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Susitna‐Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
Eulachon run timing, distribution, and spawning in the Susitna River, Study
plan Section 9.16 : Initial study report -- Part A: Sections 1-6, 8-10
SuWa 223
Author(s) – Personal:
Author(s) – Corporate:
HDR, Inc.
LGL
AEA‐identified category, if specified:
Initial study report
AEA‐identified series, if specified:
Series (ARLIS‐assigned report number):
Susitna-Watana Hydroelectric Project document number 223
Existing numbers on document:
Published by:
[Anchorage : Alaska Energy Authority, 2014]
Date published:
June 2014
Published for:
Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Final or Draft status, as indicated:
Document type:
Pagination:
88 pages in various pagings
Related work(s):
Eulachon run timing, distribution, and spawning in the Susitna
River (Study 9.16), 2015 proposed eulachon spawning habitat
study modifications, technical memorandum. (SuWa 234)
Pages added/changed by ARLIS:
Notes:
Contents of Part A: Sections 1-6, 8-10 -- Appendix A. Eulachon spawning habitat tables --
Appendix B. Side scan sonar images -- Appendix C. Side scan sonar images compared to
photographs.
The following parts of Section 9.16 appear in separate files: Part A ; Part B ; Part C ; Part D.
All reports in the Susitna‐Watana Hydroelectric Project Document series include an ARLIS‐
produced cover page and an ARLIS‐assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna‐watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Eulachon Run Timing, Distribution, and
Spawning in the Susitna River
Study Plan Section 9.16
Initial Study Report
Part A: Sections 1-6, 8-10
Prepared for
Alaska Energy Authority
Prepared by
HDR, Inc. and LGL
June 2014
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page i June 2014
TABLE OF CONTENTS
1. Introduction ....................................................................................................................... 1
2. Study Objectives................................................................................................................ 1
3. Study Area ......................................................................................................................... 2
4. Methods and Variances in 2013 ....................................................................................... 2
4.1. Objective 1: Determine Eulachon Run Timing and Duration in the Susitna
River .................................................................................................................. 2
4.1.1. Indices of Passage for Migrating Eulachon .................................... 2
4.1.2. Active Fish Sampling ...................................................................... 5
4.1.3. Variances from Study Plan ............................................................. 6
4.2. Objective 2: Identification and Mapping of Potential Eulachon Spawning Sites
........................................................................................................................... 7
4.2.1. Identifying Potential Spawning Locations Using Radio Telemetry 8
4.2.2. Confirming Spawning Locations .................................................. 11
4.3. Objective 3: Eulachon Spawning Habitat Characteristics .............................. 12
4.3.1. Feasibility of Acoustics to Determine Substrate Composition ..... 13
4.3.2. Physical Characteristics of Spawning Habitats ............................. 13
4.3.3. Variances from Study Plan ........................................................... 14
4.4. Objective 4: Eulachon Population Characteristics ......................................... 14
4.4.1. Baseline Population Characteristics .............................................. 14
4.4.2. Baseline Genetic Samples ............................................................. 15
4.4.3. Marine Fish Observations ............................................................. 15
4.4.4. Variances from Study Plan ........................................................... 16
5. Results .............................................................................................................................. 16
5.1. Objective 1 – Eulachon Run Timing and Duration ........................................ 16
5.1.1. Fixed Sonar ................................................................................... 16
5.1.2. Active Fish Sampling .................................................................... 16
5.2. Identification and Mapping of Potential Eulachon Spawning Sites ............... 17
5.2.1. Radio Telemetry ............................................................................ 17
5.2.2. Confirming Spawning Locations .................................................. 19
5.3. Eulachon Spawning Habitat Characteristics ................................................... 19
5.3.1. Feasibility of Acoustics to Determine Substrate Composition ..... 19
5.3.2. Physical Characteristics of Spawning Habitat .............................. 19
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page ii June 2014
5.4. Eulachon Population Characteristics .............................................................. 20
5.4.1. Baseline Population Characteristics .............................................. 20
5.4.2. Marine Fish Observations ............................................................. 20
6. Discussion......................................................................................................................... 20
6.1. Eulachon Run Timing and Duration ............................................................... 20
6.2. Identification and Mapping of Potential Eulachon Spawning Sites ............... 21
6.2.1. Radio Telemetry............................................................................ 21
6.2.2. Mobile Sonar Surveys ................................................................... 22
6.3. Eulachon Spawning Habitat Characteristics ................................................... 22
6.4. Eulachon Population Characteristics .............................................................. 23
6.5. Relationship to Other Studies ......................................................................... 23
7. Completing the Study ..................................................................................................... 23
8. Literature Cited .............................................................................................................. 23
9. Tables ............................................................................................................................... 25
10. Figures .............................................................................................................................. 38
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page iii June 2014
LIST OF TABLES
Table 4.1-1. Methods used in 2013 for processing acoustic data collected at the fixed
sonar station (Project River Mile 17.5). ................................................................................. 25
Table 4.1-2. Total number of fish by species sampled at dipnetting sites from Project
River Mile 11.0–19.2 in 2013. ............................................................................................... 26
Table 4.2-1. Daily tagging locations, numbers, and body sizes of male and female
eulachon tagged with radio transmitters in 2013. .................................................................. 27
Table 4.2-2. Summary of aerial survey effort for telemetry component of Susitna River
eulachon, 2013. ...................................................................................................................... 28
Table 4.2-3. Spawning site acoustic surveys compared to potential sites identified from
radio telemetry in 2013. ......................................................................................................... 29
Table 4.3-1. Summary of spawning site habitat mapping effort in 2013. .................................... 30
Table 5.2–1. Number, group size, and location of potential clusters of eulachon
identified by radio telemetry in the Susitna River, 2013. ...................................................... 31
Table 5.2-2. Location, date, and number of fish sampled at spawning sites from May 29–
June 13, 2013. ........................................................................................................................ 32
Table 5.2-3. Summary of spawning condition of eulachon sampled at each spawning site
in 2013. .................................................................................................................................. 33
Table 5.2-4. Summary of length (mm) of eulachon sampled at each spawning site in
2013. ...................................................................................................................................... 34
Table 5.3-1. Summarized water quality parameters collected at 28 spawning sites in
2013. ...................................................................................................................................... 35
Table 5.4-1. Sex ratio for all fish caught during dipnetting at sites from Project River
Mile 11.0 to 19.2 from May 28–June 16, 2013. .................................................................... 35
Table 5.4-2. Eulachon sex ratio (M:F) by date from fish caught during dipnetting at sites
from Project River Mile 11.0-19.2 in 2013. ......................................................................... 36
Table 5.4-3. Mean lengths and weights for eulachon sampled during dipnetting at sites
from Project River Mile 11.0-19.2 in 2013. ......................................................................... 36
Table 5.4-4. Overall age composition for eulachon sampled at dipnetting sites from PRM
11 to 19.2 during 2013. .......................................................................................................... 37
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page iv June 2014
LIST OF FIGURES
Figure 3.1-1. Map of eulachon project study area in 2013 from Project River Mile 0–60........... 39
Figure 4.1-1. Acoustic equipment deployed at the fixed site on May 30, 2013 at Project
River Mile 17.5. ..................................................................................................................... 40
Figure 4.2-1. Processing time (seconds) by date for eulachon radio tagged in 2013. ................. 41
Figure 4.2-2. Map of radio telemetry area of study in 2013, showing location of fish
tagging site and fixed station telemetry receivers. ................................................................. 42
Figure 4.2-3. DIDSON imaging sonar and X2 rotator deployed over the side of the boat
in 2013. .................................................................................................................................. 43
Figure 5.1-2. River height measured on the Susitna River at Susitna Station from May
28–June 17, 2013. .................................................................................................................. 45
Figure 5.1-3. DIDSON images of eulachon passing upstream in 2013. Angle echogram
(left), 15° subset of background subtracted DIDSON image (center) and
corresponding view of detected targets (right). ..................................................................... 46
Figure 5.1-4. Zoomed view of DIDSON angle echogram and corresponding fish tracks in
2013. ...................................................................................................................................... 47
Figure 5.1-5. Splitbeam echogram of eulachon passing the fixed sonar site (Project River
Mile 17.5) in 2013. ................................................................................................................ 48
Figure 5.1-6. Time series of track and density-based DIDSON estimates of eulachon
passage at the fixed sonar site (Project River Mile 17.5) in 2013. ........................................ 49
Figure 5.1-7. Comparison of track and density based DIDSON estimates of eulachon
passage at the fixed sonar site (Project River Mile 17.5) in 2013. ........................................ 50
Figure 5.1-8. Comparison of density-based DIDSON and echo integration splitbeam
estimates of eulachon passage at the fixed sonar site (Project River Mile 17.5) in
2013. ...................................................................................................................................... 50
Figure 5.1-9. Eulachon CPUE (fish/min) in 2013 by day at one spawning site (PRM 17.5)
and two non-spawning sites compared to daily water temperature at the fixed sonar
site (PRM 17.5). PRM = Project River Mile. ........................................................................ 51
Figure 5.2 – 1a. Potential spawning sites of eulachon in the Susitna River in 2013, based
on radio telemetry detections, Map 1 of 2. ............................................................................ 52
Figure 5.2 – 1b. Potential spawning sites of eulachon in the Susitna River in 2013, based
on radio telemetry detections, Map 2 of 2. ............................................................................ 53
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page v June 2014
Figure 5.2-2. Length frequency by sex for eulachon sampled at 28 spawning sites from
Project River Mile 10.5 to 50.3 in 2013. ............................................................................... 54
Figure 5.3-1. Location of historic eulachon spawning sites (blue) and spawning sites
surveyed in 2013 (purple) by Project River Mile. ................................................................. 55
Figure 5.4-1. Length frequency by sex for eulachon sampled at the fixed site (Project
River Mile 17.5) from May 31–June 15, 2013. .................................................................... 56
Figure 5.4-2. Weight frequency by sex for eulachon sampled at the fixed site (Project
River Mile 17.5) from May 31–June 15, 2013. ..................................................................... 56
Figure 5.4-3. Length, age and sex of eulachon sampled at non-spawning sites, 2013. ................ 57
Figure 5.4-4. Ages of eulachon caught per day during sampling near the fixed site from
May 31-June 15, 2013. .......................................................................................................... 58
Figure 6.1-1. Eulachon run timing in 2013 from the fixed station as compared to counts
from 1982 and 1983 studies. .................................................................................................. 58
APPENDICES
Appendix A: Eulachon Spawning Habitat Tables
Appendix B: Side Scan Sonar Images
Appendix C: Side Scan Sonar Images Compared to Photographs
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page vi June 2014
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
ADF&G Alaska Department of Fish and Game
AEA Alaska Energy Authority
CIBW Cook Inlet Beluga Whales
cm centimeter(s)
CPUE catch per unit effort.
dB decibel
DIDSON Dual Frequency Identification Sonar
DO Dissolved Oxygen
ESA Endangered Species Act
FERC Federal Energy Regulatory Commission
ft feet
GIS Geographic information system
GPS global positioning system
ILP Integrated Licensing Process
ISR Initial Study Report
km kilometer
kts knots
m meter(s)
m:f male to female sex ratio
MHz Megahertz
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page vii June 2014
Abbreviation Definition
mm millimeter(s)
ms millisecond(s)
m/s meters per second
PAD Pre-Application Document
PCE primary constituent elements
PRM Project River Mile
Project Susitna-Watana Hydroelectric Project
RSP Revised Study Plan
SPD Study Plan Determination
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 1 June 2014
1. INTRODUCTION
On December 14, 2012, Alaska Energy Authority (AEA) filed its Revised Study Plan (RSP) with
the Federal Energy Regulatory Commission (FERC or Commission) for the Susitna-Watana
Hydroelectric Project (FERC No. 14241) which included 58 individual study plans (AEA 2012).
Section 9.16 of the RSP described the Eulachon Run Timing, Distribution, and Spawning in the
Susitna River Study. This section focuses on collecting baseline information regarding eulachon
(Thaleichtys pacificus), which are an important prey species for the endangered Cook Inlet
beluga whale (CIBW; Delphinapterus leucas). This study has been designed to support the
CIBW Study (Study 9.17). RSP Section 9.16 provided goals, objectives, and proposed methods
for data collection regarding eulachon in the Susitna River.
On February 1, 2013, FERC staff issued a study plan determination (February 1 SPD) for 44 of
the 58 studies, approving 31 studies as filed and 13 with modifications. RSP Section 9.16 was
one of the 31 studies approved with no modifications.
Following the first study season, FERC’s regulations for the Integrated Licensing Process (ILP)
require AEA to “prepare and file with the Commission an initial study report describing its
overall progress in implementing the study plan and schedule and the data collected, including an
explanation of any variance from the study plan and schedule” (18 CFR 5.15(c)(1)). This Initial
Study Report (ISR) on Eulachon Run Timing, Distribution, and Spawning in the Susitna River
has been prepared in accordance with FERC’s ILP regulations and details AEA’s status in
implementing the study, as set forth in the RSP as approved by FERC’s February 1 SPD
(collectively referred to herein as the “Study Plan”).
2. STUDY OBJECTIVES
The goal of the study is to collect baseline information regarding eulachon (Thaleichtys
pacificus) run timing, distribution, and habitat use in the Susitna River in two years of study.
Eulachon are an important prey species for the endangered CIBW; therefore, this study has been
designed to support the CIBW Study (Study 9.17). Together with existing information, data
collected as part of this study will provide necessary baseline information to address issues
identified in the Pre-Application Document (PAD) and assess potential Project effects (AEA
2011).
The objectives of this baseline study are as follows:
1) Determine eulachon run timing and duration in the Susitna River in 2013 and 2014.
2) Identify and map eulachon spawning sites in the Susitna River.
3) Characterize eulachon spawning habitats.
4) Describe population characteristics of eulachon returning in 2013 and 2014.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 2 June 2014
3. STUDY AREA
As established in RSP Section 9.16.3, the eulachon study extends from the mouth of the Susitna
River to the uppermost extent of spawning, which was determined by a combination of telemetry
and acoustics to be approximately PRM 60 (Figure 3.1-1). This is within the area sampled daily
in 1983 (ADF&G 1984), when few spawning locations were detected below PRM 10.
4. METHODS AND VARIANCES IN 2013
Eulachon field studies were conducted from ice out (May 28) through June 16 in 2013. Acoustic
sampling was used at a fixed site in the Lower River to assess the timing and duration of the
spawning migration, and assess relative abundance of eulachon. Active capture methods were
used to confirm eulachon spawning concentrations, collect information on eulachon population
characteristics, and document incidental observations of marine fish species. Telemetry and
mobile acoustic surveys were used jointly to identify the distribution of spawning locations in the
study area and to evaluate fish behavior on spawning sites. Physical habitat characteristics were
measured at confirmed spawning sites.
4.1. Objective 1: Determine Eulachon Run Timing and Duration in
the Susitna River
AEA implemented the methods as described in the Study Plan in 2013 with the exception of
variances explained below (Section 4.1.3).
Tasks to address Objective 1 included:
• Obtaining indices of passage over time for migrating eulachon using multibeam dual
frequency identification sonar (DIDSON) and splitbeam sonar.
• Confirming eulachon presence with active fish sampling.
• Processing multibeam sonar data to provide counts and relative abundance estimates of
fish moving upstream over time.
4.1.1. Indices of Passage for Migrating Eulachon
4.1.1.1. Fixed Station Operation
Two types of acoustic equipment were positioned on the right bank at PRM 17.5 to detect
migrating eulachon: a standard DIDSON imaging sonar and a BioSonics DTX system with a
circular 6° 210 kHz splitbeam transducer (Figure 4.1-1). The site was selected because it was (1)
upstream of tidal influence; (2) had a continuous slope of approximately 7 degrees, which
provided an unobstructed view over a range of 10 m (32.8 ft); and (3) was near high ground
where the acoustic surface units, laptop computer, 12-V battery bank supply, and generator could
be placed.
The two transducers were mounted side-by-side on an H-type aluminum frame that allowed
adjustments of the elevation and pitch angle for both transducers. The mount was placed in
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 3 June 2014
approximately 2.5 ft to 3 ft of water, with the center of the DIDSON lens 5 inches off the bottom,
and aimed approximately perpendicular to the river channel. Because both the splitbeam and
DIDSON were mounted on the same plate, pitch and elevation were identical for both sonars.
The mount was moved with the water level (onshore when the water level was rising) and reset
as necessary as the flood eroded and reshaped the sandbar.
A weir constructed of an aluminum frame with vexar plastic mesh was initially placed
downstream of the transducer mount. The purpose of the weir was to guide eulachon so they
would pass at least 0.7 m (2.3 ft) offshore from the transducer, where the acoustic beams have
spread sufficiently to provide adequate coverage and reduce the chance of eulachon shadowing
the entire sound field. However, the weir had to be removed for most of the sampling period
because flood conditions made it too difficult to keep the weir clean. It also appeared that ripples
created downstream of obstructions such as the weir tended to trigger the formation of spawning
aggregations.
Data were collected at the fixed sonar station from May 28 through June 14. From June 1
through June 4, equipment was removed from the water because of unstable river conditions.
The mobile DIDSON system (see Section 4.2.2.1) was used during this period to collect one or
two samples per day from a boat held stationary at the fixed site. Continuous sampling with the
stationary sonars was resumed on June 4 after the water level stabilized.
DIDSON data were recorded with DIDSON Viewer Version 5.25.43. After some
experimentation with window length, focus, frame rate, and frequency settings, data were
recorded with a systematic sampling scheme that cycled between 5 and 10 m (16.4 and 32.8 ft)
window lengths, at 10 and 8 frames per second, respectively, 3 minutes each, every 15 minutes,
providing a total sampling time of 24 minutes per hour. To assess the effect of frame rate and
absorption, samples recorded with a 10-m (32.8-ft) window length alternated between high (1.8
MHz, 96 beams) and low (0.8 MHz, 48 beams) frequency modes. For the 5-m (16.4-ft) window,
all data were recorded in high frequency mode (because over a short-range absorption frame rate
limitations are negligible).
Splitbeam data were acquired with Visual Acquisition Version 6.0. Data were recorded
continuously with a -70 dB threshold, 10 m (32.8 ft) maximum range, 20 pings per second, and a
0.2 ms pulse length.
4.1.1.2. Data Summary and Analysis
Raw DIDSON data were pre-processed in DIDSON Viewer 5.25.43, using its dynamic
background removal function to remove static image background (i.e., reflections from the river
bottom). Preprocessed files were loaded into Echoview for further image processing, target
detection, and tracking. The images were smoothed with a 3x3 median convolution. The goal of
the convolution was to join image pixels (“pixel” is used synonymously with acoustic data
sample) that belong to one object (e.g., fish) into one contiguous group of pixels that are brighter
than the surrounding background. To reduce problems with overlapping traces created by fish
detected at the same range, the images were truncated to a 15° field of view. Targets were
detected as contiguous samples with intensity >7 dB (low frequency images) or 9 dB (high
frequency images). The detection threshold was chosen such that it produced detections whose
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 4 June 2014
outlines provide, on average, a good match with a visual perception of the outline of the fish
image.
Next, the detected targets were filtered to eliminate as many false targets (e.g., noise created by
forward scatter) as possible while retaining as many true fish targets as possible. The filter
parameters differed depending on the final processing steps. Target tracking is more robust than
density-based estimates with regard to gaps in the series of images that are produced by an
individual fish over successive frames (as it moves through the 96 beams). Therefore, data files
that were further processed with tracking used a target threshold of 14 cm (5.5 inches) (only
targets estimated to be >14 cm (5.5 inches) are retained). For data files that were processed for
density-based estimates a more liberal threshold of 11 cm (4.3 inches) was used, which also
retains fish images that are artificially truncated (e.g., through shadowing or on the edges of the
beam). The validity of this approach was empirically tested with a subset of the data that was
processed both ways. Density and track-based estimates produced results that were in good
agreement with one another and with a visual inspection of the tracking results (compared to a
visual perception of individual fish passing through the beam).
The final DIDSON processing step involved one of two methods: fished tracking or density-
based passage estimation (Table 4.1-1). For low to moderately high passage rates (<20,000
fish/hr) fish tracking was used. Fish echo traces were tracked with Echoview’s implementation
of an α-β-tracking algorithm, which tracks systematic movement of the target. The purpose of
tracking is to group each series of echoes that has been returned by an individual fish. The total
number of detected fish tracks thus equals the number of fish observed over the time period
sampled. Tracking parameters (α, β, exclusion distance, weights and track acceptance criteria)
were empirically adjusted to provide the best tracking performance for a given set of data files.
Tracking results were exported and summarized in Excel. The number of fish tracked was
expanded in proportion to the time sampled to provide estimated passage rates (fish/hr).
At very high passage rates fish are so densely spaced that the tracking algorithm tends to join
adjacent fish, thus underestimating the total number of fish. The team therefore explored a
density-based approach as an alternative for high passage rates (>20,000 fish/hr). To assess the
accuracy of this alternative method the team examined a subset of the data, which spanned a
range of passage rates and for which the team had good track estimates. For the density-based
approach, fish passage was estimated as:
𝑝= ∑𝑥𝑛𝑖=1𝑛× 𝑤�𝑠̅× 3600
Where
𝑝 is the estimated number of fish per hour 𝑥 is the number of targets detected on frame i
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 5 June 2014
𝑛 is the number of good frames, i.e., frames that are not compromised by
noise or fish blocking the image 𝑤� is the width (m) of the examined field of view at the average range of all
targets detected in all good frames (in the given hour) 𝑠̅ is the average speed of a subset of fish tracked (m/s)
Splitbeam data were processed in Echoview 5.3. Data were edited to remove signals from the
river bottom (i.e., stationary line on echogram) and salmon-sized fish. The edited data were
analyzed with echo integration. Echo integration is a well-established fish quantification
technique that is based on the concept that the total amount of echo energy is proportional to the
density of targets in the ensonified volume of water (Simmonds and McLennan 2005). It is
typically used for down-looking mobile surveys of schooling fish. The same principle can be
applied to side-looking data.
Data were echo integrated with a -40 dB threshold, over cells spanning 1 hour periods and 5 m
range strata, to generate areal backscattering coefficients (i.e., an unscaled, relative measure of
fish density). To evaluate the echo integration results and determine an appropriate scaling
factor, the team examined the relationship between the areal backscattering coefficients and
density-based DIDSON estimates of data from a 4-day period (6/6 18:00 – 6/10 19:00) of high
passage (20,000 – 100,000 fish/hour) that was not compromised by spawning and milling
activity. The echo integration scaling factor was derived from the slope and intercept of a linear
regression through the paired data points (R2 = 0.6).
4.1.2. Active Fish Sampling
4.1.2.1. Standardized Dipnetting
Dip nets were used to collect eulachon in the lower Susitna River to (1) help verify species
composition and overall representativeness of fixed-station sonar results, (2) collect fish for radio
telemetry (Section 4.2.1), and (3) describe eulachon population characteristics (Section 4.4).
Sampling sites ranged from PRM 11.0 to PRM 19.2 (Figure 3.1-1).
Because of the extremely late ice break-up in 2013 (officially May 20 at Sunshine Creek, but ice
still covered most of the river upstream of PRM 15 on this date), limited opportunistic dip-net
sampling was conducted when possible prior to and during break-up to detect any early-running
eulachon. Sampling was conducted on May 9, May 20, May 22, and May 25 at a number of sites
between PRM 11 and PRM 17.5 where ice was absent. This early sampling was not
standardized; however, some sites were sampled on multiple days.
Standardized sampling was initiated on May 31 and initially was limited to the right bank at
PRM 17.5 and the left bank at PRM 17.7 to be near the fixed sonar station. At each site, a 10-m
by 20-m (32.8-ft by 65.6-ft) grid was established and divided into eight cells (5-m by 5 -m [16.4-
ft by 16.4-ft] each). Each cell was assigned a number and two cells at each site were randomly
selected to sample each day. Cells were fished by one or two dipnetters using standard eulachon
dip nets. Fishing duration often varied based on catch (high densities of eulachon sometimes
resulted in large catches in a short time).
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FERC Project No. 14241 Part A - Page 6 June 2014
Sampling near the right bank at PRM 17.5 continued to track with sonar estimates through the
end of the season, despite the presence of large aggregations of spawning eulachon early in the
season. Sampling was terminated on June 15 when catches diminished. Sampling on the left
bank at PRM 17.7 began June 1 and ceased after June 5 when this site also started being used by
eulachon for spawning.
To continue daily sampling at a site not being used for spawning, the site at PRM 17.7 was
replaced on June 6 by a site on the left bank at PRM 19.2. The bottom profile at this site was a
steep drop-off along a cut bank, in contrast to a gradual slope at PRM 17.5 and PRM 17.7, and
was not utilized by eulachon for spawning. A grid was not established at PRM 19.2, but a
standard location was sampled daily.
Sex was determined and fork length (nearest mm) was measured from a subsample of eulachon
captured each day throughout the run (Table 4.1-2). Otoliths were collected from a subsample of
fish daily. Stomachs of fish sacrificed for otolith collection were examined, with some retained
for subsequent analysis if not obviously empty. Fin clips for genetic analysis were also collected
from a subset of these fish. Other fish species captured were identified, counted, and measured.
Water temperature and water depth were recorded daily at each sampling location.
Beginning June 12, by which time catches at PRM 17.5 and PRM 19.2 had diminished, sites
downstream from PRM 17.5 were sampled to determine if eulachon were still entering the river,
and to identify potential sampling locations for the next year of study. Grids were not
established.
4.1.2.2. Data Summary and Analysis
Daily CPUE from non-spawning sites along the left bank of the river was calculated for
qualitative comparison of relative density to sonar findings. Species composition of the catch
was summarized at each sampling location, including length, weight, and sex ratios. Daily sex
ratios, mean length, and weight were also calculated to determine sex-specific differences, as
well as differences in the run over time.
Catches of non-eulachon species were documented and sex and length were recorded when
possible. Incidental catches of marine species were documented and measured for length (see
Section 4.4.3.1).
4.1.3. Variances from Study Plan
RSP Section 9.16.4.1.1 provided that the study team would construct a blocking weir around the
sonars to exclude eulachon from the 70–100 centimeter (27–39 inch) range in front of the sonar
face. Instead, the weir had to be removed for most of the sampling period because flood
conditions made it too difficult to keep the weir clean. It also appeared that ripples created
downstream of obstructions such as the weir tended to trigger the formation of spawning
aggregations. When flow conditions stabilized, useful information was collected by the sonar
without the weir in place and the study team was able to meet the objective of using the sonar to
develop indices of passage over time for migrating eulachon. Placement of the weir in the next
year of study will depend on flow conditions.
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RSP Section 9.16.4.1.3 provided that AEA would measure water velocity weekly at the fixed
sonar site. Water velocity measurements have been used as a surrogate for the swim speed of
downstream-migrating fish in conversions of density to flux (fish passing per unit time).
However, in the case of upstream migrating eulachon, using water velocity in the density-to-flux
conversion would not be appropriate. Because swim speed of individual eulachon as they were
moving through the beam could be tracked, no surrogate was needed, and thus the study team did
not collect water velocity measurements at the fixed sonar station. Indices of fish passage over
time were developed without the use of this data in accordance with Objective 1.This change will
continue in the next year of study.
RSP Section 9.16.4.1.2 provided that AEA would conduct standard sampling with dip nets
and/or gillnets to assess representativeness of results from the fixed sonar site. This sampling
was expanded in 2013 to include sampling before the fixed site could be installed due to ice and
flow conditions. Also, during the operation of the fixed site, fish sampling in 2013 was not
restricted to the fixed sonar station because that location became a spawning site. Other sites
where fish did not seem to be spawning, but were passing through, were sampled to more
effectively estimate run timing and CPUE. Study objectives to estimate run timing and passage
indices were still achieved, as all sampling supported evaluation of the representativeness of the
fixed sonar station results and the evaluation of run timing in the Susitna River. Sampling at
multiple sites will continue in the next year of study.
RSP Section 9.16.4.1.1 provided that AEA would collect sonar data at the fixed site until after
June 10, or no eulachon were detected at the fixed site, or during nearby sampling for five
consecutive days. Given the peak estimates of passage from sonar (>100,000 fish per day) and
CPUE (875 fish per minute of dipnetting), sampling for five consecutive days with zero catch
would have been costly and uninformative. Instead, AEA discontinued sampling after June 15,
by which time sonar detections had become minimal, and CPUE at PRM 17.5 had been below
two fish per minute for five consecutive days. Sampling at alternative (non-spawning) sites also
yielded less than two fish per minute on these days. Sampling in the next year of study will also
cease after CPUE is below two fish per minute for five consecutive days as described in Section
7.1.1.
4.2. Objective 2: Identification and Mapping of Potential Eulachon
Spawning Sites
Tasks to address Objective 2 included:
• Locating possible eulachon spawning sites using radio telemetry.
• Identifying likely eulachon spawning sites using multibeam sonar (DIDSON).
• Confirming the presence of spawning eulachon through active fish sampling methods.
• Mapping confirmed eulachon spawning sites.
Radio telemetry, visual observations, acoustics, and active fish sampling methods were used to
identify eulachon spawning sites. Radio telemetry was used to follow tagged fish throughout the
river, visual observations helped identify concentrations of fish, and acoustics were used to
document fish behavior. Eulachon were tagged in the Lower River and then tracked with aerial
surveys, using a similar approach to that described in Salmon Escapement Study, Section 9.7.
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Initial and final distributions of tagged fish were calculated using the same approach and
software as in the Salmon Escapement Study.
Prospective spawning sites were further investigated using a combination of multibeam sonar
(DIDSON) and active sampling. DIDSON sonar was used to obtain video-type images of
eulachon behavior and to observe fish passage at spawning sites. Fish sampling with dip nets
confirmed that detections were eulachon and allowed for assessment of spawning condition, fish
sex, and length.
4.2.1. Identifying Potential Spawning Locations Using Radio Telemetry
4.2.1.1. Fish Capture and Tagging, sample sizes
Eulachon to be radio-tagged were captured at different locations in the lower Susitna River to
increase the chance of tagged fish representing different potential run components. All eulachon
to be tagged were captured with a dip net constructed of 1/4-inch knotless nylon mesh with a 24-
inch deep bag (Model 3544 made by Frabill, S. Plano, IL). Eulachon to be tagged were selected
immediately upon capture and only tagged after found to be vigorous, free of obvious injuries,
and in pre-spawning condition (Spangler et al. 2003).
For each tagged eulachon, time of fish capture, tagging start time, and time of release back into
water were recorded. Each tagged eulachon was also measured for body length (nearest mm)
and classified for sex. Presence of gametes (milt or eggs) was used to verify fish had not
completed spawning. Fish processing time was considered the difference between the tagging
start time and final release into water, and recorded in seconds (Figure 4.2-1). To reduce
handling stress and aid recovery, fish were tagged as soon as possible after capture (not held and
tagged in batches), and returned to the water at a site with velocity shelter.
In total, 207 eulachon were radio-tagged in 2013 (Table 4.2-1). Based on a preseason power
analysis, a given spawning site containing 2.5 percent of the run would have a 97 percent
likelihood of receiving one tag from a release group of 150 tags. For sites with 5 percent of the
total run, this likelihood rises to >99 percent. The study team attempted to further increase these
likelihoods by tagging 50 additional eulachon (to account for potential tag loss) and by tagging at
different sites (to reduce the chance of over-tagging fish bound for only one area). It is important
to note that the goal of this study component was to identify locations of the main spawning
areas used in 2013.
Radio tags used were model MST-720, manufactured by Lotek Wireless Inc. (Newmarket,
Ontario). Tags measured 7-mm by 18-mm (0.28-inches by 0.71-inches), weighed 1.3 g (0.46
oz), and had an estimated 29-d battery life at a pulse rate of 4.0 or 4.5 seconds. Radio tag codes
were split evenly between two frequencies: 151.340 and 151.360 MHz. Tags were gastrically
implanted into the eulachon without anesthetic, following the methods used by Spangler et al.
(2003) when tagging eulachon on the nearby Twentymile River. Based on the 95 percent range
of fish weights sampled in 1982 and 1983 (ADF&G 1984; Vincent-Lang and Queral 1984), the
tag weighed 1.8 to 2.3 percent of the body weight of Susitna River eulachon.
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
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Tag retention and mortality were also assessed by comparing a test group of tagged and a control
group of untagged fish, each held for 48 hours in separate, adjacent totes submerged in the river.
The test group of 12 radio-tagged fish was held from June 10 to 12, 2013. The control group of
17 untagged fish was held from June 11 to 13, 2013. All fish were checked for mortality and tag
loss every 24 hours. An additional three radio-tagged fish were added to the test group for the
last 24 hours.
4.2.1.2. Aerial Survey Operation
Aerial surveys were flown on 12 dates in 2013 to track tagged eulachon, starting on May 31 and
ending on June 18 (Table 4.2-2). All surveys were conducted upstream of PRM 10 (the
electrical power line crossing the river), and typically covered 25 to 35 river miles in a day. By
mid-season, the spread of tag detection locations meant that two days were needed to survey
potential tag locations; these surveys were typically split at PRM 10 through PRM 46.5 on the
first day and from PRM 31 through PRM 57.5 on the second day. The Yentna River was
surveyed up to the Yentna fixed telemetry station, and the mainstem Susitna River was surveyed
to at least PRM 46.5 on all surveys (Table 4.2-2). All potential mainstem habitats (mainstem,
side channels, and sloughs) were flown, including the West Channel (into which Alexander
Creek drains), Kroto Slough, and several unnamed sloughs that are newly formed (Figure 4.2-2).
Aerial surveys ended following review of the data from the flight on June 18. This survey was
flown to check for any fish moving undetected upstream of the Willow fixed station, and had
complete coverage (including all side channels and sloughs) up to PRM 67, and partial coverage
(main channel) up to PRM 98 (Talkeetna). No tags were detected.
For all surveys, a 4-element yagi antenna was externally mounted to the helicopter’s skid racks,
then connected via coaxial cable and splitter to two Lotek SRX-400 telemetry receivers operated
by a biologist inside the helicopter. Each telemetry receiver was programmed to a single
frequency; receivers were monitored visually and via headphones. Tag frequency, tag code,
signal power, and time of detection were automatically recorded by the SRX-400 for each tag
detection, while the entire flight track was recorded with a global positioning system (GPS;
Garmin model 590). Early in the season, a second biologist also recorded tag detection
information in writing as backup to verify correct recording by the SRX-400. Radio detections
were time-stamped, then later synced to the GPS to record position. The first survey was flown
with a Robinson R44; all subsequent surveys were flown with a Jet Ranger. Surveys were
typically flown at an altitude of approximately 200 to 300 ft and at a speed of 50 to 60 knots
(kts). When a tag was detected, the area was re-flown with reduced speed and altitude lowered
to attain a more precise detection location. Gain was adjusted throughout the survey though was
typically 62 to 72. Radio interference in the lower river (likely originating from military
sources) necessitated the gain be lower in the lower river, especially on frequency 151.340 MHz.
Upstream of the confluence of the Deshka River, the gain was increased to extend survey
detection range.
4.2.1.3. Fixed Telemetry Station Operation
Fixed telemetry stations were established at three sites to help detect any tagged fish moving out
of the study area and to help guide aerial surveys. The first station (“Gateway”) was located at
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PRM 17.5, which was the most downstream constriction of the mainstem river and captured all
the river channel except for one side slough (Figure 4.2-2). The purpose of this station was to
help document tags and to detect tagged fish dropping down out of the study area. The station
was unable to fully serve this latter purpose because it could not simultaneously be located at the
bottom of the spawning and tagging areas and still be in a part of the river where it covered the
entire channel. The second fixed station (“Willow”) was located at PRM 52.5, and was the most
upstream station. The purpose of this station was to detect tags moving upstream of the expected
range of spawning. The third fixed station (“Yentna”) was 5.6 river miles up the Yentna River.
The purpose of this station was to detect any fish migrating out of the study area via the Yentna
River; the station needed to be as high up the Yentna River as it was because of a slough that
connects the Yentna and Susitna rivers (Figure 4.2-2).
Each fixed telemetry station consisted of a receiver (Lotek model SRX-400), a power supply (a
12-volt battery charged by a 50-watt solar panel), and one or two antennas. Fixed stations were
visited every 3–5 days to download tag data and maintain the station. One reference radio tag
(frequency 151.380 MHz) was kept at each fixed station to maintain a record of operation and
ensure that a lack of tag detections accurately reflected an absence of detectable tags. During
fixed station installation at the Gateway station, tags along the opposite bank of the river were
used to measure range of detectability and adjust gain settings. The resulting settings were used
at all fixed telemetry stations.
4.2.1.4. Data Summary and Analysis
Aerial survey data were processed briefly during the season, then more extensively after the
season. During the season, aerial survey data were imported into ArcGIS Explorer (ESRI,
Redlands, CA) and plotted to help guide in-season aerial and mobile sonar surveys for eulachon.
After the season, data were further analyzed to identify final destinations of tagged fish, which
were taken as the best indication of potential spawning locations.
In-season, the telemetry crew was able to guide mobile sonar crews to locations of radio tag
detections. After each survey, tag detections were discussed with the mobile sonar crew using
ArcGIS Explorer and maps, and GIS maps were created to identify areas to explore further.
During some surveys, the telemetry crew was also able to signal the mobile sonar crew when
multiple fish were detected nearby.
Postseason, Telemetry Assessor ™ (LGL Limited, Sidney BC) was used to screen all aerial tag
detections and identify the highest-power detection of each tag during a given survey. Data were
then imported into Microsoft Excel and visualized with ArcGIS Explorer. From there, tags were
filtered based on upstream movement after tagging, number of surveys detected, repeat
detections in the same location, and presence within clusters of other tags. All of these were
used to identify final destinations of tagged fish and thus potential spawning sites.
The migration behavior of individual fish was the first way potential spawning locations were
identified. Potential spawners were identified by filtering for only those fish detected upstream
of their original tagging site. Then, each aerial detection of these fish was placed into one of
three categories based on its movement since the previous detection: ascending for fish that had
moved upstream, descending for fish that had moved downstream, or static for fish that remained
within 500 m (1,640 ft) of their previous detection. The purpose of the static category was to
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allow some uncertainty before classifying a movement as ascending or descending. Locations
classified as descending were then removed from the analysis. The study team also removed
static locations that followed a descending detection, because these had an increased chance of
being carcasses. Potential spawning locations were considered to be the most upstream of the
ascending locations of each fish, plus any remaining location within 200 m (656 ft) of another
(by that same fish) on other surveys. The final list of these locations was plotted as the potential
spawning locations identified from the detection histories of individual fish.
The second approach to identifying potential spawning locations was based on spatial clustering
of detections from all pooled fish (instead of separate detection histories of individual fish). As
with the first approach, only fish detected upstream of their original tagging site were included.
Detections of these fish were then classified as ascending, descending, or static, and detections
that were descending and static following a descent were dropped from the analysis. All
remaining ascending or static locations were then plotted for all fish combined, and a 100-m
(328-ft) buffer was created around each point. All overlapping buffers were identified, and a
polygon was created to capture each group of overlapping points and their 100-m (328-ft)
buffers. The resulting polygon was considered a spawning cluster. Each spawning cluster was
numbered and assigned a position based on its geographic center. The number of fish in each
cluster and its location in the main channel or a side channel were reported. No attempt was
made to differentiate whether fish within these polygons were spawning or just holding.
4.2.2. Confirming Spawning Locations
4.2.2.1. Mobile Sonar Surveys
At potential spawning sites, a boat-mounted DIDSON imaging sonar (standard model) was used
to capture images of eulachon behavior. The DIDSON transducer was attached with an X2 dual
axis rotator on a pole mount that allowed easy deployment over the side of the boat (Figure 4.2-
3). The rotator provided control over the pan and tilt angle of the sonar. To have a sufficiently
stable platform, data were collected with the boat anchored or tied off onshore. DIDSON was
normally deployed for 10 minutes.
Depending on the physical characteristics of the site to be surveyed, the system was deployed in
one of two configurations. At sites where the riverbank had a gentle slope, eulachon were
typically spread out over several meters, which permitted observation with the DIDSON
mounted on the offshore side of the boat looking out toward the river. However, at steep cut
banks, the current typically forced eulachon to stay very close to shore (<1 m [3.28 ft]). In these
situations, to view eulachon at a sufficient range (>0.5 m [1.64 ft]), the DIDSON transducer was
lowered deep enough to aim back to shore underneath the hull of the boat. The rotator allowed a
quick move through 360° of pan and 90° tilt to find the optimum aim for viewing.
Data were recorded with DIDSON Viewer Version 5.25.43. The startup range and window
length were adjusted depending on the range interval where fish were seen; the frame rate was
set to the maximum the system was able to maintain. A minimum of 5 minutes of data were
collected at each site. All acoustic data were time-stamped and geo-referenced. Geo-referenced
analysis results were provided in a format compatible with ArcGIS.
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
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4.2.2.2. Fish Sampling
When acoustic surveys identified concentrations of fish that were likely to be spawning
eulachon, dip nets were used to confirm species identification and assess spawning condition.
Criteria from ADF&G (1984) were used to confirm spawning sites:
1. Fish captured at the site freely expel eggs or milt.
2. Fish are in vigorously free-swimming condition.
3. Twenty or more fish are caught that meet criteria 1 and 2 above.
Station ID, location, date, time, eulachon presence/absence, and a description of fish behavior
(i.e., moving in continuous band, discrete schools, milling, spawning) were collected at each site.
In addition, eulachon were sexed and measured for fork length (mm).
4.2.2.3. Data Summary and Analysis
All acoustic data were geo-referenced and time-stamped. For each site, a qualitative description
of fish behavior seen in the DIDSON footage was recorded, together with date, time, and
coordinates of the sample, and some example video clips. Length and sex ratio were summarized
for all fish caught during spawning site surveys and length was compared between sexes. Sex
ratio was also calculated at each site to determine site-specific differences over time. Locations
of confirmed spawning sites were compared to locations where radio telemetry tagged fish were
observed.
Post season, the identification of potential spawning areas using radio telemetry (both cluster and
individual sites) was assessed by examining how many areas in the Susitna River had been
assessed by mobile sonar and visual surveys, and whether spawning was confirmed. Telemetry
sites were considered to have been visited if surveyed to within 200 m. Conversely, the number
of spawning sites confirmed by sonar and visual surveys at which radio-tagged eulachon had not
been detected was summarized.
4.3. Objective 3: Eulachon Spawning Habitat Characteristics
Tasks to address Objective 3 included:
• Determining the feasibility of using acoustics to identify substrate composition at
eulachon spawning habitats:
o Estimating substrate composition using side scan sonar.
o Verifying accuracy using bottom grab samples and visual surveys.
• Describing physical characteristics of spawning habitats, including water quality
parameters, depth, and velocity.
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4.3.1. Feasibility of Acoustics to Determine Substrate Composition
4.3.1.1. Side Scan Sonar
A boat-mounted EdgeTech 4125 600/1600 kHz high-resolution side scan sonar was used to
provide images of the substrate and to test if it could detect migrating eulachon. Sites were
surveyed with the towfish deployed on a davit off the shore-side of the boat, with the boat
moving upstream, parallel to and approximately 20 m (65.6 ft) from the shoreline. Depending on
image quality, data were collected either in low or high frequency mode.
4.3.1.2. Grab Samples and Visual Surveys
An Ekman Bottom Grab Sampler and visual surveys were used to classify substrate at each
spawning site. Grab sampling was discontinued early because the sampler drifted downstream in
the current, even in low flows, such that a reliable substrate sample could not be collected.
Visual surveys were therefore the primary method used (Table 4.3-1). Overall substrate
composition was recorded based on substrate characterization protocols of the Instream Flow
Study (see RSP Section 8.5).
4.3.1.3. Data Summary and Analysis
Side scan data were reviewed in EdgeTech Discover 7.10. The fixed and time-varied gain of the
side scan images were adjusted to provide the best contrast over the range sampled. Images were
corrected for speed and slant range. Sites were categorized as sand or gravel based on their
similarity to images collected at three sites of known substrate composition (submerged sandbar,
sand waves, gravel).
Analysis of the side scan sonar data was limited to visual review, the preparation of sample
images, and a qualitative description of each site because little variation in substrate type was
found within sites. Preliminary acoustic substrate classifications were qualitatively compared to
classifications from visual surveys.
4.3.2. Physical Characteristics of Spawning Habitats
4.3.2.1. Water Quality and Physical Habitat
A YSI® meter for pH, water temperature, dissolved oxygen, and specific conductance was used
to assess water quality (Appendix Table A-1). Turbidity samples were collected in amber glass
vials and analyzed every evening with a Hatch Turbidimeter. Water quality data were collected
once at each spawning location for each survey (Table 4.3-1; Appendix Table A-2).
Aquatic habitat was recorded to the mesohabitat level based on the Project mesohabitat
classification system. Water depth at spawning locations was measured with a metric stadia rod
and water velocity was measured with a velocity flow meter (measured in feet per second).
Water depth and water velocity were collected at three randomized locations along the length of
the spawning habitat. Some spawning locations were not wadeable because of depth or current,
so water quality measurements were taken from the boat in these conditions.
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4.3.2.2. Data Summary and Analysis
Water quality parameters were summarized and compared among sites to facilitate description of
preferred water quality characteristics. Water velocity and depth at each site were averaged from
the three samples. Correlation analyses were used to evaluate the relationship between water
temperature and run timing.
4.3.3. Variances from Study Plan
RSP Section 9.16.4.3.3 provided that AEA may use a grid system for the collection of water
depth and water velocity data at confirmed spawning locations. At many sites, this was not
feasible because of swift current, precarious boat anchoring, or the inability to wade the area
safely (i.e., along a cut bank). Instead, these conditions necessitated that the study team collect
measurements directly from the boat and a grid design was not used to sample spawning site
water depth and water velocity. Depth and velocity measurements were taken at random from
three areas of each spawning site. This randomized sampling approach still allowed
characterization of spawning habitat in accordance with Objective 3 of the study, and will be
used again in the second year of study.
4.4. Objective 4: Eulachon Population Characteristics
Tasks to address for Objective 4 included:
• Determining present baseline population characteristics.
• Collecting baseline genetic samples.
• Documenting incidental observations of marine fish species.
Describing baseline population characteristics was a main focus on 1980s studies; however,
subsequent data indicate that population characteristics such as age may have changed since that
time (Shields and Dupuis 2012). Additional data were collected to establish current baseline
biological characteristics and archive genetic samples.
4.4.1. Baseline Population Characteristics
4.4.1.1. Fish Sampling
During active fish sampling to confirm presence of eulachon in the Lower Susitna River (Section
4.1), sex and spawning condition of all eulachon collected were documented. Fork length and
weight were measured, and otoliths were collected from a maximum of 30 pre-spawn eulachon
of each sex daily (Table 4.1-2). Stomach samples were collected from a subset of eulachon
retained for otolith extraction. Stomachs were evaluated for fullness, and then for diet if feeding
was suspected.
4.4.1.2. Data Summary and Analysis
Information on fork length, weight, and sex was used to build length and weight frequency
distributions by sex for migrating fish. Sex ratios were determined for each sampling day. Two-
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sample t-tests were used to determine differences in length and weight between male and female
eulachon.
Age data determined from otolith examination were used to assess age-length and age-weight
relationships, track age classes throughout the run, and determine sex-specific age differences.
Otoliths were aged following the protocol developed by Spangler et al. (2003) and Moffitt
(1999). Otoliths were viewed with a stereomicroscope attached to a computer monitor, allowing
several people to view otoliths at the same time. Otoliths were submerged in water to reduce
glare and placed on a black background to improve contrast between the translucent and opaque
zones. The age of fish was assigned by counting the translucent zones radiating out from the
primordium. At least two regions on the otoliths were counted, and if the counts from the first
two regions did not agree, a third was counted. If two of the three areas had the same count, this
became the assigned age; otherwise, the process was repeated. Three individuals read all of the
otoliths with the most common age assigned to each fish.
4.4.2. Baseline Genetic Samples
In support of the ADF&G’s development of genetic baselines for various species, genetic
samples from a subset of eulachon were collected (Table 4.1-2). Genetic samples consisted of
anal fin clips cut from the fish with scissors. Tissue samples were preserved in ethyl alcohol in a
125–500 ml (7.6–30.5 in3) bulk sample bottle for each site. Samples were delivered to the
ADF&G Gene Conservation Laboratory for archiving and potential future analysis.
4.4.3. Marine Fish Observations
4.4.3.1. Fish Sampling
Because walleye pollock (Theragra chalcogramma), yellowfin sole (Limanda aspera), saffron
cod (Eleginus gracilis), and Pacific cod (Gadus macrocephalus) are designated as primary
constituent element (PCE) species for CIBWs, their occurrence in the Susitna River is of special
interest to the Project for impact analyses. Marine fish caught while sampling for eulachon as
described in Section 4.1 were identified, and any fish in question were photographed for later
identification by a marine species expert. Marine fish were measured (either fork length or total
length [tip of the snout to tip of the caudal fin]; nearest millimeter).
4.4.3.2. Data Summary and Analysis
The Study Plan required that marine fish caught while sampling for eulachon as described above
and under Objective 1 would be identified, and any fish in question would be photographed and
identified later by a marine species expert. All marine fish would be measured (either fork length
or total length [tip of the snout to tip of the caudal fin]; nearest millimeter). Catch per unit effort
would be calculated for all fish species. All information regarding marine fish species presence
in the Lower Susitna River would be shared with the Fish Distribution and Abundance in the
Middle and Lower River Study (Section 9.6).
As noted below in Section 5.4.2, there were no marine fish observations in 2013.
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4.4.4. Variances from Study Plan
No variances to the Study Plan were implemented in 2013 for this objective.
5. RESULTS
Data developed in support of this study are available for download at
http://gis.suhydro.org/reports/isr:
5.1. Objective 1 – Eulachon Run Timing and Duration
5.1.1. Fixed Sonar
Information from fixed-station sonar (and from dipnetting) indicated that the bulk of the
eulachon run in the Susitna River occurred between May 28 and June 16 in 2013. The run
peaked between June 6 and June 8.
Acoustic data collection at the fixed site began on the evening of May 28 and ended the morning
of June 14. Data collection was temporarily impeded because of high water from June 1 through
June 4 (Figures 5.1-1 and 5.1-2). Continuous sampling with the stationary sonars resumed on
June 4 after the water level stabilized and began to recede. In addition, a high level of eulachon
milling and spawning activity between May 31 and June 5 precluded meaningful passage
estimates.
Even at very high passage rates (80,000 fish/hr), migrating eulachon were often sufficiently
spaced to resolve individual fish on the DIDSON images and derived echograms (Figure 5.1-3).
At low and moderately high densities (< 20,000 fish/hr) the echo traces tracked well (Figure 5.1-
4). Splitbeam data show a meandering band of migrating eulachon (Figure 5.1-5.). The time
series of the passage estimates (Figure 5.1-6) shows passage rates on the order of 1,000 fish/hr or
less toward the beginning and the end of the sampling period, which is two orders of magnitude
less than the passage rates observed June 6 through June 8 (approximately 40,000 – 100,000
fish/hr).
Comparison of the three types of acoustic estimates (track-based DIDSON, density-based
DIDSON, and echo integration splitbeam estimates) showed good agreement between the
methods over the overlapping range of passage rates for which they were suitable (Figures 5.1-7
and 5.1-8). The good match strengthens confidence in the estimates because each method is
sensitive to different types of error. The echo integration results are scaled based on a regression
against the density-based DIDSON estimates; however, the relative changes over time in the two
data series are independent.
5.1.2. Active Fish Sampling
Opportunistic sampling by dip net prior to ice break-up yielded only one eulachon. A female
was collected on May 25 at PRM 17.5. No fish were collected during sampling on May 9 (PRM
17.5), May 20 (PRM 10.5, PRM 14, and PRM 17.5), May 22 (three sites below PRM 15.0), or
May 25 (PRM 11.0, PRM 14.0, and PRM 16.0). Sampling consisted of one or two dip nets at
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each site. Effort at all sites combined was 15 minutes on May 9, 110 minutes on May 20, and
134 minutes on May 25.
Eulachon were sampled at the fixed sonar location (PRM 17.5), as well as at four supplementary
passage sites (PRM 11.0, 13.4, 17.7, and 19.2) on the left bank of the river from May 28 through
June 15 (Figure 3.1-1). A total of 2,344 eulachon were collected (Table 4.1-2). Four incidental
species were also caught, including undifferentiated lamprey, coho salmon, sockeye salmon, and
three-spine stickleback (Table 4.1-2). All salmon sampled were juveniles.
Catch at PRM 17.5, which eulachon used for spawning, fluctuated throughout the run and
exhibited a series of peaks (Figure 5.1-9). Eulachon daily CPUE at two non-spawning sites was
low (<1 fish/min) at the beginning and end of sampling, and peaked on June 7 with a CPUE of
250 eulachon/min (Figure 5.1-9). Trends in CPUE at these two sites tracked closely with trends
from the fixed station sonar. No correlation between run timing and water temperature was
observed (Figure 5.1-9); however, CPUE began to increase at water temperatures above 7˚C.
Stomachs were examined for all eulachon sacrificed for otolith collection; however, only 11
stomachs were collected for subsequent analysis. All stomachs observed were empty, flaccid,
and thread-like.
5.2. Identification and Mapping of Potential Eulachon Spawning
Sites
5.2.1. Radio Telemetry
5.2.1.1. Eulachon Capture for Radio-tagging
Fish were tagged each day from May 29 through June 15, 2013, at one of nine different sites
used over the course of the season. The number of tags placed daily was increased gradually
until the end of historical runs, after which daily tag placements decreased (Table 4.2-1). The
tagging team used a variety of information to assess run timing and guide tag placement: catch,
effort, and aerial observations of eulachon by the tagging team, communication with the
biosampling team, estimates of historical run timing, communication with fishery managers and
the consequence of ending the season with tags left over vs. running out of tags before the run
ended. Equal numbers of male and female eulachon were tagged on most days. In total, 207
eulachon were tagged (107 males and 100 females; Table 4.2-1). Tagging sites ranged from
PRM 11 to 19.5. Eight tagging sites were in the main channel and one was in a side channel
(Figure 4.2-2). All fish selected for tagging were vigorous, free of obvious injuries, and
appeared to be pre-spawning in that they still contained milt or eggs; these characteristics were
similar to those used by Spangler et al. (2003) when radio-tagging fish on the Twentymile River.
After tagging, each fish was inspected for proper tag placement and fish health before release,
discarding fish that appeared stressed or with a poorly seated tag. No tagged fish showed signs
of injury or tag regurgitation immediately after release. Mean tagging times were 42 seconds for
females and 38 seconds for males, with times decreasing as the tagger gained experience (Figure
4.2-1). Fish measuring approximately 210 to 220 mm (8.3 to 8.7 inches) were not tagged early
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in the season due to the difficulty of keeping the tag from being regurgitated, but began to be
tagged around June 5. One biologist tagged 203 of the 207 fish.
5.2.1.2. Tag Retention Testing
Tag retention and tagging effects were evaluated from June 10 to 13, 2013, using eulachon
captured in the West Channel. All eulachon evaluated were captured approximately 500 feet
downstream of site H5 and carried in buckets to the holding site. Eulachon were tagged
identically to procedures during normal operations using the same tags and application
procedures, with the exception of a longer transport (causing a longer period of time between
capture and release). Sometime on June 9 or 10, fish became scarce in the West Channel and on
June 10 most remaining fish had spawned. All fish used in the control group were thus spawned
out, and unspawned fish in the test group appeared even more gravid than fish tagged to date in
the main study.
Initially, 12 fish were used for the test (tagged) group starting on June 10. After 24 hours, this
group was checked for mortality and tag retention, and another 3 tagged fish were added. The
first group of 12 fish had one mortality and one tag regurgitation after 24 hours, then an
additional three mortalities after 48 hours. The additional group of three fish all survived and
retained their tags for the 24 hours tested.
The 17 fish in the control (untagged) group were held for 48 hours starting on June 11, with one
check each 24 hours. Of these fish, 9 died after 24 hours and another two died after 48 hours.
5.2.1.3. Eulachon Tracking using Radio Telemetry
Of the 207 tagged fish released, 159 were detected during aerial surveys. Of these 159 fish, 125
moved at least 500 m (1,640 ft) upstream after tagging and were thus considered potential
spawners. Tagged fish were detected during aerial surveys between PRM 10 and 44.5 in the
mainstem Susitna River, and 3.5 miles up the Yentna River. For the remaining fish, it was
impossible to determine the difference between downstream-moving spawners and any sulking
or injured fish.
5.2.1.4. Fixed Telemetry Stations
The Gateway fixed telemetry station collected data from May 29 through June 10 and from June
13 through June 25. The station collected partial data on June 9 and 10. In total, 109 unique tags
were detected at the Gateway fixed telemetry station. Ascending, descending, and stationary fish
were detected.
The Willow fixed telemetry station collected data from June 6 through June 26, near PRM 57.5
on the mainstem river right bank. This station operated continuously with no known outages,
and detected no tags.
The Yentna fixed telemetry station operated from May 31 through June 18, 2013, with no known
outages. At this fixed station, four unique tags were detected, likely moving upstream and out of
the study area. Of these four tags, two were not seen on subsequent aerial surveys and thus the
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fish likely spawned and died upstream of the Yentna fixed telemetry station. The remaining two
tagged fish were later detected in the mainstem Susitna River during aerial surveys.
5.2.1.5. Identification of Potential Spawning Sites Using Radio Telemetry
A total of 130 potential spawning sites were identified using the individual detection history
approach. These included one site from each of the 125 eulachon detected upstream of its
tagging site, along with a possible second location for 5 of these fish. Five of the sites,
representing five different fish, were in the Yentna River downstream of the Yentna fixed
telemetry station. The remaining 125 sites, representing 120 different fish, were in the mainstem
Susitna River and side channels (Figures 5.2–1a and b).
When these individual detections were integrated among all fish, the team identified 27 different
clusters of ascending or static eulachon. All clusters were in the mainstem Susitna River or side
channels, ranging from PRM 11.5 to PRM 29.7 (Figures 5.2-1a and b). Each cluster was
composed of two to five individual tagged eulachon, except for one cluster of 11 tagged
eulachon (Table 5.2-1). Of the 130 sites identified using individual detections, 79 sites made up
these clusters.
5.2.2. Confirming Spawning Locations
Twenty-eight spawning locations were confirmed from PRM 10.5 to 50.3 during mobile acoustic
and visual surveys. Spawning sites were easily identified by large aggregations of eulachon and
confirmed by the presence of males and females in spawning condition sampled with dip nets
(Tables 5.2-2 and 5.2-3; Appendix Table A-3). Males were more numerous at 18 of 28 sites
sampled (Table 5.2-3). Males were more often observed in spawning condition than females; the
proportion of females found in spawning condition increased as the season progressed (Table
5.2-3). Length for all fish sampled ranged from 187 to 247 mm (7.4 to 9.7 inches) (Table 5.2-4).
Females were statistically smaller (p<0.001) than males at all spawning sites (Table 5.2-4 and
Figure 5.2-2). No spawning was observed at three additional sites surveyed late in the season to
assess fish presence.
5.3. Eulachon Spawning Habitat Characteristics
5.3.1. Feasibility of Acoustics to Determine Substrate Composition
Substrate type identified through visual surveys matched well to that identified by side scan
sonar at all spawning sites (Appendix Table A-4). Side scan imagery showed differences
between primarily sand/silt substrate river bottom and primarily gravel substrate (Appendix B).
The brightness of the images distinguished between the soft, acoustically absorbent bottom
indicative of sand/silt in contrast to a very bright, reflective bottom indicating harder, larger
particle substrate. Photographs of the shoreline further confirmed the accuracy of side scan sonar
in identifying substrate (Appendix C).
5.3.2. Physical Characteristics of Spawning Habitat
Twenty-eight spawning sites were surveyed from May 29 through June 13 (Figure 5.3-1).
Overall spawning site characteristics included shallow water (<1 m (3.3 ft)), slow current (<1
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m/s (3.3 ft/s)), and sandy/silty substrate (Table 5.3-1). Eulachon spawned at sites that were either
entirely composed of silt/sand substrate, or were a mixture of various sizes of gravel/cobble and
silt/sand (Appendix Table A-4). Water temperatures ranged from 5.2 to 10.29 ºC (41.4 to 50.5
ºF), with the warmest temperatures found during the latter part of the spawning season
(Appendix Table A-2). Ranges for specific conductance and pH were relatively small, but
dissolved oxygen and turbidity values fluctuated greatly (Table 5.3-1) and were site-specific.
5.4. Eulachon Population Characteristics
5.4.1. Baseline Population Characteristics
A total of 2,344 eulachon were sampled from sites located at PRM 11.0, 13.4, 17.5, 17.7, and
19.2 (Table 4.1-2). Males were more numerous than females and composed 54 percent of the
catch; the overall male to female (M:F) sex ratio was 1.2:1.0 (Table 5.4-1). Sex ratio varied
daily, and was nearly equal on June 6; however, males were more numerous for the duration of
the season (Table 5.4-2). Lengths and weights for eulachon differed between sexes (Figures 5.4-
1 and 5.4-2; Table 5.4-3). Male eulachon were longer at each age than females (Figure 5.4-3) but
heavier than females at age 2 only.
Assigned ages based on examination of 272 otoliths ranged from 2 to 4 years (Table 5.4-4). The
most common age class for both sexes was 3-year-olds, comprising nearly 68 percent of the
catch. The proportion of 3-year-old males and females was similar; however, females were more
often age 2. Both 3- and 4-year-old eulachon were numerous throughout the run (Figure 5.4-4).
No 5-year-old eulachon were observed. No timing differences among age classes were observed,
though there was a small peak of 4-year-olds on June 3.
5.4.2. Marine Fish Observations
No marine fish were observed.
6. DISCUSSION
6.1. Eulachon Run Timing and Duration
Despite the challenging river conditions, the beginning and the end of the run were captured and
a sufficient amount of moderate and high passage data were recorded to confirm the feasibility of
using sonar to estimate eulachon passage timing and duration. The three types of acoustic
passage estimates (track based DIDSON, density based DIDSON, echo integration splitbeam)
were in good agreement over the overlapping range of passage rates for which they are suitable.
Each of the three methods is sensitive to different types of error; therefore, the good match
increases confidence in the acoustic estimates. In addition, estimates of CPUE and run timing
from dipnetting efforts matched well to estimates of fish passage calculated from splitbeam and
DIDSON sonars.
The two-part run timing documented in previous studies (ADF&G 1984) could not be confirmed
in 2013, although catches in dip nets at the fixed station sonar did have multiple peaks (Figure
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6.1-1). Dip-net catches at this spawning site were subject to wide variation resulting from
differences in fish behavior (milling, spawning, etc.) at any given time and specific location
within the site. Catches at non-spawning sites did not exhibit a bi-modal appearance. Lack of
acoustic data during a period of challenging environmental conditions may have precluded
detection of two peaks in the eulachon run if these peaks occurred. If the run did lack two peaks,
this may have been due to compressed run timing resulting from the late spring break-up. Lack
of fish collected during opportunistic sampling prior to break-up reduces the likelihood that an
early peak occurred prior to intensive sampling.
Observations made by ADF&G fishwheel crews located at PRM 33.5 support the contention that
a late run of eulachon did not occur in 2013. Crews did not observe a second pulse of eulachon.
Although migrating fish were observed as late as June 20, sightings were infrequent and included
very small numbers (personal communication, Richard Yanusz, ADF&G).
Eulachon utilized a number of sites for spawning in 2013, including both sites initially selected
to be sampled to collect migrating fish for confirmation of sonar findings and to obtain
information on eulachon population characteristics. New sampling locations were established
mid-season to allow collection of data on eulachon that were migrating, but not spawning.
6.2. Identification and Mapping of Potential Eulachon Spawning
Sites
6.2.1. Radio Telemetry
The range of potential spawning locations identified by radio telemetry in 2013 matches
relatively well with spawning distribution documented in the 1980s. In 2013, potential sites
were as low as the study design would allow (~PRM 11.0) and as high as PRM 44.5. These
appear similar to the range of historic river miles 8.5 to 50 reported in the 1980s (ADF&G 1984;
Vincent-Lang and Queral 1984; personal communication from M. Bourdon, LGL GIS analyst,
August 20, 2013). As in the 1980s, the team detected no potential sites upstream of Willow
Creek in 2013, and the majority (117 of 130) was downstream from the Yentna River
confluence. As in the 1980s, some eulachon moved into the Yentna River, including some that
spawned in the lower section and others that moved higher up the Yentna River, out of the study
area (ADF&G 1984; Vincent-Lang and Queral 1984).
The 125 radio-tagged fish used to identify potential spawning sites should be considered a
minimum number of viable tags, a result of filtering to include those fish likely to give the most
reliable information. Another 34 fish were detected but not used because they did not ascend the
500 m (1,640 ft) needed to qualify as an upstream movement. Some of these fish likely spawned
within 500 m (1,640 ft) of their tag site based on how much spawning activity was documented
in the reaches used for tagging.
Potential sites identified from radio telemetry in 2013 should also be considered a conservative
estimate because the detections were filtered to include those most likely to represent spawning
fish, and because the study team was restricted from sampling downstream from PRM 10 in
2013 to avoid potential harassment of Cook Inlet beluga whales. It is possible that some of the
unused ascending and static tag detections included spawning fish mixed in with post-spawning
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fish and that some fish spawned downstream from PRM 10 before ever ascending upstream far
enough to be tagged.
Radio detections indicate that eulachon migration and spawning behavior in the Susitna River
may be more complex than directed linear movements to a spawning site. For example, one fish
travelled over 20 miles up the Susitna River after tagging, and then dropped downstream and
migrated up the Yentna River. Other eulachon were found twice in places identified as potential
spawning sites for other fish, then migrated upstream to another potential spawning site. It is
possible these detections represented two spawning events by one individual. Willson et al.
(2006) report that individual eulachon may spawn more than once in a lifetime, but note that
iteroparity (multiple reproductive events) is not well understood.
Radio telemetry proved to be a viable method for studying Susitna River eulachon. All eulachon
tagging sites were on or near spawning sites, so many tagged fish may have had little or no
reason to migrate upstream. Despite this, over half the eulachon moved greater than 500 m
(1,640 ft) upstream after tagging and many of those moved over 20 km (12 miles). The study
team also detected no major issues with tagging females vs. males, addressing a possible concern
raised by Spangler et al. (2003) during telemetry studies on the Twentymile River.
The tag retention study provided only modest insight into tag retention and tagging effects
because the only fish found near the holding site were noticeably less hardy than fish chosen for
tagging. As evidence, there were more mortalities in the control group (11 of 17 untagged fish)
than in the test group (4 of 15 tagged fish), suggesting that fish were simply too sensitive to
handle at that point.
6.2.2. Mobile Sonar Surveys
The distribution of spawning sites confirmed by mobile sonar and visual surveys also matched
well to that found by ADF&G (1984), and in some cases overlapped completely, indicating that
eulachon may have some site fidelity over time. Sites ranged from historic RM 4.5 to 50.5 in
1984, compared to PRM 10.5 to 50.3 in 2013. Only 28 spawning sites were confirmed in 2013,
whereas ADF&G (1984) found 57 sites. Most historical and current sites were located
downstream from the Yentna River confluence, suggesting that eulachon may prefer habitat in
this area.
6.3. Eulachon Spawning Habitat Characteristics
Early on, in the extremely muddy floodwater, the low-frequency side scan sonar mode provided
good images of substrate because of the lower absorption compared to high frequency. As the silt
load of the river started to decrease, the high-frequency mode was able to image the entire range
sampled and high frequency became the mode of choice because it produced images with a
higher resolution.
Although side scan sonar provided good images of substrate, visual surveys and side scan sonar
output files produced similar substrate classifications for all sites. Side scan sonar was able to
successfully distinguish between gravel and sand substrate, and in a few cases was able to
provide information not obtained through visual assessments (i.e., gravel bar at base of cut bank).
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In those cases, the fish were spawning along the cut bank, and not the submerged gravel bar.
Side scan sonar is a useful tool to observe differences in river bottom topography; however,
visual surveys obtained the same information where fish were actively spawning. Visual surveys
should therefore be the primary method for characterizing substrate at spawning sites in the
second year of study; however, side scan sonar may prove useful if any spawning sites are found
at depths too great to be surveyed visually.
Spawning sites surveyed during this study were similar to those found by ADF&G (1984) in
substrate type, velocity, and depth. Eulachon seemed to follow near-shore currents and prefer
habitats with moderate flow (less than 1 m/s [3.3 ft/s]), spawn on mostly sand/silt substrate or
mixed gravel, and in water less than 1 m (3.3 ft) deep. Crowding mortality occurred at almost
every spawning site surveyed, particularly later in the season as more fished moved into areas
where fish had previously spawned. This was exacerbated at very shallow sites where dead fish
that had not yet spawned littered the shoreline.
6.4. Eulachon Population Characteristics
Eulachon age class composition was similar to that found by ADF&G (1984) in the 1980s; 3-
year-olds were the dominant age class, followed by 4-year-olds. Mean length and weight of
eulachon sampled during this study were larger than for eulachon sampled in 1984. Sex ratios
were also similar, as males were the dominant sex. Males were more frequently observed in
spawning condition than females, perhaps indicating that males mature earlier and remain in
spawning readiness longer than females.
6.5. Relationship to Other Studies
The eulachon study is interrelated with a number of other studies (Baseline Water Quality –
Study 5.5; Water Quality Modeling – Study 5.6; Geomorphology – Study 6.5; Fluvial
Geomorphology – Study 6.6; Ice Processes – Study 7.6; Fish and Aquatics Instream Flow –
Study 8.5; Salmon Escapement – Study 9.7; and CIBW Study – Study 9.17). In some cases,
information from other studies was used to help guide 2013 efforts. In other cases, collaboration
with related studies will begin in the second year of study.
7. COMPLETING THE STUDY
[Section 7 appears in the Part C section of this ISR.]
8. LITERATURE CITED
ADF&G (Alaska Department of Fish and Game). 1984. Susitna Hydro Aquatic Studies Report
No. 1: Adult Anadromous Fish Investigations May–October, 1983. Anchorage, Alaska.
AEA. (Alaska Energy Authority). 2011. Pre-application document: Susitna-Watana
Hydroelectric Project, FERC Project No. 14241. December 29, 2011.
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
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AEA. 2012. Revised Study Plan: Susitna-Watana Hydroelectric Project FERC Project No.
14241. December 2012. Prepared for the Federal Energy Regulatory Commission by the
Alaska Energy Authority, Anchorage, Alaska. http://www.susitna-
watanahydro.org/study-plan.
Moffitt, S. 1999. Commercial Fisheries. Alaska Department of Fish and Game. 7 p. Cordova,
Alaska.
Simmonds, J. and McLennan, D. 2005. Fisheries Acoustics: Theory and Practice. 2nd Ed.
Blackwell Science Ltd., Oxford, UK.
Shields, P. and Dupuis, A. 2012. Upper Cook Inlet commercial fisheries annual management
report, 2011. Alaska Department of Fish and Game, Fishery Management Report No. 12-
25, Anchorage.
Spangler, E.A.K, Spangler, R.E., and B.L. Norcross. 2003. Eulachon subsistence use and
ecology investigations of Cook Inlet. USFWS Office of Subsistence Management,
Fisheries Resources Monitoring Program, Final Report No. 00-041, Anchorage, Alaska.
Vincent-Lang, D. and I. Queral. 1984. Susitna Hydro aquatic studies. Report 3: Aquatic habitat
and instream flow. Chapter 5: Eulachon spawning habitat in the Lower Susitna River.
Willson, M. F, R. H. Armstrong, M. C. Hermans, and K Koski. 2006. Eulachon: a review of
biology and an annotated bibliography. AFSC Processed Report 2006-12. NMFS, Juneau
AK.
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9. TABLES
Table 4.1-1. Methods used in 2013 for processing acoustic data collected at the fixed sonar station (Project River Mile
17.5).
Data Characteristics
DIDSON Splitbeam
Fish tracking Density based Echo integration
Strengths
Independent of fish
speed;
Provides information
on direction of
movement.
Can handle higher
densities than fish
tracking.
Can handle higher densities than
density-based estimation;
Does not require individual fish to
resolve on the echogram.
Limitations
Breaks down when
fish density is too
high because the
tracks of adjacent
fish are more likely to
be joined.
Requires
information on fish
speed;
Requires individual
fish to resolve on
the image.
Requires scaling factor (e.g.
derived from comparison with
density-based estimates)
More error at low densities;
Presence of salmon inflates echo
integration based estimate more
than the other two methods.
Suitable passage rates
(fish/hr in 5 m range
interval)
< 20,000 < 100,000
20,000 - > 100,000
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Table 4.1-2. Total number of fish by species sampled at dipnetting sites from Project River Mile 11.0–19.2 in 2013.
Eulachon Incidental Catch
Date No.
collected
No.
weighed/
measured
No. radio
tagged
No.
otolith
samples
No.
stomach
samples
No.
genetic
samples
Lamprey (spp)
Coho salmon
(Oncorhynchus
kisutch)
Sockeye
salmon
(Oncorhynchus
nerka)
Three-spine
stickleback
(Gasterosteus
aculeatus)
May 31 828 738 10 53 11 61 0 1 0 2
June 1 67 67 10 20 0 20 0 0 0 1
June 2 217 217 10 19 0 20 1 0 0 0
June 3 200 200 10 20 0 20 0 0 0 2
June 4 166 166 14 20 0 20 0 0 0 25
June 5 165 156 14 20 0 20 0 0 5 15
June 6 168 93 14 15 0 15 0 0 0 43
June 7 142 142 16 15 0 15 0 0 0 1
June 8 139 139 10 10 0 10 0 0 0 0
June 9 123 123 20 10 0 10 0 0 0 0
June 10 32 32 14 8 0 8 0 0 0 1
June 11 25 25 14 9 0 9 0 0 0 1
June 12 40 40 14 11 0 11 0 0 0 1
June 13 15 15 10 13 0 13 0 0 0 1
June 14 16 16 5 15 0 11 0 0 2 2
June 15 1 1 2 14 0 1 0 0 0 1
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Table 4.2-1. Daily tagging locations, numbers, and body sizes of male and female eulachon tagged with radio transmitters
in 2013.
Females Males Total
Date Tag Site Latitude Longitude n
Mean length (mm) SD length n
Mean length (mm) SD length n
May 29 H3 61.39087 -150.55200 3 225 7.2 3 231 1.0 6
May 30 H4 61.43192 -150.47890 7 228 6.6 7 224 5.7 14
May 31 H5 61.42680 -150.57963 6 222 7.5 4 227 2.8 10
June 1 H11 61.40823 -150.46727 5 227 8.0 5 225 1.6 10
June 2 H6 61.39640 -150.54680 5 228 5.4 5 225 5.1 10
June 3 H5 61.42680 -150.57963 5 224 4.9 5 223 5.0 10
June 4 H7 61.37352 -150.57295 7 226 6.3 7 228 8.1 14
June 5 H11 61.40823 -150.46727 7 225 4.8 7 226 5.9 14
June 6 H7 61.37352 -150.57295 7 226 5.4 7 226 2.9 14
June 7 H8 61.39520 -150.54868 8 228 7.1 8 230 7.2 16
June 8 H8 61.39520 -150.54868 5 228 1.7 5 228 4.8 10
June 9 H8 61.39520 -150.54868 10 222 4.5 10 228 6.2 20
June 10 H8 61.39520 -150.54868 7 219 6.6 7 227 8.4 14
June 11 H8 61.39520 -150.54868 7 222 2.8 7 225 5.0 14
June 12 H9 61.39422 -150.56020 7 223 5.4 7 226 3.9 14
June 13 H10 61.36550 -150.58837 3 214 2.5 7 224 5.2 10
June 14 H10 61.36550 -150.58837 0 NA NA 5 224 6.3 5
June 15 H10 61.36550 -150.58837 1 213 NA 1 227 NA 2
Total 100 224 6.3 107 226 5.6 207
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 28 June 2014
Table 4.2-2. Summary of aerial survey effort for telemetry component of Susitna River eulachon, 2013.
Survey Date Aircraft Start
APRM
End
APRM
Tags
detected
(n)
Running
total of tags
placed
Description
May 31 R44 10 46.5 24 30 Powerlines to Deshka Landing
Slough
June 2 Jet Ranger 10 46.5 36 50 Powerlines to Deshka Landing
Slough
June 4 Jet Ranger 10 46.5 58 74 Powerlines to Deshka Landing
Slough
June 6 Jet Ranger 10 46.5 55 102 Powerlines to Deshka Landing
Slough
June 8 Jet Ranger 10 46.5 62 128 Powerlines to Deshka Landing
Slough
June 9 Jet Ranger 31 57.5 17 148 Susitna Station to Willow Fixed
Station
June 11 Jet Ranger 10 46.5 75 176 Powerlines to Deshka Landing
Slough
June 12 Jet Ranger 31 57.5 18 190 Susitna Station to Willow Fixed
Station
June 14 Jet Ranger 10 46.5 58 205 Powerlines to Deshka Landing
Slough
June 15 Jet Ranger 31 57.5 1 207 Susitna Station to Willow Fixed
Station
June 17 Jet Ranger 10 46.5 46 207 Powerlines to Deshka Landing
Slough
June 18 Jet Ranger 46.5 66.5 0 207 Deshka Landing Slough to Kashwitna
River
a Running total of tags overestimates possible tag detections because it includes fish deceased or not in survey area.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 29 June 2014
Table 4.2-3. Spawning site acoustic surveys compared to potential sites identified from radio telemetry in 2013.
Distance from nearest potential site identified from radio telemetry
Spawning
site ID Latitude Longitude PRM
Sonar
evaluation and
active sampling
date
Active
Sampling
Method
Distance (m) Detection date
1 61.40717 150.46793 17.5 May 29 dip net 83 5-Jun
2 61.50188 150.55199 25.5 May 31 dip net 329 14-Jun
3 61.37842 150.51888 13.6 June 1 dip net 298 14-Jun
4 61.49334 150.57045 25.3 June 1 dip net 254 4-Jun
5 61.50088 150.57139 25.6 June 2 dip net 566 8-Jun
6 61.57277 150.42819 33.4 June 6 dip net 109 9-Jun
7 61.54682 150.53017 29.6 June 2 dip net 66 6-Jun
8 61.37302 150.57472 11.3 June 3 dip net 47 8-Jun
9 61.41581 150.46315 18.2 June 3 dip net 243 2-Jun
10 61.47063 150.51956 22.6 June 3 dip net 252 31-May
11 61.41152 150.46274 17.9 June 4 dip net 60 6-Jun
12 61.43274 150.47868 19.5 June 5 dip net 94 30-May
13 61.44718 150.48115 20.4 June 5 dip net 114 14-Jun
14 61.45693 150.49355 21 June 5 dip net 261 4-Jun
15 61.46864 150.50798 22.3 June 5 dip net 68 8-Jun
17 61.63331 150.36914 39.4 June 6 dip net 1,801 4-Jun
18 61.53751 150.54214 28.8 June 6 dip net 132 8-Jun
19 61.36883 150.59325 10.5 June 7 dip net 83 14-Jun
20 61.43238 150.48557 19.3 June 7 dip net 18 14-Jun
21 61.49193 150.57899 25.2 June 7 dip net 559 8-Jun
22 61.52616 150.56616 27.7 June 8 dip net 114 8-Jun
23 61.61289 150.36998 37.4 June 9 dip net 859 4-Jun
24 61.66857 150.31087 43.1 June 9 dip net 323 9-Jun
25 61.68623 150.30736 44.3 June 9 dip net 205 9-Jun
26 61.75748 150.25575 50.3 June 10 dip net 8,208 9-Jun
27 61.71187 150.27534 46.6 June 10 dip net 3,121 9-Jun
28 61.70347 150.28322 45.8 June 10 dip net 2,105 9-Jun
31 61.55201 150.49042 30.8 June 13 dip net 632 11-Jun
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 30 June 2014
Table 4.3-1. Summary of spawning site habitat mapping effort in 2013.
Site ID Date Time PRM
Maximum Mainstem Flow (cfs) Survey Method YSI Data
Turbidity grab sample Depth & Flow
1 May 29 14:00 17.5 68,400 side scan sonar, visual survey yes yes yes
2 May 31 15:00 25.5 80,300 side scan sonar, visual survey no no yes
3 June 1 10:30 13.6 86,400 side scan sonar, visual survey yes yes yes
4 June 1 14:08 25.3 86,400 side scan sonar, visual survey yes yes yes
5 June 2 12:55 25.6 86,600 side scan sonar, visual survey yes yes yes
6 June 2 11:00 33.4 45,800 side scan sonar, visual survey yes no yes
7 June 2 15:17 29.6 86,600 side scan sonar, visual survey yes yes yes
8 June 3 12:35 11.3 74,600 side scan sonar, visual survey yes yes yes
9 June 3 14:29 18.2 74,600 visual survey yes yes yes
10 June 3 15:17 22.6 74,600 side scan sonar, visual survey yes yes yes
11 June 4 12:00 17.9 57,200 visual survey yes yes yes
12 June 5 11:20 19.5 53,800 side scan sonar, visual survey yes yes yes
13 June 5 12:20 20.4 53,800 side scan sonar, visual survey yes yes yes
14 June 5 13:00 21.0 53,800 side scan sonar, visual survey yes yes yes
15 June 5 13:50 22.3 53,800 side scan sonar, visual survey yes yes yes
17 June 6 12:54 39.4 45,800 visual survey yes no no
18 June 6 16:30 28.8 45,800 side scan sonar, visual survey yes yes yes
19 June 7 10:15 10.5 39,400 side scan sonar, visual survey yes yes yes
20 June 7 13:15 19.3 39,400 visual survey yes yes yes
21 June 7 14:21 25.2 39,400 side scan sonar, visual survey yes yes yes
22 June 8 12:48 27.7 41,200 side scan sonar, visual survey yes yes yes
23 June 9 11:14 37.4 43,400 visual survey yes yes yes
24 June 9 12:53 43.1 43,400 side scan sonar, visual survey yes yes yes
25 June 9 13:40 44.3 43,400 visual survey yes yes yes
26 June 10 12:37 50.3 42,400 visual survey yes yes yes
27 June 10 13:22 46.6 42,400 side scan sonar, visual survey yes yes yes
28 June 10 14:18 45.8 42,400 side scan sonar, visual survey yes yes yes
31 June 13 12:34 30.8 33,000 visual survey yes yes yes
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 31 June 2014
Table 5.2–1. Number, group size, and location of potential clusters of eulachon identified by radio telemetry in the
Susitna River, 2013. WGS84 datum. Clusters located within a side channel were not assigned a project river
mile.
Cluster number Project river mile Latitude Longitude Number of fish Channel Type
Cluster1 11.5 -150.57558 61.37356 3 Mainstem
Cluster2 12.1 -150.56318 61.37857 2 Mainstem
Cluster3 13.4 -150.54655 61.39715 2 Mainstem
Cluster4 16.9 -150.47399 61.40080 3 Mainstem
Cluster5 14.8 -150.51801 61.40366 2 Mainstem
Cluster6 14.3 -150.53883 61.40374 11 Mainstem
Cluster7 17.1 -150.47066 61.40324 2 Mainstem
Cluster8 † -150.57219 61.43347 3 Side Channel
Cluster9 19.4 -150.48815 61.43295 2 Mainstem
Cluster10 20.9 -150.49126 61.45314 2 Mainstem
Cluster11 21.4 -150.49471 61.46017 2 Mainstem
Cluster12 † -150.53079 61.46355 2 Side Channel
Cluster13 21.9 -150.50057 61.46594 2 Mainstem
Cluster14 21.6 -150.48476 61.46556 2 Mainstem
Cluster15 22.3 -150.50968 61.46942 2 Mainstem
Cluster16 23.1 -150.53024 61.47310 4 Mainstem
Cluster17 22.6 -150.51276 61.47498 2 Mainstem
Cluster18 23.5 -150.54103 61.47646 4 Mainstem
Cluster19 24.0 -150.55433 61.48007 4 Mainstem
Cluster20 24.4 -150.56490 61.48268 2 Mainstem
Cluster21 24.4 -150.55574 61.48778 3 Mainstem
Cluster22 † -150.53082 61.49112 2 Side Channel
Cluster23 26.6 -150.57277 61.51160 2 Mainstem
Cluster24 27.9 -150.54632 61.52863 2 Mainstem
Cluster25 28.7 -150.54356 61.53352 3 Mainstem
Cluster26 29.2 -150.53298 61.53621 4 Mainstem
Cluster27 29.7 -150.52747 61.54610 5 Mainstem
Total 79
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 32 June 2014
Table 5.2-2. Location, date, and number of fish sampled at spawning sites from May 29–June 13, 2013.
Site ID
Date
Latitude
Longitude
Project River Mile
Sex of sampled fish
M F M:F ratio
1 May 29 61.407170 150.467930 17.5 31 35 0.89
2 May 31 61.50188 150.55199 25.5 5 6 0.83
3 June 1 61.37842 150.51888 13.6 5 19 0.26
4 June 1 61.493340 150.570450 25.3 12 13 0.92
5 June 2 61.500880 150.571390 25.6 16 8 2.00
6 June 2 61.57277 150.42819 33.4 17 8 2.13
7 June 2 61.546820 150.530170 29.6 19 7 2.71
8 June 3 61.37302 150.57472 11.3 15 10 1.50
9 June 3 61.415810 150.463150 18.2 18 8 2.25
10 June 3 61.47063 150.51956 22.6 19 6 3.17
11 June 4 61.41152 150.46274 17.9 10 15 0.67
12 June 5 61.432740 150.478680 19.5 7 18 0.39
13 June 5 61.447180 150.481150 20.4 15 10 1.50
14 June 5 61.456930 150.493550 21 16 9 1.78
15 June 5 61.46864 150.50798 22.3 17 8 2.13
17 June 6 61.63331 150.36914 39.4 11 14 0.79
18 June 6 61.53751 150.54214 28.8 22 3 7.33
19 June 7 61.36883 150.59325 10.5 20 5 4.00
20 June 7 61.43238 150.48557 19.3 13 12 1.08
21 June 7 61.49193 150.57899 25.2 16 9 1.78
22 June 8 61.52616 150.56616 27.7 21 4 5.25
23 June 9 61.61289 150.36998 37.4 14 11 1.27
24 June 9 61.66857 150.31087 43.1 16 9 1.78
25 June 9 61.68623 150.30736 44.3 10 15 0.67
26 June 10 61.75748 150.25575 50.3 6 11 0.55
27 June 10 61.71187 150.27534 46.6 17 9 1.89
28 June 10 61.70347 150.28322 45.8 17 8 2.13
31 June 13 61.552010 150.490420 30.8 4 2 2.00
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 33 June 2014
Table 5.2-3. Summary of spawning condition of eulachon sampled at each spawning site in 2013.
Males Females
SITE ID Date
Project River Mile
Pre-spawning Spawning Post
spawning
Pre-
spawning Spawning Post
spawning
1 May 29 17.5 0 31 0 25 10 0
2 May 31 25.5 0 5 0 6 0 0
3 June 1 13.6 0 5 0 19 0 0
4 June 1 25.3 0 12 0 6 7 0
5 June 2 25.6 0 16 0 1 7 0
6 June 2 33.4 0 17 0 0 8 0
7 June 2 29.6 0 19 0 6 1 0
8 June 3 11.3 0 15 0 3 7 0
9 June 3 18.2 1 17 0 2 6 0
10 June 3 22.6 0 19 0 1 5 0
11 June 4 17.9 0 10 0 6 9 0
12 June 5 19.5 0 7 0 7 11 0
13 June 5 20.4 0 15 0 4 6 0
14 June 5 21.0 0 16 0 2 7 0
15 June 5 22.3 0 17 0 2 6 0
17 June 6 39.4 0 11 0 3 11 0
18 June 6 28.8 0 22 0 0 3 0
19 June 7 10.5 0 20 0 2 3 0
20 June 7 19.3 0 13 0 3 8 1
21 June 7 25.2 0 16 0 4 5 0
22 June 8 27.7 0 21 0 0 4 0
23 June 9 37.4 0 14 0 5 6 0
24 June 9 43.1 0 16 0 4 5 0
25 June 9 44.3 0 10 0 5 9 0
26 June 10 50.3 0 6 0 1 10 0
27 June 10 46.6 0 16 1 1 8 0
28 June 10 45.8 0 17 0 2 6 0
31 June 13 30.8 0 2 2 0 2 0
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 34 June 2014
Table 5.2-4. Summary of length (mm) of eulachon sampled at each spawning site in 2013.
Sex Mean SD Minimum Maximum N
Male 226.6 ± 7.06 193 247 402
Female 219.8 ± 8.21 187 238 292
All fish 223.7 ± 8.31 187 247 694
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 35 June 2014
Table 5.3-1. Summarized water quality parameters collected at 28 spawning sites in 2013.
Water Quality Parameter Min Max Range Mean
DO (mg/l) 6.64 20.75 14.11 12.21
Conductivity (µscm) 41 90 49 63.14
Turbidity (NTU) 116 586 470 331.68
pH 5.87 7.59 1.72 6.7
Temperature (C°) 5.2 10.29 5.09 7.54
Depth (m) 0.15 1.5 1.35 0.42
Velocity (m/s) 0.05 0.72 0.67 0.48
Table 5.4-1. Sex ratio for all fish caught during dipnetting at sites from Project River Mile 11.0 to 19.2 from May 28–June
16, 2013.
Sex Number of fish Percent
F 1,107 45
M 1,327 54
U 13 1
Total 2,447 100
Overall M:F 1.20
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 36 June 2014
Table 5.4-2. Eulachon sex ratio (M:F) by date from fish caught during dipnetting at sites from Project River Mile 11.0-
19.2 in 2013.
Date Eulachon Males Females Undetermined M:F Ratio
May 31 828 446 384 1 1.16
June 1 67 31 37 0 0.84
June 2 217 96 121 1 0.79
June 3 200 114 88 0 1.30
June 4 166 80 111 0 0.72
June 5 165 65 115 0 0.57
June 6 168 102 103 6 0.99
June 7 142 85 58 0 1.47
June 8 139 108 31 0 3.48
June 9 123 91 32 0 2.84
June 10 32 25 8 0 3.13
June 11 25 25 0 1 25.00
June 12 40 32 8 1 4.00
June 13 15 9 6 1 1.50
June 14 16 16 3 1 5.33
June 15 1 1 0 1 --
Table 5.4-3. Mean lengths and weights for eulachon sampled during dipnetting at sites from Project River Mile 11.0-19.2
in 2013.
Length Weight
Sex Mean (mm) SD N Mean (g) SD N
M 217.38 30.18 1,234 82.24 14.24 554
F 212.95 27.15 1,008 76.06 14.33 389
All fish 215.39 28.99 2,258 79.69 14.59 943
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 37 June 2014
Table 5.4-4. Overall age composition for eulachon sampled at dipnetting sites from PRM 11 to 19.2 during 2013.
Age Sex Sample Size
Length (mm) Weight (g)
Range Median Range Median
2 M 3 189-225 219 60-80 70
3 M 80 187-238 223 40-100 80
4 M 44 215-241 228 65-100 80
2 F 15 165-219 198 30-60 35
3 F 93 200-233 220 58-100 80
4 F 37 202-250 224 60-100 80
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FERC Project No. 14241 Part A - Page 38 June 2014
10. FIGURES
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 39 June 2014
Figure 3.1-1. Map of eulachon project study area in 2013 from Project River Mile 0–60.
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FERC Project No. 14241 Part A - Page 40 June 2014
Figure 4.1-1. Acoustic equipment deployed at the fixed site on May 30, 2013 at Project River Mile 17.5.
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 41 June 2014
Figure 4.2-1. Processing time (seconds) by date for eulachon radio tagged in 2013.
0
10
20
30
40
50
60
70
80
90
100
27-May 30-May 2-Jun 5-Jun 8-Jun 11-Jun 14-Jun 17-JunTagging time (s) Date
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 42 June 2014
Figure 4.2-2. Map of radio telemetry area of study in 2013, showing location of fish tagging site and fixed
station telemetry receivers.
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AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 43 June 2014
Figure 4.2-3. DIDSON imaging sonar and X2 rotator deployed over the side of the boat in 2013.
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 44 June 2014
Figure 5.1-1. River discharge measured on the Susitna River at Susitna Station from May 28–June 17, 2013.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 45 June 2014
Figure 5.1-2. River height measured on the Susitna River at Susitna Station from May 28–June 17, 2013.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 46 June 2014
Figure 5.1-3. DIDSON images of eulachon passing upstream in 2013. Angle echogram (left), 15° subset of
background subtracted DIDSON image (center) and corresponding view of detected targets (right). Echo
traces progressing from red to blue indicate upstream moving fish. Dashed vertical line on the echogram
marks frame shown on DIDSON image
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 47 June 2014
Figure 5.1-4. Zoomed view of DIDSON angle echogram and corresponding fish tracks in 2013. Echo traces
progressing from red to blue indicate upstream moving fish. Each colored line represents a tracked fish.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 48 June 2014
Figure 5.1-5. Splitbeam echogram of eulachon passing the fixed sonar site (Project River Mile 17.5) in 2013.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION, AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 49 June 2014
Figure 5.1-6. Time series of track and density-based DIDSON estimates of eulachon passage at the fixed sonar site (Project River Mile 17.5) in 2013.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 50 June 2014
Figure 5.1-7. Comparison of track and density based DIDSON estimates of eulachon passage at the fixed
sonar site (Project River Mile 17.5) in 2013.
Figure 5.1-8. Comparison of density-based DIDSON and echo integration splitbeam estimates of eulachon
passage at the fixed sonar site (Project River Mile 17.5) in 2013.
0
10,000
20,000
30,000
11-Jun11-Jun11-Jun11-Jun11-Jun12-Jun12-Jun12-Jun12-Jun12-Jun12-JunFish/hr Date
Track based DIDSON estimate
Density based DIDSON estimate
0
20,000
40,000
60,000
80,000
100,000
120,000
6-Jun6-Jun6-Jun7-Jun7-Jun7-Jun7-Jun7-Jun7-Jun8-Jun8-Jun8-Jun8-Jun8-Jun8-Jun9-Jun9-Jun9-Jun9-Jun9-Jun9-Jun10-Jun10-Jun10-Jun10-JunFish/hr Date/Time
Density based DIDSON estimate
3-point running average of density based
DIDSON estimate
Echo integration splitbeam estimate
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 51 June 2014
Figure 5.1-9. Eulachon CPUE (fish/min) in 2013 by day at one spawning site (PRM 17.5) and two non-
spawning sites compared to daily water temperature at the fixed sonar site (PRM 17.5). PRM = Project River
Mile.
0
2
4
6
8
10
12
14
0
100
200
300
400
500
600
700
800
900
1000
31-May1-Jun2-Jun3-Jun4-Jun5-Jun6-Jun7-Jun8-Jun9-Jun10-Jun11-Jun12-Jun13-Jun14-Jun15-JunTemperature, C CPUE (fish/min) Date
PRM 17.5
PRM 17.7
PRM 19.2
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Figure 5.2 – 1a. Potential spawning sites of eulachon in the Susitna River in 2013, based on radio telemetry
detections, Map 1 of 2.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
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FERC Project No. 14241 Part A - Page 53 June 2014
Figure 5.2 – 1b. Potential spawning sites of eulachon in the Susitna River in 2013, based on radio telemetry
detections, Map 2 of 2.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
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FERC Project No. 14241 Part A - Page 54 June 2014
Figure 5.2-2. Length frequency by sex for eulachon sampled at 28 spawning sites from Project River Mile
10.5 to 50.3 in 2013.
0
20
40
60
80
100
120
140
180 185 190 200 205 210 215 220 225 230 235 240 245 250 255Number of fish Length (mm)
Females
Males
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FERC Project No. 14241 Part A - Page 55 June 2014
Figure 5.3-1. Location of historic eulachon spawning sites (blue) and spawning sites surveyed in 2013 (purple)
by Project River Mile.
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Figure 5.4-1. Length frequency by sex for eulachon sampled at the fixed site (Project River Mile 17.5) from
May 31–June 15, 2013.
Figure 5.4-2. Weight frequency by sex for eulachon sampled at the fixed site (Project River Mile 17.5) from
May 31–June 15, 2013.
0
50
100
150
200
250
300
160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245 250 255 260Number of fish Length (mm)
Males
Females
0
50
100
150
200
250
300
350
30 40 50 60 70 80 90 100 110 120 130Number of fish Weight (g)
Males
Females
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 57 June 2014
Figure 5.4-3. Length, age and sex of eulachon sampled at non-spawning sites, 2013. Boxes bracket the 25th
and 75th percentile length values. Hash mark in the middle of the box denotes the median length value. The
top of the vertical line indicates maximum values and bottom indicates minimum values.
160
170
180
190
200
210
220
230
240
250
260
Age 2 Female Age 2 Male Age 3 Female Age 3 Male Age 4 Female Age 4 MaleLength (mm) Age and Sex
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page 58 June 2014
Figure 5.4-4. Ages of eulachon caught per day during sampling near the fixed site from May 31-June 15,
2013.
Figure 6.1-1. Eulachon run timing in 2013 from the fixed station as compared to counts from 1982 and 1983
studies.
0
5
10
15
20
25
30
35
31-May1-Jun2-Jun3-Jun4-Jun5-Jun6-Jun7-Jun8-Jun9-Jun10-Jun11-Jun12-Jun13-Jun14-Jun15-JunNumber of fish Date
2
3
4
0
500,000
1,000,000
1,500,000
2,000,000
10-May12-May14-May16-May18-May20-May22-May24-May26-May28-May30-May1-Jun3-Jun5-Jun7-Jun9-Jun11-Jun13-Jun15-JunFish/day Date
Estimate from fixed sonar 1982 1983 Peaks 1983
No estimates
Fish milling/
spawning
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 June 2014
PART A - APPENDIX A: EULACHON SPAWNING HABITAT TABLES
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix A – Page 1 June 2014
Appendix Table A-1. Summary of water quality probe specifications in 2013.
Parameter Instrument Units Range Accuracy Precision
Temperature YSI ˚C 0-85 ±0.2 ˚ 0.01 ˚
Dissolved oxygen YSI mg/L 0-50 ±0.2 0.01
pH YSI 0-14 ±0.2 0.01
Specific conductance YSI us/cm 0-200 ±0.5% 0.01
Water velocity Marsh-McBirney Flo-Mate m/s -0.5 - 20 ±2% --
Turbidity Hach 2100P Turbidimeter NTU 0-1000 -- 0.01
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix A – Page 2 June 2014
Appendix Table A-2. Instantaneous water quality parameters and water depth at spawning sites sampled from May 28–June 13, 2013.
Site ID
Project River Mile
Dissolved Oxygen (mg/l)
Specific conductance (µscm) Turbidity (NTU) pH Water Temp (C°) Water Depth (m) Velocity (m/s)
1 17.5 15.50 52 554 6.75 5.64 0.50 0.38
2 25.5 16.94 41 367 6.88 5.72 0.30 0.43
3 13.6 11.10 48 314 6.10 6.02 0.22 0.43
4 25.3 18.50 43 506 6.60 5.98 0.22 0.59
5 25.6 20.75 47 500 6.40 5.61 0.85 0.22
6 33.4 11.48 58 Not
recorded 7.48 6.46 0.25 0.55
7 29.6 12.77 74 536 6.67 7.51 0.60 1.00
8 11.3 14.75 56 746 6.75 5.20 0.23 0.65
9 18.2 9.45 51 495 6.06 5.28 0.46 0.28
10 22.6 13.05 69 586 6.85 5.83 0.28 0.46
11 17.9 12.15 58 346 5.87 6.42 0.20 0.35
12 19.5 14.45 58 316 6.30 6.49 0.25 0.50
13 20.4 11.80 58 340 6.40 6.65 1.50 0.45
14 21 11.43 76 270 6.49 7.28 0.46 0.54
15 22.3 12.30 78 308 6.46 7.53 0.48 0.71
17 39.4 13.15 58 Not
recorded 6.56 6.73 Not
recorded
Not
recorded
18 28.8 11.52 62 305 7.07 7.33 0.75 0.53
19 10.5 9.23 71 116 6.67 8.27 0.23 0.55
20 19.3 10.71 85 171 6.76 8.90 0.30 0.44
21 25.2 9.10 90 233 7.02 9.05 0.22 0.52
22 27.7 7.15 78 263 6.93 9.81 0.23 0.54
23 37.4 10.97 71 143 7.29 8.96 0.46 0.61
24 43.1 10.08 62 117 6.88 9.00 0.15 0.72
25 44.3 6.64 78 206 7.59 10.11 0.35 0.56
26 50.3 12.50 69 251 7.56 10.01 0.75 0.15
27 46.6 11.98 49 148 6.32 9.29 0.40 0.43
28 45.8 11.84 55 155 6.18 9.73 0.30 0.43
31 30.8 13.90 73 Not
recorded 6.71 10.29 Not
recorded 0.05
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix A – Page 3 June 2014
Appendix Table A-3. Summary of 2013 spawning site identification and confirmation surveys.
Site ID Date Time PRM Method
Eulachon
presence
Dominant
Behavior
Dominant
Condition
Egg
Release
1 May 29 14:00 17.5 dip net yes spawning spawning yes
2 May 31 15:00 25.5 dip net yes spawning spawning no
3 June 1 10:30 13.6 dip net yes spawning spawning no
4 June 1 14:08 25.3 dip net yes spawning spawning yes
5 June 2 12:55 25.6 dip net yes spawning spawning yes
6 June 2 11:00 33.4 dip net yes milling spawning yes
7 June 2 15:17 29.6 dip net yes spawning spawning yes
8 June 3 12:35 11.3 dip net yes spawning spawning yes
9 June 3 14:29 18.2 dip net yes spawning spawning yes
10 June 3 15:17 22.6 dip net yes spawning spawning yes
11 June 4 12:00 17.9 dip net yes spawning spawning yes
12 June 5 11:20 19.5 dip net yes spawning spawning yes
13 June 5 12:20 20.4 dip net yes spawning spawning yes
14 June 5 13:00 21 dip net yes spawning spawning yes
15 June 5 13:50 22.3 dip net yes spawning spawning yes
16 June 6 12:25 34.7 dip net no - - -
17 June 6 12:54 39.4 dip net yes spawning spawning yes
18 June 6 16:30 28.8 dip net yes spawning spawning yes
19 June 7 10:15 10.5 dip net yes spawning spawning yes
20 June 7 13:15 19.3 dip net yes milling spawning yes
21 June 7 14:21 25.2 dip net yes spawning spawning yes
22 June 8 12:48 27.7 dip net yes milling spawning yes
23 June 9 11:14 37.4 dip net yes milling spawning yes
24 June 9 12:53 43.1 dip net yes passing by spawning yes
25 June 9 13:40 44.3 dip net yes spawning spawning yes
26 June 10 12:37 50.3 dip net yes milling spawning yes
27 June 10 13:22 46.6 dip net yes spawning spawning yes
28 June 10 14:18 45.8 dip net yes milling spawning yes
29 June 11 10:49 38.5 dip net no - - -
30 June 12 14:04 52.5 dip net no - - -
31 June 13 12:34 30.8 dip net yes spawning spawning yes
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix A – Page 4 June 2014
Appendix Table A-4. Location, mesohabitat type, and substrate description at 28 spawning sites and three additional sites surveyed in 2013.
Substrate Classification
Site
ID Date Project
River Mile Mesohabitat Acoustic Description Visual Survey
1 May 29 17.5 run sand 100 % sand/silt
2 May 31 25.5 run sand 100 % sand/silt
3 June 1 13.6 run sand/silt 100 % sand/silt
4 June 1 25.3 shallow riffle sand 100 % sand/silt
5 June 2 25.6 run sand 100 % sand/silt
6 June 2 33.4 run gravel bar, finer sediment over gravel 25% sand/silt, 75% mixed gravel
7 June 2 29.6 run gravel and sand 100 % sand/silt
8 June 3 11.3 run sand 100 % sand/silt
9 June 3 18.2 run no side scan sample 100 % sand/silt
10 June 3 22.6 run gravel and sand 25% sand/silt, 75% mixed gravel
11 June 4 17.9 run no side scan sample 100 % sand/silt
12 June 5 19.5 run sand 100 % sand/silt
13 June 5 20.4 run sand 100 % sand/silt
14 June 5 21 shallow riffle sand 100 % sand/silt
15 June 5 22.3 shallow riffle sand 50% sand/silt, 50% mixed gravel
16 June 6 34.7 -- no side scan sample 100 % sand/silt
17 June 6 39.4 run no side scan sample 50% sand/silt, 50% mixed gravel
18 June 6 28.8 shallow riffle sand bank 100 % sand/silt
19 June 7 10.5 shallow riffle sand 100 % sand/silt
20 June 7 19.3 run sandbar 100 % sand/silt
21 June 7 25.2 run peat over clay base 100 % silt/clay and peat
22 June 8 27.7 run gravel bar 20% sand/silt, 80% mixed gravel
23 June 9 37.4 run no side scan sample 100 % sand/silt
24 June 9 43.1 run -- 100 % sand/silt
25 June 9 44.3 shallow riffle gravel 25% sand/silt, 75% mixed gravel
26 June 10 50.3 run no side scan sample 100 % sand/silt
27 June 10 46.6 shallow riffle gravel 20% sand/silt, 80% mixed gravel
28 June 10 45.8 run sand 100 % sand/silt
29 June 11 38.5 -- no side scan sample 100 % sand/silt
30 June 12 52.5 -- no side scan sample 30% sand/silt, 70% mixed gravel
31 June 13 30.8
run
no side scan sample 100 % sand/silt
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 June 2014
PART A - APPENDIX B: SIDE SCAN SONAR IMAGES
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix B – Page 1 June 2014
Appendix Figure B-1. Sand waves visible at mobile acoustic site 2 (Project River Mile 25.5) using side scan sonar in
2013.
Appendix Figure B-2. Side scan sonar showing the gravel bar at mobile acoustic site 6 (Project River Mile 33.4) in 2013.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix B – Page 2 June 2014
Appendix Figure B-3. Side scan sonar imagery of substrate at mobile acoustic site 10 (Project River Mile 22.6) in 2013
showing mixed gravel and sand/silt substrate.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 June 2014
PART A - APPENDIX C: SIDE SCAN SONAR IMAGES COMPARED TO
PHOTOGRAPHS
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 1 June 2014
Appendix Figure C-1. Side scan image and photograph of sand bar, weir and fixed transducer at Site 1 on May 30. Weir and fixed transducer mount
visible as bright reflections.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 2 June 2014
Appendix Figure C-2. Side scan image and photograph of submerged sand bar and the fixed transducer mount at Site 1. Large number of eulachon
present on June 8.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 3 June 2014
Appendix Figure C-3. Side scan image and photograph at shoreline of sand bar with eulachon spawning activity at Site 4. “Striations” appear to be
related to the presence of a large number of eulachon on June 1.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 4 June 2014
Appendix Figure C-4. Side scan image and photograph of cut bank along the shoreline at Site 5 on June 2. Side scan image suggests gravel base
under sand.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 5 June 2014
Appendix Figure C-5. Side scan image and photograph of the shoreline at Site 6 showing mixed gravel and sand on June 8.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 6 June 2014
Appendix Figure C-6. Side scan image and photograph of site showing sand/silt low cut bank under alders, with some gravel along the shore at Site 7
on June 2.
Appendix Figure C-7. Side scan image and photograph of sand stepped low cut bank at Site 8 on June 3.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 7 June 2014
Appendix Figure C-8. Side scan image and photograph of gravel and sand along the shoreline at Site 10 on June 3.
Appendix Figure C-9. Side scan image and photograph showing sand and high cut bank along the shoreline at Site 12 on June 5.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 8 June 2014
Appendix Figure C-10. Side scan image and photograph of shoreline at Site 13 showing sand and high cut bank on June 5.
Appendix Figure C-11. Side scan image and photograph of sand, some gravel, and stepped cut bank at Site 14 on June 5.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 9 June 2014
Appendix Figure C-12. Side scan image and photograph of sand stepped cut bank at Site 15 on June 5.
Appendix Figure C-13. Side scan image and photograph along shore showing sand bank, possibly with harder substrate at its base at Site 18 on
June 6.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 10 June 2014
Appendix Figure C-14. Side scan image and photograph showing sand and a low cut bank at Site 19 on June 7. Eulachon reflections and shadows are visible in the side scan image.
Appendix Figure C-15. Side scan image and photograph of steep bluff and peat over compacted clay base with possibly harder substrate below at Site 21 on June 7.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 11 June 2014
Appendix Figure C-16. Side scan image and photograph of gravel bar at Site 22 on June 8.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 12 June 2014
Appendix Figure C-17. Side scan image and photograph of gravel at base of high bluff at Site 27 on June 10.
INITIAL STUDY REPORT EULACHON RUN TIMING, DISTRIBUTION,
AND SPAWNING IN THE SUSITNA RIVER (9.16)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Appendix C – Page 13 June 2014
Appendix Figure C-18. Side scan image and photograph of sand cut bank at Site 28 on June 10.