CRONE and BOND: LIFE HISTORY OF COHO SALMON 



Figure 2.-Southeastem Alaska and Little Port Walter region, 

 site of coho salmon study. 



first 215 m flows through a muskeg meadow and 

 the most upstream 75 m flows through forest. 



The fish fauna of Sashin Creek consists of pink 

 salmon, 0. gorbuscha; coho salmon; chum salmon, 

 0. keta; rainbow trout, Salmo gairdneri; Dolly 

 Varden, Salvelinus malma; and coastrange scul- 

 pin, Cottus aleuticus. A few adult sockeye salmon, 

 0. nerka, occasionally stray into the stream. 



ADULT COHO SALMON STUDIES 



In our studies of adult coho salmon we deter- 

 mined: 1) size of escapement, i.e., the number of 

 coho salmon spawners that returned to Sashin 

 Creek; 2) average redd life of females; 3) distribu- 

 tion and density of spawners in each study section; 

 4) interspecific competition between coho and pink 

 salmon; 5) age structure of spawners; 6) fecundity 

 of females; and 7) egg retention of spent females. 

 In addition, for comparison with data from Sashin 

 Creek, we obtained data on the age and fecundity 

 of adult coho salmon from Nakvassin Creek in Port 

 Herbert, a 7-km-long fiord about 5 km north of 

 Little Port Walter (Figure 2). Nakvassin Creek, 

 about 0.4 km long, is the outlet stream from 

 30-hectare Nakvassin Lake. Coho and sockeye 

 salmon, Dolly Varden, rainbow trout, coastrange 

 sculpin, and threespine stickleback, Gasterosteus 

 aculeatus, inhabit the lake. These species plus pink 

 and chum salmon inhabit Nakvassin Creek. 



pools and backwaters, for a total of 16,557 m- 

 (Table 1). 



In 1965-67, part of Funny Creek, a small tribu- 

 tary of Sashin Creek near tidewater, was added to 

 the study area. Funny Creek is about 1.5 m wide on 

 the average and slow flowing; the bottom is mostly 

 mud and detritus but has a few gravel areas that 

 are used by coho salmon for spawning. The Funny 

 Creek study area included 441 m^ of stream from 

 its junction with Sashin Creek upstream 290 m; the 



Size of Escapement 



Adult coho salmon generally enter Sashin Creek 

 from early August to early November, but the 

 greatest numbers enter from late August to 

 mid-October. Spawning. usually begins early in 

 October and ends in mid-November. 



Adult salmon have been counted in Sashin Creek 

 since 1934 through a weir at the head of tidewater. 

 From 1934 to 1969, counts of coho salmon at the 



Table 1.- Surf ace area, average gradient, and size composition of bottom materials less than 15.2 cm in diameter in 



three study areas of Sashin Creek. ^ 



'Table adapted from McNeil (1966). 

 2This area includes pools and backwaters. 



899 



