FISHERY BULLETIN: VOL. 70, NO. 1 



the scales of fish from Bristol Bay. Usually a 

 few more circuli are found than on Bristol Bay 

 or Asian scales. 



Bristol Bay scales of this age (Egegik River 

 shown) look like Bristol Bay scales of age 2. with 

 an additional freshwater winter mark. The 

 freshwater zone is moderately large and distinct; 

 the circuli are well marked. Circuli of the first 

 ocean zone are also distinct and are fewer in 

 number than on scales from fish of other North 

 American areas except Adak Island. The circuli 

 are usually widely separated near the freshwater 

 zone. These scales, like those from fish of the 

 other Bristol Bay age groups, are usually easy 

 to interpret. 



Fish of this age are rarely found in other 

 North American areas. Scales from these age 

 3. sockeye salmon resemble those of age 2. from 

 the same area but have an additional winter 

 mark in the freshwater zone. Thus, usually the 

 freshwater zone is large (Nimpkish River 

 shown). In Chignik and southeastern Alaska 

 (Petersburg shown) where small freshwater 

 zones predominate, occasionally a fish with a 

 very small freshwater zone with three distinct 

 winter marks may be found. 



Among fish of this age, the number of circuli 

 in the first ocean zone is similar to that of age 

 1. and 2. fish from the same area; thus the num- 

 ber of circuli in the first ocean zone can indicate 

 the area of origin of the fish. 



AGE 4., ALL AREAS (Plate 17) 



Scales that show this age are rare from Asia 

 to Cook Inlet, Alaska, and are almost never ob- 

 served in areas southeast of Cook Inlet. Insuf- 

 ficient numbers of fish of this age group have 

 been obtained to assemble frequency distribu- 

 tions of the number of circuli on the scales of 

 fish from any area. While it is possible that 

 some of these scales may be younger with acces- 

 sory checks, the spacing and appearance of the 

 markings suggests that most of them are actually 

 age 4. 



It appears from the scales which I have seen 

 that the freshwater and ocean zones are similar 

 to those found on scales of fish of age 2. and 3. 

 from the same geographical areas, with addi- 



tional winter marks in freshwater, and conse- 

 quently somewhat larger freshwater zones. For 

 instance, the scales of fish from Lake Dalnee 

 have an enormous freshwater zone, and rela- 

 tively few circuli in the first ocean zone. The 

 Lake Blizhnee fish of this age, on the other hand, 

 have scales with a small freshwater zone with 

 relatively few circuli in each year's growth and 

 with approximately the same number of circuli 

 in the first ocean zone as would be found in most 

 Asian fish of age 2. or 3. 



Fish of the Aleutian Islands show two diflferent 

 types of scales. One type (similar to Lake Blizh- 

 nee scales) has an extremely small freshwater 

 zone with few circuli in each year's growth. 

 Scales of this type have broken and irregular 

 circuli in both the freshwater and ocean zones, 

 as on the scales of many Asian fish. They aver- 

 age fewer circuli in the first ocean zone than 

 Asian fish, however, and often average fewer 

 circuli than on scales from Bristol Bay fish. The 

 second type, illustrated by a scale from Adak 

 Island, is similar to scales of fish of the same 

 age in Bristol Bay (Egegik River shown). The 

 freshwater zone is moderately large with numer- 

 ous circuli, some of which are irregular or 

 broken. The first ocean zone has circuli like 

 scales of age 2. fish from the same locality. Gen- 

 erally the circuli are well marked and more 

 widely spaced near the freshwater zone. 



Scales from Kodiak Island (illustrated by 

 scales from Karluk River and Frazer Lake) have 

 freshwater zones that vary from large to ex- 

 tremely large, 



DETERMINATION OF ORIGIN OF 



SOCKEYE SALMON TAKEN IN 



OFFSHORE WATERS 



This section is not a formal key for classifying 

 sockeye salmon by stock or geographic origin. 

 The purpose of this section is to show how age 

 and scale characteristics illustrated in the pre- 

 vious section of the paper can be used by ex- 

 perienced workers to assist in identifying the 

 most probable area of origin of many sockeye 

 salmon taken in offshore waters. 



Scales of fish from different offshore areas re- 



178 



