Temporal and Spatial Movement Patterns of Striped Bass in the Minas Passage, Bay of Fundy

TEMPORAL AND SPATIAL MOVEMENT PATTERNS OF STRIPED BASS IN THE MINAS PASSAGE, BAY OF FUNDY

Freya M. Keyser

Thesis submitted in partial fulfillment of the

requirements for the Degree of

Bachelor of Science with

Honours in Biology

Acadia University

April, 2013

This thesis by Freya M. Keyser

is accepted in its present form by the

Department of Biology

as satisfying the requirements for the degree of

Bachelor of Science with Honours

Approved by the Thesis Supervisor

______Dr. Anna Redden Date

Approved by the Head of the Department

______Dr. Soren Bondrup-Nielsen Date

Approved by the Honours Committee

______Dr. Pritam Ranjan Date

I, Freya Keyser, 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 in my thesis.

______Signature of Author

______Date

iii ACKNOWLEDGEMENTS

I would not have been able to complete this project successfully without the support of many groups and individuals. First and foremost, I must thank my supervisor

Dr. Anna Redden. I am very grateful that she welcomed me into her research program, and for her unwavering support throughout this endeavour. Thanks are also due to Acadia

University, the Offshore Energy Research Association of Nova Scotia (OERANS), the

Fundy Ocean Research Centre for Energy (FORCE), the Acadia Centre for Estuarine

Research (ACER) and the Ocean Tracking Network (OTN) for providing funding and research support to this project.

I thank Jeremy Broome not only for sharing part of his Masters project with me, but also for assisting with data analysis, sharing articles, leading fieldwork, proofreading, and for his patience in answering my endless questions. Additional fieldwork assistance for this project was provided by members of the Striped Bass Anglers Association of

Nova Scotia (SBAANS), the late Croyden Wood Jr. and his crew, Duncan Bates and

Stephane Kirchoff (OTN), and Colin Buhariwalla and Matthew Baker (ACER). I also thank Dr. Richard Karsten for providing modelled current speed estimates that were used in my analysis of data.

Another thank-you goes to my labmates for their support: Pete, Kaycee, Matthew and Jeremy. In addition to sharing R codes and fieldwork tips, they also provided encouragement, advice, and laughter along the way. I am lucky to have found myself in such good company! Finally, I would like to thank my family and friends for letting me talk about my thesis way too much, and for their unconditional support.

TABLE OF CONTENTS ACKNOWLEDGEMENTS ...... IV! LIST OF TABLES...... VI! LIST OF FIGURES...... VII! ABSTRACT ...... IX! 1.0 INTRODUCTION ...... 1! 1.1 MIGRATORY FISH ...... 1! 1.2 TIDAL POWER DEVELOPMENTS AND IMPACTS ON FISH ...... 3! 1.3 ASSESSING POTENTIAL RISK OF FISH-TURBINE INTERACTION ...... 5! 1.4 USE OF ACOUSTIC TELEMETRY TO MONITOR FISH MOVEMENTS...... 6! 1.5 RISK TO STRIPED BASS (MORONE SAXATILIS)...... 8! 1.6 STUDY OBJECTIVES ...... 10! 2.0 SITE DESCRIPTION AND METHODOLOGY...... 12! 2.1 SITE DESCRIPTION: THE MINAS PASSAGE...... 12! 2.2 ACOUSTIC RECEIVER LOCATIONS AND MOORINGS...... 14! 2.3 ACOUSTIC TRANSMITTERS ...... 17! 2.4 FISH TAGGING ...... 18! 2.5 DATA ANALYSIS...... 19! 2.6 LIMITATIONS OF ACOUSTIC TELEMETRY IN THE MINAS PASSAGE ...... 20! 3.0 RESULTS...... 23! 3.1 OVERVIEW OF DETECTIONS...... 23! 3.2 MOVEMENT THROUGH THE MINAS PASSAGE (CROSSINGS) ...... 24! 3.3 TEMPORAL AND SPATIAL MOVEMENT PATTERNS...... 25! 3.4 DETECTION DEPTHS ...... 39! 4.0 DISCUSSION...... 43! 4.1 SIZE-RELATED ACTIVITY OF STRIPED BASS...... 43! 4.2 EFFECTS OF DIURNAL, TIDAL, AND LUNAR CYCLES ON MOVEMENTS ...... 43! 4.3 SEASONAL TIMING OF MIGRATIONS...... 45! 4.4 SWIMMING SPEEDS...... 46! 4.5 SWIMMING DEPTH PATTERNS ...... 47! 4.6 CONCLUSIONS BASED ON VEMCO ACOUSTIC TELEMETRY...... 47! 4.7 RECOMMENDATIONS FOR FURTHER RESEARCH ...... 49! REFERENCES ...... 50! APPENDIX A...... 55!

LIST OF TABLES

Table 1. Minas Passage acoustic receiver deployment and recovery information from 2011. Receivers were numbered based on their location in the Minas Passage, from north to south. Receivers were recovered one of three ways: during a recovery mission (“R”), found floating by fishers (“F”) or washed-up on shore (“W”)...... 17! Table 2. Summary of striped bass tagged in 2011. Sizes were measured as fork lengths. Ages were calculated based on size using the equation y = 5.1622x + 18.865, where x and y were age (in year) and fork length (in centimeters), respectively (Jeremy Broome, unpublished data). Mean ages of Stewiacke and Grand Pré fish, at the time of tagging, were 10 ± 1 year and 5 ± 1 year, respectively...... 19! Table 3. Summary data and number of individual adult ("Stewiacke") and sub-adult ("Grand Pré") fish detected between June and December of 2011, in the Minas Passage...... 23! Table 4. Number of detections per month ("J, J, A, S, O, N" = June, July, August, September, October, and November, respectively) and total for adult (Stewiacke) and sub-adult (Grand Pré) fish at each array ("A" = Acadia University Line, "F" = FORCE line, "M" = Minas Passage Line)...... 24! Table 5. Number of fish detected per month (“J, J, A, S, O, N” = June, July, August, September, October and November, respectively) and total for adult (Stewiacke) and sub-adult (Grand Pré) fish, at each array (“AUL” = Acadia University Line; “FORCE” = FORCE line; “MPS” = Minas Passage Line)...... 24! Table 6. Data summary of fish crossings for the Minas Passage. A crossing was identified by two consecutive detections on either side of the passage. Standard deviations are shown for each average current speed (m/s) and average swimming speed (m/s, Body Length/s)...... 25! Table 7. Data summary of direct fish crossings (t ! 60 minutes) in the Minas Passage. A crossing was identified by two consecutive detections on either side of the passage. Standard deviations are shown for each average time (minutes) and body size (fork length in metres)...... 25! Table 8. Kruskal-Wallis tests and 2 sample, unpooled t-tests were performed to identify significant differences between the number of detections per hour that occurred during the day (“D”) and during the night (“N”), and the number of crossings per hour...... 27! Table 9. A Kruskal-Wallis test and 2 sample, unpooled t-test was performed on the number of detections of Stewiacke fish that occurred during ebb tides (“E”) vs. flood tides (“F”) in June, July and August. A Kruskal-Wallis test and Tukey test was performed on the number of detections per day within different tidal range categories, for Stewiacke fish in June, July and August. The tidal range categories were: 7.00-9.50 m (“A”), 9.51-11.50 m (“B”), and 11.51-14.00 m (“C”)...... 29!

LIST OF FIGURES

Figure 1. Map of Nova Scotia with inset map of the upper Bay of Fundy. The Minas Passage connects Minas Channel to Minas Basin, and is approximately 5 km wide. The FORCE turbine test site is located in the Passage, as indicated by the small red rectangle...... 12! Figure 2. Map of the northern Minas Passage showing the FORCE turbine test site, northern shore features, and Black Rock. The four turbine berths are labelled A-D, in yellow...... 14! Figure 3. Map of the Minas Passage showing deployment locations of acoustic receivers. Red points represent the “AUL” (Acadia University Line) receivers located on the western side of the passage and blue points represent the “MPS” (Minas Passage Line) receivers on the eastern side. Green points indicate the “AUL-T” receivers located in the FORCE test site (yellow rectangle). Receivers that were never recovered are indicated by a white “X”...... 15! Figure 4. a) Acoustic receiver mooring unit design (not to scale, adapted from Stokesbury et al., 2012). Interior of SUB buoy shown; when deployed, receiver and acoustic release are mounted within the SUB buoy. b) VR2W-69 kHz acoustic receiver (VEMCO, 2011). c) V13P-1H acoustic transmitter (VEMCO, 2011)...... 16! Figure 5. Striped bass were tagged at Grand Pré and the Stewiacke River in May and June, respectively...... 19! Figure 6. Number of detections per hour of day (AST) for all tagged fish during the June - November 2011 detection period. Bars are shaded by day (red) and night (blue). The total number of detections was 2366...... 26! Figure 7. Number of fish crossings per hour of day (AST) during the June - November 2011 detection period. A crossing was identified by two consecutive detections on either side of the Minas Passage, within fewer than 60 minutes of each other. Bars are shaded by day (red) and night (blue). There was a total of 39 crossings that took 60 minutes or less to travel approximately 5 km...... 27! Figure 8. Fish tagged in Grand Pré and Stewiacke (respectively) were detected similarly during ebb tides (red bars) and flood tides (blue bars)...... 28! Figure 9. Scatterplot and linear regression of the number of detections per day for Stewiacke fish in June (red circles), July (green triangles) and August (blue squares) with daily tidal ranges between 7 and 13.5 m...... 29! Figure 10. Movements from July to November 2011 of each fish tagged at Grand Pré, based on receiver latitude and longitude. Each plot is a different fish; tag ID number is indicated above each plot, along with “G” for Grand Pré, “S-A” for sub-adult, and respective fork lengths (in centimetres). Circles represent receiver stations where the transmitter was detected, lines show the order that the detections occurred...... 31! Figure 11. Movements from July to November 2011 of each fish tagged in the Stewiacke River, based on receiver latitude and longitude. Each plot is a different fish; tag ID number is indicated above each plot, along with “S” for Stewiacke, “A” for adult, and respective fork lengths (in centimetres). Circles represent receiver stations where the transmitter was detected, lines show the order that the detections occurred...... 32!

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Figure 12. Detections of transmitter 4987 (a highly active fish) during the month of July 2011, based on receiver latitude and longitude. Circles represent receiver stations where the transmitter was detected, lines show the order that the detections occurred. Each circle is numbered with the date(s) that detections occurred at that station. ....33! Figure 13. Individual fish movement between receiver lines over time. Each circle is a detection of a fish at the corresponding receiver line (“AUL” = Acadia line, “FORCE site” = FORCE test site, “MPS” = Minas Passage line). Lines between circles do not imply direct movements, just chronological order of detections. Tidal ranges (in metres) are shown on the right y-axis, in blue...... 34! Figure 14. Depths (in metres) at time of detection for fish tagged in Stewiacke (blue) and Grand Pré (in yellow) at each station in the AUL line (Minas Passage west). A bottom contour of the Minas Passage is shown in red, based on the depths of receivers in the water column (calculated from average water column depth). Sample sizes are shown above each boxplot...... 39! Figure 15. Depths (in metres) at time of detection for fish tagged in Stewiacke (blue) and Grand Pré (in yellow) at each station in the MPS line (Minas Passage east). A bottom contour of the Minas Passage is shown in red, based on the depths of receivers in the water column (calculated from average water column depth). Sample sizes are shown above each boxplot...... 40! Figure 16. Depths (in metres) at time of detection for fish tagged in Stewiacke (blue) and Grand Pré (in yellow) at each station in the FORCE line. A bottom contour of the Minas Passage is shown in red, based on the depths of receivers in the water column (calculated from average water column depth). Sample sizes are shown above each boxplot. The heights of the proposed tidal energy turbines will span up to 25 metres above the bottom, indicated by a black line...... 40! Figure 17. Boxplots of average crossing depths for Grand Pré (in red) and Stewiacke fish (in blue) during the June - November 2011 detection period. Sample sizes are shown above each boxplot...... 41! Figure 18. Scatterplot and regression of relationship between swimming depth (in metres) at time of detection and current speed (m/s) for all tagged fish at the FORCE site. Shading on each side of the regression line represents standard error...... 42!

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ABSTRACT

The Bay of Fundy’s Minas Passage (5-6 km wide) is currently the site for in- stream tidal energy turbine testing, but it is also a passageway for many commercially and recreationally important migratory fish species. Among these are striped bass

(Morone saxatilis), a recently listed endangered species. The objectives of this project were to determine the movement patterns of sub-adult and adult striped bass within the passage, and to assess the potential risk of interaction with tidal turbines. A total of 40 transmitter-tagged striped bass (20 adults and 20 sub-adults) were tracked using 29 bottom-moored VEMCO acoustic receivers. Two lines of receivers spanned the width of the Minas Passage and a third line spanned the turbine test area. All recovered receivers

(n=27) logged valid detections, with the highest number of detections occurring in July.

Of the 40 striped bass tagged, 25 were detected, with more adults detected (75%) than sub-adults (50%). Adult fish were detected at depths throughout the water column, while sub-adults were detected only in the top 25 m (above turbine height). Fifteen striped bass

(mostly adults) were shown to move back and forth through the passage at a mean swimming speed of 2.35 ± 0.71 m/s. Fish were detected more often at night than during the day. Detection frequency was higher during neap tidal cycles than during spring tidal cycles and was negatively correlated with current speed. Slightly more detections were during ebb tides than during flood tides. Unexpectedly, individual striped bass were shown to make multiple crossings of the Minas Passage during summer. In addition, many passed through the turbine test site at depths that include turbine hub height. The ability of striped bass to detect and avoid tidal turbines when travelling at high speed remains unknown.

1.0 INTRODUCTION

The Bay of Fundy’s Minas Passage is home to the marine renewable energy test centre, Fundy Ocean Research Centre for Energy (FORCE), which was established to test and assess the performance of large (1MW+) tidal in-stream energy conversion (TISEC) devices. Work is currently underway to determine the likelihood of turbine interactions with various marine biota, including fish that use the Minas Passage as a migratory route.

Given that large turbine structures and their operations pose a potential risk to fish populations in the Minas Passage, there is a need to understand how and when fish use the FORCE test site.

Acoustic telemetry is currently being used to monitor the use of the Minas

Passage and Basin by several potentially-at-risk species, including striped bass (Morone saxatilis). This thesis provides an analysis of the 2011 acoustic telemetry data on striped bass movements in the Minas Passage, and will inform the assessment of potential risk of fish-turbine interactions at the FORCE test site.

1.1 Migratory fish

In many fish species, the ability to migrate has been selected (Metcalfe et al.,

2002). The reasons why fish migrate vary; however, migrations are usually motivated by feeding or spawning requirements in concert with ever-changing environmental conditions (Metcalfe et al., 2002; Dingle and Drake, 2007).

While migration may seem the perfect answer to certain life history challenges, it also presents many obstacles. To follow a migration route, fish clearly must have some mechanism of navigation or orientation (Metcalfe et al., 2002). These mechanisms are not well understood at this time, but it is known that the strategies differ among species

(Metcalfe et al., 2002). Some studies provide evidence for olfaction as a navigation mechanism, but environmental factors also play a large role (Bertmar and Toft, 1969;

Khoo, 1974; Goff and Green, 1978; Binder and McDonald, 2007; Mitamura et al., 2012).

Varying light levels may affect the migratory behaviour of fish, suggesting that photoperiod acts as a signal to migrate (Leggett, 1997; Binder and McDonald, 2007;

Rulifson et al., 2008; Binder et al., 2011). Temperature is also important; certain fish species will postpone their migrations until a particular water temperature is achieved

(Leggett, 1997; Binder et al, 2011; Bradford et al., 2012). Correlations with weather events, currents, the earth’s electromagnetic field, and the lunar cycle have also been identified (Leggett, 1997; Breukelaar et al., 2009; Binder et al., 2011; Mitamura et al.,

2012).

Because fish rely on environmental cues to undergo migration, any anthropogenic activity in the aquatic environment has the potential to affect the migratory behaviour of fish. As human society continues to develop, migratory fish face an increasing number of barriers. The installation of hydroelectric or tidal power dams, turbines, and other underwater structures can physically block the migratory routes of fish, while also affecting variables like turbidity, current speed, and temperature (Lucas et al., 2001).

Another anthropogenic pressure is pollution, which can cause significant degradation to fish habitat (McDowall, 1988). Recreational and commercial fisheries introduce further challenges for fish. If a fishery is not carefully monitored and managed, and fish are prevented from spawning, a population can be extirpated very quickly (Evans and

Grainger, 2002).

Many Canadian migratory fish species and populations are assessed by

COSEWIC, the Committee on the Status of Endangered Wildlife in Canada. COSEWIC determines the status of animal species and populations found in Canada. Species that are not of concern are deemed “not at risk”, while species of increasing concern are identified as “special concern”, “threatened”, “endangered”, “extirpated” or “extinct”, respectively (COSEWIC, 2012a). These designations relate to Canada’s Species at Risk

Act (SARA), which aims to manage declining populations (COSEWIC, 2012a). Some examples of migratory fish that have been assessed by COSEWIC are American eel

(threatened), Atlantic salmon (extirpated in Lake Ontario, endangered elsewhere),

Atlantic bluefin tuna (endangered), porbeagle (endangered), and striped bass (endangered or special concern depending on the population) (COSEWIC, 2012b).

1.2 Tidal power developments and impacts on fish

One of the main anthropogenic pressures that migratory fish face is the blocking of their routes by physical barriers. Such barriers may be hydroelectric or tidal dams (also called barrages) containing turbines that extract energy from water currents or tides.

Dams provide sustainable, renewable energy, but they also present many challenges to fish populations in those areas. To make optimal use of the water flow, these barrages generally traverse a river, and contain one or more turbines under the surface. This means that migrating fish that swim down or upstream must somehow navigate safely to the other side of the dam; otherwise they can become trapped on one side.

Fish mortality due to the installation of a tidal barrage was studied at the tidal power generating station in Annapolis Royal, Nova Scotia (Stokesbury and Dadswell,

1991). The dam extends across the Annapolis River and contains a single, but large, 20

MW capacity Straflo turbine. To assist fish migrations into and out of the Annapolis

River, one fishway (a dam by-pass route) was initially constructed; however, after a study showed that only 0.2% of juvenile alosids were using that fishway (Stokesbury, 1986), a second fishway was constructed in a more suitable location. When only one fishway was available, juvenile alosid mortalities of 54% were observed (Stokesbury, 1986). The remaining fish managed to survive the passage either by using the fishway, or by somehow avoiding contact with the turbine blades. After the second fishway was installed, mortality decreased slightly; a tagging study showed that 46% of tagged fish

(juvenile clupeids) were killed by the turbine (Stokesbury and Dadswell, 1991).

Autopsies of the dead fish identified the following causes of death: mechanical strike, pressure change, shearing and cavitation (Dadswell et al., 1986; Stokesbury and

Dadswell, 1991). The term “mechanical strike” refers to the striking of fish by the rotating turbine blades (Dadswell et al., 1986). Increased water turbulence can force fish to unbearable depths, leading to internal pressure changes (Stokesbury and Dadswell,

1991). Shearing occurs when fish are caught between streams of water flowing in opposite directions, potentially causing damage to the gills or head (Dadswell et al.,

1986). The final injury type, cavitation, is due to the rapid release of vapor from cavities formed in the water; implosion results in strong forces and loud noises that can cause physical harm to fish (Jensen and Long, 1964).

The Dadswell and Stokesbury studies, however, only consider certain groups of fish. It is important to note that some sizes of fish could be more affected by a turbine than others. Smaller fish would have less trouble manoeuvring through a spinning turbine than a larger fish (like alosids and clupeids). Regardless, this could result in a long-term

change in size frequency within populations of larger fish, like striped bass. Clearly, effective dam by-passes are needed before hydroelectric dams can be deemed environmentally safe.

An approach to more sustainable tidal power generation is the design of stand- alone energy generating units. Currently, industry is attempting to do this through the development of in-stream tidal turbines, known as TISEC (tidal in-stream energy conversion) devices. These turbines are not located within dams and do not block off an entire passageway, thus minimizing the potential effects on biota and the environment in general. They have been used successfully at sites with moderate water flows but these findings may not be transferrable to high flow sites like the Minas Passage in the Bay of

Fundy. The Fundy Ocean Research Centre for Energy (FORCE) has recently developed a demonstration site in the Minas Passage near Parrsboro, Nova Scotia. At the FORCE site, a range of TISEC devices, cabled to shore, will be tested, commencing in 2015.

1.3 Assessing potential risk of fish-turbine interaction

Some of the same concerns raised for tidal barrage projects are being expressed for TISEC development projects, but because no dam or barrage is required, the number and magnitude of these concerns is reduced. Nevertheless, potential impacts must be identified and addressed prior to turbine installation and operation.

TISEC device operation could lead to changes in the movement patterns of fish in that area, due to fish avoidance of the turbines and changes in how water flows in the surrounding areas. This is especially pertinent in areas where migratory fish are present.

These fish rely on very specific migratory routes, and any changes or barriers to these routes could lead to population declines. Furthermore, fisheries depend on a longstanding

knowledge of migration patterns; should these patterns change, commercial fisheries may be negatively impacted. As with tidal barrages, direct contact with turbine blades is the major concern. Pre-installation environmental monitoring and research are needed to assess the risks to fish, however this in itself is challenging. At high flow sites, current speeds are so extreme that conventional research methods, including the use of fish nets and camera systems are not always possible. Currently, the most common way to monitor fish in high flow sites is to deploy hydroacoustic technology to track fish movements and behaviour.

1.4 Use of acoustic telemetry to monitor fish movements

Acoustic telemetry systems have been successfully used to track the movements of numerous species of migratory fish species (e.g. Lacroix and McCurdy, 1996; Cote et al., 2003; Welch et al., 2003; Lacroix et al., 2011). Telemetry systems consist of transmitters (electronic tags) and acoustic receivers. Transmitters are surgically implanted in fish, while acoustic receivers are deployed in fixed locations at the study site. The transmitters produce sequences of high frequency sounds (“pings”) at a set rate, and these sequences are recorded by the receivers when the transmitter is in close range. Each transmitter’s sequence is unique, allowing fish to be individually identified when receiver data are analysed. Some typical goals of acoustic telemetry are tracking movement, estimating population size, and understanding habitat use (Heupel et al., 2006). VEMCO acoustic telemetry is currently being used to track movements of tagged fish near the

Minas Passage tidal power demonstration site, with the aim of assessing potential impacts of turbine operation on species of concern.

6 Field experience has shown that the arrangement of the acoustic receivers must be carefully matched to the objectives of the study (Heupel et al., 2006; Broome and

Redden, 2012). Furthermore, meeting study objectives can be particularly challenging in high flow environments because of many uncontrollable variables. This challenge can be minimized through careful study design (Heupel et al., 2006). To examine movement patterns and migration, a “gate” and/or “curtain” set-up is recommended (Heupel et al.,

2006). In these formats, receivers are placed in lines across the study site to track fish as they enter and leave the site. In theory, placing receivers close enough to each other so that their detection ranges overlap ensures that all of the fish that enter or leave the study site are detected. This being said, it is crucial that the detection range of the receivers is tested in the environment of use. In fast flowing waters, like those at tidal turbine test sites, detection range varies with current speed and tag size parameters, so testing receiver range under high flows, prior to sensor array design and deployment, is necessary (Broome and Redden, 2012).

Acoustic telemetry studies in the Minas Passage have focused on species of concern - striped bass (Morone saxatilis), Atlantic sturgeon (Acipenser oxyrinchus) and

American eel (Anguilla rostrata). During 2010-2012, a number of these fish have been implanted with transmitters, and receivers have been deployed in strategic locations throughout the Minas Basin and Passage. So far, it has been determined that acoustic telemetry is effective in tracking the movements of these species near the turbine test site, and that these populations are indeed potentially at risk of interaction with turbines

(Stokesbury et al., 2012). However, as of yet, little is known about the movement patterns of these species in the vicinity of tidal turbines.

7 1.5 Risk to striped bass (Morone saxatilis)

Striped bass are anadromous fish (spawn in freshwater and migrate to sea to feed and grow), and belong to the perciformes order. They have a spiny dorsal fin, fusiform body, and general perch-like appearance (Scott and Scott, 1988; Bradford, et al., 2012).

COSEWIC has identified three “designatable units” of striped bass in Canada, defined by the discreteness and evolutionary significance of each population (COSEWIC, 2012a).

The Bay of Fundy population constitutes one of the three units, while the other two units are the Southern Gulf of St. Lawrence population and the St. Lawrence Estuary population. Currently, the St. Lawrence Estuary and Bay of Fundy units have been deemed endangered by COSEWIC (2012a), indicating that those units are facing imminent extirpation. The Southern Gulf of St. Lawrence population is listed under

“special concern”, meaning that potential problems have been identified and that this population could become threatened or endangered (COSEWIC, 2012a). The COSEWIC assessment has identified overfishing as the main overall threat to Canada’s striped bass populations, but pollution, changes to water flow and/or depth, and changes to spawning habitat are also issues. In the past, the endangered Bay of Fundy unit spawned in the

Shubenacadie, Saint John and Annapolis Rivers; however, as of the November 2012

COSEWIC assessment, spawning has been evident only in the Shubenacadie River

(COSEWIC, 2012a). Previous studies in the Bay of Fundy have shown that some striped bass tagged in the Minas Basin and Cobequid Bay migrate to the east coast of the United

States to spawn, indicating that the Bay of Fundy population contains both Canadian and

American stocks (Rulifson et al., 2008). The freshwater migration into the Shubenacadie

River occurs during the spring or early summer (McDowall, 1988), with adults returning

to the Bay of Fundy and out to the Atlantic Ocean in mid to late summer (Rulifson and

Tull, 1999; Lucas et al., 2001). Due to the high flow conditions in the Minas Passage, it is expected that striped bass swim directly through the passage during their outward migration.

Bay of Fundy striped bass spawning occurs mainly in the Stewiacke River tributary of the Shubenacadie River and begins once the water temperature is 18°C

(Rulifson and Tull, 1999). Most spawning occurs during neap tides, when there is clearer water and relatively constant salinity and temperature (Rulifson and Tull, 1999). Neap tides are tides in which the difference between high and low tide levels are the least. They occur twice a month when the Sun and Moon are at right angles to the Earth (total gravitational pull on ocean water is weakened). The largest tidal ranges, and highest current speeds during ebb and flood tides, occur on the spring tides.

It is believed that the Saint John River and Annapolis River striped bass populations have been extirpated due to human exploitation and other anthropogenic impacts on habitat (COSEWIC, 2012a). Overfishing has occurred to some extent; too many striped bass have been caught in the past, largely due to poaching and by-catch

(COSEWIC, 2012a). In the Annapolis River, some possible explanations for the disappearance are a lowered pH level reducing the successful hatching of eggs, agricultural run-off and changes to circulation in the estuary (Bradford et al., 2012). The circulation changes were largely attributed to the 1960s construction of a causeway across the river and the 1984 installation and operation of the Annapolis Royal tidal generating station (Bradford et al., 2012; COSEWIC, 2012a). In the Saint John River, it is suspected that both by-catch and recreational angling have contributed to the downfall

of the striped bass population, but this cannot be confirmed (Bradford et al., 2012;

COSEWIC, 2012a). It also appears that spawning in the Saint John River was greatly reduced by the construction of a hydroelectric dam and the consequent habitat changes that occurred (Bradford et al., 2012; COSEWIC, 2012a).

Understanding the effects that TISEC devices could have on other fish species, including prey species, is important to the maintenance of the Bay of Fundy striped bass.

Striped bass are carnivorous fish, taking advantage of feeding opportunities whenever possible (Scott and Scott, 1988). Their diets differ depending on life stage; larvae feed mainly on zooplankton, and juveniles on small crustaceans, annelid worms, and insects; adult striped bass have been known to feed on alewives, herring, smelt, eels, flounders, mummichogs, rock gunnels, sand lance, silver hake, silversides, shad and some invertebrates (Scott and Scott, 1988). If any of the main prey populations are reduced by the installation and/or operation of TISEC devices in the Minas Passage, the resulting lack of food could affect the striped bass population, especially the juveniles, which may be eaten by Atlantic tomcod, Atlantic cod, silver hake, or even adult striped bass (Scott and Scott, 1988).

1.6 Study objectives

Striped bass populations have been negatively affected by human activities, including the installation of a turbine in the causeway at Annapolis Royal, Nova Scotia.

The purpose of this study is to determine if striped bass in the Minas Passage could be at risk during the testing of stand-alone TISEC devices and arrays. The study uses acoustic telemetry data collected by receivers positioned across the Minas Passage. The main objectives of this study are to:

1. Determine temporal and spatial movement patterns of tagged adult and sub-adult

striped bass in the Minas Passage with respect to tidal conditions (tidal range,

flood and ebb tide, and current speed); and

2. Assess the potential risk of striped bass encounter with tidal energy infrastructure,

based on movement patterns observed (objective 1).

2.0 SITE DESCRIPTION AND METHODOLOGY

2.1 Site description: the Minas Passage

The Bay of Fundy is located between the southern coast of New Brunswick and the west coast of Nova Scotia (Figure 1). It is split by Cape Chignecto into two smaller channels; the southern branch begins with the Minas Channel, which runs through the

Minas Passage into the Minas Basin. The innermost part of the basin is Cobequid Bay, which is fed by the Shubenacadie River. The Avon River is the other major tributary of the Minas Basin.

The Bay of Fundy is famous for having the highest tides in the world, which occur due to the wave resonance in the bay (Hasegawa et al., 2011; Oceans Ltd., 2009).

The oscillation period of waves in the bay matches the Atlantic semi-diurnal tide period, which results in very wide tidal ranges (Oceans Ltd., 2009). The Minas Passage is 5 to 6 kilometres wide, and when water is forced through this narrow passage every tidal cycle, current speeds can exceed 6 m/s, with depth-averaged speeds reaching 3.28 m/s (Karsten et al., 2008). These current speeds create the high flow environment that is of such great interest to the tidal power industry. The deepest part of the passage is approximately 115 metres, and the water column is well mixed due to the high current speeds and tides

(Fader, 2009). Water temperatures range from approximately 16°C in August to just below 0°C in February (Envirosphere, 2009).

Another important characteristic is the presence of Black Rock, located near the northern shore of the Minas Passage, west of Parrsboro (Fader, 2009, Figure 2). It is of interest due to its effects on flow and turbulence. Current speeds and flow directions near

Black Rock are less predictable than those in other areas of the Minas Passage.

Furthermore, the northern shore of the Minas Passage has numerous embayments, and greater complexity, than the mainly linear southern shore (Fader, 2009).

The combined effects of Black Rock and the variable northern shoreline result in less predictable water flows in the northern part of the Minas Passage and thus the

FORCE test site, which is located 1-2 km west of Black Rock (Figure 2). FORCE has selected four berths at the test facility where turbines will be installed and their performance examined (AECOM, 2011). The maximum size of the proposed designs is

30 m tall and 20 m wide (AECOM, 2011).

Figure 2. Map of the northern Minas Passage showing the FORCE turbine test site, northern shore features, and Black Rock. The four turbine berths are labelled A-D, in yellow.

2.2 Acoustic receiver locations and moorings

The acoustic telemetry system deployed in 2011 consisted of receivers and transmitters manufactured by VEMCO, a company based in Halifax, Nova Scotia. For this study, 29 VR2W-69 kHz single channel acoustic receivers were used to detect tagged fish (Figure 4). These receivers are capable of recording tag transmission sequences at 69 kHz. The receivers deployed in 2011 were placed in three lines in the Minas Passage

(Figure 3). Two of these lines, the “Acadia University Line” (“AUL”) and the “Minas

Passage Line” (“MPS”), transect the Minas Passage; the AUL array was located west of the FORCE site, and the MPS array was located east of the FORCE site (Table 1). The outer receiver lines were 4-5.5 km apart. The third AUL line was a short array of three

receivers located within the FORCE test area (Figure 3; Table 1). The AUL receivers

(including those deployed at the FORCE site) are owned and deployed by Acadia

University, while the MPS receivers are part of the Ocean Tracking Network’s monitoring program. All receivers were deployed on April 7 and 8, 2011.

Figure 3. Map of the Minas Passage showing deployment locations of acoustic receivers. Red points represent the “AUL” (Acadia University Line) receivers located on the western side of the passage and blue points represent the “MPS” (Minas Passage Line) receivers on the eastern side. Green points indicate the “AUL-T” receivers located in the FORCE test site (yellow rectangle). Receivers that were never recovered are indicated by a white “X”.

Receiver recovery was attempted on December 13, 2011. A Teledyne Benthos transducer was used to communicate with each acoustic release to signal the release of the SUB float from the riser chain, allowing the float to pop up to the surface. Due to issues with premature battery failure in many units, recovery was successful for only 14 of the 29 receiver stations (Table 1). Thirteen of the remaining receivers were later found washed up on shore or floating in the Minas Passage. Two of the 29 receivers were never

recovered (Table 1; Figure 3). It is possible that some detections on washed up or floating receivers occurred following release of an instrumented buoy from its mooring, but since very few tags were detected after November it is likely that all receivers remained in place until December 1, 2011.

The receiver mooring design that was used successfully in 2010 was replicated in

2011 (Stokesbury et al., 2012; Figure 4). In each mooring unit, the acoustic receiver was attached to a Teledyne Benthos 875-T acoustic release inside a modified A2 SUB float

(Open Seas Instrumentation). The SUB float provided the mooring unit with 35 kg of positive buoyancy, which ensured that the equipment would float in the water column.

Each mooring unit was anchored using four sections of heavy chain link (4-5 chain links per section), weighing approximately 200 kg in total. The SUB buoy was connected to the anchor by a two-metre riser chain.

a) b) c)

Figure 4. a) Acoustic receiver mooring unit design (not to scale, adapted from Stokesbury et al., 2012). Interior of SUB buoy shown; when deployed, receiver and acoustic release are mounted within the SUB buoy. b) VR2W-69 kHz acoustic receiver (VEMCO, 2011). c) V13P-1H acoustic transmitter (VEMCO, 2011).

2.3 Acoustic transmitters

The striped bass monitored in this study were tracked using VEMCO coded transmitters (V13P-1H) that produced ping sequences at 69 kHz (VEMCO, 2011; Figure

4). The transmitters have an estimated life of 170 days, measure 36 millimetres in length and 13 millimetres in diameter, and weigh 6 grams in water (VEMCO, 2011). The power output of the transmitters is 156 decibels (VEMCO, 2011). Each transmitter emits a unique ping sequence at a random time every 45-95 seconds. Since each transmitter’s sequence is unique, researchers are able to identify and track individual fish. In addition to the date, time and ID code of the transmission, each transmitter sequence also conveyed the depth of the transmitter at the time of the transmission.

2.4 Fish tagging

In 2011, a total of 40 striped bass were tagged, including 20 fish collected on the shore near Grand Pré, and 20 from the Stewiacke River (Figure 5). Tagging occurred on

May 24 and 25, 2011 in Stewiacke, and on June 25 and 26, 2011 in Grand Pré (Table 2).

The different tagging sites were selected to enable tagging of both adults and sub-adult striped bass. Fish tagged in the Stewiacke River, a well-known spawning location for striped bass, were post-spawners. Sub-adults were tagged at Grand Pré, which is located near the outflows of multiple rivers that flow into the Minas Basin.

Once a fish was caught (via angling), measurements of fork length (FL) and total body length (TL) were taken to assist in the discrimination between adults and sub-adults

(Table 2). Each fish was tagged externally using a 3” Blue T-Bar tag (Floy Tag Inc.).

Scales and a small clipping of the pelvic fin were collected for later DNA analysis. An acoustic transmitter was inserted in the ventral body cavity by Jeremy Broome, following a surgical procedure approved by Fisheries and Oceans Canada (DFO Scientific Permit

#322857), and Acadia University’s Weston Animal Care Facility.

Figure 5. Striped bass were tagged at Grand Pré and the Stewiacke River in May and June, respectively.

Table 2. Summary of striped bass tagged in 2011. Sizes were measured as fork lengths. Ages were calculated based on size using the equation y = 5.1622x + 18.865, where x and y were age (in year) and fork length (in centimeters), respectively (Jeremy Broome, unpublished data). Mean ages of Stewiacke and Grand Pré fish, at the time of tagging, were 10 ± 1 year and 5 ± 1 year, respectively. Tagging Latitude Longitude Tagging Growth Number Size Age site dates stage tagged range range (2011) (cm) (yrs) Stewiacke 45.16077 -63.33094 May 24 – Adult 20 63.3- 9-12 River 25 81.0 Grand Pré 45.13710 -64.28640 June 25 – Largely 20 38.2- 4-8 Beach 26 sub-adults 60.7

2.5 Data analysis

VEMCO’s VUE software was used to retrieve the data collected by the receivers.

This program enables users to download transmitter detection data to a computer to be analysed. The downloaded data was exported as a Microsoft Excel spreadsheet, processed for duplicate detections, and later imported to the R statistical package for data analysis. Data for tidal state, water depth, and current speed were obtained from Dr.

Richard Karsten (Acadia University).

Prior to addressing any of the questions being examined by this study, it was necessary to filter the detection data. The following filtering process is standard practice in the analysis of acoustic telemetry datasets and was recommended by VEMCO.

Filtering is necessary to account for the possibility of the same fish being detected by multiple receivers in the same area. For example, if fish “A” was detected by receiver “1” at 12:40:00, but was also detected by receiver “2” at 12:40:06, the second detection was not counted. Transmission sequences occur once every 45-95 seconds, so it is not possible that these were two separate transmissions coming from the same transmitter.

Clearly, the transmission was carried through the water and detected by multiple receivers. To account for this phenomenon, the data was manually filtered in Microsoft

Excel. It was decided that if a transmitter was detected by more than one receiver within

20 seconds of a prior detection for that same transmitter, the later transmission would be deleted. This helped to condense the data and ensured that each transmission was recorded only once. The 20-second time limit was chosen somewhat arbitrarily, but was conservative enough to account for the 45-95 second transmission sequence rate of the transmitters. While filtering through the data, every effort was made to ensure that only duplicate detections were deleted.

2.6 Limitations of acoustic telemetry in the Minas Passage

Acoustic telemetry has been used widely for many years, but does have weaknesses. The conclusions that can be drawn from this type of dataset are limited and many potential errors must be considered. Firstly, there is a chance that some of the transmissions recorded did not actually occur (the receivers could have recorded detections for non-transmitter sounds at the 69 kHz frequency), or that not all of the

transmissions within detection range were recorded. While it is highly unlikely that the receivers detected faulty transmissions (due to their highly specialized ping sequences), upon analyzing the detection data, it became clear that some transmissions must have been missed. For example, the first tag detection of a fish was expected to occur on the

MPS line (eastern side of the passage) given that the fish were tagged in the Minas Basin and Stewiacke River, but this was not always the case. Receivers can only record full transmissions, so if the receiver does not detect a complete ping sequence, then the transmission will be missed. It is likely that this occurred on a number of occasions.

It was assumed that all of the acoustic receivers behaved similarly, despite the location and depth of their mooring, and that the moorings did not move during the detection period. Similarly, it is known that the detection ranges of the receivers vary with changing current speeds due to the effects of currents on ambient noise levels. While the receiver arrays were designed with this in mind (positioned 200 m apart), it is possible that, at very high current speeds, transmissions within 200 m of the receivers were not detected because they were outside the high flow detection range.

Furthermore, the amount of information that can be extrapolated from the receiver data is limited. The data indicate that a particular fish was present at a certain depth near a receiver at the recorded time, but once the fish leaves the receiver range, it is impossible to know with certainty where it goes. Speculations about directionality and movement between the receiver arrays can be made, but these cannot be verified with complete confidence.

Regardless of the uncertainties in using acoustic telemetry to track fish movements in high flow environments, the data collected to date is informative, and

could not be gathered using any other study method (such as mark and recapture or tag returns). The telemetry dataset represents a minimum level of striped bass activity, and as such, any patterns or trends determined herein may, in fact, be stronger than suggested.

3.0 RESULTS

3.1 Overview of detections

Upon analysis of the data recorded by the receivers in 2011, it was found that

75% (n=15) of the Stewiacke fish tagged were detected, compared to 50% (n=10) of the

Grand Pré tagged fish (Table 3). Once duplicates were removed (as described above), the total number of detections was 2366. Stewiacke fish were detected by receivers far more often than Grand Pré fish (Table 3). Raw detection data is provided in Appendix B.

Table 3. Summary data and number of individual adult ("Stewiacke") and sub-adult ("Grand Pré") fish detected between June and December of 2011, in the Minas Passage. Tagging location Stewiacke Grand Pré Number of fish tagged 20 20 Number of tagged fish detected 15 10 Total number of detections 2170 196

Grand Pré fish were not tagged until late June, and therefore could not be detected during that month. Of the months that receivers were deployed, July had the most detections, and September the fewest (Table 4). The MPS (Minas Passage west) line

(n=12 receivers) had the highest number of detections overall (Table 4). The number of different fish detected per receiver line varied only slightly, despite the differences in number of detections per line (Table 5).

Table 4. Number of detections per month ("J, J, A, S, O, N" = June, July, August, September, October, and November, respectively) and total for adult (Stewiacke) and sub-adult (Grand Pré) fish at each array ("A" = Acadia University Line, "F" = FORCE line, "M" = Minas Passage Line). Tagging Array # of recovered Number of detections (by month and in total) site receivers J J A S O N Total Stewiacke A 13 217 390 147 15 21 15 761 F 2 30 79 28 1 11 2 151 M 12 374 490 166 9 84 91 1262 Grand Pré A 13 NA 33 22 62 5 0 122 F 2 NA 0 2 0 0 0 2 M 12 NA 39 16 0 15 2 72 TOTAL -- -- 621 1031 381 87 136 110 2366

Table 5. Number of fish detected per month (“J, J, A, S, O, N” = June, July, August, September, October and November, respectively) and total for adult (Stewiacke) and sub- adult (Grand Pré) fish, at each array (“AUL” = Acadia University Line; “FORCE” = FORCE line; “MPS” = Minas Passage Line). Tagging site Array # of recovered Number of individual fish detected (by receivers month and in total) J J A S O N Total Stewiacke A 13 6 10 7 3 4 2 14 F 2 3 9 3 1 1 2 12 M 11 6 11 8 2 6 1 15 Grand Pré A 13 NA 1 3 3 3 0 8 F 2 NA 0 1 0 0 0 1 M 11 NA 1 3 0 4 1 7

3.2 Movement through the Minas Passage (crossings)

The detection data identified 39 striped bass crossings (MPS – AUL; about 5 km) that occurred within 60 minutes or less (Table 6). These crossings were deemed “direct” crossings because it was assumed that fish would have had to swim straight through the passage in order to cross within one hour. Average current speeds when direct crossings occurred ranged from 0.3 m/s to 2.0 m/s. Swimming speeds of directly crossing fish ranged from 1.2 m/s to 3.6 m/s.

The greatest number of direct crossings occurred in July (Table 7). Striped bass spent an average of 36 minutes between east and west receiver lines, and tended to be larger in size than tagged bass that did not undergo direct crossings.

Table 6. Data summary of fish crossings for the Minas Passage. A crossing was identified by two consecutive detections on either side of the passage. Standard deviations are shown for each average current speed (m/s) and average swimming speed (m/s, Body Length/s). Crossing Number Average Average body Average Average time of current size (m) swimming swimming (minutes) crossings speed (m/s) speed (m/s) speed (BL/s) (0,10] 0 NA NA NA NA (10,20] 0 NA NA NA NA (20,30] 10 1.30 ± 0.47 0.73 ± 0.05 2.9 ± 0.3 4.0 ± 0.4 (30,40] 20 1.20 ± 0.51 0.67 ± 0.05 2.3 ± 0.3 3.4 ± 0.6 (40,50] 4 0.82 ± 0.35 0.71 ± 0.09 1.6 ± 0.2 2.2 ± 0.2 (50,60] 5 0.88 ± 0.53 0.69 ± 0.04 1.4 ± 0.2 2.0 ± 0.3 (0,60] 39 1.14 ± 0.50 0.69 ± 0.06 2.3 ± 0.6 3.3 ± 0.8

Table 7. Data summary of direct fish crossings (t ! 60 minutes) in the Minas Passage. A crossing was identified by two consecutive detections on either side of the passage. Standard deviations are shown for each average time (minutes) and body size (fork length in metres). Number of Number of Average time in Average body crossings different fish passage (minutes) size (m) June 10 5 33.2 ±7.6 0.71 ± 0.05 July 14 8 37.8 ± 9.9 0.68 ± 0.05 August 5 5 40.4 ± 11.3 0.68 ± 0.10 September 2 2 31.5 ± 7.8 0.77 ± 0.02 October 6 4 41.2 ± 6.3 0.67 ± 0.03 November 2 1 23.5 ± 3.5 0.73 Entire period 39 15 36.0 ± 9.3 0.70 ± 0.06

3.3 Temporal and spatial movement patterns

A diurnal pattern was observed, where fish were detected significantly more often during the hours prior to 08:00 (AST) and after 20:00 (AST); these hours were the estimated times of sunrise and sunset, respectively (Figure 6, Table 8). The number of

detections that occurred at night was 1509 (64% of all detections); daytime detections totalled 857 (36% of all detections).

Timing of direct fish crossings showed a similar trend (Figure 7). More direct crossings occurred at night (before 8:00 or after 20:00 AST) than during the day (26 crossings vs. 13 crossings, or 67% vs. 33% of all direct crossings). This tendency was statistically significant at p=0.10, but not at p=0.05 (Table 8).

Figure 6. Number of detections per hour of day (AST) for all tagged fish during the June - November 2011 detection period. Bars are shaded by day (red) and night (blue). The total number of detections was 2366.

Figure 7. Number of fish crossings per hour of day (AST) during the June - November 2011 detection period. A crossing was identified by two consecutive detections on either side of the Minas Passage, within fewer than 60 minutes of each other. Bars are shaded by day (red) and night (blue). There was a total of 39 crossings that took 60 minutes or less to travel approximately 5 km.

Table 8. Kruskal-Wallis tests and 2 sample, unpooled t-tests were performed to identify significant differences between the number of detections per hour that occurred during the day (“D”) and during the night (“N”), and the number of crossings per hour. Test P-value p = 0.10 p = 0.05 All detections Kruskal-Wallis 0.006 N>D N>D T-test 0.011 N>D N>D Crossings (!60 minutes) Kruskal-Wallis 0.079 N>D N=D T-test 0.088 N>D N=D

It was expected that the direction of the tide would have a strong effect on the number of detections logged by the receivers; however, this was not the case. Detection frequencies for Stewiacke-tagged fish were only slightly higher during ebb tides than for flood tides (Figure 8), but this difference was not statistically significant at p=0.05 or p=0.10 (Table 9).

Figure 8. Fish tagged in Grand Pré and Stewiacke (respectively) were detected similarly during ebb tides (red bars) and flood tides (blue bars).

In regards to the lunar cycle, it was found that the mean number of detections per day of Stewiacke fish in June, July and August, was greater during days with tidal ranges between 7 and 9.5 metres (Figure 9). This tendency was not statistically significant at p=0.05; however, it was significant at p=0.10 (Table 9).

Figure 9. Scatterplot and linear regression of the number of detections per day for Stewiacke fish in June (red circles), July (green triangles) and August (blue squares) with daily tidal ranges between 7 and 13.5 m.

Table 9. A Kruskal-Wallis test and 2 sample, unpooled t-test was performed on the number of detections of Stewiacke fish that occurred during ebb tides (“E”) vs. flood tides (“F”) in June, July and August. A Kruskal-Wallis test and Tukey test was performed on the number of detections per day within different tidal range categories, for Stewiacke fish in June, July and August. The tidal range categories were: 7.00-9.50 m (“A”), 9.51- 11.50 m (“B”), and 11.51-14.00 m (“C”). Test P-value p=0.10 p=0.05 Ebb vs. flood Kruskal-Wallis 0.827 E=F E=F T-test 0.684 E=F E=F Tidal range Kruskal-Wallis 0.097 A>B; A>C A=B=C categories Tukey 0.080 A>B; A>C A=B=C

Geolocations of receivers where fish were detected were plotted as a visual aid in understanding the movement of striped bass in the Minas Passage (Figures 10 and 11).

While it showed that many fish moved back and forth in the passage during the detection period, Stewiacke fish (post-spawning adults) appeared to be more active, and were

detected at a larger number of receivers (Figure 11) than Grand Pré fish (Figure 10).

Direct crossings occurred most frequently on the southern side of the passage (south of

AUL-07 to MPS-06, n=25). Six direct crossings occurred entirely on the northern side, 7 were diagonal movements (fish were detected on the northern and southern sides) and 3 occurred in the middle of the passage.

The July movements of one of the most active fish (transmitter ID 4987) were examined in greater detail (Figure 12). This fish was detected at 19 different receivers and had high numbers of both detections (n=234) and direct crossings (n=6). It was found that the detections of tagged fish 4987 tended to occur on one or two days each week (as opposed to detections throughout the week). Furthermore, it was observed that this fish crossed the passage multiple times on the 7th, 11th, 15th, and 31st of July 2011.

. adult, and and adult, - A” for sub - ed on receiver latitude and longitude and latitude on receiver ed , bas transmitter was detected, lines showorder lines the was detected, transmitter Circles represent receiver stations where the where stations receiver represent Circles

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detections the that showorder lines the was detected, tter

. Detections of transmitter 4987 (a highly active fish) during the month of July 2011, based on receiver latitude and and latitude of on receiver month fish)July 2011, based the during active highly 4987 (a of transmitter . Detections

12 Figure Figure transmi the where stations receiver represent Circles longitude. station. that at occurred detections that date(s) the with is numbered circle Each occurred.

The movements of 15 striped bass that crossed the passage in 100 minutes or less were plotted with respect to date, receiver line, and tidal range (Figure 13). It was found that crossings occurred mostly in June, July and August, usually during neap tides (tidal ranges ! 9 m). Eight of the fifteen striped bass shown here were detected late in the year

(October – December), usually on the eastern (Minas Basin) side of the passage.

Figure 13. Individual fish movement between receiver lines over time. Each circle is a detection of a fish at the corresponding receiver line (“AUL” = Acadia line, “FORCE site” = FORCE test site, “MPS” = Minas Passage line). Lines between circles do not imply direct movements, just chronological order of detections. Tidal ranges (in metres) are shown on the right y-axis, in blue.

Figure 13 continued. Individual fish movement between receiver lines over time. Each circle is a detection of a fish at the corresponding receiver line (“AUL” = Acadia line, “FORCE site” = FORCE test site, “MPS” = Minas Passage line). Lines between circles do not imply direct movements, just chronological order of detections. Tidal ranges (in metres) are shown on the right y-axis, in blue.

3.4 Detection depths

Pressure sensors in the tags allowed detection of swimming depth at the time of tag detection. Along the AUL line (Minas Passage west) and MPS line (Minas Passage east), Stewiacke fish were detected at a wider range of depths, and at deeper depths than

Grand Pré fish (Figures 14 and 15). The same pattern was observed at the FORCE site. It is noteworthy that the depths of Stewiacke fish (adults) overlapped with the expected turbine hub heights (Figure 16). In contrast, the Grand Pré fish were detected in the

FORCE test site at depths above expected turbine hub height (Figure 16).

Figure 14. Depths (in metres) at time of detection for fish tagged in Stewiacke (blue) and Grand Pré (in yellow) at each station in the AUL line (Minas Passage west). A bottom contour of the Minas Passage is shown in red, based on the depths of receivers in the water column (calculated from average water column depth). Sample sizes are shown above each boxplot.

Figure 15. Depths (in metres) at time of detection for fish tagged in Stewiacke (blue) and Grand Pré (in yellow) at each station in the MPS line (Minas Passage east). A bottom contour of the Minas Passage is shown in red, based on the depths of receivers in the water column (calculated from average water column depth). Sample sizes are shown above each boxplot.

Figure 16. Depths (in metres) at time of detection for fish tagged in Stewiacke (blue) and Grand Pré (in yellow) at each station in the FORCE line. A bottom contour of the Minas Passage is shown in red, based on the depths of receivers in the water column (calculated from average water column depth). Sample sizes are shown above each boxplot. The heights of the proposed tidal energy turbines will span up to 25 metres above the bottom, indicated by a black line.

Average depths of fish completing direct crossings were also calculated using the detection depths at the beginning and end of the crossing (and middle, if fish were detected at the FORCE site). It was found that fish undertaking direct crossings during the summer swam at various depths in the water column, but were more concentrated in near-surface waters during the months of October and November (Figure 17).

Figure 17. Boxplots of average crossing depths for Grand Pré (in red) and Stewiacke fish (in blue) during the June - November 2011 detection period. Sample sizes are shown above each boxplot.

A relationship between swimming depth and average water column current speed was also demonstrated. At high current speeds (average water column speed >1.3m/s) at the FORCE site, detected fish were usually deeper in the water column (>30 m below the surface; Figure 18). However, swimming depths were variable and detections occurred throughout the water column, at average current speeds up to 1.8 m/s (Figure 18).

Figure 18. Scatterplot and regression of relationship between swimming depth (in metres) at time of detection and current speed (m/s) for all tagged fish at the FORCE site. Shading on each side of the regression line represents standard error.

4.0 DISCUSSION

4.1 Size-related activity of striped bass

In this study, adult striped bass (fork lengths from 63 – 81 cm, mean age of 9.9 ±

0.97 years) were more active at and near the VEMCO receiver lines, and crossed the passage more than sub-adult bass (fork lengths of 38 – 61 cm, mean age of 5.5 ± 1.25 years). This pattern is consistent with the known life history patterns of Bay of Fundy striped bass. Prior studies have noted that striped bass mature at 3-5 years of age (fork lengths of 35-55 cm); prior to maturation they remain in brackish waters (Kimmerer et al., 2000; Richards and Rago, 1999). It is likely that most of the sub-adult striped bass

(tagged near Grand Pré) stayed within the Minas Basin during the study period, while post-spawning adults ventured further east to (and possibly beyond) the Minas Passage

(Bradford et al., 2012).

4.2 Effects of diurnal, tidal, and lunar cycles on movements

As was expected, striped bass movements tended to correspond with diurnal, and lunar cycles. The number of striped bass detections per hour was higher during hours of darkness, which may be due to increased foraging opportunity (Ng et al., 2007). Rulifson et al. (2008) noted that Bay of Fundy striped bass were captured in intertidal weirs (on tidal flats) more often at dusk and dawn than in full daylight or darkness. Similar diel

(day/night) patterns were seen in striped bass in a reservoir (Wilkerson and Fisher, 1997) and in a New Jersey estuary (Ng et al., 2007), though it is difficult to compare these patterns since the flow conditions of tidal flats, estuaries, and reservoirs differ greatly from those of the Minas Passage.

Previous studies have shown that VEMCO tag detection ranges in Minas Passage are reduced during high flow periods, especially during flood tides (Broome and Redden,

2012). Because of this effect, it is possible that many of the fish that were tagged were not always detected by receivers. Therefore, we assume that the detections observed are underestimates of the actual activity of tagged fishes at and near receiver stations in the

Minas Passage.

Detections of tagged striped bass were similar during ebbing tides than flooding tides, which was not expected, given that current speeds are lower on the ebb tide than flood tide in Minas Passage. Ebb tides have slower current speeds than flood tides because the tide takes longer to ebb than flood (Karsten, 2011). Future research on the

Bay of Fundy striped bass should attempt to clarify whether or not the differing flow conditions of ebb and flood tides have a meaningful impact on movements.

The lunar cycle and the moon’s effect on tides are known to influence the behaviour of many migratory fishes (Leggett, 1997; Binder et al., 2011). Previous studies of this phenomenon conducted in areas where tides are considerably smaller than those of the Bay of Fundy, show that lunar cycle relationships are mostly due to timing cues related to moonlight and diurnal tidal effects, as opposed to lunar effects on tidal ranges

(DeVries et al., 2004; Mohan et al., 2012). In the present study, it was found that striped bass made direct crossings, usually along the southern side of the passage, when tidal ranges were low (neap tides). Spring tides produce the greatest flows in the Minas

Passage, and while it appeared that striped bass avoided swimming through the passage during these periods, the lack of detections may be due to reduced detection range of receivers at high current speeds.

Striped bass movements could also be affected by prey behaviour. If smaller prey fish avoid the high flow periods, then striped bass may be following them and indirectly avoiding fast currents.

4.3 Seasonal timing of migrations

The results of this study showed that striped bass move in and around the Minas

Passage far more than expected. It has been assumed that post-spawners migrate from the

Shubenacadie River directly through the Minas Passage, into the Bay of Fundy and beyond; non-natal bass are believed to follow a similar migration route out of the passage

(Rulifson et al., 2008; COSEWIC, 2012a). However, the results of this study do not support a single, directed movement. Many Shubenacadie post-spawners appeared in the

Minas Passage in June and remained in the Minas Passage area for relatively long periods of time, moving back and forth within the passage multiple times. The benefits of such movements are unclear. It was predicted that the intense water flows would deter the fish from spending longer than necessary time in the tide race. The sub-adult bass, possibly non-natal, did not cross back and forth in the passage nearly as frequently as the post- spawners.

Peak detections in July and August support the timing of striped bass oceanic migrations, as observed in previous studies of the Bay of Fundy striped bass population

(COSEWIC, 2012a; Stokesbury et al., 2012), and of populations elsewhere (Robichaud-

LeBlanc et al., 1996; Wilkerson and Fisher, 1997; Douglas et al., 2009). Striped bass were detected within the passage late in the summer and during fall until mid-November.

The Bay of Fundy population is known to be unique, in that some individuals return from the Atlantic coast to overwinter in Grand Lake, NS (Bradford et al., 2012). This may

explain why some adult fish were detected multiple times in the passage during July and

August, and then again in October and November. Based on the movements described in

Figure 13, it appears that seven of the fifteen adults that were detected in the Minas

Passage travelled directly through the passage and returned in late fall. Six of the fifteen fish that crossed the Minas Passage (five adults and one sub-adult) were detected migrating out through the passage, and did not return, as was expected. Two adults spent much of the detection period moving back and forth within the passage, and may not have migrated to the outer bay and beyond. The ten remaining tagged fish (two adults and eight sub-adults) were detected by receivers in the passage, but their movements between receivers were too sporadic and time-separated to be analysed as direct crossings.

Fortunately, the project spans three years (2011-2013), with acoustic receivers currently deployed year-round (including winter of 2012/2013). Data collected by these moored receivers are likely to shed light on the winter movements of Bay of Fundy striped bass.

4.4 Swimming speeds

Swimming speeds of striped bass through the Minas Passage were calculated using the times and distances swum by directly crossing fish (<60 minutes from MPS line to AUL line). At first glance, swimming speeds up to 3.56 m/s (5.23 body lengths per second, or BL/s) seemed extreme, as some were higher than the critical swimming speed of striped bass, 4.9 BL/s (Hurst and Conover, 2001). However, the currents accounted for much of the swimming speed observed. Crossing fish always swam with the tide, which helps conserve much of their energy. However, it is questionable how well striped bass can control their location within the passage if they are travelling at maximum current

speeds (>5 m/s). This must be considered when determining the potential risks of fish- turbine interactions.

4.5 Swimming depth patterns

Based on this study; post-spawning striped bass tend to swim within a wider range of water column depth in the Minas Passage than the sub-adults, which were generally only detected in near surface waters (<25 m). These results were consistent with the depth distribution patterns shown for striped bass tagged in 2010 (Jeremy

Broome, unpublished data). It is likely that swimming depth is related to body size as large fish are stronger swimmers, and would therefore be more likely to pursue prey to any depth in the water column. Furthermore, striped bass are known to be opportunistic feeders, remaining inactive as much as possible to minimize energy costs (Tupper and

Able, 2000). It is possible that they swim deeper in the water column to avoid fast current speeds at the surface.

Interestingly, adult striped bass were detected only in near surface waters during the autumn months (October – November). While more data will be needed to determine whether this is a general pattern or not, it could be that the fish detected were foraging on a prey species that swims near the surface at that time of year.

4.6 Conclusions based on VEMCO acoustic telemetry

The use of VEMCO acoustic technology to track fish movements requires careful data analysis, including removal of duplicate detections, and minimization of conclusions based on multiple assumptions (e.g. receiver detection range, movement between receiver lines, and transmitter ping rates). By ensuring that the likelihood of false detections is low

(through uniquely coded transmitters), VEMCO has maximized the effectiveness of their technology. However, the movement patterns described herein are likely underestimates of fish activity near receivers. Factors contributing to loss of detections include:

1. Loss of receivers containing tag detections

2. Negative effects of high flows and associated ambient noise on range detection,

and

3. Incomplete transmissions.

Analysis of location and depth data showed that 12 of 15 detected adult striped bass swam through the FORCE tidal turbine test site in the Minas Passage and at depths that include turbine hub height. This indicates that the adult subset of the Bay of Fundy striped bass population may be at risk of direct and indirect fish-turbine interactions. If striped bass are unable to sense and avoid the turbines, they may be subjected to turbine strike, cavitation, and shearing, as was seen at the Annapolis Royal tidal power generating station. However, if fish are able to sense the presence of the turbines and move to avoid them, then an impact may be avoided. At this point, no studies have been performed on the ability of striped bass to respond to TISEC devices. One would assume, however, that any avoidance ability that striped bass might have would be reduced at very high current speeds. This study was unable to examine the movements of striped bass at high current speeds due to the effects of these speeds on detection performance of

VEMCO acoustic receivers. Other technologies will be required to examine the behaviour of fish in close proximity to in-stream tidal turbines. Currently, real risks to the striped bass population remain unknown.

4.7 Recommendations for further research

Due to the uncertainty surrounding the ability of striped bass to avoid the TISEC devices, it is recommended that research be conducted to test the abilities of striped bass to avoid large structures at high current speeds. To gather more detailed information on the activity and behaviour of striped bass in the FORCE test site, other types of sensors are required. The present study is unable to assess the localized movements of striped bass at the test site because VEMCO acoustic technology is limited to the detection of broader movements. Therefore, it is recommended that technologies, such as multibeam sonar and other imaging systems, be used to acquire more specific information on fish behaviour at the FORCE site. Placing an upward-facing sonar on the seafloor at the test site would enable fish movements to be tracked in an area designated for TISEC device installation.

There is also a need for measured environmental data (as opposed to modelled data) from the FORCE site. It is recommended that temperature, current speed, and depth sensors be moored on a platform at the site to improve the reliability of the data on which these types of studies are based.

The VEMCO receiver data collected during 2012 and 2013 will offer important insights. The overwintering behaviour of this striped bass population is currently unknown, and this unique winter dataset will provide valuable information in this regard.

With three years of data on striped bass movements, including winter movements, it may be possible to quantify the risk of turbine-fish interactions. This step is crucial to the progression of tidal energy development in the Minas Passage, given the endangered status of this population.

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54 Table A1. Detection data for each tagged fish in 2011. A. APPENDIX

Date Days Days % of # of of Station of before Date between days days Total # # of Tag Tagging FL Release first first first of last Station of first Days at with with of stations ID location (m) date detect detect detect detect last detect and last liberty detects detects detects visited 4987 Stew 0.68 05/24 06/26 MPS-04 33 07/31 AUL-13 35 68 16.2 11 234 19 4988 Stew 0.686 05/24 07/18 AUL-08 55 08/29 MPS-09 42 97 7.2 7 87 14 4989 Stew 0.726 05/24 NA NA NA NA NA NA NA NA 0 0 NA 4990 Stew 0.664 05/25 06/19 MPS-07 25 10/15 AUL-13 118 143 10.5 15 220 16 4991 Stew 0.641 05/25 NA NA NA NA NA NA NA NA 0 0 NA 4992 Stew 0.633 05/25 07/2 MPS-04 38 10/27 MPS-10 117 155 3.9 6 190 16 4993 Stew 0.639 05/25 NA NA NA NA NA NA NA NA 0 0 NA 4994 Stew 0.745 05/25 08/11 MPS-09 78 08/25 MPS-10 14 92 5.4 5 145 12 4995 Stew 0.81 05/25 06/23 AUL-09 29 10/29 MPS-04 128 157 1.9 3 46 11 4996 Stew 0.747 05/26 06/15 MPS-01 20 07/28 AUL-09 43 63 15.9 10 288 23 4997 Stew 0.699 05/26 07/26 MPS-09 61 08/03 AUL-02 8 69 2.9 2 34 5 4998 Stew 0.76 05/26 08/2 AUL-08 68 09/25 AUL-07 54 122 3.3 4 57 9 55 4999 Stew 0.689 05/26 07/6 MPS-01 41 07/06 AUL-07 0 41 2.4 1 43 6 5000 Stew 0.783 05/26 07/21 MPS-10 56 11/05 AUL-T3 107 163 5.5 9 129 19 5001 Stew 0.728 05/26 07/23 MPS-08 58 11/06 MPS-10 106 164 6.7 11 126 12 5002 Stew 0.679 05/26 06/23 MPS-04 28 06/23 MPS-10 0 28 3.6 1 28 5 5003 Stew 0.684 05/26 06/28 AUL-08 33 10/20 AUL-07 114 147 4.1 6 26 10 5004 Stew 0.644 05/26 NA NA NA NA NA NA NA NA 0 0 NA 5005 Stew 0.659 05/26 06/25 AUL-07 30 10/05 MPS-09 102 132 10.6 14 517 26 5006 Stew 0.703 05/26 NA NA NA NA NA NA NA NA 0 0 NA 5007 GP 0.427 06/25 08/30 MPS-12 66 09/02 AUL-02 3 69 4.3 3 32 4 5008 GP 0.486 06/25 NA NA NA NA NA NA NA NA 0 0 NA 5009 GP 0.538 06/25 10/30 AUL-07 127 10/30 AUL-05 0 127 0.8 1 2 2 5010 GP 0.43 06/25 10/30 MPS-09 127 10/30 MPS-09 0 127 0.8 1 1 1 5011 GP 0.526 06/25 08/11 AUL-08 47 11/13 MPS-09 94 141 2.1 3 22 10 5012 GP 0.403 06/25 NA NA NA NA NA NA NA NA 0 0 NA 5013 GP 0.607 06/25 07/8 MPS-05 13 08/31 AUL-02 54 67 9.0 6 79 14 5014 GP 0.496 06/25 NA NA NA NA NA NA NA NA 0 0 NA

5015 GP 0.524 06/25 NA NA NA NA NA NA NA NA 0 0 NA 5016 GP 0.55 06/25 09/3 AUL-05 70 09/03 AUL-05 0 70 1.4 1 37 3 5017 GP 0.392 06/25 NA NA NA NA NA NA NA NA 0 0 NA 5018 GP 0.388 06/26 NA NA NA NA NA NA NA NA 0 0 NA 5019 GP 0.544 06/26 10/21 AUL-09 117 10/21 AUL-09 0 117 0.9 1 2 1 5020 GP 0.494 06/26 08/20 MPS-12 55 10/22 MPS-12 63 118 3.4 4 13 6 5021 GP 0.421 06/26 NA NA NA NA NA NA NA NA 0 0 NA 5022 GP 0.42 06/26 NA NA NA NA NA NA NA NA 0 0 NA 5023 GP 0.382 06/26 10/29 MPS-09 125 10/31 AUL-11 2 127 1.6 2 2 2 5024 GP 0.46 06/26 NA NA NA NA NA NA NA NA 0 0 NA 5025 GP 0.47 06/26 10/28 MPS-08 124 10/29 MPS-08 1 125 1.6 2 6 1 5026 GP 0.53 06/26 NA NA NA NA NA NA NA NA 0 0 NA Notes: Column titles are explained as follows: “Tag ID” - the last 4 digits of the VEMCO transmitter ID code “Tagging location” - either Stewiacke (“Stew”) or Grand Pré (GP) “FL” – Fork length, measured in metres “Release date” - the date that the fish was tagged and released 56 “Date of first/last detect” - the date that the tagged fish was first/last detected by any deployed receiver

“Station of first/last detect” - the ID code of the receiver that first/last detected the fish “Days before first detect” - the number of days between the release of the tagged fish and its first detection “Days at liberty” - the number of days between the release of the tagged fish and the last detection of that fish “% of days with detects” – the percentage of days at liberty on which the fish was detected “# of days with detects” – the number of days at liberty on which the fish was detected “Total # of detects” – the total number of detections of that fish during the entire 2011 detection period “# of stations visited” – the total number of receiver stations where the fish was detected during the 2011 detection period

Table A2. Detection data for each receiver station in 2011. Total number of fish detected, number of detections, percentage of total detections, number of first detections and number of final detections are all listed as totals, and by tagging location (“Stew” = Stewiacke, “GP” = Grand Pré).

Station number # of fish detected # of detects % of all detects # of final detects # of first detects Stew GP Total Stew GP Total Stew GP Total Stew GP Total Stew GP Total AUL-01 1 1 2 20 3 23 0.845 0.127 0.972 0 0 0 0 0 0 AUL-02 5 2 7 20 15 35 0.845 0.634 1.479 1 2 3 0 0 0 AUL-03 9 3 12 106 35 141 4.480 1.479 5.959 0 1 1 0 0 0 AUL-04 7 1 8 9 13 22 0.380 0.549 0.930 0 0 0 0 0 0 AUL-05 5 2 7 24 4 28 1.014 0.169 1.183 0 1 1 0 1 1 AUL-06 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA AUL-07 10 3 13 92 3 95 3.888 0.127 4.015 3 0 3 1 1 2 AUL-08 9 2 11 76 6 82 3.212 0.254 3.466 0 0 0 3 1 4 AUL-09 6 3 9 40 10 50 1.691 0.423 2.113 1 1 2 1 1 2 AUL-10 9 2 11 155 5 160 6.551 0.211 6.762 0 0 0 0 0 0 AUL-11 5 3 8 18 3 21 0.761 0.127 0.888 0 1 1 0 0 0 57 AUL-12 6 0 6 140 0 140 5.917 0.000 5.917 0 0 0 0 0 0

AUL-13 8 0 8 53 0 53 2.240 0.000 2.240 2 0 2 0 0 0 AUL-14 4 1 5 52 25 77 2.198 1.057 3.254 0 0 0 0 0 0 AUL TOTAL NA NA NA 805 122 927 34.024 5.156 39.180 7 6 13 5 4 9 AUL-T1 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA AUL-T2 9 1 10 78 2 80 3.297 0.085 3.381 0 0 0 0 0 0 AUL-T3 9 0 9 73 0 73 3.085 0.000 3.085 1 0 1 0 0 0 AUL-T TOTAL NA NA NA 151 2 153 6.382 0.085 6.467 1 0 1 0 0 0 MPS-01 4 0 4 66 0 66 2.790 0.000 2.790 0 0 0 2 0 2 MPS-02 6 0 6 51 0 51 2.156 0.000 2.156 0 0 0 0 0 0 MPS-03 6 0 6 43 0 43 1.817 0.000 1.817 0 0 0 0 0 0 MPS-04 10 1 11 66 2 68 2.790 0.085 2.874 1 0 1 3 0 3 MPS-05 5 2 7 30 14 44 1.268 0.592 1.860 0 0 0 0 1 1 MPS-06 9 2 11 73 11 84 3.085 0.465 3.550 0 0 0 0 0 0 MPS-07 8 1 9 116 3 119 4.903 0.127 5.030 0 0 0 1 0 1

MPS-08 12 3 15 173 11 184 7.312 0.465 7.777 0 1 1 1 1 2 MPS-09 13 4 17 183 11 194 7.735 0.465 8.199 2 2 4 2 2 4 MPS-10 10 2 12 176 4 180 7.439 0.169 7.608 4 0 4 1 0 1 MPS-11 9 2 11 115 3 118 4.861 0.127 4.987 0 0 0 0 0 0 MPS-12 9 3 12 122 13 135 5.156 0.549 5.706 0 1 1 0 2 2 MPS TOTAL NA NA NA 1214 72 1286 51.310 3.043 54.353 7 4 11 10 6 16

Figure A1a. Detection locations of striped bass that were detected at !10 receiver stations during each month of the study period (beginning of June to end of November, 2011). Transmitter ID code is shown on the far left. Each row is a different individual, while each column is a different month.

Figure A1b. Detection locations of striped bass that were detected at !10 receiver stations during each month of the study period (beginning of June to end of November, 2011). Transmitter ID code is shown on the far left. Each row is a different individual, while each column is a different month.