Lower Columbia Coho Habitat Monitoring Design
Spatial Design
Temporal Design
Response Design
Inference Design
Evaluation Thresholds
References Methods Metadata
Spatial Design
The design is described in detail in Stevens (2002). The sampling is targeted at two spatial
scales: A GIS coverage of all anadromous fish distribution was used as a frame for inference to
Strata. A GIS coverage of the available spawning and rearing habitat for coho salmon was used
to make inference for Populations. The coverages were based on USGS 1:25,000 topographic
maps, modified by ODFW to correspond to the target population of streams for each
population. Data from the population-scale surveys are reported in the Summary and Explorer
tools on this site. Additional data may be available via download. Generalized Random
Tessellation Stratified designs (GRTS) achieve a spatially-balanced random point distribution
(Stevens, 1997; Stevens & Olsen, 1999; Stevens & Olsen, 2003; Stevens and Olsen, 2004)
and this approach was used.
Temporal Design
Population blocks will be sampled once every 5 years starting in 2006, so that every population
will have been sampled by 2011. Sampling order will be randomly determined for each 5 year
period. To balance trend and status detection, 40% of sites within a population block will be
revisited every 5 years and 60% will be visited only once. Following the first 5 years of
population scale habitat surveys, sample size in each population block will be adjusted based
on sensitivity analyses of the habitat variables.
Response Design
Selected sites are visited during summer low flow period (mid-June - September). Surveyors
collect information on channel size, flow, substrate composition, large wood, habitat complexity,
and riparian characteristics. For a full description of the field methods used to conduct the
stream habitat surveys click here. Correlations between summer conditions and winter
conditions were used to estimate winter conditions from summer survey data.
The Habitat Limiting Factors Model (HLFM version 7.0) is used to estimate the capacity of
aquatic habitat to support juvenile coho during the winter. The background, scientific basis, and
application of the HLFM are described in Reeves et al (1989), Nickelson et al. (1992),
Nickelson (1998), and Nickelson and Lawson (1998). Since the publications in 1998, two major
adjustments have been made to the model. The first (version 6) reduced the potential density
that large streams could support. The second modification (version 7) recognized the role that
large complex jams could play in providing refugia for juvenile coho during the winter,
effectively increasing the carrying capacity of a stream. The two adjustments to the model were
based on data collected during the studies referenced above, and ongoing studies within the
coastal coho ESU (e.g. Jepsen and Leader 2008) (T. Nickelson, personal communication).
Inference Design
All available data (from 2006 to present) are pooled to provide an adequate sample size to
make the estimate. The recommended estimator is the Horvitz-Thompson or π-estimator.
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
cumulative distribution functions (cdf) population estimates and confidence intervals.
An error estimate of the miles of high quality habitat in each population unit is based on the
95% confidence interval of the cumulative distribution function (cdf) for winter parr. The point
estimate of high quality miles and 95% C.I. is estimated at a value of 1850 parr/km on the CDF.
Evaluation Thresholds
Pass – The number of additional/new miles of high quality miles habitat (as determined by
ODFW’s Habitat Limiting Factors Model) equals or exceeds the threshold.
Fail – The number of additional/new miles of high quality miles habitat (as determined by
ODFW’s Habitat Limiting Factors Model) is less than the threshold.
Miles of high quality habitat needed to achieve delisting and broad sense recovery abundance
goals for coho.
Miles of High Quality Habitat
Population
Youngs Bay
Delisting
Broad Sense
1.5
137
Big Creek
11.4
87.4
Clatskanie
19
19
Scappoose
10
24
Clackamas
27.1
88.1
Sandy
41.5
41.5
Lower Gorge
10
31
Upper Gorge/Hood
53
54
References
Anlauf, K., K. Jones, C. Stein, and P. Kavanagh. 2006. Lower Columbia River Basin Coho Salmon
Habitat Assessment: Status of Habitat and Production Potential and Capacity for Coho Salmon.
Oregon Department of Fish and Wildlife, Salem, Oregon.
Firman, J.C., and S.E. Jacobs. 2001. A survey design for integrated monitoring of salmonids. In Nishida,
T., P. J. Kailola and C. E. Hollingworth editors. First International Symposium on GIS in Fishery
Science.
Lawson, P.W., E.P. Bjorkstedt, M.W. Chilcote, C.W. Huntington, J.S. Mills, K.M.S. Moore, T.E.
Nickelson, G.H. Reeves, H.A. Stout, T.C. Wainwright, and L.A. Weitkamp. 2007. Identification
of historical populations of Coho salmon (Oncorhynchus kisutch) in the Oregon coast
evolutionarily significant unit. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-79.
Oregon Coastal Restoration Initiative (OCSRI). 1997. The Oregon Plan: Oregon's Coastal Restoration
Initiative. Salem, Oregon.
Oregon Department of Fish and Wildlife. 2007. State of Oregon Conservation Plan for the Oregon Coast
Coho Evolutionarily Significant Unit, Appendix 2. Oregon Department of Fish and Wildlife,
Salem, Oregon.
Rodgers, J.D., K.K. Jones, A.G. Talabere, C.H. Stein, and E.H. Gilbert. 2005. Oregon Coast Coho
Habitat Assessment, 1998-2003. OPSW-ODFW-2005-5, Oregon Department of Fish and
Wildlife, Salem.
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.
Thom, B. A., K. K. Jones, and C. S. Stein. 1998. An analysis of historic, current, and desired conditions
for streams in western Oregon. Section IV-ODFW pages 33-56 In The Oregon Plan for Salmon
and Watersheds 1998 Annual Report. (http://www.oregon-plan.org)
Wainwright, T. C., M. W. Chilcote, P. W. Lawson, T. Nickelson, C. W. Huntington, J. S. Mills, K. M. S.
Moore, G. H. Reeves, H. A. Stout, and L. A. Weitkamp. 2006. Biological recovery criteria for the
Oregon Coast coho salmon evolutionarily significant unit. Draft Report, January 2006.
(Available from T. C. Wainwright, NWFSC, Fish Ecology Division, Newport Research Station,
Newport, OR.)