PEI Oyster Monitoring Program Report. Technical Report # 251

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1 PEI Oyster Monitoring Program 2013 Report Technical Report # 251 PEI Department of Fisheries, Aquaculture and Rural Development Aquaculture Division P.O. Box Main Street Montague, PEI C0A 1R0

2 TABLE OF CONTENTS TABLE OF CONTENTS... i LIST OF FIGURES... ii LIST OF TABLES... iii INTRODUCTION... 1 METHODS... 2 Larvae (Spat-fall Prediction)... 3 Spat-fall... 5 Water Quality... 6 Tunicate Monitoring... 6 RESULTS... 7 Larvae (Spat-fall Prediction)... 7 Short-Term Collectors... 7 Water Temperature... 8 Tunicate Monitoring... 8 DISCUSSION Factors to Consider in Timing Collector Deployment Factors Affecting Oyster Set Limitations of the OMP APPENDIX I Maps Showing Oyster and Spat Monitoring Sites APPENDIX II Historical Spat Collection Data APPENDIX III Maps Displaying Current Known Range of Invasive Species in PEI i -

3 LIST OF FIGURES Figure 1. Bideford River seed collection area Figure 3. Sample collection sites for the 2013 Oyster Monitoring Program Figure 4. Oyster larvae, with foot extended, ready to set (365 µm) Figure 5. Short-term oyster spat collector (STC)... 5 Figure 6. Examining oyster collectors in Bideford River for tunicates Figure 7. Oyster Monitoring Sites in Bideford River: (1) Station site, (2) Paugh s Creek site, (3) Old Wharf site and (4) Green Park site Figure 8. Oyster Monitoring Sites in Foxley River: Site 5 - Lot 10, Site 6 - Gibb s Creek, and Site 7 - Lot Figure 9. Oyster Monitoring Site 8 - Percival River and Site 9 - Enmore River Figure 10. Oyster Monitoring Site 10 - Mill River and Site 11- Dock River Figure 11. Oyster Monitoring Site 12 - Bentick Cove Figure 12. Oyster Monitoring Site 13 - Dunk River and Site 14- Wilmot River Figure 13. Oyster Monitoring Site 15 - West River Figure 14. Oyster Monitoring Site 16- North River Figure 15. Oyster Monitoring in East River: Site 17- Cranberry Wharf and Site 18- MacWilliams Seafood Figure 16. Oyster Monitoring Site 19- Vernon River and Site 20- Orwell River Figure 17. Oyster Monitoring Site 21- Pownal Bay Figure 18. Current known range of the clubbed tunicate, Styela clava Figure 19. Current known range of the golden star tunicate, Botryllus schlosseri Figure 20. Current known range of the vase tunicate, Ciona intestinalis Figure 21. Current known range of the violet tunicate, Botrylloides violaceus Figure 22. Current known range of the green crab, Carcinus maenas Figure 23. Current known range of the oyster thief, Codium fragile Figure 24. Current known range of the oyster drill, Urosalpinx cinerea ii -

4 LIST OF TABLES Table Oyster Monitoring data from Site 1: Bideford River - Station Site... 9 Table Oyster Monitoring data from Site 2: Bideford River - Paugh s Creek Table Oyster Monitoring data from Site 3: Bideford River - Old Wharf Table Oyster Monitoring data from Site 4: Bideford River - Green Park Table Oyster Monitoring data from Site 5: Foxley River Lot Table Oyster Monitoring data from Site 6: Gibb s Creek and Site 7: Lot Table Oyster Monitoring data from Site 8: Percival River and Site 9: Enmore River Table Oyster Monitoring data from Site 10: Mill River and Site 11: Dock River Table Oyster Monitoring data from Site 12: Bentick Cove Table Oyster Monitoring data from Site 13: Dunk River and Site 14: Wilmot River Table Oyster Monitoring data from Site 15: West River and Site 16: North River Table Oyster Monitoring data from East River for Site 17: Cranberry Wharf and Site 18: MacWilliams Seafood Table Oyster Monitoring data from Site 19: Vernon River and Site 20: Orwell River. 19 Table 14. Oyster Monitoring data from Site 21: Pownal Bay Table 15. Summary of occurrence of oyster larvae > 250 μm at the sites in western PEI monitored in Table 16. Correlation of the presence of oyster larvae > 250 μm to oyster spat set on OMP collectors and grower collectors in the Bideford River in Table 17. PEI Shellfish Association collector deployment dates and spat set results from Table 18. Correlation of the combined OMP larvae (> 250 μm) and spat data with grower information from the Bideford River for iii -

INTRODUCTION The Prince Edward Island Oyster Monitoring Program (OMP) is a technical service provided to oyster growers by the Department of Fisheries, Aquaculture and Rural Development (DFARD).

5 INTRODUCTION The Prince Edward Island Oyster Monitoring Program (OMP) is a technical service provided to oyster growers by the Department of Fisheries, Aquaculture and Rural Development (DFARD). The OMP has operated annually since 2001, providing oyster growers with a variety of information to assist them in the collection of oyster spat and in the management of their oyster farming operations. The OMP serves primarily to provide information on spat-fall prediction to oyster farmers to assist them in determining when to deploy their spat collectors (Figure1). Information is collected on the number and size ranges of oyster larvae present in water samples collected from 21 sites throughout the province. In addition, oyster collectors are placed in the Bideford and Foxely River systems to monitor the timing and amount of oyster spat set. Water temperature data is collected for the majority of monitoring sites. The emphasis of the monitoring program is placed on the Bideford River, which is the primary oyster seed collection area on PEI. Comparison of the numbers and size ranges of oyster larvae with the amount of spat recruitment on OMP collectors and the water temperature data assists in predicting the timing and quantity of oyster spat settlement. This information is collected between June and late August every year and communicated to the growers as it is collected. Figure 1. Oyster growers deploying collectors in Bideford River

Monitoring for tunicates was added to the OMP in 2006 as a result of the clubbed tunicate, Styela clava, being identified in March Water and the potential for it to spread to the Bideford River.

6 Monitoring for tunicates was added to the OMP in 2006 as a result of the clubbed tunicate, Styela clava, being identified in March Water and the potential for it to spread to the Bideford River. The information collected from tunicate monitoring is provided to growers to make them aware of the infestation levels, primarily in the Bideford River. The oyster landings in PEI in 2012 were 6,143,281 lbs (aquaculture and wild fishery), with a landed value of $7,617,000. This was an increase of 229,971 lbs from landings in 2011 (see Figure 2). Landings have been relatively stable since Over the past several years, some bottom leases have been converted to off-bottom leases for suspended oyster culture and it is anticipated that cultured production may increase as a result. Figure 2. PEI oyster landings and values from 1980 to METHODS Data was collected from 21 sites for the OMP in 2013 (Figure 3). Two crews were utilized to collect the monitoring information with one crew responsible for eastern sites and the other crew responsible for western sites. Eastern sites included East River (Cranberry Wharf and MacWilliams Seafood), North River, West River, Pownal Bay, Orwell River and Vernon River

Western sites included four sites in Bideford River (Station, Paugh s Creek, Old Wharf and Green Park), three sites in Foxley River (Lot 10, Lot 6 and Gibbs Creek), Enmore River, Percival River, Mill

7 Western sites included four sites in Bideford River (Station, Paugh s Creek, Old Wharf and Green Park), three sites in Foxley River (Lot 10, Lot 6 and Gibbs Creek), Enmore River, Percival River, Mill River, Dock River, Bentick Cove, Dunk River and Wilmot River. Maps displaying the exact locations of the 21 sites are found in Appendix I. Figure 3. Sample collection sites for the 2013 Oyster Monitoring Program. Larvae (Spat-fall Prediction) Collection of water samples for larvae analysis occurred from late June until mid-august. Sampling frequency at these sites varied from 1-3 times per week with more frequent sampling occurring during the peak setting period. Water samples were obtained by towing a 2.5 meter (5 foot) long plankton net (30 cm diameter mouth, 63 µm mesh net and bucket), from surface to mid water column, at idle speed for approximately 5 minutes. The 63 µm net will retain all oyster larvae greater than 90 µm (4-6 day old larvae). Some smaller oyster larvae were also retained, as the net can become partially plugged during the tows. At the completion of the tow the bucket was removed from the net and the contents transferred to a 1L bottle. In the lab, the - 3 -

sample was screened to remove any larvae, algae or debris greater than the size range of oyster larvae, enabling oyster larvae to be observed more easily.

8 sample was screened to remove any larvae, algae or debris greater than the size range of oyster larvae, enabling oyster larvae to be observed more easily. The screened sample was transferred to a 1L beaker, where it was swirled to concentrate the larvae to the centre of the bottom of the beaker. A 1 ml subsample was collected from the concentrate with a pipette and placed on a slide for microscopic examination. Each larva in the subsample was measured and its size recorded (see Figure 4). If the sample had a very high number of larvae, a randomly chosen subsample was collected and all the larvae were counted in the subsample. The concentration of larvae present and their size range was made available to oyster growers via a voice mail system, which could be accessed by calling locally or toll free at In 2013 the monitoring results were also made available online at the following website ( The concentration of larvae was reported using the following scale: low (< 5), medium (6-20), high (> 20) and very high (> 100). Figure 4. Oyster larvae, with foot extended, ready to set (365 µm)

Spat-fall The amount of oyster recruitment was monitored at the Station site in the Bideford River and the Lot 10 site in Foxley River using oyster spat collectors.

9 Spat-fall The amount of oyster recruitment was monitored at the Station site in the Bideford River and the Lot 10 site in Foxley River using oyster spat collectors. The spat collectors consisted of a length of galvanized wire that contains three scallop shells (scallop shells are a very good substrate for the collection of oyster spat). The scallop shells were placed at three locations on the wire, one at30 cm (one foot), one at 60 cm (three feet), and one at 90 cm (five feet) (Figure 5). The scallop shells had a hole drilled in the center of the shell and were slid onto the length of wire, and supported at the correct location by a twist in the wire. Collectors were placed on a long line every two to three days (normally Monday, Wednesday and Friday) and recovered when the next collectors were deployed (short-term collector STC). The oyster spat on the top and bottom of each shell was counted using a dissecting microscope. Figure 5. Short-term oyster spat collector (STC) - 5 -

Water Quality Water temperature was measured at each site on the day of sampling. Salinity measurements were taken on a periodic basis and have not been included in this report.

10 Water Quality Water temperature was measured at each site on the day of sampling. Salinity measurements were taken on a periodic basis and have not been included in this report. Tunicate Monitoring Tunicate monitoring was initiated in 2006 in the Bideford River system because of the risk of the clubbed tunicate, S. clava, spreading into the system from the March Water area of Malpeque Bay. Since that time, the clubbed tunicate has been identified in the Bideford River (2007) and has become a significant fouling organism on crop and gear (especially on the submerged rack and bag systems). Since the majority of the oyster seed collected in the Bideford River system is transferred to leases in other areas or to public beds for enhancement purposes, there is a possibility that the tunicates could set on the oyster collectors and then be spread to other areas with the transfer of oyster spat from the collectors. As a result, it was decided in 2008 to make periodic observations of the oyster collector lines, oyster grow-out lines and mussel lines as a method to survey and provide information on tunicate densities. Figure 6. Examining oyster collectors in Bideford River for tunicates

11 RESULTS Larvae (Spat-fall Prediction) Tables 1 13 show the concentration, size ranges and total number (> 250 μm only) of larvae from water samples collected on sampling dates at each of the sites monitored. The first observation of oyster larvae was in late June. Larvae > 250 μm were first observed at the Bideford sites between y 8 th and 10 th and between y 8 th and 16 th at the other western sites (Table 15). The first high numbers of larvae > 250 μm were observed between y 8 th and 12 th at the Bideford sites and between y 8 th and 28 th at the other western sites (Table 15). Spat-fall Table 1 displays the spat set and short-term collector results from the Station site in the Bideford River. While the number of spat on each of the 3 shells from each collector was recorded, only the total number of spat per collector is included in these tables. As spat set can be quite variable within areas, and on different surfaces, it must be noted that the results on the department collectors may not be the same as those obtained on grower collectors from the same areas. Table 16 compares observations of larvae > 250 μm and spat set on STCs from the OMP and observations from grower collectors at the Station site. Short-Term Collectors The first observation of spat on STC at the Station site in the Bideford River was on y 12 th. The first appearance of high numbers of spat on STC was on y 15 th, four days after the first observation of larvae greater than 250 μm. The peak number of spat on STC was y 18 th, nine days following the initial observation of larvae greater than 250 μm

Water Temperature Temperature data that was collected at the monitoring sites is displayed in the Tables 1-13.

clava) continue to be observed on oyster grow-out lines and mussel lines located down river from the Shipyard Point in Bideford River.

As well the colonial tunicates continue to be observed in increasing abundance in Cascumpec Bay and in the Bideford River (Figure 7).

12 Water Temperature Temperature data that was collected at the monitoring sites is displayed in the Tables Water temperatures were within normal ranges and should have had no adverse effects on oyster larvae or spat. Tunicate Monitoring Increasing numbers of clubbed tunicates (S. clava) continue to be observed on oyster grow-out lines and mussel lines located down river from the Shipyard Point in Bideford River. The tunicate infestation in the Bideford River continues to increase with more clubbed tunicates being observed on gear and product in the area this year as compared with previous years (Figure 7). As well the colonial tunicates continue to be observed in increasing abundance in Cascumpec Bay and in the Bideford River (Figure 7). In 2013, the clubbed tunicate was identified for the first time in Egmont Bay. The tunicate was found on oyster gear in mid November. An Introduction and Transfer License, issued by DFO, is now required to move shellfish from these areas, to areas where those species of tunicates are not currently present. The current distribution (updated annually) of invasive tunicates (clubbed, vase, golden star and violet tunicate) on PEI can be found on the department s webpage at and in Appendix III of this report. The known ranges of the green crab, oyster thief and oyster drill are also included in Appendix III. Figure 7. Clubbed tunicate (Styela clava) on oyster spat collectors (left). Colonial tunicates on spat collectors (middle). Close-up image of clubbed tunicate (right)

13 Table Oyster Monitoring data from Site 1: Bideford River - Station Site Date Station Site Larvae Data # Spat on Collectors Water Temp. ** ( C) Total #* Size Range (μm) # > 250 μm STC June June 28 L y y 03 L y 04 M y 05 M y 08 V y 09 V y 10 H y 12 V y 15 V y 17 V y 19 V y 22 V y 24 H y 26 V y 29 H August 01 M August 05 L August 14 M August August micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high. ** Scallop shell collectors were deployed on the previous dates shown

14 Table Oyster Monitoring data from Site 2: Bideford River - Paugh s Creek Date Paugh s Creek Site Larvae Data Total #* Size Range (μm) # >250 μm Water Temp. ( C) June 27 L y y 05 H y 08 H y 10 V y 12 H y 15 V y 17 V y 22 V y 24 V y 26 V y 29 H August August micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm --- No information available * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

15 Table Oyster Monitoring data from Site 3: Bideford River - Old Wharf Date Old Wharf Site Larvae Data Total #* Size Range (μm) # >250 μm Water Temp. ( C) June June y 05 M y 08 H y 10 H y 12 V y 15 H y 19 V y 22 H y 29 M August 01 M August 05 L micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

16 Table Oyster Monitoring data from Site 4: Bideford River - Green Park Date Green Park Site Larvae Data Total #* Size Range (μm) # >250 μm Water Temp. ( C) June y 05 M y 08 H y 10 M y 12 H y 15 M y 22 V y 29 M August 01 H August 05 L micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

17 Table Oyster Monitoring data from Site 5: Foxley River Lot 10 Date Lot 10 Site Larvae Data # Spat on Collectors Water Temp. ** ( C) Total #* Size Range (μm) # > 250 μm STC June 26 L June y 02 H y 04 H y 08 V y 10 V y 12 V y 15 V y 17 V y 19 V y 22 V y 24 V y 26 H y 29 H August 01 V August 05 H micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high. ** Scallop shell collectors were deployed on the previous dates shown

18 Table Oyster Monitoring data from Site 6: Gibb s Creek and Site 7: Lot 6 Date Total #* Gibb s Creek Site Larvae Data Size Range (μm) # > 250 μm Water Temp. ( C) Date Total #* Lot 6 Site Larvae Data Size Range (μm) June 26 M y 02 M # > 250 μm Water Temp ( C) y 04 H y 04 H y 08 V y 08 V y 10 V y 10 V y 12 V y 12 V y 15 V y 15 V y 17 V y 17 V y 19 V y 19 V y 22 V y 22 V y 24 V y 24 V y 29 M y 29 V August 01 H August 01 V August 05 M August 05 M August 14 V August 22 M August 27 L micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm. --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

19 Table Oyster Monitoring data from Site 8: Percival River and Site 9: Enmore River Date Total #* Percival River Site Larvae Data Size Range (μm) # > 250 μm Water Temp. ( C) Date Enmore River Site Larvae Data Total #* Size Range (μm) June 27 L y 03 H y 03 M # > 250 μm Water Temp ( C) y 09 M y 09 V y 16 V y 16 V y 18 H y 18 V y 23 V y 23 V y 25 V y 25 H y 30 H y 30 L August 06 V August 06 V micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm. --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

20 Table Oyster Monitoring data from Site 10: Mill River and Site 11: Dock River Date Total #* Mill River Site Larvae Data Size Range (μm) # > 250 μm Water Temp. ( C) Date Total #* Dock River Site Larvae Data Size Range (μm) y 04 H # > 250 μm Water Temp ( C) y 16 V y 23 H y 30 L micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm. --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high. Table Oyster Monitoring data from Site 12: Bentick Cove Date Bentick Cove Site Larvae Data Total #* Size Range (μm) # >250 μm Water Temp. ( C) y 03 M y 09 V y 16 H y 18 V y 23 H y 30 H August 06 H y 03 M y 09 V micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

21 Table Oyster Monitoring data from Site 13: Dunk River and Site 14: Wilmot River Date Total #* Dunk River Site Larvae Data Size Range (μm) # > 250 μm Water Temp. ( C) Date Wilmot River Site Larvae Data Total #* Size Range (μm) # > 250 μm Water Temp ( C) y 03 H y 03 M y 09 V y 09 V y 16 H y 16 H y 23 H y 23 H y 30 M y 30 H August 06 H August 06 H micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high. Table Oyster Monitoring data from Site 15: West River and Site 16: North River Date Total #* West River Site Larvae Data Size Range (μm) # > 250 μm Water Temp. ( C) Date Total #* North River Site Larvae Data Size Range (μm) y 02 H # > 250 μm Water Temp ( C) y 12 M y 10 M y 24 V y 29 H August 06 M micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

22 Table Oyster Monitoring data from East River for Site 17: Cranberry Wharf and Site 18: MacWilliams Seafood Date Cranberry Wharf Site Larvae Data Total #* Size Range (μm) # > 250 μm Water Temp. ( C) Date MacWilliams Site Seafood Larvae Data Total #* Size Range (μm) # > 250 μm Water Temp ( C) June 25 M June 25 M June 28 M June 28 H y 02 M y 02 M y 05 H y 05 H y 08 H y 08 H y 10 H y 10 H y 12 H y 12 H y 15 H y 15 H y 17 H y 17 H y 19 H y 19 H y 22 H y 22 M y 24 M y 24 H y y 26 L y 29 M y 29 L y 31 L y 31 M August 05 M August 05 H August 07 L August 07 M August August 09 M August August micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm. --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

23 Table Oyster Monitoring data from Site 19: Vernon River and Site 20: Orwell River Date Total #* Vernon River Site Larvae Data Size Range (μm) # > 250 μm Water Temp. ( C) Date Total #* Orwell River Site Larvae Data Size Range (μm) # > 250 μm Water Temp ( C) June 25 L June 25 M June 28 L June 28 M y 02 L y 02 L y 05 H y 05 H y 08 V y 08 V y 10 V y 10 V y 12 H y 12 H y 15 H y 15 H y 17 H y 17 H y 19 H y 19 H y 22 H y 22 H y 24 H y 24 H y 26 M y 26 H y 29 M y 29 H y 31 H y 31 M August 05 H August 05 H August 07 H August 07 H August 09 L August 09 M August 14 L August 14 L August 20 L August micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm. --- No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

24 Table 14. Oyster Monitoring data from Site 21: Pownal Bay Date Pownal Bay Site Larvae Data Total #* Size Range (μm) # >250 μm Water Temp. ( C) y 08 V y 15 H y 19 H y 22 H y 26 M August 21 M micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm No information available. * Larvae numbers were reported as: 1-5 larvae as low, 6-19 as medium, as high and 100 as very high

25 Table 15. Summary of occurrence of oyster larvae > 250 μm at the sites in western PEI monitored in 2013 Site First Observation of Larvae > 250μm 1 st Observation 1 st Medium # 1 st High # Peak # s Station y 8 y 8 y 8 y 15 Paugh s Creek y 8 y 8 y 15 y 22 Old Wharf y 8 y 10 y 10 y 19 Green Park y 10 y 10 y 12 y 22 Mill River/Dock River y 16 y 16 y 16 y 16 Lot 10 Foxley River y 8 y 8 y 10 y 19 Lot 6 Foxley River y 8 y 8 y 8 y 19 Gibb s Creek y 8 y 8 y 8 y 12 Enmore River y 9 y 9 y 9 y 18 Percival River y 16 y 16 y 16 y 16 Bentick Cove y 16 y 18 y 18 y 23 Dunk River y 16 y 23 y 23 y 23 Wilmot River y 16 y 23 y 23 y 23 Table 16. Correlation of the presence of oyster larvae > 250 μm to oyster spat set on OMP collectors and grower collectors in the Bideford River in 2013 Site Larvae > 250μm OMP Short-term Collectors Grower Collectors * 1 st Observation 1 st High # s 1 st High # s Peak # s Deployed Spat Set Station y 8 y 8 y 15 y 17 y Moderate * PEI Shellfish Association and other grower information

26 DISCUSSION Factors to Consider in Timing Collector Deployment Oyster growers can utilize both historical and current information to assist them in determining when to deploy their oyster collectors. Historical information on collector deployment from previous years is available from various sources while current information on oyster larvae and spat set results are available through the Oyster Monitoring Program phone and website information systems. Some growers use historical information to determine when to deploy their collectors and typically put them out on dates that have given them success in previous years. A history of the timing of collector deployment and spat set results for the PEI Shellfish Association from is contained in Table 17 in Appendix III. During these years, the period from y 9th 15 th has been the most common period for collector deployment. However, there are years when deployment has been as early as y 4 th (2006) and as late as y 29 th (1992). The PEI Shellfish Association determines when to deploy their collectors based on the number and size of larvae observed in the larval tow samples. This variability of the timing of spawning and spat settlement from year to year suggests that the information available from the OMP will be of assistance to determine the best deployment dates. Growers can use the larvae size range and numbers, as reported on the OMP voice mail system and OMP website to estimate the length of time it will take for the larvae to start setting. While it is possible to use this method to estimate when to deploy collectors, variability in the weather and the number of larvae present in tows often make it advisable to wait until larvae are near set to make that determination. When larvae reach 250 μm they can set in 1 3 days, and it is recommended that collectors be in the water for a couple of days prior to this time to become conditioned to collect the optimum set. If the collector is left in the water too long the collectors may become unsuitably fouled for spat settlement. Thus, it would appear that if collectors are deployed when 250 μm larvae are initially seen they would be in the water in time to catch the first spat setting. The question remains as to whether collectors should be deployed this early, as larger numbers of setting-sized oyster larvae may appear some days after the initial appearance

27 Table 18 summarizes the spat set information for the Bideford River Station site from 2001 to 2013, in relation to the first appearance of 250 μm larvae and the 1 st high number of 250 μm larvae observed in the water samples collected for the OMP. The information presented in this table indicates that collectors deployed at the first appearance of 250 μm larvae have achieved a successful set. The timing of the peak set observed on short-term collectors and the set observed on the long-term collectors suggests collectors may have achieved a successful set if deployed when the first high numbers of larvae > 250 μm were reported. On average, grower collectors deployed 5 7 days after the first 250 μm larvae were observed were most effective in collecting spat. If aquaculturists deployed collectors when the first high numbers of larvae > 250 μm are reported they would often miss some of the first set, but be out in time to collect the high and peak numbers of oyster spat. The data also shows that peak oyster spat sets on the LTCs (collectors left out for time periods similar to grower collectors, but not treated with a lime immersion to remove fouling and predators) were observed on the collectors that were deployed on the same day as the first observation of oyster larvae greater than 250 μm. Factors Affecting Oyster Set There are many factors which may affect the final quantity of spat set on a collector, even if the collectors are set at the optimal time. Some of factors include: Low numbers of setting size larvae present. Low numbers of setting size larvae over an extended period of time and growers did not remove the fouling by immersing collectors in a lime solution to ensure the collectors would be free of fouling to allow for a collection of a later set. Two distinct sets and the collectors were not treated for fouling to collect the second set. No treatment of collectors resulting in predation and/or fouling. Anecdotal reports from oyster growers indicate that there was a moderate oyster set in There were no major problems caused by fouling organisms and predators in the Bideford River however shellfish association personnel were forced to carry out multiple anti-fouling treatments (lime dipping). The oyster set in East River and Vernon/Orwell Rivers was moderate as compared to previous years

28 Limitations of the OMP There are a number of factors that make sampling for oyster larvae a difficult process to standardize. Larvae sampling and spat collection are typically conducted in the mid to upper portions of the river systems. Larvae are thought to migrate up and down in the water column with respect to the tides and tows are conducted at specific times on specific days irrespective of tide and thus may be either rising or falling. As well, fresh water influence can cause the larvae to descend deeper in the water column, making them less available and more difficult to collect when sampling so heavy precipitation may impact quantities of larvae captured in tows. Current and boat speed when conducting tows will affect the amount of water that enters the net and potentially the numbers of larvae captured. These, and other factors, can cause variations in sampling results, making it difficult to compare larvae numbers between river systems or even from day to day within the same river system. Larvae sampling occurs every 2 days in some areas, but only twice a week in most areas. The time between sampling periods could mean that the 250 μm larvae may be present for up to four days before they are seen in the samples collected for the OMP. Determining the best time to deploy oyster collectors and how those collectors need to be treated is not an exact science, but it is hoped that the information contained in this report will assist growers in making this determination. The analysis of the success of spat collection over time described in this report is based solely on the larvae and collector data observed through the OMP and on grower results obtained through conversations with individual growers. If there are questions about the data contained in this report the reader may contact the Department at (902) , or by ing Jarrod Gunn McQuillan at jagunnmcquillan@gov.pe.ca

29 APPENDIX I Maps Showing Oyster and Spat Monitoring Sites

30 Figure 7. Oyster Monitoring Sites in Bideford River: (1) Station site, (2) Paugh s Creek site, (3) Old Wharf site and (4) Green Park site. Figure 8. Oyster Monitoring Sites in Foxley River: Site 5 - Lot 10, Site 6 - Gibb s Creek, and Site 7 - Lot

31 Figure 9. Oyster Monitoring Site 8 - Percival River and Site 9 - Enmore River. Figure 10. Oyster Monitoring Site 10 - Mill River and Site 11- Dock River

32 Figure 11. Oyster Monitoring Site 12 - Bentick Cove. Figure 12. Oyster Monitoring Site 13 - Dunk River and Site 14- Wilmot River

33 Figure 13. Oyster Monitoring Site 15 - West River. Figure 14. Oyster Monitoring Site 16- North River

34 Figure 15. Oyster Monitoring in East River: Site 17- Cranberry Wharf and Site 18- MacWilliams Seafood. Figure 16. Oyster Monitoring Site 19- Vernon River and Site 20- Orwell River

35 Figure 17. Oyster Monitoring Site 21- Pownal Bay

36 APPENDIX II Historical Spat Collection Data

37 Table 17. PEI Shellfish Association collector deployment dates and spat set results from Year Collector Deployment Date Set Results 1990 y 20 Good 1991 y 15 Good 1992 y 29 Fair 1993 y 15 Fair 1994 y 11 Good 1995 y 10 Good 1996 y 15 Good 1997 y 11 Fair 1998 y 9 Good 1999 y 5 Good 2000 y 10 Poor 2001 y 9 Poor 2002 y 15 Good 2003 y 14 Good 2004 y 21 Good 2005 y 18 Good 2006 y 4 Good 2007 y 16 Good 2008 y 10 Good 2009 y 13 Poor - Good 2010 y 12 Good 2011 y 18 Poor-Good 2012 y 11 Good 2013 y Moderate

38 Table 18. Correlation of the combined OMP larvae (> 250 μm) and spat data with grower information from the Bideford River for Year Larvae > 250 μm Spat Set (STC) Spat Set (LTC) Grower Collectors * 1 st 1st High # Peak 1 st 1st High # Peak Set Period Peak Deployed Spat Set Aug Aug Aug 9 6 Aug Nil (most) Aug Aug Heavy Nil-heavy Aug Aug Aug Moderate & 21 Jun Light- Heavy Aug Aug Aug Heavy Aug Heavy Aug Aug ? Nil-heavy Aug ? Heavy Aug Nil-heavy Aug Heavy Moderate * PEI Shellfish Association and other grower information. --- No information available

39 APPENDIX III Maps Displaying Current Known Range of Invasive Species in PEI

40 Figure 18. Current known range of the clubbed tunicate, Styela clava

41 Figure 19. Current known range of the golden star tunicate, Botryllus schlosseri

42 Figure 20. Current known range of the vase tunicate, Ciona intestinalis

43 Figure 21. Current known range of the violet tunicate, Botrylloides violaceus

44 Figure 22. Current known range of the green crab, Carcinus maenas

45 Figure 23. Current known range of the oyster thief, Codium fragile

46 Figure 24. Current known range of the oyster drill, Urosalpinx cinerea

PEI Oyster Monitoring Program Report. Technical Report # 249

PEI Oyster Monitoring Program 2012 Report Technical Report # 249 By Paul Burleigh, Mark MacLeod, Chelsey Ellis & Jarrod Gunn McQuillan PEI Department of Fisheries, Aquaculture and Rural Development Aquaculture