Fisher and Pearcy Distribution and residence of juvenile Chinook salmon 



55 



IS 12 



ANADROMOUS. INC. 

 SPRING CHINOOK 



A 



FALL CHINOOK 



»'l- 



5PRING CHINOOK 



B 



STA. 5 



STA. 4 



,^•4 ^. 



STA. 3 



\'* » x ^ » *-» *^ ;» « « »-» 



STA. 2 





'R I MAY I JUNeH^ JULy| 



jl-U.^ 



STA. 1 



-#-•,-•=*= 



JUNE JULY AUG SEP OCT 



Figure 3 



(A) Numbers of spring chiiiook salmon released in 1987 

 into Coos Bay, Oregon, by Anadromous, Inc. (B) Mean 

 catch per set of fall and sjiring chinook salmon by sta- 

 tion. Dotted lines indicate release dates. 



salmon peaked 10 days, 1-9 days and 1-4 days follow- 

 ing the 19 June, 4 August, and 31 August-3 September 

 releases, respectively, and generally fell to low levels 

 in the inter-release periods. Little increase in catch per 

 set followed the 29 September and 1 October releases. 

 In general, the distribution in the bay of marked fall 

 and spring chinook salmon was consistent with the 

 distribution of unmarked fish. Mean catch per set of 

 fin-clipped fall chinook salmon was much greater at 

 lower bay stations 1 and 1 A than at any other stations 

 (Table 2). On average, all fin-clipped fish were caught 

 at station 1 about 13 days later than at upbay stations 

 4 and 5 (Table 2), suggesting a gradual movement of 

 fish downbay. However, among individual mark groups 

 the trend for later capture in the lower bay than in the 



upper bay was clear only for right-pelvic clipped fish. 

 Most (4 of 6) CWT fish from the 19 June release of 

 spring chinook salmon were caught upbay at station 

 5, and none were caught downbay at stations 1 or 2. 

 In contrast, after the 4 August release, one CWT fish 

 was found at each of stations 1, 2, and 3, and, after 

 the 31 August release, 15 of 16 CWT fish were recov- 

 ered downbay at station 1. 



Juvenile spring chinook salmon were found in large 

 aggregations (67% of the total catch occurred in 5% 

 of the sets) while STEP and wild fall chinook salmon 

 were more evenly dispersed. Spring chinook salmon 

 were present in only 60% of sets after the first release, 

 whereas fall chinook salmon occurred in 95% of sets 

 between 9 May and 30 July. 



