Validation of a Critical Assumption of the Riparian 

Habitat Hypothesis for White Sturgeon

Scientific Investigations Report 2006–5225

U.S. Department of the Interior

U.S. Geological Survey
Cover: Seasonally inundated riparian habitat downstream of Bonneville Dam at the head of Ives 

Island near North Bonneville, Washington.

(Photograph by Corey D. Wright, U.S. Geological Survey, June 2005.)
Validation of a Critical Assumption of the 

Riparian Habitat Hypothesis for 

White Sturgeon

B.K. van der Leeuw, M.J. Parsley, C.D. Wright, and E.E. Kofoot

Scientific Investigations Report 2006–5225

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers Director

U.S. Geological Survey, Reston, Virginia: 2006

For product and ordering information:

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS

For more information on the USGS--the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment:

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS

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 materials contained within this report.

Suggested citation:

van der Leeuw, B.K., Parsley, M.J., Wright, C.D., and Kofoot, E.E., 2006, Validation of a critical assumption of the 

riparian habitat hypothesis for white sturgeon: U.S. Geological Survey Scientific Investigations Report 2006-5225, 

20 p.
iii

Contents

Abstract...........................................................................................................................................................1

Background and Objectives.........................................................................................................................1

Study Site ........................................................................................................................................................2

Methods...........................................................................................................................................................3

Terminology of Early Life Stages ........................................................................................................3

White Sturgeon Early Life Stage Sampling ......................................................................................4

River Environment.................................................................................................................................4

Embryo, Free Embryo, and Larva Staging.........................................................................................4

Substrate Characterization .................................................................................................................6

Results .............................................................................................................................................................7

Sampling Gears.....................................................................................................................................7

White Sturgeon Embryos.....................................................................................................................7

White Sturgeon Free Embryos and Larvae.......................................................................................8

Substrate Characterization .................................................................................................................8

Discussion.......................................................................................................................................................9

Potential for Dewatering Early Life Stages ......................................................................................9

Acknowledgments.......................................................................................................................................12

References....................................................................................................................................................12

Appendixes ...................................................................................................................................................15
iv

Figures

Figure 1. Photograph of aerial view of the study site on the Columbia River, Oregon

and Washington ........................................................................... 2

Figure 2. Photograph of study site, sampling areas, and collection gear types,

Columbia River, Oregon and Washington ................................................ 3

Figure 3. Photographs of sampling with kick nets at the head of Ives Island,

downstream of Bonneville Dam............................................................ 5

Figure 4. Photographs of sampling frame laid over substrates during August 2005 at

Ives Island .................................................................................... 6

Figure 5. Photograph of artificial substrates sites where white sturgeon embryos

were collected, Columbia River near Ives and Pierce Islands ........................ 7

Figure 6. Photograph of capture sites where white sturgeon free embryos and larva

were collected, Columbia River at Ives Island .......................................... 9

Figure 7. Graph showing water elevation at Ives Island and river discharge at the

Bonneville Dam tailrace measured during the June 2005 sampling period ......... 10

Figure 8. Graph showing water elevation changes at Ives Island and depths at free

embryo and larvae capture sites ......................................................... 12

Tables

Table 1. Collection gears and effort of each gear used for the capture of white

sturgeon embryos, free embryos, and larvae in the Columbia River near Ives

and Pierce Islands........................................................................... 3

Table 2. White sturgeon embryos collected in the Columbia River near Ives and

Pierce Islands .............................................................................. 8

Table 3. Collection data and water elevations associated with embryos collected on

artificial substrates set in less than 1.5 meters of water near Ives Island............ 11

Table 4. Capture data and Ives Island water elevations associated with free embryo

and larval white sturgeon captured near Ives Island ................................. 11
Conversion Factors and Datums

Conversion Factors

Multiply By To obtain

centimeter (cm) 0.3937 inch (in.)

cubic foot per second (ft3/s) 0.0283 cubic meter per second (m3/s)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

liter (L) 33.82 ounce, fluid (fl. oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

meter per second (m/s) 3.281 foot per second (ft/s) 

kilogram (kg) 2.205 pound avoirdupois (lb)

thousand cubic feet per second (k×ft3/s) 0.0283 one thousand cubic meters per second (k×m3/s)

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 World Geodetic System 1984 Datum 

(WGS 84). 

Map projection format is Universal Transverse Mercator (UTM) Universal Polar Stereographic 

(UPS). 

Universal Transverse Mercator (UTM) Zone is 10 North.
vi

This page is intentionally blank.
Abstract

In June 2005, we confirmed that white sturgeon 

Acipenser transmontanus embryos, free embryos, and larvae 

could be found in shallow seasonally flooded riparian habitat 

in the Columbia River downstream of Bonneville Dam. This 

validates a critical assumption of the Coutant Riparian Habitat 

Hypothesis that during white sturgeon spawning, embryos 

are either deposited in, or transported to, seasonally flooded 

riparian habitat.

Sampling for early life stages of white sturgeon took 

place in the vicinity of Ives and Pierce islands using eight 

types of collection gear. A total of 1,372.9 hours of sampling 

was completed with 254 embryos, 6 free embryos, and 1 larva 

collected.

Surface substrates were characterized in August 2005 

for 9 of the 21 sites where embryos, free embryos, and 

larvae were found. The sites characterized were composed of 

0.35 percent fines, 53.56 percent gravel, 45.69 percent cobble, 

and 0.41 percent boulder.

Background and Objectives

White sturgeon populations vary considerably in 

abundance and age structure throughout the Columbia River 

Basin (Beamesderfer and others, 1995). The construction of a 

series of hydroelectric dams on the Columbia and Snake rivers 

has created functionally discreet populations of white sturgeon 

within the basin (North and others, 1993). The abundance 

and density of white sturgeon is greatest in the unimpounded 

river downstream of Bonneville Dam. This area supports one 

of the largest and most productive sturgeon populations in the 

world (DeVore and others, 1995). Conversely, the geologically 

isolated white sturgeon population from the Kootenai River 

has been listed as endangered since 1994. White sturgeon 

populations in the Snake River downstream from Hells 

Canyon Dam appear to be persisting, but at a lower abundance 

than prior to impoundment.

Prior to Coutant’s (2004) promotion of the Riparian 

Habitat Hypothesis, variations in population status among 

areas had been attributed to a number of factors. In particular, 

construction and operation of hydroelectric dams on the 

Columbia and Snake rivers have directly affected white 

sturgeon populations in several ways. For example, fish cannot 

migrate up and down the river as they historically did (North 

and others, 1993), and areas of spawning habitat have been 

reduced (Parsley and Beckman 1994). Variations in population 

characteristics also have been attributed to differences in 

exploitation rates and recruitment success, access to marine 

food resources, and suitability of hydrologic conditions and 

available habitats (Beamesderfer and others, 1995; DeVore and 

others, 1995).

Coutant (2004) developed a hypothesis to explain 

variability in spawning success among white sturgeon 

populations. A critical assumption of the hypothesis is that 

white sturgeon embryos are either deposited in or transported 

to shallow seasonally flooded riparian habitat and adhere to 

newly wetted rocks and vegetation during incubation. He 

proposed that newly hatched free embryos (eleutheroembryos) 

remain in these shallow waters, hiding in crevices for 

protection from predation. When free embryos transition 

to exogenous feeding larvae, this riparian habitat would 

theoretically offer plentiful food. When water recedes with 

decreasing discharge, juvenile sturgeon would also retreat 

to deeper channels. This hypothesis is supported by findings 

from the unregulated lower Fraser River where white sturgeon 

embryos and larvae were collected in island complexes and 

side channels but not in the main channel (Perrin and others, 

2003).

It is generally accepted that white sturgeon embryos 

and larvae can be found on the riverbed substrate in various 

water depths and habitats downstream of dams (Parsley and 

others, 1993; McCabe and Tracy 1994). Previous work in 

the Columbia River primarily investigated the timing and 

general location of white sturgeon spawning and did not 

focus on the occurrence of embryos or larvae in shallow 

riparian habitats. Parsley and others, (1993) and McCabe 

and Tracy (1994) collected embryos in depths of 4–27 m 

and 3–23 m, respectively. Accurate information concerning 

the spatial distribution of embryos and larvae downstream of 

hydroelectric dams is critical in assessing how construction 

and operation of dams may affect survival of early life stages 

of sturgeon.

Validation of a Critical Assumption of the Riparian Habitat 

Hypothesis for White Sturgeon

By Bjorn K. van der Leeuw, Michael J. Parsley, Corey D. Wright, and Eric E. Kofoot
If white sturgeon early life stages do occur in shallow 

riparian habitats, construction and operation of the federal 

hydropower system may affect survival and subsequent 

recruitment to age-1. In shallow areas, they could be 

susceptible to desiccation due to short-term fluctuations in 

water elevations resulting from daily dam operations. These 

short-term fluctuations are known to strand outmigrating 

anadromous salmonids (Tiffan and others, 2002) during the 

same time that white sturgeon are known to spawn, incubate, 

and hatch. The dampening of the seasonal river discharge by 

dams to reduce flooding and increase power generation in 

winter has also reduced the seasonal water level fluctuations in 

areas where backwater effects are minimal, and thus reduced 

availability of newly inundated riparian habitats. Further, 

white sturgeon populations as a whole may suffer from a loss 

of productivity due to the extensive loss of riparian habitat 

caused by impoundment and stabilization of water levels 

within reservoirs.

Objectives of this study were to (1) determine if 

white sturgeon embryos, free embryos, and larvae occur in 

seasonally inundated riparian habitats, and (2) characterize 

surface substrates at sites where embryos, free embryos, and 

larvae were found.

Study Site

Sampling was done in the Columbia River about four 

river kilometers (rkm) downstream of Bonneville Dam. All 

collection efforts were made near Pierce and Ives Islands 

(fig. 1), at rkm 228.5 and 229.3, respectively.

The Columbia River downstream of Bonneville Dam 

is recognized as good white sturgeon spawning habitat, with 

successful recruitment to age-0 occurring each year. White 

sturgeon embryos are found in the first 11 km downstream of 

Bonneville Dam during spawning season (McCabe and Tracy, 

1994). In the lower Columbia River, spawning occurs when 

water temperatures range from 10 to 18°C (Parsley and others, 

1993).

The Columbia River immediately downstream of 

Bonneville Dam is highly regulated by discharge of the dam. 

Water surface elevations at Ives and Pierce Islands closely 

follow the amount of discharge from Bonneville Dam with 

minimal (< 0.3 m) tidal influence. The flow in the side channel 

that runs between the islands and the Washington shore is only 

slightly affected by the inflow of Hamilton and Hardy Creeks.

Hamilton Creek

Washington

Oregon

Bonneville

Dam

Ives Island

Pierce Island

Flow

Figure 1. Aerial view of the study site on the Columbia River, Oregon and Washington.

 Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Methods

Terminology of Early Life Stages

We used the terms embryo, free embryo, and larva to 

describe white sturgeon early life stages detected during 

sampling. These terms are adapted from Balon (1975, 1984).

The term embryo is used to define the life period that 

begins at fertilization and ends at hatch. White sturgeon 

embryos gain nutrition endogenously. The free embryo period 

begins when an embryo hatches from its egg casing. At this 

stage sturgeon still receive all nutrition endogenously from a 

yolk sac. This period ends with the transition to exogenous 

feeding. The larval period for sturgeon begins with the start 

of exogenous feeding and ends when fins and organs are fully 

formed.

Eight types of collection gear were used to sample for 

embryos, free embryos, and larvae (table 1). Two gears, 

artificial substrates and plankton nets, are commonly used 

to collect early life stages of white sturgeon. In addition to 

these gears we used kick nets, suction devices, and a view 

scope to search for embryos, free embryos, and larvae among 

rock crevices and in vegetation where artificial substrates and 

plankton nets have not been used.

Collection efforts were made in various areas including 

the main channel of the Columbia River, the shallows on 

the main channel side of the islands, the shallows along the 

Oregon shore, and the side channel that runs between the 

islands and the Washington shore. The federal navigation 

channel was not sampled due to a high volume of commercial 

and recreational boat traffic. Figure 2 shows an overview of 

areas sampled.

Gear Effort 

(hours)

Stage collected

Embryo Free embryo Larvae

Artificial substrate 1,273.45 254 0 0

Plankton net

 Boat D-shaped 2.75 0 0 0

 Staked D-shaped 46.53 0 0 1

 Staked square 25.60 0 0 0

Bilge pump .83 0 0 0

Kick net 22.42 0 6 0

Slurp gun .58 0 0 0

View scope .75 0 0 0

Table 1. Collection gears and effort of each gear used for the 

capture of white sturgeon embryos, free embryos, and larvae in 

the Columbia River near Ives and Pierce Islands.

Figure 2. Study site, sampling areas, and collection gear types, Columbia River, Oregon and Washington.

ARTIFICIAL SUBSTRATES

KICK NETS

PLANKTON NETS

0 250 500 750 1,000 Meters

WASHINGTON

PIERCE ISLAND

IVES ISLAND

OREGON

Flow

Main Channel

Side Channel

Methods 
White Sturgeon Early Life Stage Sampling

Artificial substrates based on McCabe and Beckman 

(1990) were deployed and retrieved from a 4.9-m aluminum 

johnboat. Individual 76 × 91-cm artificial substrates were 

placed on the river bottom parallel to the river current. Each 

artificial substrate was set individually with one claw anchor 

and a set of surface floats. A Global Positioning System 

(ETrex Legend®, Garmin International, Inc., Olathe, Kans.) 

waypoint was taken for the location of each artificial substrate. 

The water depth at the time of deployment was recorded for 

each substrate using the boat’s depth sounder. After retrieval, 

artificial substrates were inspected visually and any embryos 

present were removed using forceps.

A 25 × 46-cm rectangular frame kick net (Watermark 

bottom aquatic kick net, Forestry Suppliers, Inc., Jackson, 

Miss.) with 500-micron mesh was used to sample for embryos, 

free embryos, and larvae in wadeable water. Kick net sampling 

was done by placing the long axis of the frame of the kick 

net on the substrate perpendicular to the river bottom. The 

substrate would then be disturbed directly upstream from the 

kick net (fig. 3). The nets also were repeatedly swept through 

inundated vegetation.

Plankton nets were used extensively during this study. 

Plankton nets were mounted in three configurations to sample 

both wadeable and non-wadeable water. Plankton nets were 

mounted on two differently shaped frames, D-shaped and 

square. The D-shaped net was fished with the flat side of the 

‘D’ in contact with the river bottom. It measured 75 cm at 

its widest point and a maximum of 53 cm in height. The Dshaped plankton net was constructed of 2-mm knotless mesh. 

The square plankton net had a 50 × 50-cm frame with 500-

micron mesh.

Wadeable water was sampled using D-shaped and squareframed plankton nets. The nets were staked into the substrate 

so the bottom of the frame was in contact with the substrate 

and the frame was perpendicular to the river bottom. Plankton 

nets were fished for variable time increments. Once staked 

into the substrate, plankton nets were visually monitored to 

assure they were fishing properly. After about 30 minutes of 

sampling, the collection cup of the plankton net was removed 

and the contents were poured into a 0.95-L glass jar. The 

collection cup was then reattached and the net was redeployed 

to continue sampling. The contents of the jar were visually 

inspected for the presence of white sturgeon embryos, free 

embryos, and larvae.

Non-wadeable water was sampled with D-shaped 

plankton nets. Two D-shaped plankton nets were 

simultaneously deployed from a 7.6-m aluminum boat 

anchored in the current. Each plankton net was weighted with 

two 9-kg lead balls on the bottom of the frame to facilitate the 

net reaching the substrate and being held in an upright position 

in the strong currents. The plankton nets were retrieved and 

checked after each one-half hour of sampling. The collection 

cup of the plankton net was removed and the sample was 

visually inspected for embryos, free embryos, and larvae.

Three gears were used less than one hour each and 

were minor components of the study. A manual bilge pump 

(Thirsty-mate® Hand Pump; West Marine, Watsonville, Calif.) 

was used to suction the interstitial spaces of the substrate. A 

slurp gun (Rick’s Tackle, Long Beach, Calif.) was used in a 

similar manner as the bilge pump. A view scope (Aqua Scope 

IITM; Lawrence Enterprises, Seal Harbor, Maine) was used to 

observe submerged vegetation for attached embryos.

Due to the various gears used, effort was measured 

in hours. The measurement of effort in hours acted as an 

estimation of effort and a relative comparison of use among 

gears, but was not an attempt to compare the effectiveness of 

gears or quantify the amount of habitat sampled.

River Environment

Data pertaining to river environment were collected 

from multiple sources. Elevation and flow data for Bonneville 

tailrace and Ives Island were taken from the Fish Passage 

Center website (Fish Passage Center, 2005). Temperature data 

for Ives Island was also obtained from the Fish Passage Center 

website (Fish Passage Center, 2005). The gage recording 

the Ives Island data was near the upriver terminus of the 

channel on the north side of Ives Island. Temperature data for 

the Bonneville tailrace were from the Columbia River Data 

Access in Real Time website (Columbia River Data Access in 

Real Time, 2005). Bonneville tailrace data were collected by a 

water-quality monitoring station near Cascade Island directly 

on the downstream side of the Bonneville Dam.

River environment data were collected during field 

sampling of all free embryo and larva capture sites. Depth was 

recorded using a top set wading rod (Swoffer Instruments, 

Inc., Seattle, Wash.). Temperature data were collected using 

a YSI handheld water-quality meter (Model 85D, YSI, Inc., 

Yellow Springs, Ohio) Velocity measurements were made 

with a Swoffer direct reading current velocity meter (Model 

2200, Swoffer Instruments, Inc., Seattle, Wash.) attached to a 

Price AA bucket wheel. Six velocity readings were taken over 

a one-minute period and then averaged to obtain a composite 

velocity for each capture site.

Embryo, Free Embryo, and Larva Staging

Embryos, free embryos, and larvae captured during field 

sampling were immediately placed in sample vials containing 

95 percent ethanol. After about one month, the alcohol was 

removed from the samples and replaced with a 10 percent 

solution of formalin. After a minimum one-month fixation 

in formalin the samples were drained and then filled with 

70 percent ethanol. During the process of switching mediums 

of preservation, the sample vials were filled with distilled 

water for 10 minutes and then drained to remove any latent 

residues.

 Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Figure 3. Sampling with kick nets at the head of Ives Island, downstream of Bonneville Dam. Flooded vegetation is predominantly 

Pacific willow Salix lasiandra. Photographs show the type of habitat where free embryos were collected.

Methods 
Embryos, free embryos, and larvae 

were inspected using a dissecting 

microscope. Each embryo was assigned 

a numbered stage of development based 

on Beer (1981). Free embryos and larvae 

were assigned a stage of development in 

days post-hatch based on Beer (1981).

Substrate Characterization

During August 2005, riverbed 

substrates were characterized at sites 

where embryos, free embryos, and larvae 

were collected. Grid counts (Bunte and 

Abt, 2001) were used to sample surface 

substrates for characterization. A 120 

× 120-cm portable sampling frame was 

used to randomly select substrate particles 

for measurement. Substrate particles 

that were directly underneath each 

intersection of the grid were measured 

using a gravelometer. The grid spacing 

of the sampling frame was 13.2 cm. 

The sampling frame grid contained 64 

intersections (fig. 4).

A Global Positioning System receiver 

was used to navigate to the sites in which 

early life stages were captured during the 

June sampling period. At each site the 

portable sampling frame was laid upon the 

substrate. At each site, 128–137 (mean = 

130) substrate particles were measured, 

therefore, the sampling frame had to be 

placed a minimum of twice at each site. 

When a particle was large enough to be 

contacted by two intersections of the 

sampling grid it was measured only once. 

In this case, the sampling frame would 

be laid down a third time to make up for 

particles that could be measured only once 

because they were touched by two grids. 

When it was necessary to lay the sampling 

frame down a third time, a random 

number from 1 to 8 was chosen along 

with a random side from which to start 

the measurements. This random number 

combination would determine from which 

transect of the grid the particles would be 

measured.

A. Site 47. Larval capture site

B. Site 18. Embryo capture site

Figure 4. Sampling frame laid over substrates during August 2005 at Ives Island. 

A US SAH-97 hand-held particle size analyzer (commonly known as a gravelometer) was used to measure the b-axis of 

each particle. The US SAH-97 has 14 square holes that range from 2 to 180 mm. Particles greater than 180 mm were measured 

with a ruler built into the side of the gravelometer. Each substrate particle measured was put into one of 16 size classes. The 

smallest classification for a particle-size class is fines (< 2 mm) and the largest is boulder (≥ 256 mm). Each particle was 

measured individually based on which hole it could fit through in the gravelometer. Particles were tallied to create a size class 

percentage frequency of each sample. A complete guide for using the US SAH-97 particle-size analyzer is outlined in Potyondy 

and Bunte (2002).

 Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Results

Sampling Gears

Three of the eight sampling gears collected white 

sturgeon embryos, free embryos, or larvae (table 1). Artificial 

substrates were successful in collecting white sturgeon 

embryos. They were fished for a total of 1,273.45 hours. Kick 

nets were used for 22.42 hours and were effective in capturing 

white sturgeon free embryos. One larva was collected during 

the 46.53 hours that staked D-shaped plankton nets were 

fished.

The bilge pump, slurp gun, and the view scope were all 

used less than one hour and did not collect early life stages of 

sturgeon. D-shaped plankton nets deployed from a boat were 

fished 2.75 hours and did not capture embryos or larvae except 

for one fungus-covered sturgeon embryo that was not counted 

in the total. Square-shaped plankton nets that were staked into 

the substrate were fished for 25.60 hours and did not capture 

embryos or larvae.

White Sturgeon Embryos

All white sturgeon embryos detected during field 

sampling were collected on artificial substrates. A total of 

254 viable embryos were collected. An additional 23 dead or 

damaged embryos were collected, but were not included in the 

total.

Samples were collected with artificial substrates during 

June 6-10 and 13-17, 2005. Artificial substrates were not set 

during the weekend of June 11-12, 2005, due to increased 

recreational boat traffic. A total of 33 sets were completed 

accounting for 1,273.45 hours of effort. Artificial substrates 

had a mean soak time of 38 hours and 35 minutes (range 

22:20–48:30). White sturgeon embryos were collected in 17 

of 33 artificial substrate sets (fig. 5), whereas 15 sets resulted 

in no catch of sturgeon embryos and one set captured only two 

dead embryos. Appendix 1 lists all embryo capture sites.

The average set depth of the 17 artificial substrates that 

captured embryos was 2.15 m (range = 0.61–3.35), however 

variations in river discharge continuously altered depths. 

77

76

38

34

21 19

18

17

16

15

8

7

3

2

33

6

1

EMBRYO CAPTURE SITE AND

SITE IDENTIFICATION NO.

18

IVES ISLAND

PIERCE ISLAND Flow

Side Channel

Main Channel

0 100 200 300 400 Meters

Figure 5. Artificial substrates sites where white sturgeon embryos were collected, Columbia River near Ives and Pierce Islands.

Results 
The mean water temperature during the sampling period of 

artificial substrates, as measured downstream of Bonneville 

Dam at Cascade Island (Columbia River Data Access in Real 

Time, 2005), was 15.9°C (range = 15.4–16.4°C).

Based on embryological development stages outlined in 

Beer (1981) we collected embryos that were from stage two 

(changing pigmentation) to stage 13 (early neurulation). Stage 

one (unfertilized) eggs were not captured during sampling. An 

additional four stages occur after early neurulation and prior to 

hatching, but we did not detect any embryos from these stages. 

The most prevalent stage collected was stage six (fourth 

through sixth cleavage), with 78 of the 254 embryos from 

this stage. Table 2 presents a complete outline of embryos 

collected and staged during this study. 

White Sturgeon Free Embryos and Larvae

The presence of white sturgeon free embryos and larvae 

in shallow wadeable habitat was confirmed near Ives Island 

downstream of Bonneville Dam. Six 0-1 day post-hatch free 

embryos were captured on June 8-9, 2005, using kick nets at 

sites 22, 31, and 32 at the head of Ives Island (fig. 6). Free 

embryos at this stage are in “hiding phase” (Brannon and 

others, 1985) exemplified by low mobility due to the presence 

of a large yolk sac and the lack of developed fins. The free

embryos were detected at water depths of 0.31–0.70 m within 

the interstitial spaces among the cobble/gravel substrate that is 

the dominant riverbed matrix of the nearshore environment of 

Ives Island. The temperature range was 15.9 to 16.0°C at the 

time of capture for free embryos. Composite velocities of 1.38, 

2.50, and 1.50 m/s were measured at free embryo capture sites 

22, 31, and 32, respectively.

One white sturgeon larva was captured (site 47; fig. 6) 

in a water depth of 0.59 m on June 14, 2005, in a D-shaped 

plankton net anchored to the substrate. This larva was 

estimated to be 10 days post-hatch and would have been 

exogenously feeding. The temperature at the capture site was 

16.7°C. A composite velocity of 0.88 m/s was measured at 

the capture site. Appendix 1 lists all free embryo and larval 

capture locations.

Substrate Characterization

In August 2005, substrate composition characterization 

was completed for some of the sites where white sturgeon 

early life stages were captured. Substrate sampling in August, 

after water levels dropped, allowed easy access to many sites 

that would have been difficult to sample during the high flows 

of June. However 12 sites were still too deep to be effectively 

sampled by wading with a sampling frame. Grab samplers 

were considered, but cobbles and boulders would make such 

sampling devices ineffective.

Substrates were characterized at 9 sites, including 5 of 

the 17 sites where at least one white sturgeon embryo was 

collected and all 4 sites where free embryos and larvae were 

captured. The combined percentage frequency averages for all 

9 sites characterized were: 0.35 percent fines, 53.56 percent 

gravel, 45.69 percent cobble, and 0.41 percent boulder. The 

combined percentage frequency averages for the five embryo 

sites characterized were: 0.00 percent fines, 52.88 percent 

gravel, 46.39 percent cobble, and 0.73 percent boulder. The 

combined percentage frequency averages for the three free 

embryo and one larva sites characterized were: 0.78 percent 

fines, 54.40 percent gravel, 44.82 percent cobble, and 

0.00 percent boulder. Detailed information about each site 

is presented in Appendix 2. Data and plots for substrates are 

based on methods outlined in Potyondy and Bunte (2002).

Stage Stage name No. of eggs

1 Unfertilized egg 0

2 Changing pigmentation 55

3 First cleavage 3

4 Second cleavage 6

5 Third cleavage 13

6 Fourth through sixth cleavage 78

7 Late cleavage 38

8 Early epithelial 17

9 Late epithelial 10

10 Involution 22

11 Large yolk plug 51

12 Small yolk plug 1

13 Early neurulation 10

Mort Damaged or dead embryo 23

Table 2. White sturgeon embryos collected in the Columbia River 

near Ives and Pierce Islands.

[Numbers represent embryos collected at all sites combined. Embryos are 

divided into stages based on Beer (1981)]

 Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Discussion

Through field sampling we proved that white sturgeon 

embryos, free embryos, and larvae are present in shallow water 

adjacent to spawning areas, confirming a critical assumption 

of the Coutant (2004) Riparian Habitat Hypothesis. While we 

did not attempt to test the hypothesis itself—that the presence 

of riparian habitat is critical to the success of white sturgeon 

populations—we did prove that some proportion of the eggs, 

free embryos, and larvae can be found in inundated riparian 

habitats. The high water velocities characteristic of this white 

sturgeon spawning area are likely to disperse embryos and free 

embryos throughout the river channel, with some ultimately 

settling near the shoreline in shallow water. The free embryos 

detected by kick netting at the head of Ives Island were able to 

enter interstitial spaces among the gravels and cobbles to keep 

from being washed further downstream.

WFRC19-0063_06

31

47

32 22

LARVA CAPTURE SITE AND

 SITE IDENTIFICATION NO.

FREE EMBRYO CAPTURE SITE

 AND SITE IDENTIFICATION NO.

47

22

IVES ISLAND

PIERCE ISLAND

Flow

Side Channel

Main Channel

0 100 200 300 400 Meters

Figure 6. Capture sites where white sturgeon free embryos and larva were collected, Columbia River at Ives Island.

Potential for Dewatering Early Life Stages

These findings raise concerns that water level fluctuations 

caused by load-following operations at Bonneville Dam or 

other hydropower system related operations could dewater 

these early life stages. Water-surface elevation gages at 

Bonneville Dam and near Ives Island (Fish Passage Center, 

2005; Columbia River Data Access in Real-Time, 2005) reveal 

that water elevations in this area can decrease more than 1 m 

during a 24-hour period (fig. 7).

Embryos that adhere to the substrate in shallow areas will 

incubate about 4–10 days before hatching. Thus, the potential 

for dewatering is related to the original depth at which the 

embryos attach as well as seasonal and short-term cyclical 

fluctuations in water levels. If embryos happen to attach to the 

riverbed during a period of daily cyclical high water elevation, 

the risk for dewatering increases, particularly if the seasonal 

hydrograph is declining. However, if embryos adhere to the 

Discussion 
riverbed during the ascending limb of a seasonal hydrograph, 

the water depth over the incubation site may continue to 

increase despite daily fluctuations in water surface elevation 

caused by tides or hydropower operations.

In this study, embryos were collected on five artificial 

substrates that were set in less than 1.5 m of water. The 

potential for dewatering at these capture locations was 

evaluated by assessing the difference in water elevations 

between the set time of the artificial substrates and an estimate 

of when the embryos would have hatched. According to 

Deng and others (2002), white sturgeon embryos hatch in 

about 7 days at water temperatures of 16°C. Table 3 shows 

that although none of the locations sampled were dewatered 

during the embryo incubation period, water depth at two sites 

dropped to less than 0.17 m. Embryos in very shallow water 

may be exposed to fluctuating water temperatures and reduced 

water velocities may deprive eggs of oxygen, increase the 

chance of fungal growth, and increase risk of predation. After 

hatch, white sturgeon free embryos are dispersed by the river 

currents before settling to the river bottom. After absorbing 

their yolk sac, they emerge from the interstitial spaces of the 

substrate and disperse downstream as larvae. In this study, free 

embryos and the single larva captured were found in areas 

where the water depths were 0.31–0.70 m. These areas were 

shallower than areas where embryos were collected. Thus, 

these older stages may be more susceptible to dewatering. 

WFRC19-0063_Fig.07

6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

JUNE 2005

50

100

150

200

250

DISCHARGE, IN THOUSAND CUBIC FEET PER SECOND

3.5

4.0

4.5

5.0

5.5

6.0

ELEVATION, IN METERS

IVES ISLAND ELEVATION, IN METERS

BONNEVILLE FLOW, IN THOUSAND CUBIC FEET PER SECOND

0

Figure 7. Water elevation at Ives Island and river discharge at the Bonneville Dam tailrace measured during 

the June 2005 sampling period. Discharge is reported in cubic feet per second x 1,000 (ft3/s) for consistency with 

common reporting of Columbia River flows.

10 Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Collection Ives Island water elevation (meters) Depth (meters)

Site Set date Set time Collection Minimum Difference Collection Minimum

8 06-07-2005 11:20 4.40 4.00 0.40 0.91 0.51

18 06-08-2005 12:09 4.37 3.89 .48 .61 .13

21 06-08-2005 13:32 4.35 3.88 .47 1.22 .75

33 06-13-2005 10:16 4.06 3.61 .45 .61 .16

34 06-13-2005 10:28 4.06 3.61 .45 .91 .46

Table 3. Collection data and water elevations associated with embryos collected on artificial substrates set in 

less than 1.5 meters of water near Ives Island.

[Ives Island water elevation: Collection, water elevation at the time an artificial substrate was set; Minimum, minimum water 

elevation recorded within 168 hours (7 days) post set time; Difference, difference between collection elevation and minimum 

elevation. Depth: Collection, water depth in which artificial substrate was set; Minimum, water depth embryo would be exposed to at 

minimum water elevation]

Table 4 shows that the site where the single larva was captured 

was dewatered within 24 hours and that the water depth at 

another site where a free embryo was captured dropped to 

0.06 m. Figure 8 shows that all sites where free embryos and 

the larva were captured were dewatered for short periods 

within days. Since these early life stages are more mobile than 

the adhesive embryos, they may be able to avoid dewatering 

by moving to deeper areas or by remaining within interstitial 

spaces among gravels and cobbles that retain water.

The sampling we conducted specifically targeted 

near shore habitats. Research has not been undertaken to 

systematically sample all depths downstream of a white 

sturgeon spawning area to describe the spatial distribution of 

spawned embryos within the river channel. Further research 

should be done to determine the distribution of white sturgeon 

early life stages throughout the river channel to characterize 

the role of permanently wetted versus seasonally inundated 

habitats.

Laboratory studies should be performed to test the 

ability of white sturgeon embryos, free embryos, and larvae 

to withstand dewatering. If white sturgeon embryos, free 

embryos, and larvae are regularly present in shallow water 

habitat, it can be reasoned that water level fluctuations due 

to load following at hydroelectric dams may have an adverse 

effect on the growth and survival of these early life stages. 

Experiments should investigate the influence of duration of 

dewatering and effects of fluctuating water temperatures on 

survival and growth of young fish.

Stage

Capture Ives Island water elevation (meters) Depth (meters)

Site Date Time Capture Minimum Difference Capture Minimum

Free embryo (4) 22 06-08-2005 14:25 4.36 4.29 0.07 0.31 0.24

Free embryo (1) 31 06-09-2005 13:07 4.86 4.55 .31 .70 .39

Free embryo (1) 32 06-09-2005 13:07 4.86 4.55 .31 .37 .06

Larva (1) 47 06-14-2005 13:25 4.57 3.88 .69 .59 -.10

Table 4. Capture data and Ives Island water elevations associated with free embryo and larval white sturgeon captured near 

Ives Island.

[Stage: numbers of specimens of each stage collected are in parentheses. Ives Island water elevation: Capture, water elevation at time of capture; 

Minimum, minimum water elevation recorded within 24 hours post-capture; Difference, maximum decrease in water elevation within 24 hours postcapture. Depth: Capture, water depth measured at time of capture; Minimum, water depth at each site within 24 hours post-capture]

Discussion 11
Acknowledgments

Funding for this work was provided by the Columbia 

River Research Laboratory. Charles Berenbrock provided the 

gravelometer we used to measure particle sizes. We thank 

Charles Coutant and Vaughn Paragamian for their comments 

on this report.

 References

Balon, E.K., 1975, Terminology of intervals in fish 

development: Journal of the Fisheries Research Board of 

Canada, v. 32, no. 9, p. 1663-1670.

Balon, E.K., 1984, Reflections on some decisive events in the 

early life of fishes: Transactions of the American Fisheries 

Society, v. 113, Issue 2, p. 178-185.

6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

JUNE 2005

3.5

4.0

4.5

5.0

5.5

ELEVATION, IN METERS

Site 32

Free embryo captured

in a depth of 0.37 meters

Site 31

Free embryo captured

in a depth of 0.70 meters

Site 47

Larva captured

in a depth of 0.59 meters

Site 22

4 free embryos captured

in a depth of 0.31 meters

WFRC19-0063_Fig.08

Figure 8. Water elevation changes at Ives Island and depths at free embryo and larvae capture sites. Horizontal dashed 

lines indicate minimum water surface elevations needed to maintain water over capture sites. All sites were dewatered 

for short periods after free embryos or larvae were captured. Site 47 was dewatered less than 24 hours after one larva 

was captured there.

Beamesderfer, R.C.P., Rien, T.A., and Nigro, A.A., 1995, 

Differences in the dynamics and potential production of 

impounded and unimpounded white sturgeon populations 

in the lower Columbia River: Transactions of the American 

Fisheries Society, v. 124, Issue 6, p. 857-872.

Beer, K.E., 1981, Embryonic and larval development of white 

sturgeon (Acipenser transmontanus): Davis, University of 

California, Master’s thesis, 93 p.

Brannon, E., Brewer, S., Setter, A., Miller, M., Utter, F., and 

Hershberger, W., 1985, Columbia River white sturgeon 

(Acipenser transmontanus) early life history and genetics 

study: Seattle, University of Washington and U.S. National 

Marine Fisheries Service, Final Report to the Bonneville 

Power Administration (Project 83-316), 68 p.

Bunte, K., and Abt, S.R., 2001, Sampling surface and 

subsurface particle-size distributions in wadeable graveland cobble-bed streams for analyses in sediment transport, 

hydraulics, and streambed monitoring: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research 

Station, Fort Collins, Colo., General Techical Report 

RMRS-GTR-74, 428 p.

12  Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Columbia River Data Access in Real Time, 2005, River 

environment, Cascade Island temperature: Columbia River 

data available on the Web, accessed January 2006 at http://

www.cbr.washington.edu/dart/river.html

Coutant, C.C., 2004, A riparian habitat hypothesis for 

successful reproduction of white sturgeon: Reviews in 

Fisheries Science, v. 12, no. 1, p. 23-73.

Deng, X., Van Eenennaam, J.P., and Doroshov, S.I., 2002, 

Comparison of early life stages and growth of green and 

white sturgeon: American Fisheries Society Symposium 

v. 28, p. 237-248.

DeVore, J.D., James, B.W., Tracy, C.A., and Hale, D.A., 1995, 

Dynamics and potential production of white sturgeon in the 

unimpounded lower Columbia River: Transactions of the 

American Fisheries Society, v. 124, Issue 6, p. 845-856.

Fish Passage Center, 2005, Ives Island real-time water 

temperature and water elevation: Fish Passage Center data 

available on the Web, accessed January 2006 at http://www.

fpc.org

McCabe, G.T., Jr., and Beckman, L.G., 1990, Use of an 

artificial substrate to collect white sturgeon eggs: California 

Fish and Game 76, v. 76, no. 4, p. 248-250.

McCabe, G.T., Jr., and Tracy, C.A., 1994, Spawning and early 

life history of white sturgeon, Acipenser transmontanus, in 

the lower Columbia River: U.S. Department of Commerce, 

NOAA NMFS Scientific Publication Office, Fishery 

Bulletin v. 92, no. 4, p. 760-772.

North, J.A., Beamesderfer, R.C., and Rien, T.A., 1993, 

Distribution and movements of white sturgeon in three 

lower Columbia reservoirs: Northwest Science. v. 67, no. 2, 

p. 105-111.

Parsley, M.J., Beckman, L.G., and McCabe, G.T., 1993, 

Spawning and rearing habitat use by white sturgeons in the 

Columbia downstream form McNary Dam: Transactions of 

the American Fisheries Society, v. 122, Issue 2, p. 217-227.

Parsley, M.J., and Beckman, L.G., 1994, White sturgeon 

spawning and rearing habitat in the lower Columbia River: 

North American Journal of Fisheries Management, v. 14, 

Issue 4, p. 812-827.

Perrin, C.J., Rempel, L.L., and Rosenau, M.L., 2003, White 

sturgeon spawning habitat in an unregulated river: Fraser 

River, Canada: Transactions of the American Fisheries 

Society, v. 132, issue 1, p. 154-165.

Potyondy J., and Bunte, K., 2002, Sampling with the 

US SAH-97 hand-held particle size analyzer: Federal 

Interagency Sedimentation Project, Waterways Experiment 

Station, Vicksburg, Miss., 6 p.

Tiffan, K.F., Garland, R.D., and Rondorf, D.W., 2002, 

Quantifying flow-dependent changes in subyearling fall 

Chinook salmon rearing habitat using two-dimensional 

spatially explicit modeling: North American Journal of 

Fisheries Management, v. 22, Issue 3, p. 713-726.

 References 13
This page is intentionally blank.

14  Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Site Latitude Longitude Life stage No. collected

Capture

Date Time

1 45.62258271 -121.9892485 Embryo 31 06-07-2005 09:55

2 45.62289954 -121.9889513 Embryo 5 06-07-2005 10:20

3 45.61771374 -121.0038865 Embryo 2 06-07-2005 11:35

6 45.62254046 -121.9891958 Embryo 1 06-08-2005 11:25

7 45.62241121 -121.9888307 Embryo 23 06-08-2005 11:00

8 45.62297238 -121.9890932 Embryo 1 06-08-2005 12:29

15 45.62257919 -121.9881090 Embryo 131 06-10-2005 09:20

16 45.62292762 -121.9880778 Embryo 8 06-10-2005 10:09

17 45.62313231 -121.9881475 Embryo 13 06-10-2005 10:23

18 45.62350572 -121.9881395 Embryo 2 06-10-2005 10:26

19 45.62229428 -121.9896724 Embryo 30 06-10-2005 10:50

21 45.62228238 -121.9908966 Embryo 1 06-10-2005 11:09

22 45.62495504 -121.9863766 Free embryo 4 06-08-2005 14:25

31 45.62489829 -121.9864324 Free embryo 1 06-09-2005 13:07

32 45.62493341 -121.9865616 Free embryo 1 06-09-2005 13:07

33 45.62611006 -121.9854349 Embryo 1 06-15-2005 09:30

34 45.62628692 -121.9849599 Embryo 1 06-15-2005 09:51

38 45.62157528 -121.9993039 Embryo 1 06-15-2005 11:23

47 45.62309953 -121.9894973 Larva 1 06-14-2005 13:25

76 45.61899584 -121.9999048 Embryo 2 06-17-2005 09:46

77 45.61831858 -122.0021020 Embryo 1 06-17-2005 10:24

Appendix 1. Geographic coordinates for white sturgeon early life stage collection sites.

[Map datum is WGS 84, UTM Zone 10N. Capture: for embryo sites: date/time an artificial substrate was retrieved; for free 

embryos and larvae: date/time collection gear was checked and the presence of white sturgeon noted]

Appendixes

Appendixes 15
Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 0 .00 .00

Very fine gravel <4.0 0 .00 .00

Fine gravel <5.6 0 .00 .00

Fine gravel <8.0 0 .00 .00

Medium gravel <11.3 1 .73 .73

Medium gravel <16.0 6 4.38 5.11

Coarse gravel <22.6 7 5.11 10.22

Coarse gravel <32.0 13 9.49 19.71

Very coarse gravel <45.3 17 12.41 32.12

Very coarse gravel <64.0 15 10.95 43.07

Small cobble <90.5 14 10.22 53.28

Small cobble <128 26 18.98 72.26

Large cobble <181 20 14.60 86.86

Large cobble <256 13 9.49 96.35

Boulder ≥256 5 3.65 100.00

Total 137 100.00

[Site: 17. 

Date: 08-16-2005. 

Type of site: Embryo. 

Location description: Ives Island, upper main channel, water’s edge. 

Substrate description: Cobble, gravel, boulder, periphyton covered. 

Vegetation description: Absent. 

GPS: Lat/Long. UTM Zone 10N. WGS 84. 

Waypoint: 45.62313231 -121.9881475]

Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 0 .00 .00

Very fine gravel <4.0 0 .00 .00

Fine gravel <5.6 1 .78 .78

Fine gravel <8.0 1 .78 1.56

Medium gravel <11.3 4 3.13 4.69

Medium gravel <16.0 5 3.91 8.59

Coarse gravel <22.6 4 3.13 11.72

Coarse gravel <32.0 7 5.47 17.19

Very coarse gravel <45.3 12 9.38 26.56

Very coarse gravel <64.0 12 9.38 35.94

Small cobble <90.5 19 14.84 50.78

Small cobble <128 29 22.66 73.44

Large cobble <181 27 21.09 94.53

Large cobble <256 7 5.47 100.00

Boulder ≥256 0 .00 100.00

Total 128 100.00

[Site: 18. 

Date: 08-16-2005. 

Type of site: Embryo.

Location description: Upper Ives Island, main channel side.

Substrate description: Cobble, gravel, some boulders, dry periphyton near 

pool of standing water.

Vegetation description: Absent.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62350572 -121.9881395]

Appendix 2. Substrate data and frequency graph by site.

Percent frequency finer

Cumulative percent finer

Site 17 - Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

Percent frequency finer

Cumulative percent finer

Site 18 - Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

16  Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 0 .00 .00

Very fine gravel <4.0 0 .00 .00

Fine gravel <5.6 0 .00 .00

Fine gravel <8.0 1 .78 .78

Medium gravel <11.3 1 .78 1.56

Medium gravel <16.0 11 8.59 10.16

Coarse gravel <22.6 12 9.38 19.53

Coarse gravel <32.0 13 10.16 29.69

Very coarse gravel <45.3 11 8.59 38.28

Very coarse gravel <64.0 17 13.28 51.56

Small cobble <90.5 15 11.72 63.28

Small cobble <128 22 17.19 80.47

Large cobble <181 23 17.97 98.44

Large cobble <256 2 1.56 100.00

Boulder ≥256 0 .00 100.00

Total 128 100.00

[Site: 21.

Date: 08-16-2005.

Type of site: Embryo.

Location description: Ives Island middle, main channel side, 0.6–0.9 meters 

of water.

Substrate description: Cobble, gravel, some boulder, periphyton covered.

Vegetation description: Absent.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62228238 -121.9908966]

Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 0 .00 .00

Very fine gravel <4.0 0 .00 .00

Fine gravel <5.6 0 .00 .00

Fine gravel <8.0 0 .00 .00

Medium gravel <11.3 4 2.96 2.96

Medium gravel <16.0 11 8.15 11.11

Coarse gravel <22.6 9 6.67 17.78

Coarse gravel <32.0 11 8.15 25.93

Very coarse gravel <45.3 18 13.33 39.26

Very coarse gravel <64.0 14 10.37 49.63

Small cobble <90.5 20 14.81 64.44

Small cobble <128 25 18.52 82.96

Large cobble <181 23 17.04 100.00

Large cobble <256 0 .00 100.00

Boulder ≥256 0 .00 100.00

Total 135 100.00

[Site: 22.

Date: 08-12-2005.

Type of site: Free embryo.

Location description: Upper Ives Island, main channel side, dry land site in 

August.

Substrate description: Cobble, gravel, dry periphyton covered.

Vegetation description: Sparse, edge of willows.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62495504 -121.9863766]

Appendix 2. Substrate data and frequency graph by site.—Continued

Percent frequency finer

Cumulative percent finer

Site 21 - Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

Percent frequency finer

Cumulative percent finer

Site 22 - Free Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

Appendixes 17
Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 0 .00 .00

Very fine gravel <4.0 0 .00 .00

Fine gravel <5.6 0 .00 .00

Fine gravel <8.0 1 .78 .78

Medium gravel <11.3 4 3.13 3.91

Medium gravel <16.0 10 7.81 11.72

Coarse gravel <22.6 8 6.25 17.97

Coarse gravel <32.0 19 14.84 32.81

Very coarse gravel <45.3 12 9.38 42.19

Very coarse gravel <64.0 25 19.53 61.72

Small cobble <90.5 19 14.84 76.56

Small cobble <128 21 16.41 92.97

Large cobble <181 8 6.25 99.22

Large cobble <256 1 .78 100.00

Boulder ≥256 0 .00 100.00

Total 128 100.00

[Site: 31.

Date: 08-12-2005.

Type of site: Free embryo.

Location description: Upper Ives Island, main channel side, dry land site in 

August.

Substrate description: Cobble, gravel, dry periphyton covered.

Vegetation description: Moderate coverage, willows.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62489829 -121.9864324]

Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 4 3.13 3.13

Very fine gravel <2.8 1 .78 3.91

Very fine gravel <4.0 0 .00 3.91

Fine gravel <5.6 0 .00 3.91

Fine gravel <8.0 2 1.56 5.47

Medium gravel <11.3 6 4.69 10.16

Medium gravel <16.0 9 7.03 17.19

Coarse gravel <22.6 9 7.03 24.22

Coarse gravel <32.0 11 8.59 32.81

Very coarse gravel <45.3 13 10.16 42.97

Very coarse gravel <64.0 21 16.41 59.38

Small cobble <90.5 20 15.63 75.00

Small cobble <128 20 15.63 90.63

Large cobble <181 10 7.81 98.44

Large cobble <256 2 1.56 100.00

Boulder ≥256 0 .00 100.00

Total 128 100.00

[Site: 32.

Date: 08-12-2005.

Type of site: Free embryo.

Location description: Upper Ives Island, main channel side, dry land site in 

August.

Substrate description: Cobble, gravel, dry periphyton covered.

Vegetation description: Heavy coverage, willows.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62493341 -121.9865616]

Appendix 2. Substrate data and frequency graph by site.—Continued

Percent frequency finer

Cumulative percent finer

Site 31 - Free Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

Percent frequency finer

Cumulative percent finer

Site 32 - Free Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

18  Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 1 .77 .77

Very fine gravel <4.0 0 .00 .77

Fine gravel <5.6 1 .77 1.54

Fine gravel <8.0 6 4.62 6.15

Medium gravel <11.3 3 2.31 8.46

Medium gravel <16.0 8 6.15 14.62

Coarse gravel <22.6 11 8.46 23.08

Coarse gravel <32.0 12 9.23 32.31

Very coarse gravel <45.3 16 12.31 44.62

Very coarse gravel <64.0 20 15.38 60.00

Small cobble <90.5 14 10.77 70.77

Small cobble <128 28 21.54 92.31

Large cobble <181 10 7.69 100.00

Large cobble <256 0 .00 100.00

Boulder ≥256 0 .00 100.00

Total 130 100.00

[Site: 33.

Date: 08-12-2005.

Type of site: Embryo.

Location description: Upper Ives Island, shallow water at eastern tip island, 

start of side channel.

Substrate description: Cobble, gravel, periphyton covered.

Vegetation description: Absent.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62611006 -121.9854349]

Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 0 .00 .00

Very fine gravel <4.0 1 .77 .77

Fine gravel <5.6 5 3.85 4.62

Fine gravel <8.0 7 5.38 10.00

Medium gravel <11.3 5 3.85 13.85

Medium gravel <16.0 10 7.69 21.54

Coarse gravel <22.6 7 5.38 26.92

Coarse gravel <32.0 18 13.85 40.77

Very coarse gravel <45.3 19 14.62 55.38

Very coarse gravel <64.0 24 18.46 73.85

Small cobble <90.5 21 16.15 90.00

Small cobble <128 9 6.92 96.92

Large cobble <181 4 3.08 100.00

Large cobble <256 0 .00 100.00

Boulder ≥256 0 .00 100.00

Total 130 100.00

[Site: 34.

Date: 08-16-2005.

Type of site: Embryo.

Location description: Upper Ives Island, shallow water at eastern tip island, 

start of side channel.

Substrate description: Cobble, gravel, periphyton covered.

Vegetation description: Absent.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62628692 -121.9849599]

Appendix 2. Substrate data and frequency graph by site.—Continued

Percent frequency finer

Cumulative percent finer

Site 33 - Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

Percent frequency finer

Cumulative percent finer

Site 34 - Embryo Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

Appendixes 19
Class name Size class 

(millimeter)

No. of 

particles

Percent 

frequency

Cumulative 

percent 

finer

Fines <2.0 0 0.00 0.00

Very fine gravel <2.8 0 .00 .00

Very fine gravel <4.0 0 .00 .00

Fine gravel <5.6 2 1.56 1.56

Fine gravel <8.0 1 .78 2.34

Medium gravel <11.3 2 1.56 3.91

Medium gravel <16.0 7 5.47 9.38

Coarse gravel <22.6 6 4.69 14.06

Coarse gravel <32.0 11 8.59 22.66

Very coarse gravel <45.3 12 9.38 32.03

Very coarse gravel <64.0 23 17.97 50.00

Small cobble <90.5 26 20.31 70.31

Small cobble <128 26 20.31 90.63

Large cobble <181 12 9.38 100.00

Large cobble <256 0 .00 100.00

Boulder ≥256 0 .00 100.00

Total 128 100.00

[Site: 47.

Date: 08-16-2005.

Type of site: Larva.

Location description: Ives Island, middle, main channel side.

Substrate description: Cobble, gravel, dry periphyton covered.

Vegetation description: Sparse.

GPS: Lat/Long, UTM Zone 10N, WGS 84.

Waypoint: 45.62309953 -121.9894973]

Appendix 2. Substrate data and frequency graph by site.—Continued

Percent frequency finer

Cumulative percent finer

Site 47 - Larva Capture Site

PERCENT FREQUENCY FINER

0

5

10

15

20

25

PARTICLE SIZE CLASS FINER THAN, MM

2 2.8 4 5.6 8 11.3 16 22.6 32 45.3 64 90.5 128 181 256 GREATER

THAN 256

CUMULATIVE PERCENT FINER 0

20

40

60

80

100

20 Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon
Prepared by the USGS Publishing Network, 

Publishing Service Center, Tacoma, Washington

Bill Gibbs 

Bob Crist

Debra Grillo

Bobbie Jo Richey

For more information concerning the research in this report, contact the 

Director, Western Fisheries Research Center

Columbia River Research Laboratory, 

U.S. Geological Survey, 5501-A Cook-Underwood Road

Cook, Washington 98605

http://wfrc.usgs.gov/labs/columbia.htm
SIR 2006–5225 van der Leeuw and others Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon