As a general in.ile, orOy a very {^mall percentage of developed 

 (inatijre) eggs remain imspaimed^ the estimated average percentage 

 "vms 5.00 percent. Ataong the specimens there are, horrever, several 

 notable exceptions. For tvro individuals, the estimated percentages 

 of unspaT/ned egcs vrere 28.6 and 37-2. Two others vrere identical 

 in having an estimated 19. h percent of their eggs imspaivned. All 

 the females displaying a relatively higli percentage of unspavmed 

 eggs vrare late migrants, appearing at the very end of the spaiming 

 season. Observations made upon late migrants of both sexes indi- 

 cate a very loiv vitality at that time. I suspect that these speci- 

 mens examined which contained a large number of unspavmed eggs 

 vrere unable to complete their spasming act before approaching 

 death made them incapable of doing so. In vie-w of this, the average 

 percentage of 5«00 xonspa^vned eggs is believed to represent the 

 maj:imum average that occui'sj indications are that this average 

 iTOuld be lower if computed for specimens found spent nearer the 

 beginning of the spaTjning season. 



^' Spawning habits and spavming requirements 



of the sea lamprey 



The date upon Tvhich the following discussions are based vrere 

 collected exclusively in the Ocqueoc River watershed bet'vveen April 

 29 and July 3, 19h7, and April 11 and August 10, 19U8, v^en the 

 spavming run of sea lampreys in each year was observed. In 19h7 , 

 the beginning, pealc, and conclusion of spawning activity were 

 observed, and a siirvey ofthe physical characteristics and intensity 

 of spavming in each area of the river was made; spavming behavior^ 

 spavming sites, and nest construction ivere likeivise studied. 



In 19i|8, the onset, peali and cessation of spawning were again 

 observed in detail in selected areas of the river. Regular visits 

 ivere made to these sites so that all degrees of spawning actiirity 

 ■;ould be noted and compared vri. th related environmental conditions. 

 Farther observations on the spavming behavior of the sea lamprey 

 were made in this year. 



Daily records of air and water temperature, vrater level, and 

 Tireather were obtained in both years so that the effect of these 

 factors upon the spavTiing and other activities of the sea lamprey 

 ^ould be determined (described for 19^7 in Section IV and in 

 Appendix C, and for 19l|.3 in Appendix G, Table 3). 



Fnysical characteristics of the Ocqueoc River vratershed 



The geographic location and a generalized description of the 

 Ocqueoc River are given in Section IV. Briefly, this river drains 

 in a northerly direction to Ocqueoc Lal<:e and thence easterly into 

 Hammond Bay of Lake Huron (Figure 28). It reportedly embraces 89 

 miles of ViTatercourse (determined on large scale maps with a 



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