title
Estimates of commercial harvest and escapement of coho salmon stocked into northern Cook Inlet streams, 1993
author
Array ( [0] => Hoffmann, A. G. J. J. Hasbrouck )
abstract
Coho salmon Oncorhynchus kisutch marked as juveniles with coded wire tags and adipose finclips in 1991 and 1992 were released into several freshwater systems of Northern Cook Inlet. Marked coho salmon were recovered in 1993 from commercial fisheries and escapements. Escapement samples were used to assess straying and the proportion of marked fish returning to each system. Commercial harvest data and recoveries of marked fish from the commercial harvest were used to estimate the harvest of stocked coho salmon from these systems in the Upper Cook Inlet commercial fisheries. During the dates of the catch sampling program a total of 117,924, 39,333, and 61,870 coho salmon were harvested from the Central District drift net fishery, Central District Upper Subdistricts (eastside) set net fishery, and Northern District set net fishery, respectively. Coho salmon from the hatchery stocking programs contributed an estimated 8,922 fish (7.6%) to the Central District drift net fishery, 1,783 fish (4.5%) to the Central District eastside set net fishery, and 6,180 (10%) to the Northern District set net fishery. Escapement counts of 382 coho salmon in Ship Creek and 2,376 coho salmon in Campbell Creek exceeded the biological escapement goal of 200 coho salmon in each stream. Estimates from the Statewide Harvest Survey show that effort and harvest increased in 1993 relative to the historic average at Campbell and Bird creeks, likely due to the return of stocked coho salmon, and remained at the same levels in Ship Creek. Recovery of 341 coho salmon with decodable tags from the escapement in Northern Cook Inlet streams indicated that hatchery-reared coho salmon did not stray into Campbell or Jim creeks or the Little Susitna River. Coho salmon stocked into Campbell Creek strayed into Ship Creek at a rate greater than 5%.
date
1994-11-01
organization
ADF&G Division of Sport Fish
species
Array ( [0] => Coho Salmon )
file_path
https://grey-lit.s3.wasabisys.com/estimates-of-commercial-harvest-and-escapement-of-coho-salmon-stocked-into-northern-cook-inlet-strea.pdf
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content
Fishery Data Series No. 94-45 Estimates of Commercial Harvest and Escapement of Coho Salmon Stocked into Northern Cook Inlet Streams, 1993 bY Andrew G. Hoffmann and James J. Hasbrouck November 1994 Alaska Department of Fish and Game Division of Sport Fish FISHERY DATA SERIES NO. 94-45 ESTIMATES OF COMMERCIAL HARVEST AND ESCAPEMENT OF COHO SALMON STOCKED INTO NORTHERN COOK INLET STREAMS, 1993' BY Andrew G. Hoffmann and James J. Hasbrouck Alaska Department of Fish and Game Division of Sport Fish Anchorage, Alaska November 1994 1 This investigation was partially financed by the Federal Aid in Sport Fish Restoration Act (16 U.S.C. 777-777K) under Project F-10-9, Job No. E-2-5. The Fishery Data Series was established in 1987 for the publication of technically oriented results for a single project or group of closely related projects. Fishery Data Series reports are intended for fishery and other technical professionals. Distribution is to state and local publication distribution centers, libraries and individuals and, on request, to other libraries, agencies, and individuals. This publication has undergone editorial and peer review. The Alaska Department of Fish and Game administers all programs and activities free from discrimination on the basis of sex, color, race, religion, national origin, age, marital status, pregnancy, parenthood, or disability. For information on alternative formats available for this and other department publications, contact the department ADA Coordinator at (voice) 907-465-4120, or (TDD) 907-465-3646. Any person who believes s/he has been discriminated against should write to: ADF&G, P.O. Box 25526, Juneau, AK 99802-5526; or O.E.O., U.S. Department of the Interior, Washington, DC 20240. TABLE OF CONTENTS Page LIST OF TABLES............................................... ii LIST OF FIGURES.............................................. iii LIST OF APPENDICES........................................... iv ABSTRACT..................................................... 1 INTRODUCTION................................................. 2 OBJECTIVES................................................... 6 Escapement ............................................. 6 Commercial Catch Assessment ............................ 6 METHODS...................................................... 7 Study Design ........................................... 7 Data Collection ........................................ 7 Stocking and Marking ............................... 7 Escapement ......................................... 8 Commercial Catch Sampling ......................... 9 Data Analysis .......................................... 10 Straying ........................................... 10 Estimating Commercial Harvest of Stocked Coho Salmon ........................................ 10 RESULTS...................................................... 13 Escapement ............................................. 13 Straying ............................................... 15 Returns ................................................ 15 Commercial Harvest of Stocked Coho Salmon .............. 15 DISCUSSION................................................... 21 Sport Fishery .......................................... 21 Escapement ............................................. 30 Straying ............................................... 30 Tag Loss ............................................... 30 Commercial Catch Assessment ............................ 31 ACKNOWLEDGMENTS.............................................. 32 LITERATURE CITED............................................. 32 APPENDIX A................................................... 35 -i- LIST OF TABLES Table 1. 2. 3. 4. 5. 6. 7. Summary of coded wire tagging data by release site for coho salmon reared at Big Lake, Elmendorf, and Fort Richardson hatcheries and stocked in Cook Inlet in 1992 (Peltz and Starkey 1993....................... Number sampled (n) and percent retention (%I for coded wire tagged coho salmon at release and recovery in the escapement of Northern Cook Inlet streams, 1993......................................... Summary of sampling efforts and escapement counts of coho salmon at weirs in sys terns in Northern Cook Inlet, 1993. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Number of coded wire tagged coho salmon recovered from the escapement by release site in Upper Cook Inlet, 1993........................................... Total harvest of coho salmon in commercial fisheries of Upper Cook Inlet in 1993 except for set net fisheries in statistical areas 245 and 246............ Harvest of coho salmon from sampled commercial fisheries of Upper Cook Inlet in 1993................. Estimates of harvest (nl) and variance [V(nl)] by release site of stocked coho salmon in the commercial fishery in Upper Cook Inlet, 1993.......... 5 12 14 16 19 20 23 -ii- LIST OF FIGURES Figure 1. 2. 3. 4. 5. 6. 7. 8. 9. Map of Upper Cook Inlet commercial salmon fishing districts and statistical areas........................ Map of Northern Cook Inlet urban areas................. Distribution of coho salmon returns among commercial and sport fisheries and the escapement in three stocked streams........................................ Sport harvest and effort from 1988 to 1993 in Anchorage urban streams (Campbell, Ship and Bird creeks) stocked with coho salmon (Mills 1989-1994)..... Distribution of coho salmon harvest and hatchery contribution among three UC1 fisheries, Central District drift net (CDD), Central District set net (CDS), and Northern District set net (NDS), 1993....... Portion of Upper Cook Inlet coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample........... Portion of Central District drift, coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample................................................. Portion of Central District set net coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample................................................. Portion of Northern District set net, coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample................................................. 3 4 17 18 22 26 27 28 29 -iii- LIST OF APPENDICES Appendix PaRe A. Daily escapement counts of coho salmon from weirs on Campbell and Ship creeks, 1993......................... 36 -iv- ABSTRACT Coho salmon Oncorhynchus kisutch marked as juveniles with coded wire tags and adipose finclips in 1991 and 1992 were released into several freshwater systems of Northern Cook Inlet. Marked coho salmon were recovered in 1993 from commercial fisheries and escapements. Escapement samples were used to assess straying and the proportion of marked fish returning to each system. Commercial harvest data and recoveries of marked fish from the commercial harvest were used to estimate the harvest of stocked coho salmon from these systems in the Upper Cook Inlet commercial fisheries. During the dates of the catch sampling program a total of 117,924, 39,333, and 61,870 coho salmon were harvested from the Central District drift net fishery, Central District Upper Subdistricts (eastside) set net fishery, and Northern District set net fishery, respectively. Coho salmon from the hatchery stock- ing programs contributed an estimated 8,922 fish (7.6%) to the Central District drift net fishery, 1,783 fish (4.5%) to the Central District eastside set net fishery, and 6,180 (10%) to the Northern District set net fishery. Escapement counts of 382 coho salmon in Ship Creek and 2,376 coho salmon in Campbell Creek exceeded the biological escapement goal of 200 coho salmon in each stream. Estimates from the Statewide Harvest Survey show that effort and harvest increased in 1993 relative to the historic average at Campbell and Bird creeks, likely due to the return of stocked coho salmon, and remained at the same levels in Ship Creek. Recovery of 341 coho salmon with decodable tags from the escapement in Northern Cook Inlet streams indicated that hatchery-reared coho salmon did not stray into Campbell or Jim creeks or the Little Susitna River. Coho salmon stocked into Campbell Creek strayed into Ship Creek at a rate greater than 5%. -l- INTRODUCTION Coho salmon Oncorhynchus kisutch are distributed throughout Upper Cook Inlet (UCI) and support the largest sport (Mills 1993) and the second largest commercial harvest (Meyer et al. Unpublished) in Alaska. Large, directed sport fisheries occur throughout UCI. In 1992, UC1 contributed 55% of the statewide harvest and 80% of the southcentral sport harvest of coho salmon (Mills 1993). The largest sport fisheries for coho salmon occur on the Kenai, Susitna, and Little Susitna rivers. The primary commercial fisheries of coho salmon in UC1 are the Central District drift gill net, the Central District Upper Subdistrict (eastside) set gill net, and the Northern District set gill net fisheries (Figure 1). Since 1966, the average harvest by fishery has been: drift (168,838 fish, 43%); Upper Subdistrict (45,677 fish, 15%); and Northern District (75,325 fish, 22%). Other set and drift gill net commercial fisheries compose the remaining 20% of the harvest. The Northern Cook Inlet (NC11 urban area extends from Ingram Creek in Turnagain Arm north to the town of Houston (Figure 2). Recreational fishing effort in this area increased from an average of 178,000 angler-days from 1977 through 1985 to over 260,000 angler-days annually from 1986 through 1990 (Mills 1979-1991). Anglers fishing in the NC1 urban area target five species of Pacific salmon Oncorhynchus, rainbow trout 0. mykiss, Dolly Varden/Arctic char Salvelinus malma, and Arctic grayling Thymallus arcticus. Sport fisher- ies for these species are supported by both wild and hatchery-produced stocks. As the population of the NC1 urban area increases, the demand for sport fishing opportunities for anadromous salmon grows. Wild stocks are becoming fully utilized; therefore, as effort increases hatchery-produced stocks play an increasingly important role in supporting the growing sport fisheries. Stocking of anadromous fish has occurred in NC1 since the 197Os, however, a successful fishery was not developed until the mid 1980s with the success of the chinook and coho salmon fisheries in Ship Creek. To increase recreational sport fishing opportunities in the NC1 urban area, a coho salmon smolt stock- ing program was initiated in several NC1 urban area streams in 1992. The guidelines for determining the success of this stocking program are that it be cost-effective, have minimal (if any) impact on other wild stocks or fisher- ies, and the sport harvest of these stocked fish will not compromise the historic levels of natural spawning escapement in the stocked streams. The original urban stocking program involved stocking coho salmon smolt into seven NC1 streams: Little Susitna River and Fish, Cottonwood, Wasilla, Ship, Campbell, and Bird creeks. Fish, Wasilla, and Cottonwood creeks were stocked with smolt raised at the Big Lake Hatchery, but this facility closed in July of 1993. The closure reduced the scope of this program, after 1993, to stock- ing smolt into the four remaining NC1 streams. A portion of the smolt released in each stream were marked with an adipose finclip and coded wire tag, with a unique tag code used for each stream (Table 1, Peltz and Starkey 1993). The stocking program should increase recreational angling opportunity and attract additional recreational fishing participation. The program is targeted to increase recreational angler effort by 20,000 angler-days and harvest by 10,000 coho salmon among all streams. Increases in recreational angler effort should result in increased economic benefit to the NC1 urban -2- Susitna Fiats Pt. Mackenzie Pt. Possession EAST SIDE SET 24440 Salamatof 244-30 Kalafonski Beach 244-22 Cohoe 244-21 Ninilchik WEST SIDE SET 245-50 Little Jack Slough 245-40 Polly Creek 245-30 Tuxedni Bay 245-20 Sllvar Salmon KUSTATAN 245-55 Big Rwar 245-60 West Foreland KALGIN ISLAND 246-l 0 West Side 246-20 East Side CHINITNA 245-l 0 Set 245-l 0 Drift DRIFT 244-50 244-60 244-70 245-70 245-60 Figure 1. Map of Upper Cook Inlet commercial salmon fishing districts and statistical areas. -3- Figure 2. Map of Northern Cook Inlet urban areas. -4- Table 1. Summary of coded wire tagging data by release site for coho salmon reared at Big Lake, Elmendorf, and Fort Richardson hatcheries and stocked in Cook Inlet in 1992 (Peltz and Starkey 1993). Big Lake Hatchery Elmendorf Hatchery Fort Richardson Hatchery Cottonwocd Wasilla Fish Ship Nancy Bird Carpbell Creek Creek Creek Creek Houston Lake Creek Creek 31-20-02 31-20-04 31-20-03 31-20-05 Tag Codes 31-20-08 31-20-10 31-20-12 31-19-63 31-20-09 31-20-11 31-20-13 31-20-01 31-20-07 31-20-06 Total marked and taggeda Mortalitiesb 45,500 10,159 45,044 896 46,651 1,113 44,807 721 22,073 189 21,924 326 45,173 270 43,912 231 Marked fish released 35,341 44,148 45,538 44,086 21.884 21.598 44,903 43,681 Tag retention sarrple size Tag retention at release 1,890 1,786 1,798 1,723 934 1,684 1,717 93.2% 95.1% 95.8% 87.2% 89.4% 89.0% 83.8% 90.3% Tagged fish released Estimated total fish released= 32,938 41,985 43,625 38,443 19,564 19,222 37,629 39,444 158,459 12.1% 2/25-27 95,377 39.5% 3/9-13 97,076 40.6% 3/16-19 53,900 61.1% 3/4-20 76,315 55.0% 4/3-15 74,953 58.2% 3/20-4/3 67,178 57.2% l/29-2/7 154,466 12.7% 2/27-3/9 Percent tagged Tagging dates Date of tag retention check Days elapsedd 5/19-20 67 5/19-20 61 6/18 90 6/18 64 6/18 76 5/18-19 101 5/19-20 71 5/19-20 82 a Marked fish refers to fish with an adipose finclip and tagged fish refers to fish with an adipose finclip and a coded wire tag. b An estimated 7,368 tagged smolt destined for Cottonwood Creek were not released due to their small size. c The release number is the mark/recapture estimate. d Days elapsed between the last day of tagging and the day tag retention was checked. area. Estimates of sport angling effort and harvest from the Statewide Harvest Survey were used to evaluate the success of the NC1 urban stocking program. Despite the size and importance of UC1 sport and commercial fisheries, no comprehensive program assessed the status of contributing stocks (Meyer et al. Unpublished). Coho salmon are harvested in commercial fisheries largely as a mixed-stock bycatch with no quantifiable information of stock origin. Large, directed sport fisheries of coho salmon occur throughout UCI. Estimates of harvest are available for many of these sport fisheries (Mills 19931, but there is no stock-specific information on the magnitude of total returns, exploitation rates, or spawning escapements. An assessment program was developed by the Alaska Department of Fish and Game, Division of Sport Fish in 1991 to evaluate the coho salmon stocks of UC1 (Meyer et al. Unpublished). This program was designed to estimate the harvest of selected wild and hatchery-reared coho salmon stocks to the commercial fishery in UC1 and to evaluate the success of the hatchery coho salmon stocking programs in NCI. The overall program consists of five distinct but interrelated components: (1) the estimation of commercial harvest in UC1 of stocked fish; (2) the m ar ing of juvenile coho salmon and inriver recovery of k' marked adults, and estimation of the commercial harvest in UC1 of wild stock coho salmon from the Kenai River; (3) the estimation of the sport harvest, enumeration of the escapement, and evaluation of the coho salmon stocking program in the Little Susitna River; (4) the enumeration of the escapement of coho salmon at Jim Creek; and (5) the production, marking and release of coho salmon smolt by the hatcheries. This report covers the first component above. Other components of the program are reported elsewhere (Carlon 1992; Carlon and Hasbrouck In prep; Bartlett 1994, Unpublished; Peltz and Starkey 1993). OBJECTIVES Objectives for the 1993 urban coho salmon assessment are divided into two grow, escapement and commercial catch sampling, as listed below. Escapement 1. Enumerate the coho salmon spawning escapement through weirs at Campbell and Ship creeks and collect heads from adipose finclipped fish. 2. Test the null hypothesis that hatchery-produced coho salmon stocked in NC1 streams do not stray from the stream of origin into Ship and Campbell creeks upon return. Commercial Catch Assessment 3. Estimate the harvest of hatchery-produced coho salmon stocked in the NC1 urban area streams in the Northern District set net fishery, the Central District Upper Subdistrict (eastside) set net fishery, and the Central District drift net fishery. -6- Data collected from other components of the overall UC1 coho salmon assessment program are also pertinent to this project. In this report, estimates of the commercial harvest of coho salmon stocked in the Little Susitna River are presented. In addition, coho salmon were examined for adipose clips from the escapement and sport harvest in the Little Susitna River, and from the escape- ment passing the weir on Jim Creek. Coded wire tag data from these projects were used in this report to assess straying. The coho salmon hatchery stock- ing program at the Little Susitna River is evaluated in a separate project (Bartlett 1994). Data collected at Jim Creek was part of the coho and sockeye salmon assessment studies conducted by Bartlett (Unpublished). METHODS Study Desipn The overall goal of the urban stocking program is to increase angler participation through increased opportunities to fish for coho salmon. The Statewide Harvest Survey is used to evaluate whether targeted increases in angler effort and harvest are achieved. However, if the returns are poor, then the cause of the poor returns must be determined. Poor returns of adults to freshwater sport fishing areas could result from low smolt survival and/or high fishing mortality prior to reaching fresh water. This project estimates the harvest of hatchery-produced coho salmon stocks in the common property, mixed-stock commercial fishery and estimates the return of stocked fish to particular streams. Results should establish if returns are harvested prior to reaching the terminal areas. Data will also be provided to the hatchery stocking program to assess the impact of smolt production and release on the marine survival of smolt and on the abundance of the adult return. The basic study design involved marking coho salmon smolt (or fingerling in some stockings in the Little Susitna River prior to 1992) with a coded wire tag and an adipose finclip. Marked fish were released with unmarked fish in 1992 and emigrated into marine waters. Catch sampling programs of adult coho salmon in the commercial harvest and the escapement were conducted in 1993 to recover marked fish. Heads were collected from clipped fish and sent to the Department of Fish and Game Coded Wire Tag Laboratory in Juneau (Tag Lab). The Tag Lab determined if a tag was present and decoded the tag number of fish retaining the tag. Catch sampling data were used to test assumptions of the model to estimate harvest and to determine the stratification necessary to provide an unbiased estimate of contribution with the best precision. Final estimates of contribution and their variances were then calculated. Data Collection Stocking and Marking: Coho salmon from the Little Susitna River were reared at Ft. Richardson and Big Lake hatcheries. Coho salmon reared at Ft. Richardson Hatchery were stocked into Bird Creek, Campbell Creek, and the Little Susitna River at Houston and Nancy Lake in May 1992 (Peltz and Starkey 1993). Fish from Big Lake Hatchery were released into Cottonwood, Fish, and Wasilla creeks in -7- June 1992. Coho salmon reared in these hatcheries had also been stocked into Meadow Creek and Nancy Lake as fingerlings in 1990 and stocked into the Little Susitna River at Nancy Lake and Houston as smolt in 1991. Coho salmon from Ship Creek were reared at Elmendorf Hatchery and released as smolt into Ship Creek in May 1992. The number of coho salmon stocked in 1992 as part of the NC1 urban stocking program ranged from 53,900 at Cottonwood Creek to 97,100 at Campbell Creek (Table 1; Peltz and Starkey 1993). Approximately 155,000 were stocked at each location (Houston and Nancy Lake) of the Little Susitna River in 1992. Coho salmon were marked with a coded wire tag and adipose finclip from January to April 1992. The proportion of marked fish varied among hatcheries. Approxi- mately 58% of each of the three release groups from Big Lake Hatchery and 57% of the coho salmon released from Elmendorf Hatchery were marked. At Fort Richardson Hatchery, 40% of the coho salmon released into Bird Creek and Campbell Creek and approximately 12% of the coho salmon released into the Little Susitna River at Houston and Nancy Lake were marked. Details of the rearing, marking, and release of hatchery stocked coho salmon are presented by Peltz and Starkey (1993). Escapement: Total counts of coho salmon above the inriver sport fishery were made on Ship and Campbell creeks from mid-July through mid-September 1993. A weir constructed on Campbell Creek near Folker Street and the live-box on the Ship Creek fish pass were used to enumerate fish migrating upstream. These weirs were operated 24 hours a day and all coho salmon were examined for missing adipose fins. Fish for brood stock were also collected at Ship Creek. A daily and cumulative count was made of all coho salmon passing these weirs and of coho salmon missing the adipose fin. Counts of other salmon species were also recorded. Escapement goals of 200 naturally spawning coho salmon have been established for both streams. To ensure the escapement goal was attained in both systems, only a portion of the coho salmon with an adipose clip were collected. Given the expected number of coho salmon in the escapement of each stream and the need to collect 60 coho salmon with coded wire tags from each stream to test the hypothesis of straying, heads were collected from every fourth finclipped fish at Campbell Creek and every eighth finclipped fish at Ship Creek. The heads of all finclipped coho salmon collected for brood stock at the Ship Creek weir were also collected. A uniquely numbered cinch strap was affixed to the head (jaw) and each head was placed in an individual clear plastic bag with the cinch strap number visible. Data recorded included: date, creek, number of coho salmon examined, number of coho salmon missing the adipose fin, and the cinch strap number of each head collected. All heads with cinch straps were returned to the Anchorage ADF&G office and frozen until shipment to the Tag Lab. The dam in Ship Creek was observed during peak high tides because of concern that coho salmon may get over the dam during these times. Weirs were also constructed on the Little Susitna River (Bartlett 1994) and Jim Creek (Bartlett Unpublished) to enumerate the escapement and examine coho salmon for missing adipose fins. No coho salmon were stocked in Jim Creek so no marked fish were expected to be observed in the return. -8- Commercial Catch Sampling: Catch sampling of the UC1 coho salmon harvest was conducted from mid-July to mid-September 1993 when the majority of the coho salmon harvest occurred. Coho salmon were usually sampled at processors, on sorting lines or from totes, but at times were sampled aboard tenders or at buying stations. All regular commercial fishing periods (7:OO a.m. to 7:00 p.m., Mondays and Fridays) were sampled. Additional fishing periods were sampled as time and budget allowed. There were no extra periods in the Northern District or the Central District Upper Subdistricts set net fisheries after 15 August. Coho salmon delivered to the processors were enumerated using tally-whackers and examined for the absence of adipose fins. As many fish as possible were examined from deliveries during the sampling shift. All adipose finclipped coho salmon observed were retrieved, the head removed, and a uniquely numbered cinch strap affixed to the head. Processors usually wanted to record the total weight of all fish delivered, therefore, finclipped coho salmon were weighed before the head was collected. Each head was placed in an individual clear plastic bag with the cinch strap number visible. Data recorded included the date, processor, delivery, statistical area, number of coho salmon examined, number of coho salmon missing the adipose fin, number of heads collected from coho salmon missing the adipose fin, and the cinch strap number of each head collected. All coho salmon heads with cinch straps were returned to the ADF&G offices in Soldotna or Anchorage. The heads were frozen immediately and shipped each week to the Tag Lab to remove and decode the tags. After each commercial fishing period, the total commercial harvest of coho salmon for UC1 by statistical area was obtained from the Division of Commercial Fisheries Management and Development (CFMD) in Soldotna. Final harvest data for the season were obtained approximately 2 months after the commercial season ended. In general, totes sampled from set net harvested coho salmon were pure loads of fish harvested from a single statistical area. Totes of coho salmon sampled from the Central District drift net fishery were a mixture of fish harvested in different statistical areas. Total number of coho salmon harvested and the number of harvested coho salmon purchased by each processor by date and statistical area were retrieved from the CFMD fish ticket database on 2 March 1994. Thus, for samples from set net harvested coho salmon we knew the total harvest by statistical area and date. For each date-statistical area-processor combination, the number of harvested coho salmon purchased, the number examined, and the number with a missing adipose fin were also known. We had the same data for coho salmon harvested in the Central District drift net fishery except the harvest and number purchased were the sums of statistical areas 244-50, 244-60, 244-70, 245-70, 245-80, and 245-90. Northern District. Catches processed in the Anchorage area during 1993 were comprised entirely of Northern District fish, with sampling effort initially concentrated at two processors: Whitney Foods and Laona Processing. Cook Inlet Processors (CIP) in Nikiski was sampled regularly for set net harvest from statistical areas 247-70, 247-80, and 247-90 by personnel from Anchorage through mid-August and by technicians from Soldotna through September. Sampling was also conducted at the Icicle plant in Homer for two periods in mid-August. Inseason changes in buying patterns in the Anchorage area (Laona -9- closed) lead to the sampling of two additional processors in Anchorage, Great Pacific and Sahalee. Additional catch sampling was periodically conducted onboard tenders. Technicians contacted the processors throughout the season to coordinate sampling logistics and to ensure that all possible fish were examined. The Northern District catch sampling in Anchorage was conducted from 16 July through 20 August when all processors closed for the season. Sampling was conducted at the CIP plant in Nikiski until 13 September. Central District. Commercial catch sampling in the Soldotna area included harvests from the drift net, the Upper Subdistrict set net, and the afore- mentioned Northern District set net fisheries. Sampling was conducted at several fish processing facilities under the supervision of the CFMD biolo- gists. Sampling of the drift net harvest was concentrated at Wards Cove Packing, Inlet Salmon, Kenai Packers, Salamatof Seafoods, Dragnet Fisheries, and Trans-Aqua International. The Upper Subdistrict set net harvest was sampled by contacting buying stations for the major fish processing plants in the Soldotna/Kenai area including: Carlson Seafoods, Cook Inlet Processing, Dragnet Fisheries, Icicle Seafoods, Inlet Fisheries, Keener Packing, Kenai Packers, Royal Pacific Fisheries, Salamatof Seafoods, Trans-Aqua Internation- al, and Wards Cove Packing. The Central District drift net fishery was sampled by six port samplers from 9 July through 30 August. The Upper Subdistrict set net fishery was sampled by four port samplers from 23 July through 30 August. Data Analysis Straying: There were concerns that coho salmon released as part of the urban stocking program would not adequately imprint to the release stream and might stray into a different stream upon return. A chi-squared statistic was used to test the hypothesis that stocked coho salmon stray from the stream of stocking upon return such that a stray rate of 0.05 could be detected 95% of the time at /3 = 0.05. Only recoveries from the adult escapement at Ship and Campbell creeks were used for this test. Coho salmon were also sampled in the escapement at the Little Susitna River and Jim Creek (Bartlett 1994, Unpublished). The number of coho salmon recovered at the weirs on Ship and Campbell creeks with coded wire tags which where not stocked in these respective systems were used to test the hypothesis regarding straying. If all 60 tagged coho salmon recovered at the weir were originally stocked in that creek, then straying rate was likely < 5%. If one or more of the 60 coho salmon was originally stocked in a different creek, then straying rate was likely 2 5%. Estimating Commercial Harvest of Stocked Coho Salmon: Estimating the harvest of a cohort of fish in a commercial fishery required estimating the proportion of marked fish. The proportion of tagged coho salmon stocked at each location was determined prior to release and was treated as a known constant (Peltz and Starkey 1993). However, if significant -lO- tag loss occurred after release, then the proportion of tagged coho salmon was estimated by sampling the inriver return of adults. A chi-squared statistic was used to test if the tag retention of adults was the same as that of release. To conduct the test, only adult recovery data from the escapement at Campbell and Ship creeks and the Little Susitna River were used. Release data from Houston and Nancy Lake were pooled to get an overall estimate of tag retention at release of fish stocked into the Little Susitna River. Harvest of a single cohort (release group) of fish in a stratum was estimated by (Clark and Bernard 1987): ,. n1 = m 1aPm c m [email protected] (1) where: ml m2 al a2 N n2 4 8 number of heads with coded wire tags detected, number of coded wire tags found and decoded, number of heads collected in the sample from fish with a missing adipose fin, number of heads that arrived at the Tag Lab, total number of fish in the harvest, number of fish in the harvest examined for a missing adipose fin, number of decoded coded wire tags from the cohort, and proportion of the cohort marked and released with coded wire tags. This estimator is statistically unbiased when sampling is from a simple random or pseudo-random process (Clark and Bernard 1987). When the harvest (N) and the proportion marked (0) are known without error an unbiased estimate of the variance is: v&) = Values of harvest from the fish ticket database are assumed known and measured without error. between 2release We found no significant difference in tag retention (Table 2) from the hatchery and adult escgpement samples at Campbell Creek (x = 0.35, df = 1, P = 0.55), Ship Creek (x = 2.21, df = 1, P = 0.14), or the 1992 smolt releases into the Little Susitna River (x2 = 0.18, df = 1, 1 Although not significantly different, point estimates of tag retention as adults were always less than those at release. This comparison should continue to be investigated. -ll- Table 2. Number sampled (n) and percent retention (%> for coded wire tagged coho salmon at release and recovery in the escapement of Northern Cook Inlet streams, 1993. Releasea Recovery Escapement System n % n % Ship Creek 1,723 87 44 80 Campbell Creek 1,717 90 161 89 Bird Creek 1,674 84 -b _ Little Susitna River 1.776 89 177 88 a Data from Peltz and Starkey 1993. b No escapement data collected from Bird Creek. -12- P = 0.67). Therefore, values of 8 at the time of release (Peltz and Starkey 1993) were used and treated as known values measured without error. Harvest of each cohort was stratified by date and statistical area for each fishery. Statistical area was unknown when catch sampling the Central District drift net fishery, so harvest of this fishery was stratified only by date. The total harvest of a cohort in a fishery was estimated by summing the estimates among the strata. Variance of the total estimate was also calcu- lated by summing the variances of the strata estimates since strata were assumed independent and there were no additional covariance terms. We investigated whether data could be pooled among dates within each fishery and among statistical areas of set net harvested coho salmon. Total harvest and its variance were estimated with the data stratified and with the data pooled. For example, to determine if two statistical areas could be pooled, estimates were calculated with the data stratified by statistical area and then calculated with data from the two statistical areas combined. If the estimates of harvest were not significantly different and pooling the data improved the precision of the estimate, the data were pooled. Otherwise, estimates were stratified. We also examined if the data should be further stratified by processor. We calculated a series of chi-square statistics to test the hypothesis that the marked:unmarked ratio (i.e. the number of coho salmon with coded wire tags from a cohort to the total number of coho salmon examined for adipose clips) was not different among processors purchasing coho salmon in the different fisheries. Although some differences were found among processors, the propor- tion marked generally ranged only between 0.005-0.05 for predominant cohorts among all processors in all fisheries. We concluded these differences were too small to seriously bias the estimates and pooled catch sampling data among processors. RESULTS Escapement The escapement at Campbell Creek was at least 2,376 coho salmon, including 673 fish with an adipose clip (Appendix A). This was a minimum count because the weir was removed before coho salmon finished migrating. High water and excessive debris in the river necessitated the early removal of the weir. A total of 161 heads were collected and shipped to the Tag Lab (Table 3). The escapement count on Ship Creek was 382 fish with 128 of those being adipose clipped. The Ship Creek weir was operated for the entire coho salmon run. A total of 44 heads were recovered and sent to the Tag Lab. Examination of coho salmon for missing adipose fins on other projects yielded 177, 7, and 0 heads from the Little Susitna River, Fish Creek, and Jim Creek, respectively (Table 3). There were 341 coded wire tags decoded from the 389 heads recovered from all weirs. The contribution of hatchery fish to the escapement was calculated from tag recovery data for Campbell and Ship creeks. In Ship Creek, an estimated 202 (53%, SE = 31) of the 382 fish in the escapement were of hatchery origin, 153 (SE = 17) of those were from fish stocked in Ship Creek and 49 (SE = 26) were -13- Table 3. Summary of sampling efforts and escapement counts of coho salmon at weirs in systems in Northern Cook Inlet, 1993. Number Number Number of Number of Number of Total Dates of to Weir Examined Adipose Heads Decodable Passing Operation Clips Collected Tags Weir Ship Creek= 382 382 128 44 35 338 7/29 - 11/3 Campbell Creek 2,376 2,376 673 161 143 2,215 7/29 - 9/16 Little Susitna Rb 34,999 4,860 187 177 156 34,822 7/23 - 9/12 Fish Creek' 2,071 347 8 7 7 2,078 7/08 - 8/20 Jim Creekd 5,532 1,518 0 0 0 5,532 7/16 - 9/12 Totals 996 389 341 a Twenty-eight of the 44 heads collected in Ship Creek were collected during harvest of brood stock. b Bartlett 1994 c The weir at Fish Creek is operated to enumerate sockeye salmon, therefore counts of coho salmon do not represent the entire run (Larry Peltz, Alaska Department of Fish and Game, Palmer, personal communication). d Bartlett Unpublished. from other stocking locations. In Campbell Creek 1,658 of the 2,376 fish (68%) in the escapement were of hatchery origin. Because all coho salmon in the escapement at Campbell Creek were examined for marks and all marked fish recovered were from the Campbell Creek release, no variance was calculated for the contribution of hatchery-produced coho salmon to the escapement. Straying A total of 341 decodable tags were recovered from random samples of the escapements at Ship, Campbell, Jim, and Fish creeks, and the Little Susitna River (Table 4). In Campbell and Fish creeks and the Little Susitna River all of the tags recovered were from fish stocked in that same stream. There was significant straying (P = 0.03, Fisher's exact test) of Campbell Creek fish into Ship Creek. Two of 35 tagged coho salmon recovered in the escapement at Ship Creek were originally released into Campbell Creek. From the escapement of 5,532 coho salmon at Jim Creek a total of 1,518 (27%) fish were examined for missing adipose clips (Bartlett Unpublished). No adipose clipped fish were observed in this sample. In addition, of the 507 tags recovered from the Kenai River sport harvest, one tag was from a coho salmon stocked at Ship Creek (Carlon and Hasbrouck In prep). Returns Total returns of coho salmon to urban area streams are made up of three measurable components: spawning escapement, commercial harvest, and inriver harvest. The spawning escapement and estimates of commercial harvest are presented in this report. Total inriver harvest was estimated through the Statewide Harvest Survey program (Mills 1994). Most of the returns to Ship, Bird, and Campbell creeks were harvested by the sport fishery (Figure 3). Inseason observations of the sport fishery at the Anchorage urban streams indicated that the coho salmon stocking program exceeded expectations. As a new fishery, Campbell Creek supported a large increase in participation, and participation levels at Bird and Ship creeks also appeared to increase. Statewide Harvest Survey estimates (Mills 1994) indicated that effort at Campbell Creek increased from 1,500 angler-days in 1992 to over 9,000 in 1993, and effort at Bird Creek increased by 1,000 angler-days to 12,000 (Figure 4). Harvest estimates indicate that approximately 4,000 coho salmon were harvested at Campbell Creek, and over 6,000 were harvested at Bird Creek. Ship Creek effort did not increase appreciably, but harvest increased by nearly 35% to 2,500 coho salmon. Commercial Harvest of Stocked Coho Salmon A total of 271,118 coho salmon was harvested by the Central District drift net, the Central District eastside set net, and the Northern District set net commercial fisheries in 1993 (Table 5). Catch sampling did not occur over the entire fishing season, and one statistical area in the Northern District, 247- 30, was not sampled. A total of 219,127 coho salmon were harvested during the times and from the statistical areas sampled in 1993 (Table 6). Nearly all of the samples collected from the commercial set net harvest from statistical areas 247-10 and 247-20 were mixed loads from these two areas. Many samples from statistical areas 247-70, 247-80, and 247-90 were also a -15- Table 4. Number of coded wire tagged coho salmon recovered from the escapement by release site in Upper Cook Inlet, 1993. RELEASE SITE RECOVERY SITE= Ship Campbell Little Fish Total Creek Creek Susitna Creek Recoveries Ship Creek 30 30 Campbell Creek 2 143 145 Little Susitna Riverb 1 156 157 Fish Creek 7 7 Homer Spit 2 2 Total 35 143 156 7 341 a No ad-clipped fish were observed in Jim Creek coho escapement (Bartlett Unpublished). b Bartlett 1994. -16- Campbell Creek Little Sus ,j’ tna River Bird Creek Ship Creek Commercial ’ 1 Sport 284 0 Escapement314 L ’ Estimate of hatchery contribution to the UCI coho salmon commercial harvest from catch sampling data. 2Estimate of sport harvest of coho salmon from SHS (estimates of hatchery contribution not calculated). 3 Estimate of hatchery contribution to the escapement (Bird Creek is a minimum estimate of the total escapement from a foot survey). 4Little Susitna estimates for hatchery contribution to sport harvest and escapement from Bartlett (Unpublished). Figure 3. Distribution of coho salmon returns among commercial and sport fisheries and the escapement in three stocked streams. -17- 70,000 1, Fishing Effort Increase of 9,400 60,000 3 6 50,000 6 40,000 : ; 30,000 % 20,000 Five Year Mean 10,000 n u 1988 1989 1990 1991 1992 1993 Coho Salmon Harvest ‘b 14,000 [ I Increase Harvest of 10,200 Fish I z Five Year Mean f 4,000 s 2,000 u 1988 1989 1990 1991 1992 1993 Figure 4. Sport harvest and effort streams (Campbell, Ship salmon (Mills 1989-1994). from 1988 to 1993 in Anchorage urban and Bird creeks) stocked with coho -18- Table 5. Total harvest of coho salmon in commercial fisheries of Upper Cook Inlet in 1993 except for set net fisheries in statistical areas 245 and 246. Statistical Dates Dates Ge= Area Benin End 6/25-7/11 Drift net 244 h 24Sa 6/25 9/03 1,300 23,119 49,548 40,379 Set net 244-21 22 30 40 Total 247-lo-20b 30 41 42 43 50 70-80-90= Total Grand Total 271,118 7/02 8/13 7/02 8/13 7/05 8/13 7/05 8/13 7/05 8/30 7/02 8/16 7/16 8/16 7/12 8/16 7/02 9/13 7/18 7/25 7/02 9/13 23 218 270 1,109 11 465 620 1,512 9 816 3,063 6,857 12 1.573 5.821 L!zklx 55 3,072 9,774 19,914 117 40 557 111 724 7/12-7/21 - 7/22-7/28 7/29-8/04 8/05-8/11 8/12-8/18 8/19-9115 Total 4,343 3,902 7,898 8,276 357 961 176 196 474 1,199 175 656 494 1.225 13,917 16,415 - a Combination of statistical areas 244-50, 244-60, 244-70, 245-70, 245-80, and 245-90. b Combination of statistical areas 247-10 and 247-20. 6,565 18,635 4,196 2,912 2,623 1.710 36,641 4,878 1,382 1,305 828 1,765 759 1,967 608 2.190 7,227 3,033 4,206 3,564 4,278 434 2,018 473 1,838 795 2,820 1,606 2.091 4.207 17,251 11,079 1,179 121,785 3,753 5,132 13,320 iLQLtEQ 43,075 1 900 L5!Lxa 10,231 22,698 39,561 8,005 5,917 10,179 831 19.067 106,258 ’ Combination of statistical areas 247-70, 247-80, and 247-90. Table 6. Harvest of coho salmon from sampled commercial fisheries of Upper Cook Inlet in 1993. Gear Statistical Dates Dates area Begin End 7/12-7/21 7/22-7/28 7/29-8/04 8/05-8/11 8/12-8/18 8/19-9/15 Total Drift net 244 6 24Sa 7/12 8/09 23.119 49,548 40,379 4,878 117,924 8/13 8/13 8/13 8/13 270 1,109 1,305 828 3,512 620 1,512 1,765 759 4,656 2,830 6,857 1,967 608 12,262 5.439 10.436 2.190 _838 lt?s!Q3 9,159 19,914 7,227 3,033 39,333 Set net 244-21 7/23 22 7/23 30 7/23 40 7/23 Total 247-lo-20b 7/19 30= 41 7/16 42 7/16 43 7/16 50 7/18 70-80-90d 7/16 Total 20,059 0 8,005 5,787 159 8,874 101 9.330 19.044 9,489 61,870 8/16 1,822 3,902 6,565 4,206 3,564 357 174 467 101 481 3,402 8/16 8/13 8/20 7/18 9/13 961 4,196 2,018 473 196 2,912 1,838 667 1,199 2,623 2,820 1,606 1.225 1.710 2.091 4,207 7,483 18,006 12,973 10,517 Grand Total 219,127 a Combination of statistical areas 244-50, 244-60, 244-70, 245-70, 245-80, and 245-90. b Combination of statistical areas 247-10 and 247-20. c No coho salmon sampled from those harvested in statistical area 247-30. d Combination of statistical areas 247-70, 247-80, and 247-90. mixture from these three statistical areas. Other samples that were recorded as pure loads from one of the three statistical areas were also likely a mixture of fish harvested from the three statistical areas. Therefore, samples and harvest data from 247-10 and 247-20 were pooled together and those from 247-70, 247-80, and 247-90 were pooled together. Statistical areas from the Central District eastside set net fishery were not pooled because precision of the estimates did not improve appreciably when the areas were combined. Likewise, pooling data into weeks did not generally improve preci- sion, especially in the Central District fisheries. Therefore, estimates of harvest of marked groups were stratified by statistical area, except those when the data were pooled because samples represented a mixture of fish harvested from different statistical areas, and by date. The majority of the UC1 coho harvest was taken in the Central District drift net fishery, followed by the Northern District set net fishery (Figure 5). Similarly, most of the hatchery-produced coho salmon were recovered in the Central District drift net and Northern District set net fisheries (Table 7, Figure 5). Overall, hatchery stocked coho salmon contributed 7.7% to the UC1 coho salmon harvest sampled (Figure 6). When estimated by fishery, 7.6% of the sampled harvest of the Central District drift net fishery, 4.5% of the Central District set net fishery, and 10% of the Northern District set net fishery was composed of hatchery-produced fish (Figures 7, 8, and 9, respec- tively). The largest contributors to the commercial harvest were coho salmon stocked in three streams in the Anchorage urban area (Bird, Campbell, and Ship creeks) and the 1992 smolt releases into the Little Susitna River. The returns to the Little Susitna River composed over 50% of the hatchery returns in all of the fisheries. Coho salmon stocked into Bird and Campbell creeks provided nearly equal numbers of fish to each fishery. Relatively few coho salmon stocked into Ship Creek were harvested by the set net fisheries and no tags were recovered from the drift net fishery. Coho salmon from Ship Creek appeared later in the harvest than those stocked into Bird and Campbell creeks. Fish released into Ship Creek were from a different brood stock and may have a later run timing than those stocked into Bird and Campbell creeks. DISCUSSION Sport Fishery The measure of success of the coho salmon stocking program is an increase in angler effort and harvest. The targeted increase in harvest of 10,000 fish was achieved, with a 10,020 fish increase over 1992 and a 10,200 fish increase over the 5-year mean. The estimated harvest is species specific so this increase is easily quantified. The ultimate measure of success, however, is the increase in angler effort. The Statewide Harvest Survey estimates angling effort for all species combined. Increased angler effort for a specific species is not easily quantified and may be masked or exaggerated by fluctua- tions in effort of other fisheries. The targeted increase in angler effort of 20,000 angler-days was achieved when compared to the 5-year mean, but there was only a 9,400 angler-day increase over the previous year. The true increase in angler effort for coho salmon may be masked by the continually increasing popularity of the chinook salmon fishery in Ship Creek. This fishery has grown dramatically in recent years and is included in the estimate of angler effort. In addition, a weakness of using the Statewide Harvest -21- 53.8% Distribution of Harvest Sampled Among Three UCI Fisheries 17 52.8% ,2% Distribution of Hatchery Contribution Among Three UCI Fisheries “-‘% urn,, 0 CDD El CDS I Figure 5. Distribution of coho salmon harvest and hatchery contribution among three UC1 fisheries, Central District drift net (CDD), Central District set net (CDS), and Northern District set net (NDS), 1993. -22- Table 7. Estimates of harvest (nl> and variance [V(nl)] by release site of stocked coho salmon in the commercial fishery in Upper Cook Inlet, 1993. Release Site Gear Dates Statistical 7/12-7/21 7/22-7/28 7/29-8/04 8/05-8/11 8/12-8/18 8/19-9/15 Total area nl V(n1) nl V(n1) Ill VW) nl VW) nl V(n1) nl V(n1) nl VW) Bird Creek Drift net 244 & 245 (1992 smelt) Set Net 244-21 22 30 40 247-10-20 41 42 43 70-80-90 Campbell Creek Drift net 244 5. 245 (1992 smol t) Set Net 244-2 1 22 30 40 247-10-20 41 42 43 70-80-90 Ship Creek Set Net 244-30 (1992 smolt) 247-10-20 43 70-80-90 Cottonwood Creek Drift net 244 6 245 (1992 smol t) Set Net 247- 41 42 43 70-80-90 Fish Creek Drift net 244 & 245 (1992 smelt,) Set Net 247- 41 42 43 70-80-90 183 1,169 633 5,629 10 83 74 722 6 28 21 204 4 15 39 86 4 11 11 108 120 804 748 6,349 19 156 28 132 5 8 8 63 10 97 7 27 44 94 687 5,018 49 8 41 14 80 176 2,531 7 26 159 16 24 125 23 40 151 32 56 154 84 110 710 122 633 4,278 68 15 8 56 41 295 173 1,924 29 44 242 73 84 387 33 80 274 68 169 701 120 82 529 48 12 2 4 2 7 44 4 11 32 2 3 3 11 48 6 8 4 2 2 4 2 3 558 54 518 20 155 249 140 230 3,043 891 102 94 704 325 265 283 1,011 124 3 10 5 11 5 4 13 106 114 14 32 8 26 16 37 31 87 121 185 79 so9 9 17 3 3 6 6 2 3 2 3 3 3 5 2 6 10 60 171 8 14 30 76 141 128 2 1 1,552 12,374 8 54 41 518 24 163 257 3,273 46 328 87 638 72 291 295 668 421 4,709 1,569 12,322 15 102 8 56 60 451 230 2,150 133 1,035 143 846 184 633 470 1,304 239 2,125 12 9 5 149 7 2 4 11 7 11 2 13 9 2 124 17 6 138 44 3 10 32 9 48 3 24 9 3 -continued- Table 7. (Page 2 of 3). Dates Statistical 7/12-7/21 7/22-7/28 7/29-8/04 8/05-8/11 8/12-8/18 8/19-9/E Total Release Site Gear area nl V(n1) n1 V(n1) nl v(nl) nl VW) nl V(n1) nl V(n1) nl VW) Meadow Creek Set net (1990 f ingerl ing) Was i 11 a Creek (1992 smol t) Hous ton (1992 molt) Nancy Lake (1992 smelt) Drift net Set Net 244 6 245 8 55 244-40 247- 41 42 43 70-80-90 Drift net Set net 244 & 245 136 3,625 833 24,304 973 23,272 63 3,857 244-21 22 30 40 247-10-20 41 42 43 50 70-80-90 Drift net 244 & 245 Set net 244-22 30 40 244-40 64 4,032 64 4,032 247-42 43 70-80-90 82 3,274 89 2,052 20 375 12 57 16 113 19 58 4 4 9 70 3 8 5 8 10 2 14 2 3 5 82 3,274 89 2,052 20 375 29 182 16 113 19 58 3 8 19 26 5 7 2,005 55,058 105 1,787 81 2,092 33 1,059 70 633 21 417 34 1,112 24 559 22 455 44 912 87 2,642 72 1,313 140 2,320 191 2,474 79 1,148 11 110 1,484 37,076 142 4,664 173 5,811 143 2,136 113 1,064 27 11 50 78 9 326 103 566 634 74 9 65 465 11,151 1,149 36,153 96 2,967 58 1,798 81 3,166 24 559 22 455 44 912 192 4,429 322 8,395 357 9,293 384 5,176 340 3,479 21 417 63 1,361 3,179 87,546 50 1,195 50 2,446 100 3,641 68 1,461 55 2,981 219 7,409 262 7,605 55 947 375 10,350 247-10-20 41 42 43 70-80-90 17 262 57 1,540 32 477 104 3,480 105 1,001 36 1,226 69 1,630 176 5,478 150 2,657 143 5,015 251 3,377 67 1,079 134 2,866 135 1,403 12 122 28 357 34 341 13 159 48 462 92 2,157 25 290 319 8,910 463 11,970 331 4,615 422 5,732 193 4,152 -continued- Table 7. (Page 3 of 3). Dates Statistical 7/12-7/21 7/22-7/28 7/29-8/04 8/05-8/11 8/12-8/18 8/19-9/E Total Release Site Gear area nl V(n1) nl V(n1) nl VW) nl VW) nl VW) nl V(n1) nl VW) Nancy Lakea Drift net ( 1990 f ingerl ing) Set net Nancy Lak$ Drift net (1990 f ingerl ing) Set net Nancy Lake= Drift net (1991 molt) 244 & 245 290 27 699 83 1,644 244-40 18 290 20 365 18 36 694 36 LoA VI7 247-10-20 18 41 36 42 13 43 7 43 70-80-90 8 302 413 154 52 244 & 245 70 1,556 174 4,990 223 18 304 18 5,294 467 11,840 244-40 294 247-41 49 763 42 28 402 43 17 126 70-80-90 11 108 244 & 245 20 373 45 962 7 41 42 416 23 150 6 25 6 34 32 978 49 772 12 142 10 85 18 302 88 1,416 55 570 6 32 42 250 14 86 36 598 81 1,741 89 1,316 27 211 11 108 20 373 Little Susitna River Total d 617 15,932 2,654 77,365 4,123 93,194 1,529 42,191 362 4,822 34 274 9,375 233,269 Grand Total 1,089 19,839 4,535 96,889 7,106 124,437 2,712 58,143 1,014 8,900 310 1,167 16,885 308,737 Fingerling released into Nancy Lake in 1990 with tag code 1301010405. Fingerling released into Nancy Lake in 1990 with tag code 1301010406. Smolt released into Nancy Lake in 1991. Total for Little Susitna includes only the 1992 smolt releases. UPPER COOK INLET COHO SALMON FISHERY Portion of Harvest Represented by Sample ‘““d~“n,~b~~p’e by Stocking Stocking Contribution by Release Site Bird Creek Campbell Creek Shi Creek Litt e Susitna River P mother NCI hatchery releases Figure 6. Portion of Upper Cook Inlet coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample. -26- I CENTRAL DISTRICT DRIFT FISHERY Portion of Harvest Represented by Sample Stocking Contribution by Release Site 58.1% Figure 7. Portion of Central District drift, coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample. -27- CENTRAL DISTRICT SET NET FISHERY w Portion of Harvest Represented by Sample Portion of Sample Contributed by Stocking 18.5% Stocking Contribution 8.5% by Release Site Figure 8. Portion of Central District set net coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample. -28- I ERN DISTRICT SET NET FISHERY Portion of Harvest Represented by Sample Portion of Sample Contributed by Stocking Stocking Contribution 11.5% by Release Site 52.0% Bird Creek Campbell Creek Shi Creek Litt e Susitna River P Other NCI hatchery releases Figure 9. Portion of Northern District set net, coho salmon commercial harvest represented by 1993 sampling efforts, and contribution of hatchery fish to that sample. -29- Survey is that the survey targets licensed anglers. Urban creeks, especially Campbell Creek, are fished primarily by young anglers who are not required to purchase a license. Thus, these estimates of harvest and effort are consid- ered minimal estimates. We believe results presented in this report and field observations of the sport fisheries indicate that the urban coho salmon stocking program succeeded in 1993. Fish movements and best times for angling were different among the systems. At Campbell Creek, fish stayed in Campbell Lake during low water and moved into the fishery when water level increased after heavy rainfalls. The fish- eries in Bird and Ship creeks, being essentially intertidal, were more closely related to the tides. Greatest success was during the 2 to 3 hours before and after high tides. This information should be considered in designing future sport sampling schedules. Escapement The biological escapement goal (BEG) of 200 coho salmon was met on both Ship and Campbell creeks. Although no coho salmon were observed jumping over the dam at Ship Creek during the highest tides at either day or night time, this concern still exists because hatchery staff have seen chinook salmon jump over the dam. In addition, hatchery staff have observed chinook salmon passing through the flow control gates of the dam when they are open. Since coho salmon may act similarly, this escapement count is considered a minimum rather than a total count. The escapement count at Campbell Creek is also considered a minimum because the weir was removed before all coho salmon passed the weir. This minimum escapement count exceeded the BEG by a factor of ten, indicating that returns from this stocking effort were more than adequate for supporting the fishery. Straying The straying of hatchery-reared coho salmon was tested because of concerns that hatchery fish may compete with wild stocks for spawning areas, and the potential of genetic changes from mixing of wild and stocked fish. Our results indicate that straying is not a major concern. No straying occurred in any of the systems except Ship Creek. The trap box at Ship Creek is located at the upper extent of the intertidal area. Salmon stay or mill in the mouths of non-natal systems (Sandercock 19911, thus the Campbell Creek fish captured in Ship Creek may not have been destined to enter Ship Creek to spawn. Tag Loss Tag loss was detected by the absence of coded wire tags in adipose clipped fish. Tag loss estimated from the escapement samples ranged from 12% to 26% while tag loss in these same groups ranged between lo%-17% at release (Peltz and Starkey 1993). Therefore, tag loss occurred primarily before the fish were released and tag loss after release was relatively low. -3o- Commercial Catch Assessment Catch sampling of the UC1 coho salmon fishery in 1993 was conducted when 81% of the coho salmon harvest occurred. Technicians examined 38% of this harvest and nearly 3% of the fish examined had adipose clips. Estimates of the contribution of hatchery-produced fish to the UC1 commercial fisheries indicated that nearly 8% of the harvest sampled was of hatchery origin. The pattern of the commercial harvest was typical of previous years. Forty- five percent of the coho salmon harvest occurred in the Central District drift net fishery, 16% in the Central District eastside set net fishery, and 39% in the Northern District set net fishery. The majority of the hatchery stocked fish harvested by the UC1 commercial fishery were taken in the Central District drift net fishery: 52% of the total commercial harvest of coho salmon stocked into Anchorage urban systems and 55% of the total commercial harvest of coho salmon stocked into the Little Susitna River. The Northern District set net fishery took 37% of the estimated total commercial harvest of coho salmon stocked into Anchorage urban systems and 34% of the estimated total commercial harvest of coho salmon stocked into the Little Susitna River. The Central District eastside set net fishery took only 11% of the total commercial harvest of coho salmon stocked into both the Anchorage urban systems and the Little Susitna River. Some results from the estimates of the commercial harvest of hatchery-produced coho salmon should be noted. First, pooling data among statistical areas or days generally did not improve precision of the estimates of the Central District fisheries. In addition, incorporating covariance terms when summing estimated variances among release groups within strata did not reduce the variance estimates greatly. Estimates of harvest of marked cohorts within the statistical area/day strata are not independent, so the total variance esti- mate has an additional covariance component (Clark and Bernard 1987). The small reduction in total variance resulting from incorporation of the covari- antes terms occurred because the catch sampling program recovers a large number of tagged fish from each cohort and the Tag Lab loses few heads due to good quality control. Our results justify continuation of the stocking program. The terminal and commercial assessment programs should continue to evaluate the stocking program and determine if the success of this first year continues. Recom- mendations for the future include better sampling of several statistical areas in the Northern District (i.e., 247-10, 247-20, 247-30, 247-70, 247-80, and 247-90). This could be accomplished by placing technicians aboard tenders more frequently, closely following buying patterns of processors inseason, maintaining good rapport with processors, and stationing technicians in Homer and Soldotna. These steps would improve our ability to sample pure loads of coho salmon harvested in these statistical areas. The escapement count at Campbell Creek could be improved by using a floating weir rather than the picket weir used in 1993. A floating weir should perform better with high water and associated debris loads which occur during August and September. -31- ACKNOWLEDGMENTS The data presented here result from the efforts of many individuals. Paul Cyr served as the project leader's right-hand man, which involved coordinating the efforts of all phases of the program while conducting other necessary area management activities. Terry Bradley coordinated the weir installation, operations and scheduling. Dan Bosch coordinated the commercial catch sampling. Mike Seine, Matt Miller, Joey Caterinichio, Paul, Terry, and Dan all conducted the commercial and sport catch sampling and daily weir operations. The crew at the Elmendorf Hatchery assisted by monitoring the live-box at the Ship Creek fish pass. Dave Waltemyer, Kim Rudge, and Jay Carlon supervised a host of technicians from the Soldotna ADF&G office who collected data from the Central District. Kim's daily updates were greatly appreciated. Anna Sharp, Sam Bertoni, Karen Crandall, and the rest of the staff at the Tag Lab in Juneau were always helpful and very patient in helping us come up to speed in dealing with coded wire tag data. Doug McBride, Kelly Hepler, and Doug Vincent-Lang offered inseason technical assistance and moral support as well as postseason motivation for project completion. LITERATURE CITED Bartlett, L. D. 1994. Creel, escapement, and stock statistics for coho salmon on the Little Susitna River, Alaska, during 1993. Alaska Department of Fish and Game, Fishery Data Series No. 94-29, Anchorage. . Unpublished. Coho and sockeye salmon stock assessment studies in the Jim Creek drainage, Knik Arm, Alaska, during 1993. Alaska Department of Fish and Game, Division of Sport Fish, Palmer. Carlon, J. 1992. Feasibility of capturing and marking juvenile coho salmon for stock assessment in the Kenai River. Alaska Department of Fish and Game, Fishery Data Series No. 92-57, Anchorage. Carlon, J. and J. J. Hasbrouck. In prep. Recovery and estimation of commercial harvest of coho salmon from the Kenai River in the Upper Cook Inlet fishery in 1993. Alaska Department of Fish and Game, Fishery Data Series, Anchorage. Clark, J. E. and D. R. Bernard. 1987. A compound multivariate binomial- hypergeometric distribution describing coded microwire tag recovery from commercial salmon catches in Southeastern Alaska. Alaska Department of Fish and Game, Division of Commercial Fisheries, Informational Leaflet No. 261. Juneau. Meyer, S., D. V. Vincent-Lang, and D. McBride. Unpublished. Goal statement and study plan for the development of a stock assessment program for Upper Cook Inlet coho salmon stocks (1991). Alaska Department of Fish and Game, Division of Sport Fish, Anchorage. Mills, M. J. 1979. Alaska statewide sport fish harvest studies. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1978-1979, Project F-9-11, 20 (SW-I-A), Juneau. -32- LITERATURE CITED (Continued) . 1980. Alaska statewide sport fish harvest studies. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1979-1980, Project F-9-12, 21 (SW-I-A), Juneau. -* 1981a. Alaska statewide sport fish harvest studies 1979 data. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1980-1981, Project F-9-13, 22 (SW-I-A), Juneau. . 1981b. Alaska statewide sport fish harvest studies 1980 data. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1980-1981, Project F-9-13, 22 (SW-I-A) Juneau. . 1982. Alaska statewide sport fish harvest studies 1981 data. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1981-1982, Project F-9-14, 23 (SW-I-A), Juneau. -* 1983. Alaska statewide sport fish harvest studies 1982 data. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1982-1983, Project F-9-15, 24 (SW-I-A), Juneau. -* 1984. Alaska statewide sport fish harvest studies 1983 data. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1983-1984, Project F-9-16, 25 (SW-I-A), Juneau. . 1985. Alaska statewide sport fish harvest studies 1984 data. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1984-1985, Project F-9-17, 26 (SW-I-A), Juneau. . 1986. Alaska statewide sport fish harvest studies 1985 data. Alaska Department of Fish and Game. Federal Aid in Fish Restoration, Annual Performance Report, 1985-1986, Project F-10-1, 27 CRT-21, Juneau. -* 1987. Alaska statewide sport fisheries harvest report 1986. Alaska Department of Fish and Game, Fishery Data Series No. 2, Juneau. -* 1988. Alaska statewide sport fisheries harvest report 1987. Alaska Department of Fish and Game, Fishery Data Series No. 52, Juneau. . 1989. Alaska statewide sport fisheries harvest report 1988. Alaska Department of Fish and Game, Fishery Data Series No. 122, Juneau. 1990. i989. Harvest and participation in Alaska sport fisheries during Alaska Department of Fish and Game, Fishery Data Series No. 90- 44, Anchorage. -- 1991. Harvest, catch, and participation in Alaska sport fisheries during 1990. Alaska Department of Fish and Game, Fishery Data Series No. 91-58, Anchorage. -33- LITERATURE CITED (Continued) 1992. Harvest, catch, and participation in Alaska sport fisheries during 1991. Alaska Department of Fish and Game, Fishery Data Series No. 92-40, Anchorage. . 1993. Harvest, catch, and participation in Alaska sport fisheries during 1992. Alaska Department of Fish and Game, Fishery Data Series No. 93-42, Anchorage. . 1994. Harvest, catch, and participation in Alaska sport fisheries during 1993. Alaska Department of Fish and Game, Fishery Data Series No. 94-28, Anchorage. Sandercock, F. K. 1991. Life history of coho salmon (Oncorhynchus kisutch). In C. Groot and L. Margolis, editors. Pacific salmon life histories. UBC Press. Vancouver, B.C., Canada. Peltz, L. and D. Starkey. 1993. Summary and synthesis of production, marking, and release data for coho and chinook salmon smolt releases into Upper Cook Inlet, Alaska, in 1992. Alaska Department of Fish and Game, Fishery Data Series No. 93-51. Anchorage. -34- APPENDIX A -35- Appendix A. Daily escapement counts of coho salmon from weirs on Campbell and Ship creeks, 1993. DATE Campbell Creek Ship Creek Total Coho Adinose Cl- Total Coho Adinose Clins July 19 30 31 August 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 September 1 2 3 4 5 6 7 8 9 10 11 12 weir installed 2 3 1 39 10 19 4 16 4 91 19 9 3 4 2 98 331 186 424 76 22 50 134 41 98 33 51 94 12 142 1 23 93 42 167 18 3 12 36 6 31 9 11 25 3 33 3 2 4 3 6 15 27 22 22 7 9 1 4 14 6 3 2 2 1 2 3 8 7 11 5 3 3 16 1 44 5 3 12 2 1 1 2 8 18 2 2 11 2 13 174 52 5 3 -continued- -36- Appendix A. (Page 2 of 2). DATE Campbell Creek Ship Creek 14 160 48 3 1 15 63 20 16 weir removed 18 6 17 13 6 18 3 3 19 20 21 3 3 22 2 2 23 2 1 24 25 1 26 27 28 29 2 30 5 October 1 2 4 3 2 4 5 6 7 8 9 10 11 1 12 1 13 14 15 5 16 17 ii 2 20 21 3 22 23 24 25 26 27 2 28 29 2 30 31 November 1 4 2 TOTAL 2.376 673 389 128 1 1 1 -37- TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF APPENDICES ABSTRACT INTRODUCTION OBJECTIVES METHODS RESULTS DISCUSSION ACKNOWLEDGMENTS LITERATURE CITED APPENDIX A
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