Return and Behavior of Adults of the 

 First Filial Generation of Transplanted 

 Pink Salmon, and Survival of Their Progeny, 

 Sashin Creek, Baranof Island, Alaska 



By 

 ROBERT J. ELLIS, Fishery Biologist 



Bureau of Commercial Fisheries Biological Laboratory 

 Auke Bay, Alaska 99821 



ABSTRACT 



Escapement of adult pink salmon to Sashin Creek in 1966 was 5,761 fish-- 

 mostly progeny of 1,866 adults transplanted to the stream in 1964. The adults 

 entered Sashin Creek relatively early in the season and within a short period of 

 time. Most of them spawned in the same two study sections of Sashin Creek ("Lower" 

 and "Middle") used by their parents and by earlier native runs of similar size. The 

 two sections had nearly equal densities of females (about 0.27 per square meter) 

 and potential egg deposition (about 570 eggs per square meter) but different effi- 

 ciencies of egg deposition (about 47 percent in the Middle section and 28 percent in 

 the Lower). The low average efficiency for the entire stream (37 percent) was 

 probably due to the high streamflow during the spawning season. The proportion of 

 combined eggs and alevins alive in March was nearly equal in the Middle and Lower 

 sections (63 and 65 percent), but the disappearance from the end of spawning to 

 just before emergence was markedly different- -about 80 percent for the Middle 

 section and 47 percent for the Lower. Total survival from potential egg deposition 

 to preemergent fry was 9 percent in the Middle section and 15 percent in the 

 Lower. 



Estimated number of pink salmon fry produced in Sashin Creek in the spring 

 of 1967 was 750,000, or 12 percent ofthe potential egg deposition of 6,255,000. This 

 is the survival predicted from the historical relation of total fresh-water survival 

 to the date half the spawners entered the stream. 



Several lines of circumstantial evidence indicate that the adult pink salmon 

 that spawned in Sashin Creek in 1966 were mostly progeny of the fish trans- 

 planted to the stream in 1964. 



INTRODUCTION 



The pink salmon, Oncorhynchus gorbuscha, 

 invariably has a 2-year life cycle, so that 

 two genetically distinct stocks or lines exist 

 (commonly referred to as the even-year or 

 odd-year line according to the year the fish 

 spawn). In many streams one line consistently 

 comprises far more fish than the other. The 

 relative abundance of the two lines in a 

 stream may persist for many generations, 

 or it may be reversed abruptly in one or 

 two generations. The reason for the greater 

 abundance of one line or the other or the 

 cause of reversal of the relation is usually 

 not known (Ricker, 1962). 



To determine the causes for variations in 

 abundance of adult pink salmon the Bureau 

 of Commercial Fisheries has studied this 



species in Sashin Creek, Baranof Island, 

 Alaska, (fig. 1) since 1934; the abundance 

 of the fish has changed markedly both be- 

 tween and within lines (table 1). From 1934 

 to 1938 the number of adults returning to 

 Sashin Creek was relatively stable and equal 

 in the two lines. This condition changed 

 abruptly for the progeny of fish that spawned 

 in 1937 and 1938 and has yet to return to the 

 relatively stable and equal condition. The 

 fishing mortality of the Sashin Creek pink 

 salmon is unknown. 



After 1944, the annual return of pink salmon 

 of the even-year line to Sashin Creek was 

 fewer than 1,000 fish and gave no indication 

 that this line was going to return to its 

 former abundance. Therefore, an attempt was 

 made in 1964 to reinforce the even-year line 

 with fish from another stream: the Bureau 



