52 



Fishery Bulletin 88(1). 1990 



I ... V I 



125- 124" 



Figure 1 



Coos Bay, Oregon, showing five stations 

 routinely sampled and two sites occasion- 

 ally sampled (lA and 3 A) for juvenile Chi- 

 nook salmon with a beach seine in 1987. 

 The Anadromous, Inc. release site on North 

 Spit is indicated by an arrow. The Milia- 

 coma River (not shown) is a tributary of the 

 Coos River. Also shown are other estuaries 

 mentioned in the Discussion. 



Generally, we sampled from the lower to the upper bay 

 in the morning and in the opposite direction in the 

 afternoon. Occasionally sets were made at two othei- 

 sites (lA and 3A in Fig. 1). 



The substrate at all stations was sand except at sta- 

 tion 5 where it was gravel and mud. During low tide 

 the seine usually sampled parts of eel grass beds at sta- 

 tions 2, 3, and 4. 



About 415,000 subyearling fall chinook salmon were 

 released in 1987 by the Salmon and Trout Enhance- 

 ment Program (STEP) into tidewater tributaries of the 

 Coos River between 27 and 35 km above station 5 

 (Fig. 1). These subyearling fall chinook salmon were 

 released between 30 April and 28 June (half before and 

 half after 23 May). Average fork length (FL) of fish 

 at release ranged from approximately 48 to 94 mm 

 (converted from mean weights, T. Rumreich and 

 R. Bender, Oreg. Dep. Fish Wiidl., P.O. Box 5430, 

 Charleston, OR 97420, pers. commun., March 1988). 

 Of STEP fail Chinook salmon released in 1987, 74% 

 were supposed to be fin-clipped. However, the actual 



percentage of fish with recognizable marks was not 

 known because marking efficiency was not evaluated. 

 Wild fall chinook salmon caught in the lower Millacoma 

 and Coos Rivers were about the same size as STEP 

 fish. 



Over 5 million subyearling spring chinook salmon 

 were released into Coos Bay in eight groups between 

 19 June and 1 October 1987 from Anadromous, Inc.'s 

 holding and release facility located on North Spit 

 (Fig. 1). These spring chinook salmon were consider- 

 ably larger than the STEP or wild fall chinook salmon 

 and averaged 123-156 mm FL at release. Between 

 and 5.9% (average 3.6'7o) of the fish in each group 

 were coded-wire tagged (CWT) and had clipped adipose 

 fins. We sampled the bay 1-2 days before and after 

 each Anadromous, Inc. release and at about weekly 

 intervals between releases. 



