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Assessment of land use impacts on shore-spawning kokanee abundance and habitat in Okanagan Lake, British… Wong, Cecilia 1999

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ASSESSMENT OF LAND USE IMPACTS ON SHORE-SPAWNING KOKANEE ABUNDANCE AND HABITAT IN OKANAGAN LAKE, BRITISH COLUMBIA by CECILIA WONG B.Sc, Simon Fraser University, Burnaby, B.C., 1996 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES Resource Management and Environmental Studies We aeCept this thesis as conforming /j to thp required standard THE UNIVERSITY OF BRITISH COLUMBIA May 1999 © Cecilia Wong, 1999 THESIS AUTHORIZATION FORM In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Resource Management and Environmental Studies The University of British Columbia Vancouver, Canada Date ABSTRACT This study examined the possible impact of land use changes on shore-spawning kokanee habitat to explain the decline in Oncorhynchus nerka at Okanagan Lake, British Columbia. Four objectives of the study were: 1.) to characterize spatial and temporal trends in fish abundance using enumeration data provided by the British Columbia Ministry of Environment, Lands and'Parks Regional Fisheries Branch for the period from 1973 and 1997; 2.) to characterize spatial and temporal trends in land use from aerial photographs taken in 1963, 1971, 1981 and 1994-6; 3.) to characterize spatial differences in habitat characteristics from field measurements in the fall of 1997 and spring of 1998; and 4.) to examine associations and causative relationships among land use, habitat features and kokanee abundance. Between 1973 and 1997, the shore-spawning kokanee population decreased by 90.5%. The highest fish counts were reported in 1974 while the lowest were reported for 1993. Within each year, spawning activity was most variable in the southeast quadrant of the lake. Over years, spawning activity also decreased the most in the southeast quadrant. Significance tests revealed that fish enumeration reaches with historically high spawning activity experienced the greatest declines. The current and historical distribution of land use differed between 27 shore segments used for detailed analysis and land use in a 500m buffer zone around the entire lake. Among the 27 study units, forested lands were dominant while sage grasslands dominated the entire lake buffer zone. Changes in land use between 1963 and 1996 were also different. Land use data at the 27 study reaches indicated an increase in urban development and forested lands, and a decrease in agriculture and sage grasslands. Lake-wide data revealed an increase in urban development and a decrease in all other land uses. Despite differences in current and historic land use distributions, temporal trends consistently indicated urban areas increased as agricultural areas decreased. Shallow shoreline areas, shoreline slopes and substrate depths differed significantly among lake quadrants but not study reaches. Shoreline areas were larger in the southeast and southwest quadrants of the lake. Shoreline slopes were steeper and substrate depths were greater in the northwest quadrant. Steeper ii shoreline slopes, greater substrate depths and more angular substrate characterized enumeration reaches with higher current spawning activity. Shoreline areas with gradual slopes, more shallow substrate depths and less angular substrate characterized areas with a higher density of buildings and docks along the shoreline and larger areas of agriculture and sage grasslands within the 500 m buffer zone. These observations suggest that habitat features may facilitate interactions between land use and spawning activity. Interactions between fish abundance and land use including the area of development, agriculture and sage grasslands were demonstrated, however the associations were weak. Dock density was a better predictor of reduced spawning activity than the areal index of land use adjacent to the lakeshore. The current study examines only the shore-spawning stage of the kokanee life history. Other shore-related stages that may be impacted by habitat changes associated with land use likely include egg incubation, alevin maturation and fry emergence stages. Additional studies are recommended to examine the relative contributions of these stages to overall fish abundance. At the same time, it is recognized that some shoreline issues may already be addressed with conscientious water level management and control of lakeshore development. iii TABLE OF CONTENTS ABSTRACT List of Tables List of Figures List of Abbreviations and Symbols Acknowledgements CHAPTER 1 - INTRODUCTION 1.1 Research Goals 1.2 Research Obj ectives 1.3 Basic Research Assumptions CHAPTER 2 GENERAL DESCRIPTION OF THE STUDY AREA 2.1 Location 2.2 Climate 2.3 Biogeoclimatic Zones 2.4 Hydrology 1 2.5 Limnology 1 CHAPTER 3 - STUDY SPECIES KOKANEE 3.1 Distribution 3.2 Life History Strategies of Nerkids 3.3 Biology 3.4 Spawning Habitat 3.5 Ecology CHAPTER 4 - STUDY SPECIES- HOMO SAPIENS 4.1 Historical Development 4.2 Current Trends CHAPTER 5 - A CASE FOR INTERACTIONS 5.1 Fish Abundance and Fish Habitat 5.1.1 The Concept of Habitat Change 5.1.2 Mechanisms for Correla tions 5.2 Land Use and Habitat Characteristics 5.2.1 Mechanisms for Correlations 5.3 Fish Abundance and Land Use Activities 5.3.1 Mechanisms for Correla tions iv CHAPTER 6 -FISH ABUNDANCE STUDY 30 6.1 Methods and Materials 30 6.1.1 Source of Data 30 6.1.2 Analyses Performed 31 6.2 Results 32 6.2.1 Review of Fish Enumeration Data 32 6.2.2 Analyses of Spatial and Temporal Trends 34 6.2.3 Classification and Selection of Reaches for Land Use and Habitat Studies 38 6.3 Discussion 39 CHAPTER 7 - LAND USE STUDY 41 7.1 Methods and Materials 41 7.1.1 Source of Data 41 7.1.2 Analyses Performed 41 7.2 Results 44 7.2.1 Review of Land Classification Data 44 7.2.2 Analyses of Spatial and Temporal Trends 44 7.3 Discussion 51 CHAPTER 8 - FISH HABITAT USE STUDY 53 8.1 Methods and Materials 53 8.1.1 Source of Ddata 53 8.1.2 Analyses Performed 54 8.2 Results 54 8.2.1 Habitat Trends 54 8.2.2 Correlations among Upland Characteristics 61 8.3 Discussion 62 CHAPTER 9 - INTERACTIONS 64 9.1 Fish Abundance and Fish Habitat 64 9.1.1 Methods- Analyses Performed 64 9.1.2 Results of Analyses 65 9.1.3 Discussion 68 9.2 Land Use Activities and Fish Habitat 70 9.2.1 Methods- Analyses Performed 70 9.2.2 Results of Analyses 70 9.2.3 Discussion 73 9.3 Fish Abundance and Land Use Activities 75 9.3.1 Methods- Aanalyses Performed 75 9.3.2 Results of Analyses 76 9.3.3 Discussion 84 9.4 Effects of Buffer Zone Width 86 9.4.1 Methods- Analyses Performed 86 9.4.2 Results- Correlations among Variables 87 9.4.3 Discussion 88 v CHAPTER 10 - CONCLUSIONS .' 89 10.1 Summary of Trends 89 10.1.1 Trends in Fish Abundance 89 10.1.2 Trends in Land Use/Cover 89 10.1.3 Habitat Comparison 90 10.2 Summary of Interactions 90 10.2.1 Fish Abundance and Habitat Characteristics 90 10.2.2 Land Use and Habitat Characteristics 91 10.2.3 Fish Abundance and Land Use 91 10.3 Recommendations 91 CHAPTER 11 - REFERENCES 94 APPENDIX A- Data Summaries for Annual Peak Fish Abundance per Reach 103 APPENDIX B- Data Summaries for Level 1 Land Use and Cover Classifications per Reach 107 APPENDIX C- General Checklist for Inventory of Shoreline Characteristics at each Reach Ill vi LIST OF TABLES Table 1- Approximate Annual Water Budget for Okanagan Lake 11 Table 2- Factors that Affect the Abundance of Fish in Temperate Lakes and Reservoirs 24 Table 3-General Sampling Route and Level of Sampling 33 Table 4- Spearman Rank Correlation Results for Historical Spawning Activi ty vs. Declines in Fish #s ... 37 Table 5- Enumeration Reaches Selected for Further Land Use and Habitat Studies 38 Table 6-Land Use and Land Cover Classification for A i r Photo Interpretation 42 Table 7- Study Units with Development 500 m from Shoreline in 1963 and 1996 46 Table 8- Study Units with Agriculture 500 m from Shoreline in 1963 and 1996 49 Table 9- Study Units with Sage Grasslands 500 m from Shoreline in 1963 and 1996 49 Table 10- Summary Table of Habitat Characteristics at 27 Study Reaches 55 Table 11- Kruskal-Wallis Rank Test Results for Differences in Substrate Size Variables Among Substrate Depths 58 Table 12- Habitat Characteristics for Comparison with Fish Abundance and Land Use Indices 62 Table 13- Variables Compared for Relationships between Fish Abundance and Habitat 64 Table 14- Classification of Fish Abundance per Reach for Significance Testing 65 Table 15- Significant Spearman Correlation Coefficients between Fish#s & Habitat Characteristics 65 Table 16- Variables Compared for Relationships between Land Use Activities and Habitat Indices 70 Table 17- Significant Spearman Rank Coefficients between Land Use and Habitat Characteristics 71 Table 18- Significance between Habitat Features and the Presence/Absence of Specific Land Uses 72 Table 19- Variables Examined for Relationships between Fish Abundance and Land Use Activities 75 Table 20- Significant (oc< 0.05) and Strong (|rho|> 0.50) Spearman Rank Correlations for Fish Abundance vs. Land Use Indices 77 Table 21- Significance of Differences in Fish Abundance with Presence/ Absence of Land Uses 78 Table 22- Significant Differences in Fish Abundance with Changes in Land Uses 80 Table 23- Variables Compared for Relationships between Fish Abundance and Habitat 87 Table 24- Significant and Strong Spearman Correlation Coefficients among Fish Abundance, Habitat Characteristics and Development 87 vi i LIST OF FIGURES Figure 1- Population Density in British Columbia in 1991 1 Figure 2- Number of Residents vs. Number of Kokanee from 1976 to 1996 2 Figure 3- Research Hypothesis 3 Figure 4- Location of Okanagan Basin within British Columbia 6 Figure 5- Study Area 7 Figure 6- Mean Monthly Temperatures from 1961-1990 8 Figure 7- Mean Monthly Precipitation from 1961-1990 8 Figure 8- Population Change from 1971 to 1996 20 Figure 9- Industry Distribution of Work Force in the Okanagan and B C 21 Figure 10- Map of Okanagan Lake and Study Sites 31 Figure 11- Correlogram of Fish Abundance 34 Figure 12- Current Fish Abundance among Quadrants (a) and Reaches (b) of the Lake 35 Figure 13- Historical Fish Abundance among Quadrants (a) and Reaches (b) of the Lake 35 Figure 14- Temporal Comparison of Fish Abundance through the Decades (a) and among Years (b) 36 Figure 15- Comparison of Declines in Fish Abundance among Quadrants (a) and Reaches (b) 37 Figure 16- Strong Negative Correlation between Current Declines in Spawning Activity and Historical Fish Abundance 38 Figure 17- Sites Selected for Detailed Land Use and Fish Habitat Studies 39 Figure 18- Dominant Land Use Patterns around Okanagan Lake in 1963 and 1996 45 Figure 19- Dominant Land Use and Cover Characteristics at the 27 Study Units to a Distance of 500 m from the Shoreline (a) and Directly Along the Shoreline (b) 46 Figure 20- Spatial Distribution of Change in Development between 1963 and 1996 47 Figure 21- Positive Correlation between Shoreline Reaches Developed in 1963 and 1996 48 Figure 22- Increases in Shoreline Development between 1963 and 1996 Represented by Increases in the # of Nearshore Buildings (a) and Docks (b) per km of Shoreline 48 Figure 23- Spatial Distribution of Change in Agriculture between 1963 and 1996 49 Figure 24- Spatial Distribution of Change in Sage Grasslands between 1963 and 1996 50 vi i i Figure 25- Spatial Distribution of Forested Lands (a) and Change in Forested Lands (b) between 1963 and 1996 51 Figure 26- Comparison of Lakewide Data to Data Pooled for all Study Reaches 500 m from Shoreline... 52 Figure 27- Spatial Comparison of Shoreline Areas as a Function of Water Depth 56 Figure 28- Spatial Comparison of Shoreline Slopes Among Quadrants 56 Figure 29- Spatial Comparison of Substrate Depths Among Quadrants 57 Figure 30- Comparison of Substrate Lengths Among Study Reaches 57 Figure 31- Comparison o f Substrate Lengths as a Function o f Substrate Depths 58 Figure 32- Comparison of Substrate Mass and Substrate Volume as Functions of Substrate Depths 59 Figure 33- Spatial Comparison of Differences in Angularity Among Quadrants and Reaches 59 Figure 34- Comparison of Substrate Angularity with Substrate Depth 60 Figure 35- Spatial Comparison of Dissolved Oxygen Concentrations Among Study Reaches 60 Figure 36- Spatial Comparison of Periphyton Cover on Substrate Among Study Reaches 61 Figure 37- Differences in Substrate Depth (a) and Angularity (b) between Enumeration & Control Reaches 66 Figure 38- Differences in Substrate Depth (a) and Angularity (b) with Varying Levels of Fish Abundance 67 Figure 39- Differences in Shoreline Slope (a) and Angularity (b) between Enumeration Reaches with Significant vs. Insignificant Changes 67 Figure 40- Interactions between Fish Abundance and Habitat Characteristics 68 Figure 41- Interactions between Dock Density and Shoreline Slope (a) and Dock Density and Substrate Angularity (b) 71 Figure 42- Shoreline Slope as a Function of the Presence/ Absence of Nearshore Buildings along the Shoreline (a), Docks along the Shoreline (b) and Agriculture in the Study Area (c) 72 Figure 43- Substrate Angularity as a Function of the Presence/ Absence of Nearshore Buildings (a) and Docks (b) along the Shoreline, and Agriculture in the Study Area (c) 73 Figure 44- Interactions between Land Use and Habitat Characteristics 74 Figure 45- Current Fish Abundance vs. Forested Lands 77 Figure 46- Changes in Fish Abundance vs. Forested Lands 78 Figure 47- Current Fish Abundance as a Function of the Presence/ Absence of Development 79 ix Figure 48- Current Fish Abundance as a Function of the Presence/ Absence of Nearshore Buildings (a) and Docks (b) 79 Figure 49- Current Fish Abundance as a Function of the Presence/ Absence of Agriculture (a) and Sage Grasslands (b) 79 Figure 50- Current Fish Abundance vs. Changes in Development (a) and Agriculture (b) between 1971-96 80 Figure 51- Current Fish Abundance vs. Changes in Sage Grasslands (a) and Forested Lands (b) between 1971 and 96 81 Figure 52- Comparison of Current Areas of Sage Grasslands Associated with High, Medium, L o w and Very L o w Levels of Current Fish Abundance 82 Figure 53- Comparison of Historical Areas of Agriculture (a), Sage Grasslands (b) and Forested Lands (c) Associated with High, Medium, L o w and Very L o w Levels of Current Fish Abundance 82 Figure 54- Comparison of Current Land Use Characteristics at Enumeration Reaches with Significant Declines in Fish Abundance (a) vs. Reaches where Declines were Insignificant (b) 83 Figure 55- Comparison of Historical Land Use Characteristics at Enumeration Reaches with Significant Declines in Fish Abundance (a) vs. Reaches where Declines were Insignificant (b) 84 Figure 56- Interactions between Fish Abundance and Land Use Characteristics 85 Figure 57- Interactions between Fish Abundance and Land Use Facilitated by Habitat Characteristics.... 86 x LIST OF ABBREVIATIONS AND SYMBOLS M E L P Ministry of Environment, Lands and Parks S E southeast N E northeast N W northwest SW southwest B G Bunchgrass biogeoclimatic zone PP Ponderosa Pine biogeoclimatic zone IDF Interior Douglas Fir biogeoclimatic zone GIS Geographic Information System D E V Urban Development A G R Agriculture S A G Sage Grasslands F O R Forested Lands m metres cm centimetres z lake water depth @ at °C degrees Celsius D O dissolved oxygen A N G angularity S P H sphericity xi ACKNOWLEDGEMENTS The B . C . Ministry of Environment, Lands and Parks through the Okanagan Lake Action Plan provided funding for this project. Furthermore, the following have provided invaluable data, insights or personal expertise for which I am very grateful: Dave Smith, Bruce Shepherd, Jim Bryan, Dale Sebastian and Ken Ashley, B . C . Ministry of Environment, Lands and Parks; Tom Northcote, University of British Columbia; and Peter D i l l , Okanagan University College. Assistance for field sampling was provided by Carrie Dean, University of British Columbia; Lisa Mose and K i m Rondeau, Okanagan University College; Laurie McEachern and Graham Young, Dave Smith and Bruce Shepherd, B . C . Ministry of Environment, Lands and Parks. I would like to thank my supervisor, Hans Schreier, for his guidance and his time—I realize it's difficult to adjust to this time zone when exciting work takes you around the globe. I would also like to thank members of my thesis committee for their wisdom, inspiration, tenacity and tolerance of my email questions and requests—thank you Dave Smith, Tom Northcote and K e n Hal l ! Thank you Sandy Brown for your words of advice and pitching in! Thank you Les Lavkulich and Nancy Dick—you always seem to have a smile and answers. Thank you K i r k Johnstone, Col in Gray, Fred Mah, Bev McNaughton and Andrea Ryan for checking to see how things are going and caring. To my mom—thank you for your love, strength and confidence in me, for being such a great role model, and for making sure my fridge works and is fully stocked with the four food groups. Finally, to Reg i— thank you for being my ear and for believing in me, for love, laughter and your endless support in so many ways. I can never thank you enough! x i i CHAPTER 1 - INTRODUCTION Okanagan Lake is situated in the warm, dry southern interior of British Columbia, one of the fastest growing regions in the province with respect to resident and tourist populations. Oncorhynchus nerka was an historically abundant species in the lake, however after decades of change around the lakeshore, kokanee suffered dramatic declines. The following study examines relationships between human activities demonstrated by land use, and shore-spawning kokanee, an ecologically and socio-economically significant species in the basin. Census data for B . C . reveal that human population growth within the Okanagan Valley is third only to the Lower Mainland and the southeast coast of Vancouver Island (Statistics Canada, 1996). Associated with this growth are expanding populations (Figure 1; Statistics Canada, 1996) and associated activities that can shift the biophysical nature of the valley and the aquatic environment immediately adjacent to these areas. Human activities around Okanagan Lake are particularly evident: large areas of agriculture, growing urban centres, and lakeshore cottages, motels and docks proliferate along the shoreline. Southeast L o w e r Mainland Vancouver Island Figure 1- Population Density in British Columbia in 1991 (1 dot= 25 persons; Statistics Canada, 1996) 1 Two physiologically landlocked stocks of O. nerka in Okanagan Lake are stream spawning and shore-spawning kokanee. These fish are identical in external morphology throughout their life history until the time of spawning (Di l l , 1996). A behavioral distinction between the two strains arises from their preference in spawning habitat. Concurrent with increases in human settlement and shoreline development was a striking decline in both stream and shore-spawning kokanee abundance (Figure 2). Changes were so significant that in March, 1995, the kokanee sport fishery in Okanagan Lake was closed in efforts to conserve fish stocks. 300 200 o o o CD o c ro "O c X3 < CO 0) c ro o CD L_ C CD O i_ o 'ro" o 2 ° *= o c CO -q '<a CO CC Enumeration Year Figure 2- Number of Residents vs. Number of Kokanee from 1976 to 1996 Note: Actual conditions in Okanagan Lake are likely more severe than this figure portrays. Fish abundance from 1971 to 1976 was excluded from the graph, however population sizes during these earlier years were significantly larger than those for 1976. Abundance for 1980-82 and 1984 were excluded from the graph because their counts were not delineated by reach for land use and habitat analyses. Furthermore, human population numbers in the lake are likely higher because only resident populations from urban centres are presented. Resident populations from more unorganized urban areas are not presented. Also , in recent years, seasonal tourist populations have been growing for events around the lake. These numbers are also not presented. (Source: Statistics Canada, 1996; B . C . Ministry o f Environment, Lands and Parks, 1996) A technical workshop was held June 1996 in Kelowna, B . C . to address the significant decline in Okanagan Lake kokanee abundance. Several hypotheses were proposed to explain the reductions. These included: "...degradation and/or loss of ...spawning habitat...increased angling pressure, decreased point source nutrient loading from wastewater treatment plants; introduction of exotic species (eg. mysid shrimp, coarse fish), reduction of kokanee shore-spawning habitat due to timing 2 and extent of seasonal drawdown and shoreline habitat alteration, urban runoff, and competition between hatchery and native stocks of kokanee" (Ashley and Shepherd 1996). The Okanagan Lake Action Plan was established to "gain a better understanding of whole lake biological relationships, define limiting factors, and identify and implement remedial measures" (Ashley et al., 1998) for restoring both stream and shore-spawning kokanee populations. 1.1 RESEARCH GOALS This current study attempts to characterize the relationship between habitat conditions and shore-spawning kokanee abundance, and determine the effect of changes in land use activities on shore-spawning habitat. The research hypothesis is that changes in land use and habitat conditions influence kokanee abundance (Figure 3). Fish Abundance Figure 3- Research Hypothesis 1.2 RESEARCH OBJECTIVES The study has the following objectives: a) To examine historical changes in the spatial distribution of shore-spawning kokanee; b) To examine historical changes in land use and land cover; c) To gather current data on the availability of habitat preferred by shore-spawning kokanee; and d) To examine associations and possibly causative relationships among fish abundance, land characteristics and fish habitat. 3 1.3 BASIC R E S E A R C H ASSUMPTIONS To proceed from characterizing trends in fish abundance (objective a), land use (objective b), and fish habitat (objective c) to a consideration of interactions among the variables (objective d), the following assumptions were made: • Assumptions of Study Interactions between Fish Abundance and Habitat Use It was assumed that if favourable spawning habitat was available, kokanee would use this habitat and the more favourable a suite of characteristics at a particular site, the more fish would spawn at the site. The habitat characteristics considered in the study were also assumed to be of importance to the fish. Moreover, it was assumed that there are currently sufficient numbers of fish to randomly distribute among habitats ranging in their suitability. Only one year of habitat data was collected in the course of this study, thus only the spatial distribution of spawning fish to habitat characteristics was possible. The study distinguished habitat characteristics at beaches associated with greater fish abundance vs. those with lower fish abundance. It was assumed that fish escapement was affected more so by spawning habitat availability than any other factor. It was further assumed that while other factors may affect the fitness of kokanee throughout their life history, these produce little "noise" that confound interactions between fish habitat and shore-spawner abundance. Additional investigations considering some of these factors are now being conducted under the Okanagan Lake Action Plan. The current study did not address the relative significance of these factors nor integrate the results of these projects into its conclusions as the data were unavailable. • Assumptions of Study Interactions between Land Use and Habitat Characteristics A large number of potential point and non-point sources of impact between land use activities and habitat characteristics exist, and regional differences in climate, hydrology and geology can exacerbate or mitigate these interactions. It was assumed that an areal index of land use activities adjacent to shore-spawning habitat would be a comprehensive and sensitive indicator of variations in habitat 4 characteristics to be expected from spatial differences in land use when these site specific variables are considered. Again, only one year of habitat data was collected in the course o f this study thus, only the spatial distribution o f land use activities to habitat characteristics was possible. The study distinguished habitat characteristics adjacent to land with higher levels of human influence such as development and agriculture vs. those with lower levels such as forested lands and sage grasslands. • Assumptions of Study Interactions between Fish Abundance and Land Use If associations exist between fish abundance and shore-spawning habitat characteristics, and land use and the same or related habitat characteristics, there should exist a relationship between kokanee escapement and land use over time. If a common set of habitat indices varies with fish abundance and land use features, interactions between fish abundance and land use may be facilitated through interactions o f each with shoreline habitat. Although historical data on habitat characteristics was unavailable, it was assumed that habitat indices have changed over time. 5 CHAPTER 2 - GENERAL DESCRIPTION OF THE STUDY AREA The following chapter describes the location of Okanagan Lake and the geographic extent of the study area. Climate, biogeoclimatic, hydrological and limnological characteristics of Okanagan Lake are also briefly described to highlight unique characteristics of the study area as they relate to kokanee shore-spawning habitat or land use. 2.1 LOCATION The Okanagan Basin is situated in the south interior plateau area of British Columbia (Figure 4). Its central drainage system consists of a chain of lakes connected by the Okanagan River, which flows south from Okanagan Lake and across the international border. The basin is bound in the west by the Similkameen River Basin, the east by the Kettle River Basin, the north by the Shuswap River Basin, and the south by the international boundary. Okanagan Lake is the largest lake in the chain. Figure 4- Location of Okanagan Basin within British Columbia (OKAN= Okanagan Basin, SIML= Similkameen River Basin, KETL= Kettle River Basin, USHU= Shuswap River Basin; BC MELP, 1998) The study examines all shoreline reaches of Okanagan Lake where shore-spawning kokanee data were available at the time of this study. These include the east side of the lake from Squally Point to Vernon Arm and the west side of the lake from Vernon Arm to Gellatly. Shoreline reaches near Okanagan 6 Lake Park, Sun Oka Beach and Naramata Creek were also examined and terrestrial areas 500 m inland from the lakeshore considered (Figure 5). Sun-Oka Beach Summerland Y "V ^ V V p Naramata Penticton Figure 5- Study Area 2.2 CLIMATE Riparian vegetation and associated fauna that interact with lacustrine resources are strongly influenced by the long-term temperature and precipitation patterns of a region (Meidinger and Pojar, 1991). Climate also influences how favourable regions are to various anthropogenic land uses such as seasonal tourism and fruit growing, and the intensity of demands on local water resources. Hot dry summers and cool cloudy winters characterize the climate of the Okanagan Basin. Throughout the year, temperatures range from short winters between 0 and 5 degrees Celsius to summer highs between 15 and over 20 degrees Celsius (Figure 6a; Environment Canada, 1993). Among sites around the lake, the median temperature was highest at Winfield and the range was greatest near Kelowna (Figure 6b). Precipitation occurred bimodally at each site: snowfall characterized the winter peak; rainfall characterized a second peak from late spring to summer (Figure 7a). The driest seasons were early spring 7 (March and Apri l) and early fall (September and October). Among sites, precipitation increased with elevation and latitudes (Figure 7b). Figure 6- Mean Monthly Temperatures from 1961-1990 (Data in brackets represent elevations; Environment Canada, 1993). a Figure 7- Mean Monthly Precipitation from 1961-1990 (Data in brackets represent elevations; Environment Canada, 1993). 8 2.3 BIOGEOCLIMATIC ZONES The topography, climate and geology of the region interact to produce three biogeoclimatic zones within the study area: the bunchgrass (BG) zone, the ponderosa pine (PP) zone and the interior douglas fir (IDF) zone (Meidinger and Pojar, 1991). They also yield unique systems for agricultural land uses. The B G zone occupies a portion of the study area from Summerland through Penticton. Bunchgrasses (Meidinger and Pojar, 1991) characterize climax conditions in the B G zone. From the Valley bottom to 700 m, the ecosystem is characterized by very hot dry climate and brown soils that support sparsely distributed bluebunch wheatgrass, big sagebrush and many lichen species. Temperature sensitive crops such as peaches, apricots and grapes also favor these brown soils (Canada-B.C. Consultative Board, 1974a; Kerr et al., 1993). Between 700 m and 1,000 m from Summerland to Oyama, the climate is slightly cooler and moister, and dark brown soils support more closely spaced bluebunch wheatgrass, a higher diversity of forbs and a lower diversity of lichens. With irrigation, dark brown soils can also produce large varieties o f fruits and vegetables (Kerr et al., 1985). The PP zone occurs south of Vernon through Penticton at low elevations from 335 to 900 m. In summer months, the PP zone is the driest and wannest forested zone in British Columbia where it is dominated by a ponderosa pine canopy and a bluebunch wheatgrass understory (Meidinger and Pojar, 1991). Other tree species supported by the dark brown soils are douglas fir (Pseudotsuga menziesif), trembling aspen (Populus temuloides), water birch (Betula occidentalis) and black cottonwood (Populus balsamifera ssp. trichocarpa). Forests are interspersed with grasslands of bluebunch wheatgrass and big sagebrush (Meidinger and Pojar, 1991). The IDF zone spans from Vernon through Penticton at elevations from 600 m to 1,450 m just above the PP zone (Meidinger and Pojar, 1991). Its cooler and moister climate and dark brown to dark grey soils distinguish it from the PP and B G zones. These conditions support climax pure douglas fir stands which may have an open canopy where historical ground fires occurred and mature trees with thick bark was favoured. In mixed stands, douglas firs share the canopy with lodgepole pine (Pinus contorta), ponderosa 9 pine, and trembling aspen. Stands share the landscape with areas of bunchgrasses and snowberry (Symphoricarpos albus) when they are in good to excellent condition, and areas of pinegrasses (Calamagrostis rubescens) and yarrow (Achillea millefolium) when subjected to grazing pressure. When located on level or gently sloping land they can also support orchard crops where natural drainage is good, and forage crops, gardens and berries where soils are wetter (Canada-B.C. Consultative Board, 1974a). 2.4 HYDROLOGY Hydrology and water use management were studied extensively by the Canada-BC Consultative Board (1974), the Okanagan Basin Implementation Agreement Public Task Force (November 1980), Ward (1998) and Shepherd and Sebastian (1998). Consequently, the following section will highlight activities affecting the water budget for the lake and refer to these sources for more detailed information about water quantity issues and management. Table 1 is from Ward, 1998 which summarizes the available data on evaporation, precipitation, water surface levels, stream flow on Okanagan River, stream flow in the main tributaries of Okanagan Lake, and current water licences. From the table, it appears that the largest contribution to the lake is from runoff, primarily due to snowmelt from April to June (Canada- B.C. Okanagan Basin Plan, 1974). The annual water volume that runoff accounts for is approximately equal to the sum of volumes removed by evaporation from the lake and outflow to the Okanagan River at Penticton (Table 1). It is important to note that the net runoff from the lake basin was estimated in 1974 when land uses in the basin were different. Recent changes in agriculture and urban development are likely to cause changes in surface and subsurface runoff to the lake. 10 Table 1- Approximate Annual Water Budget for Okanagan Lake Note: The annual volumes do not balance without consideration of the error estimates (from Ward, 1998) Description Annual Error Estimated Record Reference Volume (Mm3) (Mm3) Period + Net runoff on the 780 +1-3,9 1921-70 Canada- B.C. Okanagan Basin lake basin Agreement, 1974 + Contribution from 100 +/- 15 1931-60 Assuming annual precipitation on precipitation on the lake of 315 mm +/- 48 mm lake - Evaporation from 330 +/-50 1921-70 Canada- B.C. Okanagan lake Agreement, 1974 - Abstraction 96 +/- 14 1997 Record B.C. Government Water Rights Information System + Return flow from 62 +1-9 Return flow assumed as 65% of abstraction the total diversion - Outflow at 470 +/- 24 1921 to H Y D A T CD R O M Penticton Present Water management of Okanagan Lake aims primarily to protect from floods and droughts, and for consumptive water uses by municipal, agricultural and industrial water users. Control structures were installed at the Penticton outlet of the lake in 1912 (Shepherd and Sebastian, 1998). Shepherd and Sebastian (1998) estimate that prior to 1912, water levels varied naturally by a maximum of 2.7 m. The dam was rebuilt in 1953 to accommodate changes in water levels over a 4.2 m range (Shepherd and Sebastian, 1998). Guidelines for the operation of the lake were specified in the Comprehensive Framework Plan of the Canada-BC Consultative Board (1974) and modified in the Final Report of the Okanagan Basin Implementation Agreement Public Task Force (November 1980). Specifically, water levels should not fluctuate more than 1.22 m over the course of a year. To achieve this goal, water levels are held relatively high and constant from October 15 to February 1. To create storage for runoff events during freshet the following spring and summer, water is withdrawn after February 1 (Ward, 1998). Water management for human activities comes at the cost of kokanee incubation and emergence habitat. Spawning occurs in water as shallow as 0.25-0.5 m (Dill, 1998) in late October when the Okanagan Lake is reaching its highest levels. Because water withdrawals (allowable to 1.22 m) begin prior to fry emergence, there exists a very real potential for fry to be stranded, alevins to be frozen or eggs to be dried through the late winter or early spring months. The effects of regulating lake levels on shore-spawning kokanee stocks is currently being studied by Shepherd and Sebastian (1998) and Ward (1998). 11 Although lake fluctuation was not a major focus of this study, it is becoming evident that this might have a significant impact on kokanee reproductive success. 2.5 LIMNOLOGY Extensive studies on Okanagan Lake limnology have been conducted by Clemens et al. (1939); the Canada-BC Consultative Board (1974); Patalas and Salki, (1973); Stockner and Northcote (1974); Bryan (1990); Bryan (1996); and Nordin (1996). Studies are currently being conducted by Nordin (1998), McEachern (1998) and Thompson and Kuzyk (1998). Consequently, the following section wi l l highlight limnological features that are discussed in the current study and refer to these sources for more detailed information about Okanagan Lake limnology. Okanagan Lake is dimictic, having two circulation periods per year (Canada-B.C. Consultative Board, 1974b). McEachern (1998) reported that from July through October 1996, thermal stratification was indicated by a hypolimnion occurring at 20 m. The hypolimnetic depth decreased to 45 m as mixing took place through November (McEachern, 1998). Water temperatures consistently and simultaneously measured at kokanee shore-spawning reaches from October, when kokanee are spawning, to Apr i l , when fry emerge from the gravel, were not available. Hypolimnetic (25 m and 50 m) dissolved oxygen concentrations were consistently above 8.5 mg/L in September, 1969 and August, 1971 at all sites except the northernmost site, Armstrong A r m , where dissolved oxygen dropped to 6.4 mg/L (Patalas and Salki, 1973). From 1970-1988, concentrations were consistently lower in the north end of the lake (Bryan, 1990). More recent measures by McEachern (1998) were similar, with dissolved oxygen concentrations above 6 mg/L at all sites except Armstrong Arm. It is expected that littoral dissolved oxygen concentrations should be higher than the limnetic concentrations described because of the influence of wave action on shallow areas of the shoreline and oxygen production by littoral macrophytes. Higher gas solubility through cold winter months may also produce higher dissolved oxygen concentrations when eggs and alevins are developing in shore areas. Like water temperatures, consistent shoreline measures of dissolved oxygen concentrations were unavailable. 12 Macrozooplankton species were similar among samples collected in 1969, 1971 and 1996. However, the relative abundance of cladocerans has changed over time: Bosmina and Diaphanasoma have replaced Daphnia cladocerans as the dominant cladoceran (Nordin, 1996). This may be of concern since Daphnia cladocerans are a preferred food item of both kokanee and the crustacean Mysis relicta. Since the introduction of Mysis into Okanagan Lake in 1966, the abundance of Mysis has increased from 0 to 250 per square metre (Shepherd, 1996; Lasenby, 1996; Nordin, 1996). Periphyton growth was observed to increase from the 1960s to early 1970 (Stockner and Northcote, 1974). Seasonal patterns of growth were characterized by a bloom of diatoms in M a y to early June, a smaller pulse of green algae or cyanobacteria in late August, followed by another bloom of diatoms in the fall (Stockner and Northcote, 1974; Canada-BC Consultative Board, 1974a). While the study by Stockner and Northcote identified the significance of periphyton growth on the reproductive success of Okanagan Lake shore-spawning kokanee, no recent studies have been published on the issue. However, the Regional Waste Management Branch of the Ministry o f Environment, Lands and Parks is currently conducting an extensive study on shoreline periphyton. A survey of fish species was conducted in 1971 (Canada-BC Consultative Board, 1974c). Based on the methods of sampling, kokanee dominated all species as the most abundant fish, followed by peamouth chub and northern squawfish. The least abundant fish were slimy sculpins, leopard dace and redside shiner (Canada-BC Consultative Board, 1974c). N o formal study has been conducted since this time. Fish species recorded since 1974 include yellow perch, lake trout, brook trout, pygmy whitefish, pumpkinseed, and Umatilla dace (Smith, pers. comm., 1999). 13 CHAPTER 3 - STUDY SPECIES- KOKANEE This chapter will describe the distribution and distinguishing features of kokanee, the biology and ecology of the fish in relation to its life cycle, and the spawning habitat requirements of Okanagan Lake shore-spawning kokanee. 3.1 DISTRIBUTION The distribution of Oncorhynchus nerka extends from Pacific drainages in North America to north eastern Asia (Nelson, 1968). In North America, they are found naturally from the Klamath River, California to Point Hope, Alaska, and in Asia from northern Hokkaido, Japan to Anadyr River, Russia (Oregon Department of Fish and Wildlife, 1997; BC Adventures, 1997; McPhail and Lindsey, 1970; Foerster, 1968; Nelson, 1968). Over most of this species range, kokanee are found occurring both sympatrically with sockeye and in lakes to which anadromous fish no longer have access, including both naturally and artificially blocked lakes. Within the Okanagan Basin, kokanee are found throughout the main valley lakes. Okanagan, Kalamalka and Wood Lakes are unique in that they support both stream and shore-spawning populations of kokanee salmon. 3.2 LIFE HISTORY STRATEGIES OF NERKIDS There are two forms of nonanadromous nerkids: residual sockeye and kokanee (Burgner, 1991; Murray et al., 1989; Ricker, 1938). Residual sockeye are in part, the progeny of anadromous fish while kokanee are the progeny of nonanadromous fish for several generations, and there is no clear connection between kokanee and sockeye (Ricker, 1938). While residual sockeye are usually males that do not develop strong secondary sex characteristics during spawning, kokanee often have a normal sex ratio and spawning coloration that very closely resembles sea-run sockeye (Ricker, 1938). Within Okanagan Lake, there are two forms of kokanee that are distinguishable by their preference in spawning habitat: stream spawning and lakeshore-spawning kokanee live sympatrically from fry to adulthood (Dill, 1998a). 14 3.3 BIOLOGY The life span of kokanee is usually 3 to 4 years (Kokanee Salmon Heritage Project, 1997; McPhai l and Lindsey, 1970; Ricker, 1938). Kokanee are semelparous, producing all of their young in a single reproductive event over a relatively short period (Begon et al, 1990). Adults die within days of spawning. For Okanagan Lake kokanee, Sebastian and Scholten (1998) estimated that 70% of mature fish in their 1996 trawl sample were 4 year old fish (age 3 fish with fry considered to be age 0), while all mature fish in their 1997 sample were 3 year old fish (age 2 fish). The age of maturation for these fish is currently being clarified through otolith analyses of the 1997 sample of shore-spawners (Sebastian and Scholten, 1998). Water temperature strongly influences the timing of egg hatching and alevin development (Di l l , 1998c). Alevins are relatively independent for food as their yolk sac supplies them with nutrients (Burgner, 1991). During this stage, the fish are photonegative and positively geotactic. A s they mature, this preference for darkness and a benthic environment wans as the yolk sac diminishes (Burgner, 1991). For Okanagan Lake shore-spawning kokanee, D i l l (1998c) found that alevin emergence varied by as much as one month between the 1995 brood (early Apr i l 1996) and the 1996 brood (May 1997), depending on incubation water temperatures, for a total incubation time of 20 to 21 weeks from the end of October. Emergence from substrate marks the beginning of the fry stage. A s development continues, juvenile kokanee progress to a limnetic pelagic habitat where they remain for 2 to 3 years for further maturation. During both fry and juvenile stages, the most important food source of the fish is crustacean zooplankton (Foerster, 1968; Patalas and Salki, 1973; Thompson and Kuzyk, 1998b). While fry supplement their diet with midge, mayfly and caddis fly larvae, juveniles may supplement their diets with insects and other zooplankters in the euphotic zone (Burgner, 1991). A t sexual maturity, kokanee experience a physical transition similar to anadromous nerkids and cease to feed. Shore-spawning kokanee return to beach areas where spawning begins. 15 3.4 SPAWNING HABITAT The timing of spawning and selection of habitat by sockeye colonies are linked to the survival of all subsequent life stages of the following brood year (Burgner, 1991). In Okanagan Lake, shore-spawning kokanee deposit their eggs in mid to late October. The eggs are released in less than 2.5 m of water with more than 80% occurring in less than 1.5 m of water (Halsey and Lea, 1973). In recent years when spawning fish populations were lower, and especially when water conditions were calmer, most eggs were released in 0.25-0.5 m of water (Dill, 1998b). The majority of eggs were later found to rest 7-30 cm below the surface of substrate (Bull and Matthews, 1981; Dil l , 1998c). The composition of spawning substrate is also a primary consideration for characterizing spawning sites among members of Oncorhynchus nerka (Burgner, 1991; Burt and Wallis, 1997; Kerns and Donaldson, 1968; Olsen, 1968; Foerster, 1954; Krogius and Krokhin, 1948; Hatfield Consultants, Ltd., 1996). Northcote et al. (1972) reported stones on lake beaches appeared to be fractured, rough, jagged material loosely stacked without smaller gravel in between. SCUBA investigation determined that in several areas, stones were 5-13 cm in diameter; in other areas small boulders from 20-40 cm were typical (Northcote et al., 1972). Similarly, Halsey and Lea (1973) reported that 90% of shore-spawning occurred on angular rocks 7.5 to 30.5 cm in diameter; these were loosely stacked with no fines or small gravel in between. Bull (1977) observed that all spawners were associated with substrate composed of large flat rubble. Round rubble, straight gravel, milfoil encroached areas, and other substrate are not used for spawning (Bull, 1977). These reports are consistent with recent observations by Di l l (1996) that substrate at Bertram Creek Park are mostly angular rocks 10-20 cm in diameter, with flat, shale-like rocks found at the top of the substrate profile. Below the surface, particles were also platy and sub-angular but quickly decreased in size to an average diameter of 2.5 cm. The lowest substrate layer consisted of very fine silt at a depth that averaged 15 cm (Dill, 1998b). 16 Wind speed and direction contribute to lake currents and wave action. Aerial observations by Bull (1977) found that areas of extreme exposure to winter waves as well as areas of complete shelter were not used by spawners. More spawners used areas of intermediate exposure such as bays on exposed portions of the east shore of Okanagan Lake. Circulation favourable to kokanee involves a balance between its role in facilitating efficient gas exchange for incubating eggs and the potential for water currents to dislodge eggs among angular rubble material. Observations in other lakes indicated that groundwater springs are key characteristics in shoreline habitat selection. However, a comprehensive systematic search of groundwater sources along the entire lakeshore has not been reported in the literature and groundwater springs were not observed at current shore-spawning reaches of the lake (Neilsen, 1996). The significance of homing and site affinity to shore-spawners in Okanagan Lake is not well understood. It is assumed that kokanee monopolize the most optimal sites as spawners have been observed to move into sites immediately after others leave (Neilsen, 1996). 3.5 ECOLOGY Kokanee are ecologically important species in Okanagan Lake because they represent critical links in the foodchain. They compete with other fish to prey on zooplankton that feed on phytoplankton, and they are preyed upon during each life stage by fish and fowl. Of the life stages discussed above, those most dependent on food resources from the lake are the fry and juvenile stages. Egg and alevin stages rely on nutrients stored in the yolk sac, while spawning adults rely on energy reserves stored over the course of pelagic maturation. In recent years, both shore and stream spawning kokanee have been of such low abundance that it is improbable that they impose a significant level of competitive pressure on one another. Instead, it is likely that more abundant species have prominent roles. Within Okanagan Lake, fish competitors for crustacean zooplankton are peamouth chub and redside shiner in inshore areas during the summer months and juvenile lake whitefish during winter and spring (Wooding, 1994; Burgner, 1991; Foerster, 1968). Another competitor for zooplankton is Mysis relicta, an amphipod introduced to the lake 17 in 1966 (Shepherd, 1996; Lasenby, 1996; Nordin, 1996). The relative contributions of each species to competition with shore-spawning kokanee for food resources are not well understood; however, studies are currently underway to better define the biology and impact of introduced populations of mysids (Ashley and Shepherd, 1996). Predation on the various life stages of kokanee depends largely on the distribution and activities of both the predator and prey (Forester, 1968). During spawning, shallow water preference is an anti-predator behavior against larger predatory fish, however adults do fall prey to burbot, squawfish and carp (Smith, pers. comm., 1999) while eggs are eaten by prickly and slimy sculpins (Foerster, 1968; Burgner, 1991). D i l l (1998) reported intense predation by waterfowl in 1997 at Bertram Creek Park of Okanagan Lake: the common merganser, horned grebe, common loon and ring-billed gull were observed to feed on spawning kokanee. During fry emergence to inshore feeding areas, kokanee are highly vulnerable to predation by other fish species. Sculpins, and juvenile lake and mountain whitefish are common in shore areas of Okanagan Lake (Canada-BC Consultative Board, 1974c). Nocturnal emergence is likely an adaptation to this pressure. Juvenile kokanee maturing in the pelagic zone are susceptible to predation by rainbow trout, northern squawfish, and lake whitefish (Canada-BC Consultative Board, 1974c). 18 CHAPTER 4 - STUDY SPECIES- HOMO SAPIENS The following section will examine the historical development of the Okanagan Valley and relate current trends in population growth to land use patterns. 4.1 HISTORICAL DEVELOPMENT The settlement and development of south central British Columbia has been influenced by a wide range of activities including the fur trade, mining, extensive ranching, and intensive horticulture. David Stuart of the Pacific Fur Company was the first non-native to discover the Okanagan River by traveling up the Columbia River in 1812 (Woodward and Woodward, 1993). By the early 1820s, the Okanagan became a major trading route into forts further into the interior (Canada-BC Consultative Board, 1974a; Kerr et al., 1985). In 1857, gold was discovered in the Fraser River (Canada-BC Consultative Board, 1974a; Kerr et al., 1985). Within a few months 20,000-30,000 people swarmed to the area (Woodward and Woodward, 1993) passing through the Okanagan to gold fields near Yale, Boston Bar, Lillooet, and later to the Caribou and the Similkameen Valley (Canada-BC Consultative Board, 1974a). The Canada-BC Consultative Board (1974a) estimated that between 1862 and 1864, 14,000 cows, horses and sheep were imported to the Okanagan to support the growing population of homesteaders. From the late 1890s-early 1900s, promotion by land development companies, the Canadian Pacific Railway and the provincial government effectively expanded settlement and transformed the economy from ranching to fruit growing (Kerr et al , 1985). By 1911, the Okanagan was B C s leader in orchard production and in 1914, the federal government established an agricultural research station in Summerland to guide efforts in fruit industry research (Kerr et al., 1985). Grape production was introduced on a small scale in Kelowna in 1926 (Kerr et al., 1985), however it did not gain popularity until the 1960s and 1970s when vineyards were encouraged by the provincial government (Kerr et al, 1985). Between 1961 and 1971, the Okanagan experienced another significant change stimulated by large sums of federal and provincial funds aimed at diversifying the economy. The financial programs were 19 largely successful at transforming the economic structure "from being one dominated primarily by resource-based activities (agriculture, forestry and mining) to one dependent on secondary and tertiary economic activities associated with non-resource based manufacturing, tourist and service industries" (Kerr e t a l , 1985). 4.2 CURRENT TRENDS Current census data (Statistics Canada, 1997) indicates that population growth stimulated by the federal and provincial incentives program continues today (Figure 8). This growth slowed slightly in the early eighties and was rejuvenated by 1986 with the construction of the Coquihalla Highway for fast access to the southern interior from the Lower Mainland. Between 1991 and 1996, the degree of residential population growth in the Okanagan Valley (18.9%) was greater than the provincial rate (13.5%; Statistics Canada, 1998). The North Okanagan and Okanagan-Similkameen Regional Districts ( N O R D and O S R D , respectively) experienced similar rates of growth while the Central Okanagan Regional District ( C O R D ) expanded most rapidly (Figure 8). 800000 1 CORD OKVALLEY OSRD NORD Kokanee T - c o m h - a j T - o o m h - O T T - r o m i-^i^-h-r-r-cooooooooocococT) < J > G > O I O > 0 0 > 0 > < J ) 0 ) 0 ) 0 > 0 > 0 ) Year Figure 8- Population Change from 1971 to 1996 (CORD= Central Okanagan Regional District, NORD= North Okanagan Regional District, OSRD= Okanagan-Similkameen Regional District, O K V A L L E Y = Okanagan Valley) (Data source: Statistics Canada, 1997; B . C . Ministry of Environment, Lands and Parks, 1996). 20 The majority of the population was within the working age bracket of 25-54 years; the average age of the population was 40. Of those employed, 74% worked in a service based tertiary industry, 20% in manufacturing and construction, and 6% in a resource based primary industry such as agriculture (Statistics Canada, 1998). These figures are similar to the current provincial averages (Figure 9) and indicate a 13% decrease in employment in the agricultural, mining and logging sectors, a 7% increase in manufacturing and construction, and a 6% increase in tourism and retail from 1961. a. Industry Distribution of Work Force in the Okanagan • Primary (Agriculture and other resource-based) • Secondary (Manufacturing and construction) • Tertiary (Tourism and retail) Figure 9- Industry Distribution of Work Force in the Okanagan and BC-These figures reflect only the number of employed people, not the relative monetary value of each type of industry. (Data source: Statistics Canada, 1998) 21 Two large studies have examined major uses of the land surrounding Okanagan Lake. The Canada-B C Consultative Board (1974) conducted a survey from 1969-1973 to develop a watershed management plan and Environment Canada's Lands Directorate (1985) conducted a survey from 1981-1985 to determine the impacts of federal programs in the region. The boundaries of each study do not overlap with one another nor the boundaries of the current study. Consequently, the qualitative information they provide are more useful than the quantitative data. In 1970, more than 2/3 of the Okanagan Basin supported forest cover. Both irrigated and dryland farming occupied smaller parcels (8%) of land at lower elevations. Because of higher levels of precipitation, dryland cultivation was mainly situated in the north end of the Basin. Residential, commercial and industrial subdivisions occupied still smaller areas (3%) of land in the valley bottom; most of this land was formerly prime agricultural land (Canada-BC Consultative Board, 1974a). Between 1958 and 1981, the total land area allocated for all agriculture related activities (forage, annually tilled crops, grazing, orchards, vineyards, nurseries) in the study area for the federal land use study decreased from 81% in 1958 to 61% in 1981 (Kerr et al., 1985). However the area allocated for fruitlands (orchards and vineyards) remained between 18.5% (1958) and 18.0% (1981; Kerr et al., 1985). During this period, 3,818 hectares of land were converted to orchards and 1,964 hectares were converted to vineyards; over half of this area (50.1%) was derived from forage and grazing areas. Urban development grew by 6,530 hectares within this period; 22.9% of this land was converted from fruitlands, while 38.0% was converted from grazing or forage lands. The rate of loss in agricultural lands through direct transition to residential lands and urban related uses is reduced to some degree by zoning regulations, however agricultural lands may be diminished indirectly through fragmentation for rural land development or rural hobby-farm development. Rising land prices also increase pressures for converting productive agricultural lands to more profitable urban developed areas. Chapter 7 discusses land use current land use changes in detail. 22 CHAPTER 5 - A CASE FOR INTERACTIONS In support of this study's goal to examine relationships among human shoreline activities, kokanee abundance and shoreline spawning habitat, the following literature review seeks mechanisms for interactions between fish abundance and the availability of fish habitat, between land use and riparian shoreline characteristics, and between fish abundance and upland human activities. 5.1 FISH ABUNDANCE AND FISH HABITAT Many stocks of Oncorhynchus salmonids in western North America currently risk extinction or have declined from 50-85% of their average historical abundance (National Academy of Sciences, 1996). While theories abound to explain these observations, habitat alteration or loss has been associated with nearly all of these stocks (Giannico, 1996; National Academy of Sciences, 1996; Nehlsen et al., 1991; Northcote and Burwash, 1991; Armour et al, 1991; Larkin et al, 1959). 5.1.1 The Concept of Habitat Change "Fish habitats" are parts of the environment "on which fish depend, directly or indirectly, in order to carry out their life processes" (Department of Fisheries and Oceans, 1987). More specifically, they relate to the suite of resource conditions that fish require at various stages of their life history and are defined by factors listed in Table 2. Physical factors such as water level fluctuations and substrate characteristics interact with chemical and biological characteristics of a particular environment to create a unique set of variables that fish adapt to and rely on for survival, growth and reproduction (Moyle and Cech, 1996; Ross, 1997; National Academy of Sciences, 1996). 23 Table 2- Factors that Affect the Abundance of Fish in Temperate Lakes and Reservoirs (Moyle and Cech, 1996; Ross, 1997; National Academy of Sciences, 1996) PHYSICAL Temperature Light Water movements Water level fluctuations Size Substrate CHEMICAL Gases Water hardness pH Nutrient concentrations BIOLOGICAL Disease and Parasites Predation Competition SIGNIFICANCE Affects density of water, solubility of dissolved gases, distribution of ions within water column, fish physiology Affects water temperature, photosynthesis, depth to which phytoplankton, periphyton and macrophytes can grow, visibility of prey to fish and fish to predators Affects distribution of zooplankton and thus zooplankton-feeding fish, visibility of fish in shallow waters to predatory birds Extreme drops in water level can expose nests of eggs and alevins, rapid rises may cover nests with water depths intolerable to spawning fish and prevent establishment of emergent plants, periodic flooding of shoreline areas allows introduction of allochthonous carbon Affects the relative significance of watershed inputs to lake water quality and influences the retention of contaminants in lake Provides refuge areas and protective cover for eggs and young fish, provides surface for aquatic plants and benthic invertebrates that can serve as both food and cover for fish SIGNIFICANCE Dissolved oxygen necessary and carbon dioxide is waste metabolite for aerobic organisms, carbon dioxide is necessary and oxygen is metabolite of primary production for photosynthetic autotrophs Affects availability of other chemicals to fish Affects availability of other chemicals to fish Phosphorus and nitrogen are essential elements for photosynthesizing organisms SIGNIFICANCE Reduces health of individual fish and their ability to resist stresses of sub-optimal physical and chemical lake conditions, avoid predation, compete for resources and reproduce Affects structure of fish populations and communities, competitive pressures within and among populations and communities Affect availability of food and habitat resources for individual organisms, populations and communities "Lost habitat" is habitat that is no longer accessible to fish. If the resources necessary for kokanee to carry out their life processes are unavailable, it is expected that fish abundance will reflect this deficiency. "Altered habitat" is habitat that has changed in some integral way but is still accessible to fish. Because habitat alterations involve an intricacy of physical, chemical and biological interactions, they can have positive or negative outcomes that are difficult to predict (National Academy of Sciences, 1996). For instance, thinning of riparian vegetation may increase solar radiation and water temperatures, thereby 24 promoting photosynthetic processes in energy limited systems and eventually increasing zooplankton production. Likewise, warmer temperatures increase the developmental rate of eggs and alevins. With early exhaustion of the yolk sac, fry can be prematurely advanced to emergence and face increased risks of predation (Groot and Margolis, 1991). Similarly, increased temperatures can decrease oxygen solubility while increasing the metabolic requirements of fish (Brown, 1985), thereby taxing rather than favoring them. The availability of resources and concurrent demands that comprise the habitat of a fish influence its progression to the next life history stage and ultimately its fitness or the number of progeny a fish is able to produce. 5.1.2 Mechanisms for Correlations The mechanisms for the positive and negative effects of habitat alterations on fish abundance can be direct or indirect. Both types of mechanisms can have acutely harmful or subacute long term effects which include a reduced ability to compete for food and avoid predation (France, 1997) or reduced fecundity and fitness of offspring. Habitat conditions that can have direct negative effects on spawning and incubating stages of fish include ultra-oligotrophic conditions, cover homogeneity, extreme temperatures, low dissolved oxygen conditions, high suspended sediment levels, toxic pollutants and inappropriate water movements. Low food availability can increase both interspecific and intraspecific competition for food reserves (Begon et al, 1990), while cover homogeneity can both limit algal and plankton biomass (Scarnecchia and Bergersen, 1987) as well as increase the risk of predation. As previously mentioned, elevated water temperatures can delay spawning, accelerate hatching (Burgner, 1991), and generally increase the metabolic demands of fish. They are also associated with lower dissolved oxygen levels in stagnant waters. Both low dissolved oxygen and high suspended sediment levels contribute to difficulties in gas exchange. Pollutants may be acutely lethal or sublethal with prolonged chronic exposure, reducing the fitness of fish or their offspring. Similarly, inappropriate water movement can have direct negative effects on fish. Under calm water conditions, kokanee tend to spawn at shallower depths along the beach (Dill, 1998). The more shallow the water in which eggs are released, the more vulnerable the eggs and alevins are to risks of dessication and 25 freezing during reservoir drawdown events. In contrast, turbulent water can also dislodge eggs released among the crevices of large angular rocks to areas with even less hospitable conditions. Indirect mechanisms for correlations between habitat changes and spawner, egg, alevin and fry abundance follow ecological energy flows. Water clarity and the amount of habitat cover have been shown to influence water temperature, the amount of light energy available to autotrophs consumed by zooplankton, and the availability of allochtonous carbon sources. Competition for limited resources may increase the foraging range of fry, thereby increasing their risk to predation while exposing them to an entirely different environmental profde. The level of terrestrial and aquatic based predation on spawner success may affect the exact location of egg deposition, which in turn, determines the freshwater environment to which the developing fish are initially exposed. Food chain interactions serve as pathways for the biomagnification of contaminants such as pesticide residues in riparian insects and benthic invertebrates. A l l of these direct and indirect factors have the potential to result in correlations between the availability of habitat and fish abundance. 5.2 LAND USE AND HABITAT CHARACTERISTICS "Many human activities—such as forestry; agriculture; grazing; industrial uses, commercial, residential and recreational development; and flood control—have a variety of adverse effects on salmon habitats" (National Academy of Science, 1996). For example, they can increase water temperature, affect dissolved oxygen and contaminant levels in water, increase soil erosion and sedimentation, reduce cover homogeneity, and generally affect the movement and amount of water available, thereby negatively altering fish habitat. 5.2.1 Mechanisms for Correlations Two mechanisms of habitat change are natural disturbances and anthropogenic perturbations (Giannico, 1996; National Academy of Science, 1996). Human inflicted changes can occur directly to a particular habitat or through intervention or prevention of natural developments (National Academy of Science, 1996). Either way, fish production can be affected especially when the change occurs on a spatial 26 or temporal scale that differs fundamentally from natural disturbances (National Academy of Science, 1996), alters the frequency or magnitude of natural disturbances, or diminishes the ability of the fish to naturally recover from the disturbance. In the Okanagan Valley, human activities that have occurred inland from kokanee spawning habitat over the years (Chapter 4) include forestry, agriculture and urban development. Logging activity occurred in the past for land settlement and developments along the lakeshore, and still occurs at higher elevations. Currently, there are few formal timber harvesting activities close to the shoreline. However, removal of tree cover occurs on private properties by landowners and even protected provincial and municipal parks by Parks staff when public safety is deemed to be at risk by large mature trees (Smith, pers. comm., 1999). The effects of forestry activities are well studied (Giannico, 1996; Evans et al, 1996; Brown, 1985). Forest ecosystems are unique in the hydrologic regime by which they are characterized. Stands of trees are significant in the amount of atmospheric precipitation and overland flow they intercept, the subsurface or groundwater flows they draw upon, and the water they transfer through evapotranspiration. They also filter runoff and provide shading to reduce the amount of water evaporated from lakes. Removal of these stands of trees, compaction of the soil and the concurrent construction of roads for access eliminates these interactions, increasing the runoff of water and materials transported in the water to riparian shoreline areas and potential fish habitat. This renders littoral areas more vulnerable to upland contaminants (Larkin et al, 1959; Meehan and Platts, 1978; Platts, 1981; Brown, 1985; Department of Fisheries and Oceans, 1987; Evan et al, 1996). The loss of trees is also associated with increased soil erosion and decreased large woody debris (Larkin et al, 1959; Brown, 1985; Department of Fisheries and Oceans, 1987; Evans et al, 1996). Increased inputs of soil into shoreline areas decreases water transparency, increases temperature and decreases oxygen transfer beneath substrate layers. Decreased woody debris results in reduced allochthonous carbon and reduced resting, hiding and foraging areas for rearing fish. Invertebrates and insects dependent on the forest ecosystems are also no longer available to emerged fry. 27 Changes imposed by the clearing of forests also occur in agricultural areas (Christensen et al, 1996; Wang et al, 1997; Wissmar et al, 1994; Geier et al, 1994; Armour et al, 1991; Meehan and Platts, 1978; Platts, 1981; Irwin and Noble, 1996; Evans et al, 1996). However, they are exacerbated by the removal of native vegetative ground cover, land tillage, soil erosion and soil compaction by grazing livestock (Larkin et al, 1959; Giannico, 1996). Elements washed into the lake with runoff are also more varied. While the erosion of rich topsoils, suspended sediment and silting are problems common in both forestry and agriculture, agrochemicals such as pesticides and fertilizers, excess nutrients, fecal coliforms (Larkin et al, 1959), and pharmaceuticals fed to livestock are additional concerns in agriculture. Although burgeoning, the number of studies performed on the effects of urbanization on lake systems is still relatively small (Giannico, 1996). A s with agriculture, the hydrological changes to surface runoff and subsurface flow are altered more so than for forestry. However, urban development expands the area of impermeable land surfaces such as roads, parking lots, sidewalks and rooftops which substantially increases surface runoff and decreases subsurface flow to the lake (Wang et al, 1997; Evans et al, 1996). Through long dry periods characteristic of the Valley, debris and toxic materials accumulate on these impervious surfaces. During rainfall events, stormwater runoff represents a non-point source of pollution which includes "high levels of suspended solids (ie. rubber particles, asbestos fibres, general litter), nitrogen, phosphates, hydrocarbons, phenols, chlorides, lead and other metals, and coliform bacteria" (Giannico, 1996; Evans et al, 1996; Firecock and Doherty, 1995). Urban areas also differ from agriculture areas in the number of humans that inhabit the area and have access to shoreline areas: human activities such as boating, beachcombing and swimming seem relatively innocuous, however all add to the anthropogenic stresses imposed on shoreline habitats. Wetlands are "coastal or inland transition areas between terrestrial and aquatic habitats where the water table is normally at or near the soil's surface or where the land is covered by shallow water...[and] include all seasonally or permanently flooded areas..." (Ross, 1997). Wetlands have historically been drained for agricultural use, conversion to urban centres or paving for transportation networks as their function in ecosystem health has traditionally been neglected. They have also been negatively impacted by 28 flood control projects that inhibit the recharge of wetland areas. The deterioration or elimination of wetlands results in the loss of nursery, feeding and spawning areas for many shoreline fish and wildlife, the loss of natural filters for eroded material and chemical contaminants from associated water ways and overland runoff, and natural flood and drought protection that wetlands offer. From the literature, it appears that surface and subsurface flows facilitate many interactions between terrestrial and aquatic environments. These occur naturally but are effectively changed by human interventions that range in area and permanence; forestry, agriculture and urban development are dominant land based activities that have decreased the permeability of land surfaces in the Okanagan Valley. Urban development has the most significant and permanent impact for a given area on the hydrology of a system, followed by agriculture and forestry. A n additional factor causing habitat change is the elimination of wetland areas for agricultural and urban development. 5.3 FISH ABUNDANCE AND LAND USE ACTIVITIES While the literature contains many reports of linkages between the availability of suitable habitat and fish abundance and the influence of land use on fish habitat, there are currently few studies that have directly correlated land use with fish productivity (Larkin et al, 1959; Meehan and Platts, 1978; Armour et al, 1991). Nevertheless, the concept is intuitive and commonly alluded to (Larkin et al, 1959; Meehan and Platts, 1978; Armour et al, 1991; National Academy of Sciences, 1996; Christensen, 1996; Wang et al, 1997; Mcintosh et al, 1994). 5.3.1 Mechanisms for Correlations The mechanism for correlations between land use and fish abundance is likely facilitated mainly by habitat changes. From the literature, it is expected that fish abundance should be positively correlated with the availability of suitable habitat (through mechanisms discussed in Section 5.1.2), and land use intensity and associated surface impermeability should be negatively associated with the availability of habitat (through mechanisms discussed in Section 5.2.1). Thus, fish abundance is expected to be negatively correlated with the land use intensity and surface impermeability. 29 CHAPTER 6 -FISH ABUNDANCE STUDY To characterize spatial and temporal changes in spawning activity, fish enumeration data collected by fisheries staff of the B C Ministry of Environment, Lands and Parks were analyzed. 6.1 METHODS AND MATERIALS 6.1.1 Source of data Fish enumeration data were collected from 1972 to 1997 by fisheries staff of the B C Ministry of Environment, Lands and Parks. Thompson (1998) and Shepherd (1998) describe the inventory methods in detail. In 1997, fixed-wing aircraft surveys were performed a few days before the first day fish were expected to spawn based on observations from previous years. When spawning activity was identified, actual counts were conducted using shoreline boat cruises. Enumeration was conducted with a minimum crew of three fisheries staff. A n experienced fish counter situated on top o f a slow moving boat visually estimated the number of fish per reach. The same boat and fish spotter were used to perform all counts for each day of sampling. A second crew person helped to navigate the cruise using aerial photos of the shore-spawning reaches, organized and recorded all fish data per reach, and reported additional information such as the time of sampling, weather conditions, visibility and water temperature. These are characteristics that may affect the accuracy of fish counts. The third crew person was an experienced boat operator familiar with the annual fish enumeration route and knowledgeable enough about the bathymetry of the lake to safely orient the boat and maximize visibility in shore-spawning areas. For the current study, M E L P provided enumeration data for the period from 1973 to 1996. Field sampling notes complemented the data set for discrete periods from 1972 to 1997. For the purpose of referencing fish abundance data, Okanagan Lake was divided into 4 quadrants; the floating Kelowna bridge separated the lake into north and south halves. The southeast, northeast and northwest quadrants were further divided into 78 fish counting reaches (Figure 10). N o sampling was performed in the southwest quadrant since kokanee were rarely reported to spawn in this quadrant. To locate annual fish sampling 30 N W Quadrant Reaches 50-77 SW Quadrant | Reach 78 Peachland f r-r""-7' N E Quadrant Reaches 22b-49b SE Quadrant Reaches l-22a \ v c i A Jy £ Naramata Summerland \ V Penticton Figure 10- Map of Okanagan Lake and Study Sites 6.1.2 Analyses Performed The first level of analysis served to review the information provided in the database. The database was inventoried for the completeness of count data for each reach and year. Data for years when counts were generalized for quadrants and not specified for reaches were excluded from analyses. Correlation analyses were also performed to determine the cyclicity o f fish abundance through time. The second level of analysis considered spatial and temporal trends in spawner abundance. Exploratory steps for significance testing of these trends considered the frequency distribution and normality o f the dataset. Within vs. among reach analysis tested the null hypothesis that all reaches have the same annual peak abundance at a significance of a= 0.05. Similarly, temporal trends were tested with the null hypothesis that the same annual peak abundance occurred over the study period. Results o f spatial and temporal trend analyses were then integrated for a classification and reduction o f the number of reaches for further study. For the classification, it was important that a substantial amount of data be used to characterize each reach. Consequently, a minimum criterion of 16 data points per reach (16/18 or >85% available data) was set. Mann-Whitney U-tests were applied to 31 Results of spatial and temporal trend analyses were then integrated for a classification and reduction of the number of reaches for further study. For the classification, it was important that a substantial amount of data be used to characterize each reach. Consequently, a minimum criterion of 16 data points per reach (16/18 or >85% available data) was set. Mann-Whitney U-tests were applied to identify reaches with sufficient data where current and historical abundance were significantly different. These reaches were paired with reaches where differences were not statistically significant. Additional reaches were also identified to represent reaches where observations of spawning activity were rarely reported. 6.2 RESULTS 6.2.1 Review of Fish Enumeration Data When data from the enumeration database and field notes were pooled, shore-spawning data for each quadrant were available for the period from 1972-1997. O f 1,774 data points reported, representation by reaches in the southeast quadrant overwhelmed that of the other quadrants; 45.32% of all records described fish abundance in the southeast quadrant, compared to 29.93% and 24.58% from the northeast and northwest quadrants, respectively. Reports for the southwest quadrant were infrequent; 3 records representing 0.17% of all data points over all years were documented for this quadrant. Reach delineated data were available for 1973-74, 1978-79, 1983, and 1985-1997. Data for 1972, 1975-77, 1980-82, and 1984 were not delineated for each reach and therefore excluded from further analyses. O f the 18 years when reach specific data were available, the number of observations ranged from 2 at reach 78 to 43 at reaches 8-10. This indicates that reaches were not sampled with consistent effort over all sampling periods. In recent years, many reaches were surveyed more than once. Fish enumeration trips were planned to extend over the length of the entire spawning period, and intended to capture the peak spawning days. Sampling usually began after mid-October (Table 3). The earliest start date occurred in 1985 when counting began on October 12 (Table 3). More commonly, counts began on October 19 (1973, 87, 88, and 89) or October 20 (1978, 92, 93, and 97; Table 3). The latest reported start date occurred in 1986 when sampling began on October 29. Sampling usually ended in the 32 last week of October. The earliest end date was October 22 in 1973 and the latest was November 12 in 1996. More commonly, sampling ended on October 26 (1978, 88, 92, 94, and 95). The length of each sampling period also varied with the shortest being 3 days (1986), the longest being 22 days (1995) and the most common being 9 days (1987, 89, 94, and 97). Within the sampling period, actual field days ranged from 2-8 days (2 days in 1973, 8 days in 1983, 95, and 96; Table 3) and most commonly took 5 days (1974, 89, 90, 92, and 94). O f these field days, the number of visits per reach was greater in recent years. From 1973-1988, reaches were visited once and the number recorded in the database was conservatively assumed to represent peak counts. In subsequent years, the number of visits per reach increased to 6 in some quadrants. According to Smith (pers. comm., 1999) of the M E L P Fisheries Branch, the length of the sampling period increased with declining fish numbers to ensure that the true peak count was actually observed. In some years, weather conditions prevented more frequent surveys. In 1976, windy conditions prevented sampling completely (Smith, pers. comm., 1999). Table 3-General Sampling Route and Level of Sampling-Parameters Earliest Latest Most Common Start Date October 12 October 29 October 19/20 End Date October 22 November 12 October 26 Parameters Minimum Maximum Most Common Length of Sampling Period 3 22 9 Actual Field Days 2 8 5 To determine whether variations in fish abundance were real or due to natural cycles in spawning activity, the number of fish counted each year was correlated with fish counts in each succeeding year at increasing time intervals. In a cyclic series, high correlations occur when the intervals in years match corresponding phases of the cycle. For a population that does not cycle, the correlogram dampens down quickly to low and insignificant levels of correlation. Figure 11 shows very little dampening characteristic of quasi or noncyclic series (Begon et al, 1990). This indicates that the population of kokanee truly does experience cycles in abundance and that these series may be approximately 7 years in length. Figure 11 also reveals much noise between years and slight dampening in later years. Longer cycles in the first 2/3 of 33 the graph may suggest the abundance of 3 year old spawners mixed with 4 year old spawners. Shorter cycles in the latter 1/3 of the graph may suggest the relative abundance of other age groups as well as the effects of disturbances external to but impacting the kokanee population. 1.0 .8 o .5 sz * .3 "c CD 0.0 E co -.3 CD Q. CO -.5 -.8 -1.0 "-cMcifincoscocDOT-iNico'^ mcoscocnO'-wn'* i-T-T-T-T-T-T-i-T-T-MCNCNCNCN Time Interval (Years) Figure 11- Correlogram of Fish Abundance 6.2.2 Analyses of Spatial and Temporal Trends From the review of enumeration data, it was found that some reaches were visited more frequently than others within each year. In the present study, when only one data point was reported for a reach, this record represented the annual peak count for the reach. If more than one count was reported for a reach, the maximum value was used to represent the annual peak count for trend analyses. Chi-square analysis of the data suggested a nonnormal frequency distribution of the data (p< 0.00). Consequently all significance testing offish abundance employed nonparametric methods. SPATIAL TRENDS Current fish abundance was significantly greater in the southeast and northeast quadrants of the lake (p97-95= 0.001, p90s< 0.000). Throughout the 1990s, fish abundance was greatest in the southeast quadrant, however in the most recent 3 years, fish abundance was greatest in the northeast quadrant (Figure 12a). Current fish abundance was not significantly greater at any one particular reach within the lake (Figure 12b). 34 100Q 3000' to o a> cn 0 2000> a) o c ro "O c 3 1000' .a < SE NE NW -in0)C0r^ -i-^C»CNC0OC'0r--O'*f00CMCOO-*l-C0 T-i-CNCNCNCOCO'<J-'<if<a-miomcDCDr~r~r--Figure 12- Current Fish Abundance among Quadrants (a) and Reaches (b) of the Lake Historical fish abundance was significantly different among the southeast, northeast and northwest quadrants of the lake (p73-75= 0.010, p= 7 o s = 0.012). The data further indicate that the southeast quadrant supported the most spawning activity, followed by the northeast quadrant and the northwest. Spawning activity was rarely observed in the southwest quadrant (Figure 13a). Historical fish abundance was not significantly greater at any one particular reach within the lake (Figure 13b). 10000 1400G 173-75 [ I f i1970s T - in 0) CO i- OO CM CO O CO r- o OO CM CD O 00 T - T - CM CM CM co co LO Ln co co r~ r~ r-SE NE NW SW a b Figure 13- Historical Fish Abundance among Quadrants (a) and Reaches (b) of the Lake Reaches that currently support higher spawning activity did not support higher abundance historically. There is only a weak correlation between reaches in their abundance during the early 1970s 35 and their abundance during the last three years (rho= 0.477, p< 0.000). Similarly, there is only a weak correlation between reaches in their abundance through the 1970s and their abundance through the 1990s (rho= 0.448, p< 0.000). A s expected, spawner abundance in the early 1970s is positively correlated with abundance at the same reaches throughout the decade (rho= 0.979, p< 0.000), and fish abundance in the late 1990s is positively correlated with abundance at the same reaches throughout the 1990s (rho= 0.855, p< 0.000). TEMPORAL TRENDS Fish abundance declined significantly from one decade to the next (p< 0.000). Spawning activity within the lake was highest in the 1970s and lowest in the 1990s (Figure 14a). Spawning activity also differed significantly among years over the study period (p< 0.000). Figure 14b illustrates peak enumeration data pooled from all reaches vs. years. Abundance for 1972, 75-77, 80-82, and 84 were excluded from the graph because their counts were not site delineated for later comparisons. They do not represent years of no spawning activity. The highest reported abundance of 50,550 occurred in 1974 at site 14. The lowest reported peak abundance was zero at a number of sites in recent years. When all site data were pooled, the highest average occurred in 1974 (9,103); the lowest average occurred in 1993 (88.31). 6000C 50000 • • 4000C I 30000 • I 20000 | i • • • 10005, 1 m , u j . o i l i l i i . l l l i i i . i i i i ro in co t~- oo co o T- OJ co m co N- OO O> O T- CN ro in co r-r^r^r r^^ t^ r r^^ cocooooococooorocx>coo^o^o^c7)C7)cxcxo> C^CT)CT)CT)O}C^O5C^O)C^O)O}O^O)C7>O>C0CXO)O)O)O)O)O)G> Figure 14- Temporal Comparison of Fish Abundance through the Decades (a) and among Years (b) 36 SPATIAL- TEMPORAL TRENDS The magnitude of decline among quadrants was significantly different (pi s t vs.Las6yre= 0.041). The greatest change was observed in the southeast quadrant while the lowest declines were observed in the northwest quadrant (Figure 15a). The magnitude of decline among reaches was not significantly different (Figure 15b). a Figure 15- Comparison of Declines in Fish Abundance among Quadrants (a) and Reaches (b) Reaches that historically supported the greatest spawning activity were significantly correlated with reaches that recently demonstrated the largest declines. There is a strong negative association between fish abundance in the early 1970s vs. change in spawning activity throughout the decades and especially in the late 1990s (Table 4; Figure 16). There is also a strong negative association between fish abundance throughout the 1970s vs. change in spawning activity throughout the decades and the late 1970s (Table 4; Figure 16). Table 4- Spearman Rank Correlation Results for Historical Spawning Activity vs. Declines in Fish Abundance Historical Fish Abundance Aist-Last 3vrs A70S-90S #Fish1973-75 Rho -.989 -.919 P .000 .000 N 76 81 #Fish 7 0 s Rho -.963 -.972 P .000 .000 P .000 .000 N 76 81 37 o < _c co Q. CO CL) c co O " 1970s-90s vs. Mean of 1970s ° 1 st-last 3yrs vs. Mean of 1973-75 0 10000 20000 30000 Historical Fish Abundance Figure 16- Strong Negative Correlation between Current Declines in Spawning Activity and Historical Fish Abundance 6.2.3 Classification and Selection of Reaches for Land Use and Habitat Studies The classification of reaches by temporal trends considered significant changes for reaches with at least 16 observations. A l l reaches experienced a decrease in fish numbers since the early 1970s. Significant (a< 0.10) changes occurred at 26 reaches. Among these reaches, 11 were selected for further land use and habitat studies (Table 5). A n additional 11 reaches were chosen to represent reaches where significant changes have not occurred (Table 5), for a total of 22 enumeration reaches for more detailed study (Figure 17). Five additional reaches were selected to represent areas seldom inventoried for fish due to their rarity in past years (Figure 17). Table 5- Enumeration Reaches Selected for Further Land Use and Habitat Studies Significant Decline Not Significant Reach P(A) Reach P(A) 8 0.008 3 0.209 11 0.016 4 0.493 14 0.023 6 0.705 21 0.086 7 0.449 31 0.020 9 0.850 32 0.008 16 0.750 33 0.0.08 19 1.00 37 0.081 20 0.131 60 0.014 29 0.130 61 0.007 75 0.127 63 0.007 78 0.167 38 .33 » < .37»< -29 -20 •19 •16 "11 *-< -21 *-< »•< = Enumeration Sites where Significant Changes in FishiCs have Occurred + = Control Sites • Wfcnetrc Figure 17- Sites Selected for Detailed Land Use and Fish Habitat Studies 6.3 DISCUSSION Fish enumeration data collected by regional fisheries officers of the Minis try ,of Environment provided the most comprehensive source of data for the present study. Inventories were intended to coincide with the peak of kokanee spawning during the last two weeks of October and varied in length as well as the number o f times reaches were revisited. Fish abundance was positively correlated with the length of the sampling period and the number o f field days per reach. Additional data on variables that could affect the accuracy o f fish counts were reported in recent years and could prove beneficial to the interpretation of fish counts i f collected consistently. Thompson (1998) evaluated the methodology for fish enumeration, discussed the possible sources o f error and made recommendations for the improvement of future counts. Autocorrelation of fish abundance data from successive years at increasing intervals suggested the cyclicity o f the population as well as recent stresses to the kokanee. Cycles appeared to be 7 years in length, however this is likely due to the presence of both 3 and 4 year old spawners previously observed by Sebastian and Sholten (1998). Burgner (1991) reports that many nerkids undergo a semelparous 3 year 39 history. Shepherd (1996) makes the assumption of a 3 year recruitment period for shore-spawning kokanee. A s such, analyses of trends in fish abundance assumed a 3 year cycle. The southeast quadrant demonstrated the greatest variation in fish abundance: both the highest and lowest counts were reported for reaches in this quadrant. Furthermore, the spawning activity in the southeast quadrant appears to have decreased more so than the northeast and northwest quadrants. Significance tests suggested that abundance characterizing each quadrant were statistically distinct and that counts in the southeast and northeast quadrants are similar to one another as were abundance in the northeast and northwest quadrants. The highest fish counts were reported in 1974 while the lowest were reported in 1993. From 1985 to 1997, reaches generally showed lower counts than from 1973 to 1984. These findings are consistent with reports that kokanee stocks are fast declining and strengthen the concerns that led to the 1995 kokanee closure in Okanagan Lake. Temporal changes in fish abundance was demonstrated to be strongly negatively correlated with historical fish abundance. Reaches that supported high spawning activity in the past currently experience the greatest declines in fish abundance. While decreases in fish abundance occurred at all enumeration reaches, only 26 of these sites experienced statistically significant declines between the 1970s and 1990s. From these sites, 11 were selected for further land use and habitat studies. Furthermore, 11 sites where significant changes have not been proven and 5 sites where enumeration data were unavailable were selected for comparison of land use and habitat characteristics. 40 CHAPTER 7 - LAND USE STUDY To characterize spatial and temporal changes in land use and cover, shoreline reaches and corresponding areas 500 m from the shoreline were examined from 1963 to 1996. 7.1 METHODS AND MATERIALS 7.1.1 Source of data Aerial photos taken from 1963 to 1996 were the primary source of historical land use and cover data. A geographic information system (GIS) was developed to consolidate geographic data and analyze the results of aerial photo classification. A digital base map was first developed using Terrasoft GIS software and Canadian Hydrographic Service map 3052 (Okanagan Lake at 1:50,000 scale). The following themes were georeferenced to the digital map: lake border; lake depths at 2 m, 5 m, 10 m, 20 m, and intervals of 20 m to a maximum depth of 220 m; major tributaries; major roads; the Kelowna bridge and urban centres. Six National Topographic System map sheets (82L/6, 82L/4, 83E/12, 82E/13, 82E/14, and 82L/3; 1: 50,000 scale) were also digitized to a distance of 1,500 m from the perimeter of the lake for topography and linkage to the Ministry of Environment's fish enumeration reaches. Fish abundance data and fish habitat data were further referenced to each enumeration reach on the base map. Aerial photos were selected for the greatest resolution available within the study period. Photos collected for the study represented the following years: 1963 (1:20,000 scale), 1971 (1:6,000 scale), 1981 (1:6,000 scale), and 1994-96 (1:15,000 scale). Interpretation involved four general stages: coarse comparison of all photos for derivation of a land use and land cover classification system, testing and ground-truthing of the classification system on the 1994-96 set of aerial photos, refinement of the classification system, and digitizing of land use polygons into the map base. 7.1.2 Analyses Performed Indicators used to measure human disturbance along the shoreline and in nearshore areas were the density of docks and buildings per kilometer at each of the study reaches identified in Chapter 6 (Figure 41 17). Land use was delineated for areas up to 500 m from the shoreline. A 500 m buffer was chosen as an arbitrary starting point to consider land use and cover characteristics adjacent to the lakeshore. Variations in topography, geology and hydrology could be better incorporated into comparisons than the typical 30 m buffer used as part of the Forest Practices Code. A multilevel classification system (Table 6) was adopted. Level I classes were delineated for the entire lake using 1963 and 1994-1996 aerial photos, and for specific reaches using 1971 and 1981 air photos. Levels II and III classes were delineated for study reaches using air photos for all years. These categories listed in Table 6 were selected because they could be identified most consistently given the resolutions of the air photos. Table 6-Land Use and Land Cover Classification for Air Photo Interpretation Level I Level II Level III Development (100) Residential (101) Commercial (102) Industrial (103) Institutional & Recreational (104) High density (111) Medium density (112) Low density (113) Agriculture (200) Orchards(201) Vineyards (202) Pastures (203) Field Crops (204) Sage Grassland (300) Forest Land (400) High density (401) Medium density (402) Low density (403) Level I represents a general land use and land cover classification. A grid system was placed over air photos to determine the spatial dominance of the categories; at a scale of 1:15,000, when areas met the minimum delineation criterion of 0.6 cm X 0.6 cm, they were classified as distinct categories. Only photos taken from 1994-96 could be ground-truthed for their classifications. Where mixed uses were apparent within the grid and criteria for more than one category were met, the development category took precedence over others, followed by agriculture, and forestry. Development categories were areas of visible human influence characterized by rooftops and streets, or other indicators of population concentrations and impervious surfaces. Agricultural areas were also 42 indicated by human influence, however these were distinguished by regularly shaped fields and a lack of population centres. Forest categories may occur in areas where human influence is visible from air photos, however they are characterized by a spatial dominance of trees vs. rooftops and roads. Sage grasslands are areas covered by natural grasses, forbs and shrubs. Human influence may be evidenced by scattered rooftops and roads, and rangelands may be capable of supporting native or domesticated grazing animals. Like forested areas, sage grasslands are distinguished by the spatial dominance of characteristic vegetative cover relatively undisturbed by development and agricultural indicators. Level II categories are subclasses of level I land use and covers (Table 6). Within the development category were residential, commercial, industrial, and institutional or recreational areas. Residential areas were distinguished from nonresidential areas by smaller and more scattered rooftops, lawns and trees, and regular patterns of closely spaced streets in urban cores. Residential areas were further delineated into high, medium and low density areas (level III). Rooftops and roads that occupied more than 2/3 of a 0.6 cm X 0.6 cm square placed over a 1:15,000 scale photo qualified an area as high density; between 1/3 and 2/3 of the same square as medium density; and less than 1/3 of the square as low density. These criteria were adjusted accordingly for the scales of each set of air photos. Because level I categories were assigned before level II categories, sparse residential land use were grouped within agricultural classes when buildings appeared to be for farm-related housing and forestry in the case of cottages and seasonal homes. Commercial categories typically occurred in three distinct settings: concentrations in central urban cores, strips along major roads, and shopping centres and malls adjacent to residential areas. They were distinguished from residential areas by the sizes of buildings and rooftops, and the relative scarcity of lawns and trees, parking lots and large driveways. Industrial areas were characterized by images of stockpiles of raw materials. Extractive facilities such as quarries and gravel pits were also classified as industrial. Institutional and recreational categories included educational facilities, golf courses, parks and playgrounds. These were characterized by large grassy or gravel fields or associated athletic facilities such as ball and track fields. 43 Within the agriculture category were orchards, vineyards, pastures and croplands or nurseries. Pastures were relatively small areas of grazing land and were commonly interspersed with croplands. Both pastures and croplands appeared uniform in texture relative to orchards and vineyards. Forests were considered for high, medium and low densities. From a 1:15,000 scale air photo, when the crowns of trees occupied over 2/3 of a 0.6 cm X 0.6 cm square, an area was classified as a high density forest. When trees occupied 1/3 to 2/3 of the square, the area was considered a medium density forest. When trees occupied less than 1/3 of the square, the area was categorized as a low density forest. Sage and grasslands were not further delineated into subcategories. The base map data and 1994-96 land use data were compiled using Terrasoft software. However, Maplnfo 4.1 software was used for subsequent digitizing of land use polygons. Trend analyses began with the testing of level I classifications followed by level II classifications only i f significant or strong interactions were found. Where land use was statistically different between years, post hoc tests identified the reaches and times when these differences occurred. Land use trends were then evaluated for the direction and magnitude of change over time. The degree of change was calculated as the difference between percent upland area occupied by a particular land use between 1996 and 1963. 7.2 RESULTS 7.2.1 Review of Land Classification Data To consistently compare the areas allocated for each land use or cover type regardless of the total inland area of the study reach, all classified areas were considered as proportions of the inland area. When all data were pooled, chi-square testing indicated that the data were nonnormal at a significance level of 0.05. Consequently, all significant tests employed nonparametric methods. 7.2.2 Analyses of Spatial and Temporal Trends LAKEWIDE TRENDS In 1963 and 1996, sage grasslands dominated a buffer zone of 500 m around the entire lake (Figure 18). Agricultural, urban developed areas and forested lands occupied progressively smaller areas (Figure 44 18). Sufficient data were not available to test the significance of lake-wide changes between 1963 and 1996, however Figure 18 suggests a general decrease in forested lands, sage grasslands and agriculture, and a general increase in urban development. 100 cu 90 80 o .c 70 (A E 60 o 50 E o 40 o m 30 ro cu < 20 VP 10 0 I Forestry • S a g e Grassland •Agr icu l ture •Deve lopmen t 1963 1996 Figure 18- Dominant Land Use Patterns around Okanagan Lake in 1963 and 1996 SITE SPECIFIC TRENDS In 1963 and 1996, forested lands dominated the 27 study areas and agricultural areas outnumbered urban developed areas and sage and grasslands (Figure 19). Between 1963 and 1996, increases in development and forested lands, and decreases in agriculture and sage grasslands were apparent but not statistically significant at the study areas (Figure 19a). In contrast, increases in the density of nearshore development and docks along the shoreline were significant ( p b u i i d i n g s < 0.000, p d 0 c k s = 0.005; Figure 19b). 45 cp 100 2 80 CO E 70 o *= 60 E o 50 o in CO CD 40 30 •a 20 oo 10 0 u o co 5 D) C o co ° 4 •Fores t ry • S a g e Grassland •Agriculture I Development 3 2 CD CD JD i 1 1963 1996 • 1963 .•1996 Nearshore Buildings Docks Figure 19- Dominant Land Use and Cover Characteristics at the 27 Study Units to a Distance of 500 m from the Shoreline (a) and Directly Along the Shoreline (b) a.) Trends in Urban Development 500 m from the Shoreline Most study units that currently support development also supported development historically (Table 7). Of the 8 study units with development in 1996, only 3 were undeveloped in 1963 (units 29, 37 and 78; Figure 20). Of the 5 study units that were already developed by 1963, only 3 experienced noticeable increases by 1996 (areas 21 , 79, 82; Figure 20). Table 7- Study Units with Development 500 m from Shoreline in 1963 and 1996 SE NE SW SE 21 29 37 78 79 81 82 83 46 S E 40 CD CTl i CO co E 30 CD E Q-o CO t> 20 Q c CD i— Z> CD CD C CD q o N E S W S E • ^ O 5 h - 0 O C 3 > - ^ C N I C O C N c s i o o r - r ^ - o o c o o o Figure 20- Spatial Distribution of Change in Development between 1963 and 1996 (Reaches with asterices were undeveloped in 1963) a.) Trends in Shoreline Development A l l study units that supported shoreline development historically also supported shoreline development in recent years (Figure 21). In 1996, nearshore buildings were found on every study units except 9: reaches 3, 4, 8, 9, 11, 16, and 19 in the southeast quadrant, reach 75 in the northwest quadrant, and reach 80 in the southwest. O f the 18 reaches where buildings were constructed, 13 were undeveloped in 1963. New lakeshore buildings were constructed in recent years at reaches 6, 7, 14, 20, 21 ,31 , 32, 60, 61, 63, 78, 81, 82; Figure 22a). In 1996, docks were found on every reach except 8: reaches 3, 4, 7, 8, 9, 11, and 16 in the southeast quadrant, and reach 75 in the southwest quadrant. O f the 19 reaches where docks were found, 8 were newly developed; no docks were found on these 8 reaches in 1963 (reaches 6, 14, 19, 20, 63, 81, 82; Figure 22b). 47 CD 03 C CD E D. o CD > CD Q CD c "CD o CO 50 40 30 20 10 0 -10 Density of Docks Density of Buildings -2 0 8 10 12 Shoreline Development in 1963 Figure 21- Positive Correlation between Shoreline Reaches Developed in 1963 and 1996 30i CO o> C32 CO CO CT> E 201 XL L _ CD Q . CO cn CO CD CO c CO - C o id 0, SE 4 0 S E CD CT> Oi T-I CO 8 3 0 E s CD Q- 2 0 CO o O Q % B 10i CD CO c CO . c O NE NW SW 1 I.I c o r^Troi - a > T - c N c o h - o - < ^ c o c o c n x - c M c o , , CN CN CN CO CO CO CO CD CO CD h- Is- 00 00 CO * * * * * * * * C O , * 0 0 ' < - O T T - C M C O h - 0 ' i - c O O O O " > O T - C N C O , T - i - CN CN CN CO CO CO CO CD CD CO h- l>- 00 00 00 00 * * * * * # # a b Figure 22- Increases in Shoreline Development between 1963 and 1996 Represented by Increases in the # of Nearshore Buildings (a) and Docks (b) per km of Shoreline (Reaches with asterices were undeveloped in 1963) b.) Trends in Agriculture 500 m from the Shoreline Study units that currently support agriculture are generally the same as units that supported agriculture historically (Table 8). Eight of the 27 study units supported areas of agriculture in both 1963 and 1996: units 32, 33 and 37 in the northeast quadrant; units 78, 79, 80 and 82 in the southwest quadrant and unit 83 in the southeast quadrant (Table 8, Figure 23). In recent years, small areas (<5%) of agriculture were also established at previously forested sites 19 and 20 in the southeast quadrant (Table 8, Figure 23). Large reductions of up to 13% agriculture were observed at units 31, 37, 79 and 80 (Figure 48 23). Agricultural lands were converted to urban areas at units 3.7 and 79 (Figure 20), and replaced by tree cover at unit 31 and sage grasslands at unit 80 (Figure 24). Table 8- Study Units with Agriculture 500 m from Shoreline in 1963 and 1996 CD CO CD 3 o NE < c -10 CD OT ro O ^ -20 I SW ~1 1—•—I I 1 1—•—I 1 1 1 1 • — a>o-v-c\icor^coo>o-*-cMco T - C N j c o c o c o c o r ^ r ^ c o o o c o c o * * Figure 23- Spatial Distribution of Change in Agriculture Among Reaches between 1963 and 1996 (Reaches with asterices did not support agriculture in 1963) a.) Trends in Sage Grasslands In 1963, sage grasslands were found at study units 29 and 33 in the northeast quadrant, and units 78, 80, 81 and 82 in the southwest quadrant (Table 9, Figure 24). In recent years, small areas of sage grasslands (<5%) were established at units 63 and 79 (Table 9, Figure 24). Furthermore, sage grasslands expanded by 17% into agricultural and forested areas at unit 80 (Figure 23, Figure 25). Large reductions of up to 24% sage grasslands were observed at units 29, 33, 81 and 82 (Figure 23) through conversions to urban and forested areas (Figure 20, Figure 25). Table 9- Study Units with Sage Grasslands 500 m from Shoreline in 1963 and 1996 49 _ 20 55 -30 J j ; • o • • • • • • • • • CD CO CO CO CD O T - OJ C M C O C O h - h - C O O O O O * * Figure 24- Spatial Distribution of Change in Sage Grasslands between 1963 and 1996 (Reaches with asterices did not support sage grasslands in 1963) a.) Trends in Forested Lands Study units that currently support large areas of tree cover are closely correlated with units that historically supported large forested areas. Figure 25a and b suggest that changes in forest cover did occur with increases at reaches 31-33 and 81-82, and decreases at reaches 19-21, 29, 79 and 80. Mann-Whitney U-tests had previously indicated that these changes are not statistically significant. Large decreases in forested lands were attributed to urbanization at study units 21, 29, and 79 (Figure 20). Smaller decreases occurred at unit 19 for agriculture and unit 80 for sage grasslands (Figure 23, Figure 24). Increases in forested areas occurred at units 31 and 32 (Figure 23) at the expense of agriculture and at units 33, 63, 81 and 82 at the expense of sage grasslands (Figure 24). 50 S E NE NW S W co c o JZ CO E 100 80 o o m 03 •o c CD I T3 03 03 03 60 40 20 I 1963 n^(Dscoo )T-'^cDcnoT-o )T-(NnsoT-roincoo)Oi-c>in T-i-T-T-(Nt\i(NconncocococosNscooococo I 11996 CD 03 I co CD 03 T3 c CD I T3 0) 03 03 03 O) c co JZ O 30 20 10 -10 -20 CO S E NE NW S W O 1 -CN CN 03 CN CO CN CO CO CO CO CD CO CD o CO co CN CO Figure 25- Spatial Distribution of Forested Lands (a) and Change in Forested Lands (b) between 1963 and 1996 (Reaches with asterices did not support forested lands in 1963) 7.3 DISCUSSION Differences in photo scales and digitizing errors can influence the calculation of land use trends. It estimated that the overall land use calculations could differ by up to ± 10% (Appendix B). 51 Lake-wide data for 1996 revealed that sage grasslands dominated the area 500 m from the shoreline while agriculture, urban development and forested lands occupied much smaller areas. These results contrast with trends observed in the 27 study units where the land is primarily forested. Agriculture, urban development, and sage and grasslands occupied only 20% of all study units. (Figure 26). CD o JZ 00 E o 4— E o o in 100 i 90 80 • 70-60 501 ci) 40 < T3 C TO C dJForestry • S a ge Grassland I [Agriculture • D e v e l o p m e n t Figure 26- Comparison of Lakewide Data to Data Pooled for all Study Reaches 500 m from Shoreline While dominant land use differs very apparently between the lakewide buffer zone and the 27 study units, the direction of change is similar. Development occurred primarily at the expense of agriculture and sage grasslands. The current results confirm past findings that urban areas are increasing and agricultural lands are decreasing (Canadian-BC Consultative Board, 1974; Kerr et al., 1985). 52 CHAPTER 8 - FISH HABITAT USE STUDY To characterize spatial differences in kokanee shore-spawning habitat, habitat features were measured in the field. 8.1 METHODS AND MATERIALS 8.1.1 Source of data The current literature contains information about parameters significant to sockeye and kokanee spawning behavior; however, relatively little information was found to be specific to Okanagan Lake shore-spawning kokanee. Consequently, the literature focused on identifying relevant habitat features while guidance from Okanagan Lake fisheries biologists provided more specific information about characteristics of the habitat features. Two field sampling trips were undertaken to measure the state of current habitat conditions for shore-spawning kokanee. The first took place one week prior to spawning in the fall of 1997. The second was conducted just after fry emergence in the spring of 1998 when water levels in the lake were at their annual low. The difference in water levels between the fall and spring sampling periods was approximately 30 cm (fall = 341.996 m above sea level, spring = 341.702 m above sea level). It was noted that far greater seasonal differences in water levels have occurred over some recent years. Sampling took place at the 22 enumeration reaches identified by the fish abundance analysis (Figure 17) and 5 control reaches around the lake where fish information was unavailable. Five replicate samples were taken at each reach. During the fall sampling, water quality characteristics including dissolved oxygen concentrations and water temperature measured at the water's surface and one meter depth. Corresponding air temperature was also taken at the same time. Because Okanagan Lake kokanee are reported to spawn in waters 1 m and less, underwater photos o f substrate were also taken at this depth. N o substrate samples were taken prior to spawning for measurement. In the spring study, two levels of sampling were conducted. General data sheets were completed for each replicate sample to record human disturbances in the riparian areas and littoral zones, riparian 53 vegetation, littoral macrophytes or periphyton, shore aspect, and the slope of the shoreline at 10 cm and 70 cm water depth. Slope was measured at these two depths because during fall spawning, these areas would be under 40 to 100 cm of water, the water depth reported for the majority of kokanee spawning. To complement these data, aerial photographs and Geographic Information System data were consulted for indicators of shoreline disturbances and the area of habitat beneath 2 m, 5 m, and 10 m of water. Substrate samples were collected at each replicate site. Samples were taken under 10 cm of water and at 10 cm intervals until a surface of bedrock or fine sediment was encountered or a maximum depth of 30 cm was met. The depth of this rock or sediment surface and a visual estimation of the size of material was made in the field. A l l collected samples were transported to U B C labs for analysis. In total, over 3,200 rocks greater than 2 cm in diameter were analyzed. 8.1.2 Analyses Performed Each rock was measured for length, angularity and sphericity, %periphyton, mass, and volume. Length measurements were performed with calipers for long, medium and short dimensions of each rock. Angularity and sphericity were estimated as per Boggs (1995). The surface area of rocks covered by periphyton growth was visually estimated. Each rock was then air-dried overnight and its mass measured to the nearest tenth of a gram. Finally, the volume of water each rock would displace was measured to indicate the surface area it would by itself and in aggregate with other rocks provide to incubating eggs and emerging fry. General shoreline data and specific habitat data were compiled and analyzed for spatial trends. Reach differences were then tested for significance. If statistical differences were detected, post hoc tests were performed to identify homogeneous subsets. 8.2 RESULTS 8.2.1 Habitat Trends Physical, chemical and biological habitat characteristics of 27 study reaches are summarized in Table 10. The compilation indicates that shoreline areas ranged from very shallow (0.7 degrees) with 54 large beach areas (0.34 k m 2 per km of shoreline) to very steep (17.87 degrees) with no beach areas. The average substrate depth was -7.7 cm and ranged from 0 to -20 cm (beneath 10 cm of water). Rock sizes ranged widely from a maximum long dimension of 43.1 cm to a minimum short dimension of 1.6 cm. The mass of rocks averaged 203.6 g and ranged from 1,935.2 g to 5.0 g; their volumes averaged 70.0 ml and ranged from 334.0 ml to 0.2 ml (334.0 cm 3 to 0.2 cm 3). Rock angularity ranged from very angular to round, and the majority of all rocks were low in sphericity. Dissolved oxygen concentrations averaged 9.9 mg/L in water that ranged from 13.0 °C to 16.7 °C at the substrate-water interface one metre from the surface of the water. Rocks at the substrate-water interface (z=-10 cm) were covered by an average of 50 % periphyton cover; coverage ranged from 0 % to 78 % coverage. Table 10- Summary Table of Habitat Characteristics at 27 Study Reaches Variable Mean Max Min N Shoreline Area per km • z= 0-2 m (km 2) 0.01 0.05 0.00 27 • z= 2-5 m (km 2) 0.06 0.34 0.00 27 • z = 5 - 1 0 m ( k m 2 ) 0.03 0.12 0.00 27 Shoreline Slope • z= -10 cm (degrees) 5.2 16.9 0.7 27 • z= -70 cm (degrees) 5.7 17.9 2.1 27 Substrate Depth (cm) -17.67 -10 -30 26 Substrate Size • long dimension (cm) 7.6 22.7 3.1 3254 • medium dimension (cm) 5.5 43.1 2.4 3254 • short dimension (cm) 3.4 7.8 1.6 3254 • mass (g) 203.6 1935.2 5.0 3254 • volume (ml/ cm 3) 70.0 334.0 0.1 3254 Substrate Angularity* S A R V A 3254 Substrate Sphericity + L S L S S 3254 Dissolved O2 (mg/L) 9.9 10.5 8.9 19 Periphyton per rock (%) 50 78 0 2058 * VA= Very Angular, A= Angular, SA= Sub-Angular, SR= Sub-Rounded, R= Rounded, VR= Very Rounded + VS= Very Spherical, S= Spherical, LS= Low Sphericity PHYSICAL CHARACTERISTICS a.) Shoreline Area Shoreline areas beneath 2 m, 5 m, and 10 m of water did not differ distinctly among study reaches (p z o-2m= 0.463, pz2-5 m= 0.463, p z 5 . 1 0 m= 0.463). Quadrants differed significantly in the area of shoreline 55 beneath 5 and 10 m of water (p z 5 .iom = 0.410). Areas associated with the southeast, northeast and northwest quadrants were mutually similar (p= 0.782) and areas associated with the northwest, southwest and southeast quadrants were mutually similar (p= 0.125). Shoreline areas between 5 and 10 m in water depth were distinctly larger in south end of the lake (p= 0.05; Figure 27). S E NE NW S W Figure 27- Spatial Comparison of Shoreline Areas as a Function of Water Depth b.) Shoreline Slope Shoreline slopes did not differ significantly among study reaches (pzio= 0.462, pZ7o= 0.462). In contrast, slopes did differ significantly among quadrants (pz7o= 0.042). Slopes in the northwest quadrant were significantly steeper than slopes in the southwest quadrant (p= 0.050; Figure 28). S E NE N W S W Figure 28- Spatial Comparison of Shoreline Slopes Among Quadrants 56 c.) Substrate Depth Substrate depths did not differ significantly among study reaches (p= 0.462). Substrate depth differed significantly among all quadrants (p= 0.026), however post hoc Tukey tests were not sensitive enough to identify homogeneous subsets of quadrants. From Figure 29, it appears that substrate depths in the northwest quadrant are significantly greater than depths in the southwest quadrant. -13 -14 £ -16 CL CD CD £ -18 5 -19 -20 -21 S E N E N W S W Figure 29- Spatial Comparison of Substrate Depths Among Quadrants d.) Substrate Size Substrate sizes were not significantly different among study reaches or quadrants. Figure 30 illustrates similarities in substrate size for each study reaches grouped according to quadrants. _ 8 o w c CD •o CD O "5) C CD I C CD CD f ] ^ (D N OO O) <- * ( D O ) O r ( J ) T - M n s O ' - n i O ( 0 0 1 0 T - ( < ) T - T - i - N ( N N n c < ) C ) C 0 < O ! D ( D S N S C C C O C O Figure 30- Comparison of Substrate Lengths Among Study Reaches 5 7 Vertical shoreline profiles showed a significant decreasing trend of all substrate size indices with depth (Table 11). Larger substrate rested on top of smaller substrate and gradually decreased in size with depth (Figure 31; Figure 32). Each layer of rock was statistically distinct in size from the next (p< 0.000) with the middle and lowest layers more similar in size distribution than the uppermost layer. Table 11- Kruskal-Wallis Rank Test Results for Differences in Substrate Size Variables Among Substrate Depths Substrate Size Variable p Short Dimension 0.000 Medium Dimension 0.000 Long Dimension 0.000 Mass 0.000 Volume 0.000 z=10cm z=11-20cm z=21-30cm Figure 31- Comparison of Substrate Lengths as a Function of Substrate Depths 58 S E NE NW S W S E NE NW S W a b Figure 32- Comparison of Substrate Mass and Substrate Volume as Functions of Substrate Depths a.) Substrate Angularity Substrate angularity did not vary significantly with study reaches or quadrants. Figure 33 suggests that relatively angular rocks characterized all study reaches. The greatest angularity was observed at sites in the southeast quadrant (Figure 33). c o T t c o o i T - ^ c o c n o T - c j j T - c A i r o h - O ' t - r o i r j T - T - T - T - c > J C N C N C O c r ) C O C O C X > C O C O h -Figure 33- Spatial Comparison of Differences in Angularity Among Quadrants and Reaches Substrate were significantly more angular with increasing substrate depth (p< 0.000; Figure 34). 59 > CD 5 < > II z= 0-10 cm z= 11-20 cm z= 21-30 cm Figure 34- Comparison of Substrate Angularity with Substrate Depth Note: 1= V A = Very Angular, 6= V R = Very Round CHEMICAL CHARACTERISTICS Dissolved oxygen concentrations were not statistically distinct among study reaches or quadrants. Concentrations at all reaches were found to be above B . C . Water Quality Criterion levels of 5.0 mg/L required for developmental stages of fish (Figure 35; B . C . Ministry of Environment, Lands and Parks, 1998). 11 S E NE NW |> 10 CD > CD c CD cn >% X O •o CD > o (/) w b co -3- co cn T - - ^ • C D 0 5 0 T - C 3 > T - C N C O r ^ . O i - C O T - T - T - C N C M C N I C O C O C O C O C O C D C D l"~ Figure 35- Spatial Comparison of Dissolved Oxygen Concentrations Among Study Reaches 60 BIOLOGICAL CHARACTERISTICS The area of periphyton growth on substrate was not statistically distinct among study reaches or quadrants. Figure 36 illustrates that periphyton was observed at all study reaches and that periphyton covered 30 to 60% of most rocks. 60 -I SE ; NE : NW ; SW ll 111 III 11 ill, cm 10 n t I O N 0 0 0 1 r * ( 0 ( » O r < ! ) r - C M n S O r n i O C O C I I O ' - ( 0 r i - i - T - C M C N P i n n c o n i O t O l D N K S C O l D C O Figure 36- Spatial Comparison of Periphyton Cover on Substrate Among Study Reaches 8.2.2 Correlations among Upland Characteristics For more detailed consideration of interactions among fish abundance, land use and habitat features at each reach, the number of parameters to represent the shoreline and habitat indices was reduced using a nonparametric Spearman rank test. Parameters with statistically significant (a<0.05) and strong (r>0.5) correlations were grouped as follows: • bathymetry characteristics- shoreline area, shoreline slope • substrate characteristics- substrate depth; substrate dimensions; mass; volume; number of rocks To summarize, the characteristics derived from the present study for evaluation of interactions with fish abundance and land use patterns are listed in Table 12. 61 Table 12- Habitat Characteristics for Comparison with Fish Abundance and Land Use Indices Index Shore area at z= 0-2 m Shore area at z= 2-5 m Shore area at z= 5-10 m Slope at z= 10 cm Slope at z= 70 cm Maximum depth sampled Medium dimension Angularity Substrate mass Substrate volume Characteristic Indicated Exposure to water movement, area for shore-spawning Exposure to water movement, area for shore-spawning Exposure to water movement, area for shore-spawning Exposure to water movement Exposure to water movement Exposure to water movement Protection from movement, predation, low DO Protection from movement, predation, low DO Protection from movement, predation, low DO Protection from movement, predation, low DO, periphyton growth 8.3 DISCUSSION Chapter 3 provides the background information on which two field studies aimed at gathering data on the spatial availability of kokanee shore-spawning habitat were based. Habitat characteristics of significance to fish include sufficient dissolved oxygen levels; sufficient water movement to facilitate gas exchange; and appropriate substrate cover to protect eggs and developing alevins and fry from predation, dessication and freezing. The data indicate that in Okanagan Lake, shoreline area, shoreline slope, and substrate depths differed significantly among quadrants but not reaches. Substrate size and angularity did not differ significantly among quadrants or reaches. Substrate size decreased significantly with depth and substrate angularity increased significantly with depth. Dissolved oxygen concentrations and percentages of periphyton coverage also did not differ among quadrants or reaches. Dissolved oxygen levels were within B.C. Water Quality Criterion levels for the protection of adult and developing fish. Periphyton covered rocks were found at every study reach with rock surfaces ranging from 30 to 60 % in coverage. A potential source of error in field sampling stems from the difficulty in identifying and returning to reaches between two sampling periods. It was imperative that water quality measurements were taken just prior to spawning to capture the conditions necessary for spawning and that substrate collections be taken during low water periods after fry emergence when much substrate is exposed for assessment. However differences in the appearances of beaches during high and low water conditions were significant and may have resulted in errors in revisiting sampling beaches within reaches. No measures of sampling error from 62 difficulties in replication were made. Another source of error arose from the subjective evaluation of angularity and sphericity in substrate. While Boggs (1991) was consulted for shape and form indices, Boggs recognizes that results from visual estimates are not highly replicable. This source of error was ., reduced by the use of a single experimenter performing all subjective measures. D i l l (1996) suggested that wave action would likely not be able to dislodge eggs and fry located below 10-15 cm of substrate. The average spawning substrate depth analyzed in the current study was 17.67 cm of water with sampling beginning in 10 cm of water. This suggests that at most reaches, at least 7 cm of substrate would be available for the protection of eggs and developing alevins and fry. B u l l and Matthews (1981) reported that shore-spawning kokanee eggs rest on rock or sediment surfaces 7-30 cm below the substrate-water interface. The observation that rock angularity increased with depth may indicate that water movement along surface substrate acts to effectively smooth rock angles. Substrate at greater depths likely experience enough movement to facilitate gas exchange in crevices among rock particles. To truly understand interactions among fish, land use changes and habitat alterations, a multi-year study should be undertaken to assess temporal changes in habitat characteristics. A n alternative to substrate collection and extensive in-field analysis is the digital recording of underwater images for subsequent computer modeling of lengths, form and shape. This would increase the precision of measurements for yearly comparisons. 63 CHAPTER 9 - INTERACTIONS Chapters 6 and 7 demonstrated that spatial trends and changes through time have occurred with respect to fish abundance and land use activities. Chapter 8 discussed spatial trends in spawning habitat. This chapter seeks relationships among fish abundance, habitat and land use. Furthermore, the possible influences of buffer size on the strengths of interactions measured between fish abundance and land use are examined. Data were available for fish enumeration and land use over time, however no historical habitat data were available for comparison. To partially overcome this problem, the following interactions were examined: • Relationships between recent fish abundance and current habitat characteristics, • Relationships between current land use and current habitat characteristics, and • Relationships between fish abundance and land use in recent years and historically. 9.1 FISH ABUNDANCE AND FISH HABITAT 9.1.1 Methods- Analyses Performed Relationships between fish abundance and spawning habitat characteristics were measured using Spearman Rank correlation coefficients for variables listed in Table 13 among the 27 segments identified in Figure 17. Table 13- Variables Compared for Relationships between Fish Abundance and Habitat Fish Abundance Fish Habitat • Average of last 3 years of data (97, 96, 95) • Shore area at z= 0-2 m • Average of 90s data • Shore area at z= 2-5 m • Shore area at z= 5-10 m • Slope at z=-10 cm • Slope at z=-70 cm • Maximum depth sampled (z m a x ) • Medium dimension at z=-10 cm • Angularity at z=-10 cm • Substrate mass at z=-10 cm • Substrate volume at z=-10 cm 64 ;nificance tests were then applied to identify differences in habitat features: Between reaches that have been inventoried for fish abundance (enumeration reaches) vs. reaches where they have not (control reaches), Among levels of fish abundance defined in Table 14, and Between reaches where statistically significant decreases in fish abundance have occurred vs. reaches where they have not. Table 14- Classification of Fish Abundance per Reach for Significance Testing Class Range in Fish Abundance Very Low 0-24 Low 25-99 Medium 100-499 High >500 9.1.2 Results of Analyses Linear Correlations between Fish and Habitat Variables Significant but weak correlations were found between variables for current fish abundance vs. shoreline slope, substrate depth and substrate angularity (Table 15). Fish abundance appears to be higher where shoreline slopes, substrate depths and angularity are greater (Table 15). Table 15- Significant Spearman Rank Correlation Coefficients between Fish Abundance and Habitat Characteristics Slopes Slopez7o Substrate Depth Substrate Angularity Fish#1997.95 Rho P N +.390 .049 26 Fish#i99o s Rho +.442 +.442 +.486 -.491 P .045 .045 .012 .011 N 21 21 26 26 Differences in Habitat Features between Enumeration and Control Reaches Substrate depth was significantly greater (p= 0.005) and rocks were more angular (p= 0.42) at enumeration vs. control reaches (Figure 37). 65 23 Control Enumerated Control Enumerated b Figure 37- Differences in Substrate Depth (a) and Angularity (b) between Enumeration & Control Reaches Differences in Habitat Features among Levels of Fish Abundance Among enumeration reaches that currently support high, medium, low or very low levels of fish abundance, substrate depth and angularity also differed significantly (pdePth= 0.032, Panguiarity= 0.046). Neither substrate depth nor fish abundance varied systematically with different levels offish abundance (Figure 38). Substrate depth was greatest in reaches that supported medium levels of spawning activity (100-499 fish) and lowest in reaches that supported very low levels of spawning activity (0-24 fish) (Figure 38). Substrate was more angular at enumeration reaches where current fish abundance is high (>500 fish) than reaches where abundance is very low (0-24 fish) (Figure 38). 66 ~ 5 or > II co < M High Medium Low Very Low High Medium Low Very Low Figure 38- Differences in Substrate Depth (a) and Angularity (b) with Varying Levels of Fish Abundance d) Differences in Habitat Features between Reaches with Significant vs. Insignificant Declines Shoreline slope was significantly less steep (p= 0.036) and substrate angularity was significantly lower (p= 0.041) at enumeration reaches where statistically significant declines in fish abundance occurred vs. reaches where they did not (Appendix J ; Figure 39). II co < 4J Insignificant Significant Insignificant Significant Figure 39- Differences in Shoreline Slope (a) and Angularity (b) between Enumeration Reaches with Significant vs. Insignificant Changes 67 9.1.3 Discussion While the literature contains references about the importance of habitat features such as shoreline area, slope, and substrate depth, size and angularity, Spearman Rank Tests indicated only weak relationships between fish abundance vs. shoreline slope, substrate depth and angularity. Correlations suggested that spawning activity was higher where the shoreline was more steep and substrate depth was greater and rocks were more angular. These interactions were corroborated by significance tests among study reaches. Substrate depth and angularity were found to be greater at enumeration reaches than reaches where spawning activity was so rare, they were not inventoried by fisheries staff. Substrate depth and angularity were also found to differ significantly among reaches that support high (> 500 fish) vs. very low (0-24 fish) levels of spawning activity. Furthermore, shoreline slope and angularity were found to be significantly greater at enumeration reaches where statistically significant fish declines were observed than enumeration reaches where they were less obvious. These three habitat indicators were the only ones that showed a partially consistent pattern with fish abundance, with substrate depth being the most consistent followed by angularity (Figure 40). Figure 40- Interactions between Fish Abundance and Habitat Characteristics (Dotted arrows indicate interactions determined by Mann-Whitney or Kruskal-Wallis Rank Tests) Some reasons for the weakness of relationships include the low number of enumeration reaches compared and the non-normal distribution of many habitat variables. The Spearman Rank Correlation Test HABITAT CHARACTERISTICS + + FISH ABUNDANCE 68 is a commonly used nonparametric measure of correlation between two ordinal variables (SPSS, 1998; Zarr, 1996). A s a nonparametric test, only the rank orders o f data are considered for calculating the correlation coefficient and its significance. For variables such as substrate angularity where the data were discrete and most values were between 1 and 3, only a small number of ranks were available for consideration. While the test does not assume that the population of data follows a normal distribution, it does assume that the sample distribution is free from outliers and that the variables compared observe a linear relationship (SPSS, 1998). If outliers were in the data set or i f the variables followed a trend that was not linear, the Spearman Rank Correlation Test would be weak in testing interactions between variables. Finally, while statistics is a means to objectively determine the mathematical significance of trends, it does not define biological or physical significance. Although one test indicates that correlations are weak between variables, other significance tests may corroborate or refute the findings when these tests are designed ways that measure more subtle or specific aspects of the variables. This was the case in the current study: while Spearman Rank Correlation Tests indicated only weak interactions among variables, Mann-Whitney U-tests and Krusal-Wallis Rank Tests which examined more specific and relevant aspects of the data set found significant interactions between fish abundance and habitat variables. Other possible reasons for the weak interactions are confounding factors that influence fish numbers. Kokanee spend a relatively short period of their life cycle in the shore habitat. While the current study relates only shore-spawning activity with habitat, egg incubation, alevin development and fry emergence are also important life stages along the lakeshore that may influence fish abundance. Furthermore, conditions in pelagic regions of the lake during other life stages of kokanee may also be responsible for kokanee decline. The contributions of other life history factors on the reproductive success of kokanee are beyond the scope of this study, however they are currently being examined by other studies of the Okanagan Lake Action Plan. Controlled experiments would be needed to clearly establish causative relationships among spawning activity, habitat conditions and fish numbers. 69 9.2 L A N D USE ACTIVITIES AND FISH H A B I T A T 9.2.1 Methods- Analyses Performed Two levels of analysis were performed to assess interactions between land use and habitat characteristics. First, Spearman Rank Correlations were calculated for variables listed in Table 16. Next, Mann-Whitney U-tests were applied to identify habitat variables that differ between reaches where a particular land use type is present or absent. Table 16- Variables Compared for Relationships between Land Use Activities and Habitat Indices Land Use Activities Area of urban development in 1996 Area of agriculture in 1996 Fish Habitat • Shore area at z= 0-2 m • Shore area at z= 2-5 m Area of sage and grasslands in 1996 • Shore area at z= 5-10 m • Area of forested lands in 1996 • Number of roofs in 1996 • Number of docks in 1996 • Slope at z=-10 cm • Slope at z=-70 cm • Maximum depth sampled (zmax) • Medium dimension at z=-10 cm • Angularity at z=-10 cm • Mass at z=-10 cm • Volume at z=-10 cm 9.2.2 Results of Analyses a) Linear Correlations between Land Use and Habitat Features The results of Spearman Rank Correlation Tests are listed in Table 17. The density of docks along the lakeshore and the percentage of agriculture in each study area were found to be significantly and strongly negatively associated with shoreline slope and positively associated with substrate angularity (Table 17; Figure 41). The greater the number of docks for each kilometer of shoreline, the more gradual the slope and more angular the substrate (Figure 41). Similarly, the greater the area of agriculture for each square kilometer of study area, the more gradual the slope and more angular the substrate (Table 17). The area of agriculture and sage grasslands was also found to be negatively associated with substrate depth (Table 17). The more agriculture or sage grasslands in a study area, the more shallow the depth of substrate (Table 17). 70 Table 17- Significant Spearman Rank Coefficients between Land Use and Habitat Characteristics Shoreline Shoreline Substrate Substrate Slope7io Slope Z7o Depth Angularity Nearshore Buildings Rho P N +.495 .010 26 Docks Rho -.479 -.608 +.583 P .028 .003 .002 N 21 21 26 Agriculture Rho -.515 -.550 +.528 P .017 .004 .006 N 21 26 26 Sage Grasslands Rho P N -.512 .007 26 in CD CD i_ D) CD •a 80i 601 CD 8-401 CO CD C 1 20] o JZ CO 0 I to • • • OH > 5 ll CD II 5 3 TO c < 1 -5 0 5 10 15 20 25 30 35 40 Current Dock Density -5 0 5 10 15 20 25 30 35 40 45 50 Current Dock Density Figure 41- Interactions between Dock Density and Shoreline Slope (a) and Dock Density and Substrate Angularity (b) b) Differences in Habitat Features with Presence/Absence of a Specific Land Use Table 18 lists habitat characteristics that differed significantly among study units with the presence/ absence of a specific land use. The area of shoreline between 0 and 2 m of water was significantly greater where nearshore development and dock construction occurred (Table 18). Similarly, the slope of the shoreline was more gradual where shoreline development and agriculture occurred (Table 18; Figure 42). Substrate depths were lower as substrate layers were more shallow where agriculture and sage grasslands were present (Table 18). Furthermore, surface substrate angularity was less angular 71 (1= VA= Very Angular, 6= VR= Very Round) where signs of human activity such as agriculture, nearshore buildings and docks were present (Table 18; Figure 43). Table 18- Significance between Habitat Features and the Presence/Absence of Specific Land Uses p(Shoreline p(Shoreline p (Shoreline p (Substrate p (Substrate Area2) Slopes) Slope770) Depth) Angularity) Nearshore Buildings 0.039 0.037 0.017 Docks 0.022 0.017 0.005 0.000 Agriculture 0.039 0.016 0.013 Sage Grasslands 0.011 Absent Present Nearshore Buildings along Shoreline 20 w CD CD cn CD T3, CD C L O CO CD c a> i _ o .c CO Absent Present Docks along Shoreline Absent Present Agriculture in Study Area c Figure 42- Shoreline Slope as a Function of the Presence/ Absence of Nearshore Buildings along the Shoreline (a), Docks along the Shoreline (b), and Agriculture in the Study Area (c) 72 > 5\ II co < Absent Present Nearshore Buildings along Shoreline Absent Present Docks along Shoreline > 5\ n CD < > Absent Present Agriculture in Study Area c Figure 43- Substrate Angularity as a Function of the Presence/ Absence of Nearshore Buildings (a) and Docks (b) along the Shoreline, and Agriculture in the Study Area (c) 9.2.3 Discussion Spearman Rank Correlation Tests revealed strong interactions between land use indicators such as dock density and the areas of agriculture and sage grasslands, and habitat variables including shoreline slope, substrate angularity and substrate depth. These findings were corroborated by Mann-Whitney U-test results, which further revealed interactions between shallow shoreline areas and nearshore development. Shoreline areas beneath 0 and 2m of water were significantly larger where nearshore development occurred. Shoreline slopes were also more gradual and substrate less angular where human activities such as boating and agriculture occurred. Finally, substrate depths decreased with increasing areas of agriculture and sage grasslands. Figure 44 summarizes these interactions. 73 LAND USE/COVER HABITAT CHARACTERISTICS Figure 44- Interactions between Land Use and Habitat Characteristics These results were not unexpected. Human settlements favor easy access to water: development, recreational activity and agriculture are more likely to occur in larger sheltered shallow water areas and where the shoreline slopes gently. In these areas, substrate are likely to pack more evenly, producing an "impervious" layer of substrate closer to the water-surface interface. Where shoreline development occurs, artificial substrate may also be used to stabilize banks or slope the shoreline more gradually, resulting in substrate that are less angular. It was expected that the area of development 500 m from the shoreline would have stronger interactions with habitat variables. Reasons for weak correlations include limitations of the statistical procedures described in Section 9.1.3. The study results may also reflect inaccuracies in the basic research assumptions. It was assumed that an areal index of urban development 500 m from the shoreline would effectively indicate most point source and non-point source impacts despite regional differences that climate, hydrology and geology can exacerbate or mitigate. While urban development 500 m from the lakeshore may cause subtle but chronic effects on habitat, its area will not directly impact fish habitat. Instead, associated activities such as drainage from storm sewers, discharge of industrial effluent, and runoff from agricultural fields have a greater potential for direct impacts on fish habitat. These activities 74 were assumed in the areal index of land use. That is, the larger an urban developed area, the more storm sewers or effluent pipes drain into the lake. Similarly, the larger an agricultural field, the more pesticides and fertilizers runoff into the lake. Future studies that involve a wider suite o f land use indicators wi l l likely show stronger interactions between urban development and habitat characteristics. A limitation of the current study was that only one year of habitat data were available for comparisons with land use data. Therefore, causative relationships suggested by temporal trends between changes in land use and changes in habitat characteristics could not be discerned. Furthermore, changes in human land use could not be clearly distinguished from natural differences in hydrology and geology in their effects on habitat characteristics. 9.3 FISH ABUNDANCE AND LAND USE ACTIVITIES 9.3.1 Methods- analyses performed Since both current and historical data were available for fish abundance and land use variables, it was possible to examine for interactions throughout the period from 1971 to 1996. Four levels of analyses were conducted. Spearman Rank correlations were calculated for variables listed in Table 19 to identify linear relationships between spawning activity and land use. Table 19- Variables Examined for Relationships between Fish Abundance and Land Use Activities Fish Abundance • Average of 1st 3 years (73, 74, 75) • Average of last 3 years (97, 96, 95) • Average of 70s • Average of 90s • Difference between 1 s t & last 3 years • Difference between 90s & 70s Land Use Activities • Area of urban development in 1996 and 1971 • Area of agriculture in 1996 and 1971 • Area of sage and grasslands in 1996 and 1971 • Area of forested lands in 1996 and 1971 • Number of roofs in 1996 and 1971 • Number of docks in 1996 and 1971 • Difference between/ 1971 & 96 urban dev't data • Difference between 1971 & 96 agricultural data • Difference between 1971 & 96 forestry data • Difference between 1971 & 96 forestry data • Difference between #roofs in 1996 & 71 • Difference between #roofs in 1996 & 71 75 Significance tests were applied to all current fish abundance variables to determine whether they differ: • Between reaches that differ in the presence or absence of a particular land use type, and • Among reaches that differ in whether a particular land use type increased, decreased or remained the same. Significance tests were also applied to all land use variables to identify those that differ: • Among various levels of fish abundance defined in Table 14, and • Between reaches where statistically significant decreases in fish abundance have occurred vs. those where they have not. 9.3.2 Results of Analyses a) Linear Correlations between Fish Abundance and Land Use Significant (ot<0.05) and strong (rho> 0.50) correlation coefficients are summarized in Table 20. Current fish abundance was negatively associated with current and historical areas of agriculture and sage grasslands, and positively associated with historical areas of forested lands (Table 20, Figure 45). The more agriculture or sage grasslands associated with a shoreline reach, the fewer fish currently spawn in that particular reach. The more forested land is associated with a shoreline reach, the greater the current spawning activity at that reach (Figure 45). Historical levels were also associated with past areas of sage grasslands (Table 20). Changes in fish abundance were positively correlated with areas of sage grasslands in the past and present (Table 20). Changes in fish abundance were also negatively correlated with current areas of forested lands (Table 20, Figure 46). Greater declines in spawning activity were associated with sites that always supported less sage grasslands and more forested lands (Figure 46). 76 Table 20- Significant (oc< 0.05) and Strong (|rho|> 0.50) Spearman Rank Correlations for Fish Abundance vs. Land Use Indices Current Fish#s Historical Fish#s Changes in Fish#s Current Land Use Last3Yrs 90s lst3Yrs 70s ls,-last 3Yrs 1970s-90s • %Development in 96 • %Agriculture in 96 • %Sage grasslands in 96 -0.654 • %Forested lands in 96 • #Rooftops in 96 #Docks in 96 Current Fish#s Historical Fish#s Changes in Fish#s Historical Land Use Last3Yrs 90s lst3Yrs 70s lst-last 3Yrs 1970s-90s • %Development in 71 • %Agriculture in 71 -0.510 -0.619 • %Sage grasslands in 71 -0.665 -0.693 -0.611 -0.580 +0.579 +0.551 • %Forestedlandsin71 +0.505 +0.510 • #Rooftops in 71 #Docks in 71 Current Fish#s Historical Fish#s Changes in Fish#s Changes in Land Use Last3Yrs 90s lst3Yrs 70s lst-last 3Yrs 1970s-90s • ADevelopment (71-96) • AAgriculture (71-96) • ASage grasslands (71-96) • AForested lands (71-96) • ARooftops (71-96) • ADocks (71-96) -0.511 -0.680 -0.587 -0.569 +0.559 +0.548 +0.524 +0.543 -0.553 -0.561 3000-co o c CO TD C ZD < 2000-0 L _ 1_ ZD O 1000-20 40 60 • For(71) J i A For(96) 80 100 Figure % Forested Land in Study Area 45- Current Fish Abundance vs. Forested Lands 77 CD I -3000 T3 E -6000 < m -9000 0 -12000 co c J= -15000 O -18000 20 40 60 80 100 Current % Forested Lands Figure 46- Changes in Fish Abundance vs. Forested Lands b) Differences in Fish Abundance with the Presence/ Absence of Specific Land Uses There were significant differences in current fish abundance with the presence of all land use and cover types except forested lands. Where development was associated with lands 500 m from the shoreline or nearshore development directly along the lakeshore, fish abundance was significantly lower than reaches where development was absent (Table 21, Figure 47, Figure 48). Similarly, significantly lower fish abundance were associated with inland areas of agriculture or sage grasslands (Table 21, Figure 49). Forested lands were associated with all reaches where fish were present and fish abundance did not differ significantly with forested lands. Table 21- Significance of Differences in Fish Abundance with Presence/ Absence of Specific Land Uses Presence/ Absence p (Fish#97-95) p (Fish#90s) Development 0.034 0.015 Nearshore Buildings 0.202 0.032 Docks 0.101 0.006 Agriculture 0.187 0.035 Sage Grasslands 0.001 0.001 Forested Lands 0.296 0.222 78 d 100 Absent Present Development in 1996 Figure 47- Current Fish Abundance as a Function of the Presence/ Absence of Development Absent Present Absent Present Nearshore Buildings in 1996 Docks in 1996 Figure 48- Current Fish Abundance as a Function of the Presence/ Absence of Nearshore Buildings (a) and Docks (b) d 1 0 0 Absent Present Agriculture in 1996 Absent Present Sage Grasslands Figure 49- Current Fish Abundance as a Function of the Presence/ Absence of Agriculture (a) and Sage Grasslands (b) 79 Differences in Fish Abundance with Changes in Land Use Figure 50 and Figure 51 suggest that regardless of the land use type, changes in terrestrial activities from 1971 to 1996 were associated with significantly lower current fish abundance (Table 22). In contrast, where no change occurred in a land use type between 1971 and 1996, more fish currently spawn (Table 22). Among study reaches where docks and nearshore buildings increased, fish abundance were not significantly different from those where they remained the same (Table 22). Table 22- Significant Differences in Fish Abundance with Changes in Specific Land Uses Development Nearshore Buildings Docks Agriculture Sage Grasslands Forested Lands 0.002 0.230 0.883 0.001 0.003 0.019 0.002 0.691 0.232 0.000 0.002 0.005 No Change Increase Decrease No Change Increase Development b Agriculture Figure 50- Current Fish Abundance vs. Changes in Development (a) and Agriculture (b) between 1971-96 80 I — I 1 Decrease No Change lnc rease co o co CO CO O No Change Increase a Figure 51- Current Fish Abundance vs. Changes in Sage Grasslands (a) and Forested Lands (b) between 1971 and 96 d) Differences in Land Use with Levels of Spawning Activity Among reaches associated with various levels of fish abundance, the current area of sage grasslands (p= 0.001) and historical areas of agriculture, sage grasslands and forested lands varied significantly (Pagr= 0.022, psag= 0.002, pfor= 0.022). Current areas of sage grasslands were significantly higher at reaches presently characterized by very low (0-24 fish) spawning activity (Figure 52). Historical areas of sage grasslands and agriculture were also significantly higher at reaches now characterized by very low fish abundance (Figure 53a, Figure 53b). Historical areas of forested lands were significantly higher at reaches currently supporting high spawning activity (>500 fish) than reaches characterized by very low fish population (Figure 53c). Changes in land use types did not demonstrate a statistically significant distribution among levels of current fish abundance. 81 High Medium Low Very Low Current Fish Abundance Figure 52- Comparison of Current Areas of Sage Grasslands Associated with High, Medium, Low and Very Low Levels of Current Fish Abundance 16 cn 12 c 9 co 6 CD <" S* 3 ro CO High Medium Low Very Low High Medium Low Very Low Current Fish Abundance Current Fish Abundance 100 •o 80 cu 70 High Medium Low Very Low Current Fish Abundance Figure 53- Comparison of Historical Areas of Agriculture (a), Sage Grasslands (b) and Forested Lands (c) Associated with High, Medium, Low and Very Low Levels of Current Fish Abundance 82 e) Differences in Land Use between Enumeration Reaches with Significant vs. Insignificant Declines Current and historical land use types did not differ significantly between reaches where declines in fish abundance were statistically significant and reaches where they were not. From Figure 54, it appears that in 1996, all enumeration reaches were characterized by more than 60% forested land in each study area and that development and agriculture were not significantly more abundant at reaches where fish declines occurred. The same pattern was found in Figure 55 for distributions of land use in 1971 when areas of development were smaller and areas of agriculture were larger. Changes in land use types were also examined for significant variations between enumeration reaches that demonstrated significant declines and all other reaches. Changes in land use types were not more significant at reaches where reductions in spawning activity were more severe. 100 8 80 co m 60 CO CD < £ 40 ZD CO 20 0 I 100-• FOR • SAG • A G R • DEV 8 11 14 21 31 32 33 37 60 61 63 Reaches with Signficant Fish Decline 3 80 « 6 0 0 < £ 40 -•—» co 20 • FOR • SAG • A G R • DEV 3 4 6 7 9 16 19 20 29 75 78 Reach with Insignficant Decline Figure 54- Comparison of Current Land Use Characteristics at Enumeration Reaches with Significant Declines in Fish Abundance (a) vs. Reaches where Declines were Insignificant (b) 83 100 ^ so CD 6 0 < >. 40 00 20 0 I • FOR • SAG • A G R U-I • DEV 100 £ 80 cn « 6 0 < >. 40 00 20 0 1 • FOR • SAG • AGR • DEV 8 11 14 21 31 32 33 37 60 61 63 Reaches with Signficant Fish Declines 3 4 6 7 9 16 19 20 29 75 78 Reaches with Insignificant Declines Figure 55- Comparison of Historical Land Use Characteristics at Enumeration Reaches with Significant Declines in Fish Abundance (a) vs. Reaches where Declines were Insignificant (b) 9.3.3 Discussion Statistically significant interactions were found between fish and land use variables (Figure 56). Strong negative correlations were found between fish abundance and areas of agriculture and sage grasslands; strong positive correlations were found between fish abundance and areas of forested lands. Accordingly, strong negative correlations were found between changes in fish abundance and current areas of sage grasslands while strong positive correlations were found between changes in fish abundance and current areas of forested lands. Mann-Whitney U-test and Kruskal-Wallis Rank Test results corroborated these findings and further indicated interactions between fish abundance and nearshore development and development 500 m from the lakeshore. Significant tests indicated that fish abundance varied significantly with the occurrence of a particular land use type at each reach. Current and historical fish abundance were significantly lower where development, agriculture and sage grasslands were present and higher where forested lands were present. Similarly, land use activities varied with levels of fish abundance. Enumeration reaches characterized by very low (0-24 fish) spawning activity were adjacent to areas with large spans of agriculture or sage grasslands. Reaches characterized by high (> 500 fish) abundance were adjacent to large areas of tree canopy. Figure 56 summarizes these observations. 84 LAND USE/COVER FISH ABUNDANCE/DECLINE Figure 56- Interactions between Fish Abundance and Land Use Characteristics (Solid lines indicate signficant and strong interactions determined by Spearman Rank tests, dotted lines indicate interactions determined by Mann-Whitney or Kruskal-Wallis Rank Tests) These results were generally expected from the findings of the previous sections on interactions between fish abundance and habitat characteristics and land use and habitat characteristics. In section 9.2.2, it was found that dock density and areas of agriculture are associated with reduced substrate angularity while agriculture and sage grasslands are associated with reduced substrate depths. Shoreline slope, substrate angularity and substrate depths were key habitat features that showed significant interactions with fish abundance. Higher fish abundance was observed at enumeration reaches where the shoreline was more steep and substrate were more angular and extended to greater depths. It can be reasoned that land use trends negatively associated with habitat characteristics that appear to be favored by shore-spawners would also have negative correlations with fish abundance. These trends indicate that interactions between land use and fish abundance may be facilitated by habitat characteristics. 85 / Shoreline \ I Slope J Figure 57- Interactions between Fish Abundance and Land Use Facilitated by Habitat Characteristics (Solid lines indicate signficant and strong interactions determined by Spearman Rank tests, dotted lines indicate interactions determined by Mann-Whitney or Kruskal-Wallis Rank Tests) The weakness of interactions measured between fish abundance and urban development 500 m from the shoreline was unexpected. Several reasons may contribute to this finding. Statistical limitations were described in section 9.1.3. Figure 54 and Figure 55 also offer possible causes for weakness. From these figures, it is apparent that the number of study areas where development occurred is relatively low among all reaches. Consequently, the opportunities for interactions between spawning fish and development activities are low. Furthermore, if interactions are truly facilitated by habitat characteristics, the interactions between the area of inland development and fish abundance should be weak since the interactions between the area of inland development and habitat characteristics were also weak. 9.4 EFFECTS OF BUFFER ZONE WIDTH 9.4.1 Methods- Analyses Performed To investigate whether buffer size affects the strengths of interactions measured between fish abundance and land use, GIS data were rebuffered for all level 1 land uses 100 m from the shoreline. 86 Mann-Whitney U-tests were used to compare areas occupied by development 500 m vs. 100 m from the shoreline. Next, nearshore development and inland development in the 500 m and 100 m buffer zones were compared using Spearman Rank Correlation tests with fish abundance and habitat indices (Table 23). Table 23- Variables Compared for Relationships between Fish Abundance and Habitat Land Use Indices Fish Abundance Current Fish Habitat Current development Current fish#s • Aspect • 500 m from shoreline • Last 3 years of data • M a x depth sampled (z m a x ) • 100 m from shoreline • 1990s data • Slope at z=-10 cm • along the shoreline • Slope at z=-70 cm • Water temperature at z=0 m Historical development Historical fish#s • Water temperature at z=-l m • 500 m from shoreline • First 3 years of data • Medium dimension at z=-10 cm • 100 m from shoreline • 1970s data • Medium dimension at z m a x • along the shoreline • Angularity at z=-10 cm • Angularity at z=-10 cm Change in development Change in fish#s • Mass at z=-10 cm • 500m from shoreline • Difference betw/ lst&last 3years • Mass at z m a x • 100m from shoreline • Difference betw/ 90s & 70s • Volume at z=-10 cm • along the shoreline • Volume at z m a x 9.4.2 Results- Correlations among variables Mann-Whitney U-tests results revealed that the percentages of development 500 m from the shoreline were not significantly different from areas of development 100 m from the shoreline. Significant correlations were found between development within the 100 m buffer zone in 1971 and current fish numbers (Table 24). Dock density was strongly correlated to habitat characteristics. These were discussed in Section 9.2. Table 24- Significant and Strong Spearman Correlation Coefficients among Fish Abundance, Habitat Characteristics and Development Development in 1996 Development in 1971 Change in Development Current Fish#s 500m 100m Roofs Docks 500m 100m Roofs Docks 500m 100m Roofs Docks • 1990s -0.501 Habitat Characteristics • Slope at z=-70 cm • M e d dimension@z=-10 cm • Mass at z m a x • Volume at z m a x -0.608 +0.709 +0.791 +0.808 -0.575 +0.764 +0.764 +0.802 87 9.4.3 Discussion O f all correlations between land use and habitat characteristics, interactions o f dock density with shoreline slope and substrate size variables were the strongest. These findings suggest that development indices 100 m from the shoreline and along the shoreline may be better predictors of fish abundance and habitat properties than development 500 m from the shoreline. Nevertheless, Mann-Whitney U-test results indicate that the percent of development 500 m from the shoreline was not significantly different from the percent of development 100 m from the shoreline. Therefore, the land use indices used in Sections 9.2 and 9.3 should not bias findings in favor of false negative results. 88 CHAPTER 10 - CONCLUSIONS This study examined the possible impact of land use changes on shore-spawning kokanee habitat to explain the decline in kokanee abundance at Okanagan Lake. This chapter w i l l : 1. summarize trends observed in fish abundance, land use and habitat characteristics, 2. summarize interactions among the variables, and 3. highlight the implications of these findings in the form of recommendations. 10.1 SUMMARY OF TRENDS 10.1.1 Trends in Fish Abundance Fish abundance data for shore-spawning kokanee suggested cyclicity of spawning activity as well as recent stresses to kokanee. Cycles indicated the presence of both 3 and 4 year old fish during spawning periods. Shorter cycles in recent years suggested external disturbances on fish abundance. Between 1973 and 1997, the shore-spawning kokanee population decreased by 90.5%. Within each year, spawning activity was most variable in the southeast quadrant. While annual peak counts for reaches in the southeast quadrant were often among the highest for the lake, there were also reaches in this quadrant where no fish spawned. The highest fish counts were reported in 1974 while the lowest were reported for 1993. Over the years, spawning activity decreased more rapidly in the southeast quadrant than any other quadrant. Statistical tests revealed that shore reaches with historically high fish abundance experienced the greatest declines in spawning activity. 10.1.2 Trends in Land Use/Cover Within a 500 m buffer zone around the lake, urban areas were increasing and agriculture areas were decreasing between 1963 and 1996. These results confirm trends reported by the Canadian-BC Consultative Board (1974) and Kerr et al. (1985). The general land use distribution differed between the lake-wide buffer zone and the buffer zone in the 27 sites considered in this study. In recent years, forested lands dominated the 27 study units, while agriculture, urban development and sage grasslands occupied disproportionately smaller areas. In contrast, 89 sage grasslands dominated land use within the buffer zone 500 m from the entire lakeshore followed by agricultural, developed and forested lands. Temporal land use trends also differed between the lake-wide buffer zone and the 27 study units. Lake-wide land use trends 500 m from the shoreline revealed a 9.0% increase in urban development, 2.5% decrease in agriculture, 3.5% decrease in sage grasslands and 3.0% decrease in forested areas. Land use characteristics for the 27 study units indicated that urban development increased by 3.1%, agriculture decreased by 2.6%, sage grasslands decreased by 3.4%, and forested lands increased by 3.4% within the 500 m buffer zone. Only 8 of the 27 study units had significant portions of urban development. Among these 8 units, 3 showed significant expansion, 2 experienced new development and 3 maintained the same proportion of urban development over the 33 year period examined in this study. 10.1.3 Habitat Comparison In Okanagan Lake, shallow shoreline areas, shoreline slopes, and substrate depths differed significantly among quadrants but not reaches. Substrate size and angularity, dissolved oxygen concentrations, and the percentage of periphyton coverage over surface substrate did not differ significantly among quadrants or reaches. Shallow shoreline areas between 5 and 10 m of water ranged from 0 to 0.12 k m 2 per length of shoreline. Larger areas were located in the south end of the lake. Shoreline slopes ranged from 2.1 to 17.9 degrees with steeper slopes in the northwest quadrant of the lake and more gradual slopes in the southwest quadrant of the lake. Substrate depths varied from 0 to 20 cm and averaged 7.8 cm beneath 10 cm of water. Substrate depths were lowest in the southwest quadrant and highest in the northwest quadrant. Historic habitat data were not available to describe temporal changes in these habitat characteristics, nor assess the effects of habitat changes on fish abundance over time. 10.2 SUMMARY OF INTERACTIONS 10.2.1 Fish Abundance and Habitat Characteristics Steeper shoreline slopes, greater substrate depths and greater substrate angularity characterized enumeration reaches associated with higher current spawning activity. Greater substrate depths and greater 90 substrate angularity also characterized control reaches where reports o f spawning activity were rare and enumeration reaches that have not experienced significant declines in fish abundance. Since historical habitat data were not available, it was not possible to describe temporal changes in these habitat characteristics, or assess the effects of habitat changes on fish abundance over time. 10.2.2 Land Use and Habitat Characteristics There was a significant trend between shoreline slope and selective land use. The more gradual the slope of the shoreline, the higher the amount of agricultural land use in the 500 m buffer zone and the greater the density of docks along the shoreline. The maximum depth to which substrate could be sampled was also lower at sites with more docks. Historic habitat data were not available to assess the effects of land use activities on habitat characteristics. 10.2.3 Fish Abundance and Land Use The area of development, agriculture and sage grasslands was statistically lower where fish have been observed to spawn. The areas of development, agriculture, sage grasslands and forested land did not differ significantly between sites where statistically significant declines in fish have occurred vs. sites where significant decline have not occurred. Interactions between fish abundance and land use may occur through pathways involving common habitat variables. Habitat properties that both fish abundance and land use activities interact with are shoreline slope, substrate depth, and substrate angularity. It is reasonable to expect that shoreline slope, substrate depth and substrate angularity are influenced by land use changes and in turn, affect the attractiveness of spawning habitat to fish. 10.3 RECOMMENDATIONS a) The current study evaluates only the spatial distribution of habitat resources around Okanagan Lake and assumes that these resources are the most important in the selection of shore spawning habitat. Because only one year of habitat data were available, it was not possible to assess the temporal variations of fish abundance with historic changes in habitat characteristics. Alterations in habitat 91 characteristics as a result of changes in land use activities could not be demonstrated over time; nor could the assumption be validated that chosen habitat characteristics were sensitive indicators of spawning fish abundance. To better understand interactions among fish, land use changes and habitat alterations, habitat characteristics such as shoreline slope, and substrate depth, size and angularity should be monitored every 3 years and compared with tish abundance and land use data. b) The current study determined that land use indicators such as the number o f shoreline docks and rooftops are more strongly related to habitat than the areal indices of development. This is not to imply that the extent of development within a larger buffer zone has less influence on habitat change. It merely recognizes that indicators with direct impacts on littoral zones are more sensitive to habitat change than abstract indicators. More direct linkages between habitat characteristics and land use indicators such as the number of storm drains emptying into the lake, the area of impervious surfaces within an area of the shoreline, and land use directed water level fluctuations should be explored as these likely facilitate better linkages between fish abundance and habitat. c) For decades, water management has almost solely been directed to the protection of land uses. Due to the climate and hydrology of the Okanagan region and historic desire to populate the region, flood and drought management for municipal and irrigation needs have been the primary considerations for lake level management. Greater research efforts should be devoted to determining how changes in lake levels affect spawning habitat conditions. Furthermore, current water management practices need to reflect the already existing body of knowledge on the negative impacts of lake level fluctuations on fry emergence success. d) Interaction analyses revealed differences between lake level trends in land use activities and activities at the 27 sites considered in the present study. The 27 study sites were specifically selected to represent sites where the most comprehensive set of spawning abundance data exists and likely have the most influence on spawning conditions. However, eggs, alevins, fry and possibly juveniles also occupy shoreline areas that may be impacted by riparian land use activities. The current study focused on the 92 impacts of land use and shoreline habitat conditions on spawning fish abundance. Further studies should examine the effects of land use and shoreline habitat conditions on other life history stages associated with the shoreline. e) Interactions between kokanee abundance, land use and habitat characteristics were demonstrated in the current study. However, complexities in spawning site selection and the impacts of a wide variety of factors unrelated to shoreline habitat changes and spawning complicated the interactions, causing some dampening of possibly strong relationships. These factors may include low lake productivity, overwhelming competitive pressures from mysid shrimp, or overwhelming predation pressures from other fish and fowl on the fitness of kokanee. Some of these variables are now being studied through the Okanagan Lake Act ion Plan. The current study should be revisited when results of investigations on other factors affecting the abundance of shore-spawning kokanee become available for integration. 93 CHAPTER 11- REFERENCES Armour, C . 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Upper Saddle River, New Jersey: Prentice-Hall, Inc. 102 APPENDIX A- DATA SUMMARIES FOR PEAK ANNUAL FISH ABUNDANCE PER SITE Variable Description SITE Number to identify each M E L P enumeration reach Q U A D Quadrant of lake site is located C O N E X P Control vs. Enumeration site FISH73 Peak fish abundance in 1973 FISH74 Peak fish abundance in 1974 FISH78 Peak fish abundance in 1978 FISH79 Peak fish abundance in 1979 FISH83 Peak fish abundance in 1983 FISH85 Peak fish abundance in 1985 FISH86 Peak fish abundance in 1986 FISH87 Peak fish abundance in 1987 FISH88 Peak fish abundance in 1988 FISH89 Peak fish abundance in 1989 FISH90 Peak fish abundance in 1990 P E A K 9 1 Peak fish abundance in 1991 P E A K 9 2 Peak fish abundance in 1992 P E A K 9 3 Peak fish abundance in 1993 P E A K 9 4 Peak fish abundance in 1994 P E A K 9 5 Peak fish abundance in 1995 P E A K 9 6 Peak fish abundance in 1996 P E A K 9 7 Peak fish abundance in 1997 n Number of data points 103 o K ) K ) K ) K ) K ) K ) U i 4^ u> K J K ) 1—' O NO oo —] ON U i 4^ O J K J 1 — ' © NO 00 ON U l 4^ O J K J Zi 2! oo 00 00 oo 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 tn ffl m ffl ra m ra ra w ra ra ra to m ra ra ra ra ra m ffl ra ra ra ra ra ra m m ra m ra ra ra ra ra ra ra ra ra w ra m ra m ra ra ra ra m m m 3 3 - 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 a 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 n> 3 rt ro 3 n> 3 CO 3 f t 3 cs 3 CD 3 ft 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt 3 rt rt ft *-t »-t - j - j >-t »-t >-t •-t *n >-t ~t ^ i ^ i p fa p p P P to P SO SB SB so SB SB SB to P p p P p p P P p P o O o o O O O o o o o o o o o O O o o O o o o O o O 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 K ) K J O J K ) U i K J O J oo O J K J Ln K> U l U l U l 4^ U l U l © © U l o U l U i © o © O © O O U l U l U l o © © © © © © © © J> o © © © © p—' O J o o o o O o o o © © © o O o O © © © © © © o © U l © © , , K ) 4^ O J K J U l O J K ) O J J> NO 4^ ON O J J> 00 © ON O J K J ON U l U l ^— ~ J LO o 00 00 O J O o © o © U i © ON ON K J © NO J> 4^ U l —] o o o O o © © © © U i o U l U i U l O O © © © O o U i O o o o o o © © © © © o o o o © O © © © o o O J _ J > K J O J _ J> J> O J K ) - J K ) J>. 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NO NO 4^ O J 00 U l 00 O J 00 K J I—* ON NO 4^ ON Ln U l O o o © © © © o © K J U i © © © o - J J > © o o O O o o o © © U l o © © © U i © © © U l o © U i o o © K ) U l O J ^ K J O J _ _ K J © OO K ) J> ON U l U l U l 4^ J> O J NO 1—» NO o © o © © © © U l U i O © U i © © © U l © K ) O o o o o © U i © © © o © o O © o © © o o o o © K ) O J , , K J O J O J NO oo —1 NO J > O J 4^ OO O J oo K J K J K J —] —1 K ) U l © © © o o © © © U l K J © U i © U i O J © Ln U l o o o o © o o o © U l © © U i © © © U l © © © o © © K ) ON OO 4^ K J 4* O J O J O J U i - J © —1 U l O U l U i U l © O o o o © © © © © © © U l © © © © © © O © © © © K ) NO 4^ U i K J O J U l K ) 00 K ) O J ON ON ON K J U i »—' ON ON 00 ON oo ON O o © © © © © © © © U l © U l - J K J © U l K J U l U i O O o O o o O © © © © © © © © © © © U l © U i © © U l o o _ K> K ) O J K J o O J 4^ NO O J 00 O J 00 K J K J —1 © o o O o O © © © o © U l © © © o © © © © © o  o  o o O o © © © o o © K J © © © © © O © © © © © K ) _ _ 4^ K ) K ) , K ) o O J oo 00 K J O O J U l oo o K ) K J U l © U l © © U i U l o © © o U l © K J © o o o O U i o © © © © © © o o © © © © © U i K J © K ) 4*-4^ O Ln o o o o o © © © © o © o o O o o © © © o © O o © —} —] O J U l ^ J O N ~ ~ J ^ J O N 0 0 0 0 ^ J 0 0 00 ^ a 0 0 0 0 0 0 0 0 0 0 0 0 ~ J - ~ J O N U l o U l u i U i U i 4^  4^ - 4^-to O NO VO 00 4^  4^  O N U i Z Z Z z z Z Z Z Z Z tn tn 3 3 c c 3 3 ro co tn tn tn tn 3 3 3 3 CO CB CD CO ^ *-t *1 »-t tn tn 3 3 c c 3 3 CO CO tn tn 3 3 0 c 3 3 CO CO p P f!3 p p p p p o o 3 3 to 4*. U i o o o o O O O 3 3 3 O I O O U i © © VO o U i o o o o o U l o o o o 3 3 — U l O U l O o O O K J i— ~ J — ON O O o O O VO o o to o o o o o o o o 3 3 o ~o O U l o o L O to — L O U l O O o to O O o o o o ~ J ON O U l o o o VO VD o o co o o K J O N to U l O oo O N U l o o o o o o K J U l o L O - J I O U l L O o o o - J N J U i U i — U i J> U i o o o K J u o o U l U l u o o o Ul O O O O o o o U l J> O U i O O O o o o o to Ui o V O O N J> L O V O V O — J>. L O L O L O L O L O L O L O L O L O L O K J to K J to L O K J K J o V O oo O N U i L O to o V O 00 O N Z z z z z z z z z Z z z z Z z z z z tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn tn 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 c c c c c c e c s c 3 c d c 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 CO CO CO CO co co CO CO CO CO co CO CO CO CO CO CO co CO -1 p p p p P P p P p p p p p p p p P p p o o o o O O o o o o o o o o o o O o o 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 ( , K J v o H - U l U l ^ U l U l o U i —1 U l to L O to - J U l o U l ~ J U l O L O o o o o o U l o o o U l U l o o o U l o o o o o o o o o o o o o o o o o o o o o o ^ to to _ H _ U l U l J> • J> L O ^) L O V O o U i V O — J o U l N O 00 V O - J L O U l 00 o J> U l J> V O V O 00 L O 4^  U l U l U l U l o J > U l o o U l to o U l o o u U l O o o o o o o o o o o o U l o o o o o o O o J> to to to O N to O N 4*. —] J> v o K J u o o o o o o o o O o o o o o o o o o o o to to U l L O to 4^  to V O U i O N 4^  v o J> L O 4^  O N U l U l U i U l o U l u U l o o U l U l o U l U l o U l o o o o o o o o o o o o o o o o o o to L O to t , , oo o to »—' L O J> to V O U l N J U l o U l U l K J U l o o o U l o U l o o o U l o o o K J L O o to L O K J L O to O N O N oo U l to oo oo —i o o U l U l U l o o U l o O O U l to L O - J U i I O o 1—1 U l o U l o to U i U l U l o o U l o o o o o o O N o o o U l U l U l o o u L O to J> . 4^  4^  L O U l —1 to o oo J> L O L O U l o - J to to o to L O to to to -o U l o O U l U l U l U l o U l U i o o o U l O U l U l U l U l o o o o o o -o L O L O oo O N L O to L O 4* J> 1—-1 oo V O to - J *—> L O oo O N O o o to o o to u o U l U l U l to -0. o o U l o o o o o U l o o u o o o o o u U l £ to J> U l 00 L O to NO to H -L O V O L O oo v o v o U l L O U l O N oo ~ J U i O o o U l o 1—• o o U l o 4^  O U l U l o O o o o o o o o o o o o o o o o o o o U l ^ L O L O U l L O oo H-> K J o U l o o ~ J o o K J O U l o o o o o o o o o o U l U l o o U l U l o o o o V O 4>> U i U l oo o o o o o o o o o o o o o o o o o o o ^ to to L O —i o U i O to to o U i o o o o o o O U l o U l to _ L O u L O ~ J O N o o o o o o o o o o U l o O o o o - J o O N L O L O to O N o o U i to O N to o O N o o o o o o U i o o o o o o o o o o o o o o to to L O to U l L O to I—-i 00 V O to to ^ o V O o L O SO U l U l o U l o U i o o o o o o o U l •o o o o o o o o o o o o o o o o o o o o o o to o o o o o o o o o o o o o o o , , _ L O L O o J> oo O N o 1—1 00 V O - J o o U l o o o K J o o o U l o o o o o o o o o o o U l o o u o o U l O N O N O N U l U l L O L O U i 00 00 O N O N -o o O N ^ J O N U l J > - O J K J ' — O N 0 0 0 - J 0 \ U l J > - 0 J ON ON K J i— ON O l U i O N O O O U l U l ~ J O N U l U I U I U l ^ u ffl m ffl ffl ffl ffl m ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl ffl 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 rt rt rt rt rt rt rt rt rt rt rt rt rt rt CD CD CD rt rt rt rt rt CD CD CD rt —i - t - i —t - i - t - t - t -t *1 "1 -t -1 *-t *t co to (O to to £0 to £0 £0 CO CO to to to to Co CO CO CO to to CO CO to o o O o O O o o O o o o o O O O o O o O o O O O O O 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 U i K J , , K J K J K J K J O J K J o o © - J O U l U l ON U l U l U l U i U i o U i o o o U l © o o U l U l O © o o O O O O o o o O O o o o o , , ^_ _^ ON U l ON U l i—> K J J> ON ^1 4^ 4^ K J U i O J ON K J NO U i o o O K J NO o NO J> O o U l U l K J 4^ U l ND NO O J O O U l U l o U l U l U i o o o o o o U l U l o o © O O K J U l U l U l O o O o o o o o O o o o o o o o o o o o O O o o o © K J K J J> 4* © o o U l K J © o o o o O O o o o © K J 4^ U l U i O J U l 4^ U l K J ON o o ON o o K J 0 0 ON NO ON O U l U l U l o U l U i O U l o o o U l © U l o U l o U i o o o o o o o o O o o o o o o o o o o o o K ) K ) K J H -, U l K ) 4^ o o ON NO o 4^ o o K J 1—. K ) - J K> o U i K J o o O J o U l U l U l o o U i o U l U l o o U l O J K J K J _ ON O J K J NO ON K J K J o o o (—. 4^ o O J U i o o o ON U l U l K J U l O o 0 0 U l K J K J o 4^ ND o U l o U l O o o o o © o o o o o o o © U l O i t K ) 4* U i J > O J , , U i O J K ) 4^ o o ~ J o o o K J U l K J »—' 1—' o o o o O o o O o o U l o U i O o © o U l o o o o U l o o O O J ON O J NO 4^ 4^ K J K J . o o ON ON U l - J ON o U i J>. O J 4* 0 0 ND ON O J o K> U l o U l O 0 0 ~ J U i ON O J o K J 0 0 U l K J K J o o o U i o o o o o o U i o O o © U l U i o U i U i o o U l o o O K J O J K ) 42. O J U i 4*. K J , , ON , , ON 4^ U l ~ J O J ~ J O J NO U l O J ON K J NO 4^ ON U l o - J U l NO K J U l O J 1—» o K ) U l K ) K> o o K J U I O K J ~ J o o U l K J - J U l - J —] K J ~o U l o o U i U i o U i U i o o U i o o U i U l o o o U i U l o U i o U i U i U l © U l t , K J NO , , K J K J K J U i K ) NO ON ON o o NO J > NO © K J K J - J ON O NO ON o U l O U l o o o U l U l o o U l o o O o U i U l U l o o o o o o o o o o o o o o o © o o o o o o o o o o © ON K J K J K J 4^ U l o 0 0 U l o O o o o o o o o U i U i o o o o o o o o o o O J U i O J K J o U l o o o o o o o K J O U l U i o o o o o o o o o o U i o o o o o o o o O J - J K ) O J U l U i K> K J ON ON ON o o o o U i o o o o ON o © o o o o o o o o o o 4*. K J K> o o o o o o o o o o o o o O o o o o o o o o o o o o o o © , . U l 4^ _^ „ o O J O J U l NO O J K J o O J ON o o o o U l o o o o U i o o U l o o o o o o o o o o o o o o o o o o o o o o o o ~ O J J>- O J o o o K J U l © o o o o o o o o o o o o o o o o o © o o 4^ O J O J , , o U l o o K J o o o o o o o O o o o o o o © o o o o © o U i o o o 0 0 NO 4^ ON U l U i U i 4^ ON 4^ U l J> U l U l ON 4=> o 4^ o o o APPENDIX B- DATA SUMMARIES FOR LEVEL 100 LAND USE AND COVER CLASSIFICATIONS 500 M FROM SHORELINE Variable Description SITE Number of study site C O N E X P Enumeration site vs. control site C O N E X P 2 Enumeration site where significant change has occurred vs. all other sites D E V 6 3 %Area of development in 1963 D E V 7 1 %Area of development in 1971 D E V 8 1 %Area of development in 1981 D E V 9 6 %Area of development in 1996 A G R 6 3 %Area of agriculture in 1963 A G R 7 1 %Area of agriculture in 1971 A G R 8 1 %Area of agriculture in 1981 A G R 9 6 %Area of agriculture in 1996 SAG63 %Area of sage grasslands in 1963 SAG71 %Area of sage grasslands in 1971 SAG81 %Area of sage grasslands in 1981 S A G 9 6 %Area of sage grasslands in 1996 F O R 6 3 %Area of forested land in 1963 FOR71 %Area of forested land in 1971 FOR81 %Area of forested land in 1981 F O R 9 6 %Area of forested land in 1963, 71, 81 and 96 R 0 0 6 3 Number of lakeshore rooftops per km of shoreline in 1963 R 0 0 7 1 Number of lakeshore rooftops per km of shoreline in 1971 R 0 0 8 1 Number of lakeshore rooftops per km of shoreline in 1981 R 0 0 9 6 Number of lakeshore rooftops per km of shoreline in 1996 D O C 6 3 Number of docks per km of shoreline in 1963 D O C 7 1 Number of docks per km of shoreline in 1971 D O C 8 1 Number of docks per km of shoreline in 1981 D O C 9 6 Number of docks per km of shoreline in 1996 U P L A N D A R E A Area of site 500 m from shoreline 6 3 E R R O R % Margin of error from digitizing 1963 air photos 7 1 E R R O R % Margin of error from digitizing 1971 air photos 8 1 E R R O R % Margin of error from digitizing 1981 air photos 9 6 E R R O R % Margin of error from digitizing 1996 air photos 107 o 00 3.78 ON U i 3.78 NO © o O J © Ln 3.78 O J 00 OO O O O O — J ~ J - J O N O N O N O J O J O J N J N ) >— H — ^— O J N J ^ O N O O O O I O J — © • ~ J O J N J H - . N O > — O N O O N - U ^ N O 00 ~~J O N J > O J Si ^ NO O J 22 N> J>. o o o o o o o o o o © o o o o o o o o © O J o o o o © o © o o o o o o © o © o o o o o o o © o o o ON ON - J © oo Ln Ln Ln NO N J © o Ln OJ N J OJ N J Oh N J OJ OJ Ln ;-0 ON O O ON ^] Ln 4^ ON NO OJ OJ NO N J OO N J N J NO Ln ON © OJ N J o Ln NO © Ln Ln N J J> NO OO N J J> N J J> © N J J > Ln "j> © -0 ON oo o © © © © o © © © © © © o o o o o o Ln o OJ Ln © © o o © © o o © © © © © o o o © © o o © © o I o © © © © © © o o o © o o o o o o © o o o © o o o o o © o © o o © © o o o © o o © o o o I N J y © © b Ln o O O OJ © © © O O © © © © © o o o o o o ON Ln ON © © © © © © J ^ . p— © © © © © © o o © © o o -U OJ i — >° y r © O J ON © 00 - J H -N J O J U U i U i j j U i OJ OJ © NO —1 O O ON OJ OJ N J O O U l © N J J>. N J N J OJ J> oo 'jj> OJ U l NO OJ OJ OJ •j> •j> © NO OJ OJ j>. NO © o © © o o o © © © o o © © o o © © o o © © o o © © o o I o o © © O O © © N J N O © © o o o o o © © © J > i— NO © o o o o o o o © © © o o o NO 00 - J ~ J NO oo -J -o NO 00 - J - J o © o o © o o o © © o o © © o o © © © o o o © o o © © © o o © o o o © o I © © © o o o o o o o o © © o o o © o o o N J N J N J 00 o o o © © o o o © o o © o © o o o o © o o o o o I o © ! ~ O © OJ o o o o o o o © © o o o © o o © © o o © o o o © © o o © © o o o © o | Ln Ln © © O J O © © © 0 0 0 0 © © 0 0 0 © 0 0 0 © o I O ^ J O © © 0 0 0 © 0 © 0 0 © © 0 0 © © 0 o I N J — U l J > U, N J g NO — J —] o © © 0 0 0 © © © 0 0 0 © © 0 0 © © 0 0 © © 0 0 © © © 0 0 0 0 © 0 0 © 0 0 0 © © I © N O OO 00 00 oo LO IO H - © o © •U 4^ N) to © o ^ —1 —1 N O o -O NO O J>. o o 4^ ! - ' O 4^ O 4^ to - O . - J - J 0 N 0 N a N L 0 L 0 L 0 L 0 t O I O N O O O U i O J H - O ^ l O J t O H - N O H - o S o ^ 4 t n ^ > o = - J O N J > W to 4^ Ln LO oo N O © O N O O N oo N O N O OO N O N O N O N O N O to p © to N O to N O O N N O N O Ln O N Ln O N to N O N O o C O o N O N O N O GO O N LO N O O N Ln Ln 00 N O 4^ b to N O OO N O Ln Ln -~s O N Ln O N © 4^ O N to O N Ln oo O N N O N O LO © © © © Ln to bo O N LO LO to to LO ! ~ LO Ln NO to N O <1 O N tO O © 4^ O N 4^ - O N Ln © P° P © L»l OO ON 4^  00 © © © © © O LO NO to H -00 N O o o © © to Ln O O Ln Ln oo to . 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Ln : . 5N ^ © £ — NO . i— 4^ Ln O N © © L, o o o © „ © © © © - IX NO oo p— NO L O to Lo o — o o o o o © o © © o 8 © © © o o o o © © © © © © o o © © © © © © © © © © © © © © o © © 8 © © © © o o © © o o o o © © © © o © © o © o 00 00 0 3 0 0 S 1 ^ 1 - J O I O \ 0 \ W U U U W W M M M B . M . 1 „ O J K J > — O N O O O U i O J i — © ~ J O J K J ' — N O « © N O O N J > . > — ~J ON J> OJ p > - >— © H -t o Oi N » b O N KJ KJ OJ J> J> U i J>. — O O O © P N D ^ O o o o p O NO O N OJ © N O U i KJ H - O O O — © © © O O O O O O O O O O O O © p N O J> O N O N _ N O KJ KJ KJ U i K> O N O N - J KJ © O O O N 0 0 4 ^ 0 N O J N O O N U i K J 4 * . ' - -4 ^ O N U > 6 O O ' J > . U I G J . © O J O N O N O N N O O J O O N O KJ C O 00 KJ U i KJ >— O N N O H - N D • — O N N O O O N O - J K ) J > r 4^ o o O o i U i p o o o o p j> o o o NO © ON o © o © j>. U l U i KJ U i KJ ~J o OJ OO oo ON oo OJ o NO - J o 1—1 KJ K J P U , W K ) Q Q K J p © © p p p pz O b b ^ • ° N o O ° 0 O N ^ OO j £ £3 ~-J U i ~ J OJ 0 0 KJ © © P _fi. 00 © © O K J O © © 4 i O K J U l U i O N K J © ^ © O N V © 0 © Q © © 0 O J > . - -K J ^ O N - O ^ H - O N N O ^ J O O N O © - - - 1 0 0 U > 0 © U > ( _ 3 K J > — . ^ ^ O N 0 0 J > O 3 - - 0 U I O J . O N <->J U l P K J p U i P P 4 i . P P p O o O v n b b i j i b b b © © © © 0 0 © © © © © 4^ ~ O J C N ^ U Q O U U K J H S I I J C A O S O O 4^ O J O N O J '—1 - J KJ © KJ O KJ - J © KJ 00 N O © b KJ U i OJ y*1 OJ OJ OJ OJ U l O N © KJ OJ © © 4^ © © p © O N V © © b J > . O N N O C\ U j j M M si © © © © © © o o "-J 4^ O J ^ © © © ZZ- K J — O J . O N ^ J J - J 1 U l KJ - J o APPENDIX C- GENRAL CHECKLIST FOR INVENTORY OF SHORELINE CHARACTERISTICS AT EACH SITE SITE NUMBER AND REPLICATE TIME START TIME END I. Upland/ Riparian A. Human Disturbances (Checklist- YES/NO unless NUMBER Yes/ No Yes/ No Yes/ No Yes/ No Yes/ No specified): • Buildings (eg. residential, commercial, industrial) • Pavement (eg. roads, commercial area, industrial area, blacktops) • Lawn (eg. tended grassy lawn, golf course, picnic area) • Developed parkland (ie. provincial or municipal park area) • Rowcrop (eg. short herby plants and nurseries) • Pasture (eg. livestock grazing, rangelands) • Orchards and vineyards (eg. apples, peaches, grapes) • Bank stabilizing structures (eg. seawall, riprap, gravel bar, revetments) • Docks (Number) • Boat launches (Number) • Marinas (Number) • Boats (Number) Vegetation/ Cove (Checklist- YES/NO for all appropriate): Yes/ No Yes/ No Yes/ No Yes/ No Yes/ No Coniferous trees Deciduous trees Bushes/ shrubs Grasses Rocks and mosses/ lichen II. Littoral A. Aspect (Measure- compass direction): B. Slope (Measure- distance into lake from water's edge): « At 70cm water depth • At 10cm water depth C. Vegetation (Checklist- YES/NO): Yes/ No Yes/ No Yes/ No Yes/ No Yes/ No • Periphyton • Macrophytes D. Substrate Collection (Collected at substrate depths? Yes/ No unless depth other than surface, 10cm and 20cm used): • Surface • 10cm (if maximum depth <10cm, indicate depth) • 20cm (if maximum depth <20cm, indicate depth) • >20cm (Check Y E S i f appropriate) Dir'n Dir'n Dir'n Dir'n Dir'n Metres Metres Metres Metres Metres 111 

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