NOAA Technical Memorandum NMFS-AFSC-18


Adult Sockeye and Pink Salmon Tagging 

Experiments for Separating Stocks in 

Northern British Columbia and Southern 

Southeast Alaska, 1982-1985 

by 

Jerome Pella, Margaret Hoffman, Stephen Hoffman, Michele Masuda, 

Sam Nelson, and Larry Talley 

U.S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration


National Marine Fisheries Service


Alaska Fisheries Science Center


August 1993 
NOAA Technical Memorandum NMFS

The National Marine Fisheries Service's Alaska Fisheries Science Center

uses the NOAA Technical Memorandum series to issue informal scientific and

technical publications when complete formal review and editorial processing

are not appropriate or feasible. Documents within this series reflect sound

professional work and may be referenced in the formal scientific and technical

literature.

The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries

Science Center continues the NMFS-F/NWC series established in 1970 by the

Northwest Fisheries Center. The NMFS-NWFSC series will be used by the

Northwest Fisheries Science Center.

This document should be cited as follows:

Pella, J., M. Hoffman, S. Hoffman, M. Masuda, S. Nelson, and L. Talley 

1993. Adult sockeye and pink salmon tagging experiments for

separating stocks in northern British Columbia and southern Southeast

Alaska, 1982-1985 U.S. Dep. Commer., NOAA Tech. Memo. NMFSAFSC-18, 134 p.

Reference in this document to trade names does not imply endorsement by

the National Marine Fisheries Service, NOAA.
NOAA Technical Memorandum NMFS-AFSC-18

Adult Sockeye and Pink Salmon Tagging

Experiments for Separating Stocks in

Northern British Columbia and Southern

Southeast Alaska, 1982-1985

bY

Jerome Pella’, Margaret Hoffman’, Stephen Hoffman:

Michele Masuda’, Sam Nelson’, and Larry Talley’

‘Auke Bay Laboratory

Alaska Fisheries Science Center

11305 Glacier Highway

Juneau AK 99801-8626

‘Alaska Department of Fish and Game

Region 1

P.O. Box 240020

Douglas AK 99824-0020

U.S. DEPARTMENT OF COMMERCE

Ronald H. Brown, Secretary

National Oceanic and Atmospheric Administration

Diana Josephson, Acting Administrator

August 1993
This document is available to the public through:

National Technical Information Service

U.S. Department of Commerce

5285 Port Royal Road

Springfield, VA 22161
Notice to Users of this Document 

This document is being made available in .PDF format for the convenience of users; however, the 

accuracy and correctness of the document can only be certified as was presented in the original hard 

copy format. 

iii

ABSTRACT

Adult sockeye (Oncorhynchus nerka) and pink

(0. gorbuscha) salmon were-captured, tagged, and released in

coastal fisheries of southern Southeast Alaska and northern

British Columbia between 1982 and 1985. Sockeye salmon were

tagged in 1982 and 1983; pink salmon were tagged in 1982,

1984, and 1985. The tagging experiments were part of a cooperative effort by the United States and Canada to assess

contributions of stocks of each country to fisheries of the

region and to learn about the coastal migrations of these

salmon.

Catches and escapements in Alaska and Canada were sampled

for the purpose of estimating numbers of tagged fish that

either were caught among or escaped to contributing stocks.

Estimated numbers of tagged fish in catches and escapements

were used to assess stock composition of catches of the fisheries during the tagging years.

Most sockeye salmon in Alaskan fisheries were of Canadian

origin, and only a small percentage of the catch in Canada was

of Alaskan origin. Alaskan sockeye salmon were relatively

more numerous in 1982 than in 1983, compared to Canadian

stocks of those years. Sockeye salmon from the Canadian Nass

and Skeena Rivers constituted major portions of catches of

most fisheries. In 1983, southward-migrating stocks, probably

mainly from Canada's Fraser River, occurred in outer coastal

fisheries of Alaska and Canada, and in Canadian fisheries at

the southern end of the study area..

Most pink salmon in nearly all Alaskan fisheries

throughout the season were of Alaskan origin. Only in two of

nine Alaskan fishing areas examined did the percentage from

Alaskan stocks drop below 75% at times. Percentage of Alaskan

pink salmon in Canadian fisheries was also substantial but

more variable among areas and years of tagging than in Alaska.

In Canada, percentage of Alaskan pink salmon was generally

greatest in areas adjoining Alaska.

The interpretation of the experiments for assessing stock

composition in fisheries was fraught with difficulties. Among

the shortcomings were large potential errors in estimates of

numbers of tagged fish escaping to the spawning grounds. How-

'ever, numerical studies showed that stock-composition estimates for sockeye or pink salmon would generally not be

misleading because of such errors. Lack of information on

stock origin of tagged fish caught in intervening fisheries

and the apparent incomplete accounting for tagged fish in

sampled catches and escapements were further deficiencies

whose potential effects on stock-composition estimates were

not examined.

V

CONTENTS

LIST OF TABLES ....................

LIST OF FIGURES. ...................

INTRODUCTION .....................

METHODS ........................

ASSUMPTIONS, DATA ANALYSIS, AND LIMITATIONS ...... Assumptions ................... Data Analysis ..................

SOCKEYE SALMON TAGGING EXPERIMENTS OF 1982 AND 1983 . .

Primary Tagging in the Fisheries ......... Fishery Recoveries................ Terminal Recoveries

Stock-Composition Estimate ................. s .

....... Discussion .................... Sensitivity Analysis ...............

PINK SALMON TAGGING EXPERIMENTS OF 1982, 1984, AND 1985

Primary Tagging in the Fisheries .

Fishery Recoveries . . . . . . . . .

Terminal Recoveries . . . . . . . .

Stock-Composition Estimates . . . .

Discussion . . . . . . . . . . . . .

Sensitivity Analysis . . . . . . .

DISCUSSION AND SUMMARY . . . . . . . . .

Primary Tagging . . . . . . . . . .

Fishery Recoveries . . . . . . . . .

Terminal Recoveries . . . . . . . .

Sockeye salmon . . . . . . . .

Pink salmon. . . . . . . . . .

Stock-Composition Estimation Method

Stock-Composition Estimates . . . .

Sockeye salmon . . . . . Sensitivity analysis . . .

Pink salmon . . . . . . . . . .

Sensitivity analysis . . .

Caveats and Qualifications . . . . .

ACKNOWLEDGMENTS. . . . . . . . . . . . .

CITATIONS . . . . . . . . . . . . . . . .

TABLES . . . . . . . . . . . . . . . . .

FIGURES.................

GLOSSARY . . . . . . . . . . . . . . . .

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vii

LIST OF TABLES

Table 1. --Delineation of general areas of release in

Southeast Alaska in terms of the Alaska

Department of Fish and Game statistical

system..................... 53

Table 2. --Delineation of general areas of release in

British Columbia in terms of the Canada

Department of Fisheries and Oceans

statistical system. . . . . . . . . . . . . . . 54

Table 3. --Delineation of areas of release in

Canada's Dixon Entrance in terms of Canada

Department of Fisheries and Oceans

statistical system by year: 1984 and

1985...................... 54

Table 4. --Number of tagged sockeye salmon released

in southern Southeast Alaska and northern

British Columbia, 1982 and 1983. . . . . . . . 55

Table 5. --Estimates of total numbers of tagged

sockeye salmon caught in Alaskan and

Canadian fisheries by general area and

period of release, 1982. . . . . . . . . . . . 56

Table 6. --Estimates of total numbers* of tagged

sockeye salmon caught in Alaskan and

Canadian fisheries by general area and

period of release, 1983. . . . . . . . . . . . 57

Table 7. --Southeast Alaskan sockeye salmon

escapement and weir counts by fishing

district, 1982 and 1983. . . . . . . . . . . . 58

Table 8. --Numbers of sockeye salmon released in

secondary tagging on the Skeena, Nass, and

Stikine Rivers (adjusted for straying),

numbers recovered at weirs or during footsurveys of spawning grounds (Nass and

Skeena Rivers) or in the commercial river

fishery (Stikine River), and the recovery

rate of tagged fish in each river, 1982

and 1983 (Source: Gazey et al. 1983;

English et al. 1984). . . . . . . . . . . . . . 59

Table 9. --Estimates of total numbers of tagged

sockeye salmon escaping to Alaskan and

Canadian spawning areas by period and

general area of release, 1982. . . . . . . . . 60

Table 10. --Estimates of total numbers of tagged

sockeye salmon escaping to Alaskan and

Canadian spawning areas by period and

general area of release, 1983. . . . . . . . . 61

Table 11. --Numbers of tagged sockeye salmon

released, combined numbers estimated as
viii

caught or escaping, percentage of total

estimated recoveries from catch and

escapement, and recovery rate of tagged

releases estimated as occurring in catch

or escapement, by release fishery and

year. . . . . . . . . . . . . . . . . .

Table 12. --1982 stock-composition estimates (%) of

sockeye salmon by area and period of

release, totals for Alaska and Canada

(%), and estimated numbers of tagged

fish in Alaskan and Canadian escapements

Best estimates of escapements were

used, and recovery rate of primarytagged entrants to major rivers in

Canada was assumed to equal that of

secondary-tagged fish. . . . . . . . . .

Table 13. --1983 stock-composition estimates (%) of

sockeye salmon by area and period of

release, totals for Alaska and Canada

(%), and estimated numbers of tagged

fish in Alaskan and Canadian escapements

Best estimates of escapements were

used, and recovery rate of primarytagged entrants to major rivers in

Canada was assumed equal to that of

secondary-tagged fish. . . . . . . . . .

Table 14. --Percentage of Alaskan-origin* sockeye

salmon (bootstrap standard error in

parentheses) by fishery and period of

release, 1982. Dash means no estimate

could be made. . . . . . . . . . . . . .

Table 15. --Percentage of Alaskan-origin* sockeye

salmon (bootstrap standard error in

parentheses) by fishery and period of

release, 1983. Dash means no estimate

could be made. . . . . . . . . . . . . .

Table 16. --Number of tags recovered in catches and

escapements of sockeye salmon by area

and period of release in 1982. . . . . .

Table 17. --Number of tags recovered in catches and

escapements of sockeye salmon by area

and period of release in 1983. . . . . .

Table 18. --Percentages of Alaskan-origin sockeye

salmon by area and period of release for

which 10 or more tags were recovered in

catch and escapement sampling, 1982 and

1983. . . . . . . . . . . . . . . . . .

Table 19.--Estimated season stock compositions

based on catch-weighted averages" of

half-month percentage of sockeye salmon

. . . 62

. . . 63

. . . 65

. . . 67

. . . 68

. . . 69

. . . 70

. . . 71
ix

. . . 72

. . . 73

. . . 74

. . . 75

. . . 76

in northern boundary fisheries bound for

the other country, -1982 and 1983. . . .

Table 20. --Effects of different estimates of

Alaskan escapements and Canadian

secondary-tagging mortality on estimated

season percentages of Canadian sockeye

salmon in Alaskan fisheries, 1982 and

1983. . . . . . . . . . . . . . . . . .

Table 21.--Effects of different estimates of

Alaskan escapements and Canadian

secondary-tagging mortality on estimated

season percentages of Alaskan sockeye

salmon in Canadian fisheries, 1982 and

1983. . . . . . . . . . . . . . . . . .

Table 22. --Number of tagged pink salmon released in

southern Southeast Alaska and northern

British Columbia, 1982, 1984, and 1985.

Table 23. --Estimates of total* tagged pink salmon

caught in Alaskan and Canadian fisheries

by general area and period of release in

1982. . . . . . . . . . . . . . . . . .

Table 24. --Estimates of totale

 tagged pink salmon

caught in Alaskan and Canadian fisheries

by general area and period of release in

1984. . . . . . . . . . . . . . . . . .

Table 25. --Estimates of total* tagged pink salmon

caught in Alaskan and Canadian fisheries

by general area and period of release in

1985. . . . . . . . . . . . . . . . . .

Table 26. --Southeast Alaska pink salmon escapement

estimates and numbers of carcasses

examined for tags by ADF&G statistical

areas, 1982, 1984, and 1985. . . . . . .

Table 27. --British Columbia pink salmon escapement

estimates and numbers of carcasses

examined for tags by fishing area, 1984

and 1985. . . . . . . . . . . . . . . .

Table 28. --Numbers of pink salmon tagged in major

Canadian rivers (adjusted for straying),

numbers recovered in the rivers, and the

recovery rate (%) by tagging year. . . .

Table 29. --Estimates of total numbers of tagged

pink salmon escaping to Alaskan and

Canadian spawning systems by general

area and period of release, 1982. . . .

Table 30. --Estimates of total numbers of tagged

pink salmon escaping to Alaskan and

Canadian spawning systems by general.

area and period of release, 1984. . . .

. . . 77

. . . 78

. . . 79

. . . 80

. . . 81

. . . 82

. . . 83
X

Table 31.--Estimates of total numbers of tagged

pink salmon escaping to Alaskan and

Canadian spawning systems by general

area and period of release, 1985. . . . . . . 84

Table 32. --Number of tagged pink salmon released,

total number estimated as caught or

escaping, percentage of estimated total

recoveries from catch and escapement,

and estimated recovery rate (2) in catch

or escapement, by release fishery,

1982. . . . . . . . . . . . . . . . . . . . . 85

Table 33. --Number of tagged pink salmon released,

total number estimated as caught or

escaping, percentage of estimated total

recoveries from catch and escapement,

and estimated recovery rate (Z) in catch

or escapement, by release fishery,

1984. . . . . . . . . . . . . . . . . . . . . 86

Table 34. --Number of tagged pink salmon released,

total number estimated as caught or

escaping, percentage of estimated total

recoveries from catch and escapement,

and estimated recovery rate (%) in catch

or escapement, by release fishery,

1985. . . . . . . . . . . . . . . . . . . . . 87

Table 35.-- 1982 stock-composition estimates (%) of

pink salmon by release area and period,

totals for Alaska and Canada (%), and

estimated numbers of tagged fish in

Alaskan and Canadian escapements (%).

Best estimates of escapements were used,

and recovery rate of primary-tagged

entrants in Canada was assumed equal to

that of secondary-tagged fish. Dash

indicates no recovery in escapement

samples. . . . . . . . . . . . . . . . . . . . 88

Table 36.-- 1984 stock-composition estimates (%) of

pink salmon by release area and period,

totals for Alaska and Canada (%), and

estimated numbers of tagged fish in

Alaskan and Canadian escapements (%).

Best estimates of escapements were used,

and recovery rates of primary-tagged

entrants to the Skeena and Kwinamass

Rivers were assumed equal to that of

secondary-tagged fish. Dash indicates

no recovery in escapement samples. . . . . . . 90

Table 37.-- 1985 stock-composition estimates (%) of

pink salmon by release area and period,

totals for Alaska and Canada (%), and
xi

estimated numbers of tagged fish in

Alaskan and Canadian escapements (%).

Best estimates of escapements were used,

and recovery rates of primary-tagged

entrants to the Skeena and Kwinamass

Rivers were assumed equal to that of

secondary-tagged fish. . . . . . . . . .

Table 38. --Estimated percentage of Alaskan-origin*

pink salmon (bootstrap standard error in

parentheses) by fishery and period of

release, 1982. Dash indicates no

estimate could be made. . . . . . . . .

Table 39. --Estimated percentage of Alaskan-origin'

pink salmon (bootstrap standard error in

parentheses) by fishery and period of

release, 1984. Dash indicates no

estimate could be made. . . . . . . . .

Table 40. --Estimated percentage of Alaskan-origin'

pink salmon (bootstrap standard error in

parentheses) by fishery and period of

release, 1985. Dash indicates no

estimate could be made. . . . . . . . .

Table 41. --Numbers of tags recovered in escapements

and catches of pink salmon by area and

period of release in 1982. . . . . . . .

Table 42. --Numbers of tags recovered in escapements

and catches of pink salmon by area and

period of release in 1984. . . . . . . .

Table 43. --Numbers of tags recovered in escapements

and catches of pink salmon by area and

period of release in 1985. . . . . . . .

Table 44. --Estimated percentages of Alaskan-origin

pink salmon by fishery and period of

release for which 10 or more tags were

recovered in catch and escapement

sampling in 1982, 1984, and 1985. . . .

Table 45.--Estimated season stock compositiEc$s

based on catch-weighted averages of

half-monthly percentages of pink salmon

in northern boundary fisheries bound for

the other country, 1982, 1984, and

1985. . . . . . . . . . . . . . . .

Table 46.--Effects of different estimates of

Alaskan and Canadian escapementsa and

Canadian secondary-tagging mortality on

estimated percentages of Canadian pink

salmon in Alaskan fisheries, 1982, 1984,

and 1985. . . . . . . . . . . . . . . .

. . . 92

. . . 94

. . . 95

. . . 96

. . . 97

. . . 98

. . . 99

. . . 100

. . . 101

. . . 102
xii

Table 47 .--Effects of different estimates of

Alaskan and Canadian escapements' and

Canadian secondary-tagging mortality on

estimated percentages of Alaskan pink

salmon in Canadian fisheries, 1982,

1984, and 1985. . . . . . . . . . . . . . . . 103
xiii

LIST OF FIGURES

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

1. --International boundary area of southern

Southeast Alaska and northern British

Columbia, place names, and associated

area codes to help identify where

returning adult salmon were tagged,

1982-85. . . . . . . . . . . . . . . . .

2. --ADFtG Southeast Alaska statistical areas

101 and 102. . . . . . . . . . . . . . .

3. --ADFtG Southeast Alaska statistical areas

103 and 104. . . . . . . . . . . . . . .

4. --ADF&G Southeast Alaska statistical areas

105-108. . . . . . . . . . . . . . . . .

5. --British Columbia subareas l-10 through

1-18 of area 1 in Dixon Entrance, 1984.

6. --British Columbia subareas l-l through

l-5 (Langara Island) and 101-4 through

101-10 of area 1 in Dixon Entrance,

1985. . . . . . . . . . . . . . . . . .

7. --British Columbia areas 3 through 5. . .

8. --1982 and 1983 stock-composition estimates (%) of sockeye salmon by area and

period of release. Best estimates of

escapements were used, and primarytagged entrants in Canada were assumed

to experience the same loss rates in

rivers as secondary-tagged fish. Blanks

indicate no recoveries were made; a bar

indicates the stock-composition estimates are based on fewer than 10 tag

recoveries from releases in this fishery

and period. . . . . . . . . . . . . . .

9. --1982, 1984, and 1985 stock-composition

estimates (%) of pink salmon by release

area and period. Best estimates of escapements were used, and primary-tagged

entrants to Canadian streams with

secondary tagging were assumed to

experience the same recovery rates as

secondary-tagged fish. Blanks indicate

no recoveries were made; a bar indicates

stock-composition estimates are based on

fewer than 10 tag recoveries from

releases in this fishery and period. . .

. . . 107

. . . 108

. . . 109

. . . 110

. . . 111

. . . 112

. . . 113

. . . 114

. . . 120

Joint U.S.-Canada salmon research in the international.

boundary area off the coasts of southern Southeast Alaska and

northern British Columbia has emphasized development and

application of stock-separation techniques for resolving

salmon-interception issues and improving management of Pacific

salmon resources of the region. A major component of these

studies was a sockeye (Oncorhynchus nerka) and pink (0. gorbuscha) salmon-tagging project, coupled with incidental

tagging of chum salmon (0. keta), conducted from 1982 through

1985. Sockeye salmon were tagged in 1982 and 1983. Pink

salmon were tagged in 1982, 1984, and 1985. Each year, tagging was conducted simultaneously in fisheries of southern

Southeast Alaska and northern British Columbia by the Alaska

Department of Fish and Game (ADF&G), contracted by the National Marine Fisheries Service, and by LGL Limited, Environmental

Research Associates, Sidney, B.C., contracted by the Canada

Department of Fisheries and Oceans. The immediate purpose of

tagging was to provide estimates of stock composition in

Alaskan and Canadian fisheries of the international boundary

area, for assessing numbers of fish from each country intercepted in fisheries of the other nation. In addition, tagging

provided information on the coastal migrations of salmon

useful for managing fisheries of the region. This report

describes each tagging experiment and the assessment of stock

composition in the boundary fisheries. The Glossary at the

end defines terms that may be unfamiliar.

3

Purse-seine, gill-net, and troll vessels similar to those

used in a commercial fishery in a given area were chartered to

capture adult pink and sockeye salmon. The salmon were

caught, tagged, and released throughout the season in locations within southern Southeast Alaska fisheries of Sumner

Strait, Clarence Strait, Tree Point, Cordova Bay, Noyes Island, and Dall Island (Fig. 1). Similar fishing and tagging

operations occurred within northern British Columbia fisheries

 of Dixon Entrance, Hecate Strait, and Portland Inlet. These

operations in the coastal fisheries were termed primary taggings to distinguish them from subsequent secondary taggings

conducted on fish which had escaped these fisheries. Methods

for secondary taggings will be discussed later.

Petersen disk tags, used during the 1982 and 1983 field

seasons, were replaced by spaghetti tags in 1984 and 1985

because fish with Petersen disk tags were probably more vulnerable to fishing gear, disk tags easily fouled in commercial

nets, and ancillary studies indicated equal or higher recovery

rates of spaghetti tags over disk tags (English et al. 1984).

Greater numbers of tagged fish escaping the fisheries would

result in better estimates of stock composition for the

release fisheries. Both tag types were colored the highlyvisible international orange, uniformly labeled with instructions for return, and numbered serially.

Tag-recovery efforts were directed toward both spawning

grounds and commercial fisheries to determine numbers and

places where tagged fish released from each fishery were

caught or escaped to spawning grounds. Tags were recovered

from commercial fisheries through wide-scale port-sampling

programs in both Southeast Alaska and British Columbia. For

each fishing area, information obtained included estimates of

numbers of fish caught, numbers examined for tags, and tag

identification numbers. Substantial proportions of catches of

each fishery were examined for tags, and estimates of total

number of tagged fish caught from any release in any fishery

were obtained by simple" expansion of numbers of tags observed

(to account for the unexamined catch).

As with the commercial catches, the number of tagged fish

in the spawning escapements of either country could not be

directly counted. Instead, these numbers were estimated for

both sockeye and pink salmon by examination of portions of

escapements for tagged fish and appropriate expansion of the

numbers of tags recovered to account for the unexamined escapements. Procedures differed between countries and species.

In all cases, recovery of tagged fish in escapements was

accomplished at weirs across streams, from spawning-ground

foot surveys, or from fisheries in terminal areas where stock

origins were evident.
4

In Canada, both tagged sockeye and pink salmon were

recovered at weirs. However, not all Canadian weirs were

operated each year of the tagging experiments.

The largest populations of sockeye salmon in the boundary

area occur in Canada in the drainages of Nass and Skeena

Rivers. Weirs near Babine Lake (Skeena) and Meziadin Lake

(Nass) allowed enumeration of major portions of escapements to

these rivers and capture of tagged fish. To recover additional tagged sockeye salmon, Canada established weirs on the

following less-important lake systems in northern British

Columbia: Tahltan Lake (Stikine River drainage), Devon Lake,

Bonilla Lake, and Eden Lake.

Canada could not examine escapements to many sockeye

salmon grounds south of the boundary area that potentially

contained tagged fish; outlet rivers from these grounds occur

along the central and southern Canadian coasts and Vancouver

Island coastline. Monitoring some catches from southern

British Columbia, however, partially covered these stocks and

recovered tagged fish which otherwise would have been missed.

A weir intended primarily to recover tagged pink salmon

was placed on the Yakoun River of the Queen Charlotte Islands

in northern British Columbia. Escapement sampling from weirs

in Canada is described later under individual experiments.

Weirs were used in Southeast Alaska to recover tagged

sockeye salmon, but none were built to recover pink salmon.

When the tagging program was planned, sockeye salmon stocks of

northern Southeast Alaska were not thought to contribute

significantly to boundary-area fisheries. The Chilkat and

Chilkoot Rivers are the major sockeye salmon systems of northern Southeast Alaska, and the ADF&G routinely operates weirs

on both rivers to obtain management information. During the

1982 and 1983 tagging years, combined escapements to these two

rivers equaled at least 50% of that estimated for all of

southern Southeast Alaska, yet only a few tagged sockeye

salmon from releases in the boundary-area fisheries were

observed at these weirs and only one tag was recovered.

Therefore, the initial supposition that the main Alaskan

stocks involved in the boundary-area fisheries were from

southern Southeast Alaska appears correct.

Southern Southeast Alaska has numerous sockeye salmon

systems, though none with escapements of the magnitude of

Canada's Nass or Skeena Rivers. Only part (roughly one-third

to one-half) of the total escapement of sockeye salmon to

southern Southeast Alaska could be examined for tags at weirs.

The weirs were located mainly on lake systems that were large

'S. A. McPherson, fishery biologist, ADF&G, Region 1, P.O. Box 240020,

Douglas, AK 99824-0020, pers. commun.
5

producers of sockeye salmon, including Hugh Smith Lake,

McDonald Lake, Naha River, Kegan Lake, Karta Lake, Sarkar

Lake, Hetta Lake, Klakas Lake, Klawock Lake, Salmon Bay Lake,

Chuck Lake, and Tamgas Lake. As in Canada, not all weirs were

operated in both years of sockeye salmon tagging. Details are

in Pella et al. (1988) and are summarized later under

individual experiments.

Spawning-ground foot surveys were also used to recover

tagged salmon in both countries. During the pink salmon

taggings, regular surveys were conducted on 316-388 streams i

Alaska and 20-60 streams in British Columbia, depending on

tagging year. Tagged sockeye salmon were also sought during

foot surveys on 13-17 lake systems in Southeast Alaska and

within the Skeena, Nass, and Fraser Rivers in British

Columbia. Numbers of tagged fish recovered during foot

surveys were expanded to account for numbers in the portions

of escapements not examined.

n

Recovery of primary-tagged fish entering the Nass and

Skeena Rivers was expected to be incomplete. Unmonitored

subsistence fishing occurred within the rivers. Shedding of

tags and mortality of tagged fish seemed likely because of the

great distances (240 km on the Nass River and 480 km on the

Skeena River) fish migrated to the weirs. Tagged fish on'

spawning grounds within the river systems not covered by the

weirs might be missed by foot survey crews or even migrate to

unsurveyed spawning grounds.

Secondary, riverine tagging experiments (as opposed to

primary-tagging in the coastal fisheries) on sockeye salmon

were performed in the Nass and Skeena Rivers to develop expansions for recoveries at the weirs and from foot surveys to

estimate total numbers of tagged entrants to the rivers. Proportions of primary-tagged entrants recovered in the rivers

were estimated by the known proportions of secondary-tagged

fish recovered at the weirs and from foot surveys. A basic

assumption in this procedure was that the expected percentage

of primary-tagged entrants recovered equaled that of the

secondary-tagged fish. This assumption will be scrutinized

and effects of alternative assumptions on analyses of the

tagging experiments will be determined.

In Alaska, secondary taggings were also conducted on

several sockeye salmon stocks in both 1982 and 1983 (Pella et

al. 1988) to estimate total escapement to systems without

weirs by expanding their estimated average escapement per

system by the number of such systems. Such estimates of total

escapement could then be used to expand tag recoveries at

weirs for those missed in systems without weirs. The estimated average escapement per system was determined for a

sample of systems without weirs from a combination of Petersen

tagging experiments adjusted for mortality of tagged fish and

foot-survey counts expanded to account for unobserved fish.
6

The estimate of total escapement of sockeye salmon to various

ADF&G statistical areas of southern Southeast Alaska was the

sum of the known escapements to systems with weirs and the

estimated escapements to systems without weirs. Finally,

numbers of tagged fish recovered at weirs were expanded to

estimate total numbers of tagged fish for all systems of a

statistical area. The expansion was based on the assumption

that the expected recovery percentage of tagged fish from all

escapements to the statistical area equaled the percentage of

its total escapement covered by the weirs. Riverine tag loss

in advance of the weirs was considered negligible because

outlet streams were short;

1 km or less.

maximum distance to any weir was

Secondary tagging of pink salmon was also conducted in a

number of Alaskan streams in 1982, but the practice was

abandoned when large numbers of tagged fish were observed to

migrate from the intertidal tagging locations of target

streams to other streams (Jones and Thomason 1983). Usefulness of secondary tagging of Alaskan pink salmon stocks was

questionable in view of the observed migration patterns of

these fish.

Secondary tagging of pink salmon was also conducted on a

number of Canadian stocks subsequent to fish reaching their

natal streams. These fish were tagged to estimate percentages

of primary-tagged entrants to the streams that were unobserved

for whatever reason (e.g., tag shedding, mortality, capture in

unmonitored native food fisheries, or limited examination of

spawning escapements), so that counts of primary-tagged fish

could be expanded to estimate total numbers escaping to the

spawning grounds. Canada studied major escapements of the

Skeena, Kwinamass, Khutzeymateen, and Yakoun Rivers. In the

Skeena and Yakoun Rivers,

within the rivers.

fish to be tagged were captured

Tagging was conducted at the mouth of the

Kwinamass and Khutzeymateen Rivers. Numbers of secondarytagged pink salmon that strayed and which were either caught

in fisheries or detected in other escapements were estimated,

and corresponding numbers initially released were reduced by

these estimates before the percentages recovered in the

Canadian escapements were computed.

Finally, the ADF&G estimated pink salmon escapements to

southern Southeast Alaska. Counts from repeated aerial

surveys of escapements to most of the significant stocks in

Southeast Alaska are obtained each year as part of the routine

fisheries-management program. The maximum of such counts from

a stream was expanded by a factor to estimate total escapement (Hoffman et al. 1984). Similarly, Canadian fishery

M. Seibel, Alaska Department of Fish and Game, Commissioner's Office,

P.O. Box 25526, Juneau, AK 99802-5526, pers. commun.
7

officers on foot surveys counted pink salmon escapements in

northern British Columbia.

estimate total escapement'.

These counts were also adjusted to

3

K. English, LGL Limited, Environmental Research Associates, 9768 Second

St., Sidney, B.C. V8L-4P8, Canada, pers. commun.

9

ASSUMPTIONS, DATA ANALYSIS, AND LIMITATIONS

Assumptions

Two assumptions are fundamental in the use of primary

tagging to determine stock composition and numbers of salmon

intercepted in fisheries of the boundary area. First,

representative samples of stocks comprising the mixtures in

fisheries must be tagged. In this study, the number of

tagging vessels necessarily was small compared to those of the

commercial fisheries because of costs of employing crews and

vessels. Undoubtedly, coverage of fisheries in time and space

was restricted, so stock composition of fish actually tagged

probably deviated from that of the catch in the fisheries.

However, limited coverage would not bias -estimated stock composition in fisheries in the sense that abundances of certain

stocks would be consistently overestimated or underestimated

during their time of passage through the fisheries.

Second, migratory behavior must not be severely affected

by tagging. If migration routes or destinations were altered

by tagging, results of the experiments could not be easily

extrapolated to the salmon stocks of the region. Comparison

of scale features of tagged and untagged fish in escapements

of these studies showed no evidence of pronounced altering of

destinations due to tagging (Oliver and Walls 1985). Migration may be delayed for a period of some days to several weeks

after tagging,,judging from results of freshwater tagging of

sockeye salmon (Greenough 1971). Bevan (1962) observed that

movements of many of the sockeye salmon tagged in the coastal

fishery of Kodiak Island were probably reduced for about

48 hours after tagging. If recovery of normal movement for

most tagged fish occurs within a few days, the effect on

stock-composition estimates would probably be unimportant.

Our assumption is that choices of routes and destinations were

unaffected by tagging.

Data Analysis

Primary tagging of returning adult salmon to determine

stock composition in interceptive fisheries relied on

1) release of tagged fish in the fisheries of concern, and

2) enumeration of these fish, or estimation of their numbers,

when their stock origins became evident. Relative numbers of

tagged fish of a release belonging to each stock contributing

to the interceptive fishery would then provide the estimates

of stock composition in that fishery. However, although

4

J. Eiler, Auke Bay Laboratory, National Marine Fisheries Service, NOAA,

11305 Glacier Hwy., Juneau, AK 99801-8626, pers. commun., September 1989.
10

recovery of tagged fish in escapements and some catches

provided clear evidence of stock origins, substantial numbers

were recovered in subsequent catches of other interceptive

fisheries; hence, stock origins of these fish remained unknown. (Had the stock origins of the tagged fish been evident

in the interceptive fisheries, stock composition in the release fishery would have simply and correctly been estimated

by relative numbers from the contributing stocks occurring in

combined catches and escapements.) Importantly, even though

the stock origins were unknown, the recoveries could not be

ignored.

Stock composition of the survivors of any group of tagged

salmon released in a fishery was probably altered by intervening fisheries as the individuals migrated toward their various

spawning streams. In particular, tagged fish of Canadian

stocks released from an Alaskan fishery, such as Noyes Island,

encountered intervening fisheries of both British Columbia and

Alaska; however, Alaskan fish of the release mainly encountered Alaskan fisheries. On the other hand, tagged fish of

Alaskan stocks released from a Canadian fishery, such as area

4 in Hecate Strait, encountered fisheries of both Canada and

Alaska; however, Canadian fish of the release encountered

mainly Canadian fisheries. The proportions caught of the various stocks comprising the initial release group would differ.

As a result, the relative numbers in escapements to the stocks

comprising the release group were not the same as they were at

the time of release in the originalfishery. To correct stock

composition based on only relative numbers in escapements, the

number of tagged fish subsequently caught in intervening fisheries was allocated to stocks and combined with tagged fish in

escapements.

The correction for tagged fish caught in intervening

fisheries omits tags shed by fish during encounters with

fishing gear. Petersen disk tags were probably more likely

than spaghetti tags to be shed by entanglement in nets, and

such shedding would also alter stock composition of surviving

tagged fish as they migrated to their spawning grounds. Substantial percentages of tagged fish of each experiment were

not accounted for by catches and escapements; presumably some

of the missing tagged fish had shed their tags. Information

for estimating numbers of tags shed during the experiments was

not obtained.

The procedure by which recovered tags in catches were

allocated to stocks was described by Gazey (1983). The proportion of recoveries from primary tagging in any fishing area

destined for any stock (this is the estimate of that stock's

unknown actual proportion in the release fishery) was computed

as that stock's proportion of the total recoveries from the

primary-tagged release group; these recoveries were either

found in the escapement to that stock or allocated to that
11

stock from tags caught in intervening fisheries. Tags recovered in intervening fisheries were allocated to stocks by the

estimates of stock proportions in each interceptive fishery

where they were captured. Although the allocation of recovered tags in catches involved use of the estimates of stock

proportions desired (and so appears circular), this allocation

and calculation of stock composition for all fishing areas was

done in a single mathematical operation next described.

The procedure by which tags caught in intervening fisheries were allocated and stock composition was computed can be

illustrated by considering the general situation in which S

stocks occur in mixtures in F fisheries. Tagged fish must be

released in each fishery. Numbers of tagged fish from these

releases subsequently caught in each intervening fishing area,

and numbers returning to each spawning stock are presumed

known. Let the following definitions apply:

E is the number of tagged fish released in fishing area

f which escaped to stock s;

C is the number of tagged fish released in fishing

area f that were subsequently caught in fishery f’;

T, is the total number of tagged fish released in fishing

area f that were recovered; and

pf, is the proportion of tagged fish in fishing area f

that we're destined for stock s,

where s = 1,2,...,S; f = 1,2,...,F; and f’ = 1,2 .... F.

Simple relationships among the catch and escapement recoveries

were proposed (Gazey 1983) by which to allocate tags caught in

intervening fisheries and compute the estimates of stock

composition for each fishery:

(1)
12

Each equation in the set above refers to recoveries of

tagged fish of a particular stock from one release area. Each

equation can be restated in words as follows: the number of

tagged fish recovered in the escapement to any stock s, plus

the sum across fisheries of the caught tags multiplied by corresponding proportions from stock s, equals the total number

of tagged fish recovered times the proportion destined for

stock s. More simply yet, the numbers of tagged fish which

escaped to stock s plus caught tagged fish allocated to stock

s equals the total number of recovered tagged fish from the

release area which were destined for stock s. Values of all

variables are known except for the p-variables. However, the

F p-variables occur linearly in the F equations, so their

values can be easily determined from the other known values.

The p-variables are the estimates of stock composition from

tagging. Solving the system above for the p-variables provides the estimates of proportions of fish in each fishing

area which came from stock s. Solving S such systems for

their p-variables provides the complete set of stockcomposition estimates for all S stocks in all F fisheries.

Although allocation of caught tags by the equation system

appears reasonable on superficial examination, closer inspection reveals an aspect of dubious validity. Tagged fish

subsequently caught in any intervening fishery are assigned by

the procedure in the same proportions to the stocks regardless

of where (i.e.,

tagged.

which fishery) the fish originally were

(Notice in the equation system above that the same F

p-variables occur in each of the F equations.) However, fish

tagged at Noyes Island and caught in Canada's area 3X, for

example, could be destined for different stocks, or probably

could occur in different proportions to the same stocks than

those caught in the same area but originally released from

Canada's area 4. However, tagged fish from the two areas are

allocated in the same proportions.

Numerical simulation studies indicate that the procedure

provides reasonably accurate estimates of stock composition if

numbers tagged in fisheries were in proportion to abundance.

However, estimates of stock composition became inaccurate when

numbers tagged were not in proportion to abundance (Gazey et

al. 1983). The tagging program was conducted with the intent

to approximate such proportional tagging. Violations of

proportional tagging presumably induced errors in the stockcomposition estimates. We could not evaluate the magnitude of

such errors because the potential degree of deviations from

proportional tagging was unknown.

Significant numbers of tagged fish could not be accounted

for by catches and escapement estimates. Soon after release,

many may have died from the stress of tagging. The loss of

tagged fish through such mortality was simply equivalent to
13

releasing fewer tagged fish in the fisheries if fish of the

various stocks were equally susceptible to stress. Therefore,

had actual numbers of tagged fish released been proportional

to abundance, tagged survivors should also have been proportional to abundance, provided the percentage surviving the

tagging was uniform among release fisheries. However, even

given that tagging was proportional to abundance, numbers of

survivors from tagging stress might not have been proportional

to abundance if survival rate varied among release fisheries;

later results show considerable apparent variation among

release fisheries in percentage of tagged fish accounted for

by catches and escapements.

In summary, essential data for calculation of stock

composition in each interceptive fishery were the numbers of

tagged fish released from each fishery which subsequently

escaped to each contributing stock and corresponding numbers

of tagged fish caught in each intervening interceptive

fishery. This information was needed for all significant

interceptive fisheries before stock composition could be

calculated for any of them. Next described are details of the

application of Equation (1) shared by all the tagging

experiments.

Releases of tagged sockeye and pink salmon were

stratified into half-month periods: 15-30 June, l-15 July,

16-31 July, and l-15 August. Some tagged fish used in the

analyses were released before 15 June or after 15 August;

these were included in the nearest period. Such stratification allows a straightforward comparison of stock composition among years. However, numbers of tagged fish recovered

from releases of some fisheries and half-month periods were

too small to reliably assess stock composition. Information

concerning the number of recoveries and precision of stockcomposition estimates for each fishery and time stratum is

provided so that the reader will be warned of unreliable

estimates.

Tagged fish were also stratified into areas of release.

Areas of release correspond to the interceptive fisheries of

concern; their definitions are provided in Tables 1, 2, 3 and

Figs. 2-7. The area definitions are straightforward, but some

explanation of the subdivisions of Canada's Dixon Entrance is

provided.

During the course of the studies, Canada developed areal

statistical systems for increasing resolution, primarily within the open water of Dixon Entrance. At the beginning of the

studies in 1982, open water of Dixon Entrance was treated as a

single statistical area; it was divided into nine areas in

1984 (Fig. 5), and redefined into seven areas in 1985 (Fig.

6) l Areas with few tagged-fish releases were aggregated into'

larger units (Table 3; Figs. 5, 6) with greater total numbers

of releases.
14

Catches were stratified by weeks and fishing areas. The

boundary fishing areas included ADF&G statistical areas 101

through 108 in Southeast Alaska and areas 1, 3X, 3Y, 3Z, 4, 5,

and 6 in northern British Columbia. Within the British

Columbia portion of the boundary area, area stratification was

no finer, but in Alaska, fishing areas were further subdivided

because of higher area resolution of the Alaskan statistical

system.

Fishing areas outside this border region were generally

monitored only incidentally to other management activities by

agencies of either country. However, Canada began monitoring

the Johnstone Strait fishery at Vancouver Island for tagged

sockeye salmon in 1983 after tagged fish unexpectedly appeared

in catches.

Numbers of fish examined for tags from catches were

available by statistical week, gear, and fishing area, and

also by ADF&G statistical subarea for Alaskan fisheries. The

total numbers of tagged fish in Alaskan catches (by half-month

period and area of release, and week and area of recovery)

were estimated by expanding numbers of tagged fish recovered

in the weekly catch samples to account for unexamined catches.

Statistical records from Canadian fisheries were less

refined than those from Alaskan fisheries, and records were

inadequate to determine with certainty the size of weekly

catch from which samples were obtained (Gazey et al. 1983;

English et al. 1984). However,

fishing area was available.

the season catch by gear and

Therefore, the total numbers of

tagged fish in Canadian catches (by half-month period and area

of release, and week and area of recovery) were estimated by

expanding numbers of tagged fish recovered in the weekly catch

samples by each gear in the recovery area for an estimate of

the part not examined. The estimate of the part of the weekly

catches not examined was the season portion of the catch by

the gear in the recovery area that was unexamined.

Total numbers of tagged fish that were part of the

escapements to spawning stocks of either country (from

releases of a half-month period and area) were estimated by

expanding numbers of tagged fish recovered at weirs or during

foot surveys on streams to account for portions of the escapements not examined for tags. Various methods were used to

estimate the percentages of the escapements examined (or the

complementary percentages unexamined) for tagged fish. We

describe these methods under the individual experiments.

Estimates of stock composition in the fishing areas

during a release period were computed from the basic equation

system for tag recoveries (Equation 1). We substituted estimates for unknown quantities of the equations before solving

for the stock proportions (p-variables). Estimated numbers of

tagged fish from release areas, which were subsequently caught
15

in intervening fishing areas, were substituted for the

corresponding unknown values in the equations. Similarly,

estimated numbers of tagged fish which escaped to major individual stocks or regional groups of stocks were substituted for

the corresponding unknown values in the equations. We then

solved the equation system for the percentages from major

individual stocks or regional groups of stocks in the fisheries; the solutions were our point estimates of stock

composition in each fishery and period.

The bootstrap approach (Efron and Tibshirani 1986) was

used to evaluate potential error in the point estimate of

stock composition due to subsampling catches and escapements

for tagged fish. This procedure consisted of drawing samples

with replacement and equivalent size from actual samples.

These bootstrap samples were used to estimate numbers of

tagged fish in escapements and catches, just as the actual

samples were used in computing the original point estimates.

Bootstrap values for numbers in escapements and catches were

substituted into Equation (1), which was solved for the stock

percentages when possible.

Resampling of samples, estimation of numbers of tags in

catches and escapements, and recomputation of stock percentages were repeated 100 times for each experiment. By this

procedure, we determined empirically the variation in estimates of the stock percentages in the fisheries, which was

induced by subsampling escapements and catches. We used the

standard errors of the bootstrap estimates of stock percentages as a measure of their precision. A rule of thumb

regarding the precision of a reported estimate of a stock

percentage in a fishery is as follows: in 95 of 100 imagined

repetitions of the samplings of catches and escapements for

tags during the tagging experiments, the unknown actual stock

percentage in the fishery would be within two standard errors

of the reported estimate. Therefore, a small standard error

for a reported stock percentage indicates the estimate was not

subject to much variation due to subsampling catches and

escapements. Contrariwise, if the standard error was large,

then the reported estimate of the stock percentage may have

been poorly determined because of subsampling errors.

In some cases, stock percentages could not be recomputed

from the bootstrap samples because Equation (1) became

singular. Equation (1) became singular if no recovery

occurred in the bootstrap samples from releases in one or more

fisheries. If such singular cases were rare among the 100

repetitions, they were simply omitted from our evaluations of

precision; that is, the empirical distributions were based on

corresponding reduced numbers of bootstrap estimates of stock

percentages. When singular cases became frequent, the

fisheries causing the singular problem were omitted from the

evaluation. This practice led to mildly optimistic estimates
16

of precision by understating the variation in stock

composition estimates induced by subsampling.

In addition to the bootstrap results regarding precision,

observed numbers of tag recoveries in escapements and catches

are reported; these recoveries are classified by half-month

period and area of release. If tag recoveries were few,

especially in escapements, the estimates of stock composition

from that release were viewed skeptically. In a few cases,

bootstrap evaluation of possible error in stock-composition

estimates did not reflect the obvious uncertainty due to few

recoveries; therefore, numbers of recoveries were considered

when judging reliability of estimates.

Furthermore, the bootstrap evaluation of variation in

stock-composition estimates due to subsampling catches and

escapements did not include errors incurred from estimating

escapements of salmon in spawning systems without weirs.

Neither did the evaluation account for possible bias in

estimates of tagged fish in escapements from possible

differences between in-river recovery rates of primary- and

secondary-tagged fish. To evaluate such errors and differences, estimation of stock composition was repeated for ranges

of possible escapements and recovery rates. To compare these

analyses, catch-weighted averages were computed of half-month

estimates of Alaskan and Canadian percentages for a fishery

using percentage of the season catch in each period as the

weight for the corresponding half-month stock percentage.

Such catch-weighted averages are inherently important because

they represent the stock composition of the catch for the

entire season in the fishery. If no reliable estimate of

stock composition was available in a fishery during a halfmonth period, the unreliable estimate available was combined

with a reliable estimate of an adjacent period, or the

estimate from the adjacent period was simply substituted for

the period that lacked an estimate altogether. Specifically,

for a period with an unreliable stock-composition estimate, a

weighted average of the estimate and the estimate from an

adjacent period was computed; numbers of tagged fish recovered

in the periods were used as the weights. Only if 75% or more.

of the catch for the season in a fishery was covered by

reasonably reliable estimates of stock composition was a

catch-weighted average computed. The 75% criterion was chosen

to limit the reported catch-weighted averages to those least

distorted from the underlying season stock composition because

of missing estimates of stock composition within the season.
17

SOCKEYE SALMON TAGGING EXPERIMENTS OF 1982 AND 1983

Primary Tagging in the Fisheries

A total of 40,455 sockeye salmon were tagged in 16

general areas during 1982 (Table 4). Numbers tagged varied

substantially among areas; fewer than 100 fish were tagged in

Cordova Bay and Dixon Entrance, but other areas had well over

1,000 tagged fish. In 1983, the tagging program was reduced

(Table 4). Total number of tagged fish released during 1983

was 21,293 --about one-half the number of the previous year.

Tagged sockeye salmon were released in 13 areas--with more

than 1,000 released in 8 of the areas.

Fishery Recoveries

Estimates of total numbers of primary-tagged fish

subsequently caught in intervening fisheries in Alaska and

Canada are provided by area and period of release for either

year (Tables 5 and 6); these estimates were obtained by summing estimates over statistical areas in Alaska or Canada.

The vast majority of tagged fish released in British Columbia

waters and caught in intervening fisheries were recovered in

Canadian fisheries. Canadian fisheries also recovered substantial portions of tagged fish caught from Alaskan releases.

The broad implication of these recoveries is clear: given

that significant fisheries and sockeye salmon catches occurred

in both Alaska and Canada, most tagged sockeye salmon were

migrating toward Canadian waters. However, catches of tagged

fish alone are not sufficient to estimate stock composition in

fisheries.' The number of tagged fish escaping to the spawning

grounds in Alaska and Canada must also be considered.

Terminal Recoveries

Corresponding estimates of total numbers of tagged fish

in escapements were obtained by expanding numbers of tagged

fish recovered at weirs and from riverine fisheries to account

for unexamined fish or incomplete recovery of tagged fish

entering rivers with weirs. Expansions for Alaskan escapement

were based on numbers of sockeye salmon examined for tags at

weirs and on estimates of total numbers escaping to southern

Southeast Alaska (Pella et al. 1988). These numbers (weir

counts and estimates) are provided for Alaskan fishing

districts (Table 7).

Weirs on the Skeena River system at Babine Lake and the

Nass River system at Meziadin Lake were used to recover tagged

fish in both years. The weirs accounted for most of the

primary-tag recoveries in both the Skeena River (92% in 1982
18

and 94% in 1983) and Nass River (98% in 1982 and 99% in 1983).

The weirs also accounted for most of the secondary-tag recoveries in the Skeena (96% in 1982 and 99% in 1983) and Nass

Rivers (94% in 1982 and 99% in 1983). Foot surveys of spawning grounds in the two river systems accounted for the

additional recoveries.

Based on the results of secondary tagging, many primarytagged sockeye salmon entering the Skeena and Nass Rivers were

not recovered at the weirs or by the spawning surveys. The

estimated percentage of secondary-tagged sockeye salmon recovered ranged from only 17% to 61% (Table 8).

have died, shed their tags,

Tagged fish may

been caught in unsampled native

food fisheries, been undetected during foot surveys, or

migrated to unsurveyed spawning grounds.

fish avoided capture at the weirs,

Although some tagged

this was not an important

cause for the shortfall in recoveries.

In 1983, Canada released secondary-tagged sockeye salmon

at three locations along the Skeena River (English et al.

1984). Recovery rate at the Babine weir ranged from 22% for

estuary releases, to 2% for a midway location, and 7% for the

uppermost site about 140 km upriver. Corresponding recovery

rates from these tagging locations when foot-survey recoveries

were included with the weir recoveries were 25, 2, and 7%.

Secondary tagging within the Nass River in 1983 also

resulted in only a combined 6% recovery rate for the Meziadin

Lake weir and foot-survey recoveries. The recovery rate at

the Meziadin Lake weir from releases in the nearby ocean

fishery (area 32) was greater than that from releases within

the Nass River.

River was

The outcome of secondary tagging in the Nass

similar to that in the Skeena River; that is,

recovery rate at the Babine Lake weir of tagged sockeye salmon

released in the estuary of the Skeena River was also considerably greater than that of tagged fish released within the

river.

Observed recovery rate during 1983 was inconsistent with

the initial supposition that both primary- and secondarytagged fish would be recovered at similar rates. Clearly,

recovery rates of primary-tagged fish entering the Skeena and

Nass Rivers are not well known.

We adopted interim estimates of recovery rates proposed

by LGL Limited analysts (Gazey et al. 1983; English et al.

1984) (Table 8) for our initial analyses. In 1983, the observed recovery rate for salmon tagged in the estuary of the

Skeena River was 25%, which was slightly higher than the 1982

recovery rate based on in-river tagging (17%). The recovery

rate for the Nass River in 1983 (61%) was simply the midpoint

of a range of possible values considered extreme by LGL

Limited analysts, which was higher than the 1982 rate (43%)

based on in-river tagging.
19

Numbers of primary-tagged salmon recovered at the weirs

and during foot surveys of- spawning grounds in the Skeena and

Nass Rivers were expanded to estimate initial numbers entering

the rivers; the expansions were based on recovery rates of

secondary-tagged sockeye salmon (Table 8). This procedure for

estimating numbers of primary-tagged entrants follows closely

that used earlier by LGL Limited analysts (Gazey et al. 1983;

English et al. 1984).

In addition to examining major escapements of the Skeena

and Nass River systems, Canada extended their coverage in 1983

to include the Stikine River, Johnstone Strait, and several

smaller sockeye salmon systems. A secondary-tagging program

was conducted by Canada on the Stikine River in 1983 to

estimate the number of primary-tagged fish returning to this

system; the Canadian commercial fishery in the Stikine River

was the recovery mechanism for tagged fish, analogous to the

weirs on the Skeena and Nass Rivers. In 1983, a total of

862 sockeye salmon were tagged in the river below the U.S.-

Canadian border on the U.S. side, and 187 (22%) of these

tagged fish were recovered in the fishery. Numbers of

primary-tagged fish in the catches were expanded correspondingly to estimate total numbers in the river.

Johnstone Strait represented a fishery located between

Vancouver Island and the British Columbia mainland rather than

a spawning ground. Unexpectedly, this Canadian fishery, far

south of the boundary area, caught primary-tagged sockeye

salmon released in 1983 (English et al. 1984). Evidence of

their origin was limited, but the Fraser River--a major

sockeye salmon system which enters the Pacific Ocean south of

the fishery--was the logical primary source. Four 1983 tags

occurred within the escapement to the Pitt River, which enters

the Fraser River about 48 km above its mouth. Eleven live,

tagged sockeye salmon were observed during index counting of

escapement at the Hell's Gate fishway 200 km above the mouth

of the Fraser River by Pacific Salmon Commission personnel,

but subsequent foot surveys of the Fraser River system above

Hell's Gate produced5 only a single tag--from the stream bottom

of the Seymour River. A single tag, volunteered from the

sport fishery of Lake Washington, showed sockeye salmon from

Washington State were also probably at Johnstone Strait;

however, the Washington State contribution was probably small.

Estimated total return of sockeye salmon to the Fraser River

was more than lo-fold that of sockeye salmon from Washington

State in 1983.

5

Dr. James Woodey, Chief Biologist, Fishery Management, Pacific Salmon

Commission, No. 600, 1155 Robson St., Vancouver, B.C. V6E-lB9, Canada,

pers. commun., 28 October 1991.
20

Although the Johnstone Strait fishery was not sampled by

personnel of the tagging program until 20 August, fishermen

volunteered recoveries as early as 12 July. After 20 August,

volunteer recoveries from fishermen comprised about 42% of the

tagged fish in catches (as estimated from program sampling).

Recoveries volunteered by fishermen before program sampling

were assumed to equal 42% of the primary-tagged fish of these

catches. Therefore, the analysis included the entire return

through Johnstone Strait of the presumed Fraser River-origin

tagged sockeye salmon.

Weirs were installed on Devon, Bonilla, and Eden Lakes--

coastal systems supporting minor (compared to the Skeena,

Nass, and Stikine Rivers) Canadian sockeye salmon populations.

Losses of tags in the short rivers leading to these lakes were

assumed negligible, so numbers of tags recovered at these

weirs were treated as the total escapement of tagged fish.

Estimates of total numbers of tagged fish escaping to

spawning areas in Alaska and Canada are provided by period and

general area of release for each year (Tables 9 and 10).

During both years, the vast majority of sockeye salmon tagged

throughout the season in Canadian fisheries escaped to

Canadian river systems. Also, more tagged sockeye salmon

released during the season from several Alaskan fishing areas

(e.g., Noyes Island, Dall Island, and Tree Point) escaped to

Canadian than to Alaskan spawning areas; but the disparity in

recovery rates was not as great as for spawning-area recoveries of releases from Canadian fishing areas. Furthermore, at

times more tags from releases of some Alaskan fisheries were

recovered in Alaskan escapements than in Canadian escapements

(e.g., Lower Clarence Strait and Revillagigedo Channel in the

first period of 1982, Middle and Upper Clarence Straits and

Revillagigedo Channel in the second period of 1982, Upper

Clarence Strait throughout 1983, and Sumner Strait from the

second period of 1983 onward).

Numbers of tagged sockeye salmon released at most

locations in either year exceeded the combined estimates of

recoveries in catches and escapements to Alaska and Canada,

often by wide margins (Table 11). The overall recovery rate

of total releases from Alaska or Canada accounted for by estimates of tagged fish in catches and escapements was consistent

with findings of secondary tagging in saltwater estuaries in

Alaska. Ancillary experiments during secondary-tagging studies in Alaska included release of tagged sockeye salmon captured purse seining by hand adjacent to the mouths of several

outlet streams with weirs to count them (Pella et al. 1988).

Counts at the nearby weirs and recoveries from all weirs, foot

surveys, and commercial and subsistence fisheries of Southeast

Alaska could not account for roughly 40% of these secondarytagged fish. Tagged fish may have shed their tags or died

from the effects of tagging (Pella et al. 1988). However,
21

shedding of a substantial percentage of tags was improbable

because the fish had less than 1 km to migrate to the weir on

the way to their spawning grounds. More likely, tagged fish

died from tagging stress, either directly or indirectly due to

their increased vulnerability to predation.

Similarly, primary-tagged sockeye salmon released in

Alaska and Canada, which were not accounted for in catch or

escapement, may have died from tagging stress or predation,

shed their tags, been caught in native food fisheries, or

migrated from the region to unmonitored spawning grounds.

Such overall loss of tags from Alaskan tag releases was 50% in

1982 and 39% in 1983 (loss = 100% minus recovery rate from

last pair of columns of Table 11). Corresponding estimates of

overall loss for Canadian releases in those years were 13% and

43%. Only the loss from Canadian releases of 1982 (13%) was

inconsistent with a conjecture, based on the experience of

secondary tagging in Alaska, that around 40% of primary-tagged

fish may have died from tagging stress. However, recovery

rate varied substantially among release locations, and was far

greater than 60% (conjectured survival rate from tagging

stress) for many locations in either year.

Estimated percentage of tagged fish in catches and

escapements from two Canadian release locations (areas 3Y and

4) was l0l-105% in 1982. Generally, recovery rates in catches

or escapements from Canadian release locations during 1982

were high compared to Alaskan releases of both years, or

Canadian releases of 1983. Recovery rates among Alaskan

locations in either year were comparatively high for Lower

Clarence Strait, Revillagigedo Channel, and Tree Point.

Possibly the apparently high recovery rates of fish

tagged in Canadian release locations and nearby Alaskan locations in Lower Clarence Strait, Revillagigedo Channel, and

Tree Point were caused partly by overestimates of tagged fish

in Canadian escapements to the Nass and Skeena Rivers--the

destinations of most fish released from these tagging locations. Estimated numbers of primary-tagged fish in escapements to the Nass and Skeena River systems depended inversely

on estimates of recovery rates of these fish after they

entered the rivers. If the recovery rate of primary-tagged

entrants was underestimated, primary-tagged fish escaping to

these systems was overestimated. If this were the case, then

estimated numbers of primary-tagged fish accounted for by

catches and escapements (Table 11) could exceed 100%. As

mentioned earlier, interim estimates of recovery rates of

primary-tagged entrants to these rivers proposed by LGL

Limited analysts (Gazey et al. 1983; English et al. 1984) were

used (notwithstanding our questions of their accuracy) to compute estimates of numbers of primary-tagged fish in Canadian

escapements. The discussion below (see Sensitivity Analysis,
22

p. 24) explains why recovery rates of primary-tagged entrants

to the Canadian systems may have been underestimated.

Furthermore, numbers of tag recoveries in some Canadian

catches possibly were over- or underestimated because proportions of the catches sampled in the various Canadian fisheries

varied during the season. Such variation could not be

accounted for when actual recoveries were expanded to estimate

total recoveries. (For Canadian fishing areas, the weekly

proportions of catches examined for tags were not available,

so the proportions sampled for the entire season were used to

expand actual tag recoveries to total tag recoveries.) The

expansions were applied to tagged fish recovered in Canadian

catches from both Canadian and Alaskan release locations,

possibly accounting for the high recovery rate from releases

of some Alaskan locations.

The observed variation among release locations in

percentage of tags accounted for by catches and escapements is

not satisfactorily explained by uniform mortality rates from

tagging stress, overestimation of tagged fish in Canadian

escapements, or errors in estimates of tagged fish caught in

Canadian fisheries. Most fish released at Noyes Island, Dall

Island, and Langara Island were destined for the Skeena and

Nass Rivers and many were caught in Canadian fisheries, yet

recovery rates from these locations remained comparatively low

both years. Recovery rates also remained comparatively low

for other release locations--such as Sumner Strait, Upper

Clarence Strait, Middle Clarence Strait, and Union Bay--less

dominated by Nass and Skeena River stocks. Whatever causes

may underlie the variation in recovery rate among the release

locations, the apparent effect varied among locations and

between years of tagging.

Stock-Composition Estimates

Estimates of total recoveries in catches and escapements

by location and period of release were used to compute stock

composition in fisheries (Tables 12, 13) by the algorithm

described earlier. Skeena and Nass River stocks were abundant

throughout much of the region during the entire season; Nass

River stocks returned earlier than Skeena River stocks (Fig.

8) l Southern stocks passing through Johnstone Strait in 1983

were in the boundary area mainly from mid-July to the end of

tagging (Fig. 8). Along the outer-coast fisheries, abundance

of the southern stocks peaked during August, constituting an

estimated 58% and 30% of sockeye salmon at Langara Island and

Noyes Island, respectively. The main Alaskan stocks in the

fishing areas originated in ADF&G statistical areas 101 and

102.
23

Generally, greater changes occurred in stock composition

estimates from Alaskan releases than Canadian releases after

tags recovered in intervening fisheries were allocated to

stocks (Tables 12, 13); that is, percentages of Alaskan or

Canadian fish in combined escapements (last pair of columns)

from Alaskan releases often changed substantially (next to

last pair of columns) after caught tagged fish were allocated.

As expected, estimates in the percentages of tagged Canadian

sockeye salmon in Alaskan fisheries increased substantially

after the allocation of caught tags because tagged fish released in Alaskan fisheries and destined for Canadian spawning

grounds were exploited in intervening Alaskan and intense

Canadian fisheries, but releases destined for Alaskan systems

were exploited mainly in Alaskan fisheries.

Alaskan and Canadian percentages of Alaskan-origin

sockeye salmon in the fisheries were summarized using Alaskan

percentages; corresponding Canadian percentages can be

obtained by subtraction from 100% (Tables 14, 15). Variation

of stock-composition estimates due to subsampling catches and

escapements, but not including variation from escapement estimates, was evaluated by the bootstrap approach (Tables 14,

15). Standard errors of most estimates of stock percentages

appeared reasonably small (<55%), but several were greater.

Because credibility of estimates of stock percentages depends

partly on numbers of tagged fish recovered in escapements or

catches, these were also summarized (Tables 16, 17). As expected, estimates of stock percentages were quite unreliable

(as indicated by bootstrap standard errors) when total tags

recovered in catches and escapements was small.

Estimates of stock proportions for both years are

summarized by omitting release time and area strata for which

fewer than 10 total tag recoveries were obtained in sampling

catches and escapements (Table 18); hence, the remaining estimates generally had reasonably low standard errors based on

bootstrap results.

Discussion

Two generalities concerning Alaskan and Canadian percentages in the fisheries were evident by inspection of the results of our analysis (Table 18). First, the percentage of

Alaskan-origin sockeye salmon in Alaskan fisheries is greater

than in Canadian fisheries; hence, the percentage of Canadian

fish in Canadian fisheries is greater than in Alaskan fisheries. Second, the percentage of Canadian sockeye salmon in

Alaskan fisheries tends to be much greater than the percentage

of Alaskan sockeye salmon in Canadian fisheries.

Catch-weighted averages, of half-month stock-composition

estimates for each fishery provided estimates of season stock
24

composition (Table 19). Most sockeye salmon in Alaskan

catches were of Canadian origin (except in Sumner Strait),

whereas only a small percentage of Canadian catches were of

Alaskan origin. Contribution rates from Alaskan stocks to

Canadian fisheries were greater in 1982 than in 1983, and

contribution rates of Canadian stocks to Alaskan fisheries

were greater in 1983 than in 1982 for two of the three

fisheries where comparison was possible.

Sensitivity Analysis

Outcomes of the analyses should be considered with

circumspection. Stock-composition estimates depended heavily

on estimates of tagged fish escaping to either country. Estimates of tagged fish escaping to Alaska depended directly on

the estimate of total Alaskan escapement. Specifically, an

estimate of larger escapement to Alaska would result in an

estimate of more tagged fish escaping to Alaska; conversely,

an estimate of smaller escapement to Alaska would result in an

estimate of fewer tagged fish escaping to Alaska. The estimates of total escapements of sockeye salmon to southern

Southeast Alaska for 1982 and 1983 were 354,000 (90% confidence interval 254,000-466,000) and 324,000 (90% confidence

interval 216,000-458,000), respectively (Pella et al. 1988).

Imprecise estimates of Alaskan escapements in 1982 and 1983

possibly caused large errors in estimates of escaping tagged

fish.

Estimates of tagged fish escaping to Canadian spawning

grounds depended inversely on estimates of recovery rates of

terminal entrants to the Nass, Skeena, and Stikine Rivers.

Such estimates were the percentages of secondary-tagged sockeye salmon recovered at weirs and spawning grounds of the Nass

and Skeena River systems or in the commercial fishery of the

Stikine River. Estimates of lower recovery rates in the

Canadian systems would result in estimates of more primarytagged fish escaping to Canada. Conversely, estimates of

higher recovery rates in Canadian systems would result in

estimates of fewer primary-tagged fish escaping to Canada.

Estimates of recovery rates of primary-tagged sockeye

salmon entering Canadian rivers (Table 8) were too low if

recovery rates of secondary-tagged sockeye salmon were less

than those of the primary-tagged sockeye salmon. The recovery

rate of secondary-tagged fish could have been substantially

less than of primary-tagged terminal entrants to the rivers if

fish died from tagging stress (similar in magnitude to that

inferred from estuarine secondary-tagging studies in Alaska)

within a few days after tagging. That is, primary-tagged

entrants had already survived tagging stress during the time

of ocean migration to the river entrance, but the secondarytagged fish could have experienced losses due to it, reducing
the percentage of secondary-tagged sockeye salmon recovered at

weirs and spawning grounds.

In 1982, secondary taggings conducted within the Nass and

Skeena Rivers were used to estimate the recovery rate of

primary-tagged sockeye salmon (Table 8). However, the estimates of recovery rate of primary-tagged sockeye salmon in the

rivers during 1983 were based on either recovery rate of estuary releases on the Skeena River or fishery releases from area

32 near the Nass River entrance. Evidence presented earlier

from secondary tagging of sockeye salmon in estuaries in

Alaska indicated that possibly 40% of estuary-tagged fish died

of tagging stress. Similarly, sockeye salmon released in

ocean fishing areas may also suffer substantial mortality, for

recoveries in catches and escapements constitute but a portion

of total Alaskan or Canadian primary-tagged releases (Table

11). Yet recovery rates at-the weirs of the Skeena River

estuary and area 32 releases during 1983 were larger than from

secondary taggings within the rivers themselves.

Further evidence for substantial mortality -from tagging

stress of returning adult sockeye salmon released in coastal

fishing areas comes from a 1949 tagging experiment at Kodiak

Island (Bevan 1962). Sockeye salmon were tagged from trap

catches, a seemingly less stressful mode of capture than the

purse seine, gill-net, and troll gear used in the present

studies. Fishermen reported only 32% of the tagged fish, even

though the tagging program emphasized recovery of tags from

the fishery. Bevan (1962) must have considered recovery of

tags from the fishery to be nearly complete because his model

of the results does not include the possibility of unreported

tag recoveries. Another 25% of the releases were observed

passing the Karluk weir, the stock considered to be the major

contributor to the fishery from which the tagged fish were

released. Escapements of other stocks may have accounted for

another 1% if tags recovered in foot surveys of these escapements constituted the same percentage of their total tagged

fish as did the tags recovered in foot surveys of the Karluk

River. If these catch and escapement recoveries are expanded

for the estimated 11% shedding loss provided by Bevan (1962),

the total tagged fish accounted for by catches, escapements,

and shedding equals only 66% of the releases. In other words,

34% were missing.

Bevan (1962) modeled these losses as a continuous process

during the return through the fishery rather than as an abrupt

mortality shortly after tagging. However, his view was based

on the outcome of an experiment which would not have detected

a large initial mortality from stress if it were not increased

by additional handling of fish being tagged. In addition to

mortality from tagging stress, the Kodiak experiment also demonstrated that the behavior of tagged fish is initially
26

affected; recovery rates in the fishery were depressed for two

days after tagged groups were released.

In summary regarding the recovery rates of primary-tagged

sockeye salmon entrants to the Nass and Skeena Rivers, we

judged that values obtained from secondary-tagging experiments

upstream within the rivers were questionable because of the

contradictory outcomes of 1983. In view of the probable

mortality of some of these fish from tagging stress shortly

after release, we also questioned whether values obtained from

estuarine or nearby fisheries provided valid estimates of such

recovery rates.

The uncertainty in actual recovery rates of primarytagged sockeye salmon in the major rivers of Canada demands

further analysis. To evaluate the effects of potential errors

in estimates of tagged fish escaping to Canadian or Alaskan

spawning grounds on the outcomes of' the analyses, the analyses

were repeated using several combinations of estimates of

Alaskan escapements and recovery rates in the Skeena, Nass,

and Stikine River systems. Three estimates of Alaskan escapements were used: the point estimate and the lower and upper

bounds of the 90% confidence interval of each year (Table 7).

Two estimates of recovery rates of primary-tagged fish in the

Canadian rivers were used, equivalent to 0% and 40% mortality

of secondary-tagged fish. A 40% tagging mortality reduced

estimates of numbers of terminal entrants to the Nass, Skeena,

and Stikine River systems to 60% of the values computed using

0% mortality.

Evaluations of the effects of errors in estimates of

tagged fish escaping to Alaska and Canada on stock-composition

estimates were computed for five combinations of estimates of

Alaskan escapement and Canadian secondary-tagging mortality

(Tables 20, 21). Almost certainly, the extremes of possible

errors were included.

As expected, estimates of larger Alaskan escapement

reduced estimates of percentages of Canadian-origin sockeye

salmon in the fisheries, and a 40% secondary-tagging mortality

further reduced the percentages (Tables 20, 21). On the other

hand, estimates of smaller Alaskan escapement increased estimates of percentages of Canadian-origin sockeye salmon in the

fisheries, and a 0% Canadian tagging mortality further increased percentages. Estimates of season stock composition in

the fisheries changed most between the combination of the

upper 90% bound on Alaskan escapement and 40% Canadian

secondary-tagging mortality and the combination of the lower

90% bound on Alaskan escapement and 0% Canadian secondarytagging mortality (compare lines 3 and 4 of Tables 20 and 21).

Regardless of the combination of Alaskan escapement and

Canadian secondary-tagging mortality, the 1982-season stock

composition in Alaskan fisheries changed by 15 percentage
27

points or less, depending on the fishery; for 1983, the

changes were 8 percentage points or less at Noyes Island, Dall

Island, Lower Clarence Strait, and Tree Point (Table 20).

Greatest changes (percentage points are indicated in parentheses below) occurred when contributions of Alaskan and Canadian

stocks were nearly equal, such as Upper Clarence Strait (10)

and Revillagigedo Channel (15) during 1982, or Upper Clarence

Strait (19) and Sumner Strait (25) during 1983. Corresponding

changes in Canadian fisheries were at most 6 percentage points

in both 1982 and 1983 (Table 21).

Concern that errors in estimating tagged fish escaping to

spawning systems of Alaska or Canada could seriously distort

estimates of stock composition and interceptions was largely

allayed for all Canadian fishing areas and the important

Alaskan fishing areas at Noyes Island, Dall Island, and Tree

Point. However, the effect on stock-composition estimates of

such extreme errors in estimating numbers of tags escaping to

spawning areas of either country was greater for some remaining Alaskan fishing areas. Nonetheless, most sockeye salmon

in Alaskan fisheries were estimated to originate from Canadian

stocks, regardless of the extremes of errors examined.

The ranges of reported estimates of season stock

composition (Tables 20, 21) understate the uncertainty in

actual season stock composition. Point estimates summarized

possible effects of errors in estimated numbers of tagged fish

escaping to Canada and Alaska. However, uncertainty in actual

stock composition included variation due to subsampling

catches and escapements; such variation was generally not

large (e.g., see standard errors of season stock-composition

estimates in Table 19), and would be superimposed on the

reported point estimates (Tables 20, 21). Finally, the

uncertainty in actual season stock composition due to the

tagged fish unaccounted for by catches and escapements remains

unmeasured.

29

PINK SALMON TAGGING EXPERIMENT OF 1982, 1984, AND 1985

Primary Tagging in the Fisheries

Large numbers of pink salmon were tagged in the boundary

waters of the United States and Canada during 1982, 1984, and

1985 (Table 22). In 1982, more than 151,000 pink salmon were

tagged in 9 Alaskan and 7 Canadian fishing areas. Even-year

stocks were tagged again in 1984, but only slightly more than

82,000 fish were tagged in 5 Alaskan and 6 Canadian fishing

areas. Odd-year stocks were first tagged in 1985; more than

125,000 fish were tagged in 10 Alaskan and 8 Canadian fishing

areas.

Fishery Recoveries

Numbers of primary-tagged pink salmon subsequently

recovered in intervening fisheries from each general area and

period of release were expanded to account for the unexamined

portion of catches to estimate total recoveries. Estimates of

total tagged pink salmon caught in Alaska and Canada were

obtained by summing estimates of total tag recoveries over

fisheries within each country (Tables 23, 24, 25).

Generally, Alaskan catches of pink salmon tagged in

Alaskan waters (other than at Tree Point) greatly exceeded

Canadian catches. On the other hand, relative numbers of

Canadian releases caught in Alaska and Canada depended more on

the year, time, and place of release.

Terminal Recoveries

Estimates of tagged pink salmon in escapements from each

general release area and period were computed from tagged fish

recovered at weirs (in a few Canadian rivers) or from the

numbers of tagged carcasses observed during foot surveys of

streams (in both Alaska and Canada). Actual tag recoveries

were expanded to account for unexamined fish or tagged fish

which entered the rivers but did not arrive at the Canadian

weirs.

Total tagged fish escaping to Alaskan systems were

estimated from numbers of pink salmon carcasses counted and

examined for tags during stream surveys, numbers of tags

recovered from the carcasses, and estimates of total escapements to southern Southeast Alaska. In 1982, a total of 569

foot surveys were made on 375 Alaskan streams. In 1984 the

total was 475 surveys on 316 streams, and in 1985 the total

was 588 surveys on 388 streams. Survey counts of carcasses

and estimated escapements were classified by ADF&G statistical

areas for each tagging year (Table 26). Observed numbers of
30

carcasses with tags were divided by the proportions of total

escapements examined during the surveys to estimate tagged

fish in the escapements. Proportions of escapements examined

were computed from the cumulative counts of carcasses examined

and corresponding escapements in groups of ADF&G statistical

areas listed (Table 26).

Expansions to estimate numbers of tagged pink salmon

returning to British Columbia spawning systems depended on the

system and were based on either 1) numbers of carcasses examined for tags combined with escapement estimates, as was done

for Alaska, or 2) results of secondary-tagging experiments.

Escapement estimates were based on counts made from foot

surveys, which were expanded to account for escapement not

seen. Numbers of carcasses examined for tags and escapement

estimates were classified by tagging year and fishing area

(Table 27). No escapement estimates were available for 1982

when only stocks of the Skeena, Kwinamass, and Khutzeymateen

Rivers (where secondary-tagging studies were conducted) were

included in the analysis.

Secondary tagging of pink salmon was conducted on the

Skeena and Kwinamass Rivers during each tagging year, but only

during 1982 on the Khutzeymateen River. The percentage of

secondary-tag releases in these rivers subsequently recovered

at weirs or during surveys was generally low and no more than

14%. The recovery rate varied among years by slightly more

than twofold for the Skeena and Kwinamass Rivers (Table 28).

Such variation could occur as amount-or effectiveness of recovery effort changed; for example, effectiveness of recovery

effort could vary with water levels of the rivers. Recovery

rate in the Kwinamass River was consistently greater than in

the Skeena River. Differences among rivers in recovery rate

was expected because the portions of escapements accessible to

survey probably differed.

Recovery rate of secondary-tagged fish was assumed to

equal the rate of primary-tagged fish in the rivers. Before

computing their recovery rate, numbers of secondary-tagged

fish released were reduced by numbers estimated to have

strayed. The number of primary-tagged fish 'observed in these

rivers was expanded to account for those unobserved by dividing by the recovery rate of secondary-tagged fish.

Estimates of total tagged fish escaping to Alaskan and

Canadian spawning streams were summarized for each tagging

year by area and period of release (Tables 29, 30, 31). These

estimates were obtained by summing estimated tagged fish in

the various escapements of Alaska or Canada. Generally, numbers of primary-tagged pink salmon escaping to Alaskan spawning streams from nearly all Alaskan release areas throughout

the season were vastly greater than numbers escaping to

Canada. Relative numbers of Canadian releases escaping to

Alaska and Canada were more dependent on time and place of
31

release than were Alaskan releases. For the first two release

periods, the combined number of Canadian releases escaping to

Alaska roughly equaled or exceeded the number escaping to

Canada; however, in the last two periods, Canadian releases

escaping to Canada greatly exceeded those to Alaska. Clearly,

fish from Alaskan stocks predominated in most Alaskan fisheries throughout the season and were more abundant in Canadian

fisheries earlier than later in the season.

Estimates of total number of recoveries of tagged pink

salmon in catches and escapements were plausible (Tables 32,

33, 34) in the sense that the numbers released at any location

in any tagging year exceeded the numbers estimated in catches

and escapements. Overall percentages of Alaskan or Canadian

releases subsequently observed in catches and escapements were

similar each year. However, in 1982, estimated overall

recovery rate was 39%; this value is considerably lower than

that of 1984 (52%) or 1985 (59%).

The type of tags used may have affected the recovery rate

of tagged salmon in catches and escapements. Petersen disk

tags were used in 1982, but spaghetti tags were used in 1984

and 1985. Possibly more pink salmon died from the use of

Petersen tags. Substantial percentages (,61%, 48%, and 41% in

1982, 1984, and 1985, respectively) of primary-tagged pink

salmon were not accounted for in either catches or escapements. Presumably the tagged pink salmon died from tagging

stress or predation, shed their tags, or migrated to areas not

completely covered by tag-recovery sampling.

Stock-Composition Estimates

Estimates of tagged pink salmon in catches and escapements were used to estimate stock composition in fisheries by

the algorithm described earlier. Estimates of percentages

contributed by regional stock groups were summarized by

release year, area, and time of season (Tables 35, 36, 37;

Fig. 9). Generally, fish from Alaskan stocks were abundant

throughout the season over much of the boundary area in all

years. The more significant contributors were Alaskan stocks

of ADF&G statistical area 101, especially early in the season.

Stocks from ADF&G statistical areas 102, 103, and 104 appeared

in substantial numbers during the latter half of the season,

especially in Alaskan fisheries (excluding Tree Point), and in

Canadian fisheries of area 1. Canadian area 3 and Skeena

River stocks were significant contributors to Canadian fishing

areas and, at times, to Tree Point, Revillagigedo Channel,

Noyes Island, and Dall Island. Pink salmon from stocks south

of the Skeena River (Canadian areas 5 through 14) were detected in 1984 and 1985. In 1984, tag recoveries in catches and

escapements occurred as far south as Canada area 6. In 1985,

escapement recoveries were made farther south in central
32

British Columbia, and catch recoveries were made even farther

south in Johnstone Strait and the western coast of Vancouver

Island. Increase in geographic range of recoveries from 1982

to the later years coincided with increased coverage of

escapements by the sampling program (recall that in 1982,

coverage of Canadian escapements was limited to the Skeena,

Khutzeymateen, and Kwinamass Rivers).

Percentages of Alaskan pink salmon in fisheries were

summarized (Tables 38, 39, 40). Precision of stockcomposition estimates, excluding variation from escapement

estimates, was evaluated using the bootstrap technique.

Standard errors of most stock-composition estimates appeared

reasonably small (15%), but some were subject to large

variation from subsampling catches and escapements for tags.

Numbers of tagged fish recovered in catches and escapements

affect the accuracy of stock-composition estimates, and

therefore were summarized (Tables 41, 42, 43). As expected,

stock-composition estimates were quite unreliable (as

indicated by bootstrap methods) when total tags recovered in

catches and escapements was small. Therefore, we summarized

what we considered the reasonably reliable estimates of stock

composition for the 3 years of tagging by omitting time and

area strata for which fewer than 10 total tags were recovered

in sampling catches and escapements (Table 44).

Discussion

Several generalities on stock distribution of pink salmon

were evident from the estimated percentages of Alaskan-origin

pink salmon in international boundary fisheries (Table 44).

First, the percentage of pink salmon of Alaskan origin caught

in Alaskan fisheries generally remained, high (>75%) throughout

the season in all tagging years. The main exceptions were at

Tree Point and Revillagigedo Channel, where the percentage

from Alaska was sometimes lower. Second, percentage of

Alaskan-origin pink salmon in Canadian fisheries varied more

among areas and years of tagging than in Alaska. The percentage of Alaskan-origin pink salmon was generally greatest in

Canadian areas adjacent to Alaska (Dixon Entrance, Langara

Island, and areas 3X, 3Y, and 3Z). Finally, the percentage of

Alaskan pink salmon in Canadian fishing areas in 1984 and 1985

was generally highest early in the season and declined later.

In 1982, the percentage of Alaskan pink salmon in the Canadian

fishing areas was also high early in the season, generally

declined through the third release period, and then recovered

in the last release period.

Catch-weighted averages of stock-composition estimates

were computed across release periods to approximate season

stock composition of the interceptive fisheries (Table 45).

Resulting averages were reasonably precise because imprecise
33

estimates of stock composition usually corresponded to release

periods with small catches. The percentage of season catches

in Alaska from Canadian stocks was low (<12%) in all years and

fisheries except Tree Point. On the other hand, the percentage of season catches in Canadian areas consisting of Alaskanorigin stocks was variable among areas and years, and ranged

to near 50% and higher for areas adjacent to Alaska, including

Dixon Entrance and area 3.

Sensitivity Analysis

All stock-composition estimates should be treated with

circumspection because their values were determined mostly

from estimated numbers of tagged fish escaping to either

Alaskan or Canadian spawning systems. Estimates of tagged

fish in escapements depended, in turn, on estimates of escapements; the accuracy of escapement estimates to each country

was unknown. However, included with the best estimates of

escapements provided by analysts of LGL Limited and ADF&G were

lower and upper bounds within which the true escapements probably occurred (Tables 26 and 27). We considered the estimates

of escapements as expert opinions, and the bounds were the

only measures of their accuracy.

Canada utilized secondary tagging to estimate numbers of

escaping primary-tagged pink salmon in several major river

systems (Table 28). Recovery rate of secondary-tagged pink

salmon was used to expand recoveries of primary-tagged fish to

estimate numbers of primary-tagged entrants to the rivers.

Similar to the sockeye salmon experiments, if secondary-tagged

pink salmon suffered losses not experienced by primary-tagged

fish after the latter entered the rivers, numbers of primarytagged pink salmon entering these rivers would be overestimated. Such bias could affect stock-composition estimates,

causing Canadian-origin pink salmon to be overestimated.

Results of behavioral experiments on pink salmon (Helle

1966) at Olsen Creek, Alaska,. were consistent with our postulated tagging mortality. On 10 dates between 29 July and

3 September 1961, Helle captured five maturing pink salmon of

each sex in Olsen Creek within tidal influence of Olsen Bay.

The fish were tagged with Petersen disk tags without the use

of an anesthetic (anesthetic was not used for primary or secondary tagging during the present study) and released several

miles away in seawater at Port Gravina, a major body of salt

water which contains Olsen Bay. Also on each date, a control

group of fish was captured, tagged, but released at the

capture location rather than being moved. Olsen Creek was

surveyed by foot daily for the tagged fish, and 12 nearby

salmon streams within Port Gravina were surveyed by foot

weekly. The totals of tagged fish which could be accounted

for from the foot surveys were 54 and 58 of the 100 released
34

from the displaced and nondisplaced groups, respectively. In

other words, 46% and 42% of the displaced and nondisplaced

groups, respectively, were not found even though the likely

places to which they might have strayed were monitored.

To evaluate effects of possible errors in estimates of

escaping tagged fish, stock-contribution estimates were recomputed under several combinations of estimates of escapements

and mortality of secondary-tagged pink salmon for the Skeena,

Kwinamass, and Khutzeymateen Rivers. The three escapement

estimates used for Alaska and Canada in each tagging year were

the lower and upper bounds and the best point estimates

(Tables 26, 27). Two choices of mortality rate of secondarytagged fish in the Canadian rivers were 0% and 40%. Assuming

a 40% mortality rate of secondary-tagged fish reduced estimates of tagged fish escaping to the Skeena, Kwinamass, and

Khutzeymateen systems to 60% of the estimates computed assuming 0% mortality. Five combinations of estimates of Alaskan

escapements and Canadian secondary-tagging mortality rates

were examined for 1982. (Recall that Canadian escapements to

systems other than those in the secondary-tagging program of

1982 were not available.) Four combinations of Alaskan and

Canadian escapements and Canadian secondary-tagging mortality

rates were examined for 1984 and 1985. Presumably, the extremes of possible errors in estimated tagged fish escaping to

Alaska and Canada were included.

Regardless of the combination of estimates or tagging

year, the season stock-composition estimates changed by only a

few percentage points in Alaskan fisheries other than Tree

Point and Revillagigedo Channel (Table 46). Some fisheries in

Canada were affected more: changes in seasonal stock-composition estimates ranged up to 21 percentage points (Table 47).

Concern that potential errors in escapement estimates or

mortality rates of secondary-tagged fish could seriously

mislead us was allayed for most fisheries.

The ranges of reported estimates of seasonal stock composition (Tables 46, 47) understate the uncertainty in actual

season stock composition. Point estimates were used to summarize possible effects of errors in estimated tagged fish

escaping to Canada and Alaska. However, uncertainty in actual

stock composition also included variation due to subsampling

catches and escapements; such variation was generally not

large (e.g., see standard errors of season stock-composition

estimates in Table 45), and would be superimposed on the

reported point estimates (Tables 46, 47).
35

DISCUSSION AND SUMMARY

Major tagging experiments on adult sockeye and pink

salmon were conducted in southern Southeast Alaska and

northern British Columbia between 1982 and 1985. Sockeye

salmon were tagged in coastal ocean fisheries during 1982 and

1983; pink salmon were tagged during 1982, 1984, and 1985.

The immediate purpose of the experiments was to assess

interceptions of fish originating in Canada or the United

States by fishermen of the other nation. In addition, the

studies provided information on timing and migration routes of

major salmon stocks which could be used in management of the

fisheries.

Primary Tagging

Returning adult salmon were captured and tagged in the

international boundary-area fisheries of Southeast Alaska and

northern British Columbia. Adults were primary tagged in

Southeast Alaska fishing areas at Noyes Island, Dall Island,

Cordova Bay, Sumner Strait, Clarence Strait, and Tree Point,

as well as in northern British Columbia at Dixon Entrance and

Hecate Strait, including near Langara Island, Dundas Island,

Tracy Bay, Boston Rocks, Stephens Island, Porcher Island,

Birnie Island, Maskelyne Island, Portland Inlet, and Canada

areas 5 and 6. Total tagged sockeye salmon released from

Alaskan fisheries were 9,050 and 9,156 in 1982 and 1983, respectively; corresponding numbers released from Canadian fisheries were 31,405 and 12,137. Totals of tagged pink salmon

released from Alaskan fisheries were 83,487, 30,502, and

68,811 in 1982, 1984, and 1985, respectively; corresponding

numbers released from Canadian fisheries were 67,854, 51,631,

and 56,801.

Fishery Recoveries

Portions of catches in boundary-area fisheries were

examined for tagged fish. Time and place of release were

identified for tagged fish recovered during catch sampling.

Total numbers of tagged fish occurring in catches of each

fishery from half-month interval releases of each fishery were

estimated by expanding numbers of tagged fish recovered in

catch samples to account for tagged fish in portions of

catches not examined for tags.
36

Terminal Recoveries

Portions of spawning escapements of both countries were

also examined for tagged fish, and time and place of release

were identified from recovered tags. Total numbers of tagged

fish arriving at various streams or regional stream groupings

from half-month interval releases of each fishery were estimated by expanding the numbers of tagged fish recovered in the

samples to account for fish which were not examined for tags,

died, or shed their tags. Several methods were used to expand

recoveries from escapements.

Sockeye salmon

Based on early migration studies and general knowledge of

sockeye salmon stocks of the region, the main Alaskan stocks

contributing to boundary-area fisheries were presumed to

originate from southern Southeast Alaska (ADF&G statistical

areas 101 through 108). Weirs were built on some larger

Alaskan lake systems for nearly complete counting of escapements and recovery of tagged fish. Additional tagged sockeye

salmon in escapements to systems without weirs were estimated

by two steps. First, fish escaping to systems without weirs

were estimated from secondary Petersen tagging experiments

adjusted for mortality of tagged fish and from foot-survey

counts expanded for unseen fish. Second, the tagged fish

among these escapements were estimated, assuming that escapements at weirs represented a random sample of tagged and

untagged fish in escapements to all systems with or without

weirs. The two-step process was applied to regional stock

groups. Ranges of possible total escapements to Alaskan

spawning grounds were broad because only a sample of 12 of the

48 known stocks in nonweired systems could be included in the

first step in either year. Total escapement to southern

Southeast Alaska in 1982 was estimated as 354,000 (90% confidence interval 254,000-477,000); in 1983 the estimate was

324,000 (90% confidence interval 216,000-458,000). Therefore,

approximately 48% (90% confidence interval 36%-67%) and 39%

(90% confidence interval 27%-58%) of the estimated total

escapements of 1982 and 1983, respectively, were examined for

tags at Alaskan weirs.

In Canada, the main stocks of sockeye salmon were

considered in 1982 to be limited to the Nass and Skeena

Rivers. Canada used weirs and foot surveys on the Nass and

Skeena Rivers to recover tagged sockeye salmon. Meziadin Lake

weir in-the Nass River system and the Babine Lake weir in the

Skeena River system were believed to cover most sockeye salmon

escapements to each system, although nonweired spawning tributaries existed in either system. In 1983, Canada extended

sampling coverage of its escapements. A commercial Canadian
37

fishery on the Stikine River was used to recover tagged

sockeye salmon. Canada also built weirs on several minor systems in the boundary area. In addition, in 1983, substantial

numbers of southward-migrating tagged sockeye salmon were

caught as far south as Johnstone Strait. Canada sampled

catches in Johnstone Strait for tagged fish to estimate total

tagged fish in catches. Most southward-migrating fish probably originated in the Fraser River, although other stocks

occur as far south as the Columbia River. Escapement to the

Fraser River equaled nearly 1 million fish and total return

was estimated as slightly more than 5 million fish in 1983

(Pacific Salmon Commission 1988). The main sockeye populations from Washington State were from the Cedar River in the

Lake Washington system and Lake Wenatchee on the Columbia

River; their combined escapements in 1983 were over 300,000

fish, and their total returns were about 380,000 fish.

Estimation of tagged sockeye salmon entering the large

Nass, Skeena, and Stikine River systems posed special difficulty because of incomplete recovery of tagged fish entering

the rivers. Some tagged fish probably migrated to spawning

grounds without weirs and were not seen during foot surveys;

others may have shed their tags, been caught in unsampled

native food fisheries on the rivers, or died from other

causes. In the Stikine River, recoveries obtained from the

Canadian commercial fishery obviously did not include all

tagged entrants. Therefore, counts of tagged fish caught in

the Stikine River fishery or recovered at weirs and during

foot surveys of spawning grounds of the Nass and Skeena

Rivers, represented only a portion of the initial entrants to

each river. Canada attempted to estimate the total tagged

entrants based on numbers of tagged fish recovered by estimating the percentage of entrants which were recovered. To estimate recovery rate, fish were captured, tagged, and released

at the estuary or locations within the rivers throughout

migration. The recovery rate of such secondary-tagged fish

was used to estimate the recovery rate of the primary-tagged

entrants to the rivers.

However, outcomes of secondary-tagging experiments on

sockeye salmon in the Skeena and Nass Rivers in 1983 were

inconsistent. Recovery rate of releases upriver was lower

than releases in the estuary or nearby ocean fisheries. If

fish tagged in the rivers were representative of ocean-tagged

entrants, the recovery rate of upriver releases should have

been no less than that of releases in estuaries or in nearby

ocean fisheries.

6

Kurt Fresh, Washington Department of Fisheries, 115 General Administration Building, Olympia, WA 98504, pers. commun.
38

LGL Limited analysts provided estimates of recovery rate

of primary-tagged sockeye salmon entering the Nass and Skeena

Rivers (Gazey et al. 1983; English et al. 1984). The recovery

rate during 1982 was based on taggings upstream within each

river. The recovery rate during 1983 for the Skeena River was

based solely on estuary tagging because of the contradictory

lower recovery rate of upriver tagging. The recovery rate

used for the Nass River for 1983 was the midpoint of a postulated range of extreme values determined partially on the

nearby ocean fishery tagging,

imum.

and partially on a proposed maxThe outcome of the taggings for the Skeena and Nass

Rivers in 1983 discredited upstream tagging for estimating the

recovery rate of primary-tagged entrants. The recovery rate

based on estuary or ocean tagging near the river entrances

appeared more plausible. However, estuary or ocean tagging

also probably induced mortality of sockeye salmon such that

their recovery rates were not representative of primary-tagged

entrants.

Substantial percentages (roughly 40%) of secondary-tagged

Alaskan sockeye salmon released in estuaries during 1982 and

1983 probably died from short-term tagging stress (Pella et

al. 1988). Further, we estimated that 34% of returning adult

sockeye salmon tagged and released in coastal fishing areas at

Kodiak Island during 1949 (Bevan 1962) were not present in

catches or escapements in which they should have occurred had

they survived.

Finally, the outcome of the present tagging experiments

confirmed a substantial loss of primary-tagged fish from the

ocean releases. Cause of the losses was not determined, but

presumably included mortality, tag shedding, and migration to

unsampled fisheries and spawning escapements. Initially, estimates of recovery rate provided by LGL Limited analysts were

used to compute primary-tagged fish in escapements to these

rivers. Later, estimates of primary-tagged sockeye salmon in

all escapements and catches were combined to estimate the

total accounted for by the experiments. Only 50% and 61% of

the tagged fish released from Alaskan fisheries subsequently

occurred in catches and escapements in 1982 and 1983, respectively. Corresponding recovery rates for releases from

Canadian fisheries were 87% and 57%.

mentary sense,

Viewed in the comple50% and 39% of primary Alaskan releases were

not found in escapements or catches of 1982 and 1983, respectively; 13% and 43% were corresponding values for Canadian

releases. Recovery rates from releases in individual fisheries varied considerably among the fisheries in both years.

In summary, we judged that the recovery rates obtained

from secondary-tagging experiments within the Nass and Skeena

Rivers are questionable in view of the contradictory outcomes

of 1983. We also questioned whether values obtained from tagging in the estuary or nearby fisheries provided valid
39

estimates of such recovery rates in view of the probable

losses from these tagged releases before they entered the

rivers. Therefore, although we initially used LGL Limited

analysts' estimates of recovery rates within the rivers for

our assessment; alternative values were tried to evaluate

effects on estimates of stock composition in the fisheries.

Pink salmon

Both Canada and Alaska had many more pink than sockeye

salmon stocks. Not only were the numbers of stocks greater,

but the total number of pink salmon returning to the boundary

area was manyfold that of sockeye salmon during the tagging

years. Pink salmon catches in boundary-area fisheries were

13, 23, and 33 million fish in 1982, 1984, and 1985 compared

to corresponding sockeye salmon catches of 3, 2, and 4 million

fish.

The difficulty in determining numbers of primary-tagged

pink salmon in escapements was vastly increased when compared

to sockeye salmon. The use of weirs to cover significant

portions of escapements to either country was impractical;

pink salmon spawning streams are far more numerous than sockeye salmon spawning systems, and the large physical size of

many streams with large numbers of fish limited use of weirs.

Similar to sockeye salmon, the only Alaskan pink salmon

stocks contributing to boundary-area fisheries were presumed

those of ADFCG statistical areas 101 through 108. Pink salmon

in Alaskan escapements were estimated by the ADF&G biologists

from counts made during regular aerial surveys of spawning

streams. These estimates and bounds, which probably contained

the actual values, were available for regions within Southeast

Alaska. We evaluated neither the accuracy of these escapement

estimates nor validity of the bounds but viewed both as expert

opinions of the analysts.

Pink salmon tags in Alaska were recovered during surveys

of spawning grounds. On the surveys, carcasses examined for

tags were counted and any tags were recovered. Estimates of

tagged pink salmon escaping to Alaskan spawning grounds from

fishery releases tagged during half-month intervals were

obtained by expanding numbers of tagged fish recovered in

escapements to account for escaping pink salmon not examined

during the surveys. These estimates of tagged fish in escapements were obtained for regions in Southeast Alaska.

Canadian pink salmon in boundary-area fisheries were initially thought to arise mainly from stocks of northern British

Columbia, but southward-migrating odd-year stocks were detected beyond the geographical range of program sampling in the

1985 tagging experiment. Numbers of these southward-migrating
40

fish could not be determined and such stocks were omitted from

our analysis.

Tagged pink salmon escaping to spawning grounds of

northern and central British Columbia were estimated from

1) stream surveys and escapement estimates from foot-survey

counts, following the procedure used for Alaska, or

2) secondary-tagging experiments in conjunction with recoveries from weirs or stream surveys. Secondary tagging of pink

salmon was conducted on the Skeena and Kwinamass Rivers each

tagging year but on the Khutzeymateen River only in 1982.

Tagged fish recovered in Canadian escapements were identified

to fishery and half-month period of release, as was done for

Alaskan escapements. The number of primary-tagged fish

recovered in any of these rivers was expanded to account for

those unobserved.

The estimates of total tagged pink salmon in boundaryarea catches and escapements from Alaskan releases were 42,

55, and 59% of the fish released in 1982, 1984, and 1985,

respectively; corresponding values for Canadian releases were

34, 51, and 59%. As with sockeye salmon, substantial proportions of primary-tagged pink salmon were apparently missing.

Possibly the number of recoveries in catches and especially

escapements were underestimated but mortality from tagging

stress, shedding of tags, and migration to unsampled fisheries

and spawning grounds were probably largely responsible.

Similar to sockeye salmon, mortality of secondary-tagged pink

salmon may have been substantial. Results of a behavioral

experiment on pink salmon (Helle 1966) at Olsen Creek, Alaska,

were consistent with a possible mortality from tagging stress

of 40% or‘ more.

Stock-Composition Estimation Method

After computing estimates of tagged sockeye and pink

salmon in catches in various fisheries and escapements, we

calculated estimates of the stock composition in the release

fisheries. Ideally, estimation of stock composition from

primary tagging in interceptive fisheries would be based

directly on relative numbers of tagged fish from any release

belonging to each contributing stock. Although the recovery

of tagged fish in escapements and some catches provided clear

evidence of origins, more tagged fish were caught in other

interceptive fisheries when compared with terminal fisheries.

Therefore, origins of most caught tagged fish were unknown.

Nonetheless, recoveries of tagged fish of unknown origin in

the catches could not be ignored because the stock composition

of survivors to escapements was altered by intervening fisheries. To correct stock-composition estimates based on relative

numbers in escapements, tagged fish caught in interceptive

fisheries were allocated to stocks and combined with tagged
41

fish in escapements. Although fish which lost their tags

should also have been included in the correction, no estimate

of their numbers was available. Estimates of the percentages

of fish from stocks or regional groups of stocks in an interceptive fishing area were then computed as the percentages of

total recoveries from the releases in that area, either in the

escapements or allocated from the catches to the stocks or

stock groups. Releases were grouped by fishery and half-month

period of the season, and corresponding estimates of stock

composition were determined for these strata.

The procedure by which we allocated recovered tags of

catches to stocks was described by Gazey (1983). Any allocation was arbitrary to some extent, in that no basis exists by

which the destinations of releases from a particular fishery,

subsequently caught in an interceptive fishery, can be

inferred from the taggings. The method of Gazey (1983) infers

the stock destinations of the mix of tags originating from all

release areas subsequently caught in an intervening fishery

from the presumed-available stock composition in the intervening fishery. However, the stock composition of the component

groups of tagged fish, coming from different release sites to

the intervening fishery, almost surely varies among the

groups, yet the method allocates the tagged fish of these

groups caught by the intervening fishery as if they were the

same. Numerical simulation studies demonstrated that the

adopted procedure provided accurate estimates of stock composition if numbers tagged in fisheries were proportional to

abundance. The tagging program was conducted with the intention, at least, to approximate such proportional tagging.

However, we could not determine the degree to which this

condition was satisfied.

Stock-Composition Estimates

Sockeye salmon

Most sockeye salmon in Alaskan and Canadian catches

originated in Canada. The percentage of Alaskan-origin

sockeye salmon in Alaskan fisheries was greater than in

Canadian fisheries; only a small percentage of the catch in

Canada was of Alaskan origin. Alaskan sockeye salmon stocks

were relatively more abundant in 1982 than in 1983, compared

to Canadian stocks of those years.

As expected, the Canadian Nass and Skeena River sockeye

salmon stocks were major contributors to most fisheries of the

boundary area. Although both stocks were present throughout

the fishing seasons, the bulk of Nass River stocks tended to

return earlier than that of the Skeena River stocks. The main

Alaskan stocks originated in Southeast Alaska (ADF&G statistical areas 101 and 102). Stikine River sockeye salmon stocks
42

were significant contributors at times during 1983 in several

fisheries, including Sumner Strait and Tree Point in Alaska,

and at Langara Island in Canada. Finally, southward-migrating

stocks, presumably mainly from the Fraser River, were found in

significant percentages at times in 1983. The southwardmigrating stocks appeared most abundant in outer coastal

fisheries at Noyes Island in Alaska and Langara Island in

Canada, as well as in Canadian fisheries at the southern

portion of the study area.

Sensitivity analysis.-To evaluate the effects of possible

errors in estimates of escaping tagged fish, stock-composition

estimates were recomputed for several combinations of estimates of Alaskan escapements and mortality rates of secondarytagged fish of the Nass, Skeena, and Stikine rivers. The

three estimates of Alaskan escapements were the point estimate, and lower and upper bounds of the 90% confidence

interval. Two choices of mortality rate of secondary-tagged

fish in the Canadian rivers were 0% and 40%. Assuming 40%

mortality reduced estimates of ocean-tagged fish escaping to

the Nass, Skeena, and Stikine rivers to 60% of the values

using 0% mortality. Five combinations of estimates of Alaskan

escapement and Canadian tagging mortality were examined. The

extremes of possible errors in estimates of tagged fish

escaping were presumably included in the values used.

Regardless of the combination of estimates used,

subsequent stock-composition estimates of season catches in

Canada changed by 6 percentage points or less. Changes in

some Alaskan fisheries were greater, as much as 25 percentage

points. However, in 2 of 4 Alaskan fisheries of 1982 and 4 of

6 of 1983, changes were no greater than 10 percentage points.

Concern that errors in Alaskan escapement estimates or mortality of secondary-tagged fish severely affect stock composition

estimates was largely allayed for all Canadian fishing areas,

as well as the important Alaskan fishing areas at Noyes

Island, Dall Island, Lower Clarence Strait, and Tree Point.

Pink salmon

The catch of Alaskan-origin pink salmon in Alaskan

fisheries generally remained greater than 75% throughout the

season in all years of tagging. Only at Tree Point and

Revillagigedo Channel did the percentage drop lower. Furthermore, the percentage of Alaskan pink salmon in Canadian

fisheries was more variable among areas and years of tagging

than in Alaska; as expected, the percentage of Alaskan pink

salmon was generally greatest in Canadian areas adjoining

Alaska.
43

Finally, the percentage of Alaskan pink salmon in

Canadian fishing areas in 1984 and 1985 was generally greatest

early in the season but declined later. In 1982, the percentage of Alaskan pink salmon in the Canadian fishing areas also

was high early and generally declined until it rebounded near

the end of the season.

Pink salmon stocks from Alaska, ADF&G statistical area

101, were abundant throughout most of the boundary area,

especially early in the season for all years. Stocks from

ADF&G statistical areas 102 and 103 appeared later and

primarily in Alaskan fisheries or in Canadian fisheries of

Dixon Entrance. Canada area 3 stocks and Skeena River stocks

were significantcontributors to Canadian fishing areas, as

well as to Alaskan fishing areas bounding Dixon Entrance.

Stocks south of the Skeena River were detected in 1984 and

1985. In 1984, no tags were recovered in catches or escapements south of Canada area 6. However, in 1985, tags were

recovered in escapements as far south as central British

Columbia and in catches around Vancouver Island. Increased

geographical region of recovery of tagged fish may have

resulted from increase in Canadian recovery efforts.

Sensitivity analysis.-To evaluate the effects of possible

errors in estimates of escaping tagged fish, stock-composition

estimates were recomputed for several combinations of estimates of escapements and mortality rates of secondary-tagged

pink salmon of the Skeena, Khutzeymateen, and Kwinamass

Rivers. The three estimates of escapements to Alaska and

Canada were the upper and lower bounds and point estimates.

Two choices of mortality rate of secondary-tagged fish in the

Canadian rivers were 0% and 40%. Assuming 40% mortality of

secondary-tagged fish reduced estimates of ocean-tagged fish

escaping to the Skeena, Khutzeymateen, and Kwinamass Rivers to

60% of the values using 0% mortality. Five combinations of

estimates of Alaskan escapements and Canadian secondarytagging mortality rate were examined for 1982. (Canadian

escapements to systems other than those in the secondarytagging program were omitted for 1982.) Four combinations of

Alaskan and Canadian escapement estimates and Canadian

secondary-tagging mortality rate were examined for 1984 and

1985. The extremes of possible errors in estimates of tagged

fish escaping were presumably included in the values used.

Regardless of the combination of estimates used,

subsequent stock-composition estimates of season catches in

Alaskan fisheries (other than Tree Point and Revillagigedo

Channel) changed by only a few percentage points. In some

Canadian fisheries, stock-composition estimates of season

catches changed up to 21 percentage points. Concern that

errors in escapement estimates or mortality of secondary-
44

tagged pink salmon severely affect subsequent stockcomposition estimates was allayed for many fisheries.

Caveats and Qualifications

Information derived from the U.S.-Canada program of

tagging adult salmon in fisheries for estimation of stock

composition of catches was rife with difficulties. Stock

origins of tagged fish released from interceptive fisheries

could not be identified until they had migrated to terminal

areas. Intervening fisheries caught many tagged fish before

they could escape to terminal areas. Importantly, substantial

numbers of tagged fish apparently died from tagging stress or

shed their tags, and some may have migrated to unmonitored

spawning grounds or been caught in unsampled fisheries. The

numbers of tagged survivors released in a fishery, which

escaped to the various terminal areas, were not representative

of their original numbers at release. Correction of stockcomposition estimates,

fish in escapements,

based on relative numbers of tagged

for losses en route to the spawning

grounds only accounted for tagged fish caught in intervening

fisheries. Furthermore, this correction, which relied on the

allocation of the tagged fish in catches to stocks of origin,

was only expected to be successful if numbers of tagged fish

released were in proportion to overall stock abundance in the

fisheries. Tagging was directed to this goal, but degree of

achievement was unknown. Therefore, in the tagging years, the

stock-composition estimates presented must be considered

susceptible to this source of bias. In years without tagging,

estimation of stock composition in northern boundary-area

fisheries presents even greater difficulty.

Stock composition in the northern boundary-area fisheries

probably varies among years as magnitudes of stocks, ocean

conditions, and the fisheries themselves change. Clearly,

past or future stock contributions to northern boundary-area

fisheries vary from their levels during the tagging studies as

relative magnitudes of stocks change. As an example, the

odd-year pink salmon stocks of the Skeena River appeared to

have increased significantly in magnitude relative to

Southeast Alaska stocks after the 1985 taggings.

Migration routes of stocks are probably affected by

annual changes in oceanographic conditions of the region

(Hamilton and Mysak 1986). Therefore, an El Nino event during

1982-83 (Wooster and Fluharty 1985) with associated warmer

ocean temperatures along the western coast of Southeast Alaska

and British Columbia in 1983, as compared to 1982, would have

contributed to observed variations of stock composition of

northern boundary-area fisheries during tagging years. El

Nino events occur at irregular intervals roughly every

2-7 years, vary in strength, and presumably affect to varying
45

degrees the stock composition in northern boundary-area

fisheries.

Finally, distribution of fishing effort and associated

catch by time of season within fishing areas change because of

decisions by fishermen and fishery managers.< Because salmon

stocks have their own timings of passage through the fishing

areas, the fishery changes could alter the stock composition

of catches. Clearly, based on results of these experiments,

assessing stock composition of catches in northern boundaryarea fisheries in years without tagging will be subject to

great uncertainty.

As a final caveat, we warn that the estimates of stock

composition and interpretation of results are ours alone for

use by the United States in negotiations with Canada regarding

northern boundary-area fisheries; Canada has obtained similar

analyses of the taggings from staff of LGL Limited. We used

much of the methodology developed by LGL Limited in our

analysis; generally, their estimates of stock composition in

northern boundary-area fisheries from the taggings appear to

agree reasonably well with our estimates when we assumed, as

they did, that initial mortality of secondary-tagged fish from

stress was negligible. Unique aspects of the analyses necessarily make identification of the source of any disagreements

difficult. For example, partitioning of time of release

differed (LGL Limited chose months and we chose half-month

periods) because of individual judgments of best approach. In

a few cases, area of release was partitioned differently by us

because of interests within Alaska. Efforts are ongoing

between Canada and the United States within the Pacific Salmon

Commission to determine estimates of stock composition in

northern boundary-area fisheries that are mutually agreeable

to both countries.

47

ACKNOWLEDGMENTS

The scale of these tagging experiments required the

cooperation of many fisheries management and research

employees of Canada and the United States. We shall not

attempt to identify the many individuals involved, but

acknowledge those we knew were involved directly in the

planning and direction of these studies.

The planning of these tagging experiments was begun by

personnel of the Canada Department of Fisheries and Oceans and

the Alaska Department of Fish and Game. Brian Riddell of the

Pacific Biological Station at Nanaimo, B.C., and consultants

of Environmental and Social Systems Analysts Ltd. of

Vancouver, B.C., and LGL Limited of Sidney, B.C.,--including

Karl English, Bill Gazey, and Mike Staley--developed and

applied for Canada the basic estimation procedure we followed;

they also recommended the numbers of tagged fish to be

released in each experiment, based on simulation studies.

Staff of LGL Limited also directed the tagging and recovery of

both sockeye and pink salmon in Canada. Dave Cantillon, Gary

Gunstrom, and Mel Seibel of the Alaska Department of Fish and

Game initiated the planning of tagging and recovery in Alaska.

Jack Bailey, Bill Heard, and Jack Helle of the National Marine

Fisheries Service (NMFS) directed the planning and execution

of the recovery effort for sockeye salmon in Alaska. Jim

Olsen of the NMFS administered the program for the United

States.

We received helpful reviews of an earlier version of the

manuscript from Jim Blick and Mel Seibel (Alaska Department of

Fish and Game), and Richard Carlson and Aven Andersen (NMFS).

49

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Efron, B., and R. Tibshirani. 1986. Bootstrap methods for

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Efron, B., and R. Tibshirani. 1991. Statistical data

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50

Hoffman, S. H., L. Talley, and M. C. Seibel. 1984. U.S./

Canada cooperative pink and sockeye salmon tagging,

interception rates, migration patterns, run timing, and

stock intermingling in southern Southeast Alaska and

northern British Columbia, 1982. Technical Data Report

no. 110, 188 p. Available from Alaska Department of Fish

and Game, P.O. Box 3-2000, Juneau, AK.

Jones, J. D., and G. Thomason. 1983. Southern Southeast

Alaska pink salmon secondary tagging and escapement

enumeration studies, 1982, 13 p. In Final Report. 1982

salmon research conducted in Southeast Alaska by the

Alaska Department of Fish and Game in conjunction with

joint U.S. -Canada interception investigations. Alaska

Dep. Fish and Game, Div. Commercial Fisheries, Juneau,

AK.

Oliver, G. T., and S. L. Walls. 1985. Estimated contribution

from Alaska and Canada stocks to the catches of sockeye

salmon in southern Southeast Alaska, 1984, based on the

analysis of scale patterns, 46 p. In Alaska Department

of Fish and Game. Final Rep. 1984 salmon research

conducted in Southeast Alaska by the Alaska Department of

Fish and Game in conjunction with the National Marine

Fisheries Service's Auke Bay Laboratory for joint U.S.-

Canada interception studies, Contract no. WASC-84-00179,

June 1985.

Pacific Salmon Commission. 1988. Report of the Fraser River

Panel to the Pacific Salmon Commission on the 1987 Fraser

River sockeye and pink salmon fishing season, 48 p.

Pella, J. J., J. C. Olsen, J. H. Helle, J. H. Eiler, J. A.

Orsi, and D. G. Mortensen. 1988. Sockeye salmon

(Oncorhynchus nerka) escapements to southern Southeast

Alaska in 1982 and 1983, 33 p. U.S. Dep. Commer., NOAA

Tech. Memo. NMFS F/NWC-150.

Wooster, W. S., and D. L. Fluharty (editors). 1985. El Nino

north. Nino effects in the eastern subarctic Pacific

Ocean, 312 p. Washington Sea Grant Program. University

of Washington, Seattle.
TABLES

53

Table 1. --Delineation of general areas of release in

Southeast Alaska in terms of the Alaska Department

of Fish and Game statistical system.'

Release area Areas and subareas

Noyes Island 10430, 10435, 10440

Dall Island 10410, 10420

Cordova Bay 10311, 10325, 10328, 10330, 10340

Lower Clarence Strait 10125, 10129, 10210, 10220, 10240,

10250

Middle Clarence Strait 10270, 10280

Union Bay 10710

Upper Clarence Strait 10610, 10620, 10630

Sumner Strait 10641

Revillagigedo Channel 10123, 10130, 10141, 10153

Tree Point 10111

*The first three digits represent an ADF&G statistical area, and the

last two digits represent a statistical subarea.

page blank’
54

Table 2. --Delineation of general areas of

release in British Columbia in

terms of the Canada Department of

Fisheries and Oceans statistical

system.

Release area Areas and subareas

Langara Island l-l through l-5

3x 3.1

3Y 3.2 through 3.6

3Z 3.7 through 3.12

4 4.1 through 4.11

5 5.1 through 5.20

6 6.5 through 6.10

Table 3. --Delineation of areas of release in

Canada's Dixon Entrance in terms of

Canada Department of Fisheries and Oceans

statistical system by year: 1984 and

1985.

Release area

Areas and subareas

1984 1985

Northwest l-10 101-4

Northeast l-11,1-12 101-8

South l-16,1-17,1-18 101-7

Other l-13,1-14 l0l-5,101-6,

l-15 l0l-9,101-10
55 

Table 4. --Number of tagged sockeye salmon released

in southern Southeast Alaska and northern British Columbia, 1982 and 1983.

Release

location 1982 1983

Alaska

Noyes Island 2,813 3,047

Dall Island 1,442 1,039

Cordova Bay 29 0

Lower Clarence Strait 373 473

Middle Clarence Strait 386 0

Union Bay 114 0

Upper Clarence Strait 2,196 1,716

Sumner Strait 0 1,998

Revillagigedo Channel 617 134

Tree Point 1,080 749

Alaska total 9,050 9,156

Canada

Langara Island 7,909 4,314

Dixon Entrance 47 0

3x 10,090 2,958

3Y 5,920 1,308

3Z 1,348 2,493

4 5,637 758

5 490 306

Canada total 31,405 12,137

Totals 40,455 21,293
56

Table 5. --Estimates of total numbers' of tagged sockeye salmon

caught in Alaskan and Canadian fisheries by general area

and period of release, 1982.

Release

location

Release period

15-30 Jun 1-15 Jul 16-31 Jul 1-15 AUg

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 150 177 86 166 43 151 52 15

Dall Island 55 122 0 6 0 0 0 9

Cordova Bay 0 0 0 0 0 0 0 0

Lower Clarence Strait 16 17 10 31 0 0 10 4

Middle Clarence Strait 0 0 86 5 0 3 2 2

Union Bay 0 0 0 0 0 12 0 0

Upper Clarence Strait 0 0 124 71 99 299 35 37

Revillagigedo Channel 13 89 8 10 36 69 8 0

Tree Point 40 127 11 152 11 167 13 13

Alaska total 274 532 325 441 189 701 120 80

Canada

Langara Island 234 1,395 139 670 5 428 0 0

Dixon Entrance 0 0 3 27 0 10 0 0

3x 256 441 233 1,807 32 2,629 8 77

3Y 55 3,155 84 533 10 338 0 18

3Z 10 494 6 74 0 91 0 0

4 16 135 33 493 66 1,797 0 56

5 0 0 0 0 0 27 0 45

Canada total 571 5,620

Totals 845 6,152

498 3,604

823 4,045

113 5,320

302 6,021

8

128

196

276

*Numbers of actual tag recoveries expanded for subsampling of catches.
57

Table 6. --Estimates of total numbers* of tagged sockeye salmon

caught in Alaskan and Canadian fisheries by general area

and period of release, 1983.

Release

location

Release period

15-30 Jun 1-15 Jul 16-31 Jul 1-15 Aug

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 47

Dal1 Island 29

Lower Clarence Strait 0

Upper Clarence Strait 27

Sumner Strait 121

2 91

23 7

0 0

0 39

12 122

1 21

0 50

38 330

147 375 142 71 74

5 70 106 22 94

0 1 130 32 115

117 87 72 42 1

33 26 35 91 13

10 0 11 0 0

67 32 184 14 115

379 605 680 272 412

252 14 84

374 0 123

60 5 49

67 24 739

112 5 19

11 0 0

29

232

309

296

10

0

876 48 1,014 14 876

1,255 653 1,694 286 1,288

Revillagigedo Channel 0

Tree Point 15

Alaska total 239

Canada

Langara Island 91

3x 15

3Y 15

3Z 19

4 0

5 0

20 13

21 15

10 14

8 0

1 0

0 0

60 42

98 372

Canada total 140

Totals 379

*Numbers of actual tag recoveries expanded for subsampling of catches.
58

Table 7. --Southeast Alaskan sockeye salmon escapement and weir

counts by fishing district, 1982 and 1983.

Escapement estimates’

Weir 11,000s of fish)

Fishing counts 1982 1983

district 1982 1983 Low Best High Low Best High

101 75,570 72,616 76 106 143 72 108 153

102 55,966 31,283 58 81 109 43 64 90

103 22,213 8,327 48 66 89 33 50 71

104-108 16,042 14,023 72 101 136 68 102 144

Totals 169,791 126,249 254 354 477 216 324 458

*Estimates of total escapement and its lower (Low) and upper (High) 90%

confidence bounds are provided by Pella et al. (1988); corresponding

values for fishing districts were obtained from unreported numerical

results of Pella et al. (1988) by summing weir counts and estimates over

systems within districts.
59

Table 8. --Numbers of sockeye salmon released in secondary

tagging on the Skeena, Nass, and Stikine Rivers

(adjusted for straying), numbers recovered at weirs

or during foot-surveys of spawning grounds (Nass and

Skeena Rivers) or in the commercial river fishery

(Stikine River), and the recovery rate of tagged

fish in each river, 1982 and 1983 (Source: Gazey et

al. 1983; English et al. 1984).

1982 1983'

River Number Number Recovery Number Number Recovery

system tagged recovered rate (%) tagged recovered rate (%)

Skeena 3,325 559 17 1,698 420 25

Nass 3,049 1,305 43 150 92 61

Stikine 0 862 187 22

*In 1983, results of tagging in the Skeena River estuary (area 4.12) were

used for the Skeena River. Also in 1983, the value for number tagged on

the Nass River was concocted by LGL Limited analysts to provide the

reported value of recovery rate based on actual number recovered. The

reported value of recovery rate for the Nass River was the midpoint

between extremes determined by portion recovered from primary tagging in

area 32 and other unspecified information (English et al. 1984).
60

Table 9.--Estimates of total numbers of tagged sockeye salmon

escaping to Alaskan and Canadian spawning areas by period

and general area of release, 1982.

Release period

Release 15-30 June 1-15 July 16-31 July 1-15 August

location Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 80 303 14 20 0 170 0 12

Dall Island 49 60 5 0 0 0 0 53

Cordova Bay 0 0 0 0 0 0 0 0

Lower Clarence Strait 46 14 17 23 0 0 3 0

Middle Clarence Strait 0 0 58 0 4 12 2 0

Union Bay 0 0 1 0 10 18 1 0

Upper Clarence Strait 0 0 88 2 46 133 23 98

Revillagigedo Channel 43 33 35 7 20 58 1 5

Tree Point 8 19 14 85 35 83 8 12

Alaska total 226 429 232 137 115 474 38 180

Canada

Langara Island 102 1,251 18 209 5 229

Dixon Entrance 0 0 6 2 0 0

3x 68 379 58 770 11 2,192

3Y 7 1,057 14 657 3 199

3Z 1 44 0 95 4 122

4 12 1,405 0 299 22 1,037

5 0 0 0 0 0 6

Canada total 190 4,136 96 2,032 45 3,785 6

Totals 416 4,565 328 2,169 160 4,259 44

0

0

454

83

0

305

311

1,153

1,333
61

Table 10. --Estimates of total numbers of tagged sockeye salmon

escaping to Alaskan and Canadian spawning areas by period

and general area of release, 1983.

Release

location

Release period

15-30 June 1-15 July 16-31 July 1-15 August

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 14 73

Dall Island 9 148

Lower Clarence Strait 0 0

Upper Clarence Strait 41 3

Sumner Strait 102 131

Revillagigedo Channel 1 12

Tree Point 6 28

Alaska total 173 395 378 303 240 844 90 203

Canada

Langara Island 9 73 7 113 1 176 0 38

3x 4 385 2 394 0 375 1 146

3Y 5 269 7 220 0 53 0 110

3Z 1 408 4 287 0 537 0 66

4 0 10 0 34 0 57 0 0

5 0 7 0 5 0 0 0 0

Canada total 19 1,152 20 1,053 0 1,198 1 360

Totals 192 1,547 398 1,356 241 2,042 91 563

53 138 18 436

4 6 7 154

0 0 6 105

167 33 84 23

120 53 99 49

18 21 0 11

16 52 26 66

8 117

0 27

3 16

15 8

64 4

0 0

0 31
62

Table 11. --Numbers of tagged sockeye salmon released, combined

numbers estimated as caught or escaping, percentage

of total estimated recoveries from catch and

escapement, and recovery rate of tagged releases

estimated as occurring in catch or escapement, by

release fishery and year.

Number Total Percentage of recoveries Recovery

Release released recoveries Catch Escapement rate (%)

fishery* 1982 1983 1982 1983 1982 1983 1982 1983 1982 1983

Alaska

Noyes 2,813 3,047 1,439 1,806 58 53 42 47

Dall 1,442 1,039 359 71l 53 50 47 50

Cordova 29 0 0 0 0 0 0 0

Lclar 373 473 191 432 46 68 54 32

Mclar 386 0 174 0 56 0 44 0

Union 114 0 42 0 29 0 71 0

Uclar 2,196 1,716 1,055 759 63 51 37 49

Sumner 0 1,998 0 1,075 0 42 0 58

Revla 617 134 435 106 54 41 46 59

Tree 1,080 749 798 702 67 68 33 32

Alaska tot. 9,050 9,156 4,493 5,591 59 53 41 47

Canada

L=% 7,909 4,314

Dixon 47 0

3x 10,090 2,958

3Y 5,920 1,308

3Z 1,348 2,493

4 5,637 758

5 490 306

Can. tot. 31,405 12,137

Totals 40,455 21,293

4,685 920

48 0

9,415 2,087

6,219 1,133

941 2,463

5,676 248

389 23

27,373 6,874

61 55 39 45

83 0 17 0

58 37 42 63

67 41 33 59

72 47 28 53

46 59 54 41

19 48 81 52

59

93

105

70

101

79

58 45 42 55 87

31,866 12,465 58 48 42 52 79

51 59

25 68

51

45

37

48

91

71

74

50

44

54

79

94

61

21

-

71

87

99

33

8

57

59

*Noyes = Noyes Island; Dall = Dall Island; Cordova = Cordova Bay; Lclar =

Lower Clarence Strait; Mclar = Middle Clarence Strait; Union = Union Bay;

Uclar = Upper Clarence Strait; Sumner = Sumner Strait; Revla = Revillagigedo

Channel; Tree = Tree Point; Lang - Langara Island; and Dixon - Dixon

Entrance.
63

Table 12. --1982 stock-composition estimates (%) of sockeye

salmon by area and period of release, totals for

Alaska and Canada (%), and estimated numbers of

tagged fish in 'Alaskan and Canadian escapements

(%). Best estimates of escapements were used, and

recovery rate of primary-tagged entrants to major

rivers in Canada was assumed to equal that of

secondary-tagged fish.

Release Alaska stocks Canada stocks Total Esc.

area

a

101 102 103 other Nass Skeena AX Can. AK Can.

Alaska

Noyes

Dall

Lclar

Revla

Tree

Canada

Lang

3x

3Y

3Z

4

Alaska

Nowey

Dall

Uclar

Unionb

Mclar

Lclar

Revla

Tree

Canada

Dixon

Lang

3x

3Y

3Z

4

7 4 3 1

15 3 5 1

27 24 3 0

28 0 0 0

9 0 0 0

37 48 15 85

34 44 23 78

33 12 55 45

62 10 28 72

75 15 10 90

21 79

45 55

77 23

57 43

31 69

5 1 0 0 27 67 7 93 8 92

9 0 0 0 60 30 10 90 15 85

4 1 0 0 86 10 4 96 1 99

5 1 0 0 85 9 6 94 3 97

0 0 0 0 3 97 0 100 0 100

Release period 2: early to mid-July

10 7 3 2 21 57 22 78 41 59

14 34 0 0 31 20 48 52 100 0

14 26 0 5 18 38 44 56 97 3

0 100 0 0 0 0 100 0 100 0

27 27 0 16 16 14 70 30 100 0

21 6 0 1 16 56 28 72 43 57

52 2 0 10 24 12 64 36 83 17

8 0 0 0 35 56 9 91 14 86

17 0 0

8 1 1

5 0 0

4 0 0

1 0 0

0 46 36 18 82

1 18 71 10 90

0 22 72 5 95

1 58 37 5 95

0 79 20 1 99

1 8 88 4 96

71 29

8 92

7 93

2 98

0 100

Release period 1: June

3 0 0 0 100
64

Table 12. --Continued.

Release Alaska stocks

area'

Canada stocks Total Esc.

101 102 103 other Nass Skeena AK Can. AK Can.
65

Table 13. --1983 stock-composition estimates (%) of sockeye

salmon by area and period of release, totals for

Alaska and Canada (%), and estimated numbers of

tagged fish in Alaskan and Canadian escapements

Best estimates of escapements were used, and

recovery rate of primary-tagged entrants to major

rivers in Canada was assumed equal to that of

secondary-tagged fish.
'Nass - Nass River; Skn. = Skeena River; oth. - other; and Stik. - Stikine

River.

b

Noyes - Noyes Island; Dall = Dall Island; Sumnr = Sumner Strait; Lclar =

lower Clarence Strait; Uclar = Upper Clarence Strait; Revla -

Revillagigedo Channel; Tree - Tree Point; and Lang - Langara Island.

'Fewer than 10 tagged fish were recovered in catches and escapements from

these releases of tagged fish, and the estimates of stock composition

should be considered in light of this limited basis.
67

Table 14. --Percentage of Alaskan-origin* sockeye salmon

(bootstrap standard error in parentheses) by

fishery and period of release, 1982. Dash means

no estimate could be made.

Release fishery June

Early to Mid- to

mid-July end July August

Alaska

Noyes Island 15 (1.8) 22 (2.2) 3 (0.4) 5 (7.0)

Dall Island 23 (2.9) 48 (10.5) - 0 (0.0)

Lower Clarence Strait 55 (5.6) 28 (5.3) - 51 (17.1)

Middle Clarence Strait - 70 (4.0) 22 (16.9) 77 (19.0)

Union Bay 100 (0.0) 26 (11.0) 100 (0.0)

Upper Clarence Strait - 44 (2.9) 12 (1.3) 27 (5.8)

Revillagigedo Channel 28 (3.2) 64 (6.1) 15 (3.3) 23 (28.9)

Tree Point 10 (3.1) 9 (1.8) 14 (2.4) 58 (8.5)

Canada

Dixon Entrance 18 (5.8) 3 (0.7)

langara Island 7 (0.7) 10 (1.1) 3 (0.8)

3x 10 (1.6) 5 (0.7) 2 (0.4)

3Y 4 (1.9) 5 (0.7) 2 (0.6)

3Z 6 (2.6) 1 (0.2) 3 (1.2)

4 0 (0.1) 4 (0.7) 3 (O-7).

5 - 2 (0.6)

0 (0.5)

6 (3.3)

0 (0.0)

0 (0.0)

*Standard errors account for chance variation of recoveries from

subsampling catches and escapements, but not for errors in escapement

estimates for either Alaska or Canada.
68

Table 15. --Percentage of Alaskan-origin* sockeye salmon

(bootstrap standard error in parentheses) by

fishery and period of release, 1983. Dash means

no estimate could be made.

Release fishery June

Early to Mid- to

mid-July end July August

Alaska

Noyes Island 17 (5.4)

Dal1 Island 7 (2.5)

Lower Clarence Strait -

Upper Clarence Strait 68 (6.6)

Sumner Strait 43 (4.8)

Revillagigedo Channel 11 (11.2)

Tree Point 18 (10.0)

Canada

Langara Island 15 (5.1) 4 (0.9)

3x 2 (0.8) 1 (0.3)

3Y 3 (1.1) 3 (1.2)

3Z 1 (0.5) 1 (0.8)

4 0 (0.0) 1 (0.3)

5 0 (0.0) 0 (0.0)

18 (3.9)

27 (11.3)

51 (3.0)

51 (5.1)

30 (6.3)

15 (3.3)

4 (0.8)

4 (2.3)

3 (1.3)

35 (3.4)

52 (7.1)

0 (0.1)

10 (2.0)

1 (0.6)

0 (0.1)

1 (0.2)

1 (0.2)

1 (0.2)

4 (1.3)

0 (0.0)

2 (1.3)

27 (6.9)

40 (6.4)

-

0 (0.1)

0 (0.0)

0 (0.5)

0 (0.1)

0 (0.0)

-

'Standard errors account for chance variation of recoveries from

subsampling catches and escapements, but not for errors in escapement

estimates for either Alaska or Canada.
69

Table 16. --Number of tags recovered in catches and escapements

of sockeye salmon by area and period of release in

1982.

Release area

Early to Mid- to

June mid-Julv end July August

Esc. Catch Esc. Catch Esc. Catch Esc. Catch

Alaska

Noyes Island 130 62 11 46 30 45 2 9

Dall Island 51 43 5 2 0 0 10 4

Lower Clarence Strait 44 7 18 10 0 0 3 2

Middle Clarence Strait 0 0 45 6 5 1 2 2

Upper Clarence Strait 0 0 83 30 62 89 33 14

Cordova Bay 0 0 0 0 0 0 0 0

Tree Point 14 30 34 37 51 42 11 6

Revillagigedo Channel 45 19 28 5 31 20 3 1

Union Bay 0 0 1 0 11 4 1 0

Canada

Dixon Entrance 0 0 5 7 0 2 0 0

Langara Island 331 401 54 182 48 107 0 0

3x 166 130 199 488 427 641 76 30

3Y 445 586 255 143 51 84 19 4

3Z 20 90 39 18 41 20 0 0

4 238 49 50 121 191 433 51 15

5 0 0 0 0 1 6 52 23
70

Table 17. --Number of tags recovered in catches and escapements

of sockeye salmon by area and period of release in

1983.

June

Early to Mid- to

mid-Julv end Julv August

Release area Esc. Catch Esc. Catch Esc. Catch Esc. Catch

Alaska

Noyes Island 41 8 65 36 128 78

Dall Island 83 7 4 3 44 28

Lower Clarence Strait 0 0 0 0 34 23

Upper Clarence Strait 22 4 117 30 58 22

Tree Point 19 2 36 19 44 38

Revillagigedo Channel 8 1 22 5 5 3

Sumner Strait 86 28 55 41 45 18

Canada

Langara Island 45 19 40 60 47 20 9 8

3x 133 17 101 65 96 19 37 37

3Y 162 6 136 14 15 9 28 50

3Z 236 10 167 12 144 119 18 45

4 8 1 10 18 14 4 0 2

5 3 0 4 7 0 0 0 0

31 25

12 17

6 25

12 10

13 21

0 0

25 12
71

Table 18. --Percentages of Alaskan-origin sockeye salmon by

area and period of release for which 10 or more

tags were recovered in catch and escapement

sampling, 1982 and 1983.

Release

area

Early to Mid- to

June mid-July end July August

1982 1983 1982 1983 1982 1983 1982 1983

Alaska

Noyes Island 15

Dall Island 23

Sumner Strait

Upper Clarence Strait -

Union Bay

Middle Clarence Strait -

Lower Clarence Strait 55

Revillagigedo Channel 28

Tree Point 10

Canada

Dixon Entrance -

Langara Island 7

3x 10

3Y 4

3Z 6

4 0

5 -
72

Table 19.--Estimated season stock compositions

based on catch-weighted averages"

of half-month percentage of sockeye

salmon in northern boundary

fisheries bound for the other

country, 1982 and 1983.

Fishery Percentage from other country

1982 1983

*Catch-weighted averages were computed for a fishing

area provided that the reasonably reliable half-month

estimates of stock composition (those of release

periods for which at least 10 tagged fish were

recovered) covered at least 75% of the season catch in

the area.

b

Standard errors in parentheses account for chance

variation of recoveries from subsampling catches and

escapements but not for errors in escapement estimates

of either Alaska or Canada.

c

ne - Less than 75% of the season catch occurred

during the periods for which stock-composition

estimates were reasonably reliable.

d

n c = No catches were made in this area.

e

nt - No tagging occurred this year in this area.
73

Table 20. --Effects of different estimates of Alaskan

escapements and Canadian secondarytagging mortality on estimated season

percentages of Canadian sockeye salmon in

Alaskan fisheries, 1982 and 1983.

Alaskan Canadian

escapement tagging

(1,000s) mortality Canadian percentage in fishery

1982

Upper RevillaNoyes Clarence gigedo Tree

Island Strait Channel Point

354 0%

477 0%

477 40%

254 0%

254 40%

86 64

84 61

80 57

88 67

84 64

67 84

62 81

57 76

72 87

68 83

Range 8 10 15 11

1983

Noyes Dall Clarence Strait Sumner Tree

Island Island Lower Upper Strait Point

324 0% 94 97 97 62 51 92

458 0% 92 92 96 54 42 89

458 40% 90 90 95 52 36 86

216 0% 96 98 98 71 61 94

216 40% 94 95 98 69 55 92

Range 6 8 3 19 25 8
74

Table 21. --Effects of different estimates of

Alaskan escapements and Canadian

secondary-tagging mortality on

estimated season percentages of

Alaskan sockeye salmon in Canadian

fisheries, 1982 and 1983. Dash

means no estimate could be made.

Alaskan Canadian Alaskan percentage in fishery

escapement tagging Langara

(1,000s) mortality Island 3X 3Y 3Z 4

354 0% 5 3 4 3

477 0% 6 4 5 4

477 40% 10 7 8 7

254 0% 4 2 3 3

254 40% 7 4 6 5

Range

1982

6

1983

324 0% 2

458 0% 2

458 40% 4

216 0% 1

216 40% 2

Range 3

5 5 4

0 1 1

0 1 1

1 2 1

0 0 0

0 1 1

1 2 1

5
75

Table 22. --Number of tagged pink salmon released in

southern Southeast Alaska and northern.

British Columbia, 1982, 1984, and 1985.

Release

Location 1982 1984 1985

Alaska

Noyes Island 17,200 5,464 17,968

Dal1 Island 5,795 9,652 10,298

Cordova Bay 5,606 0 4,012

Lower Clarence Strait 12,713 6,375 7,573

Middle Clarence Strait 15,499 0 5,970

Union Bay 1,310 0 3,349

Upper Clarence Strait 6,960 0 7,152*

Revillagigedo Channel 11,321 2,937 7,458

Tree Point 7,083 6,074 5,031

Alaska total 83,487 30,502 68,811

Canada

Langara Island 3,465

Dixon Entrance 12,487

Dundas Island (area 3X) 12,749

Tracy/Boston (area 3Y) 17,624

Portland Inlet (area 3Z) 4,924

Stephens/Percher (area 4) 7,132

Area 5 9,473

Area 6 0

Canada total 67,854 51,631 56,801

Totals 151,341 82,133 125,612

0

17,293

12,195

6,490

6,003

4,534

5,116

0

5,603

9,250

8,439

7,241

7,481

5,680

7,005

6,102

*Composed of 6,108 releases from Upper Clarence Strait and

1,044 from Sumner Strait.
76

Table 23.--Estimates of total* tagged pink salmon caught in Alaskan

and Canadian fisheries by general area and period of

release in 1982.

Release period

Release 1 June-15 July 16-31 July 1-15 August 16 Aug-1 Sept

location Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 37 40 299 45 1,238

Dall Island 56 4 0 0 740

Cordova Bay 0 0 0 0 884

Lower Clarence Strait 333 24 0 0 1,263

Middle Clarence Strait 256 6 392 27 3,017

Union Bay 0 0 65 2 15

Upper Clarence Strait 25 2 229 8 268

Revillagigedo Channel 1,312 110 782 99 103

Tree Point 552 12 166 181 216

Alaska total 2,571 198 1,933 362 7,744

Canada

Langara Island 579

Dixon Entrance 300

3x 262

3Y 49

3Z 15

4 44

5 0

Canada total 1,249

Totals 3,820

220 136 106 158

17 1,706 59 1,388

167 216 648 439

123 112 232 256

44 10 337 14

10 235 849 25

0 0 22 171

581 2,415 2,253 2,451

779 4,348 2,615 10,195

51 1,706

87 509

2 737

36 694

17 395

2 0

185 5

51 633

325 309

756 4,988

191

7

18

6

5

0

2

31

109

369

3 0 0

209 398 18

816 113 559

577 620 1,465

11 31 0

797 0 0

654 0 73

3,067 1,162 2,115

3,823 6,150 2,484

*Numbers of actual tag recoveries expanded for subsampling of catches.
77

Table 24. --Estimates of total tagged pink salmon caught in Alaskan

and Canadian fisheries by general area and period of

release in 1984.

Release

location

Release period

1 June-15 July 16-31 July 1-15 August 16 Aug- Sept

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 171 77 262 124

Dal1 Island 350 91 274 155

Lower Clarence Strait 4 0 187 27

Revillagigedo Channel 98 44 90 12

Tree Point 82 141 320 541

Alaska total 705 353 1,133 859

Canada

Dixon Entranceb

l-10

l-11,-12

l-13,-14,-15

l-16,-17,-18

3x

3Y

3Z

4

5

Canada total 360 1,002 1,145 3,262 2,613 4,410 531 1,575

Totals 1,065 1,355 2,278 4,121 6,071 5,354

0 0 350 209 260 80 0 0

262 92 390 148 1,265 44 318 10

0 0 53 18 75 22 0 0

5 24 27 57 186 240 38 30

34 212 179 761 514 1,609 97 846

4 320 37 543 80 631 35 207

7 165 13 591 66 710 26 252

13 48 67 485 159 504 0 46

35 141 29 450 8 570 17 184

217 5 679 0

1,437 198 735 10

1,148 28 103 0

151 3 356 3

505 710 46 38

3,458 944 1,919 51

2,450 1,626

'Numbers of actual tag recoveries expanded for subsampling of catches.

b

See Figure 5 for reference.
78

Table 25. --Estimates of total* tagged pink salmon caught in Alaskan

and Canadian fisheries by general area and period of

release in 1985.

Release

location

Release period

1 June-15 July 16-31 July 1-15 August 16 Aug-1 Sept

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 434 47 1,312 144 2,426 39 298 0

Dall Island 245 56 663 165 1,196 74 744 5

Cordova Bay 0 0 0 0 896 5 34 0

Lower Clarence Strait 50 4 211 4 989 54 129 0

Middle Clarence Strait 31 0 42 1 342 0 654 0

Union Bay 16 0 55 0 388 2 3 0

Upper Clarence Strait 0 0 54 0 241 0 198 0

Revillagigedo Channel 265 5 354 81 310 82 1,202 0

Tree Point 9 34 169 528 55 602 34 17

Alaska total 1,050 146 2,860 923 6,843 858 3,296 22

Canada

Langara Island 125 191 89 289 132 259 0 0

Dixon Entrance 81 66 386 338 253 433 53 15

3x 0 4 3 392 130 898 153 39

3Y 9 66 9 49 68 653 28 57

3Z 6 25 7 346 22 663 6 27

4 3 5 0 422 16 594 0 2

5 0 16 31 726 16 575 4 0

6 6 38 0 236 0 571 0 148

Canada total 230

Totals 1,280

411

557

525 2,798 637 4,646 244 288

3,385 3,721 7,480 5,504 3,540 310

*Numbers of actual tag recoveries expanded for subsampling of catches.
79

Table 26. --Southeast Alaska pink salmon escapement

estimates and numbers of carcasses examined

for tags by ADF&G statistical areas, 1982,

1984, and 1985.

Statistical Escapementb

 (1.000s) Number

areas Low Best High examined

1982

101 2,851 3,634 5,050 256,386a

102 925 1,198 1,700 138,418a

103 2,795 3,584 5,018 95,331

104-108 1,607 2,057 13,117 89,877

Totals 8,178 10,473 24,885 580,012

1984

101 3,568 5,352 6,422

102 892

103-104

1,338 1,606

3,270 4,905 5,886

105-108 1,220 1,830 2,196

323,044

73,884

53,341

76,668

Totals 8,950 13,425 16,110 526,937

1985

101 3,692 5,538 5,833 285,570

102 1,118 1,677 1,766 40,109

103-104 4,559 6,839 7,203 319,834

105-108 2,815 4,224 4,448 332,357

Totals 12,184 18,278 19,250 977,870

a

Sample sizes were obtained from Gazey et al. (1983).

b

Escapement estimates were obtained from Appendix 13 of Hoffman

et al. (1984) and M. Seibel, National Marine Fisheries Service,

Alaska, (at ADF&G), P.O. Box 25526, Juneau, AK 99802-5526.
80

Table 27.--British Columbia pink salmon escapement

estimates and numbers of carcasses

examined for tags by fishing area, 1984

and 1985.

Fishing Escapement (1,OOOs)

area LowB Best High

Number

examined

l

b

2

3

c

5

Totals 1,504 1,886 2,327 817,845

896 1,086 1,277 724,000

192 250 300 56,267

256 330 450 32,528

160 200 300 5,050

3

c

150 225 270 17,754

5 175 263 315 24,749

6 1,062 1,593 1,912 106,578

7 329 494 592 39,464

8 2,300 2,500 2,700 284,405

Totals 4,016 5,075 5,789 472,950

1984

1985

*Low estimates were unexpanded foot-survey counts.

b

The Yakoun River was the stock examined for tags; a weir

missed an unknown portion of total escapement to the river

during flooding.

c

Kwinamass River was omitted from escapement estimates because

estimates of primary-tag recoveries were obtained by secondary

tagging.

Source: K. English and J. Taylor, LGL Limited, Environmental

Research Associates, 9768 Second St., Sidney, B.C., VBL-4P8,

Canada, pers. commun.
81

Table 28. --Numbers of pink salmon tagged in major

Canadian rivers (adjusted for straying),

numbers recovered in the rivers, and the

recovery rate (%) by tagging year.

River

system

Number Number Recovery

tagged recovered rate (%)

1982

Skeena 2,262 119 5.3

Kwinamass 1,345 83 6.2

Khutzeymateen 131 5 3.8

1984

Skeena 2,815 69 2.5

Kwinamass 1,477 196 13.3

1985

Skeena 4,842 127 2.6

Kwinamass 3,288 453 13.8
82

Table 29. --Estimates of total numbers of tagged pink salmon escaping

to Alaskan and Canadian spawning systems by general area

and period of release, 1982.

Release

location

Release period

1 June-15 July 16-31 July 1-15 August 16 Aug-1 Sept

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 0 0 114 0 223 16 1,739 130

Dall Island 23 0 0 0 446 57 357 0

Cordova Bay 0 0 0 0 234 19 553 0

Lower Clarence Strait 321 0 0 0 1,893 38 2,246 0

Middle Clarence Strait 512 0 770 19 1,872 0 1,986 0

Union Bay 24 0 62 0 276 0 0 0

Upper Clarence Strait 143 0 395 19 1,347 23 95 0

Revillagigedo Channel 747 19 650 17 14 17 264 0

Tree Point 23 0 236 67 57 68 193 35

Alaska total 1,793 19 2,227 122 6,362 238 7,433 165

Canada

Langara Island 111 35 32 16 0 0 0 0

Dixon Entrance 234 0 594 54 398 147 195 19

3x 183 19 207 398 83 466 74 38

3Y 37 33 99 375 179 342 499 785

3Z 0 38 354 703 14 49 32 0

4 23 0 273 145 71 1,616 0 0

5 0 0 14 0 51 588 0 247

Canada total 588

Totals - 2,381

125 1,573 1,691 796 3,208 800 1,089

144 3,800 1,813 7,158 3,446 8,233 1,254
83

Table 30. --Estimates of total numbers of tagged pink salmon escaping

to Alaskan and Canadian spawning systems by general area

and period of release, 1984.

Release

location

Release period

1 June-15 July 16-31 July 1-15 August 16 Aug-1 Sept

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 139 0 398 41

Dal1 Island 343 0 377 78

Lower Clarence Strait 24 0 106 10

Revillagigedo Channel 412 0 198 0

Tree Point 132 0 362 8

Alaska total 1,050 0 1,441 137

Canada

Dixon Entrance*

l-10

l-ll,-12

l-13,-14,-15

l-16,-17,-18

3x

3Y

3Z

4

5

0 0 186 23 109 92 0 0

154 41 341 103 355 44 24 41

0 0 33 0 0 85 0 0

16 0 33 0 49 277 0 43

115 41 249 159 115 1,594 0 2,003

165 23 165 127 395 227 16 401

82 8 296 195 216 563 16 173

0 41 16 214 33 779 0 10

33 10 33 334 0 326 0 0

Canada total 565

Totals 1,615

164

164

1,352

2,793

1,155

1,292

415 0 211 0

1,381 140 509 91

1,081 18 120 0

115 0 82 0

199 353 0 61

3,191 511 922 152

1,272 3,987 56 2,671

4,463 4,498 978 2,823

*See Figure 5 for reference.
84

Table 31.--Estimates of total numbers of tagged pink salmon escaping

to Alaskan and Canadian spawning systems by general area

and period of release, 1985.

Release

location

Release period

1 June-15 July 16-31 July l-15 August 16 Aug-1 Sept

Alaska Canada Alaska Canada Alaska Canada Alaska Canada

Alaska

Noyes Island 679

Dall Island 735

Cordova Bay 0

Lower Clarence Strait 361

Middle Clarence Strait 500

Union Bay 398

Upper Clarence Strait 0

Revillagigedo Channel 362

Tree Point 310

Alaska total 3,345

Canada

39

13

0

0

0

0

0

0

7

59

3,116 46

1,480 15

0 0

1,099 0

422 0

415 0

1,350 0

1,149 7

698 44

9,729 112

Langara Island 245 150 19 262

Dixon Entrance 103 15 974 78

3x 19 0 175 218

3Y 116 15 78 7

32 78 0 756 143

4 19 0 0 349

5 19 0 97 1,033

6 0 75 0 389

Canada total 599

Totals 3,944

255 2,099 2,479 4,013 7,703 349 6,026

314 11,828 2,591 13,181 8,031 2,039 6,345

1,365 116 320 39

1,250 0 172 92

1,570 0 41 0

1,830 92 189 0

660 0 371 7

750 0 0 0

1,026 0 254 0

310 0 233 77

407 120 110 104

9,168 328 1,690 319

181 272 0 0

161 551 0 30

187 1,524 58 1,774

1,920 649 175 663

1,454 1,250 116 563

52 1,748 0 1,088

39 1,176 0 1,075

19 533 0 833
85

Table 32. --Number of tagged pink salmon released, total number

estimated as caught or escaping, percentage of

estimated total recoveries from catch and

escapement, and estimated recovery rate (%) in

catch or escapement, by release fishery, 1982.

Release

fishery

Estimated

Number Total Percentage of recoveries recovery

released recoveries Catch Escapement rate (%)

Alaska

Noyes Island 17,200 5,683 63 37 33

Dall Island 5,795 2,229 63 37 38

Cordova Bay 5,606 2,428 68 32 43

Lower Clarence Strait 12,713 6,882 35 65 54

Middle Clarence Strait 15,499 9,255 44 56 60

Union Bay 1,310 446 19 81 34

Upper Clarence Strait 6,960 2,704 27 73 39

Revillagigedo Channel 11,321 4,796 65 35 42

Tree Point 7,083 2,379 79 21 34

Alaska total 83,487 35,117 49 51 42

Canada

Langara Island 3,465 1,396 86 14 40

Dixon Entrance 12,487 5,736 71 29 46

3x 12,749 2,827 48 52 22

3Y 17,624 5,783 59 41 33

3Z 4,924 1,652 28 72 34

4 7,132 4,088 48 52 57

5 9,473 1,820 51 49 19

Canada total 67,854 23,302 58 42 34

Totals 151,341 58,419 53 47 39
86

Table 33. --Number of tagged pink salmon released, total number

estimated as caught or escaping, percentage of

estimated total recoveries from catch and

escapement, and estimated recovery rate (%) in

catch or escapement, by release fishery, 1984.

Release

fishery

Estimated

Number Total Percentage of recoveries recovery

released recoveries Catch Escapement rate (%)

Alaska

Noyes Island 5,464 2,739 56 44 50

Dal1 Island 9,652 6,169 53 47 64

Lower Clarence Strait 6,375 2,856 52 48 45

Revillagigedo Channel 2,937 1,564 48 52 53

Tree Point 6,074 3,498 68 32 58

Alaska total 30,502 16,826 56 44 55

Canada

Dixon Entrance 17,293 6,252 67 33 36

3x 12,195 8,528 50 50 70

3Y 6,490 3,376 55 45 52

3Z 6,003 3,379 54 46 56

4 4,534 2,415 55 45 53

5 5,116 2,170 66 34 42

Canada total 51,631 26,120 57 43 51

Totals 82,133 42,946 57 43 52
87

Table 34. --Number of tagged pink salmon released, total number

estimated as caught or escaping, percentage of

estimated total recoveries from catch and

escapement, and estimated recovery rate (%) in

catch or escapement, by release fishery, 1985.

Release

fishery

Estimated

Number Total Percentage of recoveries recovery

released recoveries Catch Escapement rate (%)

Alaska

Noyes Island 17,968

Dal1 Island 10,298

Cordova Bay 4,012

Lower Clarence Strait 7,573

Middle Clarence Strait 5,970

Union Bay 3,349

Upper Clarence Strait 7,152

Revillagigedo Channel 7,458

Tree Point 5,031

Alaska total 68,811 40,748 39 61 59

Canada

Langara Island 5,603 2,214 49 51 40

Dixon Entrance 9,250 3,537 46 54 38

3x 8,439 5,574 29 71 66

3Y 7,241 4,562 21 79 63

3Z 7,481 5,462 20 80 73

4 5,680 4,298 24 76 76

5 7,005 4,807 28 72 69

6 6,102 2,848 35 65 47

Canada total 56,801

Totals 125,612

10,420 45 55 58

6,905 46 54 67

2,546 37 63 63

5,012 29 71 66

3,030 35 65 51

2,027 23 77 61

3,123 16 84 44

4,437 52 48 60

3,248 45 55 65

33,302 29 71 59

74,050 35 65 59
88

Table 35.-- 1982 stock-composition estimates (%) of pink salmon

by release area and period, totals for Alaska and

Canada (%), and estimated numbers of tagged fish in

Alaskan and Canadian escapements (%). Best estimates of escapements were used, and recovery rate

of primary-tagged entrants in Canada was assumed

equal to that of secondary-tagged fish. Dash

indicates no recovery in escapement samples.

Release

Escapement

Alaska stocks Canada stocks

area

a

Total recoveries

101 102 103 other 3 Skeena AK Can. AK Can.

Noyeeb

Dal1

Lclar

Mclar

Uclar

Tree

Revla

Unionb

Dixon

Lang

3x

4

4 0 0

96 0 0

91 0 0

73 0 0

50 0 0

92 0 0

90 0 0

50 0 0

97 0 0

86 0 0

86 1 0

48 0 0

4 0 0

5 0 0

Noyes 81

Mclar 72

Uclar 55

Tree 64

Revla

Unionb

82

56

Dixon 64

Lang 65

3x 49

3Y 22

3Z 28

4

5

b

53

55

Release period 1: 1 June-15 July

77 19 0 81 19

0 4 0 96 4

6 3 0 97 3

26 1 0 99 1

49 1 0 99 1

0 7 0 93 7

3 7 0 93 7

50 0 0 100 0

0 3 0 97 3

0 14 0 85 15

0 13 0 87 13

0 52 0 48 52

41 56 0 44 56

88 7 0 93 7

Release period 2: 16-31 July

3 0 0 14 2 84 16

1 0 21 3 3 94 6

6 0 30 6 4 91 9

2 0 0 30 3 66 34

0 0 0 16 1 83 17

1 0 28 13 1 85 15

5 2 14 12 3 84 16

4 0 0 26 5 69 31

1 0 0 34 16 49 51

1 0 10 57 10 33 67

0 0 4 66 2 33 67

3 0 8 21 14 64 36

0 0 6 32 6 62 38

100 0

100 0

100 0

100 0

100 0

94 6

100 0

100 0

76 24

91 9

30 70

0 100

100 0

100 0

98 2

95 5

72 28

90 10

100 0

92 8

66 34

33 67

19 81

29 71

65 35

100 0
89

Table 35. --Continued.

Escapement

Release Alaska stocks Canada stocks Total recoveries

area' 101 102 103 other 3 Skeena AK Can. AK Can.

Noyes

Dal1

Lclar

Mclar

Uclar

Cordv

Tree

Revla

Union

Dixon

Lang

3x

3Y

32

4

5

Noyes

Dal1

Lclar

Mclar

Uclar

Cordv

Tree

Revla

Dixon

3x

3Y

3Zb

5

Release period 3: 1-15 August

24 13 18 21 17 6 77 23 93

33 12 15 14 18 9 73 27 89

40 29 9 14 5 3 91 9 98

50 23 5 17 3 2 94 6 100

60 14 1 20 3 2 95 5 99

6 23 28 35 4 4 91 9 92

30 2 1 4 52 12 36 64 46

29 4 1 8 51 7 42 58 45

91 0 0 8 0 0 100 0 100

41 15 5 7 17 15 67 33 73

12 18 21 28 16 6 78 22 -

24 3 0 0 38 36 26 74 15

29 1 0 0 54 15 30 70 30

24 1 0 2 71 3 27 73 23

7 0 0 1 11 80 8 92 4

12 2 1 4 25 56 19 81 8

Release period 4: 16 August-l September

33 21 36 4 1 5 94 6 93

59 11 29 0 1 2 98 2 100

32 60 1 8 0 0 99 1 100

59 23 0 18 0 0 100 0 100

30 45 0 24 0 0 100 0 100

30 36 28 5 0 1 98 2 100

83 5 0 0 5 7 87 13 84

90 5 0 1 1 2 96 4 100

61 29 4 0 1 5 94 6 91

61 11 0 2 7 19 74 26 66

51 11 1 0 18 19 63 37 38

28 56 0 15 0 0 100 0 100

6 2 0 1 1 90 9 91 0

7

11

2

0

1

8

54

55

0

27

85

70

77

96

92

7

0

0

0

0

0

16

0

9

34

62

0

100

‘Noyes - Noyes Island; Dal1 = Dal1 Island; Lclar - Lower Clarence Strait;

Mclar = Middle Clarence Strait; Uclar - Upper Clarence Strait; Cordv -

Cordova Bay; Tree = Tree Point; Revla - Revillagigedo Channel; Union -

Union Bay; Dixon = Dixon Entrance; and Lang - Langara Island.

b

Fewer than 10 tagged fish were recovered in catches and escapements from

releases of tagged fish, and the estimates of stock composition should be

considered in light of this limited basis.
90

Table 36.-- 1984 stock-composition estimates (%) of pink salmon

by release area and period, totals for Alaska and

Canada (%), and estimated numbers of tagged fish in

Alaskan and Canadian escapements (%). Best estimates of escapements were used, and recovery rates

of-primary-tagged entrants to the Skeena and

Kwinamass Rivers were assumed equal to that of

secondary-tagged fish.

in escapement samples.

Dash indicates no recovery

Esc.

Release Alaska stocks Canada stocks Total recov.

area

a

101 102 103&4 other 1 3 Skeena 5-6 AK Can. AK Can.

Release period 1: 1 June-15 July

Noyes 78 0

Dal1 66 0

Tree 92 0

Revla 98

Lclarb 14

0

0

1B 53 0

1D 80 0

3X 83 0

3Y 89 0

3Z 90 0

4 54 0

5 84 0

Noyes 51 3 25 7 0 4 9 0 86 14 91 9

Dall 47 7 23 4 0 9 9 0 82 18 83 17

Tree 80 0 0 0 0 11 9 0 80 20 98 2

Revla 95 0 0 1 0 2 2 0 97 3 100 0

Lclar 78 0 1 10 0 7 3 0 89 11 91 9

1A 70 8 1 2 0 10 9 0 81 19 89 11

1B 58 15 0 7 0 7 9 4 80 20 77 23

1C 88 0 0 2 0 5 5 0 90 10 100 0

1D 74 0 0 0 0 8 17 0 74 26 100 0

3x 60 2 0 0 0 14 20 3 62 38 61 39

3Y 60 0 0 0 0 24 16 0 60 40 57 43

3Z 60 0 0 0 0 22 17 0 60 40 60 40

4 42 0 0 0 0 12 45 0 42 58 7 93

5 29 0 0 0 0 8 63 0 29 71 9 91

0 19 0 2 1 0 97 3 100 0

0 32 0 1 1 0 98 2 100 0

0 3 0 3 2 0 95 5 100 0

0 1 0 1 0 0 99 1 100 0

0 85 0 0 0 0 100 0 100 0

0 36 0 1 10 0 88 12 79 21

0 5 0 4 11 0 86 14 100 0

0 0 0 4 12 0 84 16 74 26

0 0 0 9 1 0 89 11 88 12

0 0 0 8 2 0 91 10 92 8

0 0 0 4 42 0 54 46 0 100

0 2 0 9 4 0 86 14 76 24

Release period 2: 16-31 July
91

Table 36. --Continued.
92

Table 37.--1985 stock-composition estimates (%) of pink salmon

by release area and period, totals for Alaska and

Canada (%), and estimated numbers of tagged fish in

Alaskan and Canadian escapements (%). Best estimates of escapements were used, and recovery rates

of primary-tagged entrants to the Skeena and

Kwinamass Rivers were assumed equal to that of

secondary-tagged fish.

Esc.

Release Alaska stocks

area

a

Canada stocks Total recov.

101 102 103&4 other 3 Skeena 5-14 AK Can. AK Can.

Release period 1: 1 June-15 July

Noyes 62

Dal1 85

Tree 98

Revla 95

Lclar 72

Mclar 48

Union 60

101-4 59

101-7 91

Lang 62

3X 100

91

99

4

5

b

100

99

6 33

Noyes 42 1 21 33 1 2 0 97 3

Dal1 65 8 12 11 1 1 1 96 4

Tree 89 0 0 0 9 1 0 90 11

Revla 93 3 2 0 2 0 0 98 2

Lclar 60 22 9 9 0 0 0 100 0

Mclar 38 0 0 62 0 0 0 100 0

Uclar 15 0 0 85 0 0 0 100 0

Union 25 0 0 74 0 0 0 100 0

101-4 74 9 7 6 1 1 1 97 3

101-7 43 0 1 9 7 26 14 54 46

Lang 20 1 1 1 2 15 60 23 77

3x 54 0 0 0 14 31 1 54 46

3Y 88 0 0 0 11 1 0 89 11

3Z 83 0 0 0 16 1 0 84 16

4 13 0 0 0 2 84 1 13 87

5 17 0 0 0 3 74 6 17 83

6 8 0 0 0 1 6 85 8 92

1 5 27 0 5 0 95 5 95 5

1 0 12 0 0 2 98 2 98 2

0 0 0 2 0 0 98 2 98 2

0 0 4 0 0 0 100 0 100 0

21 0 7 0 0 0 100 0 100 0

0 0 52 0 0 0 100 0 100 0

0 0 40 0 0 0 100 0 100 0

4 0 18 0 0 18 81 19 46 54

2 0 1 0 0 5 95 5 100 0

1 0 9 0 12 16 72 28 62 38

0 0 0 0 0 0 100 0 100 0

0 0 0 8 0 0 92 8 89 11

0 0 0 1 0 0 99 1 100 0

0 0 0 0 0 0 100 0 100 0

0 0 0 1 0 0 99 1 100 0

0 0 0 0 0 67 33 67 0 100

Release period 2: 16-31 July

99 1

99 1

94 6

99 1

100 0

100 0

100 0

100 0

100 0

46 54

7 93

44 56

91 9

84 16

0 100

9 91

0 100
93

Table 37. --Continued.
94

Table 38.--Estimated percentage of Alaskan-origin* pink

salmon (bootstrap standard error in parentheses) by fishery and period of release,

1982. Dash indicates no estimate could be

made.

Release fishery

Late June to Mid- to Early to Mid-Aug to

mid-July late July mid-August early Sep

Alaska

Noyes Island

Dall Island

Cordova Bay

81 (4.5)

96 (1.5)

Lower Clarence Strait 97 (1.3)

Middle Clarence Strait 99 (0.3)

Union Bay 100 (0.0)

Upper Clarence Strait 99 (0.6)

Revillagigedo Channel 93 (3.9)

Tree Point 93 (0.3)

Canada

Dixon Entrance

Overall

Langara Island

3x

3Y

3Z

4

5

97 (1.3)

85 (2.6)

87 (3.8)

48 (13.9)

44 (16.1)

93 (3.8)

84 (4.2) 77 (2.8) 94 (1.5)

73 (4.7) 98 (0.5)

91 (2.3) 98 (0.3)

91 (1.7) 99 (0.1)

94 (1.9) 94 (1.1) 100 (0.0)

85 (6.2) 100 (0.1) -

91 (4.2) 95 (1.3) 100 (0.3)

83 (6.7) 42 (12.8) 96 (1.0)

66 (8.0) 36 (8.6) 87 (3.7)

84 (3.6) 67 (3.4)

69 (6.2) 78 (3.9)

49 (4.9) 26 (6.4)

33 (6.0) 30 (7.3)

33 (6.1) 27 (19.1)

64 (6.6) 8 (2.3)

62 (19.0) 19 (4.4)

94 (3.0)

74 (6.7)

63 (4.0)

100 (0.0)

-

9 (3.1)

*Standard errors account for chance variation in numbers of

recoveries from subsampling catches and escapements but not for

errors in escapement estimates of Alaska or Canada.
95

Table 39. --Estimated percentage of Alaskan-origin' pink

salmon (bootstrap standard error in parentheses) by fishery and period of release,

1984. Dash indicates no estimate could be

made.

Release fishery

Late June to Mid- to Early to Mid-Aug to

mid-July late July mid-August early Sep

Alaska

Noyes Island 97 (1.8) 86 (5.4)

Dal1 Island 98 (1.0) 82 (5.7)

Lower Clarence Strait 100 (0.6) 89 (4.0)

Revillagigedo Channel 99 (0.9) 97 (1.2)

Tree Point 95 (3.2) 80 (3.2)

Canada

Dixon Entranceb

l-10

l-11,-12

l-16,-17,-18

3x

3Y

3Z

4

5

88 (7.5)

86 (8.5)

84 (8.5)

89 (5.6)

91 (8.3)

54 (23.0)

86 (6.3)

81 (3.0)

80 (5.2)

74 (6.7)

62 (5.3)

60 (7.4)

60 (7.7)

42 (9.0)

29 (7.4)

99 (0.5)

89 (2.6)

97 (1.0)

98 (0.8)

51 (4.0)

71 (7.7)

92 (2.4)

36 (5.4)

28 (3.1)

53 (4.4)

33 (5.2)

20 (3.4)

11 (3.5)

98 (1.5)

90 (4.7)

100 (0.2)

76 (8.3)

32 (10.8)

81 (8.6)

37 (18.2)

5 (1.0)

10 (3.4)

14 (6.0)

23 (5.6)

40 (4.6)

'Standard errors account for chance variation in numbers.of

recoveries from subsampling catches and escapements but not for

errors in escapement estimates of Alaska or Canada.

b

See Figure 5 for reference.
96

Table 40. --Estimated percentage of Alaskan-origin' pink

salmon (bootstrap standard error in parentheses) by fishery and period of release,

1985. Dash indicates no estimate could be

made.

Release Late June to Mid- to Early to Mid-Aug to

fishery mid-July late July mid-August early Sep

Alaska

Noyes Island 95 (4.0) 97 (1.0) 92 (3.4) 92 (7.4)

Dal1 Island 98 (1.3) 96 (0.8) 96 (0.6) 87 (5.9)

Cordova Bay 98 (0.4) 100 (0.0)

Lower Clarence Strait 100 (0.0) 100 (0.0) 94 (2.0) 100 (0.0)

Middle Clarence Strait 100 (0.0) 100 (0.0) 99 (0.2) 99 (1.2)

Union Bay 100 (0.0) 100 (0.0) 100 (0.1) -

Upper Clarence Strait - 100 (0.0) 100 (0.0) 100 (0.2)

Revillagigedo Channel 100 (0.1) 98 (0.7) 90 (1.6) 83 (9.1)

Tree Point 98 (2.0) 90 (1.6) 67 (4.0) 52 (12.5)

Canada

Dixon Entranceb

101-4

101-7

Langara Island

3x

3Y

32

4

5

6

81 (12.3) 97 (0.5) 95 (2.1) -

95 (1.9) 54 (12.6) 30 (4.3) 46 (11.6)

72 (7.4) 23 (3.4) 43 (5.6) -

100 (0.3) 54 (6.8) 19 (2.5) 9 (2.2)

92 (6.3) 89 (6.9) 71 (3.0) 22 (6.2)

99 (5.9) 84 (4.0) 54 (3.6) 18 (6.1)

100 (0.3) 13 (4.5) 7 (1.6) 0 (0.0)

99 (1.4) 17 (3.3) 7 (1.8) 0 (0.1)

33 (14.6) 8 (1.2) 5 (3.4) 0 (0.0)

“Standard errors account for chance variation in numbers of

recoveries from subsampling catches and escapements but not for

errors in escapement estimates of Alaska or Canada.

b

See Figure 6 for reference.
97

Table 41. --Numbers of tags recovered in escapements and

catches of pink salmon by area and period of

release in 1982.

Release area

Late June to Mid- to Early to Mid-Aug to

mid-July late July mid-August early Sept

Esc. Catch Esc. Catch Esc. Catch Esc. Catch

Alaska

Noyes Island 0 9 6 28 14 78 84 297

Dall Island 1 6 0 0 27 109 17 26

Cordova Bay 0 0 0 0 8 6 32 68

Upper Clarence Strait 12 3 29 10 86 68 8 3

Union Bay 2 0 5 4 13 9 0 0

Middle Clarence Strait 30 11 42 27 119 140 128 77

Lower Clarence Strait 15 18 0 0 135 126 204 97

Revillagigedo Channel 42 83 40 73 3 37 19 55

Tree Point 1 9 21 84 8 194 15 72

Canada

Dixon Entrance 11 28 40 92 35 156 12 61

Langara Island 11 67 3 40 0 8 0 0

3x 13 58 41 186 33 449 8 271

3Y 7 26 41 81 39 261 81 540

3Z 8 10 95 95 4 7 4 5

4 1 7 26 171 94 235 0 0

5 0 0 1 6 43 225 13 25
98

Table 42. --Numbers of tags recovered in escapements and

catches of pink salmon by area and period of

release in 1984.

Release area

Late June to Mid- to Early to Mid-Aug to

mid-July late July mid-August early Sept

Esc. Catch Esc. Catch Esc. Catch Esc. Catch

Alaska

Noyes Island 8 71 15 130 15 77 6 118

Dall Island 19 118 19 142 40 494 11 173

Tree Point 8 68 23 286 31 400 3 20

Revillagigedo Channel 25 38 12 33 7 43 5 84

Lower Clarence Strait 1 1 7 66 59 365 6 28

Canada

Dixon Entrance*

l-10

l-11,-12

l-13,-14,-15

l-16,.-17,-18

3x

3Y

3Z

4

5

0 0 14 185 9 115 0 0

9 96 24 181 20 395 2 85

0 0 2 20 5 33 0 0

1 10 2 27 37 158 3 16

 8 78 23 318 71 729 131 298

13 105 21 194 52 232 33 75

6 55 34 203 68 255 13 90

1 20 7 183 22 227 1 15

3 55 11 166 8 207 0 73

*See Figure 5 for reference.
99

Table 43. --Numbers of tags recovered in escapements and

catches of pink salmon by area and period of

release in 1985.

Release area

Late June to Mid- to Early to Mid-Aug to

mid-July late July mid-August early Sept

Esc. Catch Esc. Catch Esc. Catch Esc. Catch

Alaska

Noyes Island 42 106 190 355 72 459 18 51

Dall Island 42 96 78 241 59 286 11 141

Cordova Bay 0 0 0 0 72 156 2 7

Tree Point 17 21 42 339 31 327 14 19

Revillagigedo Channel 19 88 59 158 16 141 14 374

Lower Clarence Strait 17 17 52 63 58 268 5 30

Middle Clarence Strait 33 8 29 13 40 83 20 134

Upper Clarence Strait 0 0 101 15 67 56 20 44

Union Bay 25 5 30 17 46 100 0 1

Canada

Dixon Entrance*

101-4

101-7

101-N

101-5

101-6

101-8

101-g

101-10

Langara Island

3x

3Y

3Z

4

5

6

2 20 40 98 1 7 0 0

1 13 6 31 31 244 2 22

0 0 2 19 0 0 0 0

0 0 0 5 0 0 0 0

4 11 2 17 0 7 0 0

0 0 2 7 0 0 0 0

0 5 2 77 0 0 0 0

0 0 0 0 0 0 0 1

21 114 20 142 22 163 0 0

1 2 21 192 62 433 68 65

8 36 5 30 158 369 62 37

4 15 58 195 206 357 52 15

1 3 9 145 51 221 31 2

1 6 38 276 37 203 43 1

5 17 26 105 37 266 53 70

*See Figure 6 for reference.
100

Table 44. --Estimated percentages of Alaskan-origin pink salmon

by fishery and period of release for which 10 or

more tags were recovered in catch and escapement

sampling in 1982, 1984, and 1985.
101

Table 45. --Estimated season stock compositions based on catchweighted averages of half-monthly percentages of

pink salmon in northern boundary fisheries bound

for the other country, 1982, 1984, and 1985.

Fishery

Percentage from other country

1982 1984 1985

Alaska

Noyes Island 7.2 (1.4)

Dall Island 5.9 (0.7)

Cordova Bay 1.6 (0.3)

Lower Clarence Strait 2.0 (0.3)

Middle Clarence Strait nce

Union Bay

Upper Clarence Strait 3.9 (1.3)

Revillagigedo Channel 8.3 (1.3)

Tree Point 22.2 (3.1)

Canada

Dixon Entrance

Northf

Southf

Langara Island

3x

3Y

3Z

4

5

6

nig

75.0 (3.2)

56.5 (4.0)

55.1 (3.3)

37.5 (3.2)

ne

nt

2.0 (1.0)

10.8 (2.6)

ntc

2.1 (0.5)

nt

nt

nt

6.2 (1.6)

42.5 (3.6)

ni

ni

nt

35.9 (2.6)

49.5 (4.1)

45.1 (4.4)

30.7 (4.4)

28.8 (3.1)

nt

8.2 (4.0)

8.1d(2.5)

1.4 (0.4)

1.5 (1.2)

0.2 (0.1)

12.1 (4.0)

33.4 (4.7)

88.2 (6.8)

55.5 (4.2)

36.8 (3.2)

26.6 (2.3)

59.6 (2.6)

45.9 (2.9)

6.5 (1.1)

6.4 (1.0)

2.3 (1.1)

'Catch-weighted averages were computed for a fishing area provided

reasonably reliable half-month estimates of stock composition (those of

release periods for which at least 10 tagged fish were recovered) covered

at least 75% of the season catch in the area.

b

Standard errors in parentheses account for chance variation in numbers of

recoveries from subsampling catches and escapements but not for errors in

escapement estimates of Alaskan or Canadian stocks.

C

nt - No tagging occurred in this year and area.

d

ne - Less than 75% of the season catch occurred during the periods for

which stock-composition estimates were reasonably reliable.

e

nc - No catch was made in this area.

f

North includes 101-3, 101-4, 101-5, 101-8, and 101-9; South includes

101-6, 101-7, and 101-10. Proportions from tagging in 101-4 were used to

represent North catches, and those from tagging in 101-7 were used for

South catches.

g

ni - Insufficient information on catches by time and area are currently

available to compute an annual value.
102

Table 46. --Effects of different estimates of Alaskan

and Canadian escapements" and Canadian

secondary-tagging mortality on estimated

percentages of Canadian pink salmon in

Alaskan fisheries, 1982, 1984, and 1985.

Escapement Canadian

(millions) tagging

AK Can. mortality Canadian percentage in fishery

1982

Clarence RevillaNoyes Dall Cordova Strait gigedo Tree

Island Island Bay Low up Channel Point

10.5 na

b 0% 7 6 2 2 4 8 22

24.9 na 0% 5 3 1 1 1 7 19

24.9 na 40% 3 2 1 1 1 5 13

8.2 na 0% 7 5 2 2 5 9 22

8.2 na 40% 5 4 1 2 3 7 16

Range 4 4 1 1 4 4 9

13.4 1.9 0% 2 11 2 6 43

16.1 1.5 0% 2 9 2 6 40

9.0 2.3 0% 4 14 3 10 47

16.1 1.5 40% 1 7 1 5 34

Range 3 7 2 5 13

18.3 5.1 0% 8 8 12 0 12 33

19.3 4.0 0% 8 7 110 11 31

12.2 5.8 0% 11 9 220 16 43

19.3 4.0 40% 5 5 111 8 24

Range 6 4 111 8 9

1984

Lower RevillaNoyes Dal1 Clarence gigedo Tree

Island Island Strait Channel Point

1985

Clarence RevillaNoyes Dal1 Strait gigedo Tree

Island Island Low Mid Up Channel Point

'Point estimates and bounds for total escapements appear in this

table, but corresponding values for regional stock groups

(Tables 26, 27) were used in the computations.

b

na - data not available.
103

Table 47.--Effects of different estimates of Alaskan and

Canadian escapements' and Canadian secondarytagging mortality on estimated percentages of

Alaskan pink salmon in Canadian fisheries, 1982,

1984, and 1985.

Escapement Canadian

(millions) tagging

AK Can. mortality Alaskan percentage in fishery

1982

Langara

Island 3X 3Y 4

10.5 nab

24.9 na

24.9 na

8.2 na

8.2 na

Range

13.4 1.9

16.1 1.5

9.0 2.3

16.1 1.5

Range

18.3 5.1

19.3 4.0

12.2 5.8

19.3 4.0

Range

0%

0%

40%

0%

40%

0%

0%

0%

40%

0%

0%

0%

40%

75 57 55 38

79 61 59 44

86 71 71 53

73 56 55 37

81 67 68 46

13 15 16 16

1984

3X 3Y 3Z 4 5

36 50 45 31 29

39 54 49 33 31

31 40 37 26 26

45 61 58 42 36

14 21 21 16 10

1985

Dixon Entrance Langara

North South Island 3X 3Y 3Z 4 5 6

88 56 37 27 60 46 7 6 2

91 58 41 28 62 48 7 7 4

85 51 30 22 51 37 6 5 2

92 64 46 37 68 57 11 11 4

7 13 16 15 17 20 5 6 2

'Point estimates and bounds for total escapements appear in this table,

but corresponding values for regional stock groups (Tables 26, 27) were

used in the computations.

b

na - data not available.

FIGURES

107

Figure l.--International boundary area of southern Southeast Alaska

and northern British Columbia, place names and associated area codes to help identify where returning adult salmon

were tagged, 1982-85.


Figure 4. --ADF&G Southeast Alaska statistical areas 105-108.

Figure 6.--British Columbia subareas l-l through l-5 (Langara Island) and 101-4 through

101-10 of area 1 in Dixon Entrance, 1985.
Figure 7. --British Columbia areas 3 through 5.
Figure 8.-- 1982 and 1983 stock-composition estimates (%) of

sockeye salmon by area and period of release. Best

estimates of escapements were used; and primarytagged entrants in Canada were assumed to

experience the same loss rates in rivers as

secondary-tagged fish. Blanks indicate no

recoveries were made; a bar indicates the stockcomposition estimates are based on fewer than 10

tag recoveries from releases in this fishery and

period.
115

Figure 8. --Continued.
116

Figure 8. --Continued.
117

Figure 8. --Continued.
118

Figure 8. --Continued.
119

Figure 8. --Continued.
Figure 9.--1982, 1984, and 1985 stock-composition estimates (%) of pink salmon by

release area and period. Best estimates of escapements were used, and

primary-tagged entrants to Canadian streams with secondary tagging were

assumed to experience the same recovery rates as secondary-tagged fish.

Blanks indicate no recoveries were made; a bar indicates stock-composition

estimates are based on fewer than 10 tag recoveries from releases in this

fishery and period.
Figure 9. --Continued.

W

Figure 9. --Continued.
Figure 9. --Continued.
Figure 9. --Continued.
Figure 9. --Continued.
Figure 9. --Continued.





133

GLOSSARY

[Italicized words in a definition are also defined in this glossary.]

Bootstrap --A computer-intensive method used to evaluate the

variation in stock-composition estimates caused by

subsampling catches and escapements for tag recovery.

The measure of variation used in the present study was

the standard error of the estimates. Good descriptions

of this general statistical method can be found in Efron

and Tibshirani (1986, 1991).

Catch or fishery recoveries--Primary- and secondary-tagged

salmon recovered during tagging-program sampling of

catches of intervening fisheries.

Confidence interval--A numerical statement consisting of a

lower and upper bound for describing the precision with

which an unknown quantity (such as escapement or the

proportion of a catch comprising fish from a particular

stock) has been determined. Were it possible to

repeatedly replace and draw anew the randomly sampled

observations used to compute the point estimate of the

unknown quantity, a 90% confidence interval would include

the unknown quantity in 90% of the drawings.

Escapement--The maturing adult salmon which survive to return

to spawning systems.

Escapement recoveries--Tagged salmon recovered at weirs, in

riverine fisheries, or during spawning-ground surveys as

part of the tagging-program sampling.

Expand--The total number of tagged fish (T) among a group of N

tagged and untagged fish can be estimated by counting the

number of tagged fish recovered (r) in a random subsample

of size n. The proportion of fish in the subsample which

are tagged, p, equals r/n, and this proportion estimates

the unknown proportion of tagged fish among the N fish,

P, equal to T/N. The estimate of T is obtained as T = Np

= (N/n).r; that is, the number of tagged fish recovered

in the subsample is multiplied by a number greater than

one W/n), or expanded to account for the unexamined

fish.

Intervening fishery--A fishery along the migration route of

primary-tagged salmon as they proceed toward the spawning

grounds of their river of origin. The fishery from which

the tagged fish were released was considered one of the

intervening fisheries.

Petersen tagging experiments--The number of fish (N) in a lake

or on a spawning ground can be estimated by tagging a

known number of fish (M) which then mix with the untagged

members of the population. Subsequently, a sample of C

(Preceding page blank)
134

fish is obtained from the mixture and the number with

tags (R) is determined. If the tagged and untagged fish

are thoroughly mixed at the time the sample is obtained,

the expected proportion of tagged fish in the sample

(R/C) will equal the proportion in the lake (M/N). An

estimate of the number of fish in the lake is obtained by

equating the two proportions and solving for the unknown

number in the lake. The estimate is N=MC/R.

Point estimate--The particular estimate of an unknown quantity

obtained from observed information, in contradistinction

to an interval estimate (e.g., 90% confidence interval)

for the same unknown quantity.

Primary tagging--Salmon were caught and tagged in the coastal

ocean fishing areas of southern Southeast Alaska and

northern British Columbia.

Secondary tagging--Salmon were caught and tagged in terminal

areas in salt water near the outlet streams or rivers to

their spawning grounds,

the rivers themselves.

or were caught and tagged within

Standard error of an estimate--The average of squared

deviations of the estimate of an unknown quantity about

its average value from repeated samplings. The standard

error of an estimate usually must itself be estimated.

An approximate 95% confidence interval for the unknown

quantity is provided by the estimate of the quantity plus

or minus 2 times the estimate of standard error of the

estimate. The bootstrap was used in the present report

to estimate the' standard error of the estimate.

Tagging-program sampling--Known or estimated portions of

commercial catches of salmon and escapements to terminal

areas were subsampled for tag recovery in order to

estimate total numbers of tagged fish present. Such

sampling was conducted by government agencies or their

contracted representatives.

Terminal area--The ocean area and adjacent fresh waters

(outlet stream or river and spawning grounds) within

which the origin of the salmon is presumed known.

Terminal-area entrants--Salmon which have passed through the

commercial fisheries and enter the terminal areas leading

to their spawning ground.

Volunteer tag recovery--Any tag recovered by sampling other

than the tagging-program sampling. Number of fish

examined for tags (among which the tag was found) was not

available. For example, fishermen recovered tags from

fish in their catches but numbers of fish examined were

unreported.
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based on research survey and commercial catch data, 1912-84, 184 p. NTIS No. PB93-167682. 

5	 GUTTORMSEN, M., R. NARITA, J. GHARRETT, G. TROMBLE, and J. BERGER. 1992. Summary 

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