Prepared in cooperation with The Nature Conservancy and the Bureau of Reclamation

Distribution and Condition of Young-of-Year 

Lost River and Shortnose Suckers in the 

Williamson River Delta Restoration Project and 

Upper Klamath Lake, Oregon, 2008–10—Final Report

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2012–1098

Distribution and Condition of Young-of-Year Lost River 

and Shortnose Suckers in the Williamson River Delta 

Restoration Project and Upper Klamath Lake, Oregon, 

2008–10—Final Report

By Summer M. Burdick and David A. Hewitt 

Prepared in cooperation with The Nature Conservancy and 

the Bureau of Reclamation

Open-File Report 2012-1098

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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Suggested citation: 

Burdick, S.M, and Hewitt, D.A., 2012, Distribution and condition of young-of-year Lost River and shortnose suckers 

in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon, 2008–10—Final Report: U.S. 

Geological Survey Open-file Report 2012-1098, 52 p. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted material contained within this report.
iii

Contents

Executive Summary....................................................................................................................................................... 1

Introduction and Background......................................................................................................................................... 2

Description of Study Area .............................................................................................................................................. 5

Larval Fish Collection .................................................................................................................................................... 6

Juvenile Fish Collection................................................................................................................................................. 7

Recolonization of the Williamson River Delta by Juvenile and Small Adult Fishes ........................................................ 8

Description of the Fish Assemblage and Evaluation of the Risk of Predation to Endangered Suckers.......................... 9

Geographic and Temporal Use of the Restored Williamson River Delta by Larval and Juvenile Suckers ................... 10

Larval Sucker Distribution Among Habitats.............................................................................................................. 10

Temporal Use of the Williamson River Delta by Larval Suckers .............................................................................. 11

Timing and Distribution of Age-0 Juvenile Sucker Catches...................................................................................... 12

Timing and Distribution of Age-1 and Older Juvenile Sucker Catches ..................................................................... 12

Quantitative Comparisons of Habitat Use by Age-0 Juvenile Suckers......................................................................... 13

Quantitative Estimation of Sucker Habitat Use......................................................................................................... 13

Quantitative Estimates of the Portion of Habitat Used by Age-0 Suckers ................................................................ 14

Quantitative Estimation of Habitat Use by Low and High Abundances of Age-0 Suckers........................................ 15

Quantitative Estimates of Habitat Use by Abundance Classes of Age-0 Suckers.................................................... 15

Condition and Health of Juvenile Suckers ................................................................................................................... 16

Summary ..................................................................................................................................................................... 18

Acknowledgments........................................................................................................................................................ 18

References Cited......................................................................................................................................................... 19

Appendix - List of Products.......................................................................................................................................... 49
iv

Figures

Figure 1. Geographic location of the Williamson River Delta Preserve Restoration Project in relation to other 

aquatic environments and state boundaries ............................................................................................................ 25

Figure 2. Habitats sampled in and adjacent to the Williamson River Delta, Oregon ............................................... 26

Figure 3. Locations of nine sampling areas and sites sampled with trap nets during summer 2010 in Upper 

Klamath Lake, Agency Lake, and the Williamson River Delta Preserve, Oregon .................................................... 27

Figure 4. Schematic boxplots of standard length of yellow perch and age-0 juvenile suckers, captured in the 

Williamson River Delta, Oregon, and adjacent lake habitats, 2008–10.................................................................... 28

Figure 5. Locations where larval Lost River suckers and larvae identified as either shortnose or 

Klamath largescale suckers were captured in Agency Lake, Upper Klamath Lake, and the Williamson 

River Delta Preserve, Oregon, 2008–09.................................................................................................................. 29

Figure 6. Number of larval Lost River and shortnose or Klamath largescale suckers caught per cubic 

meter of water filtered, by week in 2008 and 2009, in two habitats in the Williamson River Delta Preserve 

(Tulana Emergent and Tulana Open Water), in Upper Klamath Lake, and in Agency Lake, Oregon ...................... 30

Figure 7. Locations that age-0 and age-1 Lost River suckers and shortnose suckers were captured 

in trap-net sampling in the Williamson River Delta, Oregon, and adjacent lake habitats, 2008–10 ......................... 31

Figure 8. Schematic boxplots showing timing of age-0 sucker catches in trap nets set in four habitats in the 

Williamson River Delta Preserve and in northern Upper Klamath Lake, and in southern Agency Lake, 

Oregon, 2008–10..................................................................................................................................................... 32

Figure 9. Schematic boxplots showing timing of age-1 sucker catches in trap nets set in four habitats

in the Williamson River Delta Preserve and in northern Upper Klamath Lake, and in southern Agency 

Lake, Oregon, 2008–10........................................................................................................................................... 33

Figure 10. Estimated portion of habitat used by age-0 juvenile suckers in the Williamson River Delta 

Preserve and two adjacent lake habitats, Oregon, over time in 2008 ...................................................................... 34

Figure 11. Estimated portion of habitat used by age-0 juvenile suckers in the Williamson River Delta 

Preserve and two adjacent lake habitats, Oregon, over time in 2009 ...................................................................... 35

Figure 12. Estimated probability that a sample site in Upper Klamath Lake, Agency Lake, or the 

Williamson River Delta, Oregon, was used in 2010 by more than five age-0 suckers at a given depth................... 36

Figure 13. Schematic box plots showing age-0 Lost River and shortnose sucker weight in 

10 mm length bins, captured in Agency Lake, Upper Klamath Lake, and the Williamson River Delta, 

Oregon, 2008–10..................................................................................................................................................... 37
v

Tables

Table 1. Number of fish species, excluding endangered suckers, captured in trap nets each year in 

six habitats sampled in and adjacent to the Williamson River Delta, Oregon .......................................................... 38

Table 2. Characteristics of fishes, excluding endangered suckers, captured in and adjacent to the 

Williamson River Delta, Oregon............................................................................................................................... 39

Table 3. Ratio of the number of juvenile or small adult fish that potentially prey on larval suckers to those 

that do not prey on larval suckers, captured in and adjacent to the Williamson River Delta, Oregon, 2008–10 ...... 40

Table 4. Ratio of the number of juvenile or small adult fish that potentially prey on age-0 juvenile suckers to

those that do not prey on age-0 juvenile suckers, captured in and adjacent to the Williamson River Delta, 

Oregon, 2008–10..................................................................................................................................................... 40

Table 5. Ratio of the number of native fish to non-native fish, captured in and adjacent to the Williamson River 

Delta, Oregon, 2008–10 .......................................................................................................................................... 40

Table 6. Percentage of nets set in and adjacent to the Williamson River Delta that captured Lost River 

sucker larvae and larvae identified as either shortnose or Klamath largescale sucker, 2008–09 ............................ 41

Table 7. Ratio of larvae identified as Lost River suckers to those identified as either shortnose or Klamath 

largescale suckers collected in four sampling areas in and adjacent to the Williamson River Delta, 2008–09........ 41

Table 8. Ratio of age-0 juvenile Lost River suckers to shortnose suckers collected in six sampling areas in 

and adjacent to the Williamson River Delta, Oregon, 2008–10................................................................................ 41

Table 9. Number of age-0 suckers caught per net set in each of six areas in and adjacent to the Williamson 

River Delta, Oregon, 2008–10 ................................................................................................................................. 42

Table 10. Number of age-1 suckers caught per net set in each of six areas in and adjacent to the Williamson 

River Delta, Oregon, 2008–10 ................................................................................................................................. 42

Table 11. Models fit to age-0 sucker habitat use data collected the Williamson River Delta, Oregon, and 

adjacent lake habitats, 2008 .................................................................................................................................... 43

Table 12. Models fit to age-0 sucker habitat use data collected the Williamson River Delta, Oregon, and 

adjacent lake habitats, 2009 .................................................................................................................................... 44

Table 13. Explanatory habitat use models fit to age-0 sucker categorical abundance data collected from 

the Williamson River Delta, Oregon, and adjacent habitats, 2010 ........................................................................... 45

Table 14. The confidence set of models fit to age-0 sucker categorical abundance data collected in the 

Williamson River Delta, southern Agency Lake, and northern Upper Klamath Lake, Oregon, 2010........................ 46

Table 15. Estimated portion of habitats used each week in 2010 by at least one age-0 sucker (ψlow) .................... 47

Table 16. Estimated portion of habitats used each week in 2010 by more than five age-0 suckers (ψhigh) ............. 48

Table 17. Percentage of juvenile suckers collected from Upper Klamath Lake, Agency Lake, and the 

Williamson River Delta, Oregon, 2008–10 to have one or more deformed opercula in each year........................... 48
vi

Conversion Factors, Datums, and Abbreviations and Acronyms

Conversion Factors

Multiply By To obtain

Length

millimeter (mm) 0.03937 inch (in)

meter (m) 3.281 feet (ft) 

kilometer (km) 0.6214 mile (mi)

Speed

meters per second (m/s) 2.23 miles per hour (mph)

meters per second (m/s) 3.28 feet per second (fps)

Area

hectares (ha) 2.471 acres (ac)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32.

Datums

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Vertical datum is referenced to the BOR datum (NAVD 88-2.17ft.)

Abbreviations and Acronyms

Abbreviations Meaning

DO dissolved oxygen

LRS Lost River sucker

NL notochord length

OSU Oregon State University

pH potential hydrogen

SD standard deviation 

SNS shortnose sucker

SNS-KLS shortnose or Klamath largescale sucker

TNC The Nature Conservancy

USGS U.S. Geological Survey
1

Distribution and Condition of Young-of-Year Lost 

River and Shortnose Suckers in the Williamson River 

Delta Restoration Project and Upper Klamath Lake, 

Oregon, 2008–10—Final Report

By Summer M. Burdick and David A. Hewitt

Executive Summary

The Nature Conservancy undertook restoration of the Williamson River Delta Preserve 

with a primary goal "to restore and maintain the diversity of habitats that are essential to the 

endangered [Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes 

brevirostris)] while, at the same time, minimizing disturbance and adverse impacts" (David 

Evans and Associates, 2005). The Western Fisheries Research Center of the U.S. Geological 

Survey was asked by the Bureau of Reclamation to assist The Nature Conservancy in assessing 

the use of the restoration by larval and juvenile suckers. We identified five obtainable objectives 

to gauge the habitat suitability for young-of-year suckers in the permanently flooded portions of 

the two most recently restored sections (Goose Bay and Tulana) of the Williamson River Delta 

Preserve (hereafter referred to as the Preserve) and its effects on the distribution and health of 

larval and juvenile suckers. Several of these objectives were met through collaborations with The 

Nature Conservancy, Oregon State University, Oregon Water Science Center, and Leetown 

Science Center. 

Our findings were in concurrence with those of The Nature Conservancy, who found that 

the Preserve supported young-of-year suckers at least as well as adjacent lake habitats (Erdman 

and others, 2011) despite the prevalence of non-native and piscivorous species in the system. The 

Preserve was recolonized by all fishes in the regional species pool, both native and non-native,

between the time each portion of the Preserve (Goose Bay and Tulana) was inundated in autumn

and the following spring. A large number of fish capable of preying on endangered larval suckers

and a few fish that could prey on juvenile suckers were captured in the Preserve, but these 

species were no more abundant in the Preserve than in adjacent lakes.

Larvae and age-0, age-1, and age-2 juvenile Lost River and shortnose suckers were 

captured in the Preserve, Upper Klamath Lake, and Agency Lake, indicating that these species 

reared in restored and unaltered lake habitats. We captured too few larval suckers to examine 

patterns in spatial or temporal distribution. Once endangered suckers transitioned into juveniles, 

as defined by morphological development, they continued to disperse from shallow to deep water 

throughout the Preserve and into adjacent lakes. Age-1 and age-2 suckers captured throughout 

the Preserve and in adjacent lake habitats, especially in spring, show continued use of restored 

habitat by these species.
2

Quantitative examination of habitat use by age-0 juvenile suckers that accounted for 

imperfect detection indicated the portion of habitat used increased throughout July and August 

each year until the entire study area was used by one or more age-0 juvenile suckers by the end 

of August. Our rigorous evaluation showed both restored Preserve and unaltered lake habitats 

were equally used by age-0 juvenile suckers. Although all sampled habitats were used, multistate occupancy models indicated that more age-0 suckers occupied shallow rather than deep 

habitats within the range of depths we sampled (0.5–4.3 m). 

We were unable to compare health and condition of juvenile suckers among habitats, due 

to their movement among habitats. However, documentation of length-weight relationships,

afflictions and deformities, and histology indicated juvenile suckers captured in all habitats 

maintained a similar level of health among the 3 years of our study.

Introduction and Background

Lost River sucker (Deltistes luxatus; LRS) and shortnose sucker (Chasmistes brevirostris;

SNS) were listed as federally endangered in 1988 following apparent decreases in adult 

abundance (U.S. Fish and Wildlife Service, 1988). Although once abundant throughout their 

range, sucker populations were extirpated from Lower Klamath Lake, Sheepy Lake, and Lake of 

the Woods, and it is suspected that populations in Tule Lake and Keno Reservoir no longer 

reproduce (National Research Council, 2004). The primary threat to Lost River and shortnose 

sucker persistence is a lack of recruitment to the adult spawning populations (Janney and others, 

2008; Hewitt and others, 2011), the cause of which is currently unknown, but could be attributed 

to poor water quality, avian predation, lack of suitable habitat, algal toxins, or some other factor.

The Williamson and Sprague Rivers provide one of two spawning habitats for LRS and 

SNS residing in Upper Klamath Lake, the other being lakeshore spring sites along the eastern 

boundary of the lake (National Research Council, 2004). Spawning for both species typically 

occurs between March and May (Ellsworth and others, 2009). Eggs are spread over gravel and 

cobble substrates (Andreasen, 1975). Between mid-April and late May, larvae spawned in the 

river systems emerge from gravel and drift downstream (Ellsworth and others, 2009). Larvae 

begin to reach the Preserve by late April (Crandall and others, 2008; Ellsworth and others, 2009). 

By mid-July, most young-of-year suckers have developed into juveniles (Kelso and Rutherford, 

1996; U.S. Geological Survey, unpub. data, 2010). Between June and September, age-0 larval 

and juvenile suckers disperse throughout Upper Klamath Lake and its littoral marshes (Burdick 

and others, 2009b). Population demography, distribution, and habitat use during the transition 

from juvenile to adult life stages (a period of time between 5 and 7 years) is poorly understood

(Burdick and others, 2009b). 
3

Wind-driven water currents in Upper Klamath Lake typically flow in a clockwise 

direction and may push larvae originating from the Williamson and Sprague Rivers south along 

the eastern shore to the lake outlet and into Keno Reservoir (fig. 1). It is suspected that larvae 

entering Keno Reservoir are lost to the population due to poor survival and an inability to return 

to natal spawning locations (Markle and others, 2009). Markle and others (2009) estimate that 

prior to the restoration of the Preserve it took an average of 5 days for LRS and 10 days for SNS

to be transported from the mouth of the Williamson River out of Upper Klamath Lake. The 

difference in transport time appears to be a function of when and where larvae drift in relation to

the major lake currents (Markle and others, 2009). One hypothesized method for slowing the 

transport of larvae from the lake is to create well-vegetated marshes that allow fish to escape the 

main current (Markle and others, 2009).

Poor survivorship between juvenile and adult life stages is one of several reasons cited 

for the decrease and lack of recovery of LRS and SNS (National Research Council, 2004). Sharp 

decreases in age-0 catch rates during August and early September and extremely low catches of 

age-1 suckers indicate juvenile survival is the primary factor limiting recruitment into adult 

spawning populations (Simon and Markle, 2002; Hendrixson and others, 2007; Burdick and 

Brown, 2010). Poor juvenile survival may result from increased predation due to inadequate 

shelter from predators, any number of physiological stressors (for example, disease, toxins, or 

water quality), or some heretofore unrecognized age-class specific factor, all of which may be 

exacerbated by a lack of high quality rearing habitat.

Historically, larval and juvenile suckers had access to habitat in vast wetlands along the 

northern parts of Upper Klamath Lake and in the Preserve, which may have functioned as 

nurseries. Extensive diking and draining of wetlands for agriculture between 1915 and 1995 

eliminated an estimated 66 percent of wetlands adjacent to Upper Klamath (Larson and Brush, 

2010). Recent research indicates that age-0 juveniles use various habitats throughout Upper 

Klamath Lake, including stands of emergent vegetation in and around the Preserve (Burdick and 

others, 2009a). Age-1 suckers are concentrated near patches of vegetation in tributary mouths 

and springs during April and May (Markle and Simon, 1993; Burdick and Brown, 2010) and are 

found throughout Upper Klamath Lake in June and July (Bottcher and Burdick, 2010).

The Preserve likely was an important wetland for larval and juvenile suckers, due to its 

location downstream of known productive spawning grounds in the Williamson and Sprague 

Rivers (fig. 1) (National Research Council, 2004). Established wetlands composed of emergent 

macrophytes, similar to what probably historically existed in the Preserve, support more, larger, 

and better-fed larvae than habitats characterized as having submergent macrophytes, woody 

vegetation, or open water (Cooperman and Markle, 2004). More recently, larval suckers were

documented in Riverbend and South Marsh, two pilot restoration wetlands at the Preserve, and in 

Tulana and Goose Bay (fig. 2) (Crandall and others, 2008; Hendrixson, 2008; Erdman and 

others, 2011). Historically, juvenile suckers may have reared for several months to several years 

in the emergent or submerged vegetation and deep water wetlands along marsh edges or in the 

marsh interior (National Research Council, 2004). Without the availability of the Preserve, larval 

suckers originating in the Williamson and Sprague Rivers could out-migrate into Upper Klamath 

Lake as rapidly as 1 day, often before caudal fin development occurs. Such rapid migration could 

reduce swimming performance and foraging success of larval suckers (Cooperman and Markle, 

2000; 2003). 
4

The Nature Conservancy (TNC) began restoring the Williamson River Delta in 1999, 

because this area is essential to the survival of the endangered suckers (David Evans and 

Associates, 2005). Restoration activities include breaching levees along Agency Lake and Upper 

Klamath Lake shorelines, filling toe drains, excavating and reconnecting an historical oxbow, 

creating an additional channel at the Williamson River mouth, creating a riparian bench and 

breaching levees along the Williamson River, and managing vegetation (David Evans and 

Associates, 2005). Hydrologic connectivity was achieved for more than 1,000 ha to the 

northwest of the Williamson River (Tulana) in October 2007 and an additional 1,000 or more ha

to the southeast of the river in November 2008 (Goose Bay) (Erdman and others, 2011).

Prior to restoration, larval sucker monitoring occurred in the Williamson and Sprague 

Rivers (Ellsworth and others, 2009), Upper Klamath Lake (Simon and others, 2009), Riverbend 

and South Marsh restoration sites, and the shoreline of Goose Bay (Crandall and others, 2008; 

Erdman and others, 2011). In addition, juvenile sucker monitoring occurred throughout Upper 

Klamath Lake (Burdick and others, 2009b), and along the shore of Agency Lake (Simon and 

others, 2009). The U.S. Geological Survey (USGS) began work under contract with the Bureau 

of Reclamation (Interagency Agreement 07AA200135) to assist TNC in assessing the success of 

the delta restoration in providing high quality habitat for larval and juvenile fish in the 

permanently flooded areas of the project. The Nature Conservancy expanded their larval 

sampling program into the newly restored Tulana and Goose Bay areas of the Preserve (Erdman 

and Hendrixson, 2010; Erdman and others, 2011), and Oregon State University (OSU) adjusted 

their shoreline sampling to include the new contours of the lake shore (Simon and others, 2009). 

U.S. Geological Survey larval sampling differed from TNC’s in the depth sampled and gear 

used, but our objectives with regard to understanding larval sucker use of restored habitat were 

similar. Collaboration between TNC, OSU, and USGS's Oregon Water Science and Western 

Fisheries Research Centers also was formed in 2008 to evaluate the effects of hydraulics and 

larval sucker behavior on larval distribution and retention in the Preserve (T. Wood, U.S. 

Geological Survey, written commun., 2011; Wood and others, 2011).

The specific objectives addressed in this report are: 

• Objective 1: Describe geographic and temporal use of permanently flooded environments in 

the Preserve by larval and juvenile suckers. 

• Objective 2: Compare the probability of habitat use by juvenile suckers among habitats in 

the Preserve and open-water areas of Upper Klamath and Agency Lakes. 

• Objective 3: Compare fish species composition, with special attention to non-native and 

piscivorous fishes, in the Preserve, Upper Klamath Lake, and Agency Lake. 

• Objective 4: Describe the temporal and spatial colonization of environments within the 

Preserve by juvenile suckers and other fish species. 

• Objective 5: Compare the growth, condition, and health of juvenile suckers from the 

Preserve to those from Upper Klamath and Agency Lakes.

The rationale for each objective, methods used, and results are discussed below. A 

complete list of products produced with assistance from funding secured under Interagency 

Agreement 07AA200135 is given in appendix A.
5

Description of Study Area 

The study area is located in south-central Oregon and includes the parts of the Preserve

that were most recently restored (Tulana and Goose Bay), a southern part of Agency Lake, and a 

northern part of Upper Klamath Lake (fig. 1). The Williamson River is the largest tributary of 

Upper Klamath Lake. It flows approximately 85 km from its headwaters in Klamath Marsh and 

has one major tributary, the Sprague River. The Preserve connects Agency and Upper Klamath 

Lakes and is divided in two by the Williamson River: (1) Goose Bay to the south and east and 

(2) Tulana to the west and north (fig. 2). The lakes and permanently flooded wetland areas in 

Tulana are hypereutrophic and experience massive seasonal blooms of the cyanobacterium

Aphanizomenon flos-aquae. These blooms are associated with dissolved oxygen (DO) 

concentrations that fluctuate between supersaturation and anoxia and pH levels that frequently 

exceed 9.0 (Lindenberg and others, 2008; Wong and others, 2010). High pH and low DO 

concentrations occur every summer at levels potentially lethal to juvenile LRS and SNS in Upper 

Klamath Lake and in the Preserve. High un-ionized ammonia concentrations also occasionally 

occur in Upper Klamath Lake (Wood and others, 2006).

There are six distinct habitats in the study area, based on the combination of location and 

type of plant community—three are located in Tulana, one in Goose Bay, one in southern 

Agency Lake , and one in northern Upper Klamath Lake (figs. 1 and 2). The Nature Conservancy 

defined wetland habitats in Tulana and Goose Bay based on the predicted response of broadscale plant community types to hydrologic reconnection with the lakes and river following 

restoration (David Evans and Associates, 2005). Tulana habitats include: (1) the western part of 

Tulana predicted to remain unvegetated (Tulana Open Water), (2) an area located in the center of 

Tulana predicted to establish submergent vegetation (Tulana Submergent), and (3) the eastern 

side of Tulana predicted to establish emergent vegetation (Tulana Emergent; fig. 2). Tulana 

Submergent in our report is referred to as deep water wetland by TNC. The Agency Lake habitat 

includes a narrow waterway connecting Agency and Upper Klamath Lakes known as Agency 

Strait.

There is substantial variation in water depth and the abundance of aquatic vegetation, but

very little variation in substrate composition among habitats. Substrate in the Preserve consists 

primarily of mud and clay (Lather muck and Tulana silt loam; David Evans and Associates, 

2005), but substrates composed of sand mixed with gravel and cobble exist along the levy 

breaches. Agency and Upper Klamath Lakes are shallow (about 2–3 m) and mostly devoid of 

vegetation except along the shoreline. Agency Strait had a maximum depth of 7.4 m. Goose Bay 

has a maximum depth of about 1.2 m, but large portions of this area can be as shallow as 0.1 m 

or be completely dry by the end of September. This area is vegetated with patches of submergent 

and emergent vegetation (Elseroad and others, 2009). Tulana Open Water is the deepest and least 

vegetated of the areas in Tulana. Intermediate depths were found in Tulana Submergent (about 

1.50–2.75 m deep during our sampling season), which was vegetated with scattered patches of 

submergent vegetation. Tulana Emergent was the shallowest area sampled in Tulana (< 1 m) and 

vegetation in this area was nearly all emergent macrophytes interspersed between patches of 

open water. On the eastern edge of Tulana Emergent, some riparian vegetation also occurred 

(Elseroad and others, 2009).
6

Larval Fish Collection

Larval fish distribution at a coarse habitat scale was assessed with plankton nets and 

random stratified sampling. Random sampling complemented fixed-site sampling that was 

designed to assess larval fish distribution along hydrologic pathways (T. Wood, U.S. Geological 

Survey, written commun., 2011). We randomly selected sites from three Tulana habitats, Upper 

Klamath Lake, and Agency Lake in 2008 and 2009 (fig. 2). We collected 1–3 samples at 8–12 

randomly selected sites weekly between the beginning of May and early July in each of these 

years. Effort was equally divided among these habitats. 

Plankton nets were used to collect larvae from the top of the water column. These nets 

had 0.3-m-diameter mouth openings, a 2.5-m-long tail, 800-μm-mesh Nitex netting, and a 

removable cod end. A General OceanicsTM model 2030R mechanical flow meter was mounted in 

the mouth of each net so that the volume sampled could be calculated. The net was towed 

parallel to a boat at approximately 1 m/s for 3–5 minutes or until algae began to clog the mesh. 

After retrieval, all material was removed from nets and samples were immediately preserved in 

70–95 percent ethanol. We also recorded water temperature, water depth, and the portion of the 

sampled area covered by vegetation. 

We collected three sequential tows at a subset of 18 percent of sites in 2008, 19 percent 

of sites in 2009, and at all sites in 2010 to assess sampling efficiency and the variability in catch 

rates. These replicate tows were all started at the site origin, but the direction of the tow varied 

slightly so that the same volume of water was not sampled in each replicate. Larval sucker catch 

rates were highly variable among replicates, indicating larvae are not uniformly distributed. 

Sample densities did not decrease in sequential larval samples, indicating replicate net tows did 

not deplete larvae at each site. Sample variability is described in detail in Burdick and others 

(2009a), Burdick and Brown (2010), and Burdick (2012). 

In the laboratory, fish were identified to species or lowest taxonomic unit practical. 

Larval fish were identified based on gut length, body shape, and pigmentation (Remple and 

Markle, 2005; D. Simon, Oregon State University, written commun., 2004). Using this method, 

larval suckers were identified as Lost River suckers, or a group of either shortnose or Klamath 

largescale suckers (SNS-KLS). Sculpin (Cottus spp.) were identified to genus due to the lack of a 

suitable larval identification key for these species. The notochord lengths (NL) of the first 10 

larvae of each non-sucker species and all larval suckers were measured and all larval fish were 

enumerated. Notochord and standard length are the same for larval suckers; therefore, this 

measurement is comparable to those reported by TNC and OSU. Larval density for each species 

was calculated by dividing the total number of fish in each sample by the volume of water 

filtered. 
7

Juvenile Fish Collection

We used trap nets and a random stratified sampling approach to compare juvenile fish 

distribution and condition among habitats in the Preserve, northern Upper Klamath Lake, and 

southern Agency Lake. Trap nets were rectangular with mouth dimensions of 0.61 × 0.91 m, a 

10-m-lead, and three internal fykes. Nets were set overnight for a target soak time of about 20 

hours and water depth was recorded at each net site. In 2008, sites were randomly chosen from 

three habitats in Tulana, and one each in southern Agency Lake and northern Upper Klamath 

Lake (fig. 2). Sample sites were added in Goose Bay in 2009 after this area was flooded in fall 

2008. In 2010, a reduced budget forced us to alternate weeks in which Agency and Upper 

Klamath Lakes were sampled. We also refined our habitat stratification in northern Upper 

Klamath Lake and southern Agency Lake in 2010 by redefining these areas in terms of four 

habitats: Fish Banks, Mid-North, Agency Strait, and Agency Near Shore (fig. 3). Sample 

allocation was initially distributed equally among habitats within each year, but as the shallowest 

habitats became inaccessible due to declining lake-surface elevation, effort was reallocated to 

deep areas. Low lake-surface elevations prevented us from sampling in the shallow Goose Bay 

or Tulana Emergent habitats after July 23, 2008, August 25, 2009, and July 19, 2010.

Lake habitats were defined based on a combination of location, depth, and nearness to 

vegetation. Fish Banks was less than 1.5-m-deep and vegetated with emergent macrophytes. 

Mid-North and southern Agency Lake habitats were approximately 1 to 2.5-m deep and mostly 

unvegetated. Water depth in Agency Strait was up to 5 m deep, but due to the narrow shape of 

this habitat unit no site within it was more than 20 m from emergent vegetation. Overall, water 

depth at our sample sites ranged from 0.5 to 4.3 m, and 96 percent of samples were collected in 

water less than 4 m deep.

Data collection within a subset of sampling weeks each year was designed to meet the 

requirements for occupancy analyses that allow for quantitative estimation of detection and

habitat-use probabilities for rare species, such as suckers. Repeat samples, which may occur over 

space or time, are necessary to estimate the probability of habitat use when detection is imperfect 

or variable. Repeat sampling was conducted between June 23 and July 28 in 2008, June 30 and 

August 31 in 2009, and August 2 and September 13, 2010. 

Our strategy for obtaining repeat samples for use in occupancy models changed between 

the 2009 and 2010 field seasons, following initial data analysis and reevaluation of our methods. 

We obtained repeat samples at sites by setting multiple trap nets simultaneously in 2008 and 

2009, allowing us to estimate changes in habitat use as a function of time. Evaluation of this 

technique in 2009 revealed that use of trap nets and spatial replication may lead to a negative 

bias in habitat use, especially at times of the year when the abundance of juvenile suckers is low 

(Burdick and Hewitt, U.S. Geological Survey, unpub. data, 2009). Therefore, in 2010 we 

redesigned our sampling such that repeat samples were obtained by setting a single trap net at a

site three times within a week. Replicate samples were collected at a large number of sites on one 

occasion in 2008 and one occasion in 2009, whereas replicate samples were collected at a small 

number of sites every 2 weeks in 2010. Our 2010 sampling reduced bias in estimates of habitat 

use and still allowed for evaluation of habitat use over time, albeit over a 2 week rather than a 1 

week period. 
8

We recorded the condition and standard length (SL) of all suckers, and length and 

abundance data were collected on non-target species from all nets set in 2008 and 2009, and 

about 10 percent of nets set in 2010. Parasites, deformities, emaciation, red marks, or unusual 

appearances were noted. Approximately one-third of all suckers shorter than 70 mm SL, and

one-tenth of all suckers 70–140 mm SL were sacrificed and preserved in 95-percent denatured 

ethanol for later identification and a concurrent histology study. Suckers were sacrificed 

throughout the week in 2008 and 2009, but were only sacrificed on the last day of sampling each 

week in 2010. In the laboratory, we weighed each sacrificed sucker and identified juvenile 

suckers to the species level following Markle and others (2005) using a combination of 

techniques that included vertebrae enumeration, lip morphology, and gill-raker counts. We 

classified suckers as age-0, age-1, or older based on weekly length frequency plots. Otoliths and 

fin rays were examined from approximately 10 suckers collected in 2008 and 2009 to confirm 

age classification. 

Catch per unit effort for each species and age class was calculated as fish per net rather 

than fish per hour because there was no evidence of a relation between the number of hours nets 

soaked and the number of fish captured. To estimate the number of suckers of each species, the 

composition of sacrificed suckers from each habitat and week was applied to the unsacrificed 

portion of suckers caught in each net. 

Recolonization of the Williamson River Delta by Juvenile and Small Adult 

Fishes

Understanding the recolonization process in the Preserve will help in developing 

expectations for future wetland restoration projects in and around Upper Klamath Lake, and may 

help to identify potential interactions among species. Wetlands can recover a maximum number 

of species after years of desiccation in as little as a few months (Paller, 1997; Baber and others,

2002), or as long as 5 years (Simenstad and Thom, 1996). We predicted the Preserve would be 

quickly recolonized by all fishes common to Upper Klamath and Agency Lakes, given 

connectivity to these habitats. 

In initial post-restoration trap-net sampling, species richness, unadjusted for detection 

probability, was similar in restored habitats and adjacent lakes (table 1). Furthermore, richness in 

restored habitats did not change substantially in subsequent sampling, indicating recolonization 

by all species occurred within 6–7 months after flooding the Preserve. Of the 14 species detected 

throughout the study area, at least 10 were detected in every habitat every year: largemouth bass

(Micropterus salmoides), Klamath redband trout (Oncorhynchus mykiss newberrii), slender 

sculpin (Cottus tenuis), and Klamath speckled dace (Rhinichthys osculus klamathensis) were not 

detected in all habitats. Absences of these species from our sampling in some habitats and in 

some years probably is due to a low probability of detection and should not be interpreted as true 

absence from habitats. Rapid recolonization of restored habitats is probably the result of the 

location of the Preserve relative to source populations, the high level of connectivity between the

Preserve and source populations, and suitability of restored habitats for these fishes. 
9

Description of the Fish Assemblage and Evaluation of the Risk of 

Predation to Endangered Suckers 

We used species composition to describe habitat use by juvenile and small adult fishes in 

the study area and the risk of predation to larval and juvenile suckers. The number and relative 

abundance of native and non-native fish species were used to describe fish assemblages. We 

summarize catches and distribution of piscivorous fishes, because a large number of these 

species have the potential to reduce the overall benefits of the restoration to suckers, especially if 

they co-occur with suckers small enough to be preyed upon. A fish species is considered to be a 

potential larval sucker predator if it is known to eat larval fish and a potential juvenile sucker 

predator if it is known to eat fish of similar size to the juvenile suckers captured in this study. 

Diets were determined based on a literature review and not directly verified. We assumed that 

Klamath tui chub (Siphatales bicolor bicolor) eat larval fish based on the finding by Bond and 

others (1968) and that blue chub (Gila coerulea) collected concurrently in Upper Klamath Lake 

ate larval fish and appeared to have similar diets to Klamath tui chub. This assumption is also 

loosely supported by an observation by Koch (1973) that tui chub eat cui-ui sucker (Chasmistes 

cujus) eggs in the Truckee River. Although we believe it is reasonable to assume that tui chub 

prey on larval suckers, Klamath tui chub diets should be confirmed. The only species captured in 

this study for which there is specific documentation of predation on suckers is fathead minnow. 

Fathead minnow (Pimephales promelas) ate larval suckers in a laboratory study in which the 

larval suckers were the only prey item (Markle and Dunsmoor, 2007). The diets for each species 

are given in table 2.

The juvenile and small adult fish assemblage was similar in the Preserve, adjacent lakes, 

and in the Upper Klamath National Wildlife Refuge marsh (Mulligan and Mulligan, 2007),

indicating restored habitat was no more or less suitable than unaltered habitat. Five non-native 

and eight piscivorous fishes were captured. Potential larval sucker predators (table 2) far 

outnumbered non-predators in all habitats, but were proportionally more abundant in our samples 

in the Tulana Open Water and Tulana Submergent habitats in 2008 and 2009 and in the Tulana 

Emergent habitat in 2010 (table 3). Potential juvenile sucker predators were outnumbered by fish 

that could not prey on juvenile suckers in all habitats and in all years (table 4). Non-native fish 

outnumbered native fish in most habitats and years (table 5). Native fishes were more abundant 

than non-native fishes in Tulana Emergent and northern Upper Klamath Lake in 2008 and 2010, 

in southern Agency Lake in 2008, and in Goose Bay in 2010 (table 5). 

Based on their relative abundance and co-occurrence with larval suckers, non-native adult 

fathead minnow and native juvenile Klamath tui chub have the potential to consume more larval 

suckers than other predatory fishes. During the time period in which larval suckers were present 

each year, these two species made up 53 percent of trap-net catches in 2008, 90 percent in 2009, 

and 80 percent in 2010. Non-native yellow perch (Perca flavescens) and native blue chub also 

were present during these time periods but made up substantially smaller portions of the catch. 

Fathead minnows and Klamath tui chubs were at least as abundant in our trap-net catches in the 

habitats most used by larval suckers (Tulana Emergent and Goose Bay) as they were in other 

habitats during the time period that larval suckers were detected. Relatively large catches of 
10

fathead minnows in May and June occurred about as frequently in Tulana Emergent and Goose 

Bay as they did in all other habitats, with the exception of northern Upper Klamath Lake where 

large catches were less common. Klamath tui chub, on the other hand, were slightly more 

abundant in 2009 and 2010 May and June samples in the Tulana Emergent habitat than in other 

habitats. 

Yellow perch per trap net frequently numbered in the hundreds, but few were large 

enough to prey on juvenile suckers. Using the length- and gape-size limitations of yellow perch 

(Truemper and Lauer, 2005), we determined that 0.6 percent in 2008, 16 percent in 2009, and 4 

percent in 2010 could prey on the smallest age-1 suckers. Twenty-three percent of yellow perch 

in 2008 and 2009 and 10 percent in 2010 could prey on the smallest age-0 suckers concurrently 

present (fig. 4). Yellow perch large enough to prey on juvenile suckers were found in all habitats 

sampled and we did not detect a pattern in their relative abundance among habitats. 

Detection of the larvae of four piscivorous fishes—fathead minnow, yellow perch, blue 

chub, and tui chub—indicated that the areas sampled provided some rearing habitat for these 

species. Yellow perch larvae were rare in our trawls and in larval sampling conducted by TNC 

(Erdman and Hendrixson, 2010, 2011), indicating that this species primarily spawns outside of 

our study area or is difficult to detect until the juvenile life stage. Catches of the other three 

species were much more common throughout the study area, indicating these species rear in the 

Preserve and in the lakes. 

Geographic and Temporal Use of the Restored Williamson River Delta by 

Larval and Juvenile Suckers

Two primary goals of the Williamson River Delta restoration project are to retain and 

provide quality rearing habitat for larval Lost River and shortnose suckers. Retention of sucker 

larvae in wetland habitats may play a role in good year-class formation (Markle and others, 

2009) by providing high quality juvenile sucker rearing habitat that may in turn assist suckers in 

surviving to recruitment. We examined larval catch data to determine if larval suckers were 

retained in restored habitats in the Preserve. In addition, we compared catch data in both restored 

Preserve habitats and unaltered lake habitats to determine when and where juvenile suckers 

reared. 

Fewer than 25 larvae of either sucker taxa were captured within a single sampling season 

in any sampling area, with the exception of Lost River sucker larvae captured in Upper Klamath 

Lake near the mouth of the Williamson in 2008 (n=82) and SNS-KLS larvae captured in Tulana 

Emergent in 2009 (n= 84). Therefore, catch data had to be pooled across either space or time for 

comparisons to be made, and any conclusions drawn from these data are tentative.

Larval Sucker Distribution Among Habitats 

Both larval sucker taxa were most frequently detected in 2008 and 2009 random stratified 

sampling in the Tulana Emergent, compared to the Tulana Open Water, Upper Klamath Lake, or 

Agency Lake (table 6). Once flooded, Goose Bay became accessible to larval suckers and 

opened a new pathway for entry into Upper Klamath Lake. Larval-transport modeling indicated 

larvae are distributed with the aid of wind-driven water circulation and prevailing spring winds 

from the northwest pushed larval suckers into Goose Bay in 2009 (T. Wood, U.S. Geological 

Survey, written commun., 2011). We were unable to detect this pattern with our sampling in 

2008 and 2009 because we did not sample in Goose Bay (fig. 5). 
11

Lost River sucker larvae were captured at higher rates than SNS-KLS larvae in all 

habitats in 2008, whereas SNS-KLS larvae were captured at higher rates than Lost River larvae 

in all habitats except Tulana Open Water in 2009 where only Lost River suckers were captured 

(table 7; fig. 6). This pattern was inconsistent with the pattern in species dominance for larval 

drift sampled in the Williamson River; SNS-KLS were more prevalent than Lost River suckers in 

2008 and the opposite was true in 2009 (Ellsworth and others, 2011; Ellsworth and Martin, 

2012). Larval sucker catch rates in the Williamson River were approximately 100 times greater 

than catch rates in our study area, and are a better indication of species composition in each year. 

Not only were our catches sparse they were unevenly distributed. For example, 82 of 114 Lost 

River sucker larvae captured in 2008 were captured in a single sample.

Our inability to detect consistent patterns in species composition contrasts with TNC’s 

consistently higher SNS-KLS catches compared to LRS catches. Ratios of larval Lost River to 

SNS-KLS captured in TNC pop nets set in water less than approximately 1-m-deep in Tulana 

and Goose Bay were 0.22 in 2008, 0.10 in 2009, and 0.12 in 2010 (Erdman and Hendrixson, 

2010, 2011). The inferences that can be made from TNC catches may be more reliable, given 

that they captured 5 to 10 times more larvae over the same time period that we sampled. 

Differential habitat use by these two taxa as larvae probably is due to a combination of behavior 

(for example, rheotaxis or habitat selection) and drift timing relative to hydrodynamics (T. 

Wood, U.S. Geological Survey, written commun., 2011). Due to their apparent habitat 

preferences, SNS-KLS larvae might have benefited more than LRS larvae from restoration due 

to the increase in shallow vegetated habitat that is otherwise in relatively low abundance in 

Upper Klamath and Agency Lakes, but both species probably benefited somewhat from the 

restoration. 

Temporal Use of the Williamson River Delta by Larval Suckers 

Due to very low larval catch rates, our ability to assess the timing of larval sucker habitat 

use is extremely limited. Lost River suckers were captured in relatively high abundance in this 

study at the mouth of the Williamson River between May 22 and June 10, 2008, and SNS-KLS 

were captured in relatively high numbers between May 26 and May 31, 2009.

Studies conducted concurrently with this study indicated sucker larvae used Goose Bay 

beginning in May and Tulana Emergent beginning in early June (Burdick and others, 2009a;

Burdick and Brown, 2010; Erdman and Hendrixson, 2010, 2011; Burdick, 2012). Catches of 

larval suckers in fixed site plankton tows that were collected for the validation of larval transport 

models corroborated general timing observed in the study described in this report; a large pulse 

of Lost River sucker larvae were captured at the mouth of the Williamson River between May 20 

and May 27, 2008 (Burdick and others, 2009a), and relatively high numbers of SNS-KLS were 

captured in Tulana Emergent between May 18 and June 8, 2009 (Burdick and Brown, 2010). 

These data also indicated a relatively high concentration of SNS-KLS used Tulana Emergent 

between June 24 and June 30, 2008, despite the fact they were not detected in high abundance in 

the random stratified sampling described in this report (Burdick and others, 2009a). Finally, 

fixed-site plankton sampling indicated that both larval sucker taxa were detected in relatively

high abundance in Goose Bay in May and were detected in Tulana Emergent after a windreversal event in early June 2009 and 2010 (Burdick and Brown, 2010; Burdick, 2012). 

Relatively high catches of SNS-KLS larvae captured in pop nets set in shallow water (< 1 m)

primarily occurred in the first 2 weeks of June in 2009 and 2010 in both Tulana Emergent and 

Goose Bay (Erdman and Hendrixson, 2010, 2011). Because pop nets catch more large larval 
12

suckers (10–27 mm; Erdman and Hendrixson, 2011) than surface-oriented plankton trawls (10–

19 mm, captured in our study), peak concentrations of SNS-KLS larvae in Goose Bay in early to 

mid-June as witnessed by Erdman and Hendrixson (2010) and Erdman and others (2011) rather 

than throughout May, as we observed, may indicate fish were retained and grew in that habitat.

Timing and Distribution of Age-0 Juvenile Sucker Catches 

The spatial differentiation in habitat use between larval sucker taxa did not carry over 

into the juvenile life stage. Our age-0 sucker catches were composed of more shortnose than Lost 

River suckers in Tulana Open Water and Tulana Submergent habitats in all 3 years, and in Goose 

Bay in 2009 and 2010. Ratios of these species, however, varied among years in other habitats 

sampled (table 8). Age-0 suckers appeared to be ubiquitously distributed throughout the study 

area and catch rates did not show consistent differences among habitats (fig. 7; table 9).

Differential habitat use among species at the juvenile life stage likely is driven by a number of 

interacting factors, including different larval distributions and habitat preferences.

Throughout most of the study area, age-0 suckers primarily were captured in August and 

early September in 2008, 2009, and 2010 (fig. 8). Exceptions occurred in the shallow Tulana 

Emergent habitat where most age-0 suckers were captured in mid-July in 2008, in early August 

in 2009, and not at all in 2010. Another exception was in Goose Bay where age-0 suckers were 

only captured on July 19 in 2010. The initiation of catches each year depends on age-0 suckers 

reaching a size that can be retained by the mesh size of our nets, whereas the decrease in catches 

is due to mortality, emigration from sampling areas, or both. Small numbers of age-0 suckers in 

Goose Bay and no age-0 suckers in Tulana Emergent in 2010 indicate suckers did not recruit to 

our gear before these areas became too shallow to sample after July 19.

Timing and Distribution of Age-1 and Older Juvenile Sucker Catches 

The timing of age-1 sucker catches was similar among years within habitats, but catch 

rates for age-1 suckers were lower in 2010 than in the previous 2 years (table 10). Age-1 suckers 

primarily were captured between early May and early July in 2008, 2009, and 2010 (fig. 9). 

Catches of this age class occurred slightly earlier in the shallow Goose Bay and Tulana Emergent 

habitat when compared to the other four deeper habitats, an observation that may be confounded 

by our inability to effectively sample these shallow water habitats as lake-surface elevation 

declined each year (Burdick and others, 2009a; Burdick and Brown, 2010; Burdick, 2012). In all 

3 years of this study, weekly catches of age-1 suckers decreased to zero or near zero by early

September. The initiation of age-1 sucker catches each year roughly coincided with the start of 

sampling, whereas the decrease in catches probably is a result of mortality, emigration from the 

study area, reduced selectivity of this age class, or a combination of these factors.

Catches of age-1, age-2, and older juveniles were too sparse in all 3 years of the study to 

imply patterns in their distribution among habitats. Our data did not indicate a spatial pattern in 

the species ratio for age-1 endangered suckers, nor did they indicate distributional patterns within 

habitats for either species (fig. 7). Three juvenile suckers in 2008, two in 2009, and nine in 2010

captured in our trap nets were judged to be age-2 or older based on weekly length-frequency 

plots. These captures occurred in both lakes and in all three Tulana habitats between May and 

September (Burdick and others, 2009a; Burdick and Brown, 2010; Burdick, 2012).
13

Quantitative Comparisons of Habitat Use by Age-0 Juvenile Suckers

Juvenile suckers use various habitats throughout Upper Klamath Lake, including areas 

near-shore and off-shore, in vegetated and open waters, and over a number of different substrates 

(Terwilliger and others, 2004; Hendrixson and others, 2007; Burdick and others, 2009b). 

Therefore, it was predicted that juvenile suckers would use open water, unvegetated habitats, 

deep water wetlands, and emergent vegetation habitats throughout the Preserve. It was not clear, 

however, if juvenile suckers would use restored and previously established habitat equally. 

Occupancy approaches allowed for quantitative estimates of the portion of restored habitat used 

by juvenile suckers and a method to compare these estimates among various habitats in the 

Preserve and between restored (for example, Goose Bay and Tulana) and established (Upper 

Klamath and Agency Lakes) habitats throughout the lake. In 2008 and 2009, we used single-state 

occupancy models (MacKenzie and others, 2006) to evaluate the effect of depth and habitat (figs. 

1 and 2) on the probability of habitat use. A change in sample design in 2010 allowed us to use 

the extended multi-state version of an occupancy model, with states based on relative abundance 

(MacKenzie and others, 2006). We also redefined our habitat stratification within northern Upper 

Klamath Lake and southern Agency Lake in 2010 by redefining these areas in terms of four 

habitats: Fish Banks, Mid-North, Agency Strait and Agency Near Shore (fig. 3). Therefore, 2010 

data required a separate analysis from 2008 and 2009 data. 

Quantitative Estimation of Sucker Habitat Use

To estimate the portion of habitat used by age-0 juvenile suckers, we used an occupancy

modeling approach (MacKenzie and others, 2006). This approach uses repeat sampling to 

estimate the probability that any one site is used given imperfect detection. In its most general 

form, an occupancy model (MacKenzie and others, 2002) describes the probability of detecting 

the species of interest y times out of k occasions at site i . Modeling is based on encounter 

histories that summarize the samples at each site (for example, 010 indicates that at least one 

sucker was captured in the second sample but none were captured in the other two samples). The 

model is used to jointly estimate the probability of a site being occupied by the species of interest 

(ψ ) and the probability of detecting the species given that it occupies the site (p). We did not 

attempt to generate estimates of habitat use for Goose Bay in 2008 because it was dry.

Several assumptions are necessary for occupancy models to yield unbiased estimates. 

First, the presence of the species of interest and the ability to detect that species when it is 

present are assumed independent between repeated samples at a site. Second, site-specific local 

populations that are susceptible to the sampling gear are assumed to be closed to changes in 

habitat use in the case of single state models used in 2008 and 2009 and in their state of 

abundance (few or many) in the case of multi-state models used in 2010. Because our sampling 

was designed to detect changes in occupancy over time, it is important that sites are closed to 

these changes within but not among weeks. Violation of this closure assumption can result in 

biased estimates of occupancy (MacKenzie and others, 2006; Rota and others, 2009). This 
14

assumption can be relaxed if violations occur randomly among sites, but the resulting probability 

estimates are of habitat use rather than occupancy (MacKenzie and others, 2006). It also is 

necessary to assume that the species of interest is never falsely detected. Species 

misidentification would violate this assumption; therefore, we were unable to model habitat use 

for the two sucker species separately.

Models, which were mathematical descriptions of working hypotheses to explain juvenile 

sucker distributions among habitats and water depth, were constructed in program R (R 

Development Core Team, 2010) and passed to program MARK (version 6.0; White and 

Burnham, 1999) using the RMark package (Laake and Rexstad, 2009; Laake, 2010). Models in 

each model set were ranked using Akaike’s Information Criterion adjusted for small sample size 

(AICc; Burnham and Anderson, 2002) to determine which model in each suite of models was 

most parsimonious given the data. Normalized weights ( ) wi were calculated for each model. 

Normalized model weights can be interpreted as the probability that a particular model is the best 

one in the set for explaining the data, and were used to estimate model-averaged estimates of ψ

(Burnham and Anderson, 2002).

Quantitative Estimates of the Portion of Habitat Used by Age-0 Suckers

Model selection indicated that habitat use differed among weeks and the areas sampled in 

2008 and 2009. There was some model selection uncertainty among the four most parsimonious 

models in 2008, all of which included an additive effect of habitat and week on habitat use (table 

11). The uncertainty among these models is due to minor effects on detection probability. Given 

very small increases in AICc values with additional parameters, we conclude that effects of 

covariates on p in 2008 were minimal. Model selection was much more certain in 2009 with 

nearly all of the weight being assigned to a single model that included an effect of water depth on 

p and an additive effect of habitat and week on ψ (table 12). None of the models with a covariate 

for water depth on ψ carried any weight in either 2008 or 2009 (tables 11 and 12), but almost all 

of our sample sites were in water less than 4 m deep. 

Models indicated that habitat use increased during July in 2008 and 2009. In 2008, the 

portion of used habitat increased between June 23 and July 28 when replicate samples were 

collected. We stopped collecting replicate samples suitable for occupancy analysis at the end of 

July in 2008; however, and were unable to determine if the portion of used habitat continued to 

increase after that time. By the end of July 2008, more than 30 percent of Tulana Submergent 

and northern Upper Klamath Lake, 50 percent of Tulana Open Water, and 80 percent of Tulana 

Emergent and Agency Lake habitats were in use by age-0 juvenile suckers (fig. 10). Because

catch per unit effort increased in all habitats during August, we assume that habitat use also 

continued to increase but we are unable to determine the maximum portion of habitat used. In 

2009, all sampled areas were being used by age-0 suckers by the end of August. The probability 

of habitat use as a function of week reached an asymptote of one in the first week of August in 

2009 in Goose Bay and by late August in all other habitats (fig. 10). Because no data were 

collected in Tulana Emergent or Goose Bay in late August, model parameter estimates for those 

habitats in that time period are based on the data from other habitats. As a result, lines shown in 

figure 10 may not accurately represent age-0 sucker use of Tulana Emergent and Goose Bay 

habitats in late August.
15

Quantitative Estimation of Habitat Use by Low and High Abundances of Age-0 Suckers 

In 2010, we used a multi-state occupancy model (MacKenzie and others, 2006). In this 

scheme, each sample at a site was classified as low (1–5) or high (>5) abundance of suckers, 

with the threshold at 5 based on a natural break in the data. Thus, encounter histories provide 

information about the variability in state classification based on the repeated samples at the site 

(for example, 0HL indicates that suckers were not captured in sample 1, more than five suckers 

were captured in sample 2, and one to five suckers were captured in sample 3).

For comparison of habitat use among habitats within each week we developed a list of 16 

a priori candidate models to describe each dataset (table 13). In cases where the probability of 

ψlow was estimated to be 1 or had estimated standard errors overlapping the upper estimation 

limit of 1 (that is, suckers were present nearly everywhere) in all of the top five models, we fixed 

it at one and eliminated models with covariates for ψlow, reducing the total number of models in 

the set to four. We estimated detection probabilities (p) of high or low abundances of suckers and 

the probability of incorrectly classifying the state of abundance without the addition of 

covariates. We used model averaging over the confidence set of models to estimate probabilities 

of habitat use by a low (1–5; ψlow) or high (>5; ψhigh) abundance of age-0 suckers in each week.

The confidence set of models was defined as the best models in the set that had normalized 

model weights ( ) wi summing to no less than 0.9. We were unable to estimate habitat use in 

Goose Bay or Tulana Emergent in 2010 because these areas became too shallow to sample just 1 

week after age-0 suckers recruited to our nets.

To examine the effect of depth on the probability of the presence of a high abundance of 

age-0 suckers across all weeks and areas, we fit a single model to a pooled dataset. For this 

model, we assumed that suckers existed in low abundance in all areas and all weeks, based on 

the results from the separate weekly models. We fixed ψlow at one and modeled ψhigh as a function 

of depth. We report the relationship between sampling depth and the probability that more than 

five age-0 suckers used a site.

Quantitative Estimates of Habitat Use by Abundance Classes of Age-0 Suckers 

Model selection consistently indicated age-0 suckers were ubiquitous among sampled 

habitats in 2010, but abundance varied among habitats and depths in some weeks. The top-ranked 

models for each week carried the large majority of the model weights between the weeks of August 

9–15 and August 30–September 5 and during the week of September 13-19, but there was more 

model selection uncertainty during the other weeks (table 14). The parameter ψlow was fixed at 1

between the weeks starting August 9 and August 23 and during the week of September 13–19. 

Variation in ψhigh was explained by the categorical habitat covariate during the weeks of August 

9–15 to August 23–29 and by depth during the weeks of August 2–8, August 23–29, and August 

30–September 5.

The probability that at least one age-0 sucker was present at a given site (ψlow) was 

similar among habitats within each week, except the week of August 2–8. During the week of 

August 2–8, sites within the Mid-North and Tulana Submergent habitats had a lower probability 

of being used by one or more age-0 suckers than sites in the Tulana Open Water and Fish Banks 

habitats (table 15). During all other weeks in all habitats the probability of a site being occupied 

by one or more age-0 suckers was at least 0.83. One-half of ψlow estimates were equal to the 

upper estimation limit of 1 and nearly all other estimates had confidence intervals that reached 1. 
16

These high estimates of ψlow are consistent with the high estimated portion of habitat used in 

2008 and 2009. 

Multi-state occupancy models indicated a relatively large portion of habitats were 

occupied by a high abundance (> 5) of age-0 suckers between the weeks of August 16–22 and 

August 23–29, whereas few habitats were occupied by a high abundance during the weeks of 

August 30–September 5 and September 6–12 (table 16). Model selection uncertainty (table 14) 

and large standard errors on estimates during most weeks (table 16) indicate that our ability to 

detect a pattern in habitat use by high abundances of age-0 suckers was limited because catches 

of more than five age-0 suckers were too infrequent. 

Multi-state occupancy modeling indicated that depth did not influence habitat use much 

by a low abundance of age-0 suckers, but high abundances of age-0 suckers occurred more often 

in shallow water than deep water in 2010. To model the effect of depth on habitat use by more 

than five age-0 juvenile suckers, we pooled data over the entire 2010 sampling season and all 

habitats. The portion of habitat used by more than five age-0 suckers decreased only slightly with 

depths between 0.5 and 4.3 m (fig. 12). Previously, researchers indicated that age-0 suckers were 

less likely to use deep water (0.5 m or deeper) (Buettner and Scoppettone, 1990) than shallow 

water (Burdick and others, 2008). Our results indicate that suckers are likely to be present at all 

depths less than or equal to 4.3 m deep, but may be more abundant on the shallower end of this 

range. 

Condition and Health of Juvenile Suckers 

Understanding spatial differences in condition and health of juvenile suckers may 

elucidate the causes behind the continuing problem of poor recruitment, and help assess the 

value of habitats throughout Upper Klamath Lake, including the newly restored habitat in the 

Preserve. Poor water quality or other prolonged environmental factors may cause or exacerbate 

poor juvenile sucker health, which may eventually lead to mortality. 

Afflictions that may be correlated with high rates of mortality in young suckers were 

identified throughout the study area during the first 3 years after restoration. Assessment of 

habitat effects on growth, condition, and health of juvenile suckers, however, was confounded by 

movement of juvenile suckers among habitats in our study area (Burdick and Brown 2010; 

Burdick, 2012). Sucker movement among habitats prevented us from associating fish condition 

at the time of capture to the habitat in which the fish was captured. Nonetheless, juvenile suckers 

captured in all habitats appeared to have similar levels of overall health among the 3 years of our 

study. We cannot make inferences about the condition of juvenile suckers relative to historical 

data because adequate baselines for comparison do not exist.

Skeletal deformities in juvenile suckers in our study are of concern, given their potential 

for lethal side effects, inconsistency with other fish species in the study area, and an increase 

from juvenile suckers collected in Upper Klamath Lake in the early 1990s. The most common 

deformity we observed was shortened opercula, but scoliosis and fused vertebrae also were 

observed in 2010. The portion of age-0 suckers in our study with shortened opercula was greater 

(≥ 6.7 percent; table 17) than what Plunkett and Snyder-Conn (2000) found in 1993 (4.7 percent 

of age-0 Lost River and 1.4–3.1 percent of age-0 shortnose suckers). This deformity was not 

noted for any other species captured in our study, but has been noted for bull trout Salvelinus 

confluentus (Smith and Tinniswood, 2008) and adult suckers (E. Janney, U.S. Geological 

Survey, oral commun., 2011) in the Upper Klamath Basin. Opercle deformities that expose gill 

filaments are a common phenomenon in hatchery fish but are less prevalent in wild fish (Beraldo 
17

and others, 2003). These deformities are non-lethal for hatchery-raised fish (Beraldo and others, 

2003), but may lower resistance to oxygen stress and predispose fish to infections by bacteria, 

parasites, and fungi (Galeotti and others, 2000; Beraldo and others, 2003). Deformed opercula 

could be caused by inbreeding (Winemiller and Taylor, 1982; Tringali and others, 2003), a lack 

of dietary ascorbic acid (Chávez de Martínez, 1990), a lack of dietary calcium (Lindesjoo and 

others, 1994), pollution (Lindesjoo and others, 1994), low environmental pH during periods of 

rapid growth (Lindesjoo and others, 1994), or infestations of digenea (Quist and others, 2007).

There are no data with which to assess the first three of these. Urban pollutants associated with 

deformities in other systems (Lindesjoo and others, 1994) are not known to be present in Upper 

Klamath Lake. In Upper Klamath Lake, daily summertime median pH is rarely less than 8.0 

(Lindenberg and others, 2008), suggesting low pH is not the cause of the deformities we 

observed. We did not examine fish microscopically and therefore were unable to determine if 

deformities were associated with infestations of digenea. Whatever the causal factor, skeletal 

deformities are irreversible (Beraldo and others, 2003). 

The presence of parasitic female anchorworms on juvenile suckers is noteworthy given 

their apparent absence prior to 1996 (Simon and others, 2009), but this parasite is unlikely to 

cause mortality in young suckers. Anchorworm intensity is not associated with deleterious health 

effects for suckers at intensities less than 30 per fish (Robinson and others, 1998). One juvenile 

sucker had an infestation of 34 anchorworms, but otherwise the maximum parasite intensity in 

our 3-year study was 24. Although direct mortality from anchorworms is unlikely, this parasite 

creates a wound at the point of attachment where a secondary infection may occur (Khalifa and 

Post, 1976). 

We documented the length-weight relation of Lost River and shortnose suckers as a gross 

assessment of fish condition during each year of this study, and detected no meaningful 

differences in condition among years (fig. 13). Weight at length assessments, such as this one, 

are only useful in describing extreme changes in body condition. To better understand changes in 

health of juvenile suckers as they relate to restoration, the USGS generated a list of potential 

bacterial pathogens, examined histology, and evaluated the usefulness of TGF-beta protein 

production as an indicator of prolonged stress. A total of 304 bacterial genera was detected in 

skin mucous of age-0 juvenile suckers, several of which are potentially pathogenic (Burdick and 

others, 2009a). Further research is necessary to determine which bacteria pose a serious health 

risk to suckers. A high incidence of poor liver histology in juvenile suckers was coincident with 

high levels of the microcystin cyanotoxin (Vanderkooi and others, 2010), but further research is 

required to determine the nature of this relation. The quality of RNA used to quantify TGF-beta 

decreases with increased air temperatures that typically occur later in the sampling season, and

decreased RNA quality negatively biases estimates of TGF-beta. Therefore, TGF-beta may be of 

little use in identifying temporal trends in juvenile sucker stress unless improved sampling 

methods are developed to address this issue (L. Robertson, U.S. Geological Survey, written 

commun., 2011). 
18

Summary

The Williamson River Delta restoration project successfully recreated habitat for all 

fishes commonly found in Upper Klamath and Agency Lakes. Adverse effects of restoration on 

the fish community in general or on endangered suckers specifically were not detected. The 

quality of restored habitat was at least as suitable for rearing endangered suckers as adjacent lake 

habitats. Although a large number of non-native fishes and fish that could prey on larval suckers 

were captured in the Preserve, they were not more abundant in restored delta than unaltered lake

habitats. The capture of several age classes of juvenile Lost River and shortnose suckers

indicated these species used the restored habitat, at least seasonally, for up to 2 years. 

Quantitative habitat-use estimation that accounted for imperfect detection indicated that all 

restored habitat was used by age-0 juvenile suckers by the end of August each year, but more 

age-0 suckers used shallow rather than deep water.

Acknowledgments 

Data were collected with the help of USGS staff Matt Abel, Caley Boone, Daniel Brown,

Jared Bottcher, Ryan Braham, Travis Ciotti, Ernest Chen, Megan Dethloff, Nathan Harris, Terra 

Kemper, James Latshaw, Randal Loges, Nicholas Miller, Debra Wahrenbrock, Anna Willard and 

Jolene Willis. Greta Blackwood (USGS), Alta Harris (USGS) and Amari Dolan-Caret (USGS) 

helped with database development and management. Craig Ellsworth (USGS), Heather 

Hendrixson (TNC), Douglas Markle (Oregon State University), Torrey Tyler (USBR), Tamara 

Wood (USGS), and Scott VanderKooi (USGS) helped with study design. TNC allowed access to 

the land that much of this study was conducted on and provided us with bathymetry and 

vegetation map data used in this report to map the delta. This work was funded by the Bureau of 

Reclamation (Interagency Agreement 04AA204032) and the U.S. Geological Survey.
19

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25

Figure 1. Geographic location of the Williamson River Delta Preserve Restoration Project in relation to 

other aquatic environments and state boundaries. 
26

Figure 2. Habitats sampled in and adjacent to the Williamson River Delta, Oregon. Habitats within the 

Williamson River Delta were delineated based on vegetation types expected to occur following restoration. 

Goose Bay was sampled for juvenile fish using trap nets in 2009 and 2010; southern Agency Lake, 

northern Upper Klamath Lake, and Emergent, Submergent, and open water habitats in Tulana were 

sampled for juvenile fish from 2008 to 2010; southern Agency Lake, northern Upper Klamath Lake, and 

Emergent, and Open water habitats in Tulana for larval fish in 2008 and 2009. 
27

Figure 3. Locations of nine sampling areas and sites sampled with trap nets during summer 2010 in Upper 

Klamath Lake, Agency Lake, and the Williamson River Delta Preserve, Oregon. 
28

Figure 4. Schematic boxplots of standard length of yellow perch and age-0 juvenile suckers, captured in 

the Williamson River Delta, Oregon, and adjacent lake habitats, 2008–10. The line indicates the minimum 

size a yellow perch would need to be to prey on the smallest age-0 sucker captured in trap nets in a given 

week. 
29

Figure 5. Locations where larval Lost River suckers (LRS) and larvae identified as either shortnose or 

Klamath largescale suckers (SNS-KLS) were captured in Agency Lake, Upper Klamath Lake, and the 

Williamson River Delta Preserve, Oregon, 2008–09. Sampling for larval suckers did not occur in Goose Bay 

or South Marsh habitats, located to the southeast of the Williamson River. 
30

Figure 6. Number of larval Lost River and shortnose or Klamath largescale suckers caught per cubic meter 

of water filtered, by week in 2008 and 2009, in two habitats in the Williamson River Delta Preserve (Tulana 

Emergent and Tulana Open Water), in Upper Klamath Lake, and in Agency Lake, Oregon. 
31

Figure 7. Locations that age-0 and age-1 Lost River suckers and shortnose suckers were captured in

trap-net sampling in the Williamson River Delta, Oregon, and adjacent lake habitats, 2008–10. 
32

Figure 8. Schematic boxplots showing timing of age-0 sucker catches in trap nets set in four habitats in the 

Williamson River Delta Preserve and in northern Upper Klamath Lake, and in southern Agency Lake, 

Oregon, 2008–10. The Goose Bay habitat was not inundated in 2008 and therefore not sampled. The 

absence of data in the Tulana Emergent habitat in 2010, however, is due to a lack of age-0 suckers 

captured there in that year. 
33

Figure 9. Schematic boxplots showing timing of age-1 sucker catches in trap nets set in four habitats in the 

Williamson River Delta Preserve and in northern Upper Klamath Lake, and in southern Agency Lake, 

Oregon, 2008–10. The Goose Bay habitat was not inundated in 2008 and therefore not sampled. The 

absence of data in northern Upper Klamath Lake in 2010, however, is due to a lack of age-1 suckers 

captured there in that year.
34

Figure 10. Estimated portion of habitat used by age-0 juvenile suckers in the Williamson River Delta 

Preserve and two adjacent lake habitats, Oregon, over time in 2008. Estimates are based on model 

averaging. Gray bars indicate the number of age-0 suckers captured per net set in each week. The portion 

of used habitat is an estimate in which imperfect detection has been accounted for. Therefore, all habitat 

can be in use when catch rates are fewer than one fish per net. The location of habitats is shown in 

figure 2.
35

Figure 11. Estimated portion of habitat used by age-0 juvenile suckers in the Williamson River Delta

Preserve and two adjacent lake habitats, Oregon, over time in 2009. Estimates are based on model 

averaging. Gray bars indicate the number of age-0 suckers captured per net set in each week. The portion 

of used habitat is an estimate in which imperfect detection has been accounted for. Therefore, all habitat 

can be in use when catch rates are fewer than one fish per net. The location of habitats is shown in figure 

2. 
36

Figure 12. Estimated probability that a sample site in Upper Klamath Lake, Agency Lake, or the Williamson 

River Delta, Oregon, was used in 2010 by more than five age-0 suckers at a given depth. Probability was 

estimated using a multistate occupancy model in which the probability that each site is used by at least one 

to five age-0 suckers was fixed at one. 95-percent confidence limits are shown. 
37

Figure 13. Schematic box plots showing age-0 Lost River and shortnose sucker weight in 10 mm length 

bins, captured in Agency Lake, Upper Klamath Lake, and the Williamson River Delta, Oregon, 2008–10. 
38

Table 1. Number of fish species, excluding endangered suckers, captured in trap nets each year in six

habitats sampled in and adjacent to the Williamson River Delta, Oregon.

[Goose Bay was dry and therefore not sampled in 2008 and data were not collected on fishes other than suckers in 

southern Agency Lake in 2010. A species list is given in table 2. --, no data]

Habitat

Number of species detected

2008 2009 2010 Total

Southern Agency Lake 11 13 -- 13

Northern Upper Klamath Lake 12 13 10 13

Tulana Emergent 10 12 11 13

Tulana Submergent 12 12 10 13

Tulana Open Water 11 10 10 11

Goose Bay -- 13 10 14
39

Table 2. Characteristics of fishes, excluding endangered suckers, captured in and adjacent to the 

Williamson River Delta, Oregon.

[Fish were captured in trap nets or larval trawls. Life stages detected: A, adult, J, juvenile, and L, larval. 

Abundance: A qualitative classification based on the number of fish captured. Sucker life stage at risk of predation: 

An assumption based on diet and feeding behavior reported in the literature for each species. TL: total length. mm: 

millimeter]

Common name Latin name

Native or nonnativeLife Stages 

Detected Abundance Diet 

Sucker life stage at 

risk of predation

blue chub Gila coerulea Native A,J,L Abundant Algae, detritus, 

invertebrates, and fish 

(Bond and others, 

1968)

Larval

brown bullhead Ameiurus 

nebulosus

Non-native A,J,L Common Invertebrates (Kline 

and Wood, 1996)

None

fathead minnow Pimephales 

promelas

Non-native A,J,L Abundant Algae, invertebrates, 

zooplankton, detritus, 

larval suckers (Markle 

and Dunsmoor, 2007)

Larval

Klamath Lake 

sculpin

Cottus princeps Native A,J

1 Common Invertebrates (Bond 

and others, 1968)

None

Klamath 

largescale 

sucker

Catostomus 

snyderi

Native J,L Very rare Probably invertebrates 

(Markle and Clauson, 

2006)

None

Klamath 

redband trout

Oncorhynchus 

mykiss subsp.

Native J Rare Invertebrates and fish 

(Bond and others, 

1968)

Larval and juvenile

Klamath 

speckled dace

Rhinichthys 

osculus 

klamathensis

Native A Very rare Invertebrates (Angradi 

and others, 1991)

None

Klamath tui 

chub

Siphatales 

bicolor bicolor

Native A,J,L Abundant Algae, detritus, and 

invertebrates (Bond 

and others, 1968, 

Koch, 1973)

Larval2 and egg

largemouth 

bass

Micropterus 

salmoides

Non-native J Very rare Invertebrates and fish 

(Dibble and Harrell, 

1997)

Larval and juvenile 

suckers up to about 

150 mm TL 

(Johnson and Post, 

1996)

Sunfish

(bluegill or 

pumpkinseed)

Lepomis sp. Non-native A,J Rare Invertebrates and fish 

(Garcia-Berthou and 

Moreno-Amich, 2000)

Larval

slender sculpin Cottus tenuis Native A,J1 Rare Invertebrates (Bond 

and others, 1968)

None

unidentified 

species of 

lamprey

Lampetra sp. Native A Rare Parasitic (Beamish, 

1980)

Juvenile and adult

Upper Klamath 

marbled sculpin

Cottus 

klamathensis 

klamathensis

Native A,J

1 Abundant Invertebrates (Bond 

and others, 1968)

None

yellow perch Perca 

flavescens

Non-Native A,J,L Abundant Invertebrates and fish 

(Bond and others, 

1968)

Larval and juvenile 

suckers up toabout 

about 121 mm TL 

(Truemper and 

Lauer, 2005)

1

Larval and juvenile sculpin were only identified to genus. 2

Bond and others (1968) found fish in the diets of blue chub but not tui chub collected from Upper Klamath Lake. Koch 1973 reported that 

tui chub ate cui-ui sucker eggs.
40

Table 3. Ratio of the number of juvenile or small adult fish that potentially prey on larval suckers to those 

that do not prey on larval suckers, captured in and adjacent to the Williamson River Delta, Oregon, 2008–

10.

[Locations of these areas are shown in figure 2. --, no data]

Habitat 2008 2009 2010

Tulana Emergent 23 30 110

Tulana Submergent 51 216 69

Tulana Open Water 60 441 49

Goose Bay -- 60 35

Southern Agency Lake 28 141 --

Northern Upper Klamath Lake 9 23 22

Table 4. Ratio of the number of juvenile or small adult fish that potentially prey on age-0 juvenile suckers 

to those that do not prey on age-0 juvenile suckers, captured in and adjacent to the Williamson River 

Delta, Oregon, 2008–10.

[Locations of these areas are shown in figure 2. –, no data]

Habitat 2008 2009 2010

Tulana Emergent 0.13 0.06 0.01

Tulana Submergent 0.10 0.01 0.03

Tulana Open Water 0.15 0.01 0.15

Goose Bay -- 0.21 0.01

Southern Agency Lake 0.15 0.00 --

Northern Upper Klamath Lake 0.16 0.02 0.03

Table 5. Ratio of the number of native fish to non-native fish, captured in and adjacent to the Williamson 

River Delta, Oregon, 2008–10.

[Locations of these areas are shown in figure 2. –, no data]

Habitat 2008 2009 2010

Tulana Emergent 1.33 0.87 1.54

Tulana Submergent 0.75 0.08 0.66

Tulana Open Water 0.61 0.08 0.52

Goose Bay -- 0.37 1.10

Southern Agency Lake 1.36 0.08 --

Northern Upper Klamath Lake 1.45 0.63 1.60
41

Table 6. Percentage of nets set in and adjacent to the Williamson River Delta that captured Lost River 

sucker larvae and larvae identified as either shortnose or Klamath largescale sucker, Oregon, 2008–09. 

[Locations of these areas are shown in figure 2]

2008 2009

Area SNS-KLS LRS SNS-KLS LRS

Agency Lake 5 5 5 5

Upper Klamath Lake 14 16 19 4

Tulana Open Water 4 10 0 9

Tulana Emergent 50 50 63 25

Table 7. Ratio of larvae identified as Lost River suckers to those identified as either shortnose or Klamath 

largescale suckers collected in four sampling areas in and adjacent to the Williamson River Delta, Oregon, 

2008–09. 

[Locations of these areas are shown in figure 2]

Area 2008 2009

Agency Lake 1.50 0.50

Upper Klamath Lake 5.86 0.05

Tulana Open Water 2.00 no SNS-KLS

Tulana Emergent 3.83 0.02

Table 8. Ratio of age-0 juvenile Lost River suckers to shortnose suckers collected in six sampling areas in 

and adjacent to the Williamson River Delta, Oregon, 2008–10. 

[Northern Upper Klamath Lake and southern Agency Lake were not divided into smaller sampling units in 2008 

and 2009. Therefore, to facilitate comparisons the 2010 Fish Banks and Mid-North habitats were combined under 

the heading of northern Upper Klamath Lake and the 2010 Agency Near Shore and Agency Strait were combined 

under the heading of southern Agency Lake. Sampling areas are shown in figures 2 and 3]

Area 2008 2009 2010

Southern Agency Lake 2.43 0.15 1.80

Northern Upper Klamath Lake 0.42 1.68 0.46

Tulana Open Water 0.23 0.20 0.29

Tulana Submergent 0.28 0.11 0.40

Tulana Emergent 5.25 1.00 no suckers

Goose Bay dry 0.53 all SNS
42

Table 9. Number of age-0 suckers caught per net set in each of six areas in and adjacent to the 

Williamson River Delta, Oregon, 2008–10.

[Northern Upper Klamath Lake and southern Agency Lake were not divided into smaller sampling units in 2008 

and 2009. Therefore, to facilitate comparisons, the 2010 Fish Banks and Mid-North habitats were combined under 

the heading of northern Upper Klamath Lake, and the 2010 Agency Near Shore and Agency Strait were combined 

under the heading of southern Agency Lake. Sampling areas are shown in figures 2 and 3. --, no data]

Area 2008 2009 2010

Southern Agency Lake 0.263 0.183 0.587

Northern Upper Klamath Lake 0.257 0.192 1.016

Tulana Emergent 0.177 0.042 0.000

Tulana Open Water 0.489 0.331 0.917

Tulana Submergent 0.245 0.427 0.425

Goose Bay -- 0.644 0.025

Table 10. Number of age-1 suckers caught per net set in each of six areas in and adjacent to the 

Williamson River Delta, Oregon, 2008–10.

[Northern Upper Klamath Lake and southern Agency Lake were not divided into smaller sampling units in 2008 

and 2009. Therefore, to facilitate comparisons, the 2010 Fish Banks and Mid-North areas were combined under the 

heading of northern Upper Klamath Lake, and the 2010 Agency Near Shore and Agency Strait areas were combined 

under the heading of southern Agency Lake. Sampling areas are shown in figures 2 and 3. –, no data]

Area 2008 2009 2010

Southern Agency Lake 0.015 0.055 0.005

Northern Upper Klamath Lake 0.031 0.053 0.000

Tulana Emergent 0.025 0.352 0.067

Tulana Open Water 0.087 0.070 0.003

Tulana Submergent 0.045 0.080 0.008

Goose Bay -- 0.287 0.045
43

Table 11. Models fit to age-0 sucker habitat use data collected the Williamson River Delta, Oregon, and 

adjacent lake habitats, 2008.

[Each model is a mathematical description of a working hypothesis about the effects of covariates on habitat use (ψ) 

and detection probability (p). Habitats included: southern Agency Lake, northern Upper Klamath Lake, Tulana 

Emergent, Tulana Submergent, and Tulana Open Water (fig. 2). Covariate effects are listed after each parameter in 

the model name. A dot indicates no covariate effects were tested for a particular parameter within a model. Akaike's 

Information Criteria adjusted for small sample size is given (AICc) along with the difference in this value between 

the most parsimonious model and the given model (Delta AICc). Model weights are the probability that a given 

model is the most parsimonious model in the set to explain the data]

Model

Number of 

parameters AICc DeltaAICc Weight

p(.)Ψ (habitat + week) 7 318.5 0 0.43

p(week) Ψ (habitat + week) 8 319.0 0.5 0.34

p(depth) Ψ (habitat + week) 8 320.6 2.1 0.15

p(habitat)Ψ(habitat + week) 11 322.0 3.5 0.08

p(habitat)Ψ(week) 7 326.3 7.8 0.01

p(week)Ψ(.) 3 340.1 21.6 0.00

p(week)Ψ(depth) 4 341.8 23.3 0.00

p(.)Ψ(week) 3 341.9 23.3 0.00

p(week)Ψ(week) 4 342.1 23.6 0.00

p(depth)Ψ(week) 4 343.1 24.6 0.00

p(.)Ψ(habitat) 6 346.3 27.8 0.00

p(depth)Ψ(habitat) 7 348.3 29.8 0.00

p(habitat)Ψ(.) 6 352.0 33.5 0.00

p(habitat)Ψ(depth) 7 354.1 35.5 0.00

p(.)Ψ(.) 2 360.5 42.0 0.00

p(depth)Ψ(.) 3 360.8 42.2 0.00

p(.)Ψ(depth) 3 361.3 42.8 0.00

p(depth)Ψ(depth) 4 362.8 44.3 0.00
44

Table 12. Models fit to age-0 sucker habitat use data collected the Williamson River Delta, Oregon, and 

adjacent lake habitats, 2009.

[Each model is a mathematical description of a working hypothesis about the effects of covariates on habitat use (ψ) 

and detection probability (p). Habitats included: southern Agency Lake, northern Upper Klamath Lake, Tulana 

Emergent, Tulana Submergent, Tulana Open Water, and Goose Bay (fig. 2). Covariate effects are listed after each 

parameter in the model name. A dot indicates no covariate effects were tested for a particular parameter within a 

model. Akaike's Information Criteria adjusted for small sample size is given (AICc) along with the difference in this 

value between the most parsimonious model and the given model (Delta AICc). Model weights are the probability 

that a given model is the most parsimonious model in the set to explain the data]

Model

Number of 

parameters AICc DeltaAICc Weight

p(depth)Ψ(habitat + week) 9 1,155.8 0 0.99

p(.)Ψ(habitat + week) 8 1,166.7 10.9 0.00

p(week)Ψ(habitat + week) 9 1,166.8 11.0 0.00

p(habitat)Ψ(week) 8 1,179.2 23.4 0.00

p(depth)Ψ(week) 4 1,193.9 38.0 0.00

p(.)Ψ(week) 3 1,204.6 48.8 0.00

p(week)Ψ(week) 4 1,206.3 50.4 0.00

p(week)Ψ(depth) 4 1,247.6 91.8 0.00

p(week)Ψ(.) 3 1,256.8 101.0 0.00

p(habitat)Ψ(depth) 8 1,289.4 133.5 0.00

p(depth)Ψ(habitat) 8 1,301.0 145.1 0.00

p(depth)Ψ(depth) 4 1,301.9 146.0 0.00

p(.)Ψ(depth) 3 1,303.5 147.7 0.00

p(depth)Ψ(.) 3 1,306.6 150.7 0.00

p(habitat)Ψ(.) 7 1,306.7 150.8 0.00

p(habitat)Ψ(habitat) 12 1,310.1 154.3 0.00

p(.)Ψ(habitat) 7 1,311.5 155.6 0.00

p(.)Ψ(.) 2 1,321.4 165.6 0.00
45

Table 13. Explanatory habitat use models fit to age-0 sucker categorical abundance data collected from 

the Williamson River Delta, Oregon, and adjacent habitats, 2010.

[Models have parameters for low (1-5 age-0 suckers; Ψlow) and high (> 5 age-0 suckers; Ψhigh) states of abundance, 

the probability of detecting each of these states (pi), and the probability of observing a high abundance when a high 

abundance was present (δ). Parentheses after each parameter indicate covariates specific to that parameter. A dot 

indicates no covariates were applied to a parameter. Habitats included: Tulana Emergent, Tulana Submergent, 

Tulana Open Water, Agency Strait, Agency Near Shore, Fish Banks, and Mid North (figs. 2 and 3)] 

Model

Ψlow (.) Ψhigh (.) plow(.)phigh(.)δ (.)

Ψlow (habitat) Ψhigh (habitat) plow(.)phigh(.)δ (.)

Ψlow (depth) Ψhigh (habitat) plow(.)phigh(.)δ (.)

Ψlow (habitat+depth) Ψhigh (habitat) plow(.)phigh(.)δ (.)

Ψlow (.) Ψhigh (habitat) plow(.)phigh(.)δ (.)

Ψlow (habitat) Ψhigh (depth) plow(.)phigh(.)δ (.)

Ψlow (depth) Ψhigh (depth) plow(.)phigh(.)δ (.)

Ψlow (habitat+depth) Ψhigh (depth) plow(.)phigh(.)δ (.)

Ψlow (.) Ψhigh (depth) plow(.)phigh(.)δ (.)

Ψlow (habitat) Ψhigh (habitat+depth) plow(.)phigh(.)δ (.)

Ψlow (depth) Ψhigh (habitat+depth) plow(.)phigh(.)δ (.)

Ψlow (habitat+depth) Ψhigh (habitat+depth) plow(.)phigh(.)δ (.)

Ψlow (.) Ψhigh (habitat+depth) plow(.)phigh(.)δ (.)

Ψlow (habitat) Ψhigh (.) plow(.)phigh(.)δ (.)

Ψlow (depth) Ψhigh (.) plow(.)phigh(.)δ (.)

Ψlow (habitat+depth) Ψhigh (.) plow(.)phigh(.)δ (.)
46

Table 14. The confidence set of models fit to age-0 sucker categorical abundance data collected in the 

Williamson River Delta, southern Agency Lake, and northern Upper Klamath Lake, Oregon, 2010. 

[The probability of a model being the most accurate of the models fit to data from each week (wi) is given. Only the 

most parsimonious models with wis summing to at least 0.9 (the confidence set) are shown. Models had parameters 

for low (1-5 age-0 suckers; Ψlow) and high (> 5 age-0 suckers; Ψhigh) states of occupancy, the probability of detecting 

each of these states (pi), and the probability of observing a high abundance when a high abundance was present (δ). 

Parentheses after each parameter indicate covariates specific to that parameter. A dot indicates no covariates were 

applied to a parameter. If standard errors overlapped one, the upper estimation limit for Ψlow the parameter was fixed 

at one and indicated by a one in the parentheses.]

Week Most parsimonious models wi

2-Aug Ψlow (habitat) Ψhigh (depth) plow(.)phigh(.)δ (.) 0.42

Ψlow (habitat) Ψhigh (.) plow(.)phigh(.)δ (.) 0.21

Ψlow (habitat+depth) Ψhigh (depth) plow(.)phigh(.)δ (.) 0.14

Ψlow (habitat+depth) Ψhigh (.) plow(.)phigh(.)δ (.) 0.09

Ψlow (habitat) Ψhigh (habitat) plow(.)phigh(.)δ (.) 0.08

9-Aug Ψlow (1)Ψhigh (habitat) plow(.)phigh(.)δ (.) 0.79

Ψlow (1)Ψhigh (habitat+depth) plow(.)phigh(.)δ (.) 0.21

16-Aug Ψlow (1)Ψhigh (habitat) plow(.)phigh(.)δ (.) 0.71

Ψlow (1)Ψhigh (habitat+depth) plow(.)phigh(.)δ (.) 0.15

Ψlow (1)Ψhigh (depth) plow(.)phigh(.)δ (.) 0.11

23-Aug Ψlow (1)Ψhigh (habitat+depth) plow(.)phigh(.)δ (.) 0.91

30-Aug Ψlow (.)Ψhigh (depth) plow(.)phigh(.)δ (.) 0.64

Ψlow (depth)Ψhigh (depth) plow(.)phigh(.)δ (.) 0.15

Ψlow (.)Ψhigh (habitat) plow(.)phigh(.)δ (.) 0.12

6-Sep Ψlow (.)Ψhigh (.)plow(.)phigh(.)δ (.) 0.42

Ψlow (depth)Ψhigh (.)plow(.)phigh(.)δ (.) 0.27

Ψlow (.)Ψhigh (depth)plow(.)phigh(.)δ (.) 0.13

Ψlow (depth)Ψhigh (depth)plow(.)phigh(.)δ (.) 0.08

13-Sep Ψlow (1)Ψhigh (.)plow(.)phigh(.)δ (.) 0.89

Ψlow (1)Ψhigh (habitat)plow(.)phigh(.)δ (.) 0.09
47

Table 15. Estimated portion of habitats used each week in 2010 by at least one age-0 sucker (ψlow). 

[Model averaged estimated probabilities (ψlow) and their standard errors (SE) are given. The confidence set of 

models (table 14) was used in model averages. If estimates were equal to the upper estimation limit of one ψlow was 

fixed at one and the standard error was not estimated. These boundary estimates are marked with an asterisk. We 

refined our habitat stratification between 2009 and 2010, such that Fish Banks and Mid-North are within the former 

Upper Klamath Lake habitat and Agency Strait and Agency Near Shore are within former Agency Lake (figs. 2 and 

3). --, no data]

Week Fish Banks Mid-North Agency Strait

Agency Near 

Shore

Tulana Open 

Water

Tulana 

Submergent

Ψlow SE Ψlow SE Ψlow SE Ψlow SE Ψlow SE Ψlow SE

Aug 02 0.97 0.13 0.62 0.22 0.97 0.10 0.29 0.14

Aug 09 1.00* -- 1.00* -- 1.00* -- 1.00* --

Aug 16 1.00* -- 1.00* -- 1.00* -- 1.00* --

Aug 23 1.00* -- 1.00* -- 1.00* -- 1.00* --

Aug 30 0.90 0.08 0.91 0.07 0.91 0.06 0.91 0.07

Sep 06 0.83 0.12 0.83 0.12 0.83 0.12 0.83 0.12

Sep 13 1.00* -- 1.00* -- 1.00* -- 1.00* --
48

Table 16. Estimated portion of habitats used each week in 2010 by more than five age-0 suckers (ψhigh). 

[Model-averaged estimated probabilities (ψhigh) and their standard errors (SE) are given. If the model averaged 

estimate of ψlow was at or near the upper estimation boundary of one (table 15) it was fixed at one, leaving only four 

models remaining in the set. The confidence set of models was used in model averages, and was defined as the most 

parsimonious models with weight summing to at least 0.9 (table 14). Standard errors could not be calculated if 

estimates in any of the models being used in averages were equal to the upper boundary of one or lower boundary of 

zero in any of the confidence set of models (Aug. 30). We refined our habitat stratification between 2009 and 2010, 

such that Fish Banks and Mid North are within the former Upper Klamath Lake habitat and Agency Strait and 

Agency Near Shore are within former Agency Lake (figs. 2 and 3). --, no data]

Week Fish Banks Mid North Agency Strait

Agency Near 

Shore

Tulana Open 

Water

Tulana 

Submergent

Ψhigh SE Ψhigh SE Ψhigh SE Ψhigh SE Ψhigh SE Ψhigh SE

Aug 02 0.24 0.10 0.24 0.10 0.24 0.10 0.24 0.10

Aug 09 0.10 0.11 0.14 0.09 1.00 -- 0.11 0.11

Aug 16 0.81 0.29 0.07 0.18 0.75 0.24 0.33 0.20

Aug 23 0.54 0.25 0.00 -- 1.00 -- 1.00 --

Aug 30 0.17 -- 0.04 -- 0.04 -- 0.06 0.07

Sep 06 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

Sep 13 0.58 0.64 0.45 0.06 0.49 0.65 0.45 0.64

Table 17. Percentage of juvenile suckers collected from Upper Klamath Lake, Agency Lake, and the 

Williamson River Delta, Oregon, 2008–10 to have one or more deformed opercula in each year.

Age class 2008 2009 2010

Age-0 6.7 9.0 7.0

Age-1 9.0 7.0 9.0
49

Appendix - List of Products

List of products produced under or in association with Interagency Agreement 07AA200135 

with the Bureau of Reclamation.

Journal Articles

Burdick, S.M., 2011, Tag loss and short-term mortality associated with passive integrated 

transponder (PIT) tagging of juvenile Lost River suckers: North American Journal of Fisheries 

Management, v. 31, p. 1,088–1,092. 

Robertson, L.S., Ottinger, C.A., Burdick, S.M., and VanderKooi, S.P., in press, Development of 

a quantitative assay to measure expression of transforming growth factor β1 (TGF-β) in Lost 

River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) and evaluation 

of potential pitfalls in use with field-collected samples: Journal of Fish and Shellfish 

Immunology.

Wood, T.M., Hendrixson, H.A., Markle, D., Erdman, C., Burdick, S.M., and Ellsworth, C., in

review, Validation of a model to simulate larval sucker transport and retention in a recently 

restored river delta, Upper Klamath Lake, Oregon: Ecological Applications.

Peer Reviewed Reports

Burdick, S.M, 2012, Distribution and condition of larval and juvenile Lost River and shortnose 

suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon—

2010 annual data summary: U.S. Geological Survey Open-File Report 2012-1027, 39 p. (Also 

available at http://pubs.usgs.gov/of/2012/1027/.)

Burdick, S.M., and Brown, D.T., 2010, Distribution and condition of larval and juvenile Lost 

River and shortnose suckers in the Williamson River Delta Restoration Project and Upper 

Klamath Lake, Oregon—2009 Annual Data Summary: U.S. Geological Survey Open-File 

Report 2010-1216, 78 p. (Also available at http://pubs.usgs.gov/of/2010/1216/.) 

Burdick, S.M., Ottinger, C., Brown, D.T., VanderKooi, S.P., Robertson, L., and Iwanowicz, D., 

2009, Distribution, health, and development of larval and juvenile Lost River and shortnose 

suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon—

2008 annual data summary: U.S. Geological Survey Open-File Report 2009-1287, 76 p. (Also 

available at http://pubs.usgs.gov/of/2009/1287/.)

Wood, T.M., Hendrixson, H.A., Markle, D.F., Erdman, C.S., Burdick, S.M., Ellsworth, C.M., 

and Buccola, N.L., 2011, Dispersal of larval suckers at the Williamson River Delta, Upper 

Klamath Lake, Oregon, 2006-09: U.S. Geological Survey Scientific Investigations Report 

2012-5016, 28 p. (Also available at http://pubs.usgs.gov/sir/2012/5016/.)
50

Fact Sheet

VanderKooi, S.P., Burdick, S.M., Echols, K.R., Ottinger, C.A., Rosen, B.H., and Wood, T.M., 

2010, Algal toxins in Upper Klamath Lake, Oregon—Linking water quality to juvenile 

sucker health: U.S. Geological Survey Fact Sheet 2009-3111, 2 p. (Also available at

http://pubs.usgs.gov/fs/2009/3111/.)

Presentations

Bottcher, J., and Burdick, S.M., 2011, Distribution of age-1 suckers relative to dissolved-oxygen 

in Upper Klamath Lake, Oregon: American Fisheries Society Annual Meeting, Platform 

Presentation, Seattle, Washington, March 7, 2011.

Bottcher, J., and Burdick S.M., 2011, Distribution of age-1 suckers relative to dissolved-oxygen 

in Upper Klamath Lake, Oregon: Pacific Northwest Science Conference, Platform 

Presentation, Vancouver, Washington, March 2, 2011.

Burdick, S.M., 2009, Ecology of juvenile lake suckers in Upper Klamath Lake, Oregon: Invited 

Platform Presentation, Upper Klamath Lake Cyanotoxin Working Group, Seattle, Washington,

December 7, 2009.

Burdick, S.M., 2009, Estimating habitat use and distribution of two rare suckers in Upper 

Klamath Lake, Oregon: Invited Platform Presentation, Klamath Science Team, Sacramento, 

California, March 17, 2009.

Burdick, S.M. and D.T. Brown. 2009. Retention of larval endangered Lost River and shortnose 

suckers in the restored Williamson River Delta. Platform Presentation. United States 

Geological Survey Northwest Science Conference. Portland, Oregon. March 5 2009.

Burdick, S.M., and D. Hewitt. 2010. Can space replace time in occupancy studies when the 

method of detection requires retaining individuals? The American Fisheries Society Annual 

Meeting, Landscape and Fish Habitat Relationships Symposium, Platform Presentation. 

Pittsburgh, Pennsylvania. September, 16, 2010.

Burdick, S.M. 2010. Larval and Juvenile Sucker Studies in Upper Klamath Lake, Oregon. 

Briefing to the U.S. Bureau of Reclamation. Klamath Falls, Oregon. April 6, 2010.

Burdick, S.M. 2010. Lack of recruitment to spawning sucker populations and timing of juvenile 

sucker mortality in Upper Klamath Lake, Oregon. Invited Platform Presentation. Klamath 

Basin Science Conference. Medford, Oregon. February 3, 2010.

Burdick, S.M., N.P. Banish, E. Willy, and D.A. Hewitt. 2011. Distribution of the endemic 

slender sculpin relative to habitat variables within Upper Klamath Lake, Oregon. American 

Fisheries Society Annual Meeting, Platform Presentation. Seattle, Washington. September 7, 

2011.

Carter, J.L., and Fend, S.V. 2009. Benthic invertebrates of Upper Klamath Lake, OR: The 

Chironomidae. Upper Klamath Lake Cyanotoxin Working Group. Seattle, Washington. 

December 7, 2009. Invited Platform Presentation.

Carter, J.L., and Fend, S.V. 2010. Within-year and among-year distributions of benthic 

invertebrates in Upper Klamath Lake and the newly restored delta wetlands: Klamath Basin 

Science Conference, February 1-5, 2010, Medford, Oregon. Invited Platform Presentation.

Densmore, C.L., C.A. Ottinger, K.R. Echols, T.M. Wood, S.P. VanderKooi, B.H. Rosen, and 

S.M. Burdick. 2010. Algal Toxins in Upper Klamath Lake, Oregon: Histopathology of age-0 

Lost River and shortnose suckers in 2007 and 2008. Invited Platform Presentation. Klamath 

Basin Science Conference, Medford, OR, Feb 1-5.
51

Echols, K.R., T.M. Wood, C.A. Ottinger, B.H. Rosen, S.M. Burdick, and S.P. Vanderkooi. 2010. 

Cyanobacterial Toxins Found in Upper Klamath Lake, Oregon: Implications for Endangered

Fish. Invited Platform Presentation. Klamath Basin Science Conference, Medford, OR, Feb 1-

5.

Eldridge, S.L.C, K.E. Kannarr, T.M. Wood, K.R. Echols, B.H. Rosen, S.M. Burdick, C.A. 

Ottinger, and S.P. VanderKooi. 2010. Seasonal and Spatial Dynamics of Cyanobacteria and 

Associated Water Quality Variables in Upper Klamath Lake, Oregon. Invited Platform 

Presentation. Klamath Basin Science Conference, Medford, OR, Feb 1-5.

Erdman, C.S., T.M. Wood, H. Hendrixson, D.F. Markle, S.M. Burdick, and C. Ellsworth, 2012, 

Understanding the Impact of a Restored Delta in Upper Klamath Lake, Oregon on Larval 

Sucker Transport through the Use of a Hydrodynamic and Larval Transport Model. Oregon 

Chapter of the American Fisheries Society Annual Meeting, Platform Presentation, Eugene, 

Oregon, March 1, 2012.

Iwanowicz, D.D., C.A. Ottinger, K.R. Echols, T. Wood, S.P. VanderKooi, B.H. Rosen, and S.M. 

Burdick. 2010. Skin bacterial flora of age-0 Lost River and shortnose suckers in 2008: Nature 

Conservancy Delta Restoration Project and Upper Klamath Lake. Invited Platform 

Presentation. Klamath Basin Science Conference, Medford, OR, Feb 1-5.

Markle, D.F., T.M. Wood, N. Buccola, S.M. Burdick, C. Ellsworth, C. Erdman, H. Hendrixson. 

2011. Modeling transport of larval suckers through a restored delta in Upper Klamath Lake, 

Oregon, using density-based and individual-based approaches. American Fisheries Society 

Larval Fish Conference, Platform Presentation. Wilmington, North Carolina. May 22, 2011.

Rosen, B.H. 2010. Direct and Indirect Consumption of Cyanobacteria by Juvenile Suckers in 

Klamath Lake, Oregon. Invited Platform Presentation. Klamath Basin Science Conference, 

Medford, OR, Feb. 1-5.

Rosen, B.H. 2010. Ecological Strategies Utilized by Cyanobacteria. Invited Platform 

Presentation. Klamath Basin Science Conference, Medford, OR, Feb 1-5.

VanderKooi, S.P., S.M. Burdick, and C.M. Ellsworth. 2009. The effects of habitat restoration on 

endangered fishes in the Upper Klamath Basin. Invited Platform Presentation. American 

Geophysical Union Fall Meeting. December 18, 2009.

VanderKooi, S.P. 2009. USGS fisheries research in the Klamath River Basin. Invited 

Presentation. Dept. of Interior Science Scoping Meeting: Klamath Network and Environs. 

Redding, CA. November 17, 2009.

VanderKooi, S.P. and C.A. Ottinger. 2009. Algal toxins and their effects on juvenile endangered 

Lost River and shortnose suckers in Upper Klamath Lake, Oregon. The American Fisheries 

Society Annual Meeting. Contributed Presentation. Contaminants and Toxicology Symposium. 

Nashville, TN. August 31, 2009.

VanderKooi, S.P. 2010. Biology and current status of Lost River and shortnose suckers. Invited 

Presentation. Klamath River Dam Removal – Resident Fish Expert Panel. Klamath Falls, OR. 

August 2, 2010.

Wood, T.M., Markle, D.F., T.M. Wood, N. Buccola, S.M. Burdick, C. Ellsworth, C. Erdman, H. 

Hendrixson. 2011. Modeling transport of larval suckers through a restored delta in Upper 

Klamath Lake, Oregon, using density-based and individual-based approaches. American 

Fisheries Society Annual Meeting, Platform Presentation. Seattle, Washington. September 7, 

2011.

Wood, T., and S.M. Burdick. 2009. The effects of hydrodynamics on larval sucker distribution in 

the Williamson River Delta restoration area, Oregon. Invited Platform Presentation. Klamath 

Science Team. Sacramento, California. March 17 2009.
52

Posters

Burdick, S.M., Wahrenbrock, D. and Bottcher, J. 2011. Readability of daily increments on 

sagittal and lapilliar otoliths of wild Lost River, shortnose and Klamath largescale sucker 

larvae. Pacific Northwest Science Conference. Vancouver, Washington, March 3, 2011.

Brown, D., S. Wong, S. Burdick, and H. Hendrixson. 2010. Effects of Low Dissolved Oxygen 

Concentration on the Distribution of Juvenile Suckers within the Williamson River Delta, 

Upper Klamath Lake, Oregon. Klamath Basin Science Conference. Medford, Oregon, 

February 3 2010. 

Bottcher, J., and S. Burdick. 2010. Age-1 Lost River and Shortnose Sucker Distribution, Habitat 

Use, and Apparent Movement in Upper Klamath Lake, Oregon. Klamath Basin Science 

Conference. Medford, Oregon, February 3 2010. 

Hendrixson, H.A., T. M. Wood, C. Erdman, C. Ellsworth, S. Burdick, D. Markle, N.L. Buccola. 

2010. Modeling larval sucker transport through the Williamson River Delta, Upper Klamath 

Lake, Oregon. Klamath Basin Science Conference. Medford, Oregon, February 3 2010. 
Publishing support provided by the U.S. Geological Survey

Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the 

Director, Western Fisheries Research Center

U.S. Geological Survey

6505 NE 65th Street

Seattle, WA 98115

http://wfrc.usgs.gov/
Burdick—Young-of-Year Lost River and Shortnose Suckers, Williamson River Delta Restoration Project and Upper Klamath Lake, Oregon, 2008–10—Final Report—Open-File Report 2012–1098