572 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



In the June collections the disc length, snout 

 length, and tail length showed distinct differences 

 between males and females. 



Seasonal changes in the various body sections 

 were somewhat erratic. In general, the relative 

 size of all body sections except tail length tended 

 to increase as the seasons progressed from Septem- 

 ber-October through June. The tail length de- 

 creased during this period. 



Table 12. — Relative length of the tail of Cayuga Lake sea 

 lampreys during 3 collecting periods 



[Expressed as thousandths of the total length] 



Table 13. — Relative body depth, disc length, snout length, 

 and length over gill openings of sea lampreys from Cayuga 

 Lake and Seneca Lake 



[Expressed as thousandths of the total length] 



Morphometric Comparison of Cayuga Lake and Seneca 

 Lake Sea Lampreys 



Sea lampreys from Seneca Lake superficially 

 appeared to be longer and proportionately greater 

 in body girth than specimens from Cayuga Lake. 

 Even though the two lakes are connected by the 

 Seneca River (Barge Canal), because of the loca- 

 tion of the interconnecting river in relation to the 

 deepwater areas of the lake, it was thought that 

 little interchange of sea lampreys takes place be- 

 tween the two. In view of these conditions it was 

 desirable to make a taxonomic comparison of speci- 

 mens from the two lakes. Body proportions and 

 the number of teeth 3 and myomeres were com- 

 pared. 



Body proportions. — Measurements of the follow- 

 ing body sections were taken from collections of 

 sea lampreys captured in both lakes during Sep- 

 tember and October: body depth, disc length, 



I The terms "tooth" and "teeth" are used in the broadest sense of their 

 meaning; the sea lamprey's dental armature, consisting of cornified epithe- 

 lium, does not represent true teeth. 



Table 14. — Relative length of tail of sea lampreys from 

 Cayuga Lake and Seneca Lake 



[Expressed as thousandths of the total length] 



snout length, length over the gill openings, and 

 tail length (tables 13 and 14; fig. 7). Comparison 

 of these data revealed a very close agreement in 

 the relative size of snout length, length over gill 

 openings, and tail length in specimens from the 

 two lakes. Distinct differences between the two 

 samples were disclosed in the relative length of the 

 disc and body depth. 



In the previous section it was shown that disc 

 length decreased proportionately with normal 

 (nonbreeding) growth, and that body depth in- 

 creased proportionately witli normal growth. 

 Since the Seneca Lake specimens were larger and 

 their body proportions were consistent with 

 changes accompanying additional growth — i.e., 

 disc length was smaller and body depth greater — 

 these differences were considered to be of environ- 

 mental rather than genetic origin. 



