Fisher and Pearcy Distribution and residence of juvenile chinook salmon 



53 



Figure 2 



Len^h-lVequency distributions of juvenile chi- 

 nook salmon caught in Coos Bay, Oregon, in 

 beach seines in 1987. Numbers of marked fall 

 chinook salmon released by the Salmon and 

 Trout Enhancement Program (S) and spring 

 chinook .salmon released from Anadromous. Inc. 

 (A) caught in each length category are indicated. 

 An "A" or "S" without a number represents a 

 single fish. Heavy horizontal lines indicate 

 lengths ( ± 2 SD) of production groups of spring 

 chinook salmon released by Anadromous, Inc. 

 Arrows indicate the lengths used to separate fall 

 and spring chinook. 



Results 



Immigration of fall chinool< salmon 



Juvenile wild and STEP fail chinooi< salmon were 

 caught in the bay in large numbers starting in late May 

 (Fig. 2). Only two juvenile chinook salmon were cap- 

 tured during our first two sampling trips on 25-26 

 April (8 sets) and 9 May (6 sets). Catches of juvenile 

 wild and STEP fish in the lower reaches of the Milla- 

 coma and Coos Rivers entering the bay peaked on 

 15 May and 26 May, respectively, and declined to low 



levels after mid- June (R. Bender, Oreg. Dep. Fish 

 Wildl., P.O. Box 5430, Charleston, OR 97420, pers. 

 commun., March 1988). 



Size-frequency distributions 



Distinct modes in the length-frequency distribution of 

 juvenile chinook salmon provided a basis for separating 

 small STEP and wild fall chinook salmon from large 

 Anadromous, Inc. chinook salmon until the end of July 

 (Fig. 2). Recoveries of fin-clipped STEP fall chinook 

 salmon (S in Figure 2) confirmed that the mode of small 



