Although nearly all of the doTmstream migration in both streams 

 studied (Ccqueoc and Carp Lake rivers) occurred after the mean daily- 

 water temperature had fallen beloi? I4.I.O degrees F., there Y^as no 

 evident relationship between changes in water temperature and the 

 amount of migratory activity. 



In the Ocqueoc Pliver in the 19h5-19h9 season, the first dotvn- 

 stream migrant vras taken at the weir on November 1, 19hQ', scattered 

 individuals continued to reach the weir until November 20. On that 

 date and on November 22, rainstorms caused the first appreciable 

 increase in the river flow above the prevailing levels. Coincident 

 rri. th this rise in -water level came the first surge of do-'."mstream 

 movement (Figure 6I and Appendix 1, Table 1). Frequent storms of 

 rain and of rapidly melting snow maintained tbJ.s increased volume 

 of flow until December 8 when colder and more stable weather re- 

 duced the volume. Do-'.vnstream movement vra.s sustained during this 

 period and fluctuated within it as the volume of flovr varied; the 

 acti\T.ty declined abruptly as water levels declined after December 8. 

 Thereafter, during the entire -v/inter and early spring (to llarch 20), 

 the run was minor and erratic. Hovrever, at least a few individuals 

 came downstrear. nearly ever;- day. During the periods, January I6 

 to 2li and February 2? to llarch 1;, brief thaws sjid/or cold rains 

 caused temporar;^ rises in -ivater levels. These were accompanied by 

 small increases in the size of the dovmstream migration. 



On March 22, two days after trapping operations were terminated, 

 the Ocqueoc River began to rise as a result of -the spring thaw and 

 breaJcup and attained its major spring flood levels during the suc- 

 ceeding 22 days (to April I3). Between L'arch 23 and 30, a varying 

 but very large number of young sea lampreys Virerc observed passing 

 do-imstream during -fche daylight hours. These observations were made 

 by a r/ork crew and by mj^self Tjliile repairing the weir structure. 

 'j?he bulk of the downstream migr-ation in this season (19liS-19l;9) un- 

 doubtedly occurred during this 3-day period. Some dovmstream mi- 

 gi-ants Tirere obser^red or v;ere found caught somevj-here on the Vv-eir 

 structure until April 13 . Field observations in the Ocqueoc Fdver 

 itself coupled vd.tl: knowledge of the character of the Carp Lalce 

 River run (subsequently described) suggest that, except for a few 

 scattered migrants, the domstream ralgration ended very shortly 

 .^fter the latter date. 



In -the Carp Lake River in tlie 19h'^"19h9 season, a single fully- 

 tran.sformed sea lamprey came dovmstream into the 'trap on October 7, 

 l^Ii-S; tv/o additional indi^/iduals were talcen on October 21 and 23- 

 S'ostained dovnastream m.ovement began on November 2, reached a sharp 

 pealc on November 21, and subsided with equal rapidity. Some appre-' 

 liable movement continued until December 9 (Figiore 62 and Appendix 

 I., Table 2). Tlie early por-bion of this period was characteri^.ed iij 

 rising vrater levels res-alting from light rains and wet snow. llea.-\ry 

 rains from Novem^bcr 1? to 19 increased the volume of flow; the 

 flcod crested on the night of November 20-21 and on -'chat night a 



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