Mid-Columbia Steelhead Adult Abundance Monitoring Designs
Spatial Designs
Temporal Designs
Response Designs
Inference Designs
Evaluation Thresholds
References
Spatial Design
Different designs are used for different populations in the Mid-Columbia steelhead DPS.
Fifteenmile:
A probability design is has been used to make estimates for a portion of the spawning habitat since 2003.
These results are used to estimate spawning activity in unsurveyed streams. Sites are selected
randomly from five-mile survey units stratified across the currently known spawning habitat in Fifteenmile,
Ramsey, Eightmile, and Fivemile Creeks. In 2011 a weir trap was installed and captured fish were PIT
tagged to estimate abundance of adult steelhead using mark-recapture techniques.
West Deschutes:
Abundance estimates for the Deschutes River Westside population of adult spawning steelhead are the
sum of abundance estimates for three components of the population:
Warm Springs River: Census counts of steelhead passed upstream at the Warm Springs National Fish
Hatchery (NFH).
Shitike Creek: Observed redd densities (redds/m2) in index reaches were used to estimate redd
densities in unsurveyed areas.
Mainstem Deschutes (Trout Creek upstream to Pelton Reregulation Dam): Expanded redds from aerial
and boat surveys.
East Deschutes:
An index including all major spawning areas (MaSAs) of Trout, Bakeoven, and Buck Hollow creeks was
expanded to unsurveyed areas of current spawning habitat.
John Day populations:
Annual estimates of the number of spawning steelhead are generated by expanding from index redd
counts. Methods were modified in 2004 to adopt a Generalized Random Tessellation Stratified (GRTS)
design. The design is similar to that created for Oregon coast coho (Stevens, 2002). A GIS coverage of
streams was used as a frame for the population. GRTS designs achieve a spatially-balanced random
point distribution (Stevens, 1997; Stevens & Olsen, 1999; Stevens & Olsen, 2003; Stevens and Olsen,
2004). Inference is made for Independent Populations.
John Day River Index Areas:
Lower Mainstem JDR
Middle Fork JDR
Bear Creek
Beaver Creek
Kahler Creek
Camp Creek
Parrish Creek
Deep Creek
Pine Creek
Lick Creek
Thirtymile Creek
Upper Mainstem JDR
Belshaw Creek
Bear Creek
Beech Creek
East Fork Beech Creek
Canyon Creek
Middle Fork Canyon Creek
McClellan Creek
Riley Creek
Tinker Creek
Temporal Design
Fifteenmile Design:
Random sites are selected independently every year.
John Day GRTS Design:
A rotating panel design consisting of three panels is used. The first panel has 17 sites which are visited
annually (within the year, sites are typically visited multiple times). The second panel has 16 sites which
are repeated one year in every four years. The third panel has 17 sites which are drawn new each year.
Sites in the latter two panels are also typically visited multiple times over the course of a year.
All other designs:
The same areas are surveyed every year.
Response Design
Fifteenmile:
Since 2003, spawning ground surveys have been conducted in three passes over the duration of annual
spawning activity in one-mile survey sites. Surveyors walk stream segments and count redds. In 2011 a
weir trap was installed. All adults contacted at the weir receive a PIT tag and hatchery strays are
excluded from the stream. PIT-tag detection arrays were placed at the confluences of Eightmile and
Fifteenmile Creek, Fivemile and Eightmile Creeks, and Fifteenmile and Ramsey Creeks in 2011. By
2012, a total of five PIT-tag detection arrays will be operational and allow determination of the return of
steelhead to surveyed reaches, including Ramsey, Eightmile, Fifteenmile, Fivemile, Dry, and Pine Creek
drainages
West Deschutes:
Fish are counted at the Warm Springs NFH for the Warm Springs River. Surveyors walk stream
segments and count redds in Shitike Creek. Redd density is calculated by dividing the total number of
redds observed by the area surveyed measured in square meters (redds/m2). Redds are counted in
aerial and boat surveys in the Mainstem Deschutes.
East Deschutes:
Single pass index spawning ground surveys are conducted in the major spawning areas (MaSAs) of
Trout, Bakeoven, and Buck Hollow creeks. Surveyors walk stream segments and count redds. Redd
density is calculated by dividing the total number of redds observed by the area surveyed measured in
square meters (redds/m2). In 2009 a weirs were installed in Bakeoven and Buck Hollow Creeks, and in
2010 a weir was installed in Trout Creek.
John Day populations:
Index areas are sampled annually. Surveyors walk stream segments and count redds.
Inference Design
Fifteenmile:
Observations of redds were expanded by the sample rate, both temporally and spatially, to estimate each
season’s total redds (redds/total spawning area/year). Average proportional relationships relative to the
Fifteenmile Creek mainstem were used to estimate spawning activity in unsurveyed streams (Fivemile
Creek redds represent approximately 15% of the Fifteenmile Creek mainstem redds). Conversion of an
annual total redd count to the adult population from 1985 to present assumes there are 2.1 fish per redd.
This estimate was developed based on data from Deer Creek, a tributary to the Wallowa River in the
Grande Ronde system.
In 2011 a weir trap was installed to estimate abundance of adult steelhead using mark-recapture
techniques in order to further validate redd-count data and the conversion rate. This provides an
additional mark-recapture estimate from returning adult steelhead that were tagged as outmigrant
juveniles, by using the estimated smolt abundance for each outmigrant year.
West Deschutes River:
Abundance estimates for the Deschutes River Westside population of adult spawning steelhead are the
sum of abundance estimates for three components of the population:
Warm Springs River: Census counts at Warm Springs NFH of steelhead passed upstream.
Shitike Creek: Observed redd densities (redds/m2) in index reaches were used to estimate redd
densities in unsurveyed areas. Variability in habitat quality and capacity throughout reaches in Shitike
Creek is accounted for by using the ICTRT’s historical intrinsic potential. The ICTRT intrinsic potential
analyses were used to estimate redds per weighted m 2 of habitat in surveyed reaches. To estimate total
redds in the population we divided observed redds by the proportion of currently occupied habitat
surveyed (weighted m2) in Shitike Creek (ICTRT 2007). An expansion of 2.1 fish per redd was used to
estimate annual spawner abundance. This estimate was derived for summer steelhead in Deer Creek, a
tributary of the Wallowa River. Proportions of hatchery fish observed at the Warm Springs NFH are used
to estimate hatchery proportions in the other areas of the population.
Mainstem Deschutes (Trout Creek upstream to Pelton Reregulation Dam): Expanded redds from aerial
and boat surveys.
East Deschutes River:
Estimates of the abundance of steelhead in the tributary production areas of the Eastside population are
based on single pass index spawning ground surveys in the major spawning areas (MaSAs) of Trout,
Bakeoven, and Buck Hollow creeks. To estimate spawning abundance, observed redd densities
(redds/m2) were extrapolated to unsurveyed areas of currently occupied spawning habitat. Variability in
spawning habitat quality and capacity are incorporated in the abundance estimate by using the ICTRT’s
historical intrinsic potential (ICTRT 2007) to expand redd observations per unit survey area to
unsurveyed areas. Redds are expanded to fish by multiplying total redds by 2.1 fish per redd, derived
from summer steelhead in Deer Creek, a tributary of the Wallowa River. When no spawning surveys
occurred in a particular creek, the average ratio of Trout Cr to Buck Hollow and Bakeoven is used to
produce an estimate. The previous assumption was that redd density observed in Buck Hollow and
Bakeoven was the same as in Trout Creek.
In 2009 a weirs were installed in Bakeoven and Buck Hollow Creeks, and in 2010 a weir was installed in
Trout Creek. These will be used to validate single-pass redd surveys, in addition to providing a markrecapture estimate of escapement of adult steelhead into these tributaries. Hatchery fraction will also be
known from the ratio of marked to unmarked steelhead encountered at the weirs that are kelts. Hatchery
steelhead will be removed from Bakeoven and Trout Creek at the weirs, but allowed to spawn in Buck
Hollow Creek as a part of a BPA funded study (contract 48830).
Trout Creek hatchery fraction estimates were revised downward based on new data summaries from
BPA-funded Trout Creek project (contracts 37576 and 41577). Updates after 2005 use trap counts
instead of spawning ground observations. Trends in Trout Creek hatchery fraction do not closely follow
Buck Hollow and Buckoven and are considerably lower.
For years when at least ten fish were examined for the presence of adipose fins in each stream, the
marked fish proportion was used for the hatchery fraction. For years when fewer than ten fish were
observed, the hatchery fraction was estimated based on the average ratio of the percentage of hatchery
fish at Sherars Falls and the percentage of hatchery fish on the spawning grounds in Buckhollow and
Bakeoven Creeks across all years. For Trout Creek we used the relationship of hatchery fraction
between Trout Creek and Warm Springs National Fish Hatchery.
John Day populations:
Annual estimates of the number of spawning steelhead are generated by expanding from index redd
counts.
The recommended estimator for the GRTS design in the John Day basin is the Horvitz-Thompson or πestimator. Briefly, the estimator weights the observation collected at si by the reciprocal of the inclusion
density function π(si). Annual status estimates are obtained from all sites visited in that year. The design
selects points on streams. Suppose point si falls on a stream segment with length li. The observation
collected represents an aggregate over the entire length of the segment. Thus, if the observation is
spawner count, then the entire segment is examined for spawners, and all spawners in the segment are
counted. Let yi be the aggregated observation. Then an estimator of the total number of spawners over
the entire stream network is
where n is the number of samples. Moreover, within an assessment unit, π(s) is constant, so, letting
, the estimator becomes
.
Refer to epa.gov/nheerl/arm for R scripts (spsurvey library; function CDF.compute) to calculate
population abundance estimates and confidence intervals.
Comparison with recent GRTS sampling results (probabilistic sampling scheme) indicates that average
redd densities across spawning habitats within the John Day MPG populations are consistently lower
than average density across the selected index areas (2004/2005 ratio of GRTS reach average density to
index reach density = 0.335).
The total population of redds in a given year is estimated as total spawning miles (742.1 based on EDT
input data) X index density X annual GRTS/Index average density ratio. This is converted to an estimate
of spawners by multiplying by 2.1 spawners per redd (derived from weir count/redd count comparisons
for Deer Creek in the Grande Ronde system). It is planned to switch to annual fish per redd estimates for
years when the Deer Creek sampling data are available in the next update.
The proportion of natural-origin fish found on the spawning grounds is multiplied by the total estimate to
determine the estimate of natural-origin (wild) fish. Estimates of Hatchery/Wild composition are based
on aggregate sampling for populations upstream of Lower Mainstem John Day including observations of
adipose clips during spawning surveys (1992 to present) and rotary screw trap/seine collection of adults
(2000 to present).
References
Stevens, D.L., Jr. (1997). .Variable density grid-based sampling designs for continuous spatial populations’.
Environmetrics 8: 167-195.
Stevens, D.L. (2002). Sampling design and statistical analysis methods for integrated biological and physical
monitoring of Oregon streams. OPSW-ODFW-2002-07, Oregon Department of Fish and Wildlife,
Portland, Oregon.
Stevens, Jr., D. L. and A. R. Olsen. (1999). .Spatially Restricted Surveys Over Time for Aquatic Resources.
Journal of Agricultural, Biological, and Environmental Statistics 4:415-428.
Stevens, Jr., D. L. and A. R. Olsen. (2004). .Spatially Balanced Sampling of Natural Resources. Journal of the
American Statistical Association 99:262-278.
Stevens, Jr. D.L., and N.S. Urquhart. (2000). Response Designs and Support Regions in Sampling Continuous
Domains. Environmetrics 11:13-41.
Stevens, Jr., D.L., and A. R. Olsen. (2003). .Variance Estimation for Spatially Balanced Samples of Environmental
Resources. Environmetrics 14:593-610.
Current Status Reviews: Interior Basin Salmon and Steelhead ESUs. Volume III. Mid-Columbia River Steelhead DPS.
ICTRT, 2009.
Abundance and Productivity of Fifteenmile Creek Steelhead (2011) Report to the US Department of Energy,
Bonneville Power Administration Project # 2010-035-01.