WAHLE, VREELAND, and LANDER: BIOECONOMIC CONTRIBUTION 



90 KILOHCTERt 



14 Coscode 



15 OiBow* 



16 Corson* 



17 Little Wliite Solmon 



18 Willocd 



19 KhcKitol 



20 Leovenworth 



1 Kloskonine 5 Toulle 



2 Groys River 6 Loxer Kolomo 



3 Biq Creek 7 Kolomo Foils 



4 EloKomin 8 Lewis River 



9 Speelyoi 

 10 Eoqle Creek 

 I 1 Sondy 

 12 Wosliougol 

 1 3 Bonneville 



* Did not porticipote in 1966 brood study 



mark (Ad-RM) was used for hatcheries in the 

 Lower River section — Columbia River mouth 

 to Cowlitz River. The adipose-only finclip (Ad) 

 was allotted to hatcheries in the Middle River 

 section — the Cowlitz River to Bonneville Dam. 

 Hatcheries in the Upper River section — Bonne- 

 ville Dam to The Dalles Dam — were issued the 

 adii)ose-left maxillary mark (Ad-LM). Leaven- 

 worth National Fish Hatchery, the only study 

 hatchery in the Uppermost River section — above 

 The Dalles Dam — was assigned the dorsal-adi- 

 pose finclip (D-Ad). 



The same marks were used for the 1966 

 brood with one exception; at Leavenworth 

 National Fish Hatchery, maxillary marks were 

 added to the D-Ad finclip. Juveniles with D-Ad- 

 RM marks were released at the hatchery and 

 those with D-Ad-LM were trucked downstream 

 and released below Bonneville Dam. The pur- 

 pose of the two marks and release sites was to 

 examine differential mortality due to passage 

 through dams; results will be treated in a sub- 

 sequent report. 



Sources of Variation and Error 



To evaluate variations between broods and 

 river sections, two broods (1965-66) of coho 



HCNARTDAH 



Figure 1. — Location and grouping by 

 river section of Columbia River hatch- 

 eries participating in this study. 



salmon were included in the study, and each 

 river section was allotted a specific mark. Mor- 

 tality due to marking, the most important 

 source of error, was evaluated by comparing 

 marked/unmarked ratios in hatchery releases 

 and returns. To evaluate the dilution effect of 

 returning wild fish on the marked/unmarked 

 ratio at study hatcheries, oxytetracycline (TM- 

 50) was added to the diet of both broods of 

 coho salmon reared at Big Creek (Ad-RM 

 mark) and Eagle Creek (Ad finclip) hatcheries. 

 Tetracycline deposits a permanent mark on the 

 bone structure of feeding juvenile salmon and, 

 at spawning, this mark is readily detected on 

 coho vertebrae under ultraviolet light (Weber 

 and Ridgway, 1967). Thus, wild coho were 

 identifiable and were subtracted from the total 

 unmarked returns to Big Creek and Eagle 

 Creek hatcheries. 



Marked fish were held at Klickitat State 

 Salmon Hatchery to evaluate the degree of 

 mark regeneration. Markers at all participating 

 hatcheries were asked to record naturally miss- 

 ing fins and maxillary bones. Catch samplers 

 were alerted to possible regeneration so they 

 could look for malformed fins. 



Rearing techniques at different hatcheries 

 varied within as well as between river sections. 



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