Investigations into the Early Life-history of Naturally Produced Spring Chinook Salmon and Summer Steelhead in the Grande Ronde River Basin, Annual Report 2001. Page: 4 of 128
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ABSTRACT
We determined migration timing and abundance of juvenile spring chinook salmon
Oncorhynchus tshawytscha and juvenile steelhead/rainbow trout Oncorhynchus mykiss using
rotary screw traps on four streams in the Grande Ronde River basin during the 2001 migratory
year (MY 2001) from 1 July 2000 through 30 June 2001. Based on migration timing and
abundance, two distinct life-history strategies of juvenile spring chinook and O. mykiss could be
distinguished. An 'early' migrant group left upper rearing areas from 1 July 2000 through 29
January 2001 with a peak in the fall. A 'late' migrant group descended from upper rearing areas
from 30 January 2001 through 30 June 2001 with a peak in the spring. The migrant population
of juvenile spring chinook salmon in the upper Grande Ronde River in MY 2001 was very low in
comparison to previous migratory years. We estimated 51 juvenile spring chinook migrated out
of upper rearing areas with approximately 12% of the migrant population leaving as early
migrants to overwinter downstream. In the same migratory year, we estimated 16,067 0. mykiss
migrants left upper rearing areas with approximately 4% of these fish descending the upper
Grande Ronde River as early migrants. At the Catherine Creek trap, we estimated 21,937
juvenile spring chinook migrants in MY 2001. Of these migrants, 87% left upper rearing areas
early to overwinter downstream. We also estimated 20,586 0. mykiss migrants in Catherine
Creek with 44% leaving upper rearing areas early to overwinter downstream. At the Lostine
River trap, we estimated 13,610 juvenile spring chinook migrated out of upper rearing areas with
approximately 77% migrating early. We estimated 16,690 0. mykiss migrated out of the Lostine
River with approximately 46% descending the river as early migrants. At the Minam River trap,
we estimated 28,209 juvenile spring chinook migrated out of the river with 36% migrating early.
During the same period, we estimated 28,113 0. mykiss with approximately 14% of these fish
leaving as early migrants.
Juvenile spring chinook salmon PIT-tagged at trap sites in the fall and in upper rearing
areas during winter were used to compare migration timing and survival to Lower Granite Dam
of the early and late migrant groups. Juvenile spring chinook tagged on the upper Grande Ronde
River were detected at Lower Granite Dam from 4 May to 20 May 2001, with a median passage
date of 17 May. Too few fish were collected and tagged to conduct detection rate and survival
comparisons between migrant groups. PIT-tagged salmon from Catherine Creek trap were
detected at Lower Granite Dam from 27 April to 13 July 2001. Early migrants were detected
significantly earlier (median = 10 May) than late migrants (median = 1 June). Also, early
migrants from Catherine Creek were detected at a significantly higher rate than fish tagged in
upper rearing areas in the winter, suggesting better survival for fish that migrated out of upper
rearing areas in the fall. Juvenile spring chinook salmon from the Lostine River were detected at
Lower Granite Dam from 2 April through 4 July 2001. Early migrants were detected
significantly earlier (median = 27 April) than late migrants (median = 14 May). However, there
was no difference in detection rates between early and late migrants. Survival probabilities
showed similar patterns as dam detection rates. Juvenile spring chinook salmon from the Minam
River were detected at Lower Granite Dam from 8 April through 18 August 2001. Early
migrants were detected significantly earlier (median = 28 April) than late migrants (median = 14
May). Late migrants from the Minam River were tagged at the trap in the spring.
Spring chinook salmon parr PIT-tagged in summer 2000 on Catherine Creek and thei
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Reischauer, Alyssa; Monzyk, Frederick & Van Dyke, Erick. Investigations into the Early Life-history of Naturally Produced Spring Chinook Salmon and Summer Steelhead in the Grande Ronde River Basin, Annual Report 2001., report, June 1, 2003; Portland, Oregon. (https://digital.library.unt.edu/ark:/67531/metadc932875/m1/4/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.