 



The age composition of maturing chum 

 salmon, as in sockeye salmon, changed with 

 latitude (table 3). From north to south age 

 .3 fish increased in abundance, and age .4 fish 

 decreased in abundance. Also, the age compo- 

 sition apparently changed from east to west 

 when the total age composition from each 

 cruise track was compared. Age .3 and .4 fish 

 were almost equally represented in catches 

 along long. 166° W. to 164° W., whereas age 

 .3 fish became more abundant westward (55.2 

 percent along long. 175° W. and 74.0 percent 

 along long. 175° E. to 180°). 



The age composition of maturing fish 



changed somewhat from May to June in the 

 area fished by the George B. Kelez: 



The change resulted in a greater proportion 

 of younger ages and the clear dominance of age 

 .3 fish. 



Longline catches by the Wakashio Mara and 

 Hokko Mara also indicated a shift to younger 

 ages from north to south. Longlines took a 

 higher proportion of the older chum salmon 

 than did gill nets. 



Immature chum salmon were most abundant 

 along long. 175° W. The George B. Kelez took 

 only two immature fish in May and none in 

 June along long. 166° W. and 164° W. The 

 small sample taken on the westernmost cruise 

 track indicated that most of the fish were age 

 .2 and .3, whereas on long. 175° W. most were 

 age .1 and .2. 



The mean length of age .1 immature chum 

 salmon, as shown by a small sample, was about 

 26 cm. (fig. 17). Immature age .2 fish had 

 mean lengths of 41 to 42 cm., whereas the 



19 



