Table 4. — Comparison of estimates of survival 

 of pixik salmon fry in Sashln Creek before 

 the fry emerge ( hydraulic sampler) and at 

 the time they migrate ( weir) , 1959-63 

 ( from McNeil, 1968) 



•'■ Survival was not estimated in 1960. 



SURVIVAL OF EGGS AND ALEVINS 



Total fresh-water survival of the eggs and 

 the developing young of pink salmon in Sashin 

 Creek has been estimated since 1940 (Olson 

 and McNeil, 1967). These estimates of survival 

 are calculated from the number of eggs car- 

 ried into the stream by the adult females (po- 

 tential egg deposition) and the number of fry 

 migrating to the estuary. A weir had been used 

 to collect the fry that we counted; but because 

 it was severely damaged by ice in winter 1965, 

 we estimated the number of alevins in spawn- 

 ing beds just before the fry emerged. In pre- 

 vious years, estimates of the number of sur- 

 vivors in late March or early April shortly 

 before fry emerged from the gravel were simi- 

 lar to estimates made at the weir in late May 

 or early June when fry migrated to the estuary 

 (McNeil, 1968--see table 4). 



Potential egg deposition in 1964 was calcu- 

 lated to be 2,230,000. This figure was obtained 

 by multiplying the number of females in Sashin 

 Creek (1,305) by the average fecundity of 

 25 females that died en route from Bear Har- 

 bor (1,709 eggs). 



The number of live pink salmon eggs and 

 alevins in spawning beds is determined by 

 sampling randomly selected points with a hy- 

 draulic sampler (McNeil, 1964). Total popu- 

 lation of the 1964 brood year in early April 

 1965, calculated from sample counts, was 

 310,000 live alevins. The 90-percent confidence 

 interval estimate of the total, calculated from 

 log-transformed counts (McNeil, 1964), was 



180,000</i<390,000 



Survival of the 1964 brood year in fresh 

 water was determined for two time periods by 

 estimating the number of live eggs or embryos 

 at three stages in the pink salmon's life his- 



tory: (1) before spawning (potential egg depo- 

 sition); (2) at the end of spawning (actual num- 

 ber of live eggs in the gravel); and (3) at the 

 beginning of fry emergence (number of fry 

 produced). Figure 2 illustrates the fresh-water 

 survival from potential egg deposition to fry 

 for pink salmon of the 1964 brood year in 

 Sashin Creek. 



We sampled 261 random points in Sashin 

 Creek in late September. These samples 

 yielded 2,360 eggs; the lowest density was in 

 section I and the highest in section IV (table 5), 

 as was anticipated from the distribution of 

 spawners (table 3). Ninety-eight percent of 

 the eggs collected contained visible embryos, 

 which indicated that the relatively low per- 

 centage of males in the population of spawners 

 (42 percent) did not cause a high percentage of 

 unfertilized eggs. Usually the numbers of male 

 and female pink salmon spawners in Sashin 

 Creek are nearly equal. 



The number of live embryos in the stream 

 at the end of spawning was estimated from the 

 sample counts (untransformed) to be 55 per- 

 cent of potential egg deposition. Examination of 

 40 spawned females gave the 90-percent con- 

 fidence interval estimate of the number of eggs 

 retained per female as 5< M < 17, or on the 

 average less than 1 percent of potential egg 

 deposition. Thus, an estimated 44 percent of 

 potential egg deposition disappeared during 

 spawning. 



An estimated 25 percent of the live embryos 

 in the spawning beds in late September sur- 

 vived to early April. The lowest density at 

 the beginning of fry emergence was in section I 

 and the highest in section IV (table 5). Hence, 

 the relatively high density of live embryos and 

 alevins in the downstream section did not 

 change appreciably from spawning to just 

 before fry emergence. 



The total fresh-water survival (through 

 early April) was estimated to be 



310,000 (live alevins) 



2,230,000 (potential egg deposition) 



X 100 = 



13.9 percent. 



The 90-percent confidence interval was 8.1 

 percent < /i<17.5 percent. 



The 13.9-percent fresh-water survival of 

 the 1964 brood was more than twice the 6.3 

 percent average of 22 previous broods (table 6). 

 Before 1964, fresh- water survival of the even- 

 year line was less than average. In contrast, 

 the fresh-water survival of the odd-year line 

 has been greater than average since 1951. 



Fry have been scarce from the even-year 

 line for almost 2 decades (table 6), in part 

 because of attempts to annihilate this line. The 

 relatively high fresh-water survival of spawn 

 from the advdts introduced in 1964 produced 

 the largest number of fry from the even-year 

 line since 1942. 



