Evaluating Smolt Release Timing for Improved Adult Returns of Chinook Salmon
This evaluation study assesses the impact of smolt release timing on juvenile migration, fish health, and adult returns of Spring Chinook Salmon. It explores the reasons for low SAR rates in the Clearwater River basin compared to other basins, discusses release timing history, and presents methods involving two release times for evaluation. Historic release time evaluations and recovery data are also analyzed.
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Presentation Transcript
An Evaluation of smolt release timing to Improve Adult Returns of Spring Chinook Salmon Adults Chris Noyes, IDFG Bill Young, NPT/IFWCO LSRCP Annual Meeting 2024 Boise, ID U.S. Fish and Wildlife Service emblem
Objectives Determine the affects of release timing on: Juvenile migration Fish health Adult returns
Justification Low SAR rates of Clearwater River releases relative to other basins Salmon Basin Clearwater Basin PAHP 0.027 0.056 0.152 0.080 0.088 0.214 0.170 0.112 SAW 0.128 0.068 0.292 0.264 0.753 0.627 0.415 0.364 RR 0.184 0.232 0.370 0.483 0.669 1.435 1.080 0.636 KNOXB 0.045 0.279 0.469 0.212 0.656 0.932 0.506 0.443 Powell Selway Clear Creek Red River NF Clwtr DWOR Kooskia Year 2018* 2017 2016 2015 2014 2013 2012 0.107 0.067 0.466 0.376 0.423 1.021 0.410 0.410 0.050 0.322 0.480 0.295 0.439 0.787 0.949 0.475 0.082 0.195 0.394 0.248 0.851 0.682 0.979 0.490 0.109 0.135 0.286 0.196 0.211 0.480 0.538 0.279 0.092 0.114 0.458 0.089 0.057 0.130 0.128 0.337 1.064 0.705 0.358 0.115 0.053 0.218 0.271 0.343 1.315 0.572 0.413 Ave
Justification Release timing history DNFH release date 13-Apr 8-Apr 3-Apr 29-Mar 24-Mar 19-Mar 14-Mar
Justification early arrival timing at LGR limited passage routes Hesse, 2017 LSRCP meeting
Methods Hatcheries Dworshak National Fish Hatchery Clearwater Fish Hatchery Nez Perce Tribal Hatchery Two release times Early ( normal ) release in late March Late Release 2 weeks later Metrics Juvenile size/condition at release 20 fpp Juvenile survival and travel time to LGR PIT tags Fish health evaluations Adult returns Evaluated by PBT
Historic release time evaluations Release CWT recoveries II-Salts III-SaltsTotal Percent recovery Hatchery Year Date Timing CWT # TT to LGR I-Salts rtns 4/7 4/22 5/5 4/8 4/22 5/6 4/8 4/22 5/6 Early Mid Late Early Mid Late Early Mid Late 111,879 113,423 97,637 121,929 119,297 105,988 66,014 61,840 68,211 16 13 12 23 13 10 25 18 11 4 0 0 1 0 1 11 4 1 17 4 1 15 6 3 37 24 27 1 1 0 1 1 0 22 5 1 17 7 4 48 28 28 0.020% 0.004% 0.001% 0.014% 0.006% 0.004% 0.073% 0.045% 0.041% 1992 Kooskia 1993 Dworshak 1994
Results to Date Travel Times Arrival Times Juvenile Survival to Lower Granite Adult Returns Only one year of adult returns so far
Travel Time to Lower Granite Similar patterns between groups in 2021 and 2022 Earlier migrating fish tend to travel slower Much more variability in 2023
Passage Timing at Lower Granite Dam 100 80 MY 2021 Percent 60 40 Passage Timing at Lower Granite Clearwater 20 0 Dworshak 4/1 4/8 4/15 4/22 4/29 5/6 5/13 5/20 5/27 Migration Year Release Date 3/31/2021 4/16 4/14/2021 4/25 3/31/2022 4/16 4/14/2022 4/21 3/30/2023 4/08 4/13/2023 4/17 100 10% 50% 4/26 4/29 4/29 4/29 4/17 4/29 90% 5/17 5/09 5/05 5/05 5/03 5/04 10% 4/19 4/26 4/20 4/27 4/08 4/23 50% 4/29 5/03 4/30 5/02 4/15 5/02 90% 5/11 5/15 5/08 5/09 5/05 5/12 MY 2022 80 Percent 60 40 2021 20 0 4/1 4/8 4/15 4/22 4/29 5/6 5/13 5/20 5/27 2022 100 80 MY 2023 Percent 2023 60 40 20 0 4/1 4/8 4/15 4/22 4/29 5/6 5/13 5/20 5/27 Clearwater - Early Clearwater - Late Dworshak - Late Dworshak - Early
Travel Time to Lower Granite Flows were generally higher in 2023 during passage period
Survival to Lower Granite Survival is generally high (>80%) Late release groups had higher survival to Granite (except Clearwater in 2021) Differences not statistically significant
Adult Returns to Lower Granite A few caveats Clearwater Number of Fish BY2019 72 37 Dworshak Number of Fish BY2019 98 75 PBT sampling at Lower Granite Individual samples SAR s can only be evaluated within the study BY 2019 from Clearwater Hatchery confounded BY 2020 represents very few fish BY2020 1 4 BY2020 3 12 Early Late Clearwater SAR's Dworshak SAR's BY2019 0.019% 0.019% BY2020 0.0004% 0.0017% BY2019 0.010% 0.011% BY2020 0.0003% 0.0010% Early Late
