Assessment of Shore Angling Impacts to Kenai River Riparian

75 Pages·2002·0.39 MB·English

Fishery Data Series No. 01-3
Assessment of Shore Angling Impacts to Kenai River
Riparian Habitats, 1998
by
Mary A. King
and
Patricia A. Hansen
March 2001
Alaska Department of Fish and Game Division of Sport Fish

FISHERY DATA SERIES NO. 01-3
ASSESSMENT OF SHORE ANGLING IMPACTS TO KENAI RIVER
RIPARIAN HABITATS, 1998
by

Mary A. King
Division of Sport Fish, Soldotna
and
Patricia A. Hansen
Division of Sport Fish, Research and Technical Services, Anchorage
Alaska Department of Fish and Game
Division of Sport Fish, Research and Technical Services
333 Raspberry Road, Anchorage, Alaska, 99518-1599

March 2001
This investigation was partially financed by the Federal Aid in Sport Fish Restoration Act
(16 U.S.C. 777-777K) under project F-10-14, Job No. H-8.
The Fishery Data Series was established in 1987 for the publication of technically-oriented results for a single
project or group of closely related projects. Fishery Data Series reports are intended for fishery and other technical
professionals. Fishery Data Series reports are available through the Alaska State Library and on the Internet:
http://www.sf.adfg.state.ak.us/statewide/divreports/html/intersearch.cfm This publication has undergone editorial and
peer review.
Mary A. King
Alaska Department of Fish and Game, Division of Sport Fish
43961 Kalifornsky Beach Rd., Suite B, Soldotna, AK 99669-8367, USA
and
Patricia A. Hansen
Alaska Department of Fish and Game, Division of Sport Fish, Research and Technical Services
333 Raspberry Road, Anchorage, AK 99518-1599

This document should be cited as:
King, Mary A. and Patricia A. Hansen. 2001. Assessment of shore angling impacts to Kenai River riparian
habitats during 1998. Alaska Department of Fish and Game, Fishery Data Series No. 01-3, Anchorage.
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TABLE OF CONTENTS
Page
LIST OF TABLES........................................................................................................................................................ii
LIST OF FIGURES.....................................................................................................................................................iii
LIST OF APPENDICES..............................................................................................................................................iv
ABSTRACT..................................................................................................................................................................1
INTRODUCTION........................................................................................................................................................1
Background...................................................................................................................................................................1
Objectives.....................................................................................................................................................................3
METHODS...................................................................................................................................................................4
Distribution of Shore Anglers.......................................................................................................................................4
Bank Loss......................................................................................................................................................................6
Bank Loss and Angler Effort.........................................................................................................................................8
Bank Loss.................................................................................................................................................................9
Angler Effort............................................................................................................................................................9
Bank Loss and Angler Effort..................................................................................................................................11
Trampling and Angler Effort.......................................................................................................................................11
Vegetation Analysis................................................................................................................................................11
Soil Analysis...........................................................................................................................................................12
RESULTS AND DISCUSSION.................................................................................................................................13
Distribution of Shore Anglers.....................................................................................................................................13
Summary................................................................................................................................................................15
Bank Loss....................................................................................................................................................................21
Summary................................................................................................................................................................27
Bank Loss and Angler Effort.......................................................................................................................................27
Summary................................................................................................................................................................28
Trampling and Angler Effort.......................................................................................................................................32
Vegetation Analysis................................................................................................................................................32
Soil Analysis...........................................................................................................................................................37
Summary...............................................................................................................................................................................43
RECOMMENDATIONS............................................................................................................................................43
ACKNOWLEDGMENTS...........................................................................................................................................46
LITERATURE CITED...............................................................................................................................................47
APPENDIX A. KENAI RIVER MANAGEMENT PLANS......................................................................................49
APPENDIX B. OBSERVER MEASUREMENT ERROR ANALYSES...................................................................53
APPENDIX C. SUPPORTING STATISTICS..........................................................................................................57
i
LIST OF TABLES
Table Page
1. Counts of anglers during the recreational fishery for late-run sockeye salmon, by river reach, Kenai
River, 1995-1998..........................................................................................................................................14
2. Angler counts by year, reach, and property ownership, Kenai River, 1995-1998.........................................16
3. Miles of riverbank closed to angling, by river reach, Kenai River, 1996-1998............................................20
4. Changes in angler location and structural use during the sport fishery for late-run sockeye salmon,
Kenai River, 1997-98....................................................................................................................................21
5. Multivariate analyses for effects of angler use, stream meander, boat wake level, and habitat type on
bank positional change, Kenai River, 1998. Analyses used the change in distance from benchmark to
bank edge for all sites, effort and noneffort..................................................................................................26
6. Multivariate analyses for effects of angler effort, stream meander, boat wake level, and habitat type on
bank positional change at angler effort sites, Kenai River, 1998. Analyses used the mean change in
distance to bank edge to determine bank positional change..........................................................................30
7. Multivariate analysis of variance for change in percent cover by cover class from photo imagery
analysis of permanent vegetation plots at habitat survey sites, Kenai River, 1998.......................................34
8. Multivariate analysis of variance for change in percent cover of vegetation, litter, and bare ground, by
habitat type, for permanent vegetation plots at habitat survey sites, Kenai River, 1998...............................34
9. Multivariate analysis of variance for mean change in percent cover by cover class for permanent
vegetation plots at habitat survey sites, Kenai River, prefishery 1997 vs. prefishery 1998..........................37
10. Summary statistics for soil penetrability measurements at 12 habitat survey sites, Kenai River, 1998........39
11. Summary statistics for comparison of soil penetrability measurements at 12 habitat survey sites, Kenai
River, 1997 and 1998....................................................................................................................................41

ii
LIST OF FIGURES
Figure Page
1. Map of Kenai River showing river sections for conducting angler counts, 1998............................................2
2. Schematic of instrument layout for taking bank position measurements, 1998...............................................7
3. Schematic of transects for distance to bank measurements at angler effort sites, 1998................................10
4. Percent of anglers using public and private lands during the sport fishery for late-run sockeye salmon,
Kenai River, 1998.........................................................................................................................................17
5. Angler distribution by their primary fishing location and structural use during the sport fishery for late-
run sockeye salmon, Kenai River, 1998........................................................................................................18
6. Percent of anglers using public and private lands (1996-1998) and percent of public and private
waterfront land (1996), by river reach, Kenai River.....................................................................................19
7. Percent of shore anglers using public lands, Kenai River, 1995-1998..........................................................20
8. Change in bank measurements (June to August) for herbaceous and shrub/herbaceous habitat types,
Kenai River, 1998.........................................................................................................................................22
9. Change in bank measurements (June to August) for disturbed and shrub habitat types, Kenai River,
1998..............................................................................................................................................................23
10. Change in bank measurements (June to August) at tree habitats (right bank), Kenai River, 1998................24
11. Change in bank measurements (June to August) at tree habitats (left bank), Kenai River, 1998..................25
12. Correlation of uncorrected measurements (distance from transit to riverbank) to corrected
measurements (distance from transect through transit to riverbank) by 3-meter intervals............................29
13. Correlation of angler effort to mean change in bank position for 20 herbaceous and 20
shrub/herbaceous habitat sites, Kenai River, 1998.......................................................................................31
14. Bank positional change at selected angler effort sites, Kenai River, 1998....................................................33
15. Relationship of angler effort to change in percent cover (vegetation, litter, and bare ground) for
permanent vegetation plots at herbaceous habitat types, Kenai River, 1998................................................35
16. Relationship of angler effort to change in percent cover (vegetation, litter, and bare ground) for
permanent vegetation plots at shrub/herbaceous habitat types, Kenai River, 1998.......................................36
17. Relationship of angler effort to mean change in percent cover (vegetation, litter, and bare ground) for
permanent vegetation plots at habitat survey sites, Kenai River, prefishery 1997 vs. prefishery 1998.........38
18. Change in mean soil penetrability measurements (psi) at three soil depths for habitat survey sites, Kenai
River, 1998...................................................................................................................................................40
19. Annual change in mean soil penetrability measurements (psi) at three soil depths for habitat survey
sites, Kenai River, prefishery 1997 and prefishery 1998..............................................................................42

iii
LIST OF APPENDICES
Appendix Page
A1. 5 AAC 21.360. Kenai River Late-Run Sockeye Salmon Management Plan................................................50
A2. 5 AAC 56.065. Riparian Habitat Fishery Management Plan.......................................................................51
B1. Observer measurement error analyses...........................................................................................................54
C1. Bank measurements at combined effort and non-effort survey sites, Kenai River, 1998..............................58
C2. Bank measurements at angler effort survey sites, Kenai River, 1998...........................................................63
C3. Summary of angler counts and effort at angler effort sites during the sport fishery for late-run sockeye
salmon, Kenai River, 1998............................................................................................................................65

iv
ABSTRACT
This project focused on the assessment of shore angler impacts to Kenai River riparian habitats. Distribution of
anglers along the banks of the Kenai River during 1998 for river reaches 2-4 was 48.1% on private land and 51.9%
on public land. Land use by anglers in reach 2 (Skilak Lake to Moose River) was approximately even, 49.3% private
and 50.7% public. In reach 3 (Moose River to the Soldotna Bridge), anglers tended to use private land more often,
54.5%. In reach 4 (Soldotna Bridge to Warren Ames Bridge), anglers tended to use more public lands (60.9%). A
comparison of public and private land use by anglers from 1996 to 1998 showed no change in reach 2. A 15.8%
increase in angler use of public lands was detected in reach 3 (χ2 = 196.6, P < 0.01). There was a 3.4% increase in
use of public lands in reach 4 (χ2 = 68.6, P < 0.01). Overall change between 1996 and 1998 showed an 8.5%
increase in use of public lands in reaches 2-4. Of anglers observed in 1998, 93.2% fished from mainland banks. Of
those anglers, 19.3% fished from boardwalks or docks, 55.0% stood in the water, and 25.7% fished while standing
on the bank. Between 1997 and 1998, there was a significant shift of angler use from gravel bars to mainland banks
(1.4%) (χ2 = 126.2, P < 0.01). There was also a significant shift of mainland bank anglers from the use of the bank
to standing on boardwalks or other structures (2.8%) (χ2 = 47.8, P < 0.01).
Of various habitat variables assessed (level of angler use, boat wake level, stream meander, habitat type) none had a
significant effect on the amount of bank erosion at 169 habitat survey sites between June and August 1998. Of the
40 habitat survey sites that had intensified bank measurements and estimates of angler effort, there were no
significant relationships between bank erosion and habitat variables (angler effort, boat wake level, stream meander,
habitat type) between June and August 1998. It would be better to measure bank erosion on a 1-year cycle, with
measurements being taken in June prior to the sport fishery rather than prefishery and postfishery. Shore angler
impacts to the bank may not be fully realized immediately after the sport fishery; weakened banks may experience
calving considerably later than August.
Trampling was assessed by conducting photo imagery analyses of prefishery and postfishery photographs of
permanent vegetation plots. Of the cover classes assessed, there were significant differences detected for effects of
angler effort on percent cover of vegetation (P < 0.01), litter (P < 0.01), and bare ground (P < 0.02). For herbaceous
habitat types, increased angler effort resulted in a significant decrease in mean percent cover of vegetation (P < 0.01)
and a significant increase in mean percent cover of litter (P < 0.01). Increased angler effort at shrub/ herbaceous
habitats also resulted in a significant decrease in mean percent cover of vegetation (P = 0.02) and a significant
increase in mean percent cover of litter (P = 0.06). Herbaceous habitat types were more sensitive to increases in
angler effort and demonstrated a greater mean rate of change for percent cover of vegetation and litter than did
shrub/herbaceous habitat types. For both habitat types, increased angler effort resulted in increased bare ground (P =
0.01). When comparing effects of angler effort to cover class changes between years (June 1997 to June 1998),
there were no significant changes detected, indicating that plant recovery, based upon mean percent coverage, had
occurred. This does not address changes in species diversity.
Penetrability measurements (soil resistance measured with a penetrometer) were used as an indicator of soil
compaction. For 1998, there were no significant changes in penetrability detected at habitat survey sites for
measurements taken at 1 in, 3 in, and 6 in soil depths. However, for between-year comparisons (1997 vs. 1998),
significant change was detected at several sites at the 1 in and 3 in soil depths, and to a much lesser extent at the 6 in
soil depth. All of these sites received some level of angler use; however, without doing soil composition assessment
it is not possible to directly correlate changes in soil penetrability with angler effort at each site.
Key words: Kenai River, shore anglers, riparian habitat, habitat assessment, trampling, angler impacts, bank
erosion, vegetation assessment, soil penetrability, GPS.
INTRODUCTION
BACKGROUND
The Kenai River (Figure 1) supports the largest freshwater sport fishery in Alaska with 247,898
angler days of effort in 1997 (Howe et al. In prep). Fishing effort occurs throughout the
mainstem of the river but primarily occurs over a relatively short time period during June, July,
1
ALASKA
N
K e n a i
River
Kilometers
0 5 10 15
0 5 10
Miles
Moose
Kenai
River to
Anchorage
Cook
Soldotna Hidden
Inlet Lake Kena i River
River
Kenai
Funny Killey
River River
S kilak
Kenai
Lake
Section 1 Russian Lake
River
Section 2
to
Homer Section 3

Figure 1.-Map of Kenai River showing river sections for conducting angler counts, 1998.

and August downstream from Skilak Lake. Targeted species include chinook salmon
Oncorhynchus tshawytscha, coho salmon O. kisutch, sockeye salmon O. nerka, pink salmon O.
gorbuscha, resident rainbow trout O. mykiss and Dolly Varden Salvelinus malma.
Presently, the majority of sport fishing effort on the Kenai River is directed at early- and late-run
chinook salmon and late-run sockeye salmon. Increased interest occurred in the sport fishery
during the mid 1970s when anglers discovered methods for catching chinook salmon while
drifting from powered boats. There was a substantial increase in participation again in the mid
1980s as shore anglers discovered that sockeye salmon could be caught from the turbid waters of
the Kenai River by applying fishing techniques used in the clear waters of the Russian River.
These two discoveries contributed to the ever-increasing popularity of the Kenai River as a sport
fishing destination. Angler days of effort increased from 122,138 in 1977 to 289,165 in 1987
(Nelson 1995). Participation in Kenai River fisheries peaked in 1995 with 377,710 angler days
of effort (Howe et al. 1996).
Most anglers fish for sockeye salmon from riverbanks or while standing in the river along gravel
bars at or near the shoreline. Some sockeye salmon anglers use boats to access desired fishing
locations, but anglers seldom fish from boats. Because sockeye salmon angling is principally a
shorebased fishery, damage to riparian habitat is a major concern to fishery and resource
managers, Kenai River property owners, and stewards of Kenai River resources.
2