Age group 5^, (1.3). One winter in fresh water, 



three in the ocean. 

 Age group 60 (1.4). One winter in fresh water, 



four in the ocean. 

 Age group 7o (1.5). One winter in fresh water, 



five in the ocean. 



AGE GROUPS WITH TWO GROWING SEASONS IN 

 FRESH WATER (Plate 14) 



These age groups also make up many impor- 

 tant runs of sockeye salmon. The Ozernaia River 

 in Asia, a number of tributaries of Bristol Bay, 

 and Karluk River on Kodiak Island are areas 

 where fish of these age groups predominate in 

 the spawning runs in most years. Fish of a given 

 year class may be in tlie spawning run one year 

 as age group 4-, ("jacks") ; dominate the run the 

 next year as age group 5.^ and (in some areas) 

 the following year as 6:;'s ; and produce an occa- 

 sional 7-, the following year. 



Examples of the following age groups are 

 shown : 



Age group 83 (2.0) . Two winters in fresh water, 



none in the ocean. (This illustration is from 



an immature fish, not an adult.) 

 Age group l.-; (2.1) . Two winters in fresh water, 



one in the ocean. 

 Age gi-oup 5;; (2.2) . Two winters in fresh water, 



two in the ocean. 

 Age group 6;; (2.3) . Two winters in fresh water, 



three in the ocean. 

 Age gi'oup ?:; (2.4) . Two winters in fresh water, 



four in the ocean. 



AGE GROUPS WITH THREE GROWING SEASONS IN 

 FRESH WATER (Plate 15) 



Fish of these age groups are common in the 

 Karluk River, Alaska, and in some Asian areas. 

 In some years they may make up a substantial 

 lx)rtion of the spawning runs in these areas, pri- 

 marily as age groups 64 and Tj. Examples of the 

 following age groups are shown: 



Age group 44 (3.0). Three winters in fresh 

 water, none in the ocean. (This illustration is 

 fi'om an immatui-e fi.sh, not an adult.) 



Age group 5^ (3.1). Three winters in fresh 



water, one in the ocean. 

 Age group 6, (3.2). Three winters in fresh 



water, two in the ocean. 

 Age group 7^ (3.3). Three winters in fresh 



water, three in the ocean. 

 Age group 8, (3.4). Three winters in fresh 



water, four in the ocean. 



AGE GROUPS WITH FOUR GROWING SEASONS IN 

 FRESH WATER (Plate 16) 



In areas where fish with three growing sea- 

 sons in fresh water are common, occasional fish 

 stay in fresh water another year. These fish are 

 rare. Examples of the following ages are shown : 



Age group 6,-, (4.1) . Four winters in fresh water, 



one in the ocean. 

 Age group 7-, (4.2) . Four winters in fresh water, 



two in the ocean. 

 Age group 85 (4.3) . Four winters in fresh water, 



three in the ocean. This group is very rare. 



SCALES WITH IRREGULAR OR 

 DEFORMED FEATURES 



Some scales are of little or no value for age 

 or racial study because they are regenerated 

 (plate 17). Others may be unsuited for these 

 studies because of resorption (plate 18), or for 

 a numl)er of other reasons (shown in plate 19). 



REGENERATED SCALES (Plate 17) 



When a salmon loses a scale, a new one rap- 

 idly replaces it.'- The new scale does not form 

 circuli until it approximates the size of the scale 

 that was lost. Normal scale growth then resumes, 

 and circuli form regularly thereafter. Regener- 

 ated areas range from a small portion of the cen- 

 ter of the scale to almost the complete scale. 

 When a scale is lost from large fish, the resulting 

 regenerated scale is often of atypical size and 

 shape. 



Scales that were regenerated before the fish 

 migrated to the sea can be used to determine the 



'-Unpublished results of my experiments a few years ago showed 

 that lost scales of coho (O. kitiutch) and chinook (O. t^haii-ytsrha) 

 salmon were replaced and had resumed normal growth within 1 

 month, even in fish which were in poor physical condition. 



PHOTOGRAPHIC ATLAS OF SOCKEYE SALMON SCALES 



265 



