POPULATION CHARACTERISTICS of STRIPED BASS ( Morone Saxatilis , Walbaum 1792) in MINAS BASIN and PATTERNS of ACOUSTICALLY DETECTED MOVEMENTS WITHIN MINAS PASSAGE

POPULATION CHARACTERISTICS OF STRIPED BASS ( Morone saxatilis , Walbaum 1792) IN MINAS BASIN AND PATTERNS OF ACOUSTICALLY DETECTED MOVEMENTS WITHIN MINAS PASSAGE

JEREMY E. BROOME

Thesis submitted in partial fulfillment of the requirements for

the Degree of Master of Science in Biology

Acadia University

December, 2014

The examining committee for this thesis was:

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Dr. David MacKinnon, Chair

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Dr. Fred Whoriskey, External Reader

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Dr. Michael Dadswell, Internal Reader

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Dr. Anna Redden, Supervisor

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Dr. Stephen Mockford, Department Head - Biology

This thesis is accepted in its present form by the Division of Research and Graduate Studies as satisfying the thesis requirements for the degree of Master of Science in Biology.

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I, JEREMY E. BROOME, grant permission to the University Librarian at Acadia University to reproduce, loan, or distribute copies of my thesis in microform, paper, or electronic formats on a non-profit basis. I, however, retain the copyright to my thesis.

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Author

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Supervisor

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Date

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TABLE OF CONTENTS

LIST OF TABLES ...... VII LIST OF FIGURES ...... IX ABSTRACT ...... XIII LIST OF ABBREVIATIONS AND SYMBOLS USED ...... XIV ACKNOWLEDGEMENTS ...... XV DEDICATION ...... XVII CHAPTER 1 – General Introduction ...... 1 1.1 THESIS OBJECTIVES ...... 6 1.2 THESIS ORGANIZATION ...... 6 1.3 FIGURES ...... 8 1.4 APPENDIX ...... 9 CHAPTER 2 - Characteristics of Striped Bass ( Morone saxatilis ) angled in the Minas Basin, NS recreational fishery ...... 10 2.1 INTRODUCTION ...... 10 2.2 MATERIALS AND METHODS ...... 14 2.2.1 Study Site Description ...... 14 2.2.2 Field Methods - Angling...... 15 2.2.3 Striped Bass Sampling ...... 16 2.2.4 Notices to Anglers ...... 18 2.2.5 Analysis of Samples and Data ...... 18 2.3 RESULTS ...... 21 2.3.1 Angling Effort and Catch Patterns ...... 21 2.3.2 Population Characteristics...... 23 2.3.3 Recaptures and Movement ...... 24 2.3.4 Population Estimates ...... 26 2.4 DISCUSSION ...... 26 2.4.1 Angling Effort and Catch Patterns ...... 26 2.4.2 Population Characteristics...... 31 2.4.3 Recaptures and Movement ...... 35 2.4.4 Conclusions and Recommendations ...... 39

2.5 TABLES ...... 41 2.6 FIGURES ...... 44 2.7 APPENDIX ...... 51 CHAPTER 3 - Detection range and efficiency of VEMCO acoustic telemetry technology in the hyper-tidal Minas Passage, Bay of Fundy ...... 54 3.1 INTRODUCTION ...... 54 3.2 METHODS ...... 58 3.2.1 Study Area ...... 58 3.2.2 VEMCO Transmitter and Receiver Technology ...... 59 3.2.3 Instrument Mooring Design ...... 60 3.2.4 Receiver and Tag Array Design ...... 61 3.2.5 Array Deployment ...... 63 3.2.6 Array Recovery ...... 63 3.2.7 Data Treatment and Analysis ...... 64 3.2.8 Daily Performance Metrics ...... 65 3.2.9 Model of Detection Efficiency ...... 68 3.3 RESULTS ...... 68 3.3.1 Performance Metrics ...... 68 3.3.2 Performance Metrics Pre vs. Post TISEC Installation ...... 69 3.3.3 Diel Patterns – Detections and Missed Detections ...... 70 3.3.4 Detection Range ...... 70 3.3.5 Model of Acoustic Detection Efficiency with Current Speed ...... 71 3.4 DISCUSSION ...... 72 3.4.1 Conclusions and Recommendations ...... 83 3.5 TABLES ...... 86 3.6 FIGURES ...... 89 CHAPTER 4 - Detection of acoustically tagged Striped Bass across Minas Passage and within the FORCE test area ...... 103 4.1 INTRODUCTION ...... 103 4.2 METHODS ...... 105 4.2.1 Study Area ...... 105 4.2.2 Passive Monitoring of Fish Movements ...... 106

4.2.3 Striped Bass Collection and Tagging ...... 107 4.2.4 Receiver Moorings ...... 110 4.2.5 Mooring Deployment ...... 110 4.2.6 Mooring Recovery ...... 112 4.2.7 Data Treatment ...... 113 4.2.8 Movement Analysis ...... 114 4.2.9 Assumptions ...... 116 4.3 RESULTS ...... 117 4.3.1 Post Tagging Survival ...... 117 4.3.2 General Detection Patterns ...... 117 4.3.3 Temporal Distribution ...... 118 4.3.4 Number of Interactions ...... 119 4.3.5 Spatial Distribution ...... 120 4.3.6 Travel Rate ...... 121 4.3.7 Depth Distribution ...... 121 4.4 DISCUSSION ...... 123 4.4.1 Spatial and Temporal Distribution ...... 123 4.4.2 Travel Speed ...... 126 4.4.3 Depth Distribution ...... 127 4.4.4 Conclusions and Recommendations ...... 130 4.5 TABLES ...... 134 4.6 FIGURES ...... 142 ...... 158 4.7 APPENDIX ...... 159 CHAPTER 5 – General Discussion ...... 164 5.1 FINDINGS AND IMPLICATIONS ...... 164 5.2 RECOMMENDATIONS ...... 168 REFERENCES ...... 172

LIST OF TABLES

Table 2-1. Catch statistics of self-reporting, provincially licensed, Nova Scotia resident, Striped Bass anglers (Data Source: DFO, 1994; 1997; 2003; 2007; 2012; NSDFA, n.d.)...... 41

Table 2-2. Summary table of Striped Bass sampling and tagging efforts and estimated population characteristics for years 2008-2010...... 41

Table 2-4. Distribution of recaptured Striped Bass recovered from all locations by year, relative to year of initial tagging...... 42

Table 2-5. Number of Striped Bass recaptures reported during each survey year by reporting source...... 42

Table 2-6. Distribution of cumulative multiple recapture counts for individual Striped Bass pooled for 2008-2010...... 43

Table 2-7. Striped Bass tag returns, pooled for 2008-2010, indicating location and season of capture. Formatted as in Rulifson et al. (2008)...... 43

Table 2-8. Summary of sequential Striped Bass population size estimates for the immediate area of the Grand Pré tagging site...... 43

Table 3-1. Instrument deployment and recovery metadata for 7 VEMCO VR2w acoustic receiver mooring stations positioned at the FORCE test site within Minas Passage, NS...... 86

Table 3-2. Model specifications for each of 4 VEMCO acoustic tags acoustic receiver mooring stations positioned at the FORCE test site within Minas Passage, NS...... 86

Table 3-3. Receiver detection parameters and mean daily performance metrics for each of 7 moored VEMCO VR2w acoustic receiver stations over 47 days of continuous monitoring...... 87

Table 3-5. Akaike’s second-order information criterion (AICc) of logistic regression models of range test tag detection probability (Detection) in Minas Passage, Bay of Fundy (BoF)...... 88

VII

Table 4-1. Summary of 2010 Striped Bass tagging activities and transmitter specifications, by tagging site...... 134

Table 4-2. Deployment and recovery metadata summary of acoustic receiver moorings placed in Minas Passage, NS during summer and fall 2010...... 135

Table 4-3. The number of tagged Striped Bass, valid detections, and distribution of detections between ebb, flood, and slack (<0.5m/s) tidal stages as recorded at each receiver station during 2010...... 136

Table 4-4. Summary information of Striped Bass (N = 52) detected within Minas Passage, NS..137

Table 4-5. Summary of Striped Bass travel speeds through Minas Passage between the OTN-MPS and FORCE receiver arrays...... 139

Table 4-6. Summary of depth distributions of individual acoustically tagged Striped Bass detected by array. Depth data is filtered for duplicate detections...... 140

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LIST OF FIGURES

Figure 1-1. Native distribution of Striped Bass ( Morone saxatilis ) along the Atlantic coast of North America. (Figure modified from www.aquamaps.org)...... 8

Figure 2-1. Locations of the five known Canadian Striped Bass spawning stocks...... 44

Figure 2-2. Map of the southern portion of the inner Bay of Fundy indicating locations of major water bodies...... 45

Figure 2-3. Daily CPUE (fish/rod/hour) indicated by month during years 2008-2010. Dark grey bars, light grey bars, and white bars represent survey years 2008, 2009, and 2010, respectively...... 46

Figure 2-4. Daily catch per unit effort (fish/rod/hour) relative to daily tidal range (m)...... 46

Figure 2-5. Daily CPUE (fish/rod/hour) indicated by hour of day in which the high tide occurred, pooled for years 2008-2010...... 47

Figure 2-6. Left: Percent frequency distribution of four hook types used to angle Striped Bass in Minas Basin, NS during 2009 (n=205, light bars) and 2010 (n=260, dark bars). Right: Hook styles: A) wide gap worm, B) circle, C) standard (J), and D) treble...... 47

Figure 2-7. Length frequency of Striped Bass angled from Minas Basin during 2008 (dark grey bars), 2009 (medium grey bars), and 2010 (light grey bars)...... 48

Figure 2-8. Age frequency of Striped Bass angled from Minas Basin during 2008 (light grey bars), 2009 (dark grey bars), and 2010 (medium grey bars)...... 48

Figure 2-9. Observed length (FL, cm) at age (yr) and the predicted von Bertalanffy growth curve of Striped Bass (N= 1022) angled from Minas Basin during 2008-2010...... 49

Figure 2-10. Sequential Bayes population estimates of Striped Bass based on mark-recapture data within the immediate area of Grand Pré, NS tagging site...... 50

Figure 3-1. Upper Bay of Fundy inset within a map of the Maritimes...... 89

Figure 3-2. Predicted flow speeds (m/s) and direction in the Minas Passage during a typical flood tide (top) and a typical ebb tide (bottom)...... 90

Figure 3-3. Orientation of mooring components...... 91

Figure 3-5. Code detection efficiency (cde) metric values (black dotted line) and tidal range (gray dashed line) throughout the study for receiver Stations 1-7 from top to bottom respectively. ... 93

Figure 3-7. Daily noise quotient (nq) metric values (black dotted line) and tidal range (gray dashed line) throughout the study for receiver Stations 1-7 from top to bottom respectively.. .. 95

Figure 3-8. Paired boxplots of daily performance metrics indicated by receiver station...... 96

Figure 3-9. Distribution of detected (top) and missed (bottom) transmissions binned by hour of day in which they were expected...... 97

Figure 3-10. Daily proportion of expected transmissions logged successfully by each receiver station...... 98

Figure 3-11. The estimated (solid line) effect of current velocity (m/s) on detection probability of V16 sentinel tags during ebb (black) and flood (red) tide at varying distance between sentinel tag and receiver...... 99

Figure 3-12. The estimated (solid line) effect of current velocity (m/s) on detection probability of V13 sentinel tags during ebb (black) and flood (red) tide at varying distance between sentinel tag and receiver...... 99

Figure 3-13. The estimated (solid line) effect of current velocity (m/s) on detection probability of V9 sentinel tags during ebb (black) and flood (red) tide at varying distance between sentinel tag and receiver...... 100

Figure 3-14. The estimated (solid line) effect of current velocity (m/s) on detection probability of V7 sentinel tags during ebb (black) and flood (red) tide at varying distance between sentinel tag and receiver...... 100

Figure 3-16. Example of the predicted probability (solid line) and 95% confidence intervals (dashed lines) produced by the most parsimonious model for October 17, 2009...... 102

Figure 4-1. Minas Basin and Minas Passage (MP) study area. Striped Bass tag release sites, are indicated by black diamond icons...... 142

Figure 4-2. Compact SUBS streamlined mooring package utilized during 2010 deployments.. .. 143

Figure 4-3. Overview of VEMCO VR2w acoustic receiver mooring positions within Minas Passage during 2010...... 144

Figure 4-4. Distribution of Striped Bass detections logged by receiver stations within the MPS array (top panel) and FORCE array (bottom panel) binned by hour of day in which they occurred...... 145

Figure 4-5. Boxplot showing daily Striped Bass detection counts, by tidal range (m), for all stations within Minas Passage...... 146

Figure 4-6. Total number of Striped Bass detections recorded during June-November, 2010 in relation tidal stage and depth-averaged current speed, binned by 0.25 m/s intervals...... 147

Figure 4-7. Total number of Striped Bass detections recorded during June-November, 2010 in relation to receiver array and depth-averaged current speed, binned by 0.25 m/s intervals. ... 147

Figure 4-8. Daily detections of acoustically tagged Striped Bass during June-November, 2010. 148

Figure 4-9. Spatial distribution of detections within Minas Passage during June-November, 2010 for individual Striped Bass released from the Stewiacke River tagging site...... 149

Figure 4-10. Spatial distribution of detections within Minas Passage during June-November, 2010 for individual Striped Bass released from the Grande Pré tagging site...... 150

Figure 4-12. Scatterplot indicating the association between detection depth (m, below surface) and depth-averages current speed (m/s) at time of detection for acoustically tagged Striped Bass detected within the FORCE test site during June-November 2010...... 152

Figure 4-13. Summary boxplots indicating depth (m, from surface) of all Striped Bass detections at each receiver station within the MPS array...... 153

Figure 4-14. Summary boxplots indicating depth (m, from surface) of all Striped Bass detections at each receiver station within the FORCE demonstration site array ...... 154

Figure 4-15. Kernel density plots of detection depth (m, below surface) of Striped Bass detected on the MPS array, as influenced by tidal stage (Ebb = pink shading, Flood = blue shading)...... 155

Figure 4-18. Kernel density plots of detection depth (m, below surface) of Striped Bass by time of day (Day = pink shading, Night = blue shading)...... 158

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ABSTRACT

The Bay of Fundy (BoF) Striped Bass population, currently assessed as

Endangered by COSEWIC, is generally not well understood. Despite increased overall research effort, the marine phase of the population has received limited investigation.

Two potential threats facing the population, an unmonitored recreational fishery and encounter risk associated with testing of tidal in-stream energy conversion (TISEC) devices, were investigated using creel survey, mark-recapture tagging, and acoustic telemetry techniques. Recreational catch was dominated by 3-4 year olds (comprising

75% of the catch). Limited capture of bass of retainable size (≥68cm TL) resulted in high rates of catch and release (>95%). Recaptures indicated a limited summer-fall movement range, with evidence of site residency and inter-annual site fidelity. VEMCO telemetry equipment experienced reductions in range and detection efficiency as current speed increased. Current speed, tidal stage, tag power, and distance were significant predictors of detection success. Of 80 acoustically tagged bass, 53 were detected within Minas Passage; 26 were detected only within Minas Basin. Larger bass

(>55 cm TL) released from the Stewiacke River site were present within Minas Passage and the FORCE site more regularly and at deeper depths (surface to >95m) than smaller bass (<55 cm TL) tagged at Grand Pré. Future research should focus on Striped Bass behaviour in the FORCE turbine test area, including their detection and evasion of TISEC devices.

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LIST OF ABBREVIATIONS AND SYMBOLS USED μ yearly exploitation A annual mortality AICc second-order Akaike information criterion AUL Acadia University Line Array BoF Bay of Fundy C number of fish captured within sampling interval cde code detection efficiency CI confidence interval cm centimeters CPUE catch per unit effort DFO Fisheries and Oceans Canada F fishing mortality FL fork length FORCE Fundy Ocean Research Centre for Energy GLM generalized linear model iBoF Inner Bay of Fundy

Ip proportional presence index

K growth rate, rate to reach L ∞ kg kilogram

L∞ maximum length

Lt length at time t m meter M number of fish marked at start of sampling interval MPS Minas Passage Line Array

Np number of days detected Nq noise quotient

Nt total number of days available for detection OTN Ocean Tracking Network R number of marked fish recaptured within sampling interval rc rejection coefficient S annual survival SD standard deviation SR Shubenacadie River sec second t0 theoretical age at which length is zero (0) TISEC tidal in-stream energy conversion TL total length VR2w VEMCO acoustic receiver Wt weight Z total instantaneous mortality

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ACKNOWLEDGEMENTS

By all accounts, this has been a lengthy process. However, the extended duration has provided many benefits including opportunities to develop professional relationships, collaborations, and unique opportunities to gain knowledge and experience. I have many people to thank that have participated, encouraged, and supported this project.

First, I thank my supervisor Anna Redden for her continued support, guidance, and understanding. Thank you for taking that initial chance on me, sticking with me, trusting me, and providing me with the many countless opportunities for both personal and professional development. Thank you for all the long hours, late nights, and weekends of editing. Your tireless efforts in support of the staff and students of ACER are appreciated greatly. With much gratitude I acknowledge the time, advice, and support provided by committee members Rod Bradford and Michael Stokesbury, who provided important thrusts toward initiating this research project, and valuable perspectives on this work throughout its development. Thank you both for providing me with additional opportunities to learn and gain experience. I thank Mike Dadswell and Mike Brylinsky for encouraging my interest in all things fish and fishing. I am grateful, always, for the help and thoughtful advice provided by my seemingly continual TA, Eddie Halfyard. Thank you for your willingness to answer my questions. You have been a great example for me to follow, no matter how much you try to downplay it. I hope we can finally go fishing now. Thank you also to Freya Keyser for being an invaluable support in figure preparation, R coding, reviewing, editing, and brainstorming.

Lab mates and friends: Colin Buhariwalla, Peter Porskamp, Errol Webber, and J.P. Hastey, provided considerable support toward this research particularly during the early stages. Thank you to Richard Karsten and Brian Sanderson for responding to numerous requests for modelled tidal parameters.

More technical aspects of this research were enhanced by the knowledge, experience, and learning opportunities provided by Duncan Bates, Stephane Kirchhoff, Murray

Scotney, Dan Wellwood, Richard Vallee, Dale Webber, and Matthew Holland. The Ocean Tracking Network (OTN) generously provided equipment, technical assistance, and data management throughout the duration of this project. Special thanks are extended to Fred Whoriskey, Susan Dufault, Margie Hall, and all other supporting members of the OTN staff for all they have done to support me and this project. The success of this research also rested heavily on the assistance and considerable experience of local fishers Mark Taylor, the late Croyden Wood Jr., and their respective crews.

The research was aided significantly by the support and interest of countless recreational anglers – too many to name, and many names which I may no longer remember. Thanks to all those who frequented “The Guzzle” allowing me to survey their catch and for reporting tag returns. Members of the Striped Bass Anglers Association of Nova Scotia (SBAANS), particularly Barry Locke, Owen Marr, and Derrick Nevin, were integral in collection of bass in the Stewiacke River for acoustic tagging. Thanks to Anthony (Tony) Lewis and Rusty Wilcox for providing intertidal weir access, hospitality, and perspectives on Striped Bass at their respective weirs.

I am extremely grateful for the directed funding and/or in-kind support provided by the Offshore Energy Research Association (OERA, formerly OEER), the Fundy Ocean Research Centre for Energy (FORCE), MITACS, VEMCO, the Ocean Tracking Network (OTN), Nova Scotia Power Inc. (NSPI), Fisheries and Oceans Canada (DFO), Acadia University, and the Acadia Centre for Estuarine Research.

To Dad, Mom, Derrek, Joan, and the rest of my family and friends, thank you for seeing me through this and for not giving up on me. You have all been tremendous supports in many different ways. Finally to Joanna - remember that patience is a virtue….you are obviously very virtuous! Thanks for being there through all of it. Your love, support, encouragement, prodding, and eventual frustration have helped me through. Love you!

A very big thank you to all those mentioned, and to any whom I may have forgotten.

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DEDICATION

For my two best girls – Jo and Maddie.

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CHAPTER 1 – General Introduction

The Striped Bass ( Morone saxtilis, Walbaum 1792) is an anadromous species that occupies near shore (<10km) marine habitat along the eastern seaboard of North

America (Setzler et al., 1980; Scott and Scott, 1988; Rulifson and Dadswell, 1995;

Collette and Klein-MacPhee, 2002). Native spawning stocks are associated with major river estuaries ranging from the St. Lawrence River, Quebec to the St. John’s River,

Florida (Scott and Scott, 1988, Figure 1-1). Throughout this range Striped Bass play an important ecological role as a high-order predator in estuarine and near-shore marine communities (Setzler et al., 1980; Collette and Klein-MacPhee, 2002) and support important recreational, commercial, and First Nations food, social and ceremonial (FSC) fisheries (Scott and Scott, 1988; Rulifson and Dadswell, 1995; Collette and Klein-

MacPhee, 2002).

Striped Bass utilize freshwater, estuarine, and near shore marine habitats in the completion of their life cycle, but exhibit varying degrees of anadromous migration over their range (Setzler et al., 1980; Secor, 1999; Wingate et al, 2011). The outcomes of mark-recapture tagging experiments have demonstrated several large scale patterns: 1)

Striped Bass stocks located north of Cape Hatteras, North Carolina undertake some degree of marine migration, 2) an Atlantic coastal migration of US populations north of

Cape Hatteras extends northward during summer, followed by a reverse migration in fall to southern overwintering areas, and 3) the majority of Atlantic coastal migrants (largely adult females) originate from stocks in the central portion of the range (namely

Chesapeake Bay, and the Delaware and Hudson Rivers) (Merriman, 1941; Raney, 1957;

Chapoton and Sykes, 1961; Nichols and Miller, 1967; Clark, 1968; Kohlenstein, 1981;

Boreman and Lewis, 1987; Waldman et al., 1990). Interestingly, Striped Bass stocks from both the southern and northern extremes of the range have been identified as either non-anadromous or are thought to exhibit migratory movements of reduced extent

(Raney, 1957; Setzler et al., 1980; Hassler et al., 1981; Douglas et al., 2003).

In Canadian waters, three Striped Bass populations (or Designatable Units, DU’s) have been identified and occur in the St. Lawrence River, the Gulf of St. Lawrence, and the Bay of Fundy (Douglas et al., 2003; Bradford et al., 2012; COSEWIC, 2012). These populations have been attracting increased attention due to recent decisions made in relation to their conservation status (Bradford et al., 2012; COSEWIC, 2012; DFO, 2014).

In 2012, all three identified populations were re-assessed by the Committee on the

Status of Endangered Wildlife in Canada (COSEWIC) (COSEWIC, 2012). The St. Lawrence

River population assessment was downgraded from Extirpated (COSEWIC, 2004) to

Endangered following successful re-introduction of Striped Bass to historic areas

(COSEWIC, 2012). The Gulf of St. Lawrence population assessment was also downgraded from Threatened (COSEWIC, 2004) to Species of Concern (COSEWIC, 2012). The Bay of

Fundy (BoF) was the only population to receive an upgraded assessment to Endangered

(COSEWIC, 2012; DFO, 2014), from its prior assessment as Threatened in 2004

(COSEWIC, 2004).

The Bay of Fundy Striped Bass population historically consisted of three spawning stocks located in the Saint John River, NB, and Annapolis and Shubenacadie

Rivers, NS. Justification for the BoF population being upgraded to endangered status

2 was: “This large-bodied fish occurs at only a single known spawning location where it continues to be susceptible to exploitation from recreational fishing, by-catch in commercial fisheries, and from poaching. Habitat degradation continues in areas of historical spawning populations, which limits recovery potential” (COSEWIC, 2012). As only the Shubenacadie River (SR) spawning stock is known with certainty to be reproductively active, the entire BoF population could be susceptible to extirpation should the SR stock suffer any substantial environmental or anthropogenic impact

(Bradford et al., 2012; COSEWIC, 2012).

Shubenacadie River Striped Bass are genetically distinct from all other Striped

Bass populations in eastern North America (Wirgin et al., 1993; Bradford et al., 2012) and are one of the few stocks in which some proportion of individuals overwinter in freshwater (Rulifson and Dadswell, 1995; Bradford et al., 2012). Shubenacadie River

Striped Bass are also the only stock known to spawn successfully in a tidal bore dominated river (Rulifson and Tull, 1999). The body of biological data specific to the BoF

Striped Bass population has increased considerably over the last two decades (Rulifson and Dadswell, 1995; Rulifson and Tull, 1999; Paramore and Rulifson, 2001; Douglas et al., 2003; Cook et al., 2006; Rulifson et al., 2008; Cook et al., 2010; Bradford et al., 2012;

MacInnis, 2012). However, the adult marine and migratory phase of the species life cycle remains poorly understood. Past conventional tagging studies of Striped Bass originating from the SR have indicated that their migrations may be largely contained within Minas Basin (Douglas et al., 2003; Bradford and Leblanc, 2011; Bradford et al.,

2012), and while the SR stock abundance is thought to be stable, time-series data on

3 population abundance is limited which presents challenges to confirming or refuting this belief (COSEWIC, 2012).

Protection and management of anadromous species in the Maritime Region, including Striped Bass, are the responsibility of the Department of Fisheries and Oceans

Canada (DFO). Striped Bass management by DFO has not been guided to any great extent by empirical science, but rather by pragmatic application of increasingly restrictive fishery regulations (Bradford et al., 2012). Beginning in 1978, regulatory changes (summarized by Bradford et al. (2012); see Appendix 1-A) have resulted in: 1) closure of all directed commercial fisheries; 2) bag limits and retention size restrictions in the recreational fishery; and 3) reduced by-catch allotments within other commercial fisheries toward limiting overall retention (COSEWIC, 2004; Bradford et al., 2012;

COSEWIC, 2012).

Striped Bass management in the Maritime Region is precautionary (DFO, 2006b;

Bradford et al., 2012). Within this framework, and in light of present uncertainty surrounding population abundance, conservation-focused management actions are applied to preemptively manage risks of potential threats (Stephenson, 1999; Hilborn et al., 2001; DFO, 2006a; Cadrin and Pastoors, 2008; Gregory and Long, 2009). At this time, insufficient information is available to determine population abundance for the SR

Striped Bass stock. This prevents the determination of population conservation reference points to guide allocations of harvest allotments for ongoing First Nations food, social and ceremonial fisheries (FSC), by-catch allowances in fisheries targeting other species, and the recreational fishery (Bradford et al., 2012).

Lack of long term population abundance data, in combination with a poor understanding of BoF Striped Bass, specifically the SR stock, leads to uncertainty regarding the sustainability and potential susceptibility of the population to negative impacts. Knowledge gaps include: a limited understanding of marine habitat use and extent of migration, the possibility of mixing with seasonal migrants of populations originating outside of the Bay of Fundy, and limited information regarding exploitation within recreational and commercial by-catch fisheries (COSEWIC, 2012). Without a clear understanding of population abundance and its inherent natural variability, determining the effectiveness of future monitoring and management actions toward protection and conservation of the population may prove difficult (Piet et al. 2010). Bay of Fundy

Striped Bass face several population level threats for which the potential level of risk has not been quantified (COSEWIC, 2012). Most notable are: the continued expansion of the unlicensed and therefore unmonitored recreational fishery (Bradford et al., 2012;

COSEWIC, 2012), and interaction with planned installations of tidal in-stream energy conversion (TISEC) devices at the Fundy Ocean Research Center for Energy (FORCE) within Minas Passage, NS (FORCE, 2011; DFO, 2012).

1.1 THESIS OBJECTIVES

To address knowledge gaps regarding Bay of Fundy Striped Bass movement patterns, habitat use, population dynamics, and angling pressure in Minas Basin, this thesis study seeks to:

1) Characterize the Striped Bass recreational fishery and effort at a popular angling site

located within Minas Basin – Grand Pré, NS;

2) Describe the near-shore presence of Striped Bass within Minas Basin during spring

through fall using mark-recapture techniques;

3) Determine size, age, and mortality for Striped Bass captured in the Minas Basin

recreational fishery;

4) Examine the efficacy of using VEMCO acoustic telemetry technology in and near the

FORCE test site. This involves range testing and assessment of tag detection efficiency

as a function of transmitter power output, tidal stage and current speed; and

5) Quantify Striped Bass spatial use of the Minas Passage and the FORCE TISEC test site,

during summer through fall, using VEMCO acoustic telemetry.

1.2 THESIS ORGANIZATION

This thesis contains three data chapters, and a concluding general discussion chapter. The data chapters have been written as stand-alone sections with supporting tables and figures. Effort was made to limit repetition in site descriptions, methods, and

6 figures. Where necessary, figures and/or tables have been referenced from previous chapters. A cumulative reference list is located at the end of the thesis.

Chapter 2 - Characteristics of Striped Bass angled in the Minas Basin, NS recreational fishery. This chapter provides the first multi-season, creel-census examination of the Minas Basin Striped Bass recreational fishery at a popular angling site (Grand Pré, NS), and also examines the near shore presence and movement patterns of Striped Bass using traditional mark-recapture tagging methods.

Chapter 3 - Detection range and efficiency of VEMCO acoustic telemetry technology under extreme hyper-tidal conditions in Minas Passage, Bay of Fundy. In this chapter, passive acoustic telemetry equipment is evaluated to determine the detection range and efficiency of VEMCO VR2w receivers with various transmitter powers (tags

V7-V16, output power 143-165dB) under natural tidal flow conditions within Minas

Passage.

Chapter 4 - Detection of acoustically tagged Striped Bass across Minas Passage and within the FORCE test area . This chapter applies findings from the range test results

(Chapter 3), and uses passive acoustic telemetry to investigate temporal and spatial patterns in movement of acoustically tagged Striped Bass in Minas Passage and the

FORCE TISEC test area.

Chapter 5 – General Discussion . This chapter synthesizes the study’s main findings with a discussion of limitations, challenges, and implications. Recommendations for future research are presented.

1.3 FIGURES

St. Lawrence River, QC

Cape Hatteras, NC

St. John’s River, FL

Figure 1-1. Native distribution of Striped Bass ( Morone saxatilis ) along the Atlantic coast of North America. (Figure modified from www.aquamaps.org).

1.4 APPENDIX Appendix 1-A. Chronology of consultative and legislative management actions, relative to Bay of Fundy Striped Bass, implemented since 1978 (from Bradford et al., 2012).

Year Management Action 1978 • Commercial: Licensed fishery ceased, no targeted harvest permitted. 1994 • Recreational: Reduced bag limit from 5 to 1 fish per day. • Recreational: Retention Size Limit Increased: ≥48cm TL. 1995 • Recreational: Retention Size Limit Increased: ≥58cm TL. 1996 • Bycatch: Federal regulations amended to prevent retention and sale of incidentally captured Striped Bass in any other licensed fishery. • Recreational: Retention Size Limit Increased: ≥68cm TL. 1997 • Bycatch: Minas Basin weir fishers permitted retention of one fish ≥68cm TL per day. • Bycatch: Shubenacadie drift net fishers permitted to retain: 3 fish (>3.6kg) per day. • Bycatch: Shubenacadie River Gaspereau dip net fishers to release all Striped Bass. • Bycatch: Saint John River drift net and trap fishers permitted to retain one fish ≥68cm TL. • Bycatch: Stewiacke River upstream of Stewiacke Landing closed to drift netting, and shad season shortened by 2 weeks (May 31 st closure). 2003 • Bycatch: Shubenacadie River Gaspereau fishery not permitted at night during peak Striped Bass migration from Grand Lake. 2008 • Aboriginal: Agreement reached on retention restrictions for subsistence and ceremonial harvest. • Recreational: Hook and release only of Striped Bass from about mid-May to mid-June for the following waters: the inland and tidal waters of Grand Lake and the Shubenacadie River downstream to its confluence with the Stewiacke River, and the inland and tidal waters of the Stewiacke River downstream from the highway bridge (Pollock Bridge) in Stewiacke East to its confluence with the Shubenacadie River. • Recreational: Artificial fly and single hook, or un-baited lures only, regardless of the species being fished, from about mid-May to mid-June for: tidal waters of the Shubenacadie River downstream from the CN Railway Bridge at East Milford to its confluence with the Stewiacke River, and the inland and tidal waters of the Stewiacke River downstream from the highway bridge (Pollock Bridge) in Stewiacke East to its confluence with the Minas Basin. • Bycatch: Weir fishers limited to a maximum seasonal catch of between 10 and 40 Striped Bass ≥68 cm TL. The allocation is based on site and personal use requirements and is intended to cap retention across a 3-4 month season. 2009 • Bycatch: Shubenacadie shad drift net fishers reduced from 3 Striped Bass < 8 lbs (3.6 kg) per day to 1 Striped Bass per day, 68 cm or more in total length. • The transition with time to a common retention limit of one Striped Bass > 68 cm in total length per day, in all fisheries, and seasons where retention is authorized, is intended to allow for Striped Bass surviving to maturity to have the chance to spawn at least once before their potential removal from the population.

CHAPTER 2 - Characteristics of Striped Bass ( Morone saxatilis ) angled in the Minas Basin, NS recreational fishery

2.1 INTRODUCTION

The BoF has a long history of recreational angling targeting Striped Bass (Jessop and Doubleday, 1976; Jessop and Vithayasai, 1979; Jessop, 1980; Rulifson et al., 1987;

Harris and Rulifson, 1988; Peterson, 1991; Rulifson and Dadswell, 1995). Until recently, recreational angling within Minas Basin was generally low effort and low yield, which reflected low abundance of harvestable sized bass (Rulifson et al., 1987; Rulifson and

Dadswell, 1995). Since the mid 1990’s, a resurgence in the abundance of Striped Bass has occurred concurrently with declines in other recreationally important species (i.e.

Atlantic Salmon (Salmo salar ), Brook Trout (Salvelinus fontinalis )) (Rulifson and

Dadswell, 1995; Bradford et al., 2012). Regulatory changes to conserve the BoF population by limiting overall exploitation and retention (summarized in Bradford et al.,

2012; Appendix 1-A), combined with a recent instance of high episodic recruitment have resulted in a strong pulse of large bodied bass of retainable size (≥68 cm TL), in turn prompting increased interest in the recreational fishery (Bradford et al., 2012). Statistics from the Survey of Recreational Fishing in Canada (SRFC), which is compiled from the voluntary responses of anglers, indicated that the number of Striped Bass anglers has increased from 4299 to 7248 anglers between the years 2000 and 2010 (Table 2-1; DFO,

2003; 2007; 2012).

The recreational Striped Bass fishery within Minas Basin constitutes an established fishery of considerable economic value, rivaling the number of participant

10 anglers in the NS Atlantic Salmon fishery at its peak (R. Bradford, DFO, pers. comm.).

Recreational angling of Striped Bass in tidal waters is open access and not licensed.

Given the widespread distribution of recreational angling activity throughout Minas

Basin, and lack of a licensing structure, it is difficult to gather angler participation or exploitation information. Further, the capacity of Fisheries and Oceans Canada (DFO) to monitor and provide enforcement presence has decreased in recent years. Despite the perceived upward trend in angler abundance indicated by the SRFC, there is currently no reliable means to quantify the number of participating recreational anglers or to estimate with confidence overall exploitation/retention.

While the Minas Basin has become a focus of recreational angling activity within the BoF (Bradford et al., 2012), limited information is available regarding the summer- fall fishery within Minas Basin tidal waters. In general, historical angling data for the BoF is limited, and focuses primarily on angling within the once locally important recreational fishery of the Annapolis River, NS (Jessop and Doubleday, 1976; Jessop,

1980; Harris and Rulifson, 1988), or the SR spawning area (Jessop and Vithayasai, 1979).

A single season creel survey of the Grand Pré area within Minas Basin was conducted by

Rawley (2008) but was limited in both effort and duration. As recreational angling within the Minas Basin occurs primarily during periods outside of spring spawning activity for the SR stock, it is generally assumed that it exploits a combination of both Canadian and

US origin bass (Rulifson and Dadswell, 1995; Bradford et al., 2012). Past conventional mark-recapture tagging studies (Rulifson et al., 2008; Bradford et al., 2012) indicated that Minas Basin Striped Bass fisheries disproportionately exploited local bass with

11 contingents of non-local migrant bass present in varying abundance inter-annually.

Despite their variable abundance, it is suspected that the presence of migrants enhances the catch rate of recreational anglers, and may convolute perceptions of local stock abundance (Douglas et al., 2003). Acknowledging that the Minas Basin recreational Striped Bass fishery constitutes a mixed-stock aggregation introduces a level of uncertainty in describing the biological characteristics of the exploited population and in assessing anthropogenic impacts, including from the recreational fishery, on the local SR stock.

Managers have often struggled with how best to assess fisheries consisting of multiple stocks which overlap in habitat range, particularly if one of the stocks is in a depressed state relative to the others (Waldman et al., 1988, Ruzzante et al., 1999;

Stephenson, 1999; Gregory et al., 2013). Effective fisheries management requires population level data regarding abundance, size and age structure, as well as population growth, survival and mortality rates (Pine et al., 2003). Collection of population data can be difficult for migratory species (Cadrin and Secor, 2009), and sampling of populations is deliberately limited for species identified as at risk (Runge, 2011). In addition, further complexities in assessing the status of the BoF Striped Bass population include: the variable and overlapping presence of migrant bass of US stock origin (Wirgin et al., 1993;

1995; Rulifson and Dadswell, 1995; Douglas et al., 2003; COSEWIC, 2012), a local stock structure which is not well defined (Bradford et al., 2012), and lack of knowledge regarding the extent of migration of the SR stock (Bradford et al., 2012). Given current knowledge gaps regarding Striped Bass population abundance, habitat use, movement

12 patterns, and migratory extent within the BoF system, development of pre- and post- impact assessments of anthropogenic activities, including the recreational fishery, on the BoF Striped Bass population will be challenging to complete in a timely and robust way.

This study is the first multi-year research program to describe the intertidal recreational Striped Bass fishery in the Minas Basin, NS. To better understand impacts of the recreational fishery on the population, it is important to monitor angling effort outside of the SR spawning season. While challenges exist in relating recreational angling activity within the Minas Basin to potential impacts on the local SR stock, collection of such information will inform and help validate other metrics currently being used to assess the local stock (Bradford et al., 2012; COSEWIC, 2012; McInnis,

2012).

For this project, a combination of creel survey and mark-recapture methods were used to assess population characteristics of Striped Bass angled from the summer feeding aggregation (Rulifson et al., 2008) within Minas Basin. Objectives of this multi- year study at a popular angling site (Grand Pré, NS) address the following knowledge gaps:

1) near-shore presence and site fidelity of Striped Bass during spring through fall,

2) Striped Bass angling effort (CPUE, exploitation/retention, catch and release), and

3) Length and age of the catch, and indices of mortality.

2.2 MATERIALS AND METHODS

2.2.1 Study Site Description

The BoF is a highly dynamic marine environment situated at the head of the Gulf of Maine between the US state of Maine, and the Canadian provinces of New Brunswick and Nova Scotia (Figure 2-1). At the head of the BoF, the Chignecto Isthmus divides the region into two separate water bodies, Chignecto Bay to the north and the Minas Basin to the south, which together comprise the inner Bay of Fundy (iBoF). The southern portion of the iBoF, contained entirely within the province of Nova Scotia, is approximately 100km long and 30km wide at its widest point, and consists of four primary areas: Minas Channel, Minas Passage, Minas Basin, and Cobequid Bay, situated from West to East, respectively (Figure 2-2).

The iBoF is an extreme hyper-tidal system (Archer, 2013), dominated by near resonant semi-diurnal tides with a periodicity of 12.42hrs (Greenberg 1984, Karsten et al., 2008). The area is characterized by an extreme tidal range (up to 16m) (Parker et al.,

2007), strong tidal currents (in excess of 5m/s) within Minas Passage (Karsten et al.,

2008), turbulent flow (Greenberg 1984), and high suspended sediment loads within the

Minas Basin (Amos and Alfoldi 1979). Tidal flushing and turbulence creates strong mixing of the water column, which limits temperature and salinity stratification, and causes re-suspension of sediments from tidal flats (Parker et al. 2007).

During low tide in Minas Basin vast areas of intertidal mudflats are exposed.

These flats can extend up to several kilometers in width, with up to 2/3 of the total

14 seafloor in Cobequid Bay being exposed during low tide periods (Parker et al., 2007).

Water temperatures in near-shore intertidal areas may exceed 22°C in summer and become super-cooled (-1.5°C) during winter (Parker et al., 2007). Salinity within Minas

Basin is variable (24-31 ppt) depending upon season and levels of freshwater input

(Bousfield and Liem, 1959; Parker et al., 2007).

Striped Bass are common to the Minas Basin and are the target of a large recreational angling fishery (Bradford et al., 2012; DFO, 2014). Striped Bass were sampled from the near shore angling location of Grand Pré, NS, known locally as “The

Guzzle” (Figure 2-2). This sampling location was selected due to its popularity with the recreational angling community and proximity to Wolfville, NS (Figure 2-2) and Acadia

University.

2.2.2 Field Methods - Angling

Striped Bass were surveyed through angling (rod and reel) during May - October

2008, May - September 2009, and May - August 2010. Angling survey periods were conducted around high tide during daytime, with one tide per day generally surveyed.

These time periods included the last 2 hours of the flood tide and first 2 hours of ebb tide. Survey periods corresponded with the timing favored by recreational anglers.

During each survey, counts were made of the number of anglers present and the number of rods in use by each angler. Arrival and departure times of anglers were noted to provide detailed catch and effort information. The survey team members also participated in the angling of Striped Bass and were included in the total angling effort.

Tackle of most fishers consisted of heavy 8-12 ft surf style rods and large capacity reels spooled with ≥20lb test line. Terminal tackle consisted predominantly of hi-low style dropper rigs, used in conjunction with various hook styles but generally ranging between sizes 4/0-8/0, weighted with 3-6oz lead sinkers. Principal baits were chunked or filleted Atlantic Mackerel ( Scomber scombrus ) and Atlantic Herring ( Clupea harengus ). Other baits such as American Shad ( Alosa sapidissima ), Alewife/Gaspereau

(Alosa pseudoharengus ), and Longfin Squid ( Loligo pealei ) were used periodically when in season.

2.2.3 Striped Bass Sampling

Upon capture, each Striped Bass was assessed for general health and suitability for tagging. Bass were rejected if there was excessive fight time (generally >3mins), deep hooking (stomach, gill, eye, etc.) and associated bleeding, or difficult hook removal

(greater than 1 min duration) which increased air exposure time. Bass hooked in the mouth, landed quickly, and with little to no loss of blood were measured and tagged, while those deemed unfit were returned to the water as quickly as possible, revived (by directing water over the gills), and released.

Striped Bass selected for tagging were placed left side up on a wet fish measuring board and measured to the nearest 0.1cm. Typically, both fork and total lengths were recorded. A blunt knife was used to collect 4-6 scales from an area above the lateral line and slightly anterior of the first dorsal fin and stored in paper envelopes.

Next, a small fin clip was taken from the left pelvic fin and placed in a numbered vial

16 containing 95% ethanol solution. A 7.5cm FT-1 T-Bar style tag (FLOY, Seattle, USA) was inserted on the left side between the 2 nd and 3 rd dorsal spines of the anterior dorsal fin.

Each Floy tag contained a unique identifier number and included return address information (Acadia Biology, Wolfville, NS, B4P 2R6).

For each Striped Bass tagged, sampling location, time, date, hook type, and tag number were recorded. During 2008, Striped Bass were also weighed to the nearest

0.1kg using a sling and spring scale. Weight measurements were discontinued after

2008 as they considerably increased the time of air exposure. After completion of all sampling procedures each bass was returned to the water, revived if necessary by forcing water across the gills, and then released.

Also tagged were small numbers of Striped Bass captured during spring and summer in Minas Basin intertidal fishing weirs located near Five Islands and Walton

(Figure 2-2). As they were not angled, Striped Bass tagged within weirs were only considered in the analysis of recapture and movement patterns and not included in analyses related to the characterization of the recreational fishery.

In all years, the sampling methods were reviewed and approved by the Canadian

Council for Animal Care through Acadia University’s Animal Care Committee (Permit 06-

10), and DFO under Section 52 and 56 of the General Regulations - Federal Fisheries Act

(Scientific License # 322857).

2.2.4 Notices to Anglers

To inform anglers of this study, and to promote tag returns, posters were placed at common fishing locations as well as other areas that anglers frequent (post offices, gas stations, convenience stores, tackle shops, etc.). These posters described the tagging program, indicated the anatomical positioning of tags, provided a description of the tag, and gave contact information for the reporting of recaptured fish (Appendix 2-A).

Similar information was also posted on the recreational fishing website: www.NovaScotiaFishing.com. No monetary reward was offered for the return of tag information.

2.2.5 Analysis of Samples and Data

Three scales were selected from each sampled Striped Bass for age determination. Regenerated scales were common and care was taken to exclude regenerated scales (re-grown following scale loss) from aging analysis. Selected scales were cleaned with a 70% ethanol solution, and immediately mounted between two glass microscope slides to prevent warping. A dissection microscope (Leica Wild M3B,

16x) was used to view annular growth rings, which were counted to determine age of fish sampled. Successive alternating wide circuli (clear, summer growth) and tightly spaced annuli (dark, winter periods) were counted outward from the scale focus

(Murphy and Willis, 1996). Each mount of three scales was read by two individuals for validation purposes. Age determination from annuli counts of multiple scales, and results between readers were compared for consistency; in cases where disagreement occurred, the scale was read a second time by the principle reader.

Angling effort (or the number of rod hours) was recorded by tracking both the number of anglers and the number of rods used per angler during each tide sampled.

Yearly catch per unit effort (CPUE) was determined by relating the total catch to the effort exerted within a given year (Murphy and Willis, 1996). Similarly, the yearly CPUE of retainable size fish (≥ 68cm TL) was determined by relating the number of retainable size fish caught to the angling effort. Yearly exploitation (μ) was calculated by relating the number of recaptured individuals (r) to those marked (m) with tags, for each sampling year (Ricker, 1975).

Total instantaneous mortality (Z) estimates were derived from slopes of linear regressions relating the natural log of abundance to year class (Ricker, 1975). Age classes not yet fully recruited to the fishery (2 years of age and younger), and those age classes which contained less than 5 individuals were excluded from the determination of slope. Annual survival rates ( S) were determined from the negative exponential of the total instantaneous mortality ( Z), and annual mortality ( A) was determined as the complement of the annual survival rate ( A = 1 – S).

All statistical tests were conducted using the statistical language and software environment R (R Core Development Team, 2014), and were considered significant at α

= 0.05. A von Bertalanffy growth curve was fit to observed length-at-age data using R

-k(t-t0) package “FSA”. The von Bertalanffy growth equation is as follows: L t =L ∞ *(1-e ) , where L t is the length at time t, L ∞ is the average maximum length, K is the rate to reach

L∞, and t 0 is the theoretical age at which length is zero (Ricker 1975).

Fork length and date information were used to calculate the growth increment

(change in length between time of release and time of recapture, mm), and time-at- large (time difference between date of release and date of recapture, days) for an estimate of daily growth (mm/day). Lengths reported by anglers were not used in growth calculations as measurement accuracy could not be verified. Striped Bass at large ≥10 days post marking were included in calculations. For individual bass that were captured multiple times, growth rates were determined using the longest period of time-at-large between captures.

Mark-recapture records were examined for movement patterns of individual

Striped Bass relative to the seasonal timing, location, and source of the recapture record. Multiple recapture records were examined for patterns of within-year and/or inter-annual site use.

To determine if Striped Bass from the Grand Pré tagging site exhibited traits of a closed (localized) population, mark-recapture population estimates were calculated for each survey year. Estimates were derived with a sequential Bayes algorithm, based on a binomial distribution representing sampling with replacement, as described by Gazey and Staley (1986). The following input parameters were used: the number of Striped

Bass captured within the sampling interval (C), the number of fish marked at the start of the sampling interval (M), and the number of Striped Bass collected that had been tagged in a previous sampling interval (recaptures, R) (Gazey and Stanley, 1986).

Sequential intervals were composed of 7-day sampling periods. To ensure that reporting

20 rate for recaptures was 100%, only data from Striped Bass originally tagged at the Grand

Pré site, and those bass recaptured during subsequent sampling events at the Grand Pré site were used in this analysis. Total numbers of marked fish available in each sampling interval were also corrected to account for removals (i.e. retention, death, or tag removal) observed during sampling events or reported by fishers. Tag loss was assumed to be negligible. Starting and step increment values were selected to ensure the tails of estimates approached a probability of zero. Estimates were examined to confirm the assumption of a closed population, where a continuous trend toward larger or smaller population size provides strong evidence that the population is not closed, but instead is either increasing or decreasing over the study period (Gazey and Staley 1986).

A Welch’s T-test was used to compare Striped Bass growth rates recorded within a single sampling year with those captured in subsequent years. Between year differences in number of anglers per tide, catch per unit effort (CPUE), and fork length

(FL) were examined using non-parametric Kruskal-Wallis one-way analysis of variance tests. Where significant (p < 0.05), a post-hoc Kruskal-Wallis multiple comparison test was performed.

2.3 RESULTS

2.3.1 Angling Effort and Catch Patterns

During 2008-2010 a total of 1066 angled Striped Bass were surveyed from Minas

Basin near Grand Pré, NS. They were captured from a total of 3198 rod hours. Effort

(rod hours) per tide was variable, and influenced by the number of anglers present and

21 the number of rods fished by each angler. No significant difference was found in the number of anglers present per tide among survey years (Kruskal-Wallis: H = 0.218, p =

0.89), where mean number of anglers per tide fished was found to be 6.3, 6.3, and 5.1 during 2008, 2009, and 2010, respectively (Table 2-2). Observed peaks in angler presence occurred during weekends and when high tides corresponded with late afternoon or early evening. Weekend periods throughout summer (July-August) attracted as many as 40 anglers during a single tide; monitoring the catch of all anglers present during peak angling periods was not possible.

Numbers of angled Striped Bass were greatest in Year 1 (51%) of the study.

Angled recaptures were similar across all years (range = 67 - 77) (Table 2-2). The number of legally retainable bass (≥68cm TL) was limited and decreased over the three study years (Table 2-2). CPUE was significantly different between years (Kruskal-Wallis: H =

16.92, p < 0.001), and the post-hoc multiple comparison test indicated that mean CPUE in 2010 (0.54) was significantly greater than in both 2008 (0.31) and 2009 (0.27). CPUE of retainable size fish (≥68cm TL) in 2008 and 2009 was found to be the same but decreased in 2010 (Table 2-2). Within years, CPUE was generally observed to increase monthly, with higher values of CPUE generally observed in September (Figure 2-3). Daily

CPUE data from all three study years were pooled to examine the influence of tidal range (Figure 2-4). Peaks in CPUE values appeared during periods of both neap and intermediate tidal range. Limited sampling during periods of greatest tidal range (≥13m) prevented inclusion in further analysis. A weak but significant negative correlation was found between tidal range and CPUE (Pearson’s: r = -0.189, p = 0.018). CPUE, by hour

22 of the day in which the high tide occurred, showed no clear pattern during the hours of

0500 – 2200 (Figure 2-5).

Four primary hook styles were used in capturing fish during 2009 and 2010: circle, standard (J), wide gap worm, and treble (Figure 2-6). During 2009, hook type usage was as follows: wide gap worm (40%), standard J (31%), circle hooks (27%), and treble (2%). In 2010, 68% of all fish were captured using circle hooks. (Figure 2-6).

2.3.2 Population Characteristics

Fork length (FL, cm) measurements were recorded in each year of sampling.

Weight (Wt, kg) measurements were recorded in 2008 only. A proportional length frequency distribution was used to compare lengths between years (Figure 2-7). Mean

FL decreased significantly over the study years (Table 2-2) (Kruskal-Wallis: H = 35.81, p <

0.001). A post-hoc multiple comparison test indicated that mean FL in 2010 (35.7 cm) was significantly smaller than in both 2008 (40.4 cm) and 2009 (38.4 cm).

A length-weight relationship, log(Wt) = 3.25log(FL) - 5.38, (r² = 0.93), was determined for measurements recorded during 2008. Slope of the weight-length regression indicated an overall condition factor (K) of 3.25.

Age determination indicated that Striped Bass catch within Minas Basin was dominated by the 3 and 4 year age classes, comprising >60% all fish captured in each survey year (Figure 2-8). Mean age differed significantly among years (Kruskal-Wallis: H

= 35.81, p < 0.001). A post-hoc multiple comparison test indicated that the observed difference was between survey years 2008 (4.2 yrs) and 2010 (3.8 yrs).

Within each year class, lengths of individual bass varied by as much as 20cm. The

–0.13(t-(-1.07) Von Bertalanffy growth equation L t = 85.44 (1 - e ) was determined using non- linear regression of fork length at age (Figure 2-9). Average maximum length (L ∞), the rate to reach L ∞ (K), and the theoretical age at which length is zero (t 0), were found to be

85.44cm, 0.13, and -1.07yr, respectively.

Growth rates calculated for all Striped Bass re-captured during multi-year sampling showed a mean growth rate of 0.39 (SD = ±0.31) mm/day (N = 148). Bass recaptured within the same season in which they were tagged exhibited an average growth rate of 0.63 (SD = ±0.2) mm/day (N=74, mean size at recapture = 35.4 (SD = ±4.9) cm FL). Mean growth rate of bass recaptured after at least one winter at large was 0.17

(SD = ±0.01) mm/day (N=74, mean size at recapture was 34.5 (SD = ±5.2) cm FL).

Total instantaneous mortality estimates (Z) were found to increase over the duration of the study (Table 2-2). Corresponding annual survival rate (S) decreased by study year, and therefore complementary values of annual mortality rate (A) also increased (Table 2-2).

2.3.3 Recaptures and Movement

A total of 1126 Striped Bass were tagged during this study. As of December 31,

2010, a total of 377 recaptures were reported, from 253 unique Striped Bass; overall recapture rate of 22.4%. Within year recapture rate decreased by study year (Table 2-4).

Recaptures were reported by three sources: 1) recreational fishery, 2) by-catch in commercial intertidal weirs, and 3) survey team members during sampling periods

(Table 2-5). Recapture records indicated that individual Striped Bass were captured and released on as many as six occasions throughout the study (Table 2-6).

Recaptured fish were at large an average of 194 days (SD = ± 211, N= 377, range=

1-754) post-tagging. Average fork lengths of recaptured fish were 36.3 (±4.7) cm, 39.5

(±5.3) cm, and 39.4 (±6.3) cm, in 2008, 2009, and 2010 respectively. Fork lengths at recapture were significantly different between study years (Kruskal-Wallis: H = 11.97, p

< 0.01). A post-hoc multiple comparison test indicated that the mean FL of striped bass tagged in 2008 (36.3cm) was significantly less than in both 2009 (39.5cm) and 2010

(39.4cm).

In all, 309 of 377 (81.9%) recaptures were reported from the site of initial tagging at Grand Pré, NS. These recaptures indicated that individuals returned, and/or were resident at the primary sampling site both within and among survey years. Individual recapture histories over multiple seasons indicated a greater diversity of locations visited, but these fish were generally found within Minas Basin (Table 2-7).

As of December 31, 2010, three tags had been reported seaward of the Minas

Basin: 1 from Bear River, Annapolis County, NS (170km, 379 days post-tagging), and 2 from Scots Bay, Kings County, NS (43km, 65 and 68 days post-tagging). No long-range returns were reported from the United States or locations beyond the Bay of Fundy.

Survey efforts did not detect any tags from other studies that would suggest movements of migrant bass to the Minas Basin.

2.3.4 Population Estimates

Median population size estimated by the terminal sequence within the three study years ranged from 1500-2520 Striped Bass within the localized area of the Grand

Pré tagging site (Table 2-8). Sequential estimates were observed to be variable over the early portion of each sampling year, but became more consistent with higher levels of confidence toward the end of each sampling year following multiple sequential estimates (Figure 2-10).

2.4 DISCUSSION

2.4.1 Angling Effort and Catch Patterns

This study presents the first multi-year assessment of recreational Striped Bass angling activity at the primary angling location of Grand Pré, within Minas Basin, NS. The

Grand Pré site was selected due to its popularity with the local recreational angling community, as well as its proximity to Acadia University, Wolfville, NS.

Angler abundance, on a per tide basis varied within years but did not vary greatly among survey years. As observed by Jessop and Vithayasai (1979) and Rawley (2008), peaks in angler presence occurred during weekend periods or when high tide happened in the late afternoon or evening, permitting anglers to fish following the end of the workday. While it is generally thought that recreational angling activity targeting Striped

Bass has increased (Rulifson and Dadswell, 1995; Rulifson et al., 2008; Bradford et al.,

2012), our study did not quantify the number of unique anglers encountered during each season. Results from the Survey of Recreational Fishing in Canada (SRFC) indicated that the number of anglers targeting Striped Bass within Nova Scotia increased from

2005 to 2010 (DFO, 2007; 2012). SRFC results, however, are based on information solicited from anglers who purchase a provincial recreational fishing license within the survey year. As no permit or license is currently required to recreationally angle for

Striped Bass in tidal waters of Nova Scotia, it is likely that SRFC results underestimated the number of anglers targeting Striped Bass.

Examination of angler success indicated that peak CPUE occurred during late summer and fall, similar to the timeframe of greatest weir catches (Rulifson et al.,

2008). When related to the tidal amplitude, the largest angler catches were associated with neap tide periods, standing in contrast to results of Rulifson et al. (2008), who reported peak captures in Minas Basin weirs at low water during spring tides. These conflicting results may reflect differing fish capture methodologies. Weir catches can be influenced by the interactions between tidal and diel cycles. In the present study angling was largely selective for Striped Bass aged 3 years and older, while the intertidal weirs are less selective, and are known to collect large schools of 1+ and 2+ bass. Due to limited beach access, angling surveys could not be conducted during peak spring tides

(>13 m). In contrast, intertidal weirs were occasionally made inaccessible during neap tides when waters do not fully recede.

Angler equipment was generally consistent within survey years; however, the proportional use of circle hooks increased between survey years 2009 and 2010. Circle hooks, which orient the hook point toward and perpendicular to the hook shaft, have been promoted as a means to limit fishing induced mortality (Cooke and Suski, 2004;

Cooke et al., 2005). Conservation benefits of using circle hooks over conventional styles are that fish are more commonly externally hooked in the mouth or jaw, reducing damage associated with deep gut hooking, which is more prevalent when using natural bait (Cooke and Suski, 2004; Lukokovic and Uphoff, 2007). Hooks set externally are easier to remove which reduces handling time and air exposure, ultimately limiting injury and associated physiological stress (Cooke and Suski, 2004; Bartholomew and

Bohnsack, 2005). The increased use of circle hooks in the Minas Basin Striped Bass fishery indicates that local recreational anglers will adopt methods of best practice without direct regulation.

Results highlighted significant levels of catch and release activity within the

Minas Basin recreational fishery; >95% of Striped Bass angled and released at the study site were under the size of legal retention (<68 cm TL). This corresponds well with SRFC results, which indicated that release rates of >90% and >95% occurred in 2005 and

2010, respectively (DFO, 2007; 2012). Catch and release practices are generally viewed as having positive conservation benefits (Bartholomew and Bohnsack, 2005; Cooke and

Suski, 2005; Arlinghause et al, 2007; Cooke and Schramm, 2007) but as some mortality occurs the practice may still pose risks, particularly to small populations. In 2002, the SR stock was estimated, by a partial census, to range between 18000-27000 bass (Douglas et al, 2003). Small populations may be particularly susceptible to cumulative impacts of catch and release activity (Post et al., 2002; Woodward and Griffin, 2003; Cooke et al.,

2013; Kerns et al., 2012).

Discussions with anglers during sampling activities indicated that many tag recaptures went unreported; tag reporting rate is thus underestimated in this study.

Despite this, individual Striped Bass were reported as being caught and released as many as 6 times. This result highlights a high degree of site fidelity and the potential risks imposed to undersized fish due to multiple captures and release. As anglers repeatedly capture and release (“fish over”) undersized individuals in search of retainable size bass, the physiological effects of repeated hooking, handling, and air exposure can compound, potentially leading to mortality or sub-lethal effects (Muoneke and Childress, 1994; Bartholomew and Bohnsack, 2005; Cooke and Suski, 2005; Coggins et al., 2007).

Although catch and release (C&R) mortality of Striped Bass has not been directly investigated in Canada, studies of US stocks indicate mortality estimates ranging from 0-

46% per capture interaction (Muoneke and Childress, 1994; Diodati and Richards, 1996;

Lukacovic, 2001; Lukacovic and Uphoff, 2002; Bartholomew and Bohnsack, 2005; Millard et al., 2005). A conservative C&R mortality estimate of 9% per interaction (Diodati and

Richards, 1996) is cited commonly in saltwater Striped Bass management (Richards and

Rago, 1999; AFSMC, 2013). Catch and release studies indicate that mortality is often delayed post-release, an outcome which is generally unknown to the recreational angler

(Mouneke and Childress, 1994; Bettoli and Osborne, 1998; Nelson, 1998). In addition to potential mortality, C&R activity may also inflict sub-lethal effects, which cumulatively, can impact at a population level (Stockwell et al., 2002; Bartholomew and Bohnsack,

2005; Coggins et al., 2007). Sub-lethal effects may reduce or delay individual growth

(Stockwell et al., 2002 ), reduce reproductive success (including delayed or failed spawning, see Charmichael et al., 1998 ), diminish fitness, and alter behavior leading to increased susceptibility to predation or disease (Tamasso et al., 1996; Bettoli and

Osborne, 1998).

Ultimately, a mechanism is needed to monitor the number of recreational anglers targeting Striped Bass and their subsequent exploitation of the population. A saltwater angling license or registry, similar to those mandated in many US states, has been considered by DFO as a means to collect data on fishing effort (G. Stevens, DFO, pers. comm.). Critiques have focused on the extensive timeframe and costs to both implement and enforce these systems, and a management philosophy debate over whether a blanket marine sport fishing license would be preferred over species-specific licensing. Perhaps a more time sensitive approach would be to consider granting the

Striped Bass sport-fish status, requiring all anglers targeting Striped Bass to purchase a provincial angling license. Further, a tag system, similar to programs used in Nova Scotia for Atlantic salmon, could then be implemented. A two part license/tag system would require extensive cooperation between federal and provincial fisheries agencies, but would provide a feedback mechanism for fishery managers, while permitting continuation of the recreational fishery, and serving to further limit overall retention levels. Without this information, reliable determination of mortality due to fishing retention is not possible.

2.4.2 Population Characteristics

Mean fork length of angled bass decreased over the study period, which is most likely attributed to differences in relative sample size between survey years and the time at which bass were sampled within the summer growth/feeding season. The consistent dominance of 3 and 4 year age classes, across all years (75% of all bass surveyed), is similar to results reported by Rulifson et al. (2008). Few retainable size fish

(>68cm TL) were observed in this study. Rulifson et al. (2008) sampled no bass >61cm FL during 1985-1986 iBoF surveys; the absence of older larger bass coincided with reduced

Striped Bass stocks throughout the species range (Rulifson and Dadswell, 1995).

Anecdotal reports from anglers in 2010-2012 indicated that the number of large bass within the SR system has increased (Duston, 2010 in COSEWIC, 2012; MacInnis, 2012).

This suggestion was further supported by observations of Bradford and Leblanc (2011) who indicated that spawner abundance within the SR stock has increased since 2001, with a greater representation of adult bass over 60cm FL. It is therefore assumed that large Striped Bass were present within the Minas Basin in much greater numbers than indicated by this study.

Several potential factors may have contributed to the low numbers of large bass captured by anglers at Grand Pré. Firstly, Striped Bass are known to be light sensitive

(Setzler et al., 1980), and may select deeper water during daylight periods to avoid light exposure (Ng et al., 2007). Because deep water channel habitat is less accessible to shore-based anglers, larger bass may not have been susceptible to capture.

Furthermore, if bass prefer to feed during periods of lower light their capture

31 probability may have also been reduced by limited night time sampling. Thermal constraints may also influence the presence of Striped Bass (Coutant, 1985; Coutant and

Benson, 1990; Nelson et al., 2010). Minas Basin waters are well mixed and are naturally warmed throughout the summer due to transfer of solar heat from sun baked mudflats to returning tidal waters (Parker et al., 2007). Adult Striped Bass avoid temperatures in excess of 25°C (Coutant, 1986; Nelson, 2010), and likely select temperatures <20°C

(Collette and Klein-MacPhee, 2002). Juvenile and sub-adult Striped Bass appear to be more tolerant of temperature extremes and may persist in temperatures reaching 30°C

(Setzler et al., 1980; Coutant, 1986) which may explain their seemingly continual presence in the intertidal zone at Grand Pré during summer survey periods. Thermal habitat partitioning may influence the spatial and temporal distribution of striped bass and thus have important implications relative to habitat quality, food availability, and fish health (Coutant, 1985; Coutant, 1987; Colette and Klein-MacPhee, 2002).

The diet of Striped Bass is known to shift to an increased level of piscivory with age (Rulifson and McKenna, 1987; Dadswell and Rulifson, 1995). Large piscivorous bass would be expected to feed pelagically, which would also decrease the probability of encounter with baited hooks presented on the bottom in near-shore areas. Large bass can be captured in intertidal weirs and tidal river mouths of Minas Basin during periods when prey fish, largely Alosines, aggregate during spring spawning runs. However, following such periods, it is likely that larger Striped Bass disperse in pursuit of prey, thus making them less accessible for capture in the near-shore recreational fishery. As

Striped Bass age they are expected to undertake longer range migrations from their

32 home estuary, and upon reaching sexual maturity bass can be expected to stray increasingly further seaward (Kohlenstein 1981; Rulifson and Dadswell 1995; Secor and

Piccoli, 1996). These size-dependent movements may have also limited capture of adult

Striped Bass at the Grand Pré sampling site.

Aging analysis indicated that Striped Bass of the same age differed by as much as

20cm in length, a result also reported by Rulifson et al. (2008). Natural variation in size between individuals of the same age class can be exaggerated by size differences between fish collected at the beginning versus the end of the survey season (e.g.,

Setzler et al., 1980), but could also be indicative of size differences between sexes, differences between local and migratory stocks, or variation in growth imparted by sub- lethal effects of catch and release (Stockwell, 2002). Understanding growth rates variation within and between stocks of Striped Bass assists prediction of when bass of certain year classes will reach legal size retention limits and has implications for sexual maturation, fecundity, recruitment, and migration.

Recruitment success of Striped Bass is variable and largely driven by environmental factors and adult demographics (Setzler et al., 1980; Ulanowicz and

Polgar, 1980; Secor and Houde, 1995). In recent years, US Striped Bass stocks have rebounded following crashes during the 1980-1990s (Field, 1997; AMSFC, 2013). To protect intermittent year classes within a recovered population from overfishing, US managers have recently further reduced fishing mortality rate targets from F = 0.3 to F =

0.2 (Richards and Rago, 1999; AMSFC, 2013). Currently, biological reference points

33 relative to fishing/by-catch mortality and spawning stock biomass do not exist for the

BoF population. Management actions, including elimination or restriction of Striped

Bass as by-catch in commercial fisheries, bag limits, and increased retention size limits in the recreational fishery, have been interim protective solutions in the face of insufficient data for local Striped Bass populations (Jessop, 1990; Douglas et al, 2003; COSEWIC,

2012).

Estimates of total instantaneous mortality (Z, fishing + natural mortality) obtained from the current study were found to increase from Z = 0.42 in 2008 to Z =

0.77 in 2010. Rulifson and Dadswell (1995) reported Z values for the Bay of Fundy striped bass population ranging from 0.15-0.23. While data are presently limited to further define and partition levels of Striped Bass mortality due to fishery or natural sources, these values may indicate potential risks of overfishing particularly with increasing numbers of anglers and intermittent recruitment. Careful interpretation is required as estimates can be impacted by the sampling methodology used. In this study, capture of older age classes was limited, and bass 2 years and younger were not fully recruited to the fishery. These factors limit the number of year classes present in the analysis and therefore the number of data points used to determine total instantaneous mortality. As the overall sampling effort and sample size examined in each year varied, it is difficult to make comparisons among years. It is probable that increasing levels of mortality indicated that a successful year class reached legal size, and resulted in many large fish being retained. However, maximum ages recorded in each year of this study did not follow the expected age distribution that should have resulted from the

34 suspected dominant 1999 year class (COSEWIC, 2004; Bradford et al., 2012). The 1999 year class, ranging in age from 9-11 years during our study, would have been fully recruited to the retention size of the recreational fishery.

2.4.3 Recaptures and Movement

Conducting tagging activities alongside and with assistance of local recreational anglers made it possible to encourage the return of tags and reinforce study objectives.

Fishery dependence, or reliance on recreational anglers and commercial fishers to report tags, is a general concern in all mark-recapture studies, as lack of reporting has serious implications for interpretation of study results (Pine et al., 2003). A direct measure of reporting rate is not known for this study. While the overall recapture rate of 22.5% is comparable to values reported from similar studies conducted locally

(Rulifson et al., 2008; Bradford et al., 2012), it is known that recaptured bass were underreported. During sampling events many anglers, despite awareness of the tagging program and ongoing positive interactions, indicated that they had captured tagged fish but did not record information. Anglers indicated that small print on tags, algal fouling on tags, and lack of writing instruments to record tag numbers, as factors in non- reporting.

Survey effort decreased over the course of the study. Reduced recapture rates can be attributed to reduced survey effort, which may have also been compounded by the reduced level of interaction with anglers. No monetary incentive was provided for reporting of recaptures. Further, the consistent presence of tagged fish may have

35 limited interest of anglers in reporting recaptures at the Grand Pré survey location.

Several commercial fishers were supportive of the study and provided recapture reports, but Striped Bass recaptured as a portion of by-catch in commercial fisheries (i.e. intertidal weir, drifted and fixed gill net, jump nets) was probably underreported. As the retention of Striped Bass by-catch is currently either highly restricted or illegal, some commercial fishers may have been reluctant to report the presence of tagged non- target by-catch for fear of further restrictions being imposed on their operations.

In general, tag returns were received from a small geographic area largely contained within Minas Basin and its river estuaries, with 81.9% of all recaptures being returned from the initial site of tagging at Grand Pré, NS. Within year recaptures indicated that bass remained within a small geographic area throughout the summer feeding period (June-September), similar to results reported by Ng et al (2008).

Alternatively, bass make short distance migrations within Minas Basin, but return to the same sites multiple times during a single season, exposing them to repeated angler capture. Recapture histories of fish recorded over multiple years at Grand Pré also indicated inter-annual site fidelity with tagged fish being recaptured at similar times (i.e. same month). Within-season site residency and inter-annual site fidelity suggest a limited movement range of sub-adult Striped Bass during summer and early fall. These findings are important considerations as areas of critical habitat for BoF Striped Bass are further defined (DFO, 2014).

The present study showed a high degree of site fidelity at Grand Pré, with few recaptures on the northern shore of Minas Basin. Rulifson et al. (2008) showed a similar site fidelity pattern for sub-adult bass tagged on the northern shore of Minas Basin.

Interestingly, tagged bass that exited overwintering grounds (Shubenacadie-Grand Lake,

NS) in spring have been recaptured from both the northern and southern regions of

Minas Basin (Bradford et al. 2012). Collectively, these results indicate that both the timing of tagging and tagging location are important in the analysis of movement patterns. Any future studies should tag Striped Bass during periods of pre- and post- spawning to better examine dispersal of striped bass within Minas Basin. Future studies conducted in Minas Basin should also include multiple tagging sites to limit spatial bias.

The migratory extent of tagged Shubenacadie Striped Bass remains largely unknown, but has been reported to extend into the Gulf of Maine and along the southern Atlantic coast of Nova Scotia (Bradford et al., 2012; DFO, 2014). Conventional mark-recapture tagging was unable to provide the level of spatial and temporal resolution necessary to examine movements through Minas Passage into the outer Bay of Fundy, in part because of low fishing activity in these regions coupled with limited tagging of large bass, which would be expected to exhibit the longest range migrations.

The contribution of migrant Striped Bass originating from US stocks has long been of interest within the Bay of Fundy. Past tagging (Rulifson and Dadswell, 1995;

Rulifson et al., 2008), and genetic studies (Wirgin et al., 1993; Wirgin et al., 1995) have indicated overlap of BoF Striped Bass with migrants from other stocks during summer

37 feeding as well as shared use of overwintering sites, but have not indicated inter-stock spawning (COSEWIC, 2012). It is expected that the presence of US migrants and level of stock interaction varies inter-annually, presenting further obstacles for Striped Bass management (DFO, 2006b; COSEWIC 2012; DFO, 2014).

Rulifson et al. (2008) reported that, of all Striped Bass tagged in the Minas Basin and Cobequid Bay during 1985-1986 (N = 1866 Striped Bass; ≤61cm FL), only 0.37% (N =

7) were recaptured at sites within the United States. In a more recent report, Bradford et al. (2012) documented the 1999-2001 departure of 1862 tagged Striped Bass from the known overwintering area of Shubenacadie-Grand Lake, NS. There were no reports of tag returns from the United States up to and including the year 2005 (Bradford et al.,

2012). Striped Bass tag returns in the present study include only three recaptures outside of Minas Basin but these were from within the Bay of Fundy system. There were no detections of bass tagged elsewhere and thus no evidence of immigration from outside stocks. Inferences that US migrant fish are present in numbers significant enough to directly impact upon population assessment and to alter perceptions of local stock health within the recreational and commercial fishing communities have been common (Rulifson and Dadswell, 1995; Rulifson et al., 2008; Bradford et al., 2012), but may not be warranted.

Estimates of population abundance at the Grand Pré site were similar between years, ranging between 1500 and 2520 Striped Bass. Sequential estimates in 2008 and

2009 seasons indicated very similar patterns of decreasing abundance over the

38 monitored angling period which is likely indicative of an open population. Change in the estimated population size and its distribution between sequential sampling events is a measure of the information added by the sample (Gazey and Stanley, 1986). The patterns observed in years 2008 and 2009 may provide further evidence to support differential habitat use in Minas Basin, where population abundance during the beginning of the season is variable and indicative of the presence of dispersive/migratory contingents within the intertidal zone. Later in the season, the departure of dispersive/migratory contingents increases the consistency between sequential interval estimates, which is expected to be indicative of the presence of a localized resident contingent. Body size appears to be the primary feature defining dispersive and resident Striped Bass groups, but these behavior patterns are likely further influenced by feeding preferences, and thermal tolerance. Contingents of

Striped Bass which exhibit differential habitat use and migration patterns will have differing levels of susceptibility to the recreational fishery, and potentially to other anthropogenic impacts. Further study to enhance understanding of such contingent behavior within the BoF is warranted as it may pose important implications for future management.

2.4.4 Conclusions and Recommendations

This study serves as the first multi-year assessment of recreational angling in the

Minas Basin. This three year survey indicated high rates of catch and release in the

Grand Pré intertidal recreational fishery, with limited capture of retainable size bass

(≥68cm TL). Bass angled from the intertidal zone were dominated by 3- and 4-year olds,

39 representing >60% of the catch in each study year. Over 80% of recaptures (which are known to be under-reported) were from the site of initial tagging at Grand Pré.

Recapture results indicated both site residency and inter-annual site fidelity of sub-adult

Striped Bass. Multiple recapture records indicated that individual bass were recaptured up to six times. Three recaptures were reported outside of Minas Basin, but still within the BoF, indicating travel through Minas Passage.

This study has highlighted many of the challenges, including the extreme physical conditions within the inner Bay of Fundy system that continue to limit collection of long- term data for BoF Striped Bass. Consequently, many important knowledge gaps remain.

Given the limitations of conventional mark-recapture tagging, and the need for higher resolution information on the distribution and movements of Striped Bass to address management questions, it is recommended that alternative monitoring options be considered. Electronic techniques, such as acoustic tagging and active acoustic monitoring, should be investigated as potential methods that could be implemented to support/enhance ongoing monitoring.

In Chapter 3 the detection range and efficiency of VEMCO acoustic telemetry technology will be investigated within Minas Passage, NS. This will serve as a first step in determining the application potential of acoustic telemetry to monitor movements of

Striped Bass into and out of the Minas Basin.

2.5 TABLES

Table 2-1. Catch statistics of self-reporting, provincially licensed, Nova Scotia resident, Striped Bass anglers (Data Source: DFO, 1994; 1997; 2003; 2007; 2012; NSDFA, n.d.).

Year Licence Total Caught Retained CPUE Percent Holders Days (day) Retained targeting Fished (%) Striped Bass 1990 NA NA 20695 11248 NA 54.3 1995 NA NA 28002 18202 NA 65.0 2000 4299 33873 30790 1862 0.908 6.0 2005 5626 70740 123009 12035 1.736 9.7 2010 7248 68861 94700 3710 1.356 3.9

Table 2-2. Summary table of Striped Bass sampling and tagging efforts and estimated population characteristics for years 2008-2010.

Study Year 2008 2009 2010 Months Sampled June - October May - October June - August Striped Bass Angled 545 275 246 Mean FL (±SD) (cm) 40.4 (10.4) 38.4 (9.6) 35.7 (6.7)

Total Effort (Rod Hours) 1750.7 992.6 454.9 CPUE (Fish/Rod Hour) 0.31 0.27 0.54 Retainable Size (≥68cm TL) 15 9 1 Retained 10 3 1 Retainable per Rod Hour 0.0086 0.0091 0.0022

Total Examined 575 308 304 Number Tagged (all sources) 529 301 296 Within Year Recaptures 135 41 31 Total Recaptures NA 140 102 Yearly Exploitation Rate (u) 0.25 0.13 0.10 Total Instantaneous Mortality (Z) 0.42 0.7 0.77 Annual Survival Rate (S) 0.65 0.49 0.46 Annual Mortality Rate (A) 0.34 0.50 0.53

Number Aged 518 264 234 Age Range 2-10 2-9 2-9

Mean Age (±SD) 4.2 (1.6) 4 (1.5) 3.6 (1.2) Median Age 3.7 4 3

Table 2-3. Striped Bass catch and release (C&R) mortality estimates calculated from data contained within the Survey of Recreational Fishing in Canada (SRFC) reports (DFO, 1994; 1997; 2003; 2007; 2012; NSDFA, n.d.), as well as data from the present study. The number of catch and release mortalities are estimated assuming a 9% level (Diodati and Richards, 1996). Note that these are point estimates, and do not take into account individual recapture histories, and are provided only as approximate reference values.

Year Data Source Caught Retained Released Point Estimates of C&R Mortality - assuming 9% (Diodati and Richards, 1996) 1990 SRFC 20695 11248 9447 850 1995 SRFC 28002 18202 9800 882 2000 SRFC 30790 1862 28928 2603 2005 SRFC 123009 12035 110974 9987 2010 SRFC 94700 3710 90990 8189 2008 this study 545 10 535 48 2009 this study 275 3 272 24 2010 this study 246 1 245 22

Table 2-4. Distribution of recaptured Striped Bass recovered from all locations by year, relative to year of initial tagging.

Recovery Year

Tagging Year 2008 2009 2010

2008 135 99 34

2009 41 37

2010 31

Table 2-5. Number of Striped Bass recaptures reported during each survey year by reporting source.

Source 2008 2009 2010

Recreational Fishery 76 67 28

Intertidal Weir – North Shore 0 4 0

Intertidal Weir – South Shore 0 2 0

Survey Team 59 67 74

Total 135 140 102

Table 2-6. Distribution of cumulative multiple recapture counts for individual Striped Bass pooled for 2008-2010.

Recapture # n 1 174 2 53 3 17 4 3

5 4 6 2

Table 2-7. Striped Bass tag returns, pooled for 2008-2010, indicating location and season of capture. Formatted as in Rulifson et al. (2008).

Season Location Spring Summer Fall (May-Jun) (Jul-Aug) (Sept-Nov) Minas Basin – North Shore 4 0 0 Minas Basin – South Shore 40 179 124 Cobequid Bay 3 3 3 Shubenacadie/Stewiacke 16 1 0 Watershed BoF – Seaward of Minas Passage 0 1 2

Table 2-8. Summary of sequential Striped Bass population size estimates for the immediate area of the Grand Pré tagging site.

Year Duration Total Total Mode Median Lower Upper Intervals Marks 95% CI 95% CI

2008 Jun 27 – Sep 26 14 443 1500 1500 1200 1875 2009 Jun 10 – Sep 23 16 712 2250 2175 1800 2775 2010 Jun 9 – Aug 25 12 943 2520 2520 2120 3080

2.6 FIGURES

Figure 2-1. Locations of the five known Canadian Striped Bass spawning stocks. Extant stocks are indicated by solid closed circles (Shubenacadie, and Miramichi Rivers), and extirpated stocks (St. Lawrence, St. John, and Annapolis Rivers) are indicated by open circles. Dotted lines indicate the known habitat range of Striped Bass, while dotted lines interspersed with question marks (?) indicate that the use of habitat beyond that area is currently unknown. (Figure modified from DFO, 2006b).

Figure 2-2. Map of the southern portion of the inner Bay of Fundy indicating locations of major water bodies. The primary Striped Bass sampling location, Grande Pré, NS (“The Guzzle”) is indicated by a black diamond. Locations of commercial intertidal fishing weirs, used for intermittent sampling, are indicated by black triangles.

Figure 2-3. Daily CPUE (fish/rod/hour) indicated by month during years 2008-2010. Dark grey bars, light grey bars, and white bars represent survey years 2008, 2009, and 2010, respectively. Open circles denote outliers. The number of tides sampled within each month is indicated above each bar.

Figure 2-4. Daily catch per unit effort (fish/rod/hour) relative to daily tidal range (m). Tidal range was calculated as the difference between the preceding low water elevation and the predicted high water elevation of the high tide surveyed. The number of tides sampled within each range bin is indicated above each bar. Open circles denote outliers.

Figure 2-5. Daily CPUE (fish/rod/hour) indicated by hour of day in which the high tide occurred, pooled for years 2008-2010. Open circles denote outliers. The number of tides sampled within each hour is indicated above each bar. Surveys during night-time were limited.

60 Percent Frequency 40 (%) 20

0 Circle Standard (J) Worm Treble Hook Type

25 2008 2009 20 Percent 2010 Frequency (%) 15

0 15 20 25 30 35 40 45 50 55 60 65 70 FL (cm)

Figure 2-7. Length frequency of Striped Bass angled from Minas Basin during 2008 (dark grey bars), 2009 (medium grey bars), and 2010 (light grey bars).

30 2008 25 2009 Percent 2010 Frequency 20 (%) 15

0 2 3 4 5 6 7 8 910 Age (yrs)

Figure 2-8. Age frequency of Striped Bass angled from Minas Basin during 2008 (light grey bars), 2009 (dark grey bars), and 2010 (medium grey bars).

Figure 2-9. Observed length (FL, cm) at age (yr) and the predicted von Bertalanffy growth curve of Striped Bass (N= 1022) angled from Minas Basin during 2008-2010. Von Bertalanffy equation parameters: L∞ =

85.4cm, K = 0.13, t 0 = -1.07.

Figure 2-10. Sequential Bayes population estimates of Striped Bass based on mark-recapture data within the immediate area of Grand Pré, NS tagging site. Solid black circles indicate the median estimated abundance determined from each 7 day sequence, and whiskers indicate 95% confidence intervals of the estimate.

2.7 APPENDIX

Appendix 2-A. Informational posters placed at common fishing locations as well as other areas that anglers frequent (post offices, gas stations, convenience stores, tackle shops, etc.) in communities throughout the study area. Posters outlined the tagging program, indicated the anatomical positioning and description of tags, and provided contact information to report recaptured fish.

Appendix 2-B. 2005 Nova Scotia Striped Bass angling statistics reported by county, as per the 2005 Canadian Recreational Angling Survey (DFO, 2007; DFO, unpublished data).

Year County Total Days Caught Retained CPUE (day) Proportion Fished Retained 2005 Annapolis 2971 2234 58 0.752 0.026 2005 Antigonish 405 892 0 2.202 NA 2005 Cape Breton 187 12741 6359 68.134 0.499 2005 Colchester 26127 33679 538 1.289 0.016 2005 Cumberland 1767 1426 0 0.807 NA 2005 Digby 608 1402 0 2.306 NA 2005 Guysborough 0 0 0 NA NA 2005 Halifax 7217 14483 390 2.007 0.027 2005 Hants 15823 34214 2439 2.162 0.071 2005 Inverness 590 1181 369 2.002 0.312 2005 Kings 13976 19889 1223 1.423 0.061 2005 Lunenburg 333 0 0 NA NA 2005 Pictou 0 0 0 NA NA 2005 Queens 0 0 0 NA NA 2005 Richmond 37 36 0 0.973 NA 2005 Shelburne 109 601 601 5.514 1.000 2005 Victoria 0 0 0 NA NA 2005 Yarmouth 589 234 58 0.397 0.248 2005 Total 70739 123012 12035 1.739 0.098

Appendix 2-C. 2010 Nova Scotia Striped Bass angling statistics reported by county, as per the 2010 Canadian Recreational Angling Survey (DFO, 2012; DFO, unpublished data).

Year County Total Days Caught Retained CPUE (day) Proportion Fished Retained 2010 Annapolis 6095 425 114 0.070 0.268 2010 Antigonish 58 266 0 4.586 NA 2010 Cape Breton 1639 0 0 NA NA 2010 Colchester 17045 18823 461 1.104 0.024 2010 Cumberland 10309 23915 1285 2.320 0.054 2010 Digby 373 114 0 0.306 NA 2010 Guysborough 20 120 3 6.000 0.025 2010 Halifax 6463 4582 277 0.709 0.060 2010 Hants 10878 10577 1074 0.972 0.102 2010 Inverness 216 865 0 4.005 NA 2010 Kings 11158 25163 429 2.255 0.017 2010 Lunenburg 440 287 0 0.652 NA 2010 Pictou 68 68 0 1.000 NA 2010 Queens 198 0 0 NA NA 2010 Richmond 670 0 0 NA NA 2010 Shelburne 0 0 0 NA NA 2010 Victoria 0 0 0 NA NA 2010 Yarmouth 3230 9496 67 2.940 0.007 2010 Total 68860 94701 3710 1.375 0.039

CHAPTER 3 - Detection range and efficiency of VEMCO acoustic telemetry technology in the hyper-tidal Minas Passage, Bay of Fundy

3.1 INTRODUCTION

Since its inception nearly 60 years ago, the field of underwater acoustic telemetry has advanced rapidly, becoming a tool of choice for biologists in the study of mobile aquatic animals (Stasko and Pincock, 1977; Vogeli et al., 2001; Cooke et al., 2004;

Heupel et al., 2006; Pincock et al., 2010). During this time, technological advances have improved performance and increased application potential of acoustic telemetry techniques. Advances include: extension of transmitter battery life permitting longer studies, improved telemetry sensors allowing for collection of environmental and physiological data, advanced transmitter coding schemes allowing for large numbers of unique transmitters to be deployed within an individual study, and perhaps most importantly reductions in the size of electronic components permitting application for tracking species and life stages previously considered too small for tagging (Heupel et al., 2006; Pincock et al., 2010).

Despite the widespread use of telemetry techniques, few studies have thoroughly investigated the efficiency of acoustic telemetry equipment (Heupel et al.,

2006; Simpendorfer et al., 2008; Kessel et al., 2014). Range and efficiency testing have been identified as fundamental diagnostic tools and ultimately affect the interpretation and statistical analysis of animal detection data (Heupel et al., 2006; Heupel et al., 2008;

Simpendorfer et al., 2008; Payne et al., 2010; Pincock et al., 2010; Melnychuk, 2012a).

As detection range and efficiency are largely dependent on the physical and

54 environmental conditions of the study system, site specific and temporally comprehensive testing is recommended (Heupel et al., 2006; Pincock, 2009; Pincock et al., 2010).

Passive acoustic telemetry systems consist of two primary components: transmitters (tags) which serve as the sound source and hydrophones which receive the signals. The tags emit unique coded acoustic pulse sequences identifying the specific tag which is associated with an individual animal carrier, while receivers passively detect, time stamp, and record transmissions (Hobday and Pincock, 2011; Pincock and

Johnston, 2012). Both components of the telemetry system are susceptible to interfering physical and environmental factors which limit operational range and reduce detection efficiency. Such factors include: tag to receiver distance, sound absorption, reflection (echoing), blockage, and interfering noise originating from a variety of sources

(Heupel et al., 2006; Pincock and Johnston, 2012).

The propagation distance of a transmission is directly related to the output power level of the tag (Cooke, 2004; Pincock and Johnston, 2012; Melnychuk, 2012b). In water, sound intensity decays, through geometric spreading, as a function of the square of the range (Pincock et al., 2010; Gjelland and Hedger, 2013), providing an upper bound to transmission distance. Maximum range is reduced by sound absorption which is directly related to the conductivity, temperature, turbidity and water column depth at the study site (Voegeli and Pincock, 1996; Pincock et al., 2010; Pincock and Johnston,

2012). Thermal or salinity stratification can cause sound waves to reflect off stratified layers, preventing signal penetration or producing sound reflections and multipath

55 conditions (Singh et al., 2009). Further, acoustic signals can be physically obstructed when the line-of-sight between tag and receiver is blocked due to bathymetry and other bottom or water column features (e.g. rocks, ledges, logs, submerged vegetation), or by features of mooring design and receiver/tag orientation (Clements et al. 2005; Heupel et al., 2006; Welch et al., 2012).

Interfering noise is a significant factor which can diminish the overall performance of acoustic telemetry equipment (Voegeli et al. 2001; Heupel et al. 2006;

Simpendorfer et al. 2008). Common interfering noise sources have been identified as: weather (wind, precipitation), environmental noise (water currents, waves, entrained air bubbles, shifting substrate), biological (biofouling, sound producing animals), or anthropogenic (boat traffic, underwater construction, submerged infrastructure)

(Thorstad et al., 2000; Lacroix et al., 2005; Heupel et al. 2006; Heupel et al. 2008;

Simpendorfer et al. 2008; Melenychuk, 2012; Gjelland and Hedger, 2013).

While relatively few studies have investigated detection range and performance of passive tracking equipment, such studies have rarely been done in areas of high current flow. Several directed range and detection efficiency studies have indicated water movement is an important predictor of detection efficiency (Simpfendorfer et al.,

2008; How and Lestang, 2012; Gjelland and Hedger, 2013, Mathias et al., 2014), however, these studies were not from high flow areas. Telemetry studies conducted in the Columbia River reported current speeds in excess of 2m/s during periods of ebbing tide (Clements et al 2005; Titzler et al 2010), however, these studies focused primarily on mooring strategies for high current sites rather than investigations of signal

56 detection efficiency. High levels of noise induced by current flow, turbulence, air entrainment, turbidity and suspended material are factors characteristic of high flow, tidally dominated systems; all have been identified as problematic for acoustic tracking studies (Clements et al., 2005; Heupel et al, 2006; Titzler et al., 2010).

The establishment of recent renewable energy targets for Nova Scotia (40% of the Provincial electricity supply by 2020) has prompted renewed efforts to harness tidal energy from the Bay of Fundy (NSDoE, 2010). To help meet these targets, the Fundy

Ocean Research Center for Energy (FORCE) was established in 2009. It is a tidal in- stream energy conversion (TISEC) device test site located in the northern region of

Minas Passage. The extreme hyper-tidal environment of Minas Passage has attracted attention to the area for energy extraction, but is acoustically noisy. Hydrophone recordings indicate that background noise levels vary considerably with tidal phase, amplitude, and location (Martin et al., 2012; Porskamp, 2013). Factors contributing to background noise include a tidal range of up to 13m which generates surface current speeds of up to 6m/s (Karsten et al., 2008), suspended sediment loads >10mg/L

(Envirosphere, 2009), bed load transport (Fader, 2009), turbulent flow, and significant entrained air, winter ice, and other floating debris (Melvin and Cochrane, 2014); all present challenges for conducting acoustic research. The degree to which acoustic telemetry can be used to address questions related to movement of mobile organisms in high flow areas targeted for tidal in-stream energy conversion (TISEC) device testing is addressed in this study.

This chapter describes the use of an array of moored passive acoustic receivers, and moored test tags, to investigate detection efficiency and transmission range under highly variable, tidally dominated conditions within Minas Passage, Nova Scotia, Canada.

The objectives of this study were: 1) to develop a suitable mooring design for long term deployment (up to 1 year) in Minas Passage, 2) determine the relationship between transmitter power output and detection range, and 3) investigate detection efficiency as a function of tidal stage and current speed. Understanding these relationships is of fundamental importance in the design of passive tracking studies that focus on determining the potential risk of turbine-fish interactions in a tidal race.

3.2 METHODS

3.2.1 Study Area

This study was conducted within the Minas Passage, Bay of Fundy, a 6km wide constriction that separates Minas Channel from Minas Basin (Figure 3-1). The Minas

Passage has been identified as one of the preeminent resources of tidal energy in the world (EPRI, 2006; Karsten et al., 2008).

The extreme hyper-tidal range (up to 13 m) is generated through a combined effect of the funnel shape of the Bay of Fundy and the natural tidal resonance period of the Bay of Fundy–Gulf of Maine system which is slightly larger than the 12.42 hour period of the dominant semi-diurnal lunar tide (Garrett et al., 1972; Karsten et al.,

2008). Tidal forcing through Minas Passage generates flows up to 106 m 3/s during tidal exchange, with sustained depth-averaged tidal currents of up to 3.28m/s (Figure 3-2,

Karsten et al., 2008). Surface currents approach velocities of 6m/s during spring tides

(Oceans Ltd., 2009), and decrease with depth. Ebb and flood tides are asymmetrical with respect to current velocity in Minas Passage (Karsten, 2008). Flood currents are generally faster and more turbulent than ebb tides which are relatively uniform and laminar. Tidal flushing and turbulence within the system causes strong vertical mixing and prevention of temperature and salinity stratification.

The bathymetry of Minas Passage is highly variable. Depths of >120 m are found in the highly scoured central and southern portions of the Passage. The shallower northern area is the location of the FORCE test site (1.6 x 1.0 km area of Crown Leased seabed) and is characterized by a dogleg shaped plateau of volcanic basalt with relatively uniform bathymetric relief, and depths of approximately 30-55m MWL

(Envirosphere, 2009). On November 12 th , 2009, an OpenHydro TISEC turbine (1MW,

10m diameter, 12 blades, ducted) was deployed on a 400 tonne tripod gravity base within the FORCE lease area. The device was installed north of the receiver stations for this study, and approximately 120m from receiver station 6. The turbine remained in place for over a year but was operational for only the first three weeks following deployment (FORCE, 2011).

3.2.2 VEMCO Transmitter and Receiver Technology

The acoustic telemetry system used in this study consisted of receivers and transmitters manufactured by VEMCO (Halifax, NS, www.vemco.com). The VEMCO

VR2w hydro-acoustic receiver is passive, omnidirectional, single channel (69kHz), and functions to autonomously detect, time stamp, and store coded signals emitted by

59 acoustic transmitters. Acoustic transmitters (or tags) are generally attached to fish and other marine animals most often by surgical implantation or external attachment. Tags emit specific coded ping sequences which are decoded by acoustic receivers to identify the specific carrier animal, the date and time of detection, and any sensor data (i.e. depth, temperature, acceleration) that tags may be programmed to provide.

3.2.3 Instrument Mooring Design

Seven receivers were deployed with subsurface floats and independent anchor weight moorings comprised of 5cm diameter steel chain links, with each mooring totaling about 200kg (Figure 3-3). A 2m length of 9mm diameter galvanized steel chain was wrapped through the central and end links of the anchor weight, and then shackled to itself using a 10mm galvanized steel safety shackle. A section of 6mm stainless steel cable was then woven through the anchor links, passed through the main shackle, with ends joined by two 9mm galvanized wire rope clips. These actions condensed the chain links into a compact mass while leaving 1m of galvanized chain free to act as a riser. The

1m riser chain was then attached to the terminal end of an 875-TD shallow water acoustic release (Teledyne Benthos, North Falmouth, MA, USA) using an 8mm stainless steel drop link style D-shackle. An 8mm round stainless steel shackle attached the fiberglass strong back of the acoustic release to a 3m length of 6mm diameter PVC- jacketed stainless steel cable. The ends of the jacketed cable were prepared for connection by using three stainless steel wire crimps in combination with plastic shrink wrapping to secure 8mm stainless steel eyelets at each end. The base of the jacketed cable, above the shrink wrapping, was wrapped with a base of 3M vulcanized rubber

60 tape to provide a non-slip gripping surface for attachment of a VR2w acoustic receiver.

The receiver was positioned parallel to the jacketed cable, with the hydrophone directed upward. Five, 40cm, 23kg tensile strength cable ties were used to secure the receiver to the cable, which was then covered liberally with black PVC electrical tape. A

SUBS Model B3 streamlined sub surface instrument buoy (Open Seas Instrumentation,

Musquodoboit Harbour, NS) was attached by the central mooring tension member to the top eyelet of the jacketed cable using a 9mm stainless steel safety shackle. Each

SUBS buoy (1458mm x 375mm x 390mm, Drag Coefficient = 0.6) housed three, 13” diameter, VINY trawl floats which contributed a total of 60kgs of buoyancy in saltwater.

3.2.4 Receiver and Tag Array Design

The receiver array was designed with assistance from VEMCO staff to examine the application potential of the VEMCO Positioning System (VPS) in Minas Passage. The

VPS system generates three dimensional positions from acoustic tag detections by triangulating the minute (millisecond) time differences in detection arrival times between nearby receiver stations. The system requires that receiver stations be closely spaced and that synchronization (sync) tags be co-deployed on receiver stations or moored separately at known positions to calculate distances between tags and receivers through triangulation. No fish were tagged during this test: the function of the VPS system was to calculate the exact distances between the receiver stations for detection range determination.

Seven VEMCO VR2w acoustic receivers were positioned in a linear array (Table 3-

1), in-line with the dominant current flow (East-West orientation), and spanning a

61 distance of approximately 800m (Figure 3-4). Station spacing intervals were selected to examine fine scale distance resolution using low power transmitters from East to West, and longer range distance resolution with high power transmitter models in the opposite direction (West to East). Teledyne Benthos 875-TD acoustic release mechanisms were deployed as part of the mooring assembly to simplify retrieval. The

875-TD unit releases by rotating a shaft, which in turn opens an arm that holds an 8mm stainless steel drop shackle. When released, the drop shackle separated the instruments and floatation from the anchor weight and riser chain. The anchor weight and riser were sacrificed, and the flotation of the SUB buoy brought the instruments to the surface for collection.

Receiver deployments occurred on October 9, 2009 using a chartered commercial fishing vessel from the port of Hall’s Harbour, Nova Scotia. Five V16-5H synchronization (sync) tags (69 kHz, 156dB, signals emitted every 500-700s, average

600s signals, with randomized delays) were deployed on five of seven receiver stations.

Sync tags were programmed with relatively long delay periods to limit possible collision with range testing tags. Four range testing tags (V16, V13, V9, V7) were deployed to provide a representative sample of the output power and size of available VEMCO models, and were programmed with fixed delay intervals, and manually offset by 120sec to limit possible signal collisions. Range test tag specifications are outlined in Table 3-2.

Each tag was fitted with a range test cap to allow direct attachment to the jacketed stainless steel cable using 10cm, 8kg breaking strength cable ties. Upper and lower spacers of vulcanized rubber tape were applied to prevent movement of tags up or

62 down the cable. Each tag was then wrapped with black electrical tape around its base to provide support and reduce strain on the cable tie attachment.

3.2.5 Array Deployment

Fugawi Marine Navigation software (Version 4.0, Northport Systems Inc.,

Toronto, ON) was used to navigate to predetermined station positions. Fully assembled moorings were approximately 5m in height, and were lifted to the open stern using a hydraulic winch and deck boom. Once the vessel was near station the mooring weight was pushed over the stern and the 5m mooring lowered until the SUB buoy was at the waterline. These actions kept the heavy mooring mass from sliding on deck while the vessel was positioned. A final approach was made on the selected position and when passing over the point, a signal was given from the wheelhouse to engage a quick- release shackle, deploying the station. Deployment occurred near the end of flooding tide (high slack water). Difficulties encountered with attempts to keep the vessel on station were addressed by allowing the vessel to drift toward the station while making slight adjustments to the heading.

3.2.6 Array Recovery

Station recovery via vessel charter occurred on November 28th, 2009 and

December 3rd, 2009 (Table 3-1). On arrival at the station, the transducer of a UDB-9000-

LF deck box (Teledyne Benthos, North Falmouth, MA USA) was lowered over the side of the vessel. The deck box and transducer were then used to transmit a series of acoustic commands to the 875-TD acoustic release. When the wake up and status update

63 commands were properly received by the acoustic release, the release command was then transmitted by the deck box.

Stations 1, 2, 4, 6, and 7 were recovered successfully on November 26 th , 2009.

Attempts to communicate with stations 3 and 5 were unsuccessful and a second retrieval trip was conducted on December 3 rd , 2009 to collect the two remaining units.

Station 5 was recovered successfully, but several attempts to communicate with Station

3 were unsuccessful. This “lost” receiver unit was eventually recovered on June 21 st ,

2011 by a commercial fisher who found it adrift in Minas Passage. It was determined that the unit had ultimately released on an unknown date due to corrosion of the 3/8” riser chain. Further inspection indicated that the acoustic release seal had failed, flooding the unit with seawater, causing the electronics to short circuit at some point during deployment. The receiver, however, was fully operational and all experimental data were successfully recovered following a battery replacement.

3.2.7 Data Treatment and Analysis

VEMCO receiver log (VRL) files were downloaded from the recovered receivers using VEMCO User Environment (VUE) software ver1.6. A VEMCO database (VDB) file compiled all 7 receiver log files into a single database, and detection times were corrected for receiver clock drift. Data files were then converted and exported in .csv spreadsheet format. Detection histories were separated by individual tag, and the expected timing of signal transmissions was predicted using the known delay between transmissions. Expected transmission times were then cross-referenced with records of

64 successful detections at each receiver, producing a binary detection history where each signal transmission was either detected (1) or not detected (0).

Considerable variability exists with regard to testing methodology and terminology currently applied in range and detection efficiency tests (Clements et al.,

2005; Melnychuk, 2012a; Kessel, 2014). For example, Melnychuk (2012a) noted that detection efficiency has been described within the literature as the probability of detecting: 1) an individual tag transmission, 2) a tagged fish residing in an area, 3) a tagged fish migrating past a specific location, or 4) a tag present during mobile transect surveys. The terminology used in this chapter relates to the individual tag transmission, where the number of successful detections is related to the number of programmed

(expected) transmissions over a set time period.

Tidal parameter estimates were obtained through a tidal prediction model of

Minas Passage (Karsten et al., 2008; Karsten, 2011). Estimates of tidal elevation and current speed were provided for the time of each expected signal transmission.

3.2.8 Daily Performance Metrics

Receiver detection files provided four code detection parameters that could be accessed through VUE: 1) number of valid detections (D), 2) number of detected synchronization (sync) intervals (S), 3) number of rejected codes (C), and 4) number of detected acoustic pings (P). The number of valid detections is a record of each successfully decoded transmission and includes the tag ID and arrival time stamp. The sync interval comprises the beginning of an individual coded transmission, and is defined by the specific time period (msec) between the first two pings of the code

65 sequence (Pincock and Johnston, 2012). These sequences are very precise and thus uncommon in nature (Pincock and Johnston, 2012). Because the sync interval occurs once at the beginning of each transmission, it can be used as a proxy for the number of transmissions sent during the recording period (Simpendorfer et al. 2008). Rejected codes occur when the receiver recognizes a valid sync interval, as well as the correct number and spacing of pings, but ultimately the transmission does not pass the receiver’s error checking sequence. The number of pings refers to the architecture of each tag transmission and is determined by the transmitter coding. Depending upon coding parameters, VEMCO acoustic transmitters will generate between 7 and 10 individual pings per transmission; tags deployed in this study transmitted 8 pings per sequence.

Methods outlined by Simpendorfer et al. (2008) utilize three performance metrics calculated from the four detection parameters to evaluate VR2w receiver activity. These metrics include: 1) code detection efficiency (cde), 2) rejection coefficient

(rc), and 3) noise quotient (nq). Code detection efficiency (cde) is the number of detected transmissions (D) per number of sync intervals recorded (S).

cde = D/S (Eq. 3-1)

The second metric, rejection coefficient (rc), is another proportion that compare the number of rejected transmissions (C) to the number of sync intervals recorded (S).

rc = C/S (Eq. 3-2)

The final metric used to evaluate performance was noise quotient (nq), which relates the number of detected pings (P) to the number of expected pings. Expected pings are determined by multiplying the number of valid sync intervals (S) by the number of pings contained within a valid detection sequence (cl, for this study cl = 8).

nq = P – (S * cl) (Eq. 3-3)

Performance metric data was analyzed on a daily basis for 47 full days, from

October 10 through November 25, 2009. The receiver at Station 1 experienced two periods of abnormal activity, in which all parameters were one order of magnitude larger than all other stations during the same period. These abnormal periods,

November 1-5 and November 13–25, were removed from subsequent analysis; a total of 29 recording days for Station 1 were examined further.

Analyses were conducted with the statistical software ‘R’ (R Core Development

Team, 2014), and all tests assessed for significance at α=0.05. Daily performance metric values, pre- and post-installation of the OpenHydro TISEC device, were compared for significance using non-parametric Kruskal-Wallis tests. Hourly distribution of successful detections and missed transmissions were evaluated for diel patterns with Rayleigh tests of circular uniformity, using the R package ‘circular’ (Agostinelli and Lund, 2013).

3.2.9 Model of Detection Efficiency

Detection probabilities were estimated for each tag model using generalized linear models (GLM) with binomial errors (link = “logit”). Preliminary analyses identified that a logit link provided a better fit than a complimentary log-log link because it yielded a lower deviance for models with identical structure and parameters (Crawley, 2005). A pool of 24 candidate models ( mi) was constructed a priori . Models included main effects and/or interaction effects using the following explanatory parameters: tag model (TAG, categorical as: V7, V9, V13 or V16), tidal direction (TIDE, categorical as: Ebb or Flood), distance between tag and receiver (DISTANCE, categorical and discrete number, meters) and current speed (SPEED, continuous as meters per second). Model selection was performed based on the second order Akaike information criterion (AICc), which addressed model parsimony and weighed the relative adequacy of each model by formulizing the trade-off between model fit and model parameterization (Burnham and

Anderson, 2004; Crawley, 2005). The model with the lowest AICc was selected as the most parsimonious model (Crawley, 2005). Analyses were conducted in ‘R’ (R core development team, 2012), using the package ‘AICcmodavg’ (Mazerolle, 2014).

3.3 RESULTS

3.3.1 Performance Metrics

For all receivers, the number of detections logged was considerably less than the number of syncing intervals logged, as evidenced by the code detection efficiency metric (cde) (Table 3-3). Mean daily cde ranged between 0.33 and 0.46 detections/sync between receiver stations (Table 3-3 and Figure 3-5). These values indicated that less

68 than half of the expected transmissions were decoded successfully. Lowest values of cde, indicating poorest detection efficiency, were found at the receivers in the central portion of the array (stations 3, 4, and 5).

The rejection coefficient (rc) metric was found to be consistently low across all receiver stations, with daily average values ranging from 0.01 - 0.04 rejections/sync

(Table 3-3 and Figure 3-6), indicating that at most 4% of transmissions were rejected due to invalid checksum. The largest rejection coefficient values were reported from receiver stations situated in closest proximity to stations with co-located range tags; specifically stations 2 and 5.

The noise quotient (nq) metric was found to be strongly negative across all receiver stations (Table 3-3 and Table 3-7). However, average daily noise quotient of receiver station 7 was considerably less negative than the other stations. Daily average nq values ranged from (-1520) to (-3823). Similar to the cde metric, peak nq values were observed from receivers within the central portion of the array.

3.3.2 Performance Metrics Pre vs. Post TISEC Installation

Performance metrics pre- and post-installation of the OpenHydro TISEC device were evaluated at each receiver station (Figure 3-8). Kruskal-Wallis tests were performed to determine if daily metric values during pre- and post-installation conditions came from differing distributions. Significant differences between pre- and post-installation conditions were determined for the cde metric at stations 2 and 3, in the rc metric at stations 3 and 7, and in the nq metric at stations 2, 3, and 4 (Table 3-4).

Comparison tests of performance metrics were not possible for station 1 due to lack of

69 data from the post-installation period, following removal of the spurious periods described previously. No significant difference was found pre- vs. post-installation in any metrics at stations 5 or 6, the receivers in closest proximity to the Open Hydro device

(Table 3-4).

3.3.3 Diel Patterns – Detections and Missed Detections

Rayleigh tests for uniformity were conducted to determine if successful detections (Figure 3-9, top panel), as well as missed transmissions (Figure 3-9, bottom panel) were distributed uniformly throughout the 24hr cycle. Detections were not found to differ significantly from a uniform distribution with no mean resultant time (Rayleigh test: p > 0.05, r= 0.004, n= 10827). Similarly, missed transmissions did not differ significantly from a uniform distribution with no mean resultant time (Rayleigh test: p >

0.05, r = 0.0002, n= 224447). No evidence of a diel pattern was found in the hourly distribution of successful detections or missed transmissions over the 47 day study.

3.3.4 Detection Range

Daily proportions of detected transmissions were found to decrease with increasing tag–to-receiver spacing in all four tag models examined (Figure 3-10).

However, daily proportions of expected transmissions logged were found to be highly variable, ranging by as much as 0.3-0.5 between peak and minimum daily efficiency at each test distance. In general, high power tag models (V16 and V13) had different detection profiles than those of the lower power tags (V7 and V9) (Figure 3-10). Very few transmissions from each tag model were detected at the maximum tag to receiver

70 spacing tested; these distances were 813m for V16 and V13 models, and 507m for V9 and V7 models. A minimum working detection efficiency, assumed to be 50% (Kessel et al., 2014), was achieved at approximate distances of 300m, 200m, 150m, and <100m for

V16, V13, V9, and V7 tag models, respectively (Figure 3-10).

3.3.5 Model of Acoustic Detection Efficiency with Current Speed

In general, the probability of detection was significantly correlated with tag power, tag-to-receiver distance, tidal direction, and current speed. The most parsimonious model with the best fit to the data was the maximal model which described detection probability as a function of all four explanatory parameters and their interactions (Table 3-5; GoF likelihood ratio test: G = 78412, df = 31, p < 0.001).

Current speed was found to be an important predictor of the probability of detection; however, this relationship varied with tag model, distance, and tidal direction

(Figures 3-11 through 3-14). Predicted probability of detection decreased rapidly with increasing current speed during both tidal stages. Distinct differences in detection efficiency were predicted between ebb and flood tidal stages at lower current speeds; however, these differences were often predicted to converge with increased current speed and particularly in higher power (V13 and V16) tag models. Figure 3-15 clearly indicates this pattern across transmitter models and distances. An irregular relationship between the probability of detection and current speed was also evident at an approximate detection distance of 1m (co-located tag and receiver), where the probability of detection was positively correlated with current speed for the three

71 highest power tag models (V16, V13, and V9), but showed no relationship for the lowest powered tag model (V7) as its detection efficiency remained consistent under all current speeds (Figure 3-15).

A diel (24hr) modelled probability of detection combined with actual detection records is shown in relation to current speed for the V16 tag model at intermediate distance of 290m from the receiver (Figure 3-16). Two patterns are clearly evident: 1) peaks in detection probability occurred during periods of reduced current speed (slack periods), and 2) the probability of detection is higher for a longer duration during the low water slack period compared to high water slack.

3.4 DISCUSSION

This study presents the first directed, long term, detection efficiency and range test of VEMCO acoustic telemetry equipment within a high current hyper-tidal environment. Development of a sub-surface mooring design, which successfully withstood a deployment of more than 1.5 months with a high rate of recovery, was an important achievement. Positioning the instruments sub-surface and just above the seabed prevented interaction with vessel traffic, reduced risk of entanglement with floating debris, and situated instrumentation in lower overall current speeds. While one mooring station was not recovered initially, the eventual failure of its galvanized steel riser chain through corrosion and chaffing permitted its later recovery. Inspection of the acoustic release mechanism indicated that an o-ring seal had failed leading to a leak which disabled the release. While not planned as a test in this study, it was found that

72 use of mooring components which eventually wear/corrode can act as a failsafe in cases of acoustic release failure. This is particularly relevant in high current areas, such as

Minas Passage, where recovery by methods including divers, dragging/grappling, or by

ROV’s may not be possible.

This study also constituted one the first applications of the VEMCO Positioning

System (VPS) within a high current speed environment. Given the array design utilized, the VPS technique was not successful in determining precise distances between moored receivers. Simultaneous detections of individual transmitter signals did not occur with enough consistency to accurately determine between mooring spacing, with the exception of stations 5 and 6, where an estimate was found to be in close agreement with the distances calculated from surface GPS positions. To increase success of the VPS technique, receiver stations would need to be located in very dense arrays (<100m spacing). The equipment investment required, limitations to coverage area, and continued uncertainty regarding the effectiveness of the VPS technique in extreme high flows, may preclude its use to track the movement of animals in future studies within

Minas Passage and in similar high flow environments.

Telemetry range and efficiency testing studies assume that individual transmitters (same model and coding specifications) have equal chance of being detected, and that all receivers are equally efficient at decoding the signals (Clements et al., 2005). However, this may not be the case, as individual variability in both tags and receivers have been reported (Melenychuk, 2012b). Had sufficient equipment been accessible, the value of this study could have been improved by including replication at

73 the level of both receiver and tag. Variation in tag output power by even a fraction of a decibel (dB) or slight differences in receiver sensitivity could have significant implications for tag signal propagation as well as the detection performance of the receiver. It could also greatly complicate the task of determining the detection efficiency of arrays of receivers used to establish acoustic “gates”. This study was temporally comprehensive and highlighted a considerable degree of variation in detection efficiency over time by identical receivers, serving to emphasize the importance of conducting long term range testing studies to properly categorize environmental variability. The use of multiple replicate receivers and test tags in future range testing studies would help to further distinguish variability in equipment performance from variability induced by the environment.

Another important component of this study was the examination of four models of tags with different power output. As battery life and output power level are constrained by tag size, and no one tag model can be applied to all species or life stage, tradeoffs are often required in selecting a tag model (Heupel et al., 2006). Kessel et al.

(2014) highlighted that studies expecting to use multiple tag models should incorporate all tag types into range and efficiency testing. Our results support this recommendation in that distinct detection efficiency curves were observed for each tag model. Some studies have used a single tag model for range and efficiency testing, and then assumed similar detection efficiency curves for other models, or pro-rated results based on output power (dB) (see review in Kessel et al., 2014). Our results indicate that these may be oversimplistic approaches, particularly when applied to complex environments.

Further, our study has highlighted that certain tag models may not be appropriate in some environments. For example, in the present study the range of the V7 model was greatly limited and may preclude its future use in Minas Passage.

The deployment and short term operation of the OpenHydro in-stream turbine did not appear to impact receiver detection and efficiency. Comparisons of pre- vs post- installation conditions indicated a significant difference in some performance metrics, at some receiver stations but no pattern was evident in these results to clearly indicate an impact of turbine operation on array performance. Receiver stations 6 and 5 were situated in closest proximity to the turbine, within 119 and 149m, respectively. For these stations, there was no significant difference in any metric between pre- and post- turbine operation periods.

The cde metric indicated that less than half of all transmitted signals were successfully detected in this study, similar to results obtained in complex estuarine

(Simpfendorfer et al., 2008) and coral reef environments (Welch et al., 2012). As reported in numerous other studies, detection efficiency was found to decrease with increasing tag-to-receiver distance (reviewed by Kessel et al., 2014), however daily efficiency was variable at each test distance. There was no indication of diel patterns in either detected or missed transmissions, similar to results shown in other study sites dominated by tidal currents (Mathies et al., 2014). Diel differences in detection efficiency have been linked to increased biological activity and daily weather events

(Heupel et al., 2006; Hobday and Pincock, 2012). However, the dominant influence of tidal currents within Minas Passage was clearly evidenced by peaks in detection during

75 periods of reduced current speed (around slack tide), while distinct periods of reduced to no detection were found during periods of high current speeds for all tag models.

Currents and wave driven circulation have been identified as important factors influencing detection efficiency and transmission range in acoustic telemetry studies

(Clements et al., 2005; Simpfendorfer et al., 2008; How and Lestang, 2012; Gjelland and

Hedger, 2013; Mathies et al., 2014). Not surprisingly, the extreme current speeds present in Minas Passage were found to contribute greatly to the variability in detection efficiency. However, the specific mechanism(s) by which increased current speed impacts detection performance could not be identified directly. Several potentially contributing mechanisms are suspected.

Tidal currents increase ambient noise levels in Minas Passage through entrainment of air bubbles (Melvin and Cochrane, 2014), shifting bottom substrate

(Fader, 2009), production of turbulent flow and eddies, and suspension of sediment and debris (Martin et al., 2012; Porskamp, 2013). These factors combine to reduce detection efficiency and limit potential transmission range through both scattering/damping of the propagating acoustic signal (Pincock and Johnston, 2012) and production of interfering noise which can generate false pulses or lower the signal to noise ratio thus masking acoustic signals at the receiver (Clark et al., 2009; Welch et al., 2012).

Further, tidal currents may significantly alter the orientation of moorings influencing the relative positions of the receiver(s) and tag(s). For example, the receiver positioned at Station 1 experienced two periods of unexpected detection activity, which were removed from all subsequent analysis. This receiver was returned to the

76 manufacturer for inspection; it was determined that the periods of unexpected activity were most likely attributed to the acoustic receiver sliding up the mooring cable and periodically contacting the range testing tags (D. Webber, VEMCO, pers. comm.). During recovery it was noted that the station 1 receiver had become loose and was able to slide up the riser cable, lending support to this theory.

The orientation of acoustic telemetry receivers has also been shown to impact detection efficiency (Clements et al., 2005; Titzler et al., 2010). Clements et al. (2005) indicated that mooring assemblies exposed to 2 m/s currents in the Columbia River tilted by up to 45° from vertical. The SUBS floatation package used in the present study has been shown to maintain horizontal orientation in currents up to 5m/s (D. Wellwood,

Open Seas Instrumentation, pers. comm.), however, the riser assembly to which the receiver and tags were attached would be expected to deviate considerably from vertical during both ebb and flood tidal stages. Such deviation would likely position the

SUBS flotation at some stations in the direct line of sight between the tag and downstream receivers, or situate tags and receivers in closer proximity to bathymetric features which could potentially block signals. Moorings may also generate vibrational noise through strumming and movement of metal hardware (i.e. chain, shackles, etc.) that may interfere with acoustic transmissions or contribute to background noise levels.

The use of tilt sensors could help to determine mooring and/or receiver orientation during tidal flow, and permit evaluation of the impacts of position on detection efficiency during future studies.

The hard bottom substrate present within the FORCE site has the potential to reflect acoustic signals (echoes), but the potential for echo generation may have also been enhanced by use of air filled floatation. Signal echoes can interfere with decoding of the original transmission. The receiver may interpret an echo as either extra pulses or as alterations of the inter-pulse interval (code spacing). This can be particularly troubling at short range, where echo conditions can limit detection efficiency. This counterintuitive phenomenon, termed the “donut shadow effect” (D. Webber, VEMCO, pers. comm.), was observed for tags (V9, V13, and V16) co-located with receivers (tag to receiver distance of ~1m). There was no effect of co-location on detection efficiency for the V7 tag model. Interestingly, the “donut shadow effect” on V9-V16 models decreased as current speed increased. This improvement in detection with increasing current speed may have resulted from increased background noise levels, lowering the signal to noise ratio, therefore masking the echoed signals from detection. These results highlight that high output power tag models may generate strong echoes during fixed deployment range testing, which may significantly impact the performance of co- located receivers. Echoes may also impact receivers at greater distance, and should be considered carefully, particularly in quieter acoustic environments where echoes may propagate further.

Considering the potential echo producing situation described above, rejected transmissions were not deemed a significant issue for this study, and were found to be similar to results reported in less acoustically noisy environments (Simpfendorfer et al.,

2008; Welch et al., 2012). Rejected transmissions are generally expected in studies using

78 a large number of tags within range of the receiver. In these circumstances, a high number of rejected transmissions is indicative of a high number of signal collisions

(Simpfendorfer et al., 2008). In this study several measures were taken to prevent signal collisions, including: limiting the number of viable tags (9), programming all tags with long delays (8-10mins), and manually offsetting start times of fixed delay range test tags.

The daily noise quotient metric (nq) was found to be consistently negative at all receiver stations, which is reportedly indicative of the presence of many tags within the range of a receiver, which also increases the potential for signal collisions

(Simpfendorfer et al., 2008). Conversely, large positive values of the noise quotient result if high levels of impulsive environmental noise were produced within the frequency range of a receiver, thus generating false pulses.

Given that collisions were not deemed to be a significant factor in this study, as evidenced by low rc values, the subsequent interpretation of negative nq values does not provide evidence to indicate that receivers detected impulsive environmental noise as signals, but rather were impacted by continuous interfering environmental noise

(Welch et al., 2012). Where continuous environmental background noise is present, the signal to noise ratio is reduced, thereby elevating the detection threshold of the receiver, resulting in lower detection range and missed pulses leading to lower overall detection efficiency (Ehrenberg and Steig, 2009; Welch et al., 2012). All tags deployed in this study consisted of an 8 ping transmission sequence. If all 8 pulses of an individual transmission were detected, but the code sequence was interrupted by pulses from

79 other tags within the detection range or by intermittent environmental noise at a similar frequency, the original transmission would be rejected as a checksum error. Invalid checksum rejections only occur if a full code sequence is received. If the rejection coefficient is low, indicating that rejection of fully detected transmissions due to invalid checksums were uncommon, it is likely that low overall code detection efficiency was a result of incomplete code sequences. This may be attributed to signal blockage due to moorings and bathymetry, and/or high levels of continuous environmental noise.

The detection efficiency model predicted that both current speed and tidal stage

(flood or ebb) were significant factors in detection performance. Ebb and flood tides are asymmetrical with respect to current velocity in Minas Passage (Karsten, 2008). Flood currents are generally faster and more turbulent than ebb tides which are more uniform and laminar. In all tag models, predicted detection probabilities were different between ebb and flood, where probability of detection during ebb tide was greater than flood tide. Even more interesting is that these differences converged with increasing tidal current speed, and in some cases reversed at the highest speeds. Melnychuk (2012a) highlights turbulence as a severe issue when flow shifts from smooth (laminar) to turbulent. While turbulence is difficult to measure, riverine studies have indicated that turbulence can produce abrupt changes in tag detection distance from 100m to less than 10m (Melnychuk, 2012a). Although not measured in this study, it is suspected that turbulence, particularly during flooding tide, impacted upon performance results.

Further, as the deployment design used in this study placed low and high power tag models on opposite ends of the array, the use of tag power as a factor in the

80 detection efficiency model required the assumption that position of the tag within the array had no effect on detection efficiency. This, however, may not be the case as the phenomenon of Doppler shifts may impact transmitted signals differently depending upon direction of the current (Mathias et al., 2014). Transmissions travelling toward a receiver with the current flow would experience an increase in pulse frequency and therefore a slight decrease in inter-pulse intervals. Conversely, transmissions travelling toward a receiver against the current flow would experience a decrease in pulse frequency, and therefore a slight increase in inter-pulse intervals (Mathias et al., 2014).

Changes to the in inter-pulse interval can impact how the acoustic receiver identifies and decodes the transmission, and may result in reduced detection efficiency. It is possible that the unexpected result may be attributed to some combination of the factors identified above, likely in concert with artefacts of array or mooring design.

A limitation of this study was that it used model output of tidal elevation and current speed, and did not directly measure these variables during the study. A single temperature and depth sensor was attached to the acoustic release at station 3; however, this sensor was never recovered. Despite confidence in the representative nature of the tidal models, which have been validated by ADCP measurements within the FORCE test site, tidal current speed values used here were depth-averaged. As we elected to position all tags and receivers near the bottom where currents are probably slower than average values, a potential bias was introduced; this may be problematic for the interpretation of detection efficiency for studies of electronically tagged pelagic animals moving higher in the water column. Given that tidal current speeds are greater

81 near the surface, and that performance-reducing impacts due to air entrainment, turbulence, and weather are also greater at the surface, detection efficiency of transmissions emitted in surface waters may be further reduced.

Interpretation of results could have been enhanced by the acquisition of baseline soundscape data with which the level of interfering noise generated by tidal currents could be quantified and used to further define the probability of detecting a transmission. Broadband hydrophones have been used to evaluate background noise in other acoustic telemetry studies (Heupel et al., 2006; Melnychuk, 2012a). It is recommended that hydrophone measurements be conducted concurrently with any future range and efficiency testing.

Given the narrow frequency range over which the VEMCO VR2w (69kHz) receiver detects acoustic energy, it is important to evaluate whether interfering sound exists at the specific frequency of the tags or if broadband noise is being generated at high current speeds and simply masks the target frequency of the acoustic transmitters. At the time this study was conducted, limited background information was available to classify the ambient noise profile of Minas Passage. However, this area has been receiving more attention including recent studies (Martin et al., 2012; Porskamp, 2013) that may be useful in examining how acoustic properties of the system change with tidal stage, tidal cycle, and current speed. Additionally the detection efficiency model did not incorporate weather data such as precipitation, wind, or sea state. These factors have been identified as having significant impact on detection efficiency in studies at sites less extreme than Minas Passage (Heupel et al., 2006; Kessel et al., 2014). While it is

82 expected that the influence of tidal conditions likely far exceeds the impacts of such factors within Minas Passage, this assumption should be tested and confirmed.

3.4.1 Conclusions and Recommendations

This study has demonstrated the potential of VEMCO acoustic tracking technology for use in Minas Passage. Detection of all tag models was negatively influenced by tidal currents, thus limiting detection range and overall efficiency. In general, higher power tag models achieved better overall detection efficiency and transmission range. Detection efficiency was found to decrease to near zero during peak current flow periods, and was highest during periods of reduced current speed near slack water. There was no indication that the installation and operation of the

OpenHydro TISEC device at the FORCE test site impacted negatively on study results. A detection efficiency model indicated that the maximal model, including all factors

(current speed, tidal direction, tag power, and distance) and their interactions, was the best fit of the data. The model predicted distinct differences in detection efficiency between ebb and flood tidal stages. Assessment of these effects is necessary to improve array design, cost effectiveness, and to ensure the best possible data collection in future deployments of acoustic receiver arrays within Minas Passage.

Results from this study are expected to be relevant for other high current sites; many of which are also being considered for TISEC device development and testing. In high flow areas, animal tracking studies should use the highest output power transmitter that can be carried by the study species, and receiver arrays should be positioned as densely as equipment resources permit. To further reduce missed

83 detections during animal tracking studies in high current environments, receivers should be deployed in overlapping and offset parallel gates, as suggested by Clements et al.

(2005). To gather additional information on processes which may impact detection efficiency, concurrent collection of environmental and physical data is advised. This may include ADCP current profilers, broadband hydrophones for background soundscape data, tilt loggers, and depth sensors to examine mooring orientation, as well as temperature and salinity loggers that can help characterize the expected sound propagation potential.

Given the extreme tidal conditions present within Minas Passage, direct exposure of instrumentation to the elements should be avoided. The VR2w receiver transducer is most sensitive when positioned vertically, with the caveat that it is least sensitive to detecting tags positioned in planes directly above or directly below the receiver (Clements et al., 2005; Melnychuk, 2012a; Pincock and Johnston, 2012). Future studies should consider mounting instruments within the SUBS floatation to offer protection, limit instrument movement, and maintain the vertical position of the receiver during high flow conditions. Reducing riser lengths would help keep instrumentation in the lowest current speed possible. Additionally, it may be advantageous to utilize floatation which is not air filled, such as syntactic foam or other alternatives, to help prevent echoes.

Subsequent studies of animal movement in Minas Passage should be performed with care and caution, and incorporate range and detection efficiency testing results to inform receiver array design and aid the interpretation of movement data collected

84 from tagged animals. Lastly, users of acoustic technology should be cautious that absence of detections is not necessarily evidence of absence of a tagged animal.

3.5 TABLES

Table 3-1. Instrument deployment and recovery metadata for 7 VEMCO VR2w acoustic receiver mooring stations positioned at the FORCE test site within Minas Passage, NS.

Station Latitude Longitude Deployment Recovery Clock Drift (W -> E) (dd.ddddd) (dd.ddddd) Date Date (m:ss)

1 45.36482 -64.43274 10/9/2009 11/26/2009 -0:45 2 45.36459 -64.43067 10/9/2009 11/26/2009 -1:20 3 45.36418 -64.42917 10/9/2009 7/16/2011* 8:11 4 45.36422 -64.42883 10/9/2009 11/26/2009 -1:05 5 45.36393 -64.42751 10/9/2009 12/3/2009 -1:34 6 45.36388 -64.42641 10/9/2009 11/26/2009 -1:33 7 45.36284 -64.42276 10/9/2009 11/26/2009 -0:12 (*) – indicates lost station, recovered at later date.

Table 3-2. Model specifications for each of 4 VEMCO acoustic tags acoustic receiver mooring stations positioned at the FORCE test site within Minas Passage, NS.

Station Tag Dimensions Output Power Frequency Delay (sec) Est. Battery Model (L x D, mm) (dB re 1μPa @ (kHz) Life (days) 1m) 1 V16-5H 95 x 16 165 69 480, fixed 2046 1 V13-1H 36 x 13 153 69 480, fixed 556 6 V9-2H 29 x 9 147 69 480, fixed 321 6 V7-4L 22.5 x 7 136 69 480, fixed 114

Table 3-3. Receiver detection parameters and mean daily performance metrics for each of 7 moored VEMCO VR2w acoustic receiver stations over 47 days of continuous monitoring. Detection parameter data incorporates a total of 9 tags deployed within the system (4 range tags (Table 3-2), and 5 sync tags). Note that two periods of spurious activity at Receiver Station 1 were removed (see text for explanation).

Station Days Detects Pings Syncs Rejec cde rc nq (W - E) Logged (D) (P) (S) ts (Ẋ ± SD) (Ẋ ± SD) (Ẋ ± SD) (C) 1 29* 13136 177023 32723 430 0.408 0.013 -2922.7 (0.066) (0.003) (938.2) 2 47 21759 299186 50799 2253 0.436 0.044 -2280.9 (0.063) (0.007) (866.3) 3 47 27386 351869 64645 1911 0.375 0.030 -3516.8 (0.065) (0.008) (1172.3) 4 47 25254 367785 68436 1625 0.376 0.024 -3823.4 (0.053) (0.006) (1092.4) 5 47 23134 356821 64680 2665 0.360 0.041 -3417.4 (0.043) (0.007) (818.1) 6 47 29347 385918 62438 1802 0.468 0.028 -2723.1 (0.081) (0.004) (989.7) 7 47 11291 197573 33628 927 0.339 0.027 -1520.2 (0.044) (0.008) (445.4)

Table 3-4. Summary of Kruskal-Wallis tests performed to compare code detection efficiency (cde), rejection coefficient (rc), and noise quotient (nq) pre- and post-installation of the OpenHydro TISEC device in Minas Passage. Detection parameter data incorporates a total of 9 tags deployed within the study system (4 range tags (Table 3-2), and 5 sync tags). Note that periods of spurious activity at Receiver Station 1 were removed.

Statio Estimated Total Total Days Days P-Value P-Value P-Value n Distance Days Detects Logged Logged cde rc nq from Logged (D) Pre Post Turbine Install Install (m) 1 506 29 13136 28 1 NA NA NA

2 346 47 21759 33 14 0.027 * 0.184 0.0004 *

3 242 47 27386 33 14 0.028 * 0.011 * 0.011 *

4 216 47 25254 33 14 0.204 0.953 0.048 *

5 149 47 23134 33 14 0.152 0.358 0.217

6 119 47 29347 33 14 0.780 0.408 0.295

7 361 47 11291 33 14 0.364 0.007 * 0.852

Note: (*) – indicates a significant difference between pre- and post-installation.

Table 3-5. Akaike’s second-order information criterion (AICc) of logistic regression models of range test tag detection probability (Detection) in Minas Passage, Bay of Fundy (BoF).

Model Formulation K AICc Delta AICc Cum. LL Mod AICc Wt Wt el

m1 Detection ~ Tag * Tide * Distance * Speed 112 198361.9 0 1 1 -99068.9

m5 Detection ~ Tag * Distance * Speed 56 199723.2 1361.34 0 1 -99805.6

m2 Detection ~ Tag * Tide * Distance 56 211452.5 13090.63 0 1 -105670

m6 Detection ~ Tag * Distance 28 212239.9 13878.06 0 1 -106091

m8 Detection ~ Tide * Distance * Speed 28 218972.9 20611.03 0 1 -109458

m15 Detection ~ Tag + Tide + Distance + Speed 12 219331.3 20969.44 0 1 -109653

m18 Detection ~ Tag + Distance + Speed 11 219598.5 21236.61 0 1 -109788

m21 Detection ~ Tide + Distance + Speed 9 224732.9 26371.01 0 1 -112357

m16 Detection ~ Tag + Tide + Distance 11 225954.7 27592.82 0 1 -112966

m19 Detection ~ Tag + Distance 10 226150.2 27788.33 0 1 -113065

m9 Detection ~ Tide * Distance 14 231036.4 32674.57 0 1 -115504

m22 Detection ~ Tide + Distance 8 231197.5 32835.62 0 1 -115590

m11 Detection ~ Distance 7 231387.8 33025.96 0 1 -115686

m3 Detection ~ Tag * Tide * Speed 16 275157.2 76795.34 0 1 -137562

m7 Detection ~ Tag * Speed 8 275680.8 77318.92 0 1 -137832

m17 Detection ~ Tag + Tide + Speed 6 275753.8 77391.99 0 1 -137870

m20 Detection ~ Tag + Speed 5 275978.6 77616.71 0 1 -137984

m10 Detection ~ Tide * Speed 4 279890.2 81528.29 0 1 -139941

m23 Detection ~ Tide + Speed 3 279923.9 81561.99 0 1 -139958

m12 Detection ~ Speed 2 280143.8 81781.92 0 1 -140069

m4 Detection ~ Tag * Tide 8 280810.6 82448.78 0 1 -140397

m24 Detection ~ Tag + Tide 5 281094.6 82732.75 0 1 -140542

m13 Detection ~ Tag 4 281232.5 82870.66 0 1 -140612

m14 Detection ~ Tide 2 285172.9 86811.02 0 1 -142584

Note: The number of parameters (K), AICc, AICc differences (Delta AICc), Akaike weights (AICcWt), cumulative AICc weights (Cum.Wt) and log-likelihood (LL) are listed for each candidate model (gi). Model covariates and categorical variables are Tag (4 levels: V7, V9, V13, V16), Tide (2 levels: Ebb and Flood), Distance (Discrete distance between the sentinel tag and receiver, m) and, Speed (Continuous estimates of current speeds, m·s -1).

3.6 FIGURES

Figure 3-1. Upper Bay of Fundy inset within a map of the Maritimes. The Minas Passage is the 6 km wide passage between Minas Basin and Minas Channel and is home to the Fundy Ocean Research Centre for Energy (FORCE) Tidal In-Stream Energy Conversion (TISEC) device test site (indicated by red rectangle). Figure prepared by S. Oldford-McLellan.

Figure 3-2. Predicted flow speeds (m/s) and direction in the Minas Passage during a typical flood tide (top) and a typical ebb tide (bottom). The arrows indicate the direction of the flow at the given location. The white box is the FORCE lease area. Figures prepared by Dr. Richard Karsten, Acadia University.

Figure 3-3. Orientation of mooring components, Left: A) SUBS streamlined instrument buoy, B) 5/16” pvc jacketed stainless steel riser cable, C) VEMCO VR2w acoustic receiver, D) Teledyne-Benthos 875-TD acoustic release mechanism, E) 3/8” galvanized steel chain riser, F) ~200kg steel moorings weight. Right: S. Kirchhoff (OTN) with a 5m mooring assembly hoisted over the stern of the vessel prior to deployment on October 9, 2009.

Figure 3-4. Positions of 7 VEMCO VR2w acoustic receiver mooring stations (numbered open circles) deployed within Minas Passage, NS at the FORCE TISEC test site (black rectangle) during fall 2009. The OpenHydro TISEC device (square with lightning bolt emblem) was deployed on November 12, 2009. 10m bathymetric contours are indicated.

Figure 3-5. Code detection efficiency (cde) metric values (black dotted line) and tidal range (gray dashed line) throughout the study for receiver Stations 1-7 from top to bottom respectively. The vertical grey line at Julian Day 316 indicates the deployment date of the OpenHydro TISEC device.

Figure 3-6. Daily rejection coefficient (rc) metric values (black dotted line) and tidal range (gray dashed line) throughout the study for receiver Stations 1-7 from top to bottom respectively. The vertical grey line at Julian Day 316 indicates the deployment date of the OpenHydro TISEC device.

Figure 3-7. Daily noise quotient (nq) metric values (black dotted line) and tidal range (gray dashed line) throughout the study for receiver Stations 1-7 from top to bottom respectively. The vertical grey line at Julian Day 316 indicates the deployment date of the OpenHydro TISEC device.

Figure 3-8. Paired boxplots of daily performance metrics indicated by receiver station. Pre-turbine deployment conditions are indicated by grey boxes, while post-turbine deployment conditions are indicated by white boxes. Stations 2 through 7 indicate 33 and 14 days, while Station 1 indicates 28 and 1 day of pre- vs. post- turbine data, respectively.

Figure 3-9. Distribution of detected (top) and missed (bottom) transmissions binned by hour of day in which they were expected. Data is pooled for all tag models (4) and receivers (7) over the 47 day monitoring period. Detected and missed transmissions binned by hour of the day were not found to deviate significantly from a uniform distribution (Rayleigh tests – Detected: P > 0.05, r = 0.004, n = 10825, Missed: P >0.05, r = 0.002, n = 224447). Note that the y-axis scale differs between top and bottom panels.

Figure 3-10. Daily proportion of expected transmissions logged successfully by each receiver station. Range test tags featured fixed delays (480 sec) were manually offset by 120 s to avoid signal collision. Number of expected transmissions/day = 180. Note that x-axis scale differs between top and bottom panels.

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Figure 3-15. Plots of estimated (solid line) effect of current velocity (m/s) on detection probability during ebb (black) and flood (red) tide at varying distance between sentinel tags (V7, V9, V11, V16) and receivers. 95% confidence intervals denoted by dashed lines. All tags included distances of 0m and 507m, V9 and V7 tags also included 194m and 308m while V13 and V16 tags included distances of 165m and 313m. Note the detection probability of V16, V13, and V9 tag models increased with increasing current speed at co- located positions (~1m tag to receiver distance).

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Figure 3-16. Example of the predicted probability (solid line) and 95% confidence intervals (dashed lines) produced by the most parsimonious model for October 17, 2009. Also shown are the actual transmissions (circles) where those at 0 and 1 represent missed and detected transmissions, respectively. Estimated depth-averaged current speed is shown along the top (dark dashed-dotted line). A flooding tidal stage is denoted by grey shading.

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CHAPTER 4 - Detection of acoustically tagged Striped Bass across Minas Passage and within the FORCE test area

4.1 INTRODUCTION

Migratory patterns of Striped Bass have been studied broadly since the 1930’s using conventional mark-recapture tagging methods, with studies indicating considerable variability in the degree and extent of migration of stocks across the species range (Merriman, 1941; Raney, 1952; 1954; Chapoton and Sykes, 1961; Clarke,

1968; Kohlenstein, 1981; Boreman and Lewis, 1987; Dadswell and Rulifson, 1995).

The Shubenacadie River (SR) system supports the last remaining Striped Bass spawning stock within the Bay of Fundy (BoF) population (COSEWIC, 2012). Genetic assessment of historic samples indicates that the occurrence of SR origin Striped Bass has ranged throughout the BoF, with a distribution that has extended to the Gulf of

Maine (including the Saint John River, NB) and along the southern Atlantic coast of Nova

Scotia (Bradford et al., 2012; DFO, 2014). Mixing of Bay of Fundy and US Striped Bass stocks has been observed. Striped Bass tagged in the Minas Basin demonstrated migration to US waters (Rulifson and Dadswell, 1995; Rulifson et al., 2008). And bass tagged in the US have been recaptured in the Minas Basin (Dadswell and Rulifson,

1995).

It is likely that some proportion of SR origin Striped Bass, in addition to suspected US migrants, utilize the Minas Passage as a migratory pathway to/from the

Minas Basin and outer BoF. However, the timing and extent of such movements and the fraction of the population of Striped Bass of different origins occupying Minas Passage

103 has not been able to be determined through use of conventional mark-recapture tagging methods (see Chapter 2).

Advances in bio-telemetry technology have given rise to powerful tracking tools that can be used to collect information regarding fish presence/absence, movement/migration, activity, behavior, and habitat use that would not be possible by other means (Cooke et al., 2004; Heupel et al., 2006). With specific reference to Striped

Bass, the advancement of electronic tagging and tracking methods has permitted enhanced resolution of migration patterns and habitat use that were not discernable through conventional tagging approaches (Able and Grothues, 2007; Ng et al., 2007;

Douglas et al., 2009; Graves et al., 2009; Mather et al., 2009; Mather et al., 2010;

Pautzke et al., 2010; Wingate et al., 2011; Able et al., 2012; Kneebone et al., 2014).

Striped Bass entering or exiting Minas Basin must travel through Minas Passage, one of the preeminent tidal energy sites in the world (EPRI, 2006; Karsten et al. 2008). In

2009, the Fundy Ocean Research Centre for Energy (FORCE) was established within

Minas Passage as a site for tidal in-stream energy conversion (TISEC) device demonstration. Deployment and testing of in-stream tidal turbines within Minas

Passage presents a potential risk to Striped Bass and other fish that utilize Minas

Passage for migration or for other purposes such as feeding. Habitat use within Minas

Passage has not been well resolved from past mark-recapture studies of Striped Bass tagged from the Minas Basin and SR system, generally because of the lack of intercepting fisheries in this area (Bradford et al., 2012; Chapter 2 – this study). Bridging

104 the knowledge gap of Striped Bass marine activity within the Bay of Fundy is now a high priority due to testing of in-stream tidal turbines within Minas Passage as well as conservation concerns assessed by the species by the Committee on the Status of

Endangered Wildlife in Canada (COSEWIC) which has recommended that the Bay of

Fundy population be considered for Endangered designation (COSEWIC, 2012; DFO,

2014).

In this study, VEMCO acoustic telemetry technology was used to document

Striped Bass presence and depth preferences within Minas Passage, NS and the FORCE

TISEC demonstration area. Objectives were to: 1) characterize Striped Bass occupancy within Minas Passage, 2) examine Striped Bass presence within the FORCE demonstration area, and 3) determine swimming depth preferences. This information is essential to addressing questions related to potential impacts of tidal energy in-stream turbines on Striped Bass moving through and within the Minas Passage.

4.2 METHODS

4.2.1 Study Area

This study was conducted within Minas Passage, Bay of Fundy, Nova Scotia.

Minas Passage is a 6 km wide, and up to 160m deep, constriction that separates Minas

Channel from Minas Basin (Figure 3-1). The hyper-tidal range (7-13m) within Minas

Passage is generated through a combined effect of the funnel shape of the Bay of Fundy in concert with the natural tidal resonance period of the Bay of Fundy–Gulf of Maine system which is slightly larger than the 12.42 hour period of the dominant semi-diurnal lunar tide (Garrett et al., 1972; Karsten et al., 2008). Tidal forcing through Minas Passage

105 generates powerful flow which can reach 106 m 3/s during tidal exchange, with sustained depth-averaged tidal currents of up to 3.28m/s (Figure 3-2, Karsten et al., 2008). Surface currents can reach velocities of 6m/s during spring tides (Oceans Ltd., 2009), however, speed decreases considerably with depth. Tidal flushing and turbulence within the system causes strong vertical mixing which prevents temperature and salinity stratification (Envirosphere, 2009). The bathymetry of Minas Passage is highly variable.

The greatest depths are found in the highly scoured central and southern regions of the passage.

The FORCE site is located in the northern portion of Minas Passage and consists of a 1.6 x 1.0 km area of Crown Leased seabed, with depths of approximately 30-55m at mean water level (MWL) (Fader, 2009; Envirosphere, 2009). On November 12 th , 2009, an OpenHydro TISEC turbine (ducted, 10m diameter, 12 blades) was deployed on a 400 tonne tripod gravity base within the FORCE demonstration area. The turbine remained in place for over a year, but was for only operational (i.e. blades turning) for the first three weeks of its deployment (FORCE, 2011). It was later determined that this operational period did not overlap with the tracking study.

4.2.2 Passive Monitoring of Fish Movements

The acoustic telemetry system used in this study consisted of receivers and transmitters manufactured by VEMCO (Halifax, NS, www.vemco.com). The VEMCO

VR2w hydro-acoustic receiver is a passive, omnidirectional, single channel (69kHz), hydrophone that functions to autonomously detect, time stamp, and store coded signals emitted by acoustic transmitters (tags). Acoustic transmitters are generally attached to

106 fish and other aquatic animals, most often by surgical implantation or external attachment (Heupel et al., 2006). Tags emit unique coded ping sequences which are decoded by acoustic receivers to identify the specific carrier animal, the date and time of detection, and any sensor data (i.e. depth, temperature, acceleration) if tags are equipped to provide this information.

4.2.3 Striped Bass Collection and Tagging

During 2010, a total of 80 Striped Bass were captured by angling and surgically implanted with VEMCO V13P-1H pressure sensing acoustic transmitters (69kHz, 153dB re 1μPa @ 1m, 36mm x 11mm, Randomized Delay: 45-95sec, Battery Life: 214 or 170 days). All Striped Bass were captured through shore-based angling from two sampling locations (Figure 4-1). One of these sites was located on the Stewiacke River, NS

(described extensively by Rulifson and Tull, 1999 and MacInnis, 2012), approximately 6.5 km upstream from the confluence with the Shubenacadie River near known Striped Bass spawning grounds (Dadswell and Rulifson, 1995; Bradford et al., 2012). A total of 43 adult Striped Bass were angled and tagged at this site during May 10-13, 2010 (Table 4-

1; Appendix 4-A). The second site was located near Grand Pré, NS in the Southern Bight of Minas Basin, NS, at a common recreational angling location known as “The Guzzle”

(described in Chapter 2). A total of 37 Striped Bass were angled and tagged at this location during August 4-16, 2010 (Table 4-1, Appendix 4-A).

Methodology for surgical implantation of transmitters followed Douglas et al.

(2009). Striped Bass were anesthetized using a 10% by volume Eugenol (clove oil)

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(Hilltech, Vanleek Hill, ONT) in ethanol (95% EtOH) solution. Clove oil, an effective anesthetic for reducing short-term stress response related to handling and surgeries, was used in this study as it has faster anesthetization induction and recovery times compared to MS-222 as well as shorter residency times within the fish (Cooke et al.

2004; Kildea et al. 2004). The Eugenol/Ethanol mixture was added to ambient temperature water from the tagging site to produce a 40mg/L anesthesia bath.

Fish deemed suitable for surgery were placed immediately after capture into the anesthesia solution and were monitored for induction of Stage II anesthesia: loss of equilibrium, no reaction to external stimuli, and regular but decreased opercular rate

(Iwama et al., 1989; Iwama and Ackerman, 1994). Anesthetized bass were then transferred to a wet surfaced measuring board where fork and total lengths were recorded. A 3” T-Bar style spaghetti tag (Floy Tag, Seattle, USA) was inserted at the base of the spinous dorsal fin. A sample of 6-10 scales was removed from an area below the spinous dorsal fin but above the lateral line and stored in paper envelopes. Lastly, a small clip of tissue from the pectoral fin was collected for genetic analysis and placed in a vial containing 95% ethanol.

Following these procedures the bass was positioned ventral surface facing up, in a wet surfaced surgical trough, permitting the gills to remain under water but with the surgical area exposed. The surgical area, approximately 30mm x 30mm, was disinfected with Aqueous 2% Stanhexidine 4% Ethanol topical disinfectant solution (Omega

Laboratories, Montreal, Quebec). An area of scales (10mm x 30mm) was removed from around the incision site, the area was re-irrigated with Stanhexidine, and a 25-30mm

108 long incision was made using a 10-guage sterilized scalpel approximately 15mm offset of, but parallel to, the ventral midline. Sex was determined by visual inspection of the gonads or by direct observation of reproductive material (i.e. running milt). A sterilized transmitter was then inserted and positioned anteriorly into the body cavity. The incision was closed with 2 interrupted horizontal mattress sutures using 4-0, non- absorbable, nylon monofilament suture material, and a 19mm semi-circular needle.

Upon closing, the incision area was again thoroughly irrigated with Stanhexidine.

Following surgery, the bass was transferred to a flow-through holding tank. When proper equilibrium returned, bass were released back to the water near the capture site. Times of anesthesia induction, surgical procedures (including measurements and sample collection), and post-surgical recovery time are summarized in Table 4-1.

Collection and tagging of Striped Bass was conducted under Fisheries and

Oceans Canada Scientific License #322857 and Acadia University Animal Care Protocol

#06-10. As in Chapter 2, posters which described the tracking program, indicated the anatomical positioning and description of tags, and provided contact information to report recaptured fish, were placed at common fishing locations as well as other areas that anglers frequent (post offices, gas stations, convenience stores, tackle shops, etc.)

(Appendix 4-B). Similar information was also posted on the recreational fishing website: www.NovaScotiaFishing.com. No monetary reward was offered for the return of tag information.

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4.2.4 Receiver Moorings

Custom modified A2 Model SUB streamlined instrument floats (Open Seas

Instrumentation, Musquodoboit Harbour, Nova Scotia) housed a VEMCO VR2w receiver attached directly to the fiberglass strongback of a Teledyne Benthos 875-T acoustic release (Teledyne-Benthos, North Falmouth, Mass., USA). Two 316 stainless steel clamps connected the two instruments which were then installed within the sub float and bolted to two external stainless steel brackets. Floatation was provided by two 13” diameter, air-filled, VINY Ball trawl floats which contributed 35kg of positive buoyancy

(Figure 4-2). Moorings consisted of 4 scrap-sourced steel crusher knuckles totaling approximately 200kg. Individual knuckle weights were connected using ½” diameter galvanized steel chain passed through the eyelet opening of each weight (Figure 4-2).

The chain was secured using a bolted ½” galvanized steel safety shackle and pinned with a stainless steel cotter pin. A 2m riser of ½” galvanized chain was connected at its terminus to the bottom of a ½” stainless steel universal anchor shackle. The lower end of the shackle featured a swivel mechanism, and the upper end a gimbaled pivot joint.

The pivoting end was connected to a 5/16” stainless steel D-shackle which connected to the bottom of the 875T acoustic release when closed. Connection points were tacked with stainless steel welds to prevent premature opening.

4.2.5 Mooring Deployment

In total, 22 moored VR2w acoustic receivers were positioned in two array groupings to detect and log tag transmissions of acoustically tagged Striped Bass within

Minas Passage (Table 4-2). Receiver deployments occurred in two stages. Ten receiver

110 moorings were deployed on June 22, 2010 in a dense array within the FORCE test site surrounding the position of the OpenHydro turbine (Figure 4-3, top panel). An additional twelve receiver moorings were deployed by the Ocean Tracking Network (OTN) in collaboration with Acadia University on July 14 th , 2010, in a linear array spanning the

Minas Passage. The Ocean Tracking Network array (MPS) was positioned approximately

2.5km east of the FORCE demonstration site array (FORCE) (Figure 4-3, bottom panel).

Both deployments were conducted from the port of Parrsboro, NS using a chartered fishing vessel.

Results of range and performance testing of VEMCO acoustic telemetry equipment within Minas Passage (Chapter 3) were used to inform the study design. We used the V13P-1H tag which was the largest and most powerful tag that could be carried by both sub-adult and adult Striped Bass. Given the expected detection range of the V13 tag model, receiver moorings were spaced at approximately 400m and 200m intervals within the OTN-MPS and FORCE arrays, respectively. Despite this spacing, it was expected that detection efficiency would be low under peak periods of tidally-driven current flow (>2m/s depth-averaged speed). Receivers in the FORCE array were positioned densely in an attempt to detect sequential detections, and therefore paths of movement, for individual bass travelling near the OpenHydro TISEC device. The linear deployment of the OTN-MPS array crossing Minas Passage provided a unique research opportunity to investigate Striped Bass distribution across the entire Minas Passage as well as depth distributions over a broad range of available depths.

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Station deployment positions were pre-programmed using Fugawi Marine

Navigation software (Version 4.0, Northport Systems Inc., Toronto, ONT), which was also used for precise vessel navigation to each station position. Prior to approaching each station, a mooring was assembled near the stern of the vessel. The anchor weight and riser were moved to the open stern tailgate, and then attached to the instrument floatation package. Fully assembled moorings were approximately 2m in height. On the final approach toward the station the floatation package was placed into the water over the stern. When on station, the anchor weight was moved off the tailgate into the water, and the entire assembly released. Deployments generally occurred near high water slack (at the end of flooding tide, through the beginning of ebbing tide) when tidal current velocities were reduced (<1m/s). Given surface current velocities, controlled drifting of the vessel onto the station position was often required.

4.2.6 Mooring Recovery

Station recovery began November 23 rd , 2010 and continued on November 29 th ,

2010 (Table 4-2). On arrival at the station, the transducer of a UDB-9000-LF deck box

(Teledyne Benthos, North Falmouth, MA USA) was lowered over the side of the vessel.

The deck box and transducer were then used to transmit a series of acoustic communications to the 875-TD acoustic release. The 875-TD functions by rotating a shaft, which releases an arm holding a 5/16” stainless steel drop shackle. When released, the drop shackle separates the instrument package from the riser chain and anchor weight, which are sacrificed. The floatation of the SUB buoy brought the

112 instrument package to the surface for collection and receiver data offload. All receiver stations were recovered with the exception of MPS-04 and FORCE-E5.

4.2.7 Data Treatment

VEMCO VUE software was used to download VEMCO receiver log files (VRLs) from recovered receivers. Receiver clock drift is a known issue that can occur in all study environments, but can be exaggerated by extended deployment periods (D. Webber –

VEMCO, pers. comm. Year??). Using the VUE software, a linear correction factor was applied to individual receiver VRL files to adjust for clock drift (Table 4-2). Drift corrected

VRL files were then compiled into a VEMCO Database (VDB) containing the detection histories of all receivers deployed during the study season. All transmitters used in this study featured internal pressure sensors. Raw pressure sensor values were converted to depth (m, relative to surface) within the VDB using transmitter specific slope and intercept values provided by VEMCO. A complete detection history for the study was then exported from the VUE program into .csv spreadsheet format for further manipulation. Detection histories of individual bass were separated and ordered sequentially.

In some cases, a single tag transmission from an individual Striped Bass was logged by more than one receiver, creating “multiple detections” of a transmission.

Multiple detections are valid, and provide useful information on the transmission range at time of detection. Identification of multiple detections and their removal from subsequent analysis is a common practice as pseudoreplication is an important consideration in acoustic telemetry studies (Rodgers and White, 2007). However, it can

113 be difficult to determine which detection to retain from a group of multiple detections.

The first logged detection may not yield the best estimate of fish position because individual receiver clocks drift independently of one another. Linear drift correction corrects the time of detection relative to the other detections logged on the same receiver, but due to independent drifting is not able to standardize corrections between nearby receivers that may have logged multiple detections. To avoid spatial bias by selecting incorrect positional estimates, multiple detections were not filtered. In analyses of detection depth data (m below surface), multiple detections were filtered to remove duplicate recordings of the same depth across multiple stations.

This study also includes Striped Bass detection data from nine intertidal receiver stations that were placed within Minas Basin (Figure 4-1) for an unrelated study of

Atlantic Sturgeon movements (M. Stokesbury, Acadia University). This data provided interim locations of Striped Bass when not present in Minas Passage.

4.2.8 Movement Analysis

Daily presence/absence of each tagged bass was determined for each of the two acoustic receiver arrays. A scatterplot of the daily presence/absence detection data was prepared to demonstrate temporal residence patterns within the system and movements between arrays. Striped Bass not detected by receiver arrays within Minas

Passage were not considered in further analyses.

The number of days each bass was available for detection within the system, termed the “potential detection period”, was based upon tagging date (or date of receiver installation in cases where fish were tagged in advance of receiver

114 deployment), and time of first receiver recovery (November 23, 2010). To standardize variable release dates between individuals, a proportional presence index ( Ip) was calculated for each bass,

Ip = N d / N p (Eq. 4-1) where Nd is the total number of days in which an individual Striped Bass was detected within Minas Passage, and Np is the number of days an individual could potentially have been detected within the system (Topping et al., 2006; Sagarese and Frisk, 2011).

The number of unique detection interaction events with Minas Passage was determined for each Striped Bass. An interaction was defined as a period of continuous detection with no gap between successive detections greater than 60 mins. Consecutive detections less than 30 minutes apart indicated directed movement between receiver arrays. Distances between detecting receiver stations and time between consecutive detections were used to estimate straight line travel speed (m/s and body lengths/s) between arrays.

A Rayleigh Test of uniformity was used to examine the distribution of detection times for each receiver array (MPS and FORCE). Wilcoxon signed-rank tests were used to compare Striped Bass presence and depth between tag release sites (Stewiacke and

Grand Pré), and between sexes for bass released from the Stewiacke release site.

Pearson’s correlational coefficients were used to quantify the association between detection depth and current speed, as well as Striped Bass body size (TL). Kernel Density plots were used to visually examine Striped Bass depth distribution by tagging group

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(Stewiacke and Grand Pre) at each array (MPS and FORCE). All statistical tests were conducted using R (R Core Development Team, 2014), and were considered significant at α = 0.05.

4.2.9 Assumptions

The analysis and interpretation of acoustic telemetry data from Minas Passage required that several assumptions be made:

1) Tags of the same model behaved similarly with equal probability of detection;

2) Tags were functional from the period of activation until the battery expiration date provided by VEMCO;

3) Striped Bass retained their tags throughout the monitoring period;

4) Acoustic receivers behaved similarly, despite known differences in location and depth of their moorings and variability in current regime at each station (Appendix 4-C);

5) Clock drift during the duration of deployment was linear; and

6) Mooring positions did not change greatly (<50m) over the course of the detection period.

At high depth-averaged current speeds (>1.5m/s), transmissions emitted within expected areas of overlapping receiver coverage may not be detected (see Chapter 3).

The tag data from this tracking study therefore underestimate tagged bass presence and activity in Minas Passage.

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4.3 RESULTS

4.3.1 Post Tagging Survival

Survival of Striped Bass post-tagging was very high (>98%), as indicated by detection of 79 of 80 tagged bass at receiver positions located away from the tagging sites. Overall, 52 of 80 (65%) bass tagged in this study were detected within Minas

Passage during 2010. The other 27 Striped Bass were detected only by receivers in intertidal locations within Minas Basin.

4.3.2 General Detection Patterns

A total of 3266 unique detections were recorded between June 27 – November

23, 2010 on the MPS and FORCE arrays. Of these, 2598 (79.5%) were recorded on the

MPS array, with the remaining 668 (20.5%) of detections being recorded on receivers within the FORCE array (Table 4-3). Receiver data were examined to determine the number of total detections, number of unique bass detected, the distribution of total detections by receiver, and the distribution of detections with respect to tidal stage

(ebb, flood, and slack) (Table 4-3). All 20 recovered receiver stations within Minas

Passage logged Striped Bass tag transmissions; on average, there were 163 logged detections (SD=±107.5) and 18 bass detected (SD= ±7.6) per receiver.

Detection records were pooled for the study period and examined by hour of the day in which detections were logged (Figure 4-4). Rayleigh’s tests of circular uniformity determined that the distribution of hourly detections did not deviate significantly from a uniform distribution, with no mean resultant time observed for the OTN-MPS array

(Rayleigh test, P > 0.001, 4 = 0.09, n = 2603) or the FORCE array (Rayleigh test, P > 0.001,

117 r = 0.17, n = 663). Similar comparisons could not be made at the level of individual

Striped Bass due to small numbers of detections of some individuals.

Total daily detections did not vary significantly with tidal range (Pearson’s

Correlation: r = 0.127, p = 0.11) (Figure 4-5). No pattern in detections with tidal stage

(ebb vs flood) was evident (Table 4-3), however a comparatively large number of detections were logged during the slack water period given the limited time during which current speeds were <0.5m/s (Appendix 4-C). In general, detections decreased strongly with increasing current speed on both ebb and flood stages (Figure 4-6).

Detections at the MPS array decreased strongly with increasing current speed, however, this pattern was not as evident at the FORCE array (Figure 4-7).

4.3.3 Temporal Distribution

Tagged bass were released within the Stewiacke River prior to installation of receiver moorings in Minas Passage. The first detection of a Striped Bass from the

Stewiacke River release group was recorded by receivers at FORCE on June 27, 2010.

Bass were subsequently detected by the MPS receiver array on the day of that line deployment (July 14, 2010).

Tagged Striped Bass were present within the Minas Passage throughout the study duration, however, individual activity was variable (Figure 4-8). Tagged bass were detected on 110 of 156 (70.5%) days that receivers were deployed. The OTN-MPS array logged detections on 102 of 139 (73.3%) days of its deployment, with an average of 25

(max = 130) detections/day. Striped Bass were detected at the FORCE array during 49 of

156 (31.4%) of its days of deployment, with an average of 13 (max = 70) detections/day.

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Striped Bass released from the Stewiacke River site accounted for 3059 (93.6%) of 3266 detections, with the Grand Pré site releases contributing the remaining 216

(6.4%) detections. Stewiacke-released bass were detected on 106 of 156 (67.9%) possible detection days, with an average of 28 (Max = 150) detections/day. Grand Pré- tagged bass were detected within Minas Passage on 21 of 117 (17.9%) possible detection days, with an average of 10 (Max = 30) detections/day.

Individual Striped Bass were detected within the Minas Passage, on average, on

5 days (Range = 1-22 days) during the study period. A proportional presence index ( Ip) was determined by relating the number of days an individual bass was detected within

Minas Passage to the number of days a bass could potentially have been detected.

Values of Ip ranged from 0.01-0.17, and averaged 0.04 (SD = ±0.03, n = 52) (Table 4-4).

Significant differences were found in Ip values between tagging groups (Wilcoxon Test:

W = 103.5, p = 0.002) with Stewiacke-released bass having greater Ip values. No significant difference was found in Ip values between sexes (Wilcoxon Test: W = 195, p =

0.912) within the Stewiacke River tagging group.

4.3.4 Number of Interactions

The number of unique detection interactions within Minas Passage was determined for individual Striped Bass (Table 4-4) and ranged from 1-24, and averaged 6 interactions per bass (SD = ±5.19, n = 52). A significant difference in the number of encounters was found between tagging groups (Wilcoxon Test: W = 90, p = 0. 001), indicating a greater number of unique detection interactions by Stewiacke releases. No significant difference was found in the number of encounters between sexes (Wilcoxon

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Test: W = 198, p = 0.978) within the Stewiacke River tagging group. The number of unique detection interactions and bass total length (TL) were positively and significantly correlated (Pearson’s Correlation: r = 0.399, p = 0.003). Further examination of detection patterns across seasons was limited by the timing of receiver deployments relative to the release of transmitter implanted bass.

4.3.5 Spatial Distribution

The distribution of detections in Minas Passage was broad with no single receiver station dominating in logged transmissions, however the number of individual bass detected, and number of total detections per station, were greater in the central and southern portions of Minas Passage (MPS-05 through MPS-12) (Table 4-3). Spatial detection density plots were produced to indicate the number of detections logged by each receiver station for individual Striped Bass (Figures 4-9 and 4-10). Of the 43 bass tagged in the Stewiacke River, 40 (93%) were detected within Minas Passage (Figure 4-9,

Table 4-4). In comparison, only 12 of 37 (32%) Striped Bass tagged at the Grand Pré site were detected within the Minas Passage (Figure 4-10, Table 4-4); these bass were generally smaller in body size. Detections at the FORCE site, and within 400m of the

OpenHydro turbine, included 21 of 40 (52%) Stewiacke releases and 4 of 12 (33%) Grand

Pré releases.

On average, tagged Striped Bass were detected by 7 of 20 receiver mooring stations (Range 1-20). A significant difference in the number of receivers logging detections was found between tagging groups (Wilcoxon Test: W=113, p = 0.005) with

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Stewiacke releases detected by more stations; there was no significant difference in number of receivers detecting males and females within the Stewiacke tagging group

(Wilcoxon Test: W= 198, p = 0.978).

One transmitter-implanted Striped Bass, also tagged with an external Floy ID tag, and released at the Grand Pré site was recaptured by an angler at the same site four days later. No other tag returns were reported by local or long range fisheries during the

2010 season. Additionally, no reports were received regarding detection of acoustically tagged Striped Bass by telemetry arrays outside of those used in this study.

4.3.6 Travel Rate

Minimum travel rates for individual striped bass were determined from consecutive detections (occurring less than 30 min apart) between receiver arrays (3 km or more between receivers). A total of 15 travel speeds, from 14 individual bass, were estimated (Table 4.5), assuming straight line movement between receivers. Average travel speed was 2.34 m/s (SD= ±0.3, N= 15, Range= 1.8-2.9m/s). Relative to Striped

Bass body size the average travel speed in body lengths per second was 3.5 BL/s (SD=

±0.7, N= 15, Range= 2.4–4.9 BL/s).

4.3.7 Depth Distribution

A moderate but significant positive correlation was found between detection depth and Striped Bass total length (TL) (Pearson’s Correlation, r = 0.41, p < 0.001,

Figure 4-11), and between detection depth and depth-averaged current speed at the

FORCE array (Pearson’s Correlation, r = 0.419, p < 0.001, Figure 4-12).

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Boxplots were used to indicate Striped Bass detection depth distributions relative to the water column depth (MWL, m) at both the MPS (Figure 4-13) and FORCE

(Figure 4-14) array locations. Note that in some instances the detection depths were greater than the expected bottom depth of the receiver mooring position. Kernel- density plots were used to visualize detection depth distributions relative to ebb and flood tidal stages, at the MPS (Figures 4-15) and FORCE arrays (Figure 4-16), respectively. Striped Bass swimming depths were variable, with individuals being recorded by MPS receivers at depths ranging from the surface to 96.3m (Figure 4-13 and

Figure 4-15, Table 4-6), and from the surface to 53.6m (max depth 55m MWL) at the

FORCE demonstration site array (Figure 4-14 and Figure 4-16, Table 4-6). Detection depths between tag groups were found to be significantly different, with Stewiacke releases detected deeper than Grand Pré releases, at both the MPS array (Wilcoxon

Test, W=44540, p= < 0.001) and the FORCE array (Wilcoxon Test, W=2095, p = <0.001).

A depth effect was noted with tidal stage (ebb vs flood); bass were detected in deeper waters during flood tides at both the MPS (Wilcoxon Test, W= 197098.5, p =

<0.001) and FORCE (Wilcoxon Test, W= 8412.5, p = <0.001) arrays. Female bass depths were significantly deeper than males at both the MPS (Wilcoxon Test, W=243280, p =

<0.001) and FORCE (Wilcoxon Test, W= 15523, p = <0.001) array locations (Figure 4-17).

Striped bass were also significantly deeper at night than during the day at both the MPS

(Wilcoxon Test, W= 405556.5, p = < 0.001) and FORCE (Wilcoxon Test, W= 15609.5, p =

0.0048) array locations (Figure 4-18).

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4.4 DISCUSSION

4.4.1 Spatial and Temporal Distribution

All but one of the 80 tagged Striped Bass were detected by receivers deployed in the Minas Passage (MPS and FORCE demonstration site arrays) and Minas Basin. This indicates that handling and surgery effects had minimal effects on the survival of Striped

Bass. Tag expulsion and capture/retention are unlikely to have influenced this study.

The lone bass which went undetected was tagged in May at the Stewiacke River site and was of legal retention size (≥68 cm TL). This fish may have gone undetected due to post- surgical mortality, tag expulsion, retention within the recreational or commercial- bycatch fishery, predation, or due to lack of movements within detection range of receivers. Receiver Stations MPS-04 and FORCE-E5 were never recovered, creating some gaps in detection coverage.

Bass movements spanned the width of the Minas Passage. Detections of Striped

Bass were logged by all 20 recovered receivers, and two bass (sizes?) were detected by all 20 receivers. It is not surprising that Striped Bass were detected more commonly on the MPS array than the FORCE test site array given the greater distance covered by the

MPS array. The majority of detections occurring within Minas Passage were from large- bodied bass (>55 cm TL), that were mostly released from the Stewiacke River tagging site. While there was little evidence pointing to specific movement pathways or corridors, logged tag transmissions and the total number of bass detected were greater in the central and southern portions of Minas Passage.

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Regular presence of Striped Bass within Minas Passage throughout the monitored July-November period suggests that the tagged bass were not long distance migrants but rather remained relatively localized within the upper Bay of Fundy. Bass did not appear to remain resident within Minas Passage, but rather utilized the area for brief periods on multiple occasions throughout the study. Presence of most of the

Striped Bass from the Stewiacke River tagging group within Minas Passage highlights the importance of this area to reproductively mature Striped Bass which are assumed to be of local SR origin.

The SR stock contingent that overwinters in freshwater of the Shubenacadie

River-Grand Lake may possess a limited marine distribution (Douglas et al., 2003), as evidenced by very few tag recaptures beyond Minas Basin (Bradford et al., 2012; DFO,

2014). In contrast, Rulifson and Dadswell (1995) indicated that larger-bodied individuals of local origin (no specific size reference was provided) could be expected to migrate from Minas Basin through Minas Passage following completion of spawning in the SR system. Our telemetry results indicated that the range of large-bodied (>55cm TL)

Striped Bass, tagged within the SR system, extended beyond Minas Basin, minimally reaching Minas Passage. However, lack of receiver infrastructure beyond these locations limits determination of migration further seaward into the BoF system.

Results of this telemetry study largely confirmed the patterns indicated by the conventional tagging mark-recapture study outlined in Chapter 2, which suggested body size/age differences in habitat use. Larger Striped Bass from the Stewiacke River system

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(>55 cm TL) were detected by intertidal receivers within Minas Basin sporadically until early August after which they were detected by receivers within Minas Passage nearly exclusively, although not continuously. Bass tagged at the Grand Pré site were of smaller body size (<55cm TL) and revealed a limited range of movement that was almost exclusively contained within Minas Basin; in some cases, there was continuous daily presence in the submerged intertidal zone. Striped Bass tagged at the Grand Pré site in

August showed a high level of site fidelity and were present within Minas Basin until at least late October, at which time intertidal receivers were recovered. The extent of migration of Striped Bass has been suggested to increase with increasing body size

(Rulifson and Dadswell, 1995; Collette and Klein-MacPhee, 2002), and may reflect size- dependent habitat segregation based on feeding selectivity or environmental preferences, specifically temperature (Coutant, 1985; Collette and Klein-MacPhee, 2002;

Nelson et al., 2010)

Strong summer patterns of site residency and inter-annual site fidelity of Striped

Bass (56.4 - 91.4cm FL) acoustically tagged within a New Jersey estuary have been reported by Ng et al., (2008). While this size range corresponds well with those fish tagged from the Stewiacke River (55.4 - 82.4 cm TL), they did not exhibit strong site residency behavior. In contrast, bass tagged and released from the Grand Pré site

(generally smaller in size; 38.0-67.4cm TL) were found to exhibit a high degree of residency within Minas Basin which offers food resources of sufficient quality and quantity to support long-term occupancy during the important summer feeding/growing season. While site fidelity could not be shown from the telemetry data, conventional

125 tag results (see Chapter 2) indicated site fidelity of individual bass across multiple study years; it is likely that similar patterns would be shown with a multi-year telemetry study.

This study does not provide information on use of marine habitat by Striped Bass during winter as the monitoring period did not extend into winter months and most tag batteries would have expired early in the winter season (see Figure 4-8). However, four tagged Striped Bass were detected in Minas Passage into late November just prior to receiver recovery. The reduced presence of most tagged Striped Bass by the end of

October may be indicative of movement to overwintering areas, either to known freshwater sites within Shubenacadie River-Grand Lake, NS or to unknown marine locations either within Minas Basin or the Bay of Fundy (Rulifson and Dadswell, 1995;

Bradford et al., 2012). The overwintering locations of Striped Bass within the Bay of

Fundy, particularly identification of potentially critical marine wintering habitat, remains a knowledge gap requiring further investigation (COSEWIC, 2012).

4.4.2 Travel Speed

Striped Bass travels speeds have not been widely investigated. In this study travel speeds through Minas Passage were determined from sequential detections between receiver arrays separated by less than 30 minutes. Average travel speeds were

3.5 BL/s (range: 2.4-4.9 BL/s). The two highest speeds (4.8 and 5.4 BL/s) corresponded to the two smallest bass in the sample. Maximum sustained swimming speeds of adult striped have been found to range between 2.9-3.3 BL/s (Freadman, 1979; Collette and

Klein-McPhee, 2002), which corresponds well with the values obtained in this study. It

126 should be noted that travel speed in the present study includes the influence of tidal currents and therefore may not be truly reflective of the swimming speed of the fish.

4.4.3 Depth Distribution

There has been limited study of Striped Bass depth distribution in open marine environments (Graves et al., 2009). Most studies have focused on latitudinal movements rather than longitudinal onshore/offshore movements (Kneebone et al.,

2014) and Striped Bass in shallow estuarine and river systems (Haeseker et al., 1996; Ng et al., 2007). Swimming depths occupied by Striped Bass are of particular relevance in

Minas Passage where the potential risk of interaction with TISEC infrastructure is being assessed.

Receivers deployed in this study were positioned across areas featuring high bathymetric relief and the detection range of each receiver covered a wide range of depths. Receivers positioned on highly sloped seabed or near a deep drop-off often detected Striped Bass at depths deeper than the estimated receiver mooring position, a pattern also reported by O’Toole et al. (2010). The exact latitude and longitude of detection could not be determined from within the receiver’s detection range, therefore it was not possible to define a water column depth for each detection. This prevented reliable determination of Striped Bass proportional water column use and height above bottom.

Large-bodied Striped Bass (>55 cm TL) released from the Stewiacke River tagging site showed variable depth distribution within Minas Passage, with detections

127 throughout the water column. These bass were generally associated with the upper half of the water column, yet short-term movements to greater depths, utilizing the full water column, were also evident. Graves et al. (2009) indicated that eight very large (94-

122 cm TL) Striped Bass, collected from the Virginia, USA winter fishery and fitted with pop-up archival satellite tags, spent >90% of the monitored period within the upper

10m of the water column, but occasionally exhibited short-term movements to depths of up to 25m. Study site information was not provided to indicate the available water column depth in which fish were found, and therefore it is not possible to compare proportional use of the available water column with our results.

Within Minas Passage, use of the entire water column by large-bodied Striped

Bass during the summer-fall period could indicate feeding activity, or may possibly suggest tidal staging behavior, where deeper portions of the water column are used in seeking refuge from high current speeds. Selective tidal transport, incorporating tidal staging behavior, has been indicated for other species (Forward and Tankersley, 2001;

Gibson, 2003; Bradford et al., 2009) and may be a strategy employed by Striped Bass.

Detection data indicates that the near-shore southern portion of Minas Passage, where a large eddy forms along the Blomidon Peninsula during flood tide (Karsten et al., 2008), was used by many individual Striped Bass. This area features lower current speeds (i.e. increases likelihood of tag detection) and thus offers a refuge and foraging area for

Striped Bass and other species.

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Overall, smaller-bodied (<55cm TL) Striped Bass released from the Grand Pré tagging site were detected much less frequently than the Stewiacke-released bass, at both receiver arrays in Minas Passage. Small-bodied bass were also found to associate more closely with the surface, at depths <10m, than larger bass. It is suspected that bass of smaller body size are less capable of positioning themselves within the powerful currents of Minas Passage and thus tend to reside in the lower flow, near-shore areas to feed. At both Minas Passage receiver arrays, Striped Bass were significantly deeper in the water column during flood tide, which generates faster current speed and more turbulence than the ebb tide (Karsten et al., 2008). It is conceivable that bass utilize deeper depths during flood periods to avoid high turbulence at the surface (tidal staging). However, the effect observed also may be due to decreased detection efficiency on the flood tide (Melnychuk, 2012a; see Chapter 3). The likelihood of successful detection for a transmission emitted within turbulent surface water is expected to be less than a transmission emitted in deeper, less turbulent water. This effect remains to be tested.

Range testing results (see Chapter 3) showed that detection efficiency decreased rapidly with both increased current speed and increased tag-to-receiver distance.

Although few detections of Striped Bass occurred during very high current speeds (>2.5 m/s), it is not possible to conclude that tagged Striped Bass were absent at these times.

These results highlight the critical importance of careful consideration of telemetry performance limitations when making conclusions regarding presence of fish at high flow, tidal energy development sites.

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Swimming depth of Striped Bass within Minas Passage is an important consideration in determining potential risk of interaction with TISEC devices deployed within the FORCE demonstration area. Turbine design, location, and deployment considerations of various proposed TISEC devices may have important implications on the level of potential risk for interaction with Striped Bass. Results of this study indicate that large Striped Bass (>55 cm TL) may be at greater risk, compared to smaller bass, of encounter with TISEC devices installed in bottom frames (e.g. gravity base). Tidal devices positioned within the top 20 m will pose greater risk to smaller bass which tend to occupy the surface waters when present in the Minas Passage.

4.4.4 Conclusions and Recommendations

This study provides the first acoustic telemetry investigation of Striped Bass movements within the marine distribution of the Bay of Fundy population. As the first examination of Striped Bass activity in Minas Passage, this study serves as a proof-of- concept for future use of acoustic telemetry in monitoring movements of Striped Bass, and other fishes, in Minas Passage and other high flow sites globally.

Striped Bass exhibited size-differentiated habitat use patterns, with bass of smaller body size (Grand Pré releases, <55cm TL) exhibiting site residency patterns within Minas Basin and showing limited movements within Minas Passage and the

FORCE test site. Striped Bass tagged at the Stewiacke River site (spawning adults, >55cm

TL) were detected regularly within Minas Passage and the FORCE test site. Acoustic telemetry methods confirmed that reproductively mature Striped Bass, of assumed SR

130 stock origin, possess a range that extends minimally to Minas Passage. Striped Bass were present within Minas Passage throughout the July-November monitoring period.

While not present continually, individual Striped Bass were detected making multiple passes through the monitored areas in Minas Passage and within the FORCE test site.

Intermittent presence throughout the study duration suggests that SR origin Striped

Bass may not undertake long distance migration to the outer Bay of Fundy / Gulf of

Maine system.

This study also provides the first examination of Striped Bass depth distribution within waters greater than 50m. Striped bass were detected over a wide range of depths in Minas Passage (up to 96m). Within FORCE, bass were detected at depths up to 53 m which highlights the potential for Striped Bass to encounter TISEC devices installed at various depths within the FORCE test area. Future research should focus on fish behaviour in the FORCE turbine test area, specifically the detection and evasion of

TISEC devices.

Acoustic telemetry techniques were able to provide considerable advances in resolution over conventional tagging, and permitted examination of temporal and spatial use of Minas Passage by Striped Bass. However, given known limitations of acoustic telemetry performance in the Minas Passage environment (see Chapter 3), we expect that data presented in this study represents considerably less than 50% of transmissions emitted in close proximity (<400 m) to acoustic receivers. Results described should be considered as a minimum level of Striped Bass presence/activity.

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Regardless, Striped Bass use of Minas Passage and the FORCE test site was greater than expected, indicating that these locations are more important to Striped Bass than previously known.

We suggest that future studies undertake longer term monitoring to examine both inter-annual and seasonal variability in habitat use, including winter periods. Use of long life tags would permit the examination of both year-round and multi-year study of fish movements, including the potential to further identify patterns in site residency and fidelity, and home range. Further data collection would also support the development of a predictive model of Striped Bass use of high flow sites, including swimming depth relative to current speed, tidal direction, time of day (day/night), water column depth, fish size, sex, stock origin, etc. This model would be useful in estimating the likelihood of individual Striped Bass interacting with TISEC devices.

Due to limitations in detection performance under peak flows, this study was largely unable to provide information to characterize Striped Bass use of Minas Passage when depth-averaged currents speeds exceeded 2 m/s. Lack of detections during peak flows may be a result of lack of fish presence, reductions in performance/range induced by tidal conditions, or undetected high speed travel through acoustic arrays.

While acoustic telemetry has provided useful insights into the presence/absence and depth distribution of Striped Bass within Minas Passage, it is not the ideal tool for resolving potential interactions of Striped Bass, and other fish species, with tidal energy infrastructure. It is therefore recommended that future studies incorporate near-field spatial scales (<10m) in monitoring of TISEC device demonstration projects using

132 integrated passive and active acoustic instruments. However, extreme conditions found within Minas Passage present unique challenges, and therefore “off-the-shelf” equipment may not be best suited for this environment. Advances in sensor development (including protection), deployment methods and multi-sensor integration may be required.

133

4.5 TABLES

Table 4-1. Summary of 2010 Striped Bass tagging activities and transmitter specifications, by tagging site.

Tagging location Stewiacke River, NS Grand Pré, NS Tagging dates May 10-13, 2010 August 4-16, 2010 Bass tagged 43 37

Size range of bass tagged 55.4 – 82.4 37.7 – 67.4 (FL, cm)

Mean time to anesthesia 2:13 (± 0:21) 1:21 (± 0:13) induction (±SD) (min:sec) Mean time to completion of 5:14 (± 1:25) 3:52 (± 0:43) surgery and procedures (±SD) (min:sec)

Mean time to release post- 4:34 (± 1:40) 2:40 (± 1:08) surgery (±SD) (min:sec)

Tag Model V13P-1H V13P-1H

Tag Output Power 158 dB re 1μPa @ 1m 158 dB re 1μPa @ 1m Transmission delay (sec) 45-95 45-95 Expected Battery Life (days) 214 170

134

Table 4-2. Deployment and recovery metadata summary of acoustic receiver moorings placed in Minas Passage, NS during summer and fall 2010. Stations E1-W5 were situated within the FORCE test site, while Stations MPS01-MPS12 were positioned from north to south, respectively, across Minas Passage. Note that stations E5 and MPS04 were not recovered. Clock drift is expressed as the difference in time between the pc clock at download and the receiver clock at download, negative values indicate that receiver time lagged behind the pc clock, while a positive value indicates that a receiver clock which drifted ahead of the pc.

Array Station Deployment Latitude Longitude Depth Recovery Clock Drift Date (m, MWL) Date (m:ss) FORCE E1 6/22/2010 45.3658 -64.4225 41.8 11/23/2010 2:02 FORCE E2 6/22/2010 45.3643 -64.4240 36.4 11/23/2010 2:54 FORCE E3 6/22/2010 45.3629 -64.4252 40.4 11/23/2010 -3:16 FORCE E4 6/22/2010 45.3640 -64.4213 35.6 11/23/2010 -2:32 FORCE E5 6/22/2010 45.3628 -64.4226 40.6 NA NA FORCE W1 6/22/2010 45.3676 -64.4274 52.2 11/29/2010 -3:57 FORCE W2 6/22/2010 45.3658 -64.4287 42.3 11/23/2010 0:07 FORCE W3 6/22/2010 45.3642 -64.4300 38.0 11/29/2010 0:10 FORCE W4 6/22/2010 45.3675 -64.4300 53.5 11/23/2010 0:28 FORCE W5 6/22/2010 45.3658 -64.4313 45.3 11/23/2010 -1.38

OTN MPS01 7/14/2010 45.3614 -64.3835 29.5 11/23/2010 -1:45 OTN MPS02 7/14/2010 45.3580 -64.3859 46.0 11/23/2010 2:13 OTN MPS03 7/14/2010 45.3548 -64.3883 69.4 11/23/2010 -1:38 OTN MPS04 7/14/2010 45.3513 -64.3905 80.0 NA NA OTN MPS05 7/14/2010 45.3482 -64.3927 81.0 11/29/2010 -3:21 OTN MPS06 7/14/2010 45.3450 -64.3954 84.9 11/29/2010 -0:26 OTN MPS07 7/14/2010 45.3419 -64.3978 117.5 11/29/2010 -1:14 OTN MPS08 7/14/2010 45.3387 -64.4002 117.9 11/29/2010 -2:24 OTN MPS09 7/14/2010 45.3354 -64.4026 92.3 11/23/2010 -1:14 OTN MPS10 7/14/2010 45.3321 -64.4049 66.7 11/23/2010 -2:44 OTN MPS11 7/14/2010 45.3289 -64.4076 43.5 11/23/2010 -2:27 OTN MPS12 7/14/2010 45.3257 -64.4099 33.2 11/23/2010 2:27

135

Array Station Bass No. % % % % Name Detected Detections Total Detection Detection Detection Detections Ebb Flood Slack FORCE E1 11 71 2.17 36.6 29.6 33.8 FORCE E2 17 66 2.02 34.8 40.9 24.2 FORCE E3 12 66 2.02 54.5 12.1 33.3 FORCE E4 15 92 2.82 44.6 13.0 42.4 FORCE E5 NA NA NA NA NA NA FORCE W1 12 172 5.27 53.5 26.7 19.8 FORCE W2 11 33 1.01 45.5 27.3 27.3 FORCE W3 22 107 3.28 53.3 20.6 26.2 FORCE W4 11 31 0.95 64.5 22.6 12.9 FORCE W5 8 25 0.77 28.0 12.0 60.0

OTN MPS-01 19 164 5.02 48.8 31.1 20.1 OTN MPS-02 13 155 4.75 18.1 34.2 47.7 OTN MPS-03 13 129 3.95 37.2 12.4 50.4 OTN MPS-04 NA NA NA NA NA NA OTN MPS-05 22 302 9.25 53.3 16.2 30.5 OTN MPS-06 25 212 6.49 23.1 30.7 46.2 OTN MPS-07 23 329 10.07 16.7 33.7 49.5 OTN MPS-08 28 234 7.16 20.9 42.3 36.8 OTN MPS-09 34 185 5.66 32.4 33.0 34.6 OTN MPS-10 28 297 9.09 21.5 30.3 48.1 OTN MPS-11 29 197 6.03 32.5 28.4 39.1 OTN MPS-12 26 399 12.22 9.8 19.0 71.2* * longest period of flows < 0.5 m/s.

136

Table 4-4. Summary information of Striped Bass (N = 52) detected within Minas Passage, NS. For bass tagged at the Stewiacke River site the date of tag release is relative to the completion of receiver array installation, whereas bass from the Grand Pré site were all tagged and released following deployment of receiver arrays. Receiver recovery began 11/23/2014, and was used as the final possible date a Striped Bass could have been detected. The number of unique days detected (Nd) and the number of potential detection days (Np) were used to calculate a proportional presence index (Ip) to examine individual activity within Minas Passage.

Fish TL Sex Date of Tag Date of First Site of First Date of Last Site of Last Days Potential Presence Unique Stations ID (cm) Release Detection Detection Detection Detection Detected Detection Index (I p) Detection Detected (relative array (N d) Days (N p) Interactions deployment) 1 67.0 F 7/14/2010 8/6/2010 MPS-09 9/3/2010 MPS-12 3 132 0.02 4 6 2 73.6 F 7/14/2010 8/17/2010 MPS-02 10/13/2010 MPS-02 8 132 0.06 10 11 3 69.2 M 7/14/2010 7/29/2010 MPS-05 7/29/2010 MPS-03 1 132 0.01 1 2 5 73.7 F 7/14/2010 7/18/2010 MPS-03 10/29/2010 MPS-09 12 132 0.09 13 16 6 82.4 F 7/14/2010 7/17/2010 MPS-12 10/31/2010 MPS-02 6 132 0.05 6 12 7 73.9 F 7/14/2010 7/27/2010 FORCE-W2 10/23/2010 MPS-05 13 132 0.10 13 12 8 76.8 F 7/14/2010 8/11/2010 FORCE-E1 11/1/2010 MPS-12 5 132 0.04 6 11 9 63.0 M 7/14/2010 7/26/2010 MPS-11 10/18/2010 FORCE-E4 6 132 0.05 7 15 10 67.2 F 7/14/2010 8/23/2010 MPS-12 9/29/2010 MPS-10 4 132 0.03 4 5 11 69.0 M 7/14/2010 8/1/2010 MPS-09 8/9/2010 MPS-01 4 132 0.03 5 11 12 81.7 F 7/14/2010 7/30/2010 MPS-10 11/27/2010 MPS-08 14 132 0.11 17 6 13 78.9 F 7/14/2010 7/26/2010 MPS-07 9/8/2010 FORCE-W1 9 132 0.07 11 20 14 72.0 M 7/14/2010 8/7/2010 MPS-05 8/9/2010 MPS-09 2 132 0.02 3 5 15 70.0 M 7/14/2010 8/1/2010 MPS-05 8/1/2010 MPS-05 1 132 0.01 1 1 16 67.4 M 7/14/2010 7/25/2010 MPS-10 9/22/2010 MPS-08 7 132 0.05 7 6 18 66.5 M 7/14/2010 7/26/2010 MPS-11 9/3/2010 MPS-09 5 132 0.04 6 3 19 75.3 F 7/14/2010 8/4/2010 MPS-09 9/5/2010 MPS-12 7 132 0.05 9 6 20 73.9 F 7/14/2010 7/30/2010 MPS-01 11/1/2010 MPS-W3 7 132 0.05 7 12 21 76.5 F 7/14/2010 8/9/2010 MPS-09 8/23/2010 MPS-08 2 132 0.02 2 6 22 77.7 F 7/14/2010 7/31/2010 MPS-11 8/7/2010 MPS-11 2 132 0.02 3 4 23 76.2 F 7/14/2010 10/20/2010 MPS-01 10/20/2010 MPS-08 1 132 0.01 1 3 24 76.5 F 7/14/2010 10/20/2010 MPS-01 10/20/2010 MPS-03 1 132 0.01 2 3

137

25 63.7 F 7/14/2010 8/4/2010 MPS-01 11/3/2010 MPS-07 5 132 0.04 6 10 26 81.0 F 7/14/2010 8/1/2010 MPS-01 10/12/2010 FORCE-E3 7 132 0.05 8 11 27 68.3 M 7/14/2010 8/26/2010 MPS-06 10/21/2010 FORCE-W3 2 132 0.02 2 3 28 65.3 F 7/14/2010 8/14/2010 MPS-03 8/18/2010 FORCE-E4 3 132 0.02 6 12 29 71.6 F 7/14/2010 7/29/2010 MPS-12 7/29/2010 MPS-11 1 132 0.01 1 2 30 59.5 F 7/14/2010 9/28/2010 MPS-10 11/26/2010 MPS-05 5 132 0.04 5 10 31 79.0 F 7/14/2010 7/20/2010 MPS-08 11/29/2010 MPS-07 13 132 0.10 14 5 32 67.1 M 7/14/2010 8/6/2010 MPS-05 9/17/2010 MPS-11 6 132 0.05 8 9 33 64.4 M 7/14/2010 7/29/2010 FORCE-E2 8/12/2010 MPS-08 4 132 0.03 4 5 34 66.6 M 7/14/2010 8/5/2010 MPS-10 10/15/2010 MPS-09 12 132 0.09 16 18 35 70.6 M 7/14/2010 7/23/2010 MPS-09 7/31/2010 MPS-W3 2 132 0.02 3 6 37 64.8 M 7/14/2010 8/14/2010 MPS-01 10/29/2010 FORCE-E1 22 132 0.17 24 13 38 66.0 M 7/14/2010 7/14/2010 MPS-12 9/8/2010 MPS-09 14 132 0.11 16 8 39 72.5 M 7/14/2010 8/5/2010 MPS-12 9/9/2010 MPS-06 10 132 0.08 13 6 40 71.0 M 7/14/2010 7/13/2010 FORCE-E2 10/24/2010 MPS-08 13 132 0.10 15 20 41 55.4 M 7/14/2010 8/14/2010 MPS-09 8/15/2010 MPS-10 2 132 0.02 2 2 42 74.0 M 7/14/2010 8/4/2010 FORCE-E1 8/15/2010 MPS-09 5 132 0.04 5 5 43 68.1 M 7/14/2010 7/31/2010 MPS-12 10/7/2010 MPS-12 7 132 0.05 10 7 49 46.3 NA 8/4/2010 8/16/2010 MPS-11 10/24/2010 MPS-09 2 111 0.02 2 4 51 38.0 NA 8/4/2010 8/21/2010 MPS-12 10/9/2010 MPS-01 2 111 0.02 3 2 53 39.6 NA 8/5/2010 10/16/2010 MPS-08 10/16/2010 MPS-08 1 110 0.01 1 1 58 45.4 NA 8/6/2010 9/7/2010 MPS-01 9/8/2010 MPS-01 2 109 0.02 2 1 59 45.9 NA 8/6/2010 9/5/2010 MPS-01 9/6/2010 FORCE-W3 2 109 0.02 4 8 60 40.2 NA 8/6/2010 10/5/2010 MPS-10 10/5/2010 MPS-11 1 109 0.01 1 2 62 50.4 NA 8/6/2010 10/10/2010 MPS-05 11/29/2010 MPS-08 4 109 0.04 4 6 68 41.5 NA 8/11/2010 9/12/2010 MPS-12 10/10/2010 MPS-09 2 104 0.02 3 3 73 43.8 NA 8/12/2010 11/6/2010 MPS-01 11/13/2010 FORCE-W3 2 103 0.02 3 12 74 39.9 NA 8/12/2010 8/28/2010 MPS-09 11/1/2010 MPS-06 3 103 0.03 4 6 76 39.5 NA 8/13/2010 10/17/2010 MPS-09 10/17/2010 MPS-09 1 102 0.01 1 1 80 48.5 NA 8/12/2010 10/8/2010 MPS-11 10/17/2010 MPS-12 2 103 0.02 2 2

138

Table 4-5. Summary of Striped Bass travel speeds through Minas Passage between the OTN-MPS and FORCE receiver arrays. Travel speeds between arrays are calculated from consecutive detections during periods of <30 min. Striped Bass total length (TL) at time of tagging was used to convert travel speed to body lengths per second (BL/s).

Fish TL (cm) Sex Starting Ending Starting Ending Travel Travel Number Station Station Current Current Speed Speed Speed Speed (m/s) (BL/s) (m/s) (m/s)

5 73.6 F MPS03 E4 0.8 1.5 2.3 3.2 7 67.2 F E4 MPS06 1.7 1.2 2.6 3.9 9 78.9 F E2 MPS06 1.7 1.2 2.5 3.1 11 63.0 M E4 MPS07 1.6 1.1 2.5 3.9 13 77.8 M MPS02 E4 1.3 2.0 2.6 3.4 20 76.2 F E1 MPS02 1.9 1.4 2.9 3.7 28 79.0 F MPS03 E3 1.2 1.8 2.3 2.9 34 77.7 F MPS02 E4 1.2 1.7 1.9 2.4 35 70.6 M MPS01 W3 1.2 0.4 2.9 4.1 37 64.8 M MPS03 E4 1.0 0.9 2.0 3.1 37 64.8 M E3 MPS03 0.3 0.4 2.2 3.3 38 66.0 M E4 MPS03 0.1 0.6 1.8 2.8 40 71.0 M E4 MPS05 1.5 1.0 2.2 3.1 59 45.9 NA MPS01 E2 1.2 2.2 2.2 4.8 74 43.8 NA W3 MPS06 0.2 0.5 2.2 4.9

139

Table 4-6. Summary of depth distributions of individual acoustically tagged Striped Bass detected by array. Depth data is filtered for duplicate detections.

Array Fish TL Depth Mean Depth SD Min Max ID (cm) Detections (m) from (m) Depth Depth (N) surface (m) (m) FORCE 2 73.7 30 8.78 2.64 5.7 16.7 FORCE 5 73.6 13 36.92 15.98 13.6 53.6 FORCE 6 67.0 4 7.93 0.66 7 8.4 FORCE 7 67.2 4 14.85 5.77 10.1 22.4 FORCE 8 81.7 15 47.71 5.03 38.3 55 FORCE 9 78.9 11 20.51 4.71 11.9 26.8 FORCE 11 63.0 4 21.23 4.29 15.8 25.1 FORCE 12 77.8 18 32.91 17.83 4 47.5 FORCE 20 76.2 20 23.19 10.59 8.8 36.9 FORCE 26 71.6 11 29.26 5.31 20.7 39.1 FORCE 27 59.5 1 41.80 NA 41.8 41.8 FORCE 28 79.0 24 40.28 5.99 29.5 49.3 FORCE 33 76.5 1 10.10 NA 10.1 10.1 FORCE 37 64.8 61 11.42 11.06 0 38.3 FORCE 38 66.0 4 3.60 2.27 2.2 7 FORCE 40 71.0 46 21.00 14.66 0.9 43.5 FORCE 43 77.5 44 19.61 8.99 2.2 35.6 FORCE 59 45.9 17 10.64 9.83 1.8 33 FORCE 62 50.4 2 10.80 9.62 4 17.6 FORCE 73 39.2 18 2.58 0.84 1.8 4.8 FORCE 74 43.8 1 4.40 NA 4.4 4.4 MPS 1 82.4 24 29.53 18.53 6.6 62.9 MPS 2 73.7 45 9.49 13.10 1.8 64.2 MPS 3 71.4 4 53.20 1.51 51.4 55 MPS 5 73.6 59 31.98 19.26 2.2 88.8 MPS 6 67.0 25 10.32 11.60 0.9 44 MPS 7 67.2 53 33.05 16.07 2.6 59.8 MPS 8 81.7 31 37.95 7.94 2.2 55 MPS 9 78.9 26 34.03 13.60 13.6 56.3 MPS 10 72.0 7 32.49 11.27 19.8 55.8 MPS 11 63.0 35 36.70 17.21 14.5 76.1 MPS 12 75.8 91 27.02 19.83 2.2 96.3 MPS 14 67.4 5 31.66 26.48 9.2 61.6 MPS 15 69.0 1 47.90 NA 47.9 47.9 MPS 16 70.0 15 26.21 14.41 8.4 48.8 MPS 18 75.3 9 29.84 14.98 17.1 55.4 MPS 19 66.5 38 29.95 12.31 9.7 64.2

140

MPS 20 76.2 7 13.14 10.91 4 27.3 MPS 21 76.5 16 46.91 4.28 40 52.3 MPS 22 63.7 8 43.69 16.24 4.8 55.4 MPS 23 81.0 7 13.00 4.92 9.2 22.9 MPS 24 68.3 7 3.57 1.90 0.9 7 MPS 25 65.3 39 22.86 13.00 5.3 47.9 MPS 26 71.6 18 50.11 9.40 39.1 68.6 MPS 27 59.5 15 16.94 12.15 7 46.6 MPS 28 79.0 6 22.20 14.73 5.3 40.5 MPS 29 67.1 2 31.25 2.47 29.5 33 MPS 30 64.4 46 27.30 23.79 5.3 83.5 MPS 31 66.6 172 26.72 8.49 3.5 63.8 MPS 32 73.9 25 18.30 15.00 1.8 43.1 MPS 33 76.5 10 48.93 9.61 35.6 71.2 MPS 35 70.6 9 15.26 18.30 0 47.9 MPS 37 64.8 157 1.03 3.69 0 23.3 MPS 38 66.0 66 17.80 10.47 1.3 41.3 MPS 39 72.5 22 20.34 21.87 0 53.2 MPS 40 71.0 40 18.87 10.94 4.4 42.2 MPS 41 55.4 1 39.60 NA 39.6 39.6 MPS 42 74.0 2 33.40 28.57 13.2 53.6 MPS 43 73.9 91 29.25 15.20 4 72.1 MPS 49 40.7 16 0.11 0.45 0 1.8 MPS 51 48.9 23 6.35 6.68 0.4 18.5 MPS 58 45.4 5 11.70 6.74 4.4 20.7 MPS 59 45.9 4 14.83 8.32 2.6 21.1 MPS 60 40.2 3 0.43 0.45 0 0.9 MPS 62 50.4 45 8.60 6.63 0 17.6 MPS 68 41.5 31 2.59 0.86 0 4 MPS 73 39.2 23 1.47 0.99 0 4 MPS 74 43.8 15 15.77 10.70 1.3 29 MPS 76 67.4 2 3.30 0.99 2.6 4 MPS 80 40.0 11 7.40 14.47 0.4 46.2

141

4.6 FIGURES

Minas Basin

Stewiacke River

Grand Pré

Figure 4-1. Minas Basin and Minas Passage (MP) study area. Striped Bass tag release sites, are indicated by black diamond icons. The western point is the Stewiacke River, NS and the eastern point is Grand Pré, NS. The rectangle indicates the position of the FORCE demonstration site. Circles indicate the position of VEMCO VR2w acoustic receivers placed in the lower intertidal zone to investigate movements of Atlantic Sturgeon (M. Stokesbury, Acadia University). Data from these receivers were made available for this study.

142

Figure 4-2. Compact SUBS streamlined mooring package utilized during 2010 deployments. Note that all instruments are housed within the floatation unit, and that the chain riser was shortened from 5m to 2m following 2009 range testing (see Chapter 3).

143

Figure 4-3. Overview of VEMCO VR2w acoustic receiver mooring positions within Minas Passage during 2010. A dense array of 10 moorings, with 150-200m spacing, was positioned around an OpenHydro turbine installed within the FORCE demonstration site (top panel). The linear array (bottom panel) of 12 receiver stations, spaced at 400m intervals, was deployed in collaboration with the Ocean Tracking Network (OTN). Note that Station FORCE-E5 and Station MPS-04 were never recovered.

144

Figure 4-4. Distribution of Striped Bass detections logged by receiver stations within the MPS array (top panel) and FORCE array (bottom panel) binned by hour of day in which they occurred. Data is pooled for all Striped Bass detected by all receiver stations at each array. Detections were found to not deviate significantly from a uniform distribution, with no mean resultant time indicated for either the MPS array (Rayleigh test, P > 0.001, 4 = 0.09, n = 2603) or FORCE array (Rayleigh test, P > 0.001, r = 0.17, n = 663).

145

Figure 4-5. Boxplot showing daily Striped Bass detection counts, by tidal range (m), for all stations within Minas Passage. The thick black horizontal band indicates the median number of detections; upper lines indicates the 75th percentile, lower lines the 25 th percentile, whiskers represent the maximum and minimum number of detections recorded, and open circles depict outliers. The number of detections days at each tidal range is shown at the top of the figure above each boxplot. Daily detection count was not significantly correlated with tidal range (Pearson’s Correlation, r = 0.127, p = 0.11).

146

Figure 4-6. Total number of Striped Bass detections recorded during June-November, 2010 in relation tidal stage and depth-averaged current speed, binned by 0.25 m/s intervals. Dark and light bars represent detections during the ebb (e) and flood (f) tidal stages, respectively.

Figure 4-7. Total number of Striped Bass detections recorded during June-November, 2010 in relation to receiver array and depth-averaged current speed, binned by 0.25 m/s intervals. Dark and light bars represent detections at the FORCE demonstration site and MPS receiver arrays, respectively.

147 ected battery life, November, 2010. Symbols indicate release dates, exp - ass duringass June

ected. . Daily detections of acoustically tagged Striped B 8 - Figure Figure 4 and array(s) individualwhere Striped Bass were det

148

Figure 4-9. Spatial distribution of detections within Minas Passage during June-November, 2010 for individual Striped Bass released from the Stewiacke River tagging site. Solid black circles indicate a receiver station (see Figure 4-3) detecting a Striped Bass. The size of each black circle is proportional to the number of detections logged. Numbers at the top of each plot identify the individual Striped Bass depicted by the panel.

149

Figure 4-10. Spatial distribution of detections within Minas Passage during June-November, 2010 for individual Striped Bass released from the Grande Pré tagging site. Solid black circles indicate a receiver station (see Figure 4-3) detecting a Striped Bass. The size of each black circle is proportional to the number of detections logged. Numbers at the top of each plot identify the individual Striped Bass depicted in the panel. Note that the scales of the proportional detection circles are different between the Stewiacke (Figure 4-9, above) and Grand Pré release groups.

150

Figure 4-11. Scatterplot indicating the association between detection depth (m, below surface) and total length (cm) of acoustically tagged Striped Bass detected within Minas Passage during June-November 2010. A moderate yet significant correlation (Pearson’s Correlation, r = 0.413, p < 0.001) was found between variables.

151

Figure 4-12. Scatterplot indicating the association between detection depth (m, below surface) and depth- averages current speed (m/s) at time of detection for acoustically tagged Striped Bass detected within the FORCE test site during June-November 2010. A moderate yet significant correlation (Pearson’s Correlation, r = 0.419, p = <0.001) was found between variables.

152

ray. thickThe on the The x-axis. mate mate cross passage depth MPS-04 MPS-04 notwas recovered. percentile, whiskers male Striped Bass tagged th ation within the MPS ar ne indicates the appoxi site. Note that Station cates thecates detections of percentile, and the lower the 25 th ed at each station indicated is at the top each box es indicates thees 75 of all Striped Bass detections at each receiver st h open circles depicting outliers. solid The red li hile hile the upper lin ates detectedates Striped Bass tagged at the Grand Pré ed from the Stewiacke River, the central panel indi stations (m, MWL). The number of detections record Summary boxplots indicating depth (m, from surface)

. 13 - Figure Figure 4 black horizontal band indicates the median depth, w represent the maximum and minimum depth values, wit contour occupied by receiver panelleft indicates detections of female bass tagg thefrom Stewiacke River, and the right panel indic

153

th panel indicates gged at the Grand Pre site. ecorded at each station is olid red horizontal providelines a percentile, and the thelower 25 th of detections r h receiver station within the FORCE demonstration s thes 75 bass tagged thefrom Stewiacke River, the central the right panel indicates detected Striped Bass ta th withvalues, open circles depict outliers. s The eceivers were deployed within the array. numberThe from from surface) of all Striped Bass detections at eac Stewiacke River, and es the es median depth, thewhile upper indicatelines axis. axis. The left panel indicates detections of female - -5 was not was -5 recovered. Summary boxplots indicating depth (m, . 14 - ile, ile, whiskers represent the andmaximum minimum dep Figure Figure 4 array.site thickThe black horizontal band indicat percent reference of the range of depth (m, MWL) in which r indicated at the top each onbox the x the detections of male Striped tagged Bass thefrom Note that Station E

154

Figure 4-15. Kernel density plots of detection depth (m, below surface) of Striped Bass detected on the MPS array, as influenced by tidal stage (Ebb = pink shading, Flood = blue shading). The top panel indicates the distribution of detection depths of Striped Bass tagged from the Stewiacke River site, while the bottom panel indicates the distribution of detection depths from Striped Bass tagged from the Grand Pré site.

155

Figure 4-16. Kernel density plots of detection depth (m, below surface) of Striped Bass detected on the FORCE array, as influenced by tidal stage (e = ebb, pink shading, f = flood, blue shading). The top panel indicates the distribution of detection depths recorded from Striped Bass tagged from the Stewiacke River site, while the bottom panel indicates the distribution of detection depths from Striped Bass tagged from the Grand Pré site.

156

Figure 4-17. Kernel density plots of detection depth (m, below surface) of Striped Bass detected within Minas Passage from the Stewiacke tagging site, for each sex (F = female, pink shading, M = male, blue shading). The top panel indicates the distribution of detection depths recorded from Striped Bass detected on the MPS array, while the bottom panel indicates the distribution of detection depths from Striped Bass recorded on the FORCE array.

157

Figure 4-18. Kernel density plots of detection depth (m, below surface) of Striped Bass by time of day (Day = pink shading, Night = blue shading). The top panel indicates the distribution of detection depths of Striped Bass at the MPS receiver array, while the bottom panel indicates the distribution of detection depths of Striped Bass at the FORCE receiver array.

158

4.7 APPENDIX

Appendix 4-A. Tag metadata of all transmitter implanted Striped Bass (N = 80) released during 2010. All Striped Bass were tagged with VEMCO V13P-1H model transmitters.

N TL (cm) Sex Tag SN Tag ID Release Date Release Location Lat Long 1 82.4 F 1089108 30170 5/10/2010 Stewiacke River, NS 45.1607 -63.3309 2 73.7 F 1089107 30171 5/10/2010 Stewiacke River, NS 45.1607 -63.3309 3 71.4 F 1089106 30172 5/10/2010 Stewiacke River, NS 45.1607 -63.3309 4 69.2 M 1089105 30173 5/10/2010 Stewiacke River, NS 45.1607 -63.3309 5 73.6 F 1089104 30174 5/10/2010 Stewiacke River, NS 45.1607 -63.3309 6 67.0 F 1089103 30175 5/10/2010 Stewiacke River, NS 45.1607 -63.3309 7 67.2 F 1089102 30164 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 8 81.7 F 1089113 30165 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 9 78.9 F 1089101 30166 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 10 72.0 M 1089097 30167 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 11 63.0 M 1089111 30168 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 12 73.9 F 1089098 30169 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 13 77.8 M 1089099 30176 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 14 67.4 M 1089100 30177 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 15 69.0 M 1089112 30178 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 16 70.0 M 1089110 30179 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 17 76.8 F 1089109 34965 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 18 75.3 F 1089130 34978 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 19 66.5 M 1089126 34982 5/11/2010 Stewiacke River, NS 45.1607 -63.3309 20 76.2 F 1089127 34966 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 21 76.5 F 1089128 34967 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 22 63.7 F 1089129 34968 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 23 81.0 F 1089114 34969 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 24 68.3 M 1089115 34970 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 25 65.3 F 1089116 34971 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 26 71.6 F 1089117 34972 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 27 59.5 F 1089118 34973 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 28 79.0 F 1089119 34974 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 29 67.1 M 1089120 34975 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 30 64.4 M 1089121 34976 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 31 66.6 M 1089122 34977 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 32 73.9 F 1089123 34979 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 33 76.5 F 1089124 34980 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 34 77.7 F 1089125 34981 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 35 70.6 M 1089131 34983 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 36 68.9 M 1089132 34984 5/12/2010 Stewiacke River, NS 45.1607 -63.3309

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37 64.8 M 1089133 34985 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 38 66.0 M 1089134 34986 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 39 72.5 M 1089135 34987 5/12/2010 Stewiacke River, NS 45.1607 -63.3309 40 71.0 M 1089136 34988 5/13/2010 Stewiacke River, NS 45.1607 -63.3309 41 55.4 M 1089137 34989 5/13/2010 Stewiacke River, NS 45.1607 -63.3309 42 74.0 M 1089138 34990 5/13/2010 Stewiacke River, NS 45.1607 -63.3309 43 68.1 M 1089139 34991 5/13/2010 Stewiacke River, NS 45.1607 -63.3309 44 38.0 NA 1097685 3268 8/4/2010 Grand Pré, NS 45.1371 -64.2864 45 45.7 NA 1097686 3269 8/4/2010 Grand Pré, NS 45.1371 -64.2864 46 39.9 NA 1097688 3270 8/4/2010 Grand Pré, NS 45.1371 -64.2864 47 40.2 NA 1097687 3271 8/4/2010 Grand Pré, NS 45.1371 -64.2864 48 38.6 NA 1097689 3272 8/4/2010 Grand Pré, NS 45.1371 -64.2864 49 40.7 NA 1097690 3273 8/4/2010 Grand Pré, NS 45.1371 -64.2864 50 46.3 NA 1097691 3274 8/4/2010 Grand Pré, NS 45.1371 -64.2864 51 48.9 NA 1097684 3275 8/4/2010 Grand Pré, NS 45.1371 -64.2864 52 48.0 NA 1097692 3276 8/5/2010 Grand Pré, NS 45.1371 -64.2864 53 39.6 NA 1097693 3277 8/5/2010 Grand Pré, NS 45.1371 -64.2864 54 45.2 NA 1097694 3278 8/5/2010 Grand Pré, NS 45.1371 -64.2864 55 39.0 NA 1097695 3279 8/6/2010 Grand Pré, NS 45.1371 -64.2864 56 37.7 NA 1097696 3280 8/6/2010 Grand Pré, NS 45.1371 -64.2864 57 38.5 NA 1097697 3281 8/6/2010 Grand Pré, NS 45.1371 -64.2864 58 45.4 NA 1097698 3282 8/6/2010 Grand Pré, NS 45.1371 -64.2864 59 45.9 NA 1097699 3283 8/6/2010 Grand Pré, NS 45.1371 -64.2864 60 40.2 NA 1097700 3284 8/6/2010 Grand Pré, NS 45.1371 -64.2864 61 46.6 NA 1097701 3285 8/6/2010 Grand Pré, NS 45.1371 -64.2864 62 50.4 NA 1097702 3286 8/6/2010 Grand Pré, NS 45.1371 -64.2864 63 39.9 NA 1097703 3287 8/6/2010 Grand Pré, NS 45.1371 -64.2864 64 43.5 NA 1097704 3288 8/11/2010 Grand Pré, NS 45.1371 -64.2864 65 38.0 NA 1097706 3290 8/11/2010 Grand Pré, NS 45.1371 -64.2864 66 39.1 NA 1097707 3291 8/11/2010 Grand Pré, NS 45.1371 -64.2864 67 54.9 NA 1097708 3292 8/11/2010 Grand Pré, NS 45.1371 -64.2864 68 41.5 NA 1097709 3293 8/11/2010 Grand Pré, NS 45.1371 -64.2864 69 39.3 NA 1097710 3294 8/11/2010 Grand Pré, NS 45.1371 -64.2864 70 40.5 NA 1097711 3295 8/12/2010 Grand Pré, NS 45.1371 -64.2864 71 48.5 NA 1097713 3296 8/12/2010 Grand Pré, NS 45.1371 -64.2864 72 48.6 NA 1097714 3297 8/12/2010 Grand Pré, NS 45.1371 -64.2864 73 39.2 NA 1097715 3298 8/12/2010 Grand Pré, NS 45.1371 -64.2864 74 43.8 NA 1097716 3299 8/12/2010 Grand Pré, NS 45.1371 -64.2864 75 39.9 NA 1097717 3300 8/12/2010 Grand Pré, NS 45.1371 -64.2864 76 67.4 NA 1097718 3301 8/13/2010 Grand Pré, NS 45.1371 -64.2864 77 39.5 NA 1097719 3302 8/13/2010 Grand Pré, NS 45.1371 -64.2864

160

78 39.7 NA 1097720 3303 8/13/2010 Grand Pré, NS 45.1371 -64.2864 79 39.4 NA 1097721 3304 8/13/2010 Grand Pré, NS 45.1371 -64.2864 80 40.0 NA 1097712 3305 8/16/2010 Grand Pré, NS 45.1371 -64.2864

Appendix 4-B. Informational poster placed at common fishing locations as well as other areas that anglers frequent (post offices, gas stations, convenience stores, tackle shops, etc.) in communities throughout the study area. Posters outlined the tagging program, indicated the anatomical positioning and description of tags, and provided contact information to report recaptured fish or return transmitters.

161

Appendix 4-C. Depth-averaged current speed (m/s) frequency distributions, over a two month period, for each receiver station within the OTN-MPS array. Figures prepared by B. Sanderson.

162

163

CHAPTER 5 – General Discussion

Over the last 20 years, there has been limited direct study of the spatial and temporal use of Minas Basin by Striped Bass, and virtually no information on Striped

Bass use of the Minas Passage. Research described in this thesis was undertaken in an iterative manner to further inform the marine phase of the Striped Bass life cycle within the BoF system. Primary objectives were to: 1) examine recreational angling activity while characterizing Striped Bass angled from Minas Basin at Grand Pré, NS, and 2) test the efficacy of using VEMCO acoustic telemetry technology to track fish movements in the high flows of Minas Passage, and 3) investigate temporal and spatial presence, including depth distribution, of acoustically tagged Striped Bass within the Minas

Passage and in close proximity to the FORCE TISEC device demonstration site.

Collectively, this thesis research contributed data that helps address important knowledge gaps relating to Striped Bass use of the inner Bay of Fundy, and provides information that is of value to fishers, fishery managers, regulators, and industry proponents considering development opportunities within the Minas Passage and

Minas Basin, NS.

5.1 FINDINGS AND IMPLICATIONS

Creel survey and mark-recapture methods were used to examine population characteristics and near-shore presence of angled Striped Bass from within Minas Basin

(Chapter 2). Results of this three year survey of the Grand Pré intertidal recreational fishery indicated limited near-shore capture of Striped Bass of retainable size (≥68cm

TL), and high rates of catch and release for bass of non-retainable size. Bass angled from

164 the intertidal zone were dominated by 3-4yr olds, representing 75% of the total catch.

Over 80% of recaptures, which are known to be under-reported, were from the site of initial tagging at Grand Pré. Recapture results indicated patterns of within-season site residency and inter-annual site fidelity, suggesting a limited movement range of sub- adult Striped Bass during summer and early fall. Multiple recaptures included individual bass recaptured up to six times. Three recaptures were reported outside of Minas Basin, but within the BoF system, indicating travel through Minas Passage.

This and other conventional tagging studies (Rulifson et al., 2008; Bradford et al.,

2012) have been unable to resolve the temporal and spatial presence of Striped Bass within Minas Passage due to dependence on fishery recaptures and lack of a reporting fishery within Minas Passage. To address this issue, acoustic animal tracking technology was adopted for gathering data on fish movements in Minas Passage, including at the

FORCE turbine test site. The detection range and efficiency of VEMCO acoustic telemetry equipment was tested under tidally dominated, high-flow conditions in Minas

Passage (Chapter 3). As expected, detection of all tag models was negatively influenced by tidal currents, thus limiting detection range and overall efficiency. Detection efficiency was found to decrease to near zero during peak current flow periods, with successful detection being focused around periods of reduced current speed near slack water. In general, higher power tag models achieved better overall detection efficiency and transmission range. A detection efficiency model indicated that the maximal model, including all factors (current speed, tidal direction, tag power, and distance) and their interactions, was the best fit of the data. The model predicted distinct differences in

165 detection efficiency between ebb and flood tidal stages. These range and performance test results serve as the foundation for future animal tracking studies in Minas Passage and will be valuable to researchers working in other tidally dominated, high current sites.

Significant advances made during this study include the design and development of instrument moorings to withstand high current conditions in Minas Passage. A mooring design incorporating sub-surface, streamlined, floatation demonstrated limited movement throughout the 1.5 month deployment and a high rate of recovery. The basic mooring design described in Chapter 3 was also used for the Striped Bass tracking study described in Chapter 4, with minor modifications that allowed acoustic instruments to be housed within the SUBS unit. This advanced design performed well, surviving a deployment period of approximately 6 months in Minas Passage. Similar mooring designs have since been applied to other global OTN project deployments in high flow sites (e.g. the Strait of Gibraltar, Spain and Morocco; the Bass Straits, Australia).

Our investigation of acoustically tagged Striped Bass provides the first records demonstrating patterns in the temporal and spatial presence and swimming depths of

Striped Bass in Minas Passage and in close proximity to TISEC infrastructure (Chapter 4).

Acoustic telemetry methods were used to successfully detect striped bass within Minas

Passage and provided data of much higher resolution than conventional tagging.

Results of conventional tagging (Chapter 2) indicated that Striped Bass of small body size (<55cm TL) exhibit site residency within Minas Basin. Individuals of larger body

166 size (>55cm TL) were captured infrequently near-shore, indicating a dispersive movement pattern. The general trends observed with conventional tagging were further supported and informed by acoustic tracking of Striped Bass. Interestingly, of the 80 striped bass tagged, 26 were detected only within Minas Basin at near-shore receiver locations. Fifty-three acoustically tagged Striped Bass were detected within Minas

Passage throughout the summer-fall monitoring period, demonstrating that Striped Bass frequent this high flow area for purposes other than migration. Individual Striped Bass were detected in Minas Passage on up to 17% of available detection days. Striped Bass tagged from the Stewiacke River (assumed to be of SR origin) were of larger body size than those tagged from Grand Pré (aggregate population, origin unknown but likely SR), and exhibited greater use of Minas Passage, comprising 77% of all individuals detected.

Bass released from the Stewiacke River site were also found to utilize a broad range of depths (surface to >95m) within Minas Passage. Smaller bass tagged from Grand Pré exhibited activity primarily within Minas Basin, and were present throughout the summer-fall monitoring period. Grand Pré bass presence within Minas Passage was infrequent, and largely limited to the upper 10m of the water column. Given performance limitations of acoustic telemetry equipment outlined in Chapter 3, data presented from striped bass acoustic tracking are considered underestimates of actual movements near receiver locations in Minas Passage.

Site residency and site fidelity patterns of Striped Bass identified by the conventional tagging study and further supported by acoustic telemetry methods have implications for critical habitat designation (COSEWIC, 2012; DFO, 2014). Continued

167 examination of important habitat areas and how they overlap with potential impacts

(i.e. recreational angling, commercial fishing, and other anthropogenic activities) is warranted.

5.2 RECOMMENDATIONS

The present study has provided an important first investigation of Striped Bass activity in Minas Basin and Minas Passage, and contributes to the understanding of the

Striped Bass marine distribution and the recreational fishery in Minas Basin. However, several information gaps remain and should be considered for further study.

1) To limit spatial bias, any conventional tagging within Minas Basin should include

multiple tagging sites and/or involve tagging bass from known aggregation areas

such as Shubenacadie River-Grand Lake (overwintering site) or Stewiacke River

(spawning grounds) for examination of dispersal within Minas Basin/Minas

Passage.

2) Any future conventional tagging should be conducted as part of a directed mark-

recapture study to obtain estimates of abundance, growth, and mortality

parameters that are of importance to fisheries managers. Tagging and recapture

activities should be conducted as separate efforts rather than concurrently, and

should incorporate the ability to determine tag retention (through double

tagging), and tag return rate (using high reward tags) to permit more robust

estimates. It is important that estimates of population abundance be obtained

routinely with the goal of developing a reliable time series of data which can be

168

used to evaluate management changes, or any environmental or anthropogenic

impacts, in the context of inter-annual variability. This may require use of

alternative methodologies or combinations of methods to ensure reliability.

3) Determination of the exploitation level of local Striped Bass stocks through

recreational angling, First Nations food, social, and ceremonial (FSC) fisheries,

and by-catch fisheries is required to move forward with stock assessment and

monitoring of potential anthropogenic impacts. A method to monitor the

number of anglers participating in the recreational fishery and their retention

levels should be considered. Without knowledge of the various components of

mortality, and the level of inter-annual variability, our ability to determine

population level impacts due to anthropogenic effects will be limited.

4) Continued collection of egg production (MacInnis, 2012) and juvenile abundance

data (Bradford et al., 2012) should be encouraged and further effort made to link

this data to adult population demographics and overall abundance.

Incorporation of multiple data types may enhance the prediction of year class

success, allowing adaptive management of recreational angling and providing

early warning signs to monitor potentially negative anthropogenic impacts.

5) To better understand Striped Bass movements and occupancy within the Minas

Basin and Minas Passage further acoustic tracking is recommended. Subsequent

studies should use long life (multi-year) tags, and include year-round monitoring

over multiple successive years to examine both seasonal and inter-annual

variability in movement patterns of individuals. Results of this research have

169

served to inform a multi-year study in which an additional 85 striped bass were

tagged (Keyser, 2013; Redden et al., 2014). It is recommended that acoustic

detection data from all striped bass (N=165) be compiled for development of

predictive models of turbine encounter, evasion and collision risk probability.

6) Although suspected, this study was not designed to confirm that the range of

bass tagged from the SR (of assumed local origin) extends beyond Minas

Passage. Continuation of collaborative linkages with the Ocean Tracking Network

(OTN) and researchers who deploy similar acoustic tracking technology will

enhance the possibility of obtaining long range detections outside of an

immediate study area.

7) The use of acoustic telemetry provides options for examination of other aspects

of Striped Bass life history in addition to movement/migration. As suggested

previously, use of long-life, multi-year transmitters allow information to be

collected from individual bass over multiple seasons, permitting investigation of

mortality/survival, spawning activity, and seasonal habitat occupancy, including

overwintering areas. Concurrent acoustic monitoring of Minas Passage, Minas

Basin, and the Shubenacadie-Stewiacke River system (including Shubenacadie-

Grand Lake) would provide significant advancements in our understanding of

local stock specific patterns, overwintering habitat, contingent formation, etc.

8) Limitations of acoustic telemetry under high current speed prevent examination

of Striped Bass movements during portions of the tidal cycle expected to present

the greatest risk potential for Striped Bass interaction with TISEC device

170

infrastructure. It is unknown if bass are present and not detected, or absent

(selecting low flow areas elsewhere) during high flow periods. Modification or

further refinement of current acoustic telemetry methods, and/or use of

alternative methodologies to examine Striped Bass activity during high flow

periods should be considered.

9) While VEMCO acoustic telemetry technology has provided data on the presence

of Striped Bass within Minas Passage at mid- to far-field scales, it cannot be used

to examine near field (<10m) interaction of Striped Bass with TISEC

infrastructure. It is recommended that alternative acoustic techniques (i.e. active

acoustic sonar, acoustic cameras) and integrated sensor platforms be considered

in the examination of potential near-field interactions.

171

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