TJhat factor or factors (genetic or en-'/irorunental?) are oper- 

 ating against the females or in favor of the raales is in no way 

 apparent. Whether the trend vdll continue is -uncertain, but should 

 it do so it could hardly avoid having sone effect on the sea lamprey 

 population concerned. 



The picturesque characteristics of sparming runs ascribed to 

 this species vAierein the males predominate among early migrants and 

 females among the late ones (mth more or less even division at the 

 pealc of the run) (Surface, 1399) are barely suggested in the runs 

 studied (Appendix C, Tables 3, 6, 9, 13). I^or instance, cui:iulative 

 5-day totals of migrants entering the Carp Creek weir in 19U7 

 display a 1,5 s 1 ratio between males and females quite generally 

 throughout the entire season. The only suggestion of the aforemen- 

 tioned phenomenon occvirred between IJay 1 and 10 i*ien the ratio of 

 raa,les to females v/as about 2:1. At the termination of the run, 

 between July 1 and 13, the males suddenly began, to outnumber the 

 females by a ratio of aLaost 3 • !• 



In 19U95 in both streams studied, a 2 to 2.5 : 1 ratio between 

 males and females prevailed throughout most of the run. After June 

 15 in the Ocqueoc River, the numbers of the sexes became more nearly 

 eque.l but males continued to predominate at all times. 



I presume that the failure of the females to predominate at 

 the end of the run, as they reportedly do in this species (Surface, 

 1399 )i is an expression of the unbalanced sex ratio which is here 

 extant . 



(2) Length composition of spatvn.ing runs 



The extreme range in size of 10,lill migrant sea lampreys, sexes 

 combined, that were examined for length during these investigations 

 was 11.0 to 23.5 inches (279 to 597 mm.). The average length, sexes 

 separately or combined, varied slightly from year to year but was 

 generally vexy oloss to a mean of 17.0 in3he3. There is no gross 

 sexuial dimorphism in lengrth (Table 2 and Figure 19). 



The largest specimens of both sexes were talcen at the beginning 

 of the run and for both males and females the mean total length 

 gradually decreased almost regularly during the course of the run. 

 This ivas more pronoijnced among the females than among the males 

 (Appendlj'r. C, Tables 3, 6, 9, 13). For example, periodic averages of 

 t}.ie total lengt-h of females taken d-^-ing the first half of the Carp 

 Creek run in 19U7 ranged from 17 .U to 18.3 inches. Thereafter, these 

 means' declined to a loiv of 16. U inches tows.rd the end of the rion. 

 Comparable averages of total length among the males ivere generally 

 more consistent. The dominant Deriodic average of total lengths of 



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