Table 4. — Peak periods of migration of 1- and 2-annulus sookeye salmon smolts from Little Kitoi, 



Phith, and Midarm Lakes, 1955-63 



early migration 41,000 of the 50,000 1-check 

 migrants were stunted fish that averaged 

 about 39 mm. fork length. The later group of 

 1-check migrants had an average length of 

 61 mm. The cause of this atypical condition 

 (small size of smolts and earlier migration) 

 is not known. The peak of the migration of 

 2-check smolts in 1956 was also considerably 

 later than average. Smoker (1957), who re- 

 ported this unusual migration, called attention 

 to the severe winter of 1955-56 and noted that 

 the ice cover was three times as thick as in 

 the previous 2 winters and that the lake had 

 been covered with both ice and snow more than 

 7 mo. 



Survival 



Exact comparisons of estimates of survival 

 among the three study lakes are not possible 

 because the available estimates are based on 

 the egg-to-smolt stage for Little Kitoi Lake 

 and on the fry-to-smolt stage for Ruth and 

 Midarm Lakes. 1 can, however, make rough 

 comparisons by assuming an arbitrary rate 

 of survival fronn the egg-to-fry stage for 

 Little Kitoi Lake and calculating a fry-to- 

 smolt survival from the result. In this section 

 I discuss my estimates of survival in the 

 egg-to-smolt stage in Little Kitoi Lake and 

 the fry-to-smolt stage in Ruth and Midarm 

 Lakes with similar estimates from the litera- 

 ture; I present also my calculations of the 

 fry-to-smolt survival in Little Kitoi Lake 

 when an arbitrary figure is assumed for the 

 egg-to-fry survival. 



Fry-to-smolt stage, Midarm and Ruth 

 Lakes . --Survival to the smolt stage of fry 

 from the 1955 brood year of Little Kitoi Lake, 

 released in Midarm Lake in 1956 (table 2), 

 was 3.6 percent (table 5)--lower than the 

 survival for Ruth Lake in any year of the 



study. In Cultus Lake, Foerster (1938a, 1938b) 

 found the average survival to the smolt stage 

 of introduced fry to be 3.24 percent. He 

 attributed the high mortality to predation. 

 Foerster and Ricker (1941) reported a survival 

 of introduced fry of 13.05 percent after partial 

 removal of predator fishes by gill netting, as 

 compared with an average survival of 4.16 

 percent before gill netting. In Port John Lake, 

 British Columbia, for the 1955 fry that mi- 

 grated in 1956 and 1957, an estimated fry-to- 

 smolt survival of 80 percent is reported, 

 indicating a low level of predation (Fisheries 

 Research Board of Canada, 1958). Survival to 

 the smolt stage of fry introduced into Ruth 

 Lake ranged from 7.3 to 46.9 percent (table 5, 

 fig. 5). The removal of the resident fish 

 populations probably accounted for these higher 

 figures. Because there is only 1 yr.'s estimate 

 for Midarm Lake, it is not considered further 

 in this discussion. 



Egg-to-smolt stage. Little Kitoi Lake .-- 

 Survival rates for potential egg deposition to 

 the smolt stage in Little Kitoi Lake ranged 

 from 2.0 to 8.5 percent (table 5) and are 

 comparable to figures obtained during certain 

 other investigations. For instance. Holmes 

 (1934) estimated a survival of 1 percent from 

 egg to smolt in Karluk Lake. In three separate 

 studies in Cultus Lake, Foerster estimated 

 egg-to-smolt survivals of 1.13 percent (1934), 

 2.5 percent (1936), and 1.80 percent (1938a). 

 Brett and McConnell (1950) estimated an egg- 

 to-smolt survival of 0.4 to 1.1 percent for 

 sockeye in Lakelse Lake. Over a 7-yr. period 

 in the Lakelse Lake system, the average sur- 

 vival from egg to smolt was 1.4 percent 

 (Fisheries Research Board of Canada, 1956). 

 Over a 6-yr. period in the Babine Lake system 

 of the Skeena River area, British Columbia, 

 the survival from egg to snnolt was 0.49 to 

 2.49 percent (Fisheries Research Board of 



