550 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



June July Aug Sept 

 First Summer 



June July Aug Sept 

 Second Summer 



June July Aug. Sept 

 Third Summer 



Fioure 10.— Growth of Karluk Lake sticklebacks. Scattered points, modes from length-frequency histograms, 1948 

 and 1949. Curve drawn by inspection. Vertical bars, range of lengths from otolith readings. 



Table 7. — Bare Lake, average standard length of stickle- 

 backs on various dates 



the first summer, depending somewhat on the 

 date of hatching. At the end of the second sum- 

 mer (about 16 months after hatching), the aver- 

 age length is about 42 to 44 mm. At the start 

 of the third summer, the average is about the 

 same, and at the end of August of that summer, 

 the few fish of that age group still alive are from 

 45 to 60 mm. long. The largest individual 



stickleback measured from Bare Lake was 69 mm. 

 standard length (3.3 inches total length). 



In Karluk Lake growth in the early part of 

 the first summer is somewhat less than in Bare 

 Lake because of later hatching. However, the 

 growth thereafter is faster in Karluk Lake, and 

 the maximum size achieved is greater. At the 

 end of the first summer, the average standard 

 length of the Karluk Lake fish is about 32 mm. 

 At the end of the second summer it is about 50 

 mm. At the end of August in the third summer, 

 the average for the fish of that age group still 

 alive is about 60 to 65 mm. The maximum size 

 recorded for Karluk Lake is 78 mm. standard 

 length (3.8 inches total length). 



The growth rate of the Karluk Lake and Bare 

 Lake sticklebacks is greater than that of those 

 in Birket River (Jones and Hynes, 1950), but the 

 latter attain about the same maximum size, since 

 they live 1 year longer. Sticklebacks of various 

 populations from salt and fresh waters in west- 

 ern Europe (Heuts 1947a) ran up to 70 mm. 

 standard length in maximum size. 



Reproduction 



The stickleback in Karluk and Bare Lakes 

 spawns at the age of 1 or 2 years. It is strongly 

 indicated that those fish of either sex which 

 spawn at the age of 2 years die within a few 

 weeks after spawning. In the late .summer many 



