Temporal and Spatial Distributions of Kenai River and Susitna River Sockeye Salmon and Coho Salmon in Upper Cook Inlet: Implications for Management

Fishery Data Series No. 17-02

by T. Mark Willette and Aaron Dupuis

February 2017 Alaska Department of Fish and Game Divisions of Sport Fish and Commercial Fisheries

1 Symbols and Abbreviations The following symbols and abbreviations, and others approved for the Système International d'Unités (SI), are used without definition in the following reports by the Divisions of Sport Fish and of Commercial Fisheries: Fishery Manuscripts, Fishery Data Series Reports, Fishery Management Reports, and Special Publications. All others, including deviations from definitions listed below, are noted in the text at first mention, as well as in the titles or footnotes of tables, and in figure or figure captions. Weights and measures (metric) General Mathematics, statistics centimeter cm Alaska Administrative all standard mathematical deciliter dL Code AAC signs, symbols and gram g all commonly accepted abbreviations hectare ha abbreviations e.g., Mr., Mrs., alternate hypothesis HA kilogram kg AM, PM, etc. base of natural logarithm e kilometer km all commonly accepted catch per unit effort CPUE liter L professional titles e.g., Dr., Ph.D., coefficient of variation CV meter m R.N., etc. common test statistics (F, t, χ2, etc.) milliliter mL at @ confidence interval CI millimeter mm compass directions: correlation coefficient east E (multiple) R Weights and measures (English) north N correlation coefficient cubic feet per second ft3/s south S (simple) r foot ft west W covariance cov gallon gal copyright  degree (angular ) ° inch in corporate suffixes: degrees of freedom df mile mi Company Co. expected value E nautical mile nmi Corporation Corp. greater than > ounce oz Incorporated Inc. greater than or equal to ≥ pound lb Limited Ltd. harvest per unit effort HPUE quart qt District of Columbia D.C. less than < yard yd et alii (and others) et al. less than or equal to ≤ et cetera (and so forth) etc. logarithm (natural) ln Time and temperature exempli gratia logarithm (base 10) log day d (for example) e.g. logarithm (specify base) log2, etc. degrees Celsius °C Federal Information minute (angular) ' degrees Fahrenheit °F Code FIC not significant NS degrees kelvin K id est (that is) i.e. null hypothesis HO hour h latitude or longitude lat or long percent % minute min monetary symbols probability P second s (U.S.) $, ¢ probability of a type I error months (tables and (rejection of the null Physics and chemistry figures): first three hypothesis when true) α all atomic symbols letters Jan,...,Dec probability of a type II error alternating current AC registered trademark  (acceptance of the null ampere A trademark  hypothesis when false) β calorie cal United States second (angular) " direct current DC (adjective) U.S. standard deviation SD hertz Hz United States of standard error SE horsepower hp America (noun) USA variance hydrogen ion activity pH U.S.C. United States population Var (negative log of) Code sample var parts per million ppm U.S. state use two-letter parts per thousand ppt, abbreviations ‰ (e.g., AK, WA) volts V watts W

FISHERIES DATA SERIES NO. 17-02

TEMPORAL AND SPATIAL DISTRIBUTIONS OF KENAI RIVER AND SUSITNA RIVER SOCKEYE SALMON AND COHO SALMON IN UPPER COOK INLET: IMPLICATIONS FOR MANAGEMENT

by T. Mark Willette and Aaron Dupuis Alaska Department of Fish and Game, Division of Commercial Fisheries, Soldotna

Alaska Department of Fish and Game Division of Sport Fish, Research and Technical Services 333 Raspberry Road, Anchorage, Alaska, 99518-1565 February 2017

ADF&G Fishery Data Series was established in 1987 for the publication of Division of Sport Fish technically oriented results for a single project or group of closely related projects, and in 2004 became a joint divisional series with the Division of Commercial Fisheries. Fishery Data Series reports are intended for fishery and other technical professionals and are available through the Alaska State Library and on the Internet: http://www.adfg.alaska.gov/sf/publications/ This publication has undergone editorial and peer review.

T. Mark Willette and A. Dupuis Alaska Department of Fish and Game, Division of Commercial Fisheries, 43961 Kalifornsky Beach Road, Suite B, Soldotna, Alaska 99669

This document should be cited as follows: Willette, T. M., and A. Dupuis. 2017. Temporal and spatial distributions of Kenai River and Susitna River sockeye salmon and coho salmon in Upper Cook Inlet: implications for management. Alaska Department of Fish and Game, Fishery Data Series No. 17-02, Anchorage.

The Alaska Department of Fish and Game (ADF&G) administers all programs and activities free from discrimination based on race, color, national origin, age, sex, religion, marital status, pregnancy, parenthood, or disability. The department administers all programs and activities in compliance with Title VI of the Civil Rights Act of 1964, Section 504 of the Rehabilitation Act of 1973, Title II of the Americans with Disabilities Act (ADA) of 1990, the Age Discrimination Act of 1975, and Title IX of the Education Amendments of 1972. If you believe you have been discriminated against in any program, activity, or facility please write: ADF&G ADA Coordinator, P.O. Box 115526, Juneau, AK 99811-5526 U.S. Fish and Wildlife Service, 4401 N. Fairfax Drive, MS 2042, Arlington, VA 22203 Office of Equal Opportunity, U.S. Department of the Interior, 1849 C Street NW MS 5230, Washington DC 20240 The department’s ADA Coordinator can be reached via phone at the following numbers: (VOICE) 907-465-6077, (Statewide Telecommunication Device for the Deaf) 1-800-478-3648, (Juneau TDD) 907-465-3646, or (FAX) 907-465-6078 For information on alternative formats and questions on this publication, please contact: ADF&G, Division of Sport Fish, Research and Technical Services, 333 Raspberry Rd, Anchorage AK 99518 (907) 267-2375

TABLE OF CONTENTS Page LIST OF FIGURES ...... i ABSTRACT ...... 1 INTRODUCTION ...... 1 OBJECTIVES ...... 2 METHODS ...... 3 RESULTS ...... 6 Southern OTF ...... 6 Across Time ...... 6 Across Stations ...... 6 Northern OTF ...... 6 Across Time ...... 7 Across Stations ...... 7 DISCUSSION ...... 7 ACKNOWLEDGEMENTS ...... 8 REFERENCES CITED ...... 9 FIGURES ...... 11

LIST OF FIGURES Page 1. Fishery districts and subdistricts in the Upper Cook Inlet management area...... 12 2. Boundaries of the drift gillnet fishery management areas 1 and 2...... 13 3. Boundaries of the drift gillnet fishery expanded Kenai and Kasilof sections...... 14 4. Bathymetry and major tide rips in Upper Cook Inlet and locations of stations along the southern offshore test fishery transect...... 15 5. Locations of stations fished by the northern offshore test fishery vessel and locations of the boundaries of the expanded Kenai and Kasilof sections and drift gillnet area 1...... 16 6. Mean Susitna River sockeye salmon catch per unit effort (CPUEst) by date stratum along the southern OTF transect, 2006–2012 and 2014...... 17 7. Mean daily catch per unit effort (CPUEst,i) for Kenai and Susitna river sockeye salmon and mean daily coho salmon CPUEi pooled across all years (2006–2012 and 2014) along the southern OTF transect ...... 18 8. Mean daily run proportions (PCPUEst,i) for Kenai and Susitna river sockeye salmon and coho salmon (PCPUEi) pooled across all years (2006–2012 and 2014) along the southern OTF transect...... 19 9. Mean cumulative proportion of total PCPUEst,i for Kenai and Susitna river sockeye salmon and coho salmon PCPUEi pooled across all years (2006–2012 and 2014) along the southern OTF transect...... 20 10. Mean Kenai River sockeye salmon catch per unit effort (CPUEst) by date stratum along the southern OTF transect, 2006–2012 and 2014...... 21 11. Mean coho salmon catch per unit effort by date stratum along the southern OTF transect, 2006–2012 and 2014...... 22 12. Ratios of mean Kenai to Susitna river sockeye salmon CPUEst by date stratum along the southern OTF transect, 2006–2012 and 2014...... 23 13. Ratios of mean Kenai River sockeye salmon CPUEst to mean coho salmon CPUEi by date stratum along the southern OTF transect, 2006–2012 and 2014...... 24 14. Total Susitna River sockeye salmon catch per unit effort (CPUEst) by station along the southern OTF transect, 2009–2012 and 2014...... 25

LIST OF FIGURES (Continued) Page 15. Mean total Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst,s) and mean total coho salmon CPUE pooled across all years by station along the southern OTF transect ...... 26 16. Total Kenai River sockeye salmon catch per unit effort (CPUEst,s) by station along the southern OTF transect, 2009–2012 and 2014...... 27 17. Total coho salmon catch per unit effort by station along the southern OTF transect, 2009-2012 and 2014...... 28 18. Ratios of total Kenai to Susitna river sockeye salmon catch per unit effort (CPUEst,s) by station along the southern OTF transect, 2006–2012 and 2014...... 29 19. Ratios of total Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE by station along the southern OTF transect, 2006–2012 and 2014...... 30 20. Mean Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst) and mean coho salmon CPUE by date stratum along the northern OTF transect, 2012–2014...... 31 21. Mean daily catch per unit effort (CPUEst,i) for Kenai and Susitna river sockeye salmon and mean daily coho salmon CPUEi pooled across all years (2012–2014) along the northern OTF transect...... 32 22. Mean daily run proportions (PCPUEst,i) for Kenai and Susitna river sockeye salmon and mean daily coho salmon run proportions (PCPUEi) pooled across all years along the northern OTF transect...... 33 23. Mean cumulative proportion of total PCPUEst,i for Kenai and Susitna river sockeye salmon and coho salmon (PCPUEi) pooled across all years (2012–2014) along the northern OTF transect...... 34 24. Ratios of mean Kenai to Susitna river sockeye salmon catch per unit effort (CPUEst) by date stratum, and ratios of mean Kenai River sockeye salmon CPUEst to mean coho salmon CPUEi by date stratum along the northern OTF transect 2012–2014...... 35 25. Total Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst,s) and total coho salmon CPUE by station along the northern OTF transect, 2012–2014...... 36 26. Mean total Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst,s) and mean total coho salmon CPUE pooled across all years (2012–2014) by station along the northern OTF transect ...... 37 27. Ratios of total Kenai to Susitna river sockeye salmon catch per unit effort (CPUEst,s) and ratios of total Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE by station along the northern OTF transect, 2012–2014...... 38

ABSTRACT This study investigated the temporal and spatial distributions of Kenai and Susitna river sockeye salmon (Oncorhynchus nerka) and coho salmon (O. kisutch; all stocks combined) in Upper Cook Inlet using southern offshore test fishery (OTF) catch per unit effort (CPUE) and sockeye salmon genetic data from 2006–2012 and 2014 and northern OTF CPUE and genetic data from 2012–2014. Spatial and temporal opportunities to harvest Kenai River sockeye salmon while minimizing harvests of Susitna River sockeye salmon or coho salmon were investigated using CPUE ratios for these stocks. Mean daily ratios of Kenai to Susitna river sockeye salmon CPUEs generally exceeded 10:1 after about July 20. Mean daily ratios of Kenai River sockeye salmon to coho salmon CPUEs generally exceeded 10:1 prior to July 11 along the southern transect and prior to July 18 along the northern transect. These temporal CPUE patterns indicate that in general Kenai River sockeye salmon may be harvested at a higher rate compared to Susitna River sockeye salmon after July 20, but harvest rates on coho salmon will also be higher during this period. Mean CPUE ratios of Kenai to Susitna river sockeye salmon exceeded 10:1 on the eastern end of the northern transect. Mean CPUE ratios of Kenai River sockeye salmon to coho salmon exceeded 10:1 on the eastern end of both transects with the pattern more pronounced along the northern transect. These spatial CPUE patterns indicate that in general Kenai River sockeye salmon may be harvested at a higher rate compared to Susitna River sockeye salmon and coho salmon along the eastern side of Cook Inlet, but harvest rates on Kenai River sockeye salmon would be highest near the center of the inlet. Additional years of sampling will be needed to better estimate stock-specific spatial and temporal distributions and their variability. Key words: Sockeye salmon, Oncorhynchus nerka, coho salmon, Oncorhynchus kisutch, Kenai River, Susitna River, Upper Cook Inlet, offshore test fishery (OTF), catch per unit effort (CPUE), genetic, mixed stock analysis INTRODUCTION Salmon are commercially harvested in Upper Cook Inlet (UCI) using drift and set gillnets, and these fisheries are managed to achieve salmon escapement goals in several streams flowing into the inlet. Drift gillnet fisheries are conducted only in the Central District; whereas set gillnet fisheries are conducted in both the Central and Northern districts on both the eastern and western shores (Figure 1). During each season, regularly scheduled drift and set gillnet fishery openings have occurred for 12 hours on Mondays and Thursdays beginning at 7:00 a.m. Additional fishing time has been allowed via emergency orders depending on catches, escapements, and the projected run size of sockeye salmon Oncorhynchus nerka (Shields and Dupuis 2015). To achieve escapement goals, drift and set gillnet fisheries have sometimes been restricted to smaller portions of the district to reduce the harvest of specific salmon stocks. These area restrictions have varied throughout each season and across years. Drift gillnet fisheries were sometimes restricted to areas south of the northern or southern tip of Kalgin Island (Figure 2), or to the reduced Kenai or Kasilof corridors along the eastside beaches usually to reduce harvests of Susitna River sockeye salmon and Northern District coho salmon O. kisutch. In 2008, the Alaska Board of Fisheries (BOF) declared Susitna River sockeye salmon as a stock of yield concern. In 2011, the BOF created the Expanded Kenai and Kasilof sections (Figure 3) to provide for harvest of Kenai and Kasilof river sockeye salmon while minimizing harvests of Susitna River sockeye salmon and Northern District coho salmon. Descriptions of the management plans governing these fisheries and details of these restrictions for specific years can be found in the UCI Annual Management Reports (Shields and Dupuis 2012, 2013a, 2013b, 2015). Since 1979, the Alaska Department of Fish and Game (ADF&G) has conducted an offshore test fishery (OTF) project near the southern boundary of the UCI salmon management area (Figure 4). The objective of this project has been to estimate the total run of sockeye salmon returning to UCI before these fish reach commercial harvest areas. Annually since 1992, 6 stations have been

fished each day in July along the southern OTF transect running west from Anchor Point. These 6 stations were located near the center of the inlet where the majority of salmon typically migrate as they follow tide rips (Figure 4). Beginning in 2006, tissue samples were collected from sockeye salmon harvested in the southern OTF to estimate stock composition using genetics. In 2012, a northern OTF project was initiated to investigate the spatial and temporal distributions of sockeye and coho salmon in the Central District drift fishery area. Genetic tissue samples were collected from sockeye (2012) and coho (2013–2014) salmon harvested in this test fishery. In 2012–2013, 7 stations were fished along a transect extending across the northern tip of Kalgin Island (Figure 5). Stations were generally located near tide rips which tend to occur where the bottom slope is relatively steep (Burbank 1977), but stations were also located inside and outside of the Expanded Kenai and Kasilof sections. In 2014, the two stations (6 and 7) located west of Kalgin Island and station 1 located on the east side were dropped due to low catches. Instead two transects were fished, one extending across the northern tip of Kalgin Island (same stations as in 2012–2013) and a second extending across the southern tip of Kalgin Island (Figure 5). This transect design was used to investigate whether the spatial and temporal catch per unit effort (CPUE) patterns observed along the northern Kalgin Island transect were consistent across a broader area of the Central District. As in 2012, stations were generally located near tide rips, and stations along the southern and northern Kalgin Island transects were paired to approximately follow the same bathymetric contour—i.e., stations 5 and 8, 4 and 9, 3 and 10, and 2 and 11 (Figure 5). Stations were also located inside and outside of the Expanded Kenai and Kasilof sections, and the southern Kalgin Island transect was positioned just inside the northern boundary of Drift gillnet Area 1. In this report, we investigate the temporal and spatial distributions of Kenai and Susitna river sockeye salmon and coho salmon (all Cook Inlet stocks combined) in UCI to investigate spatial and temporal opportunities to harvest Kenai River sockeye salmon while minimizing harvests of Susitna River sockeye salmon or coho salmon. We used (1) southern OTF CPUE and sockeye salmon genetic data from 2006–2012, and 2014, and (2) northern OTF CPUE and sockeye salmon genetic data from 2012–2014 (Shields and Willette 2008, 2009a, 2009b, 2010, 2011; Shields et al. 2013; Dupuis and Willette 2014; Dupuis et al. 2015, 2016). Southern OTF data from 2013 were not included in the analysis due to the large number of stations that were not fished. Although coho salmon genetic data were not available for this analysis, Willette et al. (2003) found that 94% of coho salmon radio tagged (n = 729) along the southern OTF transect were later relocated in Northern District streams primarily the Susitna and Little Susitna rivers (56%). We also calculated the ratio of Kenai to Susitna river sockeye salmon CPUEs and the ratio of Kenai River sockeye salmon to coho salmon CPUEs to identify opportunities to harvest Kenai River sockeye salmon while minimizing harvests of the other stocks. OBJECTIVES The objectives of this study were to: 1. Evaluate the temporal and spatial distributions of Kenai and Susitna river sockeye salmon and UCI coho salmon CPUEs along the southern (2006–2012 and 2014) and northern (2012–2014) OTF transects, 2. Evaluate the temporal and spatial distributions of the ratio of Kenai to Susitna river sockeye salmon CPUEs along the southern (2006–2012 and 2014) and northern (2012–2014) OTF transects,

3. Evaluate the temporal and spatial distributions of the ratio of Kenai River sockeye salmon to UCI coho salmon CPUEs along the southern (2006–2012, 2014) and northern (2012–2014) OTF transects, 4. Evaluate the mean daily CPUEs pooled across all years for Kenai and Susitna river sockeye salmon and UCI coho salmon along the southern (2006–2012 and 2014) and northern (2012–2014) OTF transects, and 5. Evaluate the mean total CPUEs pooled across all years for Kenai and Susitna river sockeye salmon and UCI coho salmon by station along the southern (2006–2012 and 2014) and northern (2012–2014) OTF transects. METHODS Dupuis et al. (2015) provides a detailed description of the methods used in the UCI offshore test fishery project. Briefly, the number of fish captured at each station s on each day i was expressed as a CPUE statistic that was standardized to the number of fish caught in 100 fathoms of gear in one hour of fishing time: 100 fm × 60 min × number of fish CPUE = . (1) s,i fm of gear × MFT Mean fishing time (MFT) was: (B − A) + (D − C) MFT = (C − B) + , (2) 2 where: A = time net deployment started, B = time net fully deployed, C = time net retrieval started, and D = time net fully retrieved. Once deployed at a station, drift gillnets were fished 30 minutes before retrieval was started. However, the net was capable of capturing fish prior to being fully deployed and when it was being retrieved. MFT was therefore adjusted by summing the total time it took to set and retrieve the net, then dividing this time in half, and adding it to the time when the entire net was deployed and fished (equation 2).

Daily CPUEs,i data were summed for all m stations as follows:

m CPUEi = ∑CPUEs,i . (3) s=1 The left axillary process was removed from sockeye salmon captured at each station on the southern (station n ≤ 50) and northern (station n ≤ 75) OTF transects for later genetic analysis (Habicht et al. 2007). Barclay et al. (2010a) describe the methods used for genetic sample quality control and data retrieval, and Barclay and Habicht (2012) describe the methods used for genetic mixed stock analysis. Genetic sockeye salmon stock proportions were estimated for temporal strata of various lengths each year to achieve a minimum of approximately 400 tissue samples.

Mean stock-specific (st) sockeye salmon catch per unit effort statistics (CPUEst) were estimated for each temporal stratum in each year for both the southern and northern OTF transects using a simulation model with 10,000 iterations to estimate the mean and variance of CPUEst for each stratum, i.e.

(4) CPUEst = [CPUEsi ⋅ (sdCstr ⋅ε )]⋅[Pstr + (sd Pstr ⋅ε )]

where CPUE si was the stratum mean sockeye salmon CPUEi (Shields and Willette 2008, 2009a, 2009b, 2010, 2011; Shields et al. 2013; Dupuis and Willette 2014; Dupuis et al. 2015, 2016),

sdCstr was the standard deviation of CPUE si , Pstr was the genetic stock proportion in stratum str (Barclay et al. 2010a, 2010b, 2013, 2014, Dupuis et al. 2016), sdPstr was the standard deviation of Pstr and ε were random numbers with normal distributions, a mean of zero and a variance of 1 (RANNOR Function, SAS Institute, Cary, NC). The 90% confidence intervals for the mean CPUEst were approximated using the 5th and 95th percentiles of the distribution of CPUEst estimates. CPUEst were natural logarithm transformed before calculating means and percentiles to normalize their distribution (Quinn and Deriso 1999). Mean CPUEst for Susitna River sockeye salmon were estimated by summing Pstr and their variances for the Judd, Chelatna, and Larson lake (JCL) and other Susitna and Yentna River (SusYen) reporting groups. Mean coho salmon catch per effort statistics and their 90% confidence intervals were estimated for each stratum after natural logarithm transformation as described in Zar (1984). Linear interpolation was first applied to estimate missing CPUEs,i data within each stratum. Stratum mean CPUEi was used in this analysis rather than stratum ∑CPUEi to correct for variable stratum lengths. The ratio of mean Kenai to Susitna river sockeye salmon CPUEst and the ratio of mean Kenai River sockeye salmon CPUEst to mean coho salmon CPUE were calculated for each stratum to investigate temporal opportunities to harvest Kenai River sockeye salmon while minimizing harvests of Susitna River sockeye salmon or coho salmon. Stock-specific mean run timings (all years combined) were next estimated for both the southern and northern OTF transects using a simulation model with 10,000 iterations to estimate the mean and variance of CPUEst for each day in July after pooling data across all years. Daily stock- specific sockeye salmon catch per unit effort statistics (CPUEst,i) were estimated within each stratum:

CPUEst,i = CPUEi ⋅[Pstr + (sd Pstr ⋅ε )], (5)

where CPUEi was the total daily sockeye salmon CPUE for each of the days within temporal stratum str. CPUEst,i for Susitna River sockeye salmon were estimated by summing Pstr and their variances for the JCL and SusYen reporting groups. The 90% confidence intervals for mean CPUEst,i were approximated using the 5th and 95th percentiles of the distribution of CPUEst,i estimates. CPUEst,i were natural logarithm transformed before calculating means and percentiles. The simulation model also calculated the ratio of Kenai to Susitna river sockeye salmon CPUEst,i and the ratio of Kenai River sockeye salmon CPUEst,i to coho salmon CPUEi in each iteration. Mean daily ratios were then calculated after pooling data across years, and the 90% confidence intervals for the mean ratios were approximated using the 5th and 95th percentiles of their distributions. Mean daily coho salmon CPUEi were estimated using the simulation model after pooling data across years, and the 90% confidence intervals for the mean CPUEi were approximated using the 5th and 95th percentiles of their distributions.

Since mean run timing estimated using CPUEst,i could be biased due to the relative magnitude of CPUEs among years, run timing was also estimated by calculating CPUEst,i for each year separately and then dividing by the total annual CPUEst,i, i.e.,

CPUE PCPUE = st,i , st,i 30 (6) ∑CPUEst,i i=1

where PCPUEst,i was the estimated mean daily run proportion for a given stock. The mean and variance of the simulated daily PCPUEst,i were then estimated as described above with all years pooled. The mean mid-point of the run for each stock was estimated from the cumulative mean PCPUEst,i. The same methods were used to estimate the mean run timing of coho salmon (PCPUEi).

Total stock-specific catch per unit effort statistics (CPUEst,s) for each station were used to describe spatial distributions of Kenai and Susitna river sockeye salmon in each year:

30 (7) CPUEst,s = ∑CPUEs,i ⋅ Ps , i=1

where Ps was the genetic stock proportion for each station. The 90% credibility intervals on CPUEst,s were estimated by multiplying the genetic stock proportion 90% credibility intervals by the CPUEst,s for each station. Spatial distributions of coho salmon in each year were also described using station total catch per unit effort statistics. Ratios of Kenai to Susitna river sockeye salmon CPUEst,s and Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE were also calculated by station in each year. Mean stock-specific distributions of Kenai and Susitna river sockeye salmon along the southern and northern OTF transects were also estimated using a simulation model with 10,000 iterations to estimate the mean and variance of CPUEst,s after pooling data across all years. Total stock-specific sockeye salmon catch per unit effort statistics (CPUEst,s) were estimated for each station:

30 (8) CPUEst,s = ∑CPUEs,i ⋅[Ps + (sd s ⋅ε )], i=1

where sds was the standard deviation of Ps. The 90% confidence intervals for mean CPUEst,s th th were approximated using the 5 and 95 percentiles of the distribution of CPUEst,s estimates. Only data from stations 1–5 sampled in 2012–2013, as well as data from comparable stations (i.e., stations 5 and 8, 4 and 9, 3 and 10, and 2 and 11) sampled along the upper and lower Kalgin Island transects in 2014 were included in this analysis (Figure 5). CPUEst,s were natural logarithm transformed before calculating means and percentiles. The simulation model also calculated the ratio of total Kenai to Susitna river sockeye salmon CPUEst,s and the ratio of total Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE in each iteration. Mean station ratios were then calculated after pooling data across years and the 90% confidence intervals for the mean ratios were approximated using the 5th and 95th percentiles of their distributions. Mean coho salmon CPUE were estimated after pooling data across years, and the 90% confidence intervals for the mean CPUE were approximated using the 5th and 95th percentiles of their distributions.

RESULTS SOUTHERN OTF Across Time

Mean Susitna River sockeye salmon CPUEst along the southern OTF transect peaked between July 5 and 18 in all years except in 2006 and 2012 when it peaked between July 17 and 23 (Figure 6). Mean daily Susitna River sockeye salmon CPUEst,i pooled across all years (Figure 7) and mean daily run proportions (PCPUEst,i) peaked between July 10 and 17 (Figure 8). The mean date of the Susitna River sockeye salmon run across the southern transect was July 14 (Figure 9). Mean Kenai River sockeye salmon CPUEst peaked between July 8 and 18 in all years except 2006 and 2012 (Figure 10) when CPUEs peaked between July 24–31 and July 17–19, respectively. Mean daily Kenai River sockeye salmon CPUEst,i pooled across all years (Figure 7) and mean daily run proportions (PCPUEst,i) peaked between July 13 and 17 (Figure 8). The mean date of the Kenai River sockeye salmon run was July 17 (Figure 9). Mean coho salmon CPUEi peaked after July 17 in all years except 2008 and 2010, when it peaked the week prior (Figure 11). Mean daily coho salmon CPUEi pooled across all years (Figure 7) and mean daily run proportions (PCPUEi) increased steadily throughout July (Figure 8). The mean date of the coho salmon run was July 21 (Figure 9).

The ratios of mean Kenai to Susitna river sockeye salmon CPUEst generally increased after July 10 except in 2014 (Figure 12), and the mean daily ratios pooled across all years increased steadily after July 10 (Figure 7). The ratios of mean Kenai River sockeye salmon CPUEst to mean coho salmon CPUEi generally decreased throughout July except in 2006 (Figure 13), and the mean daily ratios pooled across all years also decreased throughout July (Figure 7). Across Stations

Total Susitna River sockeye salmon CPUEst,s were generally highest at stations 6 or 6.5 in 2009-2010 and 2012 (Figure 14), and mean total CPUEst,s pooled across all years were also highest at stations 6 and 6.5 (Figure 15). Total Kenai River sockeye salmon CPUEst,s were generally highest at stations 6 or 6.5 in 2010–2014 (Figure 16), and mean total CPUEst,s pooled across all years were also highest at stations 6 and 6.5 (Figure 15). Total coho salmon CPUE were highest at stations 5, 6 or 6.5 in all years except 2011, when the highest CPUE was at station 7 (Figure 17), and mean total coho salmon CPUE pooled across all years were highest at station 6.5 (Figure 15).

Ratios of total Kenai to Susitna river sockeye salmon CPUEst,s exhibited no consistent pattern along the southern OTF transect (Figures 15 and 18). Ratios of total Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE tended to be higher along the eastern end of the transect (Figure 19), and the mean ratios pooled across all years were highest at stations 4 and 5 (Figure 15). NORTHERN OTF Although the northern OTF project sampled two transects in 2014 (Figure 5), it will be referred to as simply the northern OTF transect, because CPUE patterns were similar between the upper and lower Kalgin Island transects.

Across Time

Stratum mean Susitna River sockeye salmon CPUEst peaked between July 14 and 20 along the northern OTF transect in 2012–2014 (Figure 20). Mean daily Susitna River sockeye salmon CPUEst,i pooled across all years (Figure 21) and mean daily run proportions (PCPUEst,i) peaked on July 14 (Figure 22). The mean date of the Susitna River sockeye salmon run across the northern transect was July 15 (Figure 23). Stratum mean Kenai River sockeye salmon CPUEst peaked between July 14 and 24 in 2012–2014 (Figure 20). Mean daily Kenai River sockeye salmon CPUEst,i pooled across all years (Figure 21) and mean daily run proportions (PCPUEst,i) peaked on July 14 (Figure 22). The mean date of the Kenai River sockeye salmon run was July 16 (Figure 23). Stratum mean coho salmon CPUEi peaked between July 26–30 in 2012, July 14–15 in 2013 and July 21–24 in 2014 (Figure 20). Mean daily coho salmon CPUEi pooled across all years (Figure 21) and mean daily run proportions (PCPUEi) generally increased after July 12 (Figure 22). The mean date of the coho salmon run was July 23 (Figure 23).

The ratios of stratum mean Kenai to Susitna river sockeye salmon CPUEst generally increased throughout July (Figure 24), and the mean daily ratios pooled across all years also increased after July 15 (Figure 21). The ratios of stratum mean Kenai River sockeye salmon CPUEst to mean coho salmon CPUEi decreased throughout July in 2012 and 2014 but not in 2013 (Figure 24), and the mean daily ratios pooled across all years peaked July 13–14 (Figure 21). Across Stations

Total Susitna River sockeye salmon CPUEst,s were highest at stations 4 in 2012, stations 3–5 in 2013 and stations 3 and 10 and 4 and 9 in 2014 (Figure 25). Mean total Susitna River sockeye salmon CPUEst,s pooled across all years were highest at stations 3–4 (Figure 26). Total Kenai River sockeye salmon CPUEst,s were highest at stations 3–4 in 2012, station 3 in 2013 and stations 3 and 10 and 4 and 9 in 2014 (Figure 25). Mean Kenai River sockeye salmon CPUEst,s pooled across all years were also highest at stations 3–4 (Figure 26). Total coho salmon CPUE were highest at stations 3–4 in 2012, station 5 in 2013 and stations 5 and 8 in 2014 (Figure 25). Mean total coho salmon CPUE pooled across all years were highest at stations 4–5 (Figure 26).

The ratios of total Kenai to Susitna river sockeye salmon CPUEst,s were generally greater on the eastern side of the transect in all years (Figure 27), and the mean ratios pooled across all years were highest at stations 1–2 (Figure 26). The ratios of Kenai River sockeye salmon CPUEst,s to coho salmon CPUE were also highest on the eastern end of the transect in all years (Figure 27), and the mean ratios pooled across all years were highest at stations 1–2 (Figure 26). DISCUSSION Although temporal and spatial patterns of CPUE varied considerably among years and variances on mean CPUEs were high, some patterns were consistent between the southern and northern OTF transects. Mean daily CPUEst,i and mean daily run proportions pooled across all years exhibited very similar temporal patterns between the southern and northern OTF transects. Along both transects mean daily Susitna River sockeye salmon CPUEst,i peaked July 10–17, but the run was more compressed along the northern transect (Figures 7 and 21). Mean daily Kenai River sockeye salmon CPUEst,i exhibited a similar pattern with peak CPUEs occurring July 13-17 along both transects, and the run was more compressed along the northern transect. The mean dates of the Susitna and Kenai river sockeye salmon runs also differed by only one day between the two transects (Figures 9 and 23) despite the fact that samples were collected

along the southern transect in 6 years (2006–2011) when the northern transect was not sampled. Mean daily coho salmon CPUEi also exhibited similar temporal patterns between the two transects with an increase in mean CPUEi after July 12 (Figures 7 and 21), and the mean date of the run differed by only 2 days between the two transects (Figures 9 and 23).

Temporal patterns of mean daily ratios of Kenai to Susitna river sockeye salmon CPUEst,i were similar between the two transects with ratios generally exceeding 10:1 after about July 20 (Figures 7 and 21). Higher Kenai to Susitna river CPUEst,i ratios after July 20 were due to a more prolonged Kenai River run compared to Susitna River. Temporal patterns of mean daily ratios of Kenai River sockeye salmon CPUEst,i to coho salmon CPUEi differed between the two transects with ratios generally exceeding 10:1 prior to July 11 along the southern transect and prior to July 18 along the northern transect (Figures 7 and 21), but CPUE ratios generally declined below 10:1 along both transects after July 20. These temporal CPUE patterns indicate that in general Kenai River sockeye salmon may be harvested at a higher rate compared to Susitna River sockeye salmon after July 20, but harvest rates on coho salmon will also be higher during this period. Comparisons of spatial patterns of CPUE between the two transects were less clear in part due to the relatively close spacing of stations along the southern transect. However, mean total Kenai and Susitna river sockeye salmon CPUEst,s were highest near the center of both transects, but mean total coho salmon CPUEs were highest near the center of the southern transect and on the western end of the northern transect (Figures 15 and 26).

Mean ratios of Kenai to Susitna river sockeye salmon CPUEst,s exhibited no clear spatial pattern along the southern transect, but the mean ratio exceeded 10:1 on the eastern end of the northern transect (Figures 15 and 26). Mean ratios of Kenai River sockeye salmon CPUEst,s to coho salmon CPUE exceeded 10:1 on the eastern end of both transects with the pattern more pronounced along the northern transect (Figures 15 and 26). Lower mean ratios of Kenai River sockeye salmon to coho salmon CPUEs along the western end of the northern transect were due to the more westward distribution of coho salmon along this transect. These spatial CPUE patterns indicate that in general Kenai River sockeye salmon may be harvested at a higher rate compared to Susitna River sockeye salmon and coho salmon along the eastern side of Cook Inlet, but harvest rates on Kenai River sockeye salmon would be highest near the center of the inlet. The temporal and spatial mean CPUE patterns described here would not be expected to be consistent from year to year due to changes in run timings and run-entry patterns of various salmon stocks. However, these results provide a preliminary description of the general spatial and temporal distributions of major sockeye and coho salmon stocks migrating through the Central District. Additional years of sampling will be needed to better estimate stock-specific spatial and temporal distributions and their variability. ACKNOWLEDGEMENTS The authors would like to thank Roland Maw, captain of the FV Americanus, and the test fish crewmembers for conducting safe and efficient maritime activities in 2006–2012. The authors would like to thank Travis Mercer (captain of the F/V Point Adams) and Richard Thompson (captain of the F/V Lady Alyce), and the test fishery crew members for conducting safe and efficient maritime activities in 2013. Finally, the authors would like to thank Robert Maw (captain of the F/V Ryan J), Greg Drais (captain of the F/V Lady Alyce), Roland Maw (captain of the F/V Americanus), and the test fishery crew members for conducting safe and efficient maritime activities in 2014.

REFERENCES CITED Barclay, A. W., and C. Habicht. 2012. Genetic baseline for Upper Cook Inlet sockeye salmon: 96 SNPs and 10,000 fish. Alaska Department of Fish and Game, Fishery Manuscript No. 12-06, Anchorage. Barclay, A. W., C. Habicht, W. D. Templin, H. A. Hoyt, T. Tobias, and T. M. Willette. 2010a. Genetic stock identification of Upper Cook Inlet sockeye salmon harvest, 2005–2008. Alaska Department of Fish and Game, Fishery Manuscript No. 10-01, Anchorage. Barclay, A. W., C. Habicht, T. Tobias, and T. M. Willette. 2010b. Genetic stock identification of Upper Cook Inlet sockeye salmon harvest, 2009. Alaska Department of Fish and Game, Fishery Data Series No. 10-93, Anchorage. Barclay, A. W., C. Habicht, T. Tobias, and T. M. Willette. 2013. Genetic stock identification of Upper Cook Inlet sockeye salmon harvest, 2010. Alaska Department of Fish and Game, Fishery Data Series No. 13-56, Anchorage. Barclay, A. W., C. Habicht, T. Tobias, E. L. Chenoweth and T. M. Willette. 2014. Genetic stock identification of Upper Cook Inlet sockeye salmon harvest, 2011. Alaska Department of Fish and Game, Fishery Data Series No. 14-43, Anchorage. Burbank, D. C. 1977. Circulation studies in Kachemak Bay and lower Cook Inlet, Environmental studies of Kachemak Bay and lower Cook Inlet. L.L. Trasky et al., editors. Marine/coastal habitat management report, Alaska Department of Fish and Game, Anchorage. Dupuis, A., and M. Willette. 2014. Migratory timing and abundance estimates of sockeye salmon into Upper Cook Inlet, Alaska, 2012. Alaska Department of Fish and Game, Fishery Data Series No. 14-25, Anchorage. Dupuis, A., M. Willette, and A. Barclay. 2015. Migratory timing and abundance estimates for sockeye salmon in Upper Cook Inlet, Alaska, 2013. Alaska Department of Fish and Game, Fishery Data Series No. 15-32, Anchorage. Dupuis, A., M. Willette, and A. Barclay. 2016. Migratory timing and abundance estimates for sockeye salmon in Upper Cook Inlet, Alaska, 2014. Alaska Department of Fish and Game, Fishery Data Series No. 16-43, Anchorage. Habicht, C., W. D. Templin, L. W. Seeb, L. F. Fair, T. M. Willette, S. W. Raborn, and T. L. Lingnau. 2007. Postseason stock composition analysis of Upper Cook Inlet sockeye salmon harvest, 2005–2007. Alaska Department of Fish and Game, Fishery Manuscript No. 07-07, Anchorage. Quinn, T. J., and R. B. Deriso. 1999. Quantitative Fish Dynamics. Oxford University Press, New York. Shields, P., and A. Dupuis. 2012. Upper Cook Inlet commercial fisheries annual management report, 2011. Alaska Department of Fish and Game, Fishery Management Report No. 12-25, Anchorage. Shields, P., and A. Dupuis. 2013a. Upper Cook Inlet commercial fisheries annual management report, 2012. Alaska Department of Fish and Game, Fishery Management Report No. 13-21, Anchorage. Shields, P., and A. Dupuis. 2013b. Upper Cook Inlet commercial fisheries annual management report, 2013. Alaska Department of Fish and Game, Fishery Management Report No. 13-49, Anchorage. Shields, P., and A. Dupuis. 2015. Upper Cook Inlet commercial fisheries annual management report, 2014. Alaska Department of Fish and Game, Fishery Management Report No. 15-20, Anchorage. Shields, P., and M. Willette. 2008. An estimate of the migratory timing and abundance of sockeye salmon into Upper Cook Inlet, Alaska, 2006. Alaska Department of Fish and Game, Fishery Data Series No. 08-53, Anchorage. Shields, P., and M. Willette. 2009a. Migratory timing and abundance estimates of sockeye salmon into Upper Cook Inlet, Alaska, 2007. Alaska Department of Fish and Game, Fishery Data Series No. 09-15, Anchorage. Shields, P., and M. Willette. 2009b. Migratory timing and abundance estimates of sockeye salmon into Upper Cook Inlet, Alaska, 2008. Alaska Department of Fish and Game, Fishery Data Series No. 09-59, Anchorage.

REFERENCES CITED (Continued) Shields, P., and M. Willette. 2010. Migratory timing and abundance estimates of sockeye salmon into Upper Cook Inlet, Alaska, 2009. Alaska Department of Fish and Game, Fishery Data Series No. 10-56, Anchorage. Shields, P., and M. Willette. 2011. Migratory timing and abundance estimates of sockeye salmon into Upper Cook Inlet, Alaska, 2010. Alaska Department of Fish and Game, Fishery Data Series No. 11-74, Anchorage. Shields, P., M. Willette, and A. Dupuis. 2013. Migratory timing and abundance estimates of sockeye salmon into Upper Cook Inlet, Alaska, 2011. Alaska Department of Fish and Game, Fishery Data Series No. 13-35, Anchorage. Willette, T. M., R. DeCino and N. Gove. 2003. Mark-recapture population estimates of coho, pink and chum salmon runs to Upper Cook Inlet, 2002. Alaska Department of Fish and Game, Regional Information Report No. 2A03–20. Zar, J. H. 1984. Biostatistical Analysis. 2nd edition. Prentice-Hall, Inc., Englewood Cliffs, NJ.

FIGURES

NORTHERN DISTRICT GENERAL 247-10 Trading Bay

247-20 Tyonek 50 -

247-30 Beluga 247 247-41 Susitna Flats 247-42 Pt. Mackenzie

247-43 Fire Island 247 -41 247 -42 247-50 Knik 247-60 Turnagin 247 -30 247 -43

EASTERN 247 -70 247 -60 247-70 Pt. Possession 247 -20 247-80 Birch Hill 247-90 #3 Bay 247 -80 247 -10 247 -90 CENTRAL DISTRICT East Side Set 244-42 -42 North Salamatof Kenai 244 245 -60 244-41 South Salamatof Section

55 244-32 North K. Beach -

244-31 South K. Beach

41 41 41

245 245 -70 41

- - -

- 244-22 Cohoe Kasilof

244 244 244 244

51 51 51 51

- - -

244 -50 - 244-21 Ninilchik Section

244 244 244 244 50 244 -32 - West Side Set 245 245-50 Little Jack Slough 10 244 -31 - 245-40 Polly Creek

246 20 - 245-30 Tuxedni Bay

246 40 245-20 Silver Salmon -

245 22 - Kustatan 244 -60 244 245-55 Big River 61 245 -80 - 245-60 West Foreland 245 -30 244 Kalgin Island -21 246-10 West Side 244 246-20 East Side Chinitna 245-10 Set

20 - 245 -90 244 -70 245-10 Drift 245 Drift Gillnet 245 -10 District Wide Corridor 244-50 Kenai 244-51 244-60 Kasilof 244-61 244-70 245-70 245-80 245-90

0 10 20 30 40 km

Figure 1.–Fishery districts and subdistricts in the Upper Cook Inlet management area.

30 km

Figure 2.–Boundaries of the drift gillnet fishery management areas 1 and 2.

10 km

Figure 3.–Boundaries of the drift gillnet fishery expanded Kenai and Kasilof sections.

Figure 4.–Bathymetry and major tide rips in Upper Cook Inlet and locations of stations along the southern offshore test fishery transect.

Expanded Kenai & Kasilof Sections 7 6 5 4 3 2 1

8 9 10 11

Drift Area 1 Boundary

10 km

Figure 5.–Locations of stations fished by the northern offshore test fishery vessel and locations of the boundaries of the expanded Kenai and Kasilof sections and drift gillnet area 1. Note: Stations 1–7 were fished in 2012–2013 and stations 2–5 and 8–11 were fished in 2014 (open circles). The expanded Kenai and Kasilof sections are represented by the solid line and drift gillnet area 1 by the dashed line.

12 15

10 2006 2010

8 10

CPUE

4 5

0 0 0 11-9 102-16 173-23 244-31 5 0 1-14 5-102 113-16 174-23 245-29 6 DatePERD in July Date in July 50 30 2007 2011 40

20 30

CPUE

CPUE 20 10 10

0 0 0 11-9 102-13 143-18 194-23 245-31 6 0 11-13 142-18 193-24 254-30 5 DatePERD in July Date in July 20 20 2008 2012 15 15

10 10

CPUE

5 5

0 0 0 1-17 8-212 13-317 184-31 5 0 11-6 7-211 123-16 174-19 205-30 6 DatePERD in July Date in July 40 40 2009 2014 30 30

20 20

CPUE

10 10

0 0 0 1-15 6-29 10-313 144-16 175-22 236-30 7 0.5 11.0-11 1.5 122.0-18 2.5 193.0-31 3.5 Date in July Date in July Figure 6.–Mean Susitna River sockeye salmon catch per unit effort (CPUEst) by date stratum along the southern OTF transect, 2006–2012 and 2014. Note: Vertical bars indicate 90% confidence intervals.

20 20 Susitna Sockeye 15 15

10 10 Mean CPUE

5 5 Mean Kenai/Susitna Sockeye CPUE

0 0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Date in July Date in July 200 50 Kenai Sockeye 40 150

30 100 20 Mean CPUE

50 10 Mean Kenai Sockeye/Coho CPUE

0 0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Date in July Date in July 80 Coho Salmon 60

40 Mean CPUE

0 0 5 10 15 20 25 30 Date in July

Figure 7.–Mean daily catch per unit effort (CPUEst,i) for Kenai and Susitna river sockeye salmon and mean daily coho salmon CPUEi pooled across all years (2006–2012 and 2014) along the southern OTF transect (left panel).

Note: Mean daily ratios of Kenai to Susitna river sockeye salmon CPUEst,i and mean daily ratios of Kenai River sockeye salmon CPUEst,i to mean daily coho salmon CPUEi are shown in the right panel. Vertical bars indicate 90% confidence intervals.

0.15 Susitna Sockeye

0.10

0.05 Mean Daily Mean RunDaily Proportions

0.00 0 5 10 15 20 25 30 Date in July 0.15 Kenai Sockeye

0.10

0.05 Mean Daily Mean RunDaily Proportions

0.00 0 5 10 15 20 25 30 Date in July 0.15 Coho Salmon

0.10

0.05 Mean Daily Mean RunDaily Proportions

0.00 0 5 10 15 20 25 30 Date in July

Figure 8.–Mean daily run proportions (PCPUEst,i) for Kenai and Susitna river sockeye salmon and coho salmon (PCPUEi) pooled across all years (2006–2012 and 2014) along the southern OTF transect. Note: Vertical bars indicate 90% confidence intervals.

1.0

0.8

0.6

0.4

0.2

Cumulative Proportion of Total CPUE 0.0 0 5 10 15 20 25 30 Date in July

Stock Mean Date Coho Salmon July 21 Kenai Sockeye Salmon July 17 Susitna Sockeye Salmon July 14

Figure 9.–Mean cumulative proportion of total PCPUEst,i for Kenai and Susitna river sockeye salmon and coho salmon PCPUEi pooled across all years (2006–2012 and 2014) along the southern OTF transect. Note: Vertical lines indicate the mean date of the runs for each stock.

80 125 70 2006 2010 100 60

50 75 40

CPUE

CPUE 30 50 20 25 10 0 0 0 11-9 102-16 173-23 244-31 5 00 11-14 5-2102 113-316 174-423 245-529 66 DatePERD in July Date in July 200 300

2007 250 2011 150 200

100 150

CPUE

100 50 50

0 0 0 1-19 102-13 14-318 194-23 245-31 6 0 1-131 14-218 19-324 25-430 5 DatePERD in July Date in July 50 200 2008 2012 40 150

30 100

CPUE 20 CPUE

50 10

0 0 0 11-7 8-212 13-317 184-31 5 0 1-61 7-112 12-163 17-194 20-530 6 DatePERD in July Date in July 200 120 2009 2014 100 150 80

100 60

CPUE

40 50 20

0 0 0 1-15 6-29 10-313 144-16 175-22 236 -30 7 0.5 11.0-11 1.5 122.0-18 2.5 193.0-31 3.5 Date in July Date in July

Figure 10.–Mean Kenai River sockeye salmon catch per unit effort (CPUEst) by date stratum along the southern OTF transect, 2006–2012 and 2014. Note: Vertical bars indicate 90% confidence intervals.

80 80 70 2006 2010 60 60 50 40 40

CPUE

CPUE 30 20 20 10 0 0 0 1-19 10-162 17-233 24-314 5 0 1-14 5-102 11-316 17-423 24-529 6 DatePERD in July Date in July 60 30 2007 2011 50 25

40 20

30 15

CPUE

20 10

10 5

0 0 0 1-19 10-213 14-318 19-423 24-531 6 0 1-113 142-18 193-24 254-30 5 Date in July PERD Date in July 70 25 60 2008 2012 20 50

40 15

CPUE 30 CPUE 10 20 5 10

0 0 0 1-17 8-122 13-173 18-431 5 0 1-61 7-112 12-163 17-419 20-530 6 Date in July Date in July 40 80 2009 2014 30 60

20 40

CPUE

10 20

0 0 0 1-51 6-92 10-133 14-164 17-522 236-30 7 0.5 11.0-11 1.5 122.0-18 2.5 193.0-31 3.5 Date in July Date in July Figure 11.–Mean coho salmon catch per unit effort by date stratum along the southern OTF transect, 2006–2012 and 2014. Note: Vertical bars indicate 90% confidence intervals.

11 20 10 2006 2010 9 8 15 7 6 5 4 10

Kenai/Susitna CPUE Kenai/Susitna

Kenai/Susitna CPUE Kenai/Susitna 3 Kenai/Susitna Sockeye CPUE 2 Kenai/Susitna Sockeye CPUE 1 5 0 1-19 102-16 173-23 244-31 5 0 11-4 5-210 113-16 174-23 245-29 6 DateDate Period in July in July DateDate Period in inJuly July 7 20 2007 2011 6 15

5 10

Kenai/Susitna CPUE Kenai/Susitna 4 CPUE Kenai/Susitna 5 Kenai/Susitna Sockeye CPUE Kenai/Susitna Sockeye CPUE

3 0 0 1-19 10-213 14-318 194-23 245-31 6 0 11-13 142-18 193-24 254-30 5 DateDate Period in July in July Date Period in July 6 20 2008 2012 5 15

Kenai/Susitna CPUE Kenai/Susitna 3 CPUE Kenai/Susitna Kenai/Susitna Sockeye CPUE Kenai/Susitna Sockeye CPUE

2 5 0 1-17 8-212 13-317 184-31 5 0 11-6 7-211 123-16 174-19 205-30 6 DateDate Period in July in July Date Period in July 20 5.5 2009 2014 5.0 15

4.5 10 4.0

Kenai/Susitna CPUE Kenai/Susitna 5 3.5

Kenai/Susitna Sockeye CPUE Kenai/Susitna Sockeye CPUE

0 3.0 0 11-5 62-9 10-313 144-16 175-22 236 -30 7 0.5 11.0-11 1.5 122.0-18 2.5 193.0-31 3.5 DateDate Period in July in July Date in July

Figure 12.–Ratios of mean Kenai to Susitna river sockeye salmon CPUEst by date stratum along the southern OTF transect, 2006–2012 and 2014.

11 20 10 2006 2010 9

U 8 U

P P 15

7 a

s 6 s

i 5 i

n n 10

e 4 e

K 3 Kenai/Susitna Sockeye Sockeye CPUE Kenai/Susitna 2 Sockeye Kenai/Susitna CPUE 1 5 0 1-91 10-162 17-233 24-314 5 0 1-41 5-102 11-163 17-234 24-295 6 DateDate Period in July in July DateDate Period in inJuly July 7 20 2007 2011

E 6 E 15

s 5 s 10

K 4 K 5 Kenai/Susitna Sockeye Sockeye CPUE Kenai/Susitna Kenai/Susitna Sockeye Sockeye CPUE Kenai/Susitna

3 0 0 1-91 10-132 14-183 19-234 24-315 6 0 1-131 14-182 19-243 25-304 5 DateDate Period in July in July Date Period in July 6 20 2008 2012

E 5 E

P P 15

s 4 s

n n 10

K 3 K Kenai/Susitna Sockeye CPUE Sockeye Kenai/Susitna Kenai/Susitna Sockeye Sockeye Kenai/Susitna CPUE

2 5 0 1-71 8-122 13-173 18-314 5 0 1-61 7-112 12-163 17-194 20-305 6 DateDate Period in July in July Date Period in July 20 5.5

2009 E

U 2014

P 5.0

E 15 C

a c 4.5

s 10

s 4.0

K 5 a

e 3.5

K Kenai/Susitna Sockeye CPUE Sockeye Kenai/Susitna

0 3.0 0 1-51 6-92 10-133 14-164 17-225 23-306 7 0.5 1-111.0 1.5 12-182.0 2.5 19-313.0 3.5 DateDate Period in July in July Date in July Figure 13.–Ratios of mean Kenai River sockeye salmon CPUEst to mean coho salmon CPUEi by date stratum along the southern OTF transect, 2006–2012 and 2014.

90 80 80 2009 70 2012 70 60 60 50 50 40

CPUE 40 CPUE 30 30 20 20 10 10 0 0 7 68 75 6.54 36 25 14 0 7 68 75 6.54 36 25 14 0 Station Station 50 200 2010 2014 40 150

30 100

CPUE 20 CPUE

50 10

0 0 7 86 75 6.54 63 52 41 0 3.5 73.0-8 2.5 62.0-6.5 1.5 41.0-5 0.5 Station Station 100 90 2011 80 70 60 50

CPUE 40 30 20 10 0 7 68 57 6.54 36 25 14 0 Station

Figure 14.–Total Susitna River sockeye salmon catch per unit effort (CPUEst) by station along the southern OTF transect, 2009–2012 and 2014. Note: In 2014, genetic stock proportions were estimated by pooling adjacent stations. Vertical bars indicate 90% credibility intervals.

120 60

100 Susitna Sockeye 80 40

CPUE

Mean CPUE 40 20

20 Kenai/Susitna Sockeye CPUE

0 CPUE Sockeye Mean Kenai/Susitna 0 7 68 75 6.54 63 52 41 0 7 86 75 6.54 63 52 41 0 Station Station 800 30 700 Kenai 600 Sockeye 20 500 400

CPUE

Mean CPUE 300 10 200

Kenai Sockeye/Coho CPUE 100 Mean Kenai Sockeye/Coho CPUE 0 0 7 68 75 6.54 36 25 14 0 7 86 75 6.54 63 52 41 0 Station Station 200 Coho 150 Salmon

100

C_CPUE Mean CPUE 50

0 7 68 75 6.54 36 25 14 0 Station

Figure 15.–Mean total Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst,s) and mean total coho salmon CPUE pooled across all years (2006–2012, 2014) by station along the southern OTF transect (left panel).

400 500 2009 2012 400 300

300 200

CPUE CPUE 200

100 100

0 0 7 68 75 6.54 63 52 41 0 7 86 75 6.54 63 52 41 0 Station Station 400 600 2010 2014 300 500

200 400

CPUE

100 300

0 200 7 68 75 6.54 36 25 14 0 3.5 73.0-8 2.5 62.0-6.5 1.5 41.0-5 0.5 Station Station 800

700 2011

600

500

CPUE 400

300

200

100 7 68 5 7 46.5 3 6 2 5 1 4 0 Station

Figure 16.–Total Kenai River sockeye salmon catch per unit effort (CPUEst,s) by station along the southern OTF transect, 2009–2012 and 2014. Note: In 2014, genetic stock proportions were estimated by pooling adjacent stations. Vertical bars indicate 90% credibility intervals.

90 50

80 2009 2012 40 70

60 30

CPUE 50 CPUE 20 40 10 30

20 0 7 86 75 6.54 63 52 41 0 7 68 75 6.54 63 52 41 0 Station Station 110 350 100 2010 2014 300 90

80 250 70

CPUE

CPUE 60 200 50 150 40 30 100 7 68 75 6.54 36 52 41 0 3.5 73.0-8 2.5 62.0-6.5 1.5 41.0-5 0.5 Station Station 100 90 2011 80 70 60 50

CPUE 40 30 20 10 0 7 68 57 6.54 36 25 14 0 Station Figure 17.–Total coho salmon catch per unit effort by station along the southern OTF transect, 2009-2012 and 2014. Note: In 2014, genetic stock proportions were estimated by pooling adjacent stations.

9 30 2009 2012 8 20 7

6 10

Kenai/Susitna Sockeye CPUE

4 0 7 68 75 6.54 63 52 41 0 7 86 75 6.54 63 52 41 0 Station Station 30 15 2010 2014

20 10

10 5

Kenai/Susitna Sockeye CPUE

0 0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 7 68 57 6.54 36 25 14 0 7-8 6-6.5 4-5 Station Station 14 13 2011 12 11 10 9 8

Kenai/Susitna Sockeye CPUE 7 6 7 68 75 6.54 36 52 41 0 Station

Figure 18.–Ratios of total Kenai to Susitna river sockeye salmon catch per unit effort (CPUEst,s) by station along the southern OTF transect, 2006–2012 and 2014. Note: In 2014, genetic stock proportions were estimated by pooling adjacent stations.

6 20 2009 2012 5 15 4

3 10

Kenai Sockeye/Coho CPUE Kenai Sockeye/Coho CPUE 2

1 5 7 68 75 6.54 63 52 41 0 7 688 7 57 6.5 6.54 6 36 5 25 4 41 0 Station Station 5 5 2010 2014 4 4 3

2 3

Kenai Sockeye/Coho CPUE Kenai Sockeye/Coho CPUE 1

2 0 7 68 75 6.54 36 25 41 0 3.5 73.0-8 2.5 62.0-6.5 1.5 41.0-5 0.5 Station Station 40 2011 30

Kenai Sockeye/Coho CPUE

0 7 68 75 6.54 36 52 41 0 Station

Figure 19.–Ratios of total Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE by station along the southern OTF transect, 2006–2012 and 2014. Note: In 2014, genetic stock proportions were estimated by pooling adjacent stations.

Susitna Sockeye Kenai Sockeye Coho Salmon 70 300 25 2012 60 250 20 50 200 15

E 40

P 150

C C 30 10 100 20 5 50 10

0 0 0 0 1-131 14-162 17-193 20-224 23-255 26-306 7 0 1-131 14-162 17-193 20-224 23-255 26-306 7 0 1-131 14-162 17-193 20-224 23-255 26-306 7 Date in July Date in July Date in July

150 600 60 2013 125 500 50

100 400 40

P 75

P 300 P 30

50 200 20

25 100 10

0 0 0 0 1-131 14-152 16-183 19-304 5 0 1-131 14-152 16-183 19-304 5 0 1-131 14-152 16-183 19-304 5 Date in July Date in July Date in July

35 150 70 2014 30 125 60

25 100 50

E E 20 E 40

P 75

C 15 C 30 50 10 20 25 5 10

0 0 0 0 1-71 8-152 16-203 2 1-244 25-305 6 0 1-71 8-152 16-203 21-244 25-305 6 0 1-71 8-152 16-203 21-244 25-305 6 Date in July Date in July Date in July

Figure 20.–Mean Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst) and mean coho salmon CPUE by date stratum along the northern OTF transect, 2012–2014. Note: Vertical bars indicate 90% confidence intervals.

75 30 Susitna Sockeye 50 20 Mean CPUE 25 10 Mean Kenai/Susitna Sockeye CPUE

0 0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Date in July Date in July 300 50 Kenai 250 Sockeye 40

200 30 150 20 Mean CPUE 100

50 Mean Kenai Sockeye/Coho CPUE

0 0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Date in July Date in July 50 Coho 40 Salmon

20 Mean CPUE

0 0 5 10 15 20 25 30 Date in July

Figure 21.–Mean daily catch per unit effort (CPUEst,i) for Kenai and Susitna river sockeye salmon and mean daily coho salmon CPUEi pooled across all years (2012–2014) along the northern OTF transect (left panel).

0.30 Susitna Sockeye

0.20

0.10 Mean Daily Mean RunDaily Proportion

0.00 0 5 10 15 20 25 30 Date in July 0.30 Kenai Sockeye

0.20

0.10 Mean Daily Mean RunDaily Proportion

0.00 0 5 10 15 20 25 30 Date in July 0.20 Coho Salmon 0.15

0.10

0.05 Mean Daily Mean RunDaily Proportion

0.00 0 5 10 15 20 25 30 Date in July

Figure 22.–Mean daily run proportions (PCPUEst,i) for Kenai and Susitna river sockeye salmon and mean daily coho salmon run proportions (PCPUEi) pooled across all years (2012–2014) along the northern OTF transect. Note: Vertical bars indicate 90% confidence intervals.

1.0

0.8

0.6

0.4

0.2

Cumulative Proportion of Total CPUE 0.0 0 5 10 15 20 25 30 Date in July

Stock Mean Date Coho Salmon July 23 Kenai Sockeye Salmon July 16 Susitna Sockeye Salmon July 15

Figure 23.–Mean cumulative proportion of total PCPUEst,i for Kenai and Susitna river sockeye salmon and coho salmon (PCPUEi) pooled across all years (2012–2014) along the northern OTF transect. Note: Vertical lines indicate the mean dates of the runs for each stock.

Kenai/Susitna Sockeye CPUE Kenai Sockeye/Coho CPUE 30 50 2012 40 20 30

20 10

Kenai Sockeye/Coho CPUE 10

Kenai/Susitna Sockeye CPUE

0 0 0 1-131 14-162 17-319 204-22 235-25 266-30 7 0 1-113 142-16 173-19 204-22 235-25 266-30 7 Date in July Date in July 15 20 2013 15 10

5 5

Kenai Sockeye/Coho CPUE

Kenai/Susitna Sockeye CPUE

0 0 0 1-131 14-215 16-318 19-430 5 0 1-113 142-15 163-18 19-430 5 Date in July Date in July 15 30 2014

10 20

5 10

Kenai Sockeye/Coho CPUE

Kenai/Susitna Sockeye CPUE

0 0 0 1-17 8-215 16-203 21-424 25-530 6 0 11-7 8-215 16-320 214-24 255-30 6 Date in July Date in July

Figure 24.–Ratios of mean Kenai to Susitna river sockeye salmon catch per unit effort (CPUEst) by date stratum (left panel), and ratios of mean Kenai River sockeye salmon CPUEst to mean coho salmon CPUEi by date stratum (right panel) along the northern OTF transect 2012–2014.

Susitna Sockeye Kenai Sockeye Coho Salmon 200 1500 70

2012 60 150 50 1000 40 100

CPUE

CPUE CPUE 30 500 20 50 10

0 0 0 0 6-17 25 34 43 15-2 6 0 6-17 52 43 34 1-52 6 0 61-7 25 43 43 15-2 6 Station Station Station

150 1000 100 2013 800 80 100 600 60

CPUE CPUE

CPUE 400 40 50

200 20

0 0 0 0 61-7 25 34 4 3 15-2 6 0 61-7 25 43 43 15-2 6 0 61-7 25 43 43 15-2 6 Station Station Station

100 500 100 2014 80 400 80

60 300 60

CPUE

CPUE 40 200 40

20 100 20

0 0 0 0 5&81 4&92 3&103 2&114 5 0 5&81 4&92 3&103 2&114 5 0 5&81 4&92 3&103 2&114 5 Station Station Station

Figure 25.–Total Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst,s) and total coho salmon CPUE by station along the northern OTF transect, 2012–2014. Note: Vertical bars indicate 90% credibility intervals. Total CPUEs are plotted together for paired stations along the upper (solid circles) and lower (solid squares) Kalgin Island transects sampled in 2014.

160 50 140 Susitna Sockeye 40 120 100 30 80

Mean CPUE Mean 60 20 40 10 20

Mean Kenai/Susitna Sockeye CPUE Kenai/Susitna Sockeye Mean 0 0 5 54 43 32 11-2 0 5 45 43 23 11-2 0 Station Station 1200 40 Kenai 1000 Sockeye 30 800

600 20

Mean CPUE Mean 400 10 200

Mean Kenai Sockeye/Coho CPUE Mean 0 0 5 54 43 23 11-2 0 5 45 43 23 11-2 0 Station Station 100 90 Coho 80 Salmon 70 60 50 40

Mean CPUE Mean 30 20 10 0 5 54 43 23 11-2 0 Station

Figure 26.–Mean total Kenai and Susitna river sockeye salmon catch per unit effort (CPUEst,s) and mean total coho salmon CPUE pooled across all years (2012–2014) by station along the northern OTF transect (left panel).

Note: Mean ratios of total Kenai to Susitna river sockeye salmon CPUEst,s and mean ratios of total Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE pooled across all years (2012–2014) by station along the northern OTF transect (right panel). Data from comparable stations (i.e., stations 5 and 8, 4 and 9, 3 and 10, and 2 and 11) sampled along the upper and lower Kalgin Island transects in 2014 were pooled in this analysis. Vertical bars indicate 90% confidence intervals.

Kenai/Susitna Sockeye CPUE Kenai Sockeye/Coho CPUE 50 30 2012 40 20 30

20 10

Kenai Sockeye/Coho CPUE Kenai Sockeye/Coho CPUE 10 Kenai/Susitna Sockeye CPUE

0 0 0 61-7 25 43 34 15-2 6 0 61-7 25 34 34 15-2 6 Station Station 30 40 2013 30 20

10 10

Kenai Sockeye/Coho CPUE

Kenai Sockeye/Coho CPUE Kenai/Susitna Sockeye CPUE

0 0 0 661--77 525 434 3 43 11-5-22 6 0 61-7 25 43 34 15-2 6 Station Station 10 40 9 2014 8 30 7 6 20 5 4 10

Kenai Sockeye/Coho CPUE

Kenai/Susitna Sockeye CPUE 3 2 0 0 5&81 4&9 4&92 3&103 2&11 2&114 5 0 5&81 4&92 3&103 2&114 5 Station Station

Figure 27.–Ratios of total Kenai to Susitna river sockeye salmon catch per unit effort (CPUEst,s) and ratios of total Kenai River sockeye salmon CPUEst,s to total coho salmon CPUE by station along the northern OTF transect, 2012–2014. Note: Total CPUE ratios were plotted together for paired stations along the upper (solid circles) and lower (solid squares) Kalgin Island transects sampled in 2014.