MOSHER: SCALE FEATURES OF SOCKEYE SALMON 



circuli) are found on the scales from Ketchikan, 

 Petersburg, Copper River, and Columbia River 

 fish; even fewer circuli (and fewer broken 

 circuli) are found on the Fish Creek and Kodiak 

 Island fish, whereas the least number of circuli 

 (and the most complete and regular circuli) are 

 found on the scales from Aleutian Island and 

 Bristol Bay fish. 



The reasons for some of the fish from these 

 areas having such a large freshwater growth 

 zone is a subject for future research. The nu- 

 merous streams and tributaries of the larger 

 river systems encompass a wide range of en- 

 vironmental conditions. It is likely that these 

 fish are spawned and grow in nursery areas with 

 excellent conditions for freshwater growth. In 

 some years the growth conditions in certain 

 streams may be better than in other streams, 

 contributing to the year to year variation in 

 numbers of fish with this scale type. 



In Rivers Inlet, sockeye salmon with scales 

 showing this age are rare. The scales of the few 

 fish that have been found, however, are of typical 

 Rivers Inlet appearance: a small freshwater 

 zone with only a few (mostly broken) circuli 

 in each year's growth, a fine-textured first ocean 

 zone with numerous circuli, and a second (and 

 subsequent) ocean zone of typical ocean type 

 circuli. Thus the scales show the two large areas 

 of contrasting texture, like those of Rivers Inlet 

 scales of other ages — Plates 1 and 9. (Note how 

 much the scale area to the end of the first ocean 

 zone, white arrow, resembles the freshwater 

 zone of the Columbia River scale on this plate.) 



AGE 3., ASIA (Plate 15; Tables 8a and b) 



Usually fish of this freshwater age are in sub- 

 stantial numbers only in the Asian areas and in 

 Kodiak Island streams, but a few are also found 

 each year in Bristol Bay, especially in the Egegik 

 and Naknek Rivers. 



On the Asian side of the Pacific Ocean, scales 

 from fish of the Ozernaya, Bolshaya, and Kam- 

 chatka Rivers and the Okhotsk Sea do not differ 

 much (column 1 of Table 8 shows data from fish 

 taken off the southeast coast of the Kamchatka 

 Peninsula where a number of Asian stocks inter- 



mingle) . The scales of most Asian fish, except 

 those from Lakes Blizhnee and Dalnee, have 

 relatively small freshwater zones with only a 

 few circuli in each year's growth. Many of the 

 circuli are irregular, broken, and closely spaced. 

 The first ocean zone of these scales is like that 

 of the age 1. and 2. fish from the same geograph- 

 ical areas. There are a few more circuli present 

 on the scales of these fish than on those from 

 Bristol Bay, and the circuli are generally uni- 

 formly spaced. An area of wider spaced circuli 

 may be present in the first ocean zone, but it 

 generally is less pronounced than on scales from 

 Bristol Bay fish. 



Fish of this age are also found in Lake Blizh- 

 nee. The scales have a very small freshwater 

 zone with very few circuli in each year's growth. 

 The first ocean zone of these Lake Blizhnee fish 

 is also like that of the other Asian fish except 

 those from Lake Dalnee. 



Fish of this freshwater age are relatively com- 

 mon in Lake Dalnee. The scales are distinctive: 

 a very large freshwater zone with numerous, 

 usually clear-cut circuli. The freshwater zone 

 makes up a larger portion of the scales of fish 

 from Lake Dalnee than of fish from any other 

 area in Asia or North America. As in age 2. 

 and 4. fish, the first ocean zone often had fewer 

 circuli than usual for Asian fish — sometimes 

 even fewer than on scales from Bristol Bay or 

 Adak Island fish. 



AGE 3., NORTH AMERICA 



(Plate 16; Tables 8a and b) 



As noted above, Kodiak Island has the most 

 sockeye salmon of age 3. on the American side 

 of the Pacific Ocean. In some years a major 

 portion of the run to the Karluk River may be 

 of individuals of this freshwater age with 2 or 

 3 winters in the ocean (the 3.2 and 3.3 ages). 

 In most years substantial numbers of age 3. fish 

 are found. The freshwater zone of the scales 

 of these fish is relatively large; the circuli are 

 well separated and usually well marked, although 

 more of the circuli may be irregular or broken 

 than on most Bristol Bay scales. The first ocean 

 zone is also well marked; the circuli are distinct 

 and often widest near the freshwater zone as in 



177 



