Figure 1. Columbia River Basin showing the study area, 1991.
Figure 2. The study area showing the release locations for subyearling chinook salmon, 1991.
Figure 3. The study area showing the electrofishing transect areas in Tanner Creek and adjacent shoreline areas of the Columbia River, 1991.
Figure 4. Jones Beach, Columbia River, sampling sites. The beach and purse seining areas are denoted by asterisks.
Figure 5. The study area showing northern squawfish catch per unit effort for each electrofishing transect and proportion of tags (representing ingested juvenile salmon) from the 24 June Tanner Creek release group recovered in those northern squawfish, 1991.
Figure 6. Daily recoveries of test fish at Jones Beach (standardized for effort) comparing mid-stream Columbia River to Tanner Creek release groups, 1991.
Figure 7. Daily mean flows of the Columbia River at Bonneville Dam during the estuarine sampling periods, 1989, 1990, and 1991; flow measurements provided by the U.S. Army Corps of Engineers, Portland Oregon.
Figure 8. Daily mean fork lengths of subyearling chinook salmon recovered at Jones beach, comparing mid-stream Columbia River to Tanner Creek release groups, 1991.
Figure 9. Fork length distributions of fish after recovery in the estuary comparing mid-stream Columbia River to Tanner Creek release groups, 1991.
Figure 10. Mean recovery percentages comparing mid-stream Columbia River to Tanner Creek release groups, 1991. Northern squawfish were removed by electrofishing between the two release dates. Recovery rates for the mid-stream release groups were significantly higher (P>0.05) than for the Tanner Creek release groups on both dates.
Figure 11. Movement rate versus survival benefit for mid-stream Columbia River release over Tanner Creek release of subyearling fall chinook salmon, 1989-1991.
Table 1. Summary of releases of marked subyearling chinook salmon, Tanner Creek versus mid-stream Columbia River, 1991.
Table 2. Number of northern squawfish removed by date (all electrofishing sites) and number of coded wire tags recovered in digestive tracts of northern squawfish, release site study 1991.
Table 3. Electrofishing effort, number of northern squawfish removed, and number of coded wire tags recovered from the digestive tracts of northern squawfish, release site study 1991.
Table 4. Movement rates to Jones Beach for marked groups of subyearling chinook salmon released in Tanner Creek and in mid-stream Columbia River, 1989, 1990, and 1991.
Table 5. Recovery percentages of tagged subyearling chinook salmon at Jones Beach, Tanner Creek release versus mid-stream Columbia River release, 1989, 1990, and 1991.
Appendix Table A1. Short-term tag loss estimates for subyearling chinook salmon, 1991.
Appendix Table A2. Tag loss estimates among marked groups of subyearling chinook salmon after a 30-day holding period; Tanner Creek versus mid-stream Columbia River, 1991.
Appendix Table B1. Northern squawfish electrofishing daily effort and catch results, 1991.
Appendix Table B2. Coded wire tags from ingested juvenile salmon recovered in the stomachs of northern squawfish during the electrofishing efforts, 1991.
Appendix Table C1. Daily purse seine and beach seine fishing effort, water temperatures, and Secchi disk transparency measurements at Jones Beach, Tanner Creek versus mid-stream Columbia River, 1991.
Appendix Table C2. Daily recoveries, recoveries standardized for effort, dates of median fish recovery, and movement rates to Jones Beach of marked subyearling chinook salmon released from Bonneville Hatchery into Tanner Creek and transported from the hatchery to mid-stream Columbia River, 1991.
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