U. S. Department of the Interior

Bureau of Land Management

BLM Alaska Open File Report 122

BLM/AK/GI-09/008+6600+AKF031

September 2009

Abundance and Run Timing of Adult Salmon in the 

Tozitna River, Alaska, 2007

Jason Post, Carl Kretsinger, and Bob Karlen

BLM

Alaska
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The Bureau of Land Management sustains the health, diversity and productivity of the public lands for the 

use and enjoyment of present and future generations.

Cover Photo

Aerial view of the weir and fish trap on the Tozitna River. BLM photograph by Jason Post.

Author

Jason Post, Carl Kretsinger, and Bob Karlen are fisheries biologists at the BLM Fairbanks District Office in 

Fairbanks, Alaska.

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Abundance and Run Timing of Adult Salmon 

in the Tozitna River, Alaska, 2007

Jason Post, Carl Kretsinger, and Bob Karlen

BLM-Alaska Open File Report 122

September 2009

U. S. Department of the Interior

Bureau of Land Management

i

The authors are grateful to the following individuals for 

providing data collection and assistance under sometimes 

challenging field conditions: Danielle Vent, Heather Craig, and 

Jessica Johnson, Student Temporary Employment Program, 

BLM; Tom Fogg, Darcy King, and Jill Klein, Yukon River 

Drainage Fisheries Association; Cindy Hamfler, Cal Westcott, 

Bill Bouley, Carl Kretsinger, and Seth Beaudreault, Bureau 

of Land Management, Fairbanks. We also want to thank the 

Alaska Department of Fish and Game, Commercial Fisheries 

Division, Anchorage for conducting the scale analysis. A special 

thanks goes to Jack Blume for the use of his private airstrip on 

the Tozitna River. The U.S. Fish and Wildlife Service, Office 

of Subsistence Management, Anchorage, provided $112,000 in 

funding through the Fisheries Resource Monitoring Program 

under FWS agreement number 70181-4-N193. Additional 

funding was provided by the Bureau of Land Management, 

Fairbanks District Office, Fairbanks.

ACKNOWLEDGMENTS

The Tozitna River project is a multi-agency study to 

determine escapement, run timing, and age-sex-length composition of adult Chinook and summer chum salmon in a middle 

Yukon River Basin tributary. A resistance board weir was operated from 23 June 2007 to 6 August 2007. For Chinook salmon 

the escapement was 494 and the age composition was 29.3% 

age 4, 34.6% age 5, 35.8% age 6, and .4% age 7. The Chinook 

sex composition from strata-weighted sample data was 25.8% 

female. For summer chum salmon the escapement was 14,147 

and the age composition was 1.6% age 3, 63.7% age 4, 32% age 

5, and 2.6% age 6. The summer chum sex composition from 

strata-weighted sample data was 43.3% female.

ABSTRACT

CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Weir and Trap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Escapement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Chinook Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Summer Chum Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Statistical Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Age-Sex-Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Spawning Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Abiotic Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Weir and Trap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Escapement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Chinook Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Summer Chum Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Age-Sex-Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Spawning Ground Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Downstream of Weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

Upstream of Weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Abiotic Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Chinook Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Summer Chum Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 

Fall Chum and Coho Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Future Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

TABLES

Table 1. Daily and cumulative counts for Chinook and summer chum salmon . . . . . . . . . . . . 9

Table 2. Female Chinook salmon composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 3. Age composition of Chinook salmon escapement by stratum and sex . . . . . . . . . . 11

Table 4. Chinook salmon mid-eye to fork length by age and sex . . . . . . . . . . . . . . . . . . . . . . 12

Table 5. Female summer chum salmon composition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Table 6. Age composition of summer chum salmon escapement by stratum and sex . . . . . 13

Table 7. Summer chum salmon mid-eye to fork length by age and sex . . . . . . . . . . . . . . . . 14

Table 8. Days, hours, and percentages of the monitoring period exceeding water 

temperature thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Table 9. Comparison of preliminary Chinook salmonage composition by sex at the East

Fork Andreafsky River, Gisasa River, Henshaw Creek, and the Tozitna River . . . 15

FIGURES

Figure 1. Location of the Tozitna River weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 2. Chinook salmon daily counts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 3. Summer chum salmon daily counts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

iii
iv

Figure 4. Chinook redds downstream of the weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 5. Summer chum redds downstream of the weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 6. Distribution of downstream Chinook redds by river segment . . . . . . . . . . . . . . . . . 20

Figure 7. Distribution of downstream summer chum redds by river segment . . . . . . . . . . . . 20

Figure 8. Chinook redds upstream of the weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 9. Summer chum redds upstream of the weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 10. Distribution of upstream Chinook redds by river segment . . . . . . . . . . . . . . . . . . . 23

Figure 11. Distribution of upstream summer chum redds by river segment . . . . . . . . . . . . . . 23

Figure 12. Location of the 4 weir projects monitoring Chinook salmon escapement in 

the Alaska portion of the Yukon River Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
BLM Open File Report 122 • September 2009 1

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

INTRODUCTION

Conservation of salmon in the Yukon River 

drainage is complex and challenging for 

fisheries managers because of several 

biological and social factors: mixed-stocks, 

large geographic spawning distribution, overlapping and compressed run timing, recent 

declines in escapement, multiple user groups, 

and multi-agency management. Several plans 

and policies have been created to manage 

the Yukon River salmon escapement (see 

Holder and Senecal-Albrecht 1998). Management of Yukon River salmon escapement is 

mostly based on sustained yield, defined as 

the average annual yield resulting from an 

escapement level that can be maintained on 

a continuing basis.

In 1998 the Yukon River Comprehensive 

Salmon Plan for Alaska (YRCSPA) was 

developed to improve salmon management in 

the Yukon Area. On 1 October 1999, the 

Federal Government joined the State of 

Alaska in managing Yukon River fisheries, 

assuming responsibility for subsistence 

fisheries management in inland navigable 

waters on, and adjacent to, federal conservation lands (Buklis 2002). 

The Bureau of Land Management (BLM) 

received a Congressional appropriation for 

Yukon River salmon restoration in 2000. 

In response to this appropriation, the BLM 

convened interagency coordination meetings 

to determine the most beneficial use of the 

funding. Emphasis was placed on funding 

projects that would satisfy both the BLM and 

Yukon River fisheries management. Yukon 

River fisheries managers placed a priority on 

addressing escapement and run-timing data 

gaps in the middle Yukon River Sub-Basin 

for Chinook Oncorhynchus tshawytscha and 

summer chum O. keta salmon, as identified 

in the YRCSPA (Holder and Senecal-Albrecht 

1998). After interagency coordination meetings, the BLM chose the Tozitna River as the 

site for an escapement study. The BLM had 

in 1986 designated the Tozitna River an Area 

of Critical Environmental Concern for the 

protection of salmon spawning habitat and 

had identified acquisition of baseline resource 

data as a management objective (BLM 1986; 

Knapman 1989). In addition to addressing 

data gaps identified in the YRCSPA, salmon 

escapement and run timing data collected on 

the Tozitna River would assist the BLM in 

fulfilling its management objectives.

Accurate escapement estimates from 

spawning tributaries are an important fisheries management tool used to assist in the 

determination of production, marine survival, 

harvest, and spawner recruit relationships 

(Neilson and Geen 1981; Labelle 1994). 

Although aerial escapement surveys on 

the Tozitna River have been conducted by 

the Alaska Department of Fish and Game 

(ADF&G) since 1959, results of aerial surveys 

are inherently variable (Schultz et al. 1993) 

and should only be used to examine trends 

in relative escapement abundance (Barton 

1984). Samples taken at weirs are considered 

to be the least biased and most accurate data 

available for assessing escapement and age 

composition of a mixed stock fishery (Halupka 

et al. 2000). 

To accurately assess escapement of 

Chinook and summer chum salmon in the 

Middle Yukon River Sub-Basin, the BLM 

has operated a resistance board weir on the 

Tozitna River since 2002. 

The objectives of the project are: 

1) Determine escapement of Chinook and 

summer chum salmon 

2) Describe the run timing of Chinook and 

summer chum salmon 

3) Estimate relative abundance of Chinook 

and summer chum salmon downstream of 

the weir and document spawning locations 

using aerial survey techniques 

4) Estimate the weekly age and sex proportions of Chinook salmon so that the 

simultaneous estimates have a 95% probability of being within .05 of the population 

proportion, and so that estimates for chum 

salmon have an a = .10 and d = .10 

Additional project tasks are: 

1) Measure water temperature, turbidity, 

precipitation, and stream stage; determine 

daily stream discharge

2) Provide ADF&G with scale samples from 

Chinook salmon to assist in the agency’s 

scale pattern analysis program
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BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

In addition, the BLM seeks to provide ADF&G 

with 7 to 10 years of accurate estimates of 

total abundance for adult Chinook and summer chum salmon in the Tozitna River so 

that escapement goals for this system can be 

addressed.

STUDY AREA

The Tozitna River is a large, clear-water, 

northern tributary to the middle Yukon River, 

with a watershed area of 4215 km2, 90% of 

which the BLM manages (Figure 1). The 

watershed originates in the southeastern Ray 

Mountains at 1676 m and flows southwesterly approximately 207 km to its confluence 

with the Yukon River (1096 river km), 16 km 

downstream of Tanana. The average yearly 

precipitation is 32 cm1 with 62% occurring 

between June and September. Average 

monthly ambient temperature ranges from 

–28 to 22 °C1. The river is usually ice-free in 

May, and freeze-up commonly occurs by 

November (J. Blume, Tozitna River homesteader, Fairbanks, personal communication). 

Peak discharge is correlated with spring 

snowmelt or high-intensity rainstorms during 

the summer. Water turbidity remains low 

for the period from late June through early 

August, except for periods of high-intensity 

precipitation. Fish species in the Tozitna

River include Chinook salmon, summer and 

fall chum salmon (Barton, 1984), coho 

salmon O. kisutch, sockeye salmon O. nerka, 

Dolly Varden Salvelinus malma, Arctic 

grayling Thymallus arcticus, northern pike 

Esox lucius, burbot Lota lota, round whitefish 

Prosopium cylindraceum, slimy sculpin Cottus 

cognatus, and longnose sucker Catostomus 

catostomus.

The weir site is located at lat 65°31.0980′ N, 

long 152°12.8622′ W, approximately 80 km 

upstream from the mouth of the Tozitna River 

and approximately 0.5 km upstream from the 

Tozitna River’s confluence with Dagislakhna 

Creek. The weir is located between a downstream riffle and upstream deep meander 

pool. At this location the average wetted width 

at summer flows is 52 m with an average 

depth of 0.6 m. This site is downstream of 

most Chinook salmon spawning (Kretsinger 

and Sundlov, in preparation). The crosssection is gradually sloping, and the substrate 

consists of sand to cobble.

METHODS

Weir and Trap

Salmon escapement, run timing, and 

composition were assessed by counting and 

sampling fish as they passed through the 

resistance board weir fitted with a live trap. 

Construction and installation of the weir were 

as described by Tobin (1994). The trap (fabricated by Mackey Lake Co., Soldotna, AK) was 

incorporated into the weir on the upstream 

side. The weir was 60 m wide and was operational on 23 June. The weir was cleaned and 

inspected on a daily basis to remove debris 

and ensure that the trap provided the only 

avenue for fish passage.

The Tozitna River weir has remained in 

the same location for the past 3 years (2005–

2007). In 2005 the weir was relocated 200 m 

downstream of its original (2002–2004) location due to a change in channel morphology. 

Escapement

All salmon passing through the weir and 

live trap were counted and identified to 

species. 

Observers wore polarized sunglasses to 

facilitate in fish identification. Counting 

occurred 24 hours per day, 7 days per week 

and consisted of four 6-hour shifts. During 

daily sampling efforts the trap could be closed 

for up to 45 minutes. On average, salmon 

were able to pass through the trap within 15 

minutes after entering. Hourly counts were 

summed to achieve a daily count (0000–2359 

hours). Run timing was calculated by the 

proportion of daily to cumulative passage 

to determine quartile (25%, 50%, and 75%) 

dates, peak, and median date of passage. 

Data Analysis

Chinook Salmon

Temporally stratified random sampling 

design (Cochran 1977) was used to collect 

11949–2003 average monthly temperature and 

precipitation data for the Tanana FAA Airport, Alaska, 

supplied by Western Regional Climate Center, Reno, 

Nevada. 
BLM Open File Report 122 • September 2009 3

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

and analyze age-sex-length (ASL) data, with 

statistical weeks defining strata. Strata 

began on Tuesday and ended the following 

Tuesday with a weekly sample size target of 

112 Chinook salmon distributed uniformly 

throughout the week (16 fish per day). The 

weekly sample goal allowed up to 5% of the 

scales to be illegible. An overall sample goal 

of 448 fish was established to achieve a probability of .95 that all of the estimates were 

simultaneously within .05 of the population 

proportions (Thompson 1987). All target 

species within the trap at the time of sampling were sampled to avoid bias. The first 

and last sampling strata were greater than 

a week because of low escapement for those 

periods.

Summer Chum Salmon

Sampling for chum salmon was done in 

much the same manner as the sampling for 

Chinook. The only difference was that the 

weekly sample goal for chum was established 

using the method described by Bromaghin 

(1993) so that simultaneous interval estimates 

of sex and age proportions for each week had 

.90 probability of being within .10 of population proportions. Strata began on Thursday 

and ended the following Wednesday with a 

weekly sample size target of 175 chum salmon 

distributed uniformly throughout the week 

(25 fish per day). The first sampling stratum 

was greater than a week because of low escapement for that period, and the last sampling stratum was shortened due to flooding. 

The weekly sample goal allowed up to 15% of 

the scales to be illegible. 

Statistical Method

Within a given stratum m, the proportion of 

species i passing the weir that are of sex j and 

age k (Pijkm) is estimated as

Pijkm = nijkm / ni++m

where nijkm denotes the number of fish of 

species i, sex j, and age k sampled during 

stratum m and a subscript of “+” represents 

summation over all possible values of the 

corresponding variable, e.g., ni++m denotes the 

total number of fish of species i sampled in 

stratum m. The variance of Pijkm is estimated as

v(Pijkm)=(1–ni++m /Ni++m)(Pijkm(1 – Pijkm)/ ni++m –1), 

where Ni++m denotes the total number of 

species i fish passing the weir in stratum m. 

The estimated number of fish of species i, sex 

j, age k passing the weir in stratum m (Nijkm) is

Nijkm = Ni++m Pijkm,

with estimated variance

v(Nijkm) = N2

i++mv(Pijkm)

Estimates of proportions for the entire period 

of weir operation are computed as weighted 

sums of the stratum estimates, i.e., 

Pijk = Σ (Ni++m /Ni+++)Pijkm

 

m

and

v(Pijk) = Σ (Ni++m /Ni+++)2 v(Pijkm) m

The total number of fish in a species, sex, 

and age category passing the weir during the 

entire period of operation is estimated as

Nijk = Σ Nijkm,

 m

with estimated variance 

v(Nijk) = Σv(Nijkm)

 m

Age-Sex-Length

The live trap was used to capture salmon 

sampled for age, sex, and length. The upstream 

gate of the trap was closed for periods to obtain 

an adequate sample size. During sampling, a 

dip-net was used to capture salmon in the live 

trap. Salmon were then placed in a partially 

submerged, aluminum cradle for identifying 

species and sex, measuring, and removing 

scale(s). Lengths were measured to the nearest 

5 mm from mid-eye to fork of the caudal fin. 

Morphological maturation characteristics were 

used to determine sex. One scale for chum and 

3 scales for Chinook salmon were removed from 

the left side, 2 rows above the lateral line and 

on a diagonal line from the posterior end of the 

dorsal fin to the anterior end of the anal fin 

(Anas 1963; Mosher 1968). Scales were then 

placed on numbered gum cards and sent to the 
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BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

ADF&G Division of Commercial Fisheries in 

Anchorage for aging. Aging was conducted by 

creating impressions on cellulose acetate cards 

with a heated hydraulic press (Clutter and 

Whitsel 1956) and then examining the scale 

annuli patterns (Gilbert 1922). European 

notation (Koo 1962) was used to record the 

ages. A holding pen (6 m × 2 m) was constructed adjacent to the trap, and after sampling, 

fish were transferred and held for 0.5 hours. 

The holding pen allowed sampled fish to 

recover in an area out of the main current. 

Spawning Locations

Aerial surveys were conducted by helicopter on the entire length of the Tozitna River 

to document the abundance and location of 

Chinook and summer chum spawning areas 

(redds). Observers wore polarized sunglasses 

to facilitate locating and counting redds, 

which were then recorded with GPS equipment. Some reaches of the river contained 

high concentrations of redds; in these areas, 

observers estimated the number of redds. 

The survey was broken into 2 segments. The 

first segment started at the mouth of the 

Tozitna River and ended at the fish weir, and 

the second segment started at the fish weir 

and ended a few kilometers beyond the upper 

reaches of spawning. 

Abiotic Measurements

Water temperature, turbidity, precipitation, and stream stage (water surface 

elevation) measurements were collected daily 

from 22 June to 11 August. Water temperature was monitored with an Onset TidbiT®

temperature logger placed on the stream 

bottom in a shaded location within a deep 

(>1 m) meander pool upstream from the weir. 

Water temperature was recorded every hour. 

Turbidity was measured using a Hach 2100P 

Portable Turbidimeter. Precipitation for the 

previous 24 hours was measured daily with a 

rain gauge. A staff gauge was used to record 

daily variation in stream stage.

To determine stream discharge, water 

velocity was measured over a range of stream 

stage elevations using a Price AA current 

meter. Stream stage was used as the independent variable to estimate stream discharge 

for days when discharge was not measured. 

Annual stream stage versus discharge 

ratings can be developed by combining the 

direct discharge measurements and computersimulated peak flow using log-log regression 

(Rantz et al. 1982). 

RESULTS

Weir and Trap

Weather systems in the summer often 

bring periods of rain to the interior of Alaska 

and result in elevated stream discharge in 

the Tozitna River. During these periods of 

increased discharge, weir panels can become 

submerged, allowing salmon to migrate over 

the weir undetected. In 2007 heavy rain in 

the upper Tozitna River watershed during the 

first week of August forced closure of the fish 

trap at 0500 on 6 August after the weir panels 

became submerged. This high-water event 

marked the end of escapement counts and 

sampling for the 2007 season. The weir and 

trap were completely removed on 12 August. 

Escapement

Chinook Salmon

Chinook salmon (N = 494) passed through 

the weir from 3 July to 5 August (Table 1). 

Daily Chinook escapement during the last 3 

days of counting was <1% of the cumulative 

escapement. The quartile dates (25%, 50%, 

and 75%) of cumulative passage for Chinook 

salmon were 13 July, 20 July, and 24 July, 

respectively (Table 1; Figure 2). The date of 

peak passage was 23 July (n = 51), and the 

12-day period of 13 July to 24 July accounted 

for 50% of the escapement (Figure 2). 

Summer Chum Salmon

Summer chum salmon (N = 14,147) 

migrated through the weir from 3 July to 

6 August (Table 1). Daily chum escapement 

for the last three complete days of counting 

averaged 7.7% of the cumulative escapement. 

Escapement counts were incomplete due to 

missed counts from high water; quartiles 

dates are therefore approximate. The quartile 

dates (25%, 50%, and 75%) of cumulative 

passage for summer chum salmon were 25 

July, 29 July, and 2 August, respectively 

(Table 1; Figure 3). The date of peak passage 

was 23 July (n = 2890), and the 9-day period 
BLM Open File Report 122 • September 2009 5

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

of 25 July to 2 August accounted for 50% of 

the escapement (Figure 3). 

Age-Sex-Length

Chinook Salmon

The sex composition of Chinook salmon 

was 25.7% female, ranging from 2.9% 

(3 July to 10 July) to 38.2% (25 July to 

5 August) throughout weekly sampling 

strata (Table 2). Four age groups were 

identified from 217 readable scale samples. 

Overall, Chinook salmon were predominantly age 1.4 (35.4%) and age 1.3 (35%), 

followed by age 1.2 (29.2%) and age 1.5 

(.4%) (Table 3). Females were generally 

older (77.8% age 1.4 and 19.9% age 1.3) 

than males (42.6% age 1.3 and 40.4% age 

1.2). The structure of the run was influenced by sex and age, with the mean length 

of females age 1.3 and age 1.4 greater than 

that of same-age males. Females ranged 

from 700 mm to 910 mm, while the males 

ranged from 430 mm to 875 mm (Table 4). 

Summer Chum Salmon

The sex composition of summer chum 

salmon was 43.3% female, ranging from 

25.6% (12 July to 18 July) to 59.6% (2 August 

to 5 August) throughout weekly sampling 

stratum (Table 5). Four age groups were 

identified from 708 readable scale samples. 

Overall, chum salmon were predominantly 

age 0.3 (63.7%) and age 0.4 (32%), followed by 

age 0.5 (2.6%) and age 0.2 (1.6%) (Table 6). 

Females ranged from 420 to 630 mm, while 

males ranged from 500 to 695 mm (Table 7). 

Spawning Ground Survey

An aerial survey was conducted by 

helicopter to document spawning areas on 

the Tozitna River on 26 July. The survey 

began at the mouth of the Tozitna River 

and ended approximately 35 km upstream 

of the fish weir (Figures 4, 5, 8, 9). The first 

segment started at the mouth of the Tozitna 

River and ended at the weir (Figures 4, 5), 

and the second segment began at the weir 

and ended a few kilometers beyond the last 

observed Chinook redd (Figures 8, 9). Low 

water levels in the Tozitna River at the time 

of the survey provided very good observation 

conditions. 

Downstream of Weir

Observers recorded 22 Chinook redds and 

1084 summer chum redds downstream of the 

Tozitna River fish weir (Figures 4–7). These 

figures represented 16% of the total Chinook 

redds and 53% of the total summer chum 

redds observed in the Tozitna River, respectively. The majority of the Chinook redds 

(73%), as well as 53% of the summer chum 

redds, were found between Reindeer Creek 

and the weir. The survey revealed the importance of the river between Reindeer Creek and 

the weir for the spawning of both species.

Upstream of Weir

Observers recorded 116 Chinook redds 

and 968 summer chum redds upstream of the 

weir (Figures 8–11). These figures represented 84% of the total Chinook redds and 47% of 

the total summer chum redds in the Tozitna 

River, respectively. The Chinook redd observed farthest upstream was approximately 

32 km upstream of the weir and just below 

Fleshlanana Creek (Figure 8). Over half (55%) 

of these Chinook redds, as well as half (50%) of 

the summer chum redds, were observed within 

the 24 km stretch of river between Crooked 

Creek and McQuesten Creek. Similar results 

were found in 2005–2006 aerial surveys. 

Abiotic Measurements

Hourly water temperatures ranged from 

7 to 14.5 °C. The mean daily water temperature was 11.8 °C, slightly above the 7-year 

(2001–2007) average of 11.1 °C. During a 

majority (77%) of the monitoring period, water 

temperatures remained within those favorable 

for the migration (<15 °C) and the spawning 

and egg incubation (<13 °C) of salmon (Combs 

and Burrows 1957; Bell 1973; Hale 1981; 

McCullough 1999; Poole et al. 2001). However, 

water temperatures did at times exceed the 

State of Alaska standard for maximum water 

temperature during spawning and egg incubation (13 °C), as well as temperatures considered to cause elevated disease rates (14–17 °C) 

and reduced gamete viability (13–16 °C) in 

salmon (EPA 2001; Table 8). 

Turbidity (NTU) ranged from 0.7 to 56.6 

and averaged 4.28. Total precipitation for the 

period was 16.33 cm. Stream stage fluctuated 

from 155 to 34 cm and averaged 63 cm. 
 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

6

DISCUSSION

Chinook Salmon

The 2007 Yukon River Chinook run was 

expected to be average to below average and 

similar in abundance to the 2006 run, i.e., 

sufficient for escapements, a normal subsistence harvest, and a below-average commercial 

harvest (ADF&G 2007). All spawning escapement goals were met in Alaska, and in-season 

fishers’ reports suggested that most mainstem 

Yukon Area subsistence fishing households 

met their subsistence needs for salmon (JTC 

2008). The total commercial harvest of 33,634 

Chinook salmon was 23% below the 10-year 

(1997–2006) average for the Alaska portion of 

the Yukon River drainage (JTC 2008). 

The 2007 Chinook salmon escapement 

(494) on the Tozitna River was the lowest 

escapement count recorded since the project’s 

inception in 2001. The 2007 Chinook escapement was only 33% of the 5-year average 

(2002–2005, 2007) of 1480. Escapement 

counts from 2001 and 2006 were not included 

in the average because there was no commercial fishing on the Yukon River in 2001 and 

the Tozitna counts were incomplete in 2006. 

Two factors suggest that the 2007 Chinook 

escapement counts on the Tozitna River are 

accurate: (1) the first Chinook passed 9 days 

after the weir was installed, and (2) Chinook 

escapement during the last 3 days of counting 

was <1% of the cumulative escapement. With 

52% of the Chinook escapement sampled, the 

sex ratio of 25% female should likewise be 

considered accurate. This sex ratio is greater 

than the 5-year average of 21% female. Given 

an escapement of only 494 Chinook and a 

sex ratio of 25%, an estimated 127 females 

returned to spawn in 2007 (above the weir). 

Chinook run-timing and quartile dates 

were slightly later than normal in 2007. The 

first Chinook passed the Tozitna River weir 

on 3 July, just 3 days later than the 5-year 

average of 30 June. Quartile dates were also 

2 to 5 days later than the 5-year averages. The 

date of peak passage (51 Chinook) occurred on 

23 July, which was 8 days later than average. 

However, 50 Chinook (only 1 less than peak 

passage) passed through the weir on 13 July, 

which was only 2 days later than average. 

Two noticeable pulses of Chinook occurred in 

2007. The first pulse, which accounted for 

27% of the escapement, occurred 10 July to 

13 July. The second pulse, which accounted 

for 26% of the escapement, occurred 22 July to 

24 July. In contrast, the 8-day period between 

pulses only accounted for 24% of the escapement. A comparative analysis of run timing 

will be performed on 2001–2009 Tozitna 

River escapement data after the final season 

and will be included in the final report. Run 

timing will then be compared to subsistence 

and commercial fishing seasons in the Yukon 

River to determine if run timing is influenced 

by, and/or correlates with, open fishing seasons on the Yukon River. 

Summer Chum Salmon

The 2007 summer chum outlook was for 

an average to above average run. The run 

was expected to provide for escapement while 

supporting a normal subsistence harvest 

and a surplus of 500,000 to 900,000 fish for 

commercial harvest (ADF&G 2007). With a 

renewed market interest, numerous commercial seasons were directed at summer chum 

salmon in 2007 (ADF&G 2007). The total 

commercial harvest of 198,201 summer chum 

salmon was the tenth-lowest harvest for the 

Alaska portion of the Yukon River drainage 

since 1967 (ADF&G 2007) but 315% above the 

1997–2006 average harvest (JTC 2008). 

The 2007 summer chum salmon escapement count (14,147) for the Tozitna River was 

incomplete due to high water. The average 

daily escapement for the last 3 days of counting was 7% of the cumulative escapement. 

Given this average daily escapement count 

and run-timing dates from previous years, 

the 2007 total escapement was likely below 

the 4-year average (2001–2002, 2004, 2005) of 

24,067.

The date of the first chum passing through 

the weir, quartile dates, and the date of peak 

passage were 2 to 7 days later than the 4-year 

average. The sex ratio (43% female) was only 

slightly below the 6-year average (44%).

Fall Chum and Coho Salmon

BLM employees observed fall chum spawning in the lower reaches of the Tozitna River 

and coho salmon spawning in front of the 

Tozitna River fish camp on 2 October 2007. 
BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

7

However, very little is known regarding the 

abundance and spawning locations of these 

fall-run salmon populations. During a helicopter survey on 29 September 2008, BLM 

employees counted 50 fall chum and 200 coho 

in the Tozitna River. These counts may have 

been reduced by the late timing of the survey 

and by limited visibility in some areas due 

to shading, dark (algae) substrate, and slush 

ice. Further research would provide baseline 

fisheries information on these Middle Yukon 

River Drainage salmon populations and help 

the BLM assess current and potential subsistence resources in this region.

Future Plans

The Office of Subsistence Management 

approved funding the Tozitna River project 

through 2009. The BLM plans to use this 

funding to continue monitoring escapement, 

run timing, and age-sex-length composition 

of Chinook and summer chum on the Tozitna 

River. Additionally, the BLM would like to 

further monitor the ongoing low proportion of 

returning female Chinook to the Tozitna River 

as compared to the other 3 Yukon River Basin 

monitoring projects (Table 9; Figure 12). 

LITERATURE CITED

[ADF&G] Alaska Department of Fish and 

Game. 2007. 2007 preliminary Yukon 

River summer season summary. Alaska 

Department of Fish and Game, 

Division of Commercial Fisheries, 

Anchorage, Alaska. Available from: 

http://www.cf.adfg.state.ak.us/region3/

finfish/salmon/catchval/07yuksalsum.pdf 

Anas, R.E. 1963. Red salmon scale studies. In: 

International North Pacific Fisheries Commission annual report, 1961. Vancouver, 

British Columbia. p. 114–116.

Barton, L.H. 1984. A catalog of Yukon River 

salmon spawning escapement surveys. 

Alaska Department of Fish and Game, 

Technical Data Report 121, Juneau, 

Alaska.

Bell, M.C. 1973. Fisheries handbook of 

engineering requirements and biological 

criteria. Fisheries-Engineering Research 

Program, Corps of Engineers, North Pacific 

Division, Portland, Oregon. 

[BLM] Bureau of Land Management. 1986. 

Resource management plan and record of 

decision for the Central Yukon planning 

area. Bureau of Land Management, Kobuk 

District Office, Fairbanks, Alaska. 

Bromaghin, J.F. 1993. Sample size determination for interval estimation of multinomial 

probabilities. The American Statistician 

47(3):203–206.

Buklis, L.S. 2002. Subsistence fisheries 

management on federal public lands in 

Alaska. Fisheries 27(7):10–18.

Clutter, R.I., and L.E. Whitesel. 1956. Collection and interpretation of sockeye salmon 

scales. International Pacific Salmon Fisheries Commission Bulletin 9:1–159. 

Cochran, W.G. 1977. Sampling techniques, 

3rd ed. John Wiley and Sons, New York.

Combs, B.D. and R. E. Burrows. 1957. 

Threshold temperatures for the normal 

development of Chinook salmon eggs. 

Progressive Fish-Culturist 19(1):3–6. 

Gilbert, C.H. 1922. The salmon of the Yukon 

River. U.S. Bureau of Fisheries, Bulletin 

38:317–322.

Hale, S.S. 1981. Freshwater habitat relationships, chum salmon (Oncorhynchus keta). 

Alaska Department of Fish and Game, 

Habitat Division, Resource Assessment 

Branch, Anchorage, Alaska. 

Halupka, K.C., M.D. Bryant, M.F. Wilson, and 

F.H. Everest. 2000. Biological characteristics and population status of anadromous 

salmon in Southeast Alaska. U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station, 

General Technical Report: PNW-GTR-468, 

Juneau, Alaska.
8

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Holder, R.R., and D. Senecal-Albrecht (compilers). 1998. Yukon River comprehensive 

salmon plan for Alaska. Alaska Department 

of Fish and Game, Juneau, Alaska.

[JTC] Joint Technical Committee of the 

Yukon River US/Canada Panel. 2008. 

Yukon River salmon 2007 season summary 

and 2008 season outlook. Alaska Department 

of Fish and Game, Division of Commercial 

Fisheries, Regional Information Report 

3A08-01, Anchorage, Alaska.

Knapman, L.N. 1989. Watershed activity plan 

for the Tozitna River watershed Area of 

Critical Environmental Concern. Bureau of 

Land Management, Kobuk District Office, 

Fairbanks, Alaska.

Koo, T.S.Y. 1962. Age designation in salmon. 

In: Koo, T.S.Y, editor. Studies of Alaska red 

salmon. University of Washington Publications in Fisheries, New Series, Volume I, 

Seattle, Washington. p. 37–48.

Kretsinger, C.F., and T.J. Sundlov. In preparation. Abundance and run timing of adultsalmon, with observations of streamflow 

and water quality, in the Tozitna River 

Area of Critical Environmental Concern, 

Alaska. Bureau of Land Management, 

Fairbanks District Office, Fairbanks, 

Alaska.

Labelle, M. 1994. A likelihood method for 

estimating Pacific salmon based on fence 

counts and mark-recapture data. Canadian 

Journal of Fisheries and Aquatic Sciences 

51:552–566.

McCullough, D.A. 1999. A review and synthesis of effects of alterations to the water 

temperature regime on freshwater life 

stages of salmonids, with special reference 

to Chinook salmon. Report No. EPA 910-

RR-99-010, U.S. Environmental Protection 

Agency, Seattle, Washington.

Mosher, K. 1968. Photographic atlas of 

sockeye salmon scales. Fishery Bulletin 

67:243–280.

Neilson, J.D., and G.H. Geen. 1981. Enumeration of spawning salmon from spawner 

residence time and aerial counts. 

Transactions of the American Fisheries 

Society 110:554–556.

Poole, G., J. Dunham, M. Hicks, D. Keenan, J. 

Lockwood, E. Materna, D. McCullough, C. 

Mebane, J. Risley, S. Sauter, S. Spalding, 

and D. Sturdevant. 2001. Technical synthesis: scientific issues relating to temperature 

criteria for salmon, trout, and char native 

to the Pacific Northwest. Technical Report 

EPA 910-R-01-007, U.S. Environmental 

Protection Agency , Seattle, Washington. 

Rantz, S.E. 1982. Measurement and computation of streamflow. Volumes 1 and 2 of 

Water-Supply Paper 2175, U.S. Geological 

Survey, Washington, D.C.

Schultz, K.C., R.R. Holder, L.H. Barton, D.J. 

Bergstrom, C. Blaney, G.J. Sandone, and 

D.J. Schneiderhan. 1993. Annual management report for subsistence, personal use, 

and commercial fisheries of the Yukon 

area, 1992. Alaska Department of Fish and 

Game, Regional Information Report Number 3A93-10, Anchorage, Alaska. 

Tobin, J.H. 1994. Construction and performance of a portable resistance board weir 

for counting migrating adult salmon in 

rivers. U.S. Fish and Wildlife Service, 

Kenai Fishery Resource Office, Alaska 

Technical Report Number 22, Kenai, 

Alaska.

Thompson, S.K. 1987. Sample size for estimating multinomial proportions, The American 

Statistician 41:42–46. 
BLM Open File Report 122 • September 2009 9

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Table 1. Daily and cumulative counts for Chinook and summer chum salmon with the second 

quartile, median, and third quartile highlighted; Tozitna River, Alaska, 2007. 

Chinook Summer chum

Daily

Count

Cumulative Daily

 Count

Cumulative

Date Count Proportion Count Proportion

6/23 0 0 0.00 0 0 0.00

6/24 0 0 0.00 0 0 0.00

6/25 0 0 0.00 0 0 0.00

6/26 0 0 0.00 0 0 0.00

6/27 0 0 0.00 0 0 0.00

6/28 0 0 0.00 0 0 0.00

6/29 0 0 0.00 0 0 0.00

6/30 0 0 0.00 0 0 0.00

7/1a 0 0 0.00 0 0 0.00

7/2a 0 0 0.00 0 0 0.00

7/3 1 1 0.00 1 1 0.00

7/4 1 2 0.00 5 6 0.00

7/5 0 2 0.00 0 6 0.00

7/6 1 3 0.01 6 12 0.00

7/7 1 4 0.01 32 44 0.00

7/8 5 9 0.02 62 106 0.01

7/9 9 18 0.04 31 137 0.01

7/10 26 44 0.09 79 216 0.02

7/11 47 91 0.18 148 364 0.03

7/12 8 99 0.20 105 469 0.03

7/13 50 149 0.30 135 604 0.04

7/14 17 166 0.34 26 630 0.04

7/15 0 166 0.34 31 661 0.05

7/16 -1 165 0.33 3 664 0.05

7/17 11 176 0.36 13 677 0.05

7/18 17 193 0.39 97 774 0.05

7/19 29 222 0.45 115 889 0.06

7/20 23 245 0.50 332 1221 0.09

7/21 23 268 0.54 408 1629 0.12

7/22 48 316 0.64 708 2337 0.17

7/23 51 367 0.74 553 2890 0.20

-ContinuedaTrap closed (not fish-tight) due to high water and turbidity.
10

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Table 1 (cont.). Daily and cumulative counts for Chinook and summer chum salmon with the 

second quartile, median, and third quartile highlighted; Tozitna River, Alaska, 2007. 

Chinook Summer chum

Daily

Count

Cumulative Daily

 Count

Cumulative

Date Count Proportion Count Proportion

7/24 30 397 0.80 455 3345 0.24

7/25 16 413 0.84 718 4063 0.29

7/26 18 431 0.87 434 4497 0.32

7/27 8 439 0.89 1209 5706 0.40

7/28 6 445 0.90 874 6580 0.47

7/29 9 454 0.92 1264 7844 0.55

7/30 9 463 0.94 856 8700 0.61

7/31 8 471 0.95 777 9477 0.67

8/1 10 481 0.97 919 10396 0.73

8/2 13 494 1.00 767 11163 0.79

8/3 -1 493 1.00 1233 12396 0.88

8/4 0 493 1.00 627 13023 0.92

8/5 1 494 1.00 1119 14142 1.00

8/6a 0 494 1.00 5 14147 1.00

a Trap closed (not fish-tight) due to high water and turbidity.

Table 2. Female Chinook salmon composition for the Tozitna River, Alaska, 2007. 

SE = Standard Error.

Stratum 

Dates

 Sample Escapement

n # Females % Female

 Weir 

Count

Estimated 

# Females

% Female 

(of total 

escapement) SE

7/3–7/10 35 1 2.9 44 1 0.3 2.9

7/11–7/17 90 17 18.9 132 25 5 4.2

7/18–7/24 100 29 29 221 64 13 4.6

7/25–8/5 34 13 38.2 97 37 7.5 8.5

All Strata 259 60 – 494 127 25.8 2.9
BLM Open File Report 122 • September 2009 11

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007 Brood Year and Age 2004 2003 2002 2001 2000 1.1 1.2 1.3 1.4 1.5 Stratum Dates Weir Count Sex # Fish Sampled

%

%

%

%

%

% 

Escapement

7/3–7/10 44

M 32 0.0 4.8 5.2 1.8 0.0

8.9

F 1 0.0 0.0 1.0 0.0 0.0

Subtotal 33

7/11–7/17 132

M 54 0.0 12.2 10.5 7.2 0.0

26.7

F 12 0.0 0.0 3.0 13.6 1.5

Subtotal 66

7/18–7/24 221

M 61 0.0 13.2 21.5 7.6 0.0

44.7

F 27 0.0 0.0 3.8 47.6 0.0

Subtotal 88

 7/25–8/5 97

M 18 0.0 9.8 5.4 0.9 0.0

19.6

F 12 0.0 0.0 4.9 24.5 0.0

Subtotal 30 100

Combined Strata

362a M 165 0.0 (0) 39.9 (7.9) 42.5 (7.9) 17.5 (5.5)

0 (0) 100

132a F 52 0.0 (0)

0 (0) 12.7 (8.4) 85.7 (9.1) 1.5 (4.3) 100

Total 494 217

– – 

–

–

–

–

Age Composition With Sexes Combined 0.0 (0) 29.3 (6.3) 34.6 (6.4) 35.8 (6.4) .4 (0) 100

aEstimated number of male and female salmon derived from stratum-weighted ASL data.

Table 3. Age composition of Chinook salmon escapement by stratum and sex for the Tozitna River, Alaska, 2007. Standard error in parenthesis.
12

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Age Sex Sample Mean SE Range

1.1

Male 0

Female 0

1.2

Male 65 531 5.8 430–620

Female 0

1.3

Male 70 686 5.7 590–850

Female 7 756 15 700–800

1.4

Male 30 761 7.8 650–875

Female 44 820 6.8 730–910

1.5

Male 0

Female 1 900 900

Table 4. Chinook salmon mid-eye to fork length (mm) by age 

and sex for the Tozitna River, Alaska, 2007. SE = Standard 

Error.

Stratum 

Dates

 Sample Escapement

n # Females % Female

 Weir 

Count

Estimated 

# Females

% Female 

(of total 

escapement) SE

7/3–7/11 110 37 33.6 364 122 0.87 4.5

7/12–7/18 168 43 25.6 410 105 0.74 3.4

7/19–7/25 235 74 31.5 3289 1036 7.32 3.0

7/26–8/1 183 76 41.5 6333 2630 18.59 3.7

8/2–8/5 94 56 59.6 3751 2235 15.80 5.1

All Strata 790 286 – 14,147 6,128 43.3 2.2

Table 5. Female summer chum salmon composition for the Tozitna River, Alaska, 2007. SE = 

Standard Error.
BLM Open File Report 122 • September 2009 13

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Brood Year and Age

2004 2003 2002 2001

0.2 0.3 0.4 0.5

Stratum Dates

Weir 

Count Sex

# Fish 

Sampled

%

%

%

%

% 

Escapement

7/3–7/11 364

M 60 0.0 1.3 1.5 0.1

3.0

F 31 0.1 1.0 0.7 0.2

Subtotal 91

7/12–7/18 410

M 104 0.2 2.3 1.1 0.1

3.7

F 38 0.2 0.9 0.5 0.1

Subtotal 142

7/19–7/25 3,289

M 151 1.3 19.2 7.5 0.4

28.4

F 66 0.2 12.2 4.0 0.0

Subtotal 217

7/26–8/1 6,333

M 99 0.5 27.2 15.6 2.3

45.6

F 72 0.6 31.0 11.5 0.6

Subtotal 171

8/2–8/5 3,751

M 36 0.0 12.3 6.4 0.5 19.3

F 51 0.0 20.5 14.8 0.7

Subtotal 87

Combined Strata

362a M 450 2.0 (1.1) 62.3 (5.8) 32.3 (5.6) 3.4 (2.2) 100.0132a F 258 1.2 (1.6) 65.6 (6.1) 31.6 (5.9) 1.6 (1.7) 100.0

Total 494 708 - - - - -Age Composition With Sexes Combined 1.6 (0.9) 63.7 (4.1) 32 (4.0) 2.6 (1.4) 100

aEstimated number of male and female salmon derived from stratum-weighted ASL data.

Table 6. Age composition of summer chum salmon escapement by stratum and sex for the Tozitna River, Alaska, 2007. Standard error in parenthesis.
14

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Table 7. Summer chum salmon mid-eye to fork length (mm) by 

age and sex for the Tozitna River, Alaska, 2007. SE = Standard 

Error.

Age Sex Sample Mean SE Range

0.2

Male 13 560 1.1 520–605

Female 9 517 1.6 420–585

0.3

Male 275 567 5.8 500–670

Female 164 544 6.1 460–610

0.4

Male 149 583 5.6 520–695

Female 78 550 5.9 480–620

0.5

Male 13 582 2.2 530–610

Female 7 576 1.7 545–630

State Water 

Quality Standard for Max. 

Migration 

Temp. 

(>15 °C)

State Water 

Quality Standard for Max. 

Spawning and 

Egg Incubation Temp.

(>13 oC)

Reduced 

Gamete 

Viability

(13–16 °C)

Elevated 

Disease Rate

(14–17 oC)

50% PreHatch 

Mortality

(≥16 oC)

No. days 

exceeding the parameter during the 

monitoring period

0 29 29 10 0

Avg. hours /day 

exceeding the parameter

0 9.8 9.8 3.8 0

% of monitoring period exceeding the 

parameter (hourly 

basis)

0 23.2 23.2 3.1 0

Table 8. Number of days, average hours per day, and percentage of the monitoring period (22 

June to 11 August 2007) in which the water temperatures of the Tozitna River at the weir site 

exceeded water temperature threshold values considered to have an effect on salmon health 

and reproduction. The water quality standards and health and reproduction temperature 

threshold values are from 18 Alaska Administrative Code 70 and Poole et al. (2001). 
BLM Open File Report 122 • September 2009 15

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007 Brood year and Age 2004 2003 2002 2001 2001 2000 2000 Total 1.1 1.2 1.3 1.4 2.3 1.5 2.4 Location River (km)

a

Sample Size Sex

%

%

%

%

%

%

%

%

EF AndreafskyWeir 167 631b

Males

0 25.5 18 11.5

0 0.4

0 55.3

Females

0 16.2 7.7 20.6

0 0.3

0 44.7

Subtotal

0 41.7 25.7 32

0 0.6

0 100

Gisasa Weir 908 336b

Males

0 26.1 17.9 16.7 0.2

0

0 61

Females

0 4.2 2.8 31.7

0 0.2

0 39

Subtotal

0 30.4 20.7 48.5 0.2 0.2

0 100

HenshawWeir 1,539 258b

Males

0 46.6 15.9 12.6

0

0

0 75.1

Females

0

0 4.5 20.5

0

0

0 24.9

Subtotal

0 46.6 20.4 33

0

0

0 100

Tozitna Weir 1,096 217b

Males

0 30 32.2 13.8

0

0

0 76

Females

0

0 3.2 20.3

0 0.5

0 24

Subtotal

0 30 35.5 34.1

0 0.4

0 100

aKilometers from the Flat Island test fishing site near the south mouth of the Yukon River to the 

confluence of the listed tributary.

bAge data obtained from ADF&G, 2007.

Table 9. Comparison of preliminary Chinook age composition by sex at the East Fork Andreafsky River, Gisasa River, Henshaw Creek, and the Tozitna River, Alaska for 2007.
16

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 1. The 2007 location of the Tozitna River weir, Alaska.
BLM Open File Report 122 • September 2009 17

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 2. Chinook salmon daily counts with quartiles (25%, 50%, and 75%) of cumulative escapement for the period 23 June – 6 August, 2007, Tozitna River, Alaska.

Figure 3. Summer chum salmon daily counts with quartiles (25%, 50%, and 75%) of 

cumulative escapement for the period 23 June–6 August, 2007, Tozitna River, Alaska.

Date

Count Count

Date
18

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 4. Number and distribution of Chinook redds downstream of the Tozitna 

River fish weir in 2007.
BLM Open File Report 122 • September 2009 19

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 5. Number and distribution of summer chum redds downstream of the 

Tozitna River fish weir in 2007.
20

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 6. Distribution of Chinook redds downstream of the 

Tozitna River fish weir in 2007. 

Figure 7. Distribution of summer chum redds downstream of the 

Tozitna River fish weir by river segment in 2007. 
BLM Open File Report 122 • September 2009 21

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 8. Number and distribution of Chinook redds upstream of the Tozitna River fish weir in 2007.
22

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 9. Number and distribution of summer chum redds upstream of the Tozitna River fish weir in 2007.
BLM Open File Report 122 • September 2009 23

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 10. Distribution of Chinook redds upstream of the Tozitna 

River fish weir in 2007. 

Figure 11. Distribution of summer chum redds upstream of the 

Tozitna River fish weir in 2007. 
N

0 100 km

24

 

BLM Open File Report 122 • September 2009

Abundance and Run Timing of Adult Salmon in the Tozitna River, Alaska, 2007

Figure 12. Location of the 4 weir projects monitoring Chinook salmon escapement 

in the Alaska portion of the Yukon River Basin in 2007. The projects were located 

on the East Fork Andreafsky River, Henshaw Creek, Gisasa River, and the Tozitna 

River.