possibly aaonc other thincs, by a strong positive rhootropic re- 

 sponse and/or a positive tlierniotropic reaction to the higher tem- 

 perature Oi tlie creek's discharge. If either or both of these 

 responses exist, then conditions which deflect the creek's dis- 

 charge into a narrovf, shallov: band in the zone of wave action would 

 materially re'Iuce tlio chances of a sea lajiprey finding that strean 

 as it rr'oves along the lake shoreline. Erratic decliies in migra- 

 tory activity that are not satisfactorily explained by water tem- 

 perature variations occurred on April 26 and 28, I'aj It, 6, 16, 13, 

 and 22, and June 13 and 17, 19h7 (Figure 15). In nost everj^ case 

 these can be associated with periods of easterly, onshore irinds. 



I do not believe that moderate to strong onshore vfinds would 

 have any appreciable effect upon the discharge of larger streams 

 such as the Ocqueoc River. It vrould talce a gale of storm propor- 

 tions to deflect the discharge from such a streaa uiider most con- 

 ditions . 



No correlation exists between stream voluine as reflected by 

 depth gauga readings ai'id the sea lamprey run except insofar as 

 rapidly rising water levels (resulting from cold rains or melting 

 snov;) v;ere generally accompanied by declining water temperatures 

 (Figures 15-13). 



Observations on turbidity and routine 025''gen and carbon di- 

 oxide deterr.iinations of the streasns studied in 19h7 showed no 

 evident relationship of these properties to the run. It vrould seen 

 that the amount of turbidity and the chemical quality of the water 

 as found in the streams studied have little or no relation to the 

 incidence or magnitude of Great Lakes sea lamprey runs. Both clear 

 and turbid v/aters are entered by migrants. Carp Creek and tlie 

 Ocqueoc Iliver are both relatively clear vfhen runs occur. On the 

 other hand, in the Lanlstique Pdver, Schoolcraft County, belov; the 

 paper mill in that stream, sea larnpreys enter channels in the es- 

 tuary which carrj' a vsi"^." heav;;,"" suspension of wood pulp waste, 

 rurtiien^ioi-e, upon reaching the paper m.ill ivhich blocks the river, 

 large numbers of them formerly entered a pipe discharging the 

 combined hot pond and plant sewage imstes and traversed this pipe 

 to reach a small seepage channel above the mill (this latter con- 

 dition can no longer occur due to alterations in the level of 

 the waste pipe outlet). 



(3) Time of migration during the day 



It has been previously observed that the greatest upstream 

 nover.ent of sea lampreys occurs during the hours of dar'cness. For 

 example, among the runs of three years captured in Carp Greek, the 

 proportion of individuals entering the trap during the hours of 

 full daylight varied from O.U to 1.9 percent of the total run in 

 any year. From 93.1 to 99.6 percent m.oved upstream during the 

 hours of darkness. Of those lampreys migrating between 6:00 P. L, 



-hi - 



