F. to 6U degrees F. (all recordincs made between 10:00 and 12:00 P.M.)o 

 Tlie indi'v-iduals composing this peak concentration obviously required 

 some time to malce the journey upstream (and through Ocqueoc Lalce) from 

 the mouth of the river. Since the mean daily water temperatures (in 

 the lovrer river) rose aiid remained above $0 degrees F. on Hay 16 

 (Appendix C), I presume that the peak migration into the river began 

 on that date and continued until about June 10. 



The last spai^vning migrants observed in the entire river were 

 a pair of sea lampreys which, on July 19 and 20, built a nest and 

 spasmed in the lower river about 3^0 feet below the outlet of Ocqueoc 

 Lalie. It was impossible to ascertain ifnetlisr these spaivners had 

 come up the river from Haiimond Bay or had dropped dovm from Ocqueoc 

 Lalce wiiere they may have been unsuccessful in locating the inlet 

 of the Ocqueoc Fiiver. No spasming sea lampreys could be found in 

 the upper river during the second week in July, Since individuals 

 could still be taken in Ocqueoc Lake by means of gill nets as late 

 as July 15 (Appendix C). I consider the lake as the most probable 

 source. Netting operations undertal<:en in the lalce on August 1 and 

 August 31 to September 1 did not yield any additional sea lampreys. 



Ocqueoc Fiiver , 19U9 : — The earliest migrants to enter the 

 Ocqueoc weir and traps were 21 sea lampreys taken on the night of 

 April 27-28. These were not the earliest migrants to enter the 

 lower river from Hammond Bay. During the period April 12-1);, sea 

 lampreys were first observed at night in several pools immediately 

 below the weir and at several points in the estuary. In succeeding 

 days, the accumulation of sea lampreys below the weir increased and 

 they were more often in evidence. Conditions were favorable for 

 upstream migration on and after April 11 but no lampreys entered 

 the traps until the date indicated (see subsequent discussion of 

 effect of water temperature upon the runs) (Appendix C). I judge 

 from these facts that the weir structure acted as a temporary' barrier 

 •until a greater urge to move on upstream drove the lampreys to 

 search out the trap entrances to continue their journey. 



The run, once started, rose immediately and abruptly in a 

 seven-day period to its greatest pealc (Figure 18), On the nirjit 

 of May 3-li, 2,U76 lampreys entered the traps between nigjitfall and 

 daylight. The bullc of the migrants {9^-^ percent) entered the traps 

 betTreen April 28 and June 10, a lj;-day period. During this time 

 of greatest activity, the run vras depressed by cold weather between 

 llay 9 and 16 and briefly inhibited by cool nights from Llay 26 to 29 

 (Figure 13). 



During the period of greatest migration, 2U-hour trap catches 

 exceeded 2,000 sea lampreys on two occasions and exceeded 1,700 

 individuals on four occasions. 



The rrm declined sharply after June 10 but remained continuous 

 in character until July 12. Relatively few lampreys were talcen each 

 day during this period. Thereafter the run was discontinuous — 

 scattered migrants being taken sporadically until the last sea lam- 



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