Rattlesnake Creek Bull Trout Population

Overview

Rattlesnake Creek is a right-bank tributary of the Naches River, which originates in the William O. Douglas Wilderness Area and is approximately 20 miles in length from its origin to its confluence with the Naches River at RM 28. The north fork is much shorter and appears impassable for fish a short distance upstream of the confluence of the two forks. Several small tributaries enter the south fork along its course, including Little Wildcat, Shell, Dog and Hindoo creeks. Little Rattlesnake Creek enters well below the forks about a mile above the mouth of Rattlesnake Creek.

Population Distribution and Life History

Rattlesnake Creek supports a single local population of bull trout, which displays a fluvial life history type; a resident component may exist as well but this has not been confirmed. The primary spawning area for this population is located in the south fork above the wilderness boundary at RM 14 and extends about seven miles upstream; it includes Little Wildcat and Shell creeks (Figure 5) Keep track of figures / appendix information while transferring to online version. Juvenile bull trout are assumed to rear in Rattlesnake Creek all the way down to the mouth; adult FMO habitat is primarily the Naches River below the Rattlesnake confluence but some adults also utilize FMO habitat upstream (Mizell and Anderson 2010). An unknown but assumed small number of adult bull trout evidently migrate up the Tieton River and the mainstem Yakima River as well (see Population Monitoring below). Adult bull trout migrate into Rattlesnake Creek in late June and July and are in close proximity to their spawning grounds by mid-August.

Status and Trends

Status

The USFWS (1998) did not consider the Rattlesnake Creek population singularly but considered the Naches River “subpopulation” (i.e., all three Naches River fluvial populations) to be depressed with an unknown trend. WDFW similarly lumped the Naches River fluvial populations and rated the status of this stock as critical (WDFW 2004).

Results of genetic analyses show this population is genetically distinct from all other Yakima Basin populations but did cluster with the other Naches River fluvial populations, indicating some degree of gene flow either currently or historically (Reiss 2003 (reference not in Zotero); Small et al. 2009). Juvenile samples for the genetic baseline were collected in spawning and rearing areas above the wilderness boundary on Rattlesnake Creek, and adults were collected in a box trap post-spawning during the radio telemetry studies (Mizell and Anderson 2010). No samples were collected in the smaller tributaries.

Trends

The Rattlesnake Creek population spawns primarily during the month of September. Complete redd surveys have been conducted for this population since 1996 in an index area beginning about 2.8 river miles above the wilderness boundary and extending upstream 7.1 miles; also surveyed are 0.1 mile of Shell Creek and 0.5 mile of Little Wildcat Creek. This index area is believed to cover the entirety of the spawning habitat currently utilized. Annual redd counts have been highly variable with counts ranging from 13 to 69 (Figure 4). In 2021 redd surveys were limited due to the Schneider Springs wildfire, which burned a significant portion of the Rattlesnake Creek drainage.

Link/iframe to WDFW SalmonSource??

This majority of this narrative fits more appropriately with "population monitoring" except for the numbers for annual redd counts. Lacking a narrative / statement about the long term trend.

Population Monitoring

The USFWS first documented the presence of bull trout (although they called them Dolly Varden) during habitat and fish barrier surveys conducted during 1935-1936 (McIntosh 1990). A survey by the Washington Department of Game Fisheries Research Team in 1975 also documented bull trout (Dolly Varden) (Washington Dept of Game 1975). The population was not investigated again until WDFW captured several juvenile bull trout in Rattlesnake Creek during electroshocking surveys (Anderson 1991). Exploratory spawning surveys were first conducted in 1994 with complete surveys initiated in 1996. In 2001 juvenile bull trout were captured in the creek during snorkel surveys conducted in association with the collection of genetic samples (Reiss 2003 (reference not in Zotero)).

Mizell and Anderson (2010) investigated the migratory behavior of bull trout in the Naches River and its tributaries. They reported on migration timing and overwintering habitat. In October after spawning, adults migrate back to the Naches River to over-winter. Although not observed during this radio telemetry study, a few Rattlesnake Creek adults appear to make their way up the Tieton River. Small et al. (2009) reported that six of 34 adult bull trout captured in the stilling basin directly below Tieton dam, most during a fish salvage operation in December 2005, genetically assigned to the Rattlesnake Creek population. Evidence that Naches River fluvial bull trout may use FMO habitat in the mainstem Yakima River comes from a single bull trout that was sampled at Roza Dam in 2005, which also genetically assigned to the American River population (see Appendix C). Note - How to upload / present Appendix info in wiki?

Attempting to determine the complete distribution of bull trout in the Rattlesnake Creek watershed, WDFW also conducted electroshocking surveys on the North Fork Rattlesnake Creek and Little Rattlesnake Creek in 1990 and 1994, finding no bull trout (WDFW 1990). In addition the Forest Service completed night snorkel surveys on this tributary in 2002 using the bull trout presence/absence protocols developed by Peterson et al. (2002). No bull trout were found during these surveys (USFS 2002 - no link or attachment in Zotero). Technicians with YN Coho Program documented subadult bull trout in the lower portion of Little Rattlesnake Creek in 2006 and 2011 (T. Newsome, YN, pers comm.). Due to the absence of bull trout found in the previous surveys, it is assumed this fish belonged to the Rattlesnake Creek population.

Figure 5 shows Rattlesnake Creek Watershed (insert old maps or link to new GIS portal with zoom to population??)