PEARCY ET AL.: JUVENILE CHUM SALMON 



constructed of 3.2 mm mesh with a 1.3 m wide 

 mouth opening and two 2.7 m wings. The net 

 was positioned across 95% of the width of the 

 stream except during periods of high stream 

 flow (Wilson and Pearcy 1985a). Catches were 

 monitored during day and night periods. The net 

 was removed from the stream on a few occasions 

 during daylight hours and ])eriods of high stream 

 flow. The sampling error resulting from remov- 

 ing the net during daylight hours is assumed to 

 be minimal as <l'7c of the total number of chum 

 fry were caught in the fyke net during these 

 hours (Wilson and Pearcy 1985a). Outmigrating 

 juvenile chum salmon were also sampled in Jack- 

 son Creek with a 3.2 mm mesh bag net stretched 

 across this stream two nights per week between 

 19 March and 25 April 1986. Water depth, tem- 

 perature, cloud cover, and flow rates (1986 only) 

 were recorded from both Whiskey Creek and 

 Jackson Creek during sampling periods. Juven- 

 ile chum salmon in the catches were counted and 

 fork lengths (FL) were measured to the nearest 

 1 mm for all fish or for a subsample of 100 fish 

 per sampling period. 



Fin-clipped (ventral and adipose) chum salmon 

 were released from the Whiskey Creek hatchery 

 to estimate residence time and gi'owth of fish 

 entering the bay at different times and different 

 sizes. Data on the releases of marked and un- 

 marked fish are summarized in Table 1. Eggs 

 from adult chum salmon returning to Whiskey 

 Creek were reared at the hatchery and at the 



Oregon Aqua-Foods, Inc. (OAF) hatchery in 

 Springfield, OR. OAF fish were returned to 

 raceways and acclimated at the Whiskey Creek 

 facility for 10-13 days before release into 

 Netarts Bay. These OAF fish were smaller at 

 release than fish reared at Whiskey Creek in 

 1984, but were larger than Whiskey Creek fish 

 in 1986 (Table 1). Differential mortality of fin- 

 clipped vs. undipped fish was not evident for fish 

 held 3-4 days after marking in 1984 and 1985, or 

 for OAF fish marked 10-13 days before release 

 in 1986. 



Two problems affected releases of juvenile 

 chum salmon from the Whiskey Creek facility. 

 Some marked fish escaped from the raceway and 

 were caught in the bay before their planned re- 

 lease on 16 April 1984. The second problem was a 

 bacterial disease that afflicted many fish reared 

 at the Whiskey Creek facility in April 1986. 

 About 4.4% of the fish died during marking oper- 

 ations, and 7.7% of the fish that survived mark- 

 ing died after being held in the raceway for 24 

 hours. Thus the numbers of fish released on 

 28-29 April 1986 are overestimates of the num- 

 bers of healthy fish actually entering the Netarts 

 Bay. The raceway was sterilized with formalin 

 after this release, and no apparent adverse ef- 

 fects were observed on the OAF fish transported 

 to the Whiskey Creek facility in May 1986. 



Netarts Bay was sampled for juvenile chum 

 salmon from mid-March through late June 1984 

 and 1986 and from late February through early 



Table 1 . — Summary of releases of marked and unmarked juvenile cfium salmon from tfie 

 Whiskey Creek hiatchery in 1984, 1985, and 1986. 



555 



