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Fishery Bulletin 92(4). 1994 



Some of the freeze-branded fish were subsequently 

 recovered downstream at John Day Dam. An airlift 

 pump (Sims et al. 5 ) was used to extract fish from the 

 gatewells at Turbine Unit 3; however, it was unknown 

 what proportion of recovered fish represented those 

 passing into the turbine intake. Reliable estimates 

 of that proportion are not available. Each day, col- 

 lected fish were examined and brands enumerated. 

 To provide a relative measure of daily passage at John 

 Day Dam, the daily catch was expanded in propor- 

 tion to the daily total river flow that was discharged 

 through the sampled turbine unit. That proportion 

 varied with prevailing spill volumes and the num- 

 ber of turbine units that were operating. Some wa- 

 ter was also discharged through the navigation locks 

 and fish ladders, but the amount was small, typi- 

 cally less than 1% of the total river discharge (Sims 

 et al. 6 ). The expanded daily catch was referred to as 

 the passage index and was a relative measure of the 

 number offish passing the entire dam. The calcula- 

 tion of the passage index assumed 1) that the pro- 

 portion offish passing the dam through the spillway 

 was equal to the proportion of water spilled, and 2) 

 that the proportion offish entering the gatewells from 

 the turbine intake was relatively constant. 



For each branded group, we constructed a distri- 

 bution of daily passage indices. The median migra- 

 tion time for each group was estimated as the elapsed 

 time between the known release date at McNary Dam 

 and the date of median passage index distribution 

 at John Day Dam. In addition, we estimated the pas- 

 sage index for the entire population passing John 

 Day Dam each week. 



Additionally, to characterize the movement pat- 

 terns within John Day Reservoir, we freeze-branded, 

 released, and subsequently recaptured zero-age 

 chinook salmon at fixed cross-sectional transects lo- 

 cated along the length of the reservoir (Fig. 1). We 

 sampled fish with a 305 x 11 m purse seine ( 12-mm 

 stretched mesh, knotless web throughout) aboard an 

 11-m power-block seiner. At each transect, a seine 

 set was made as close to each shore as possible, al- 

 lowing a minimum depth of 5 m for the seiner; the 

 skiff would extend the net toward shore. A third set 

 was executed at midreservoir. Sampling continued 



5 Sims, C. W., J. G. Williams. D. A. Faurot, R. C. Johnsen, and D 

 A. Brege. 1981. Migrational characteristics of juvenile salmon 

 and steelhead in the Columbia River Basin and related pas- 

 sage research at John Day Dam, Vols. I and II. Northwest Fish. 

 Sci. Cent., Natl. Mar. Fish. Serv., Seattle, WA 98112-2097 Re- 

 port to U.S. Army Corps of Engineers, 61 p. 



8 Sims. C. W., A. E. Giorgi, R. C. Johnsen, and D. A. Brege. 1983. 

 Migrational characteristics of juvenile salmon and steelhead 

 in the Columbia River Basin — 1982. Northwest Fish. Sci. Cent., 

 Natl. Mar. Fish. Serv., Seattle, WA 98112-2097. Report to U.S. 

 Army Corp of Engineers, 35 p. 



throughout the summer and autumn until late No- 

 vember each year. Sampling extended from the fore- 

 bay at John Day Dam ( rkm 348 ) to the McNary Dam 

 tailrace (rkm 467). We initially established and 

 sampled nine transects spanning the length of the 

 reservoir (Fig. 1). However, catches were so small at 

 the three locations farthest upstream that we dis- 

 continued sampling those sites halfway through the 

 1981 sampling period. We cycled through all 

 transects approximately every other week. All fish 

 were anesthetized with MS-222, counted, and exam- 

 ined for marks. Unmarked fish were freeze branded, 

 a subsample was measured for fork length, and af- 

 ter processing, all fish were allowed to recover from 

 the anesthetic and were released. 



To examine the effects of several key variables on 

 migration rate from McNary to John Day Dam, we 

 used correlation and regression techniques, analyz- 

 ing each year separately and pooled together. The 

 dependent variable was the median migration time 

 (travel time) for each release group. The indepen- 

 dent variables included release date, water tempera- 

 ture, and inverse river-flow volume. We used the in- 

 verse of volume, based on the hypothesis that fish 

 would most likely respond to water velocity (water 

 velocity is the river-flow volume divided by the cross- 

 sectional area) and that fish travel time is related to 

 water particle travel time, which is functionally in- 

 versely related to water velocity. Water temperature 

 and flow were represented by a daily average over 

 the 10-day period following the release date of each 

 marked group. Water temperature and flow data 

 were acquired from the COE. All data were originally 

 reported by Giorgi et al. 7 



Results 



Migration timing and migrant size 



Each year, there was a minor peak in abundance of 

 zero-age chinook salmon passing McNary Dam near 

 the beginning of July and a major peak at the end of 

 July (Fig. 2). In 1982 and 1983, the migration times 

 for the zero-age chinook salmon populations passing 

 John Day Dam were nearly identical. In 1982, 90% 

 of the outmigrants had passed John Day Dam by the 

 week ending 4 September and in 1983, by 26 August. 

 In 1981, the passage distribution was somewhat dis- 

 similar to those of 1982 and 1983; however, the 90th 

 percentile of passage occurred during the week end- 



Giorgi. A. E., D. R. Miller, and B. R Sandford. 1990. Migratory 

 behavior and adult contribution of summer outmigrating 

 subvearling chinook salmon in John Day Reservoir. Northwest 

 Fish. Sci. Cent., Natl. Mar. Fish. Serv., Seattle, WA 98112-2097. 

 Report to Bonneville Power Administration, 68 p. 



