FISHERY BULLETIN: VOL. 71, NO. 2 



Table 9. — Frequency distribution according to standard 

 length of three age groups of ripe pygmy whitefish taken 

 from Ross Creek in three different years. 



74.5% were sexually mature. All males age II 

 or older were mature. As in the Bull Lake 

 population, the females mature more slowly 

 than the males. The percentage maturity of 

 the females was 27.8 at age I, 90.2% at age II, 

 and 100% for older fish. Younger breeding age 

 in the males and the larger size of mature 

 females characterize the other widely separated 

 populations (Eschmeyer and Bailey, 1955; 

 Heard and Hartman, 1966). 



Female pygmy whitefish obviously spawn in 

 consecutive years. Mature ripe eggs were pres- 

 ent in the abdominal cavity while smaller 

 eggs, 1 mm in diameter, were developing in 

 the ovaries of ages II and III females. 



Sex Ratio 



Superior and Alaska varied widely. In Flathead 

 Lake egg counts of 28 females ranged from 

 156 to 918 and averaged 588. The larger fish 

 tended generally to have the most eggs, but 

 exceptions were frequent (Table 11). Four large 

 spawners from Bull Lake had from 1,027 to 

 1,136 eggs. In Lake Superior egg counts 

 ranged from 93 to 597 and averaged 362 

 (Eschmeyer and Bailey, 1955); those from the 

 Naknek River system ranged from 103 to 1,153 

 (Heard and Hartman, 1966). 



Conversion of our lengths to total lengths in 

 inches and comparison with Eschmeyer and 

 Bailey's length-fecundity curve shows that pyg- 

 my whitefish from Flathead Lake produce more 

 eggs for their size than do the Lake Superior 

 fish and that those from Bull Lake are even 

 more productive. Fish from Bull Lake with total 

 lengths from 6.0 to 6.5 inches have egg counts 

 slightly more than 1,000 compared with about 

 650 for the Lake Superior fish. If the length- 

 fecundity curve of Heard and Hartman is pro- 

 jected, the Bull Lake population was about the 

 same as fish from South Bay in the Naknek 

 River system, but the Flathead fish produced 

 fewer eggs. Fish in the 5.4- to 5.7-inch range 

 from Flathead Lake had 560 eggs whereas 

 those from South Bay had about 700 eggs. 

 Heard and Hartman explained the differences 

 in fecundity among populations as adaptations 

 to different environmental conditions that pro- 

 duce higher or lower survival opportunities for 

 the species. 



Table 10. — Length and weight of pygmy whitefish from 

 Bull Lake and Flathead Lake. 



The predominance of males in Bull Lake col- 

 lections has been discussed previously. Although 

 variable from sample to sample the sex ratio of 

 all pygmy whitefish taken from Flathead Lake 

 in 1969 was nearly equal (Table 10). When 

 collections for 1967 through 1971 were com- 

 bined, however, males exceeded females by a ratio 

 of 2:1 (Table 5). The sexes were about equal at 

 age II but many more males were taken at age I. 



Fecundity 



The fecundity of individual fish from Lake 



[Ranges in parentheses.] 



594 



