Naches Bull Trout Population Group: Difference between revisions
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''These three populations make use of shared foraging, migration, and overwintering (FMO) habitat in the Naches River, and historically may have mixed with Upper Yakima and Tieton River populations before dams blocked migration corridors in the early 1900s. Naches fluvial bull trout may also utilize the mainstem Yakima river upstream and downstream of the confluence with the Naches River when temperatures are suitable. Information on conditions, threats and actions for this shared FMO habitat are detailed in the [[Naches River FMO Habitat]] page.'' | ''These three populations make use of shared foraging, migration, and overwintering (FMO) habitat in the Naches River, and historically may have mixed with Upper Yakima and Tieton River populations before dams blocked migration corridors in the early 1900s. Naches fluvial bull trout may also utilize the mainstem Yakima river upstream and downstream of the confluence with the Naches River when temperatures are suitable. Information on conditions, threats and actions for this shared FMO habitat are detailed in the [[Naches River FMO Habitat]] page.'' | ||
The Little Naches River watershed is large and contains apparently suitable bull trout habitat in streams other than Crow Creek and many surveys have been conducted in the Little Naches River and various tributaries over the years (USFS 1996a<ref>USFS. ''Cle Elum Ranger District 1996 Electroshocking Data and South Fork Little Naches Report''. U.S. Forest Service, Wenatchee National Forest, Cle Elum Ranger District, 1996, <nowiki>https://ybfwrb.org/wp-content/uploads/2017/10/USFS_1996a.pdf</nowiki>.</ref>, Reiss 2008<ref>Reiss, K. Y. ''SF Little Naches Snorkel Surveys''. Naches Ranger District, Okanogan-Wenatchee National Forest, 2008, <nowiki>https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_2008.pdf</nowiki>.</ref>, Kline 2024<ref name=":2">Kline, Scott. ''2024 NF Little Naches Demographic and eDNA Survey Results''. WDFW, 2024, <nowiki>https://ybfwrb.org/wp-content/uploads/2025/02/2024-NF-Little-Naches-demographic-and-eDNA-survey-results.docx</nowiki>.</ref>). There have been individual bull trout sightings reported throughout the Little Naches stream network but their origin is unknown (Anderson 2010<ref>Anderson, E. ''Bull Trout Sightings Compiled by Eric Anderson for Yuki Reiss''. 25 Oct. 2010, <nowiki>https://ybfwrb.org/wp-content/uploads/2017/10/Anderson_2010.xlsx</nowiki>.</ref>). ''In 2018 eDNA samples were collected in the middle and north forks of the Little Naches River in an attempt to understand if there was a spawning population. A few samples returned as positive, yet bull trout had still not been physically observed. In 2024 WDFW followed up with a demographic survey in the North Fork Little Naches and more eDNA samples in the north and middle forks. No bull trout were observed over | The Little Naches River watershed is large and contains apparently suitable bull trout habitat in streams other than Crow Creek and many surveys have been conducted in the Little Naches River and various tributaries over the years (USFS 1996a<ref>USFS. ''Cle Elum Ranger District 1996 Electroshocking Data and South Fork Little Naches Report''. U.S. Forest Service, Wenatchee National Forest, Cle Elum Ranger District, 1996, <nowiki>https://ybfwrb.org/wp-content/uploads/2017/10/USFS_1996a.pdf</nowiki>.</ref>, Reiss 2008<ref>Reiss, K. Y. ''SF Little Naches Snorkel Surveys''. Naches Ranger District, Okanogan-Wenatchee National Forest, 2008, <nowiki>https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_2008.pdf</nowiki>.</ref>, Kline 2024<ref name=":2">Kline, Scott. ''2024 NF Little Naches Demographic and eDNA Survey Results''. WDFW, 2024, <nowiki>https://ybfwrb.org/wp-content/uploads/2025/02/2024-NF-Little-Naches-demographic-and-eDNA-survey-results.docx</nowiki>.</ref>). There have been individual bull trout sightings reported throughout the Little Naches stream network but their origin is unknown (Anderson 2010<ref>Anderson, E. ''Bull Trout Sightings Compiled by Eric Anderson for Yuki Reiss''. 25 Oct. 2010, <nowiki>https://ybfwrb.org/wp-content/uploads/2017/10/Anderson_2010.xlsx</nowiki>.</ref>). ''In 2018 eDNA samples were collected in the middle and north forks of the Little Naches River in an attempt to understand if there was a spawning population. A few samples returned as positive, yet bull trout had still not been physically observed. In 2024 WDFW followed up with a demographic survey in the North Fork Little Naches and more eDNA samples in the north and middle forks. No bull trout were observed over 8 nights of snorkeling and the eDNA sample results were negative for bull trout (Kline 2024''<ref name=":2" />'').'' | ||
== Population Genetics == | == Population Genetics == | ||
Revision as of 14:35, 7 April 2025
Overview
The Naches Population Group consists of three fluvial bull trout populations. Detailed information on each can be found here:
American River Bull Trout Population
Crow Creek Bull Trout Population
Rattlesnake Creek Bull Trout Population
These three populations make use of shared foraging, migration, and overwintering (FMO) habitat in the Naches River, and historically may have mixed with Upper Yakima and Tieton River populations before dams blocked migration corridors in the early 1900s. Naches fluvial bull trout may also utilize the mainstem Yakima river upstream and downstream of the confluence with the Naches River when temperatures are suitable. Information on conditions, threats and actions for this shared FMO habitat are detailed in the Naches River FMO Habitat page.
The Little Naches River watershed is large and contains apparently suitable bull trout habitat in streams other than Crow Creek and many surveys have been conducted in the Little Naches River and various tributaries over the years (USFS 1996a[1], Reiss 2008[2], Kline 2024[3]). There have been individual bull trout sightings reported throughout the Little Naches stream network but their origin is unknown (Anderson 2010[4]). In 2018 eDNA samples were collected in the middle and north forks of the Little Naches River in an attempt to understand if there was a spawning population. A few samples returned as positive, yet bull trout had still not been physically observed. In 2024 WDFW followed up with a demographic survey in the North Fork Little Naches and more eDNA samples in the north and middle forks. No bull trout were observed over 8 nights of snorkeling and the eDNA sample results were negative for bull trout (Kline 2024[3]).
Population Genetics
The genetic composition of Naches River fluvial bull trout populations, including Rattlesnake, Crow, and American/Union/Kettle, reflects gene flow among populations (Small et al. 2009[5]). Most individuals in these populations were assigned to a single genetic cluster with over 90% ancestry, but several individuals displayed mixed ancestry, indicating interpopulation mixing. For example, in the American and Union populations, 8 out of 52 fish had ancestry linked to Rimrock basin fish, suggesting historical spawning events. Crow Creek fish exhibited significant ancestry from Rattlesnake-origin fish, while some Rattlesnake fish had ancestry from American-Union, Crow, SF Tieton, and Indian Creek. Additionally, a few Rattlesnake individuals showed strong ancestry (>94–97%) from SF Tieton and NF Tieton populations, indicating emigration or one-way gene flow due to entrainment (Small et al. 2009[5]).
Population Monitoring
An early 2000s study captured bull trout using hook-and-line as well as weir and box traps (Mizell and Anderson 2010[6]). Sixty-two bull trout were radio-tagged in the Naches drainage. Of the 62 bull trout tagged in the Naches drainage; 29 were captured from various holding pools in the main stem Naches, 16 from the Tieton River below Rimrock Reservoir (Tieton Dam), seven from Rattlesnake Creek, three from the Bumping River, two from the American River and five from Union Creek (American River tributary). The researchers radio tracked bull trout from September 2003 through December 2006. DNA samples were taken and each fish was genetically assigned to a population. The results showed that bull trout move very little during the winter season once they settle into a preferred holding pool (Mizell and Anderson 2010[6]). Summer movements toward spawning areas occurred from May through August, depending on where the spawning tributary was located. Some individuals stayed in the mainstem Naches river throughout the year without migrating to a spawning tributary.
Naches fluvial bull trout spawning is monitored yearly via two to three passes of redd surveys. Other population monitoring has not occurred for these populations.
Note Cowiche Controversy- not further addressed as BT population areas
References
- ↑ USFS. Cle Elum Ranger District 1996 Electroshocking Data and South Fork Little Naches Report. U.S. Forest Service, Wenatchee National Forest, Cle Elum Ranger District, 1996, https://ybfwrb.org/wp-content/uploads/2017/10/USFS_1996a.pdf.
- ↑ Reiss, K. Y. SF Little Naches Snorkel Surveys. Naches Ranger District, Okanogan-Wenatchee National Forest, 2008, https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_2008.pdf.
- ↑ 3.0 3.1 Kline, Scott. 2024 NF Little Naches Demographic and eDNA Survey Results. WDFW, 2024, https://ybfwrb.org/wp-content/uploads/2025/02/2024-NF-Little-Naches-demographic-and-eDNA-survey-results.docx.
- ↑ Anderson, E. Bull Trout Sightings Compiled by Eric Anderson for Yuki Reiss. 25 Oct. 2010, https://ybfwrb.org/wp-content/uploads/2017/10/Anderson_2010.xlsx.
- ↑ 5.0 5.1 Small, M. P., et al. WDFW Yakima Bull Trout Report. Phase 3: Genetic Analysis of Yakima Basin Bull Trout (Salvelinus Confluentus). Washington Department of Fish and Wildlife, 2009, https://ybfwrb.org/wp-content/uploads/2017/10/Small_et_al_2009.doc.
- ↑ 6.0 6.1 Mizell, M., and E. Anderson. An Investigation into the Migratory Behavior, Habitat Use and Genetic Composition of Fluvial and Resident Bull Trout (Salvelinus Confluentus) in the Yakima River Basin + Appendices. Washington Department of Fish and Wildlife, 2010, https://ybfwrb.org/wp-content/uploads/2017/10/Mizell_Anderson_2010.pdf.