FISHERY BULLETIN: VOL. 71, NO. 4 



200 

 150 

 100 

 50 - 





 5 





 15 

 10 



5 







5 







5 







5 







(N=26) 



(N=72) 



(N= 12) 



( N = 2 ) 



_1_ 



I 



30 40 50 60 70 

 TOTAL FISH LENGTH (MM) 



80 



Figure 2. — Length-frequency distribution of sticklebacks 

 (top graph) and length frequencies of age-groups to IV 

 based on otolith readings (lower graphs) of fish collected 

 in June 1967. N equals number of fish. 



20 



30 



40 50 60 



TOTAL FISH LENGTH (MM) 



70 



80 



Figure 3. — Length-frequency distribution of sticklebacks 

 (top graph) and length frequencies of age-groups to III 

 based on otolith readings (lower graphs) of fish collected 

 in August 1967. N equals number offish. 



Table 1. — Average calculated total lengths in millimeters 

 of female ninespine sticklebacks from stations 2 and 3 in 

 the Apostle Islands. 



Station cl 



Year 

 class 



Number 



of 



fish 



Years of life 



81.00 



79.00 



Average empirical length 

 of fish in spring prior 

 to annulus formation 



80.00 



47.08 62.32 71.16 77.53 81.00 



' Total number of fish. 



- Grand average calculated length. 



Table 2. — Average calculated total lengths in millimeters 

 of male ninespine sticklebacks from stations 2 and 3 in 

 the Apostle Islands. 



Number 



Years of life 



Total number of fish. 

 2 Grand average calculated length. 



mation agreed closely with grand average 

 back-calculated length of each assigned 

 age-group (Tables 1 and 2). Empirical 

 lengths slightly exceeded calculated 

 lengths, indicating seasonal growth may 

 already have begun. 



1042 



