read the projected images to determine age. By a time- 

 consuming process, features on the scales are measured to 

 determine continental origin. The age composition and 

 origin of the catches are then given to the biometricians to 

 prepare their forecasts of sockeye salmon runs. 



To speed the processing of fish scales and open new areas 

 of research, the laboratory obtained a semiautomatic scale- 

 reading machine (fig. 18). The machine, made to our spe- 

 cifications, is the first of its kind. Processing should be 

 accelerated from the present rate of about one scale per 

 hour to about one scale per minute; added benefits would 

 be more information derived from each scale than was pos- 

 sible by human scale readers. The electi-onic scanning and 

 computer capabilities of the machine should give an imme- 

 diate print-out of age and a classification as to the origin 

 of the fish. 



Our biologists are searching for new clues to pinpoint 

 racial distinctions of salmon. They are analyzing scales, 

 bones, blood, muscles, and eye lenses for genetic or biochem- 

 ical peculiarities. The chemical composition of scales and 

 bones may reflect the mineral chemistry of waters where 

 the fish were born. The patterns in which circuli are formed 

 on scales during the ocean growth of salmon show promise 

 as indicators of differences between maturing and nonma- 

 turing fish. Blood sera of sockeye salmon have variable 

 LDH (lactate dehydrogenase isozyme) patterns that are po- 

 tentially useful as genetic "markers" to differentiate stocks 

 (fig. 19). 



FIGURE 19.-Bands in starch gel illustrate different LDH 

 patterns in sera of sockeye salmon. Fish from western Alaska 

 or Kamchatka River in eastern Siberia have one of three dif- 

 ferent patterns (left), and fish from southern British Columbia 

 or Washington State have only one pattern (right). 



— 16 — 



