Salmon Escapements above Rock Island Dam, 



1954-60 



by 

 Robert R. French and Roy J. Wahle 



ABSTRACT 



This paper summarizes (1) 7 years' data, 1954-60, on the size and timing of 

 salmon and steelhead runs passing Rocky Reach damsite on the Columbia River 

 above Rock Island Dam and (2) the distribution and abundance of salmon in tributary 

 spawning streams. The majority of spring chinook salmon passing Rock Island 

 continue past Rocky Reach and the Wells damsite to spawn in the Methow River 

 system. Most summer chinook salnnon spawn in the Wenatchee River. Sockeye 

 salmon spawn primarily in the Okanogan River in Canada and in the White River in 

 the Wenatchee River system. Length frequency measurements of spawned chinook 

 salmon show that main size groups of probably many age groups are usually present 

 in all tributaries each year. Few unspawned female chinook salmon were observed 

 on the spawning grounds; egg retention was remarkably low among spawned chinook 

 salmon. 



INTRODUCTION 



Salmon spawning streams between Rock 

 Island and Chief Joseph Dams (located on 

 the Columbia River at river miles 453 and 

 546, respectively) were surveyed by Bureau 

 of Commercial Fisheries personnel from 1954 

 through 1960. A major and continuing interest 

 of the surveys was the relative abundance 

 of salmon in the various tributary streams, 

 the spawning times, and specific spawning 

 areas. Results of some of the studies have 

 been published: French and Wahle (1959) re- 

 ported on the salmon runs in the Wenatchee 

 River system for 1955-57 and (1960) on 

 salmon escapements passing the Rocky Reach 

 damsite in 1956-57. 



Interest in the abundance and distribution 

 of these upriver runs of salmon continues 

 because new hydroelectric projects are planned 

 or under construction. In addition to Wells 

 Dam, now being constructed on the Columbia 

 River above Rocky Reach, hydroelectric proj- 

 ects are proposed for the Wenatchee River 

 system, and modifications are planned at 

 existing irrigation dams on the Methow River 

 and at Enloe Dam on the Similkanneen River. 

 All projects require provisions for passing 

 anadromous fish populations. Knowledge of 

 sizes, tinne of passage, and spawning areas 



Note.— Robert R. French and Roy J. Wahle, FUhery 

 BlologlBtB (Research), Bureau of Commercial Fisheries 

 Biological Laboratory, Seattle, Wash. 



of these populations are important for planning 

 project features and operations. 



The purpose of this report is to summarize 

 the distribution and abundance of salmon in 

 tributaries above Rock Island Dam for the 

 7 years, 1954-60, thus providing a record 

 of salmon escapements. Anadromous fish in- 

 vestigated were chinook salmon ( Oncorhynchus 

 tshawytscha ), sockeye salmon (O. nerka) , 

 silver salmon, (O^. kisutch) , and steelhead 

 ( Salnno gairdneri) . 



SIZE AND TIME OF PASSAGE OF RUNS 

 AT ROCKY REACH 



In these investigations we have used the 

 salmon counts at Rock Island Dam and spawn- 

 ing survey counts as the basic data for deter- 

 mining the time of passage and estimating the 

 size of escapements passing RockyReachdam- 

 site (fig. 1). At the time of these studies, 

 the date of passage of runs at Rock Island 

 Dam, 21 miles downstream from Rocky Reach, 

 was regarded as an approximation of the date 

 the runs would pass Rocky Reach. Subsequent 

 comparisons show a 2- to 3-day travel time 

 for all species from Rock Island Dam to 

 Rocky Reach Dam.^ 



Rocky Reach Dam was completed in 1961. 

 ^ Richard L. Major and James L. Mlghell. A study to 

 measure delay to upstream migrating aalmonlds at Rocky 

 Reach Dam. Bureau of Commercial Fisheries Biological 

 Laboratory, Seattle, Wash. [Manuscript.] 



