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Transcript of PEI Oyster Monitoring Program 2013 Report · Oyster growers deploying collectors in Bideford River....
PEI Oyster Monitoring Program
2013 Report
Technical Report # 251
PEI Department of Fisheries, Aquaculture and Rural Development
Aquaculture Division
P.O. Box 1180
548 Main Street
Montague, PEI
C0A 1R0
- i -
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 .............................................................................................................................. 22
Factors to Consider in Timing Collector Deployment ............................................................. 22 Factors Affecting Oyster Set ..................................................................................................... 23
Limitations of the OMP ............................................................................................................. 24
APPENDIX I Maps Showing Oyster and Spat Monitoring Sites ................................................ 25
APPENDIX II Historical Spat Collection Data ........................................................................... 32
APPENDIX III Maps Displaying Current Known Range of Invasive Species in PEI ............... 35
- ii -
LIST OF FIGURES
Figure 1. Bideford River seed collection area. ............................................................................... 1
Figure 3. Sample collection sites for the 2013 Oyster Monitoring Program. ................................. 3
Figure 4. Oyster larvae, with foot extended, ready to set (365 µm). .............................................. 4
Figure 5. Short-term oyster spat collector (STC)............................................................................ 5
Figure 6. Examining oyster collectors in Bideford River for tunicates. ......................................... 6
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. ........................................................................................ 26
Figure 8. Oyster Monitoring Sites in Foxley River: Site 5 - Lot 10, Site 6 - Gibb’s Creek, and
Site 7 - Lot 6. ................................................................................................................................ 26
Figure 9. Oyster Monitoring Site 8 - Percival River and Site 9 - Enmore River. ......................... 27
Figure 10. Oyster Monitoring Site 10 - Mill River and Site 11- Dock River ............................... 27
Figure 11. Oyster Monitoring Site 12 - Bentick Cove. ................................................................. 28
Figure 12. Oyster Monitoring Site 13 - Dunk River and Site 14- Wilmot River. ........................ 28
Figure 13. Oyster Monitoring Site 15 - West River...................................................................... 29
Figure 14. Oyster Monitoring Site 16- North River. .................................................................... 29
Figure 15. Oyster Monitoring in East River: Site 17- Cranberry Wharf and Site 18- MacWilliams
Seafood. ........................................................................................................................................ 30
Figure 16. Oyster Monitoring Site 19- Vernon River and Site 20- Orwell River. ....................... 30
Figure 17. Oyster Monitoring Site 21- Pownal Bay. .................................................................... 31
Figure 18. Current known range of the clubbed tunicate, Styela clava. ....................................... 36
Figure 19. Current known range of the golden star tunicate, Botryllus schlosseri. ...................... 37
Figure 20. Current known range of the vase tunicate, Ciona intestinalis. .................................... 38
Figure 21. Current known range of the violet tunicate, Botrylloides violaceus. .......................... 39
Figure 22. Current known range of the green crab, Carcinus maenas. ........................................ 40
Figure 23. Current known range of the oyster thief, Codium fragile. .......................................... 41
Figure 24. Current known range of the oyster drill, Urosalpinx cinerea. .................................... 42
- iii -
LIST OF TABLES
Table 1. 2013 Oyster Monitoring data from Site 1: Bideford River - Station Site ......................... 9
Table 2. 2013 Oyster Monitoring data from Site 2: Bideford River - Paugh’s Creek .................. 10
Table 3. 2013 Oyster Monitoring data from Site 3: Bideford River - Old Wharf ........................ 11
Table 4. 2013 Oyster Monitoring data from Site 4: Bideford River - Green Park ....................... 12
Table 5. 2013 Oyster Monitoring data from Site 5: Foxley River – Lot 10 ................................. 13
Table 6. 2013 Oyster Monitoring data from Site 6: Gibb’s Creek and Site 7: Lot 6 .................... 14
Table 7. 2013 Oyster Monitoring data from Site 8: Percival River and Site 9: Enmore River .... 15
Table 8. 2013 Oyster Monitoring data from Site 10: Mill River and Site 11: Dock River .......... 16
Table 9. 2013 Oyster Monitoring data from Site 12: Bentick Cove ............................................. 16
Table 10. 2013 Oyster Monitoring data from Site 13: Dunk River and Site 14: Wilmot River ... 17
Table 11. 2013 Oyster Monitoring data from Site 15: West River and Site 16: North River ...... 17
Table 12. 2013 Oyster Monitoring data from East River for Site 17: Cranberry Wharf and Site
18: MacWilliams Seafood............................................................................................................. 18
Table 13. 2013 Oyster Monitoring data from Site 19: Vernon River and Site 20: Orwell River . 19
Table 14. Oyster Monitoring data from Site 21: Pownal Bay ...................................................... 20
Table 15. Summary of occurrence of oyster larvae > 250 μm at the sites in western PEI
monitored in 2013 ......................................................................................................................... 21
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 ................................................... 21
Table 17. PEI Shellfish Association collector deployment dates and spat set results from 1990 –
2013............................................................................................................................................... 33
Table 18. Correlation of the combined OMP larvae (> 250 μm) and spat data with grower
information from the Bideford River for 2001-2013. ................................................................... 34
- 1 -
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.
- 2 -
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 2000. 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 2012.
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.
- 3 -
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
- 4 -
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 831-5801 locally or toll free at 1-888-831-5801. In 2013 the
monitoring results were also made available online at the following website
(http://www.gov.pe.ca/fard/oystermonitoring/). 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).
- 5 -
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)
- 6 -
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.
- 7 -
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 July 8th
and 10th
and between July 8th
and 16th
at the other western sites
(Table 15). The first high numbers of larvae > 250 μm were observed between July 8th
and 12th
at
the Bideford sites and between July 8th
and 28th
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 July 12th
.
The first appearance of high numbers of spat on STC was on July 15th
, four days after the first
observation of larvae greater than 250 μm. The peak number of spat on STC was July 18th
, nine
days following the initial observation of larvae greater than 250 μm.
- 8 -
Water Temperature
Temperature data that was collected at the monitoring sites is displayed in the Tables 1-13.
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 www.gov.pe.ca/fard 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).
- 9 -
Table 1. 2013 Oyster Monitoring data from Site 1: Bideford River - Station Site
Date Station Site Larvae Data Water Temp.
(°C)
# Spat on Collectors
**
Total #* Size Range (μm) # > 250 μm STC
June 24 0 --- 0 21.0 ---
June 28 L-1 100 0 17.8 ---
July 02 0 --- 0 20.5 ---
July 03 L-3 90-150 0 21.1 ---
July 04 M-9 100-120 0 20.5 ---
July 05 M-6 120-140 0 20.9 ---
July 08 V-135 90-290 27 --- ---
July 09 V-112 90-340 30 --- ---
July 10 H-52 90-350 20 23.5 ---
July 12 V-226 120-360 139 --- 8
July 15 V-1050 120-370 913 25.3 110
July 17 V-528 100-360 481 25.2 1247
July 19 V-194 160-350 155 23.1 537
July 22 V-734 120-360 561 23.9 419
July 24 H-42 200-330 38 22.7 ---
July 26 V-296 150-340 232 22.3 ---
July 29 H-74 80-330 62 20.9 ---
August 01 M-11 90-320 5 24.5 ---
August 05 L-1 140 0 23.9 ---
August 14 M-6 120-270 1 22.9 ---
August 22 0 --- 0 23.5 ---
August 27 0 --- 0 21.7 ---
250 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, 20 - 99 as high and ≥ 100 as very high.
** Scallop shell collectors were deployed on the previous dates shown.
- 10 -
Table 2. 2013 Oyster Monitoring data from Site 2: Bideford River - Paugh’s Creek
Date Paugh’s Creek Site Larvae Data Water Temp.
(°C) Total #* Size Range (μm) # >250 μm
June 27 L-1 75 0 18.4
July 02 0 --- 0 20.4
July 05 H-90 --- --- 21.2
July 08 H-66 120-290 11 22.7
July 10 V-111 110-350 46 23.6
July 12 H-77 130-360 58 22.8
July 15 V-314 120-350 209 26.4
July 17 V-522 160-360 477 26.1
July 22 V-2435 110-360 2005 24.0
July 24 V-128 130-360 101 23.0
July 26 V-160 100-330 87 22.7
July 29 H-21 160-330 14 21.4
August 01 0 0 0 25.5
August 05 0 0 0 25.6
250 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, 20 - 99 as high and ≥ 100 as very high.
- 11 -
Table 3. 2013 Oyster Monitoring data from Site 3: Bideford River - Old Wharf
Date Old Wharf Site Larvae Data Water Temp.
(°C) Total #* Size Range (μm) # >250 μm
June 27 0 --- 0 19.0
June 28 0 --- 0 17.9
July 05 M-13 80-200 0 21.8
July 08 H-41 90-310 2 22.3
July 10 H-54 100-350 29 23.0
July 12 V-145 120-370 84 22.6
July 15 H-58 170-360 47 25.2
July 19 V-555 110-360 451 22.9
July 22 H-52 110-350 35 24.0
July 29 M-19 100-320 12 20.7
August 01 M-16 110-310 4 23.1
August 05 L-2 300-340 2 23.3
250 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, 20 - 99 as high and ≥ 100 as very high.
- 12 -
Table 4. 2013 Oyster Monitoring data from Site 4: Bideford River - Green Park
Date Green Park Site Larvae Data Water Temp.
(°C) Total #* Size Range (μm) # >250 μm
June 24 0 --- 0 20.5
July 05 M-6 130-160 0 22.1
July 08 H-34 100-240 0 22.3
July 10 M-11 190-330 8 22.8
July 12 H-45 90-350 24 22.5
July 15 M-10 110-330 2 24.6
July 22 V-136 120-350 94 23.9
July 29 M-18 150-340 16 20.7
August 01 H-34 150-350 26 22.2
August 05 L-3 110-130 0 22.5
250 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, 20 - 99 as high and ≥ 100 as very high.
- 13 -
Table 5. 2013 Oyster Monitoring data from Site 5: Foxley River – Lot 10
Date Lot 10 Site Larvae Data Water Temp.
(°C)
# Spat on Collectors
**
Total #* Size Range (μm) # > 250 μm STC
June 26 L-4 70-80 0 20.6 ---
June 28 0 --- 0 16.2 ---
July 02 H-31 80-130 0 21.6 ---
July 04 H-68 70-170 0 22.8 ---
July 08 V-356 90-280 14 24.2 ---
July 10 V-115 90-320 24 23.2 ---
July 12 V-190 90-350 68 22.9 28
July 15 V-240 100-350 230 24.9 451
July 17 V-130 160-350 118 24.5 674
July 19 V-458 100-350 421 22.9 395
July 22 V-273 100-370 233 22.3 689
July 24 V-174 110-370 130 21.5 132
July 26 H-90 80-350 58 21.5 39
July 29 H-20 110-320 14 20.7 ---
August 01 V-236 90-340 180 22.3 ---
August 05 H-62 120-320 38 22.3 ---
250 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, 20 - 99 as high and ≥ 100 as very high.
** Scallop shell collectors were deployed on the previous dates shown.
- 14 -
Table 6. 2013 Oyster Monitoring data from Site 6: Gibb’s Creek and Site 7: Lot 6
Date
Gibb’s Creek Site Larvae Data
Date
Lot 6 Site Larvae Data
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp.
(°C)
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp
(°C)
June 26 M-9 70-95 0 19.4 --- --- --- --- ---
July 02 M-7 80-100 0 21.2 --- --- --- --- ---
July 04 H-80 --- 0 22.8 July 04 H-93 70-190 0 21.7
July 08 V-849 100-260 36 24.4 July 08 V-776 90-260 63 23.5
July 10 V-579 110-330 108 25.2 July 10 V-482 100-340 79 23.1
July 12 V-542 110-320 377 22.9 July 12 V-456 110-350 254 22.6
July 15 V-164 140-370 152 27 July 15 V-896 170-360 859 24.8
July 17 V-227 190-350 204 25 July 17 V-960 220-360 908 23.9
July 19 V-131 110-350 96 22.5 July 19 V-1312 100-360 1137 22.7
July 22 V-136 120-350 94 23.9 July 22 V-372 90-360 307 21.8
July 24 V-182 110-350 156 21.9 July 24 V-328 120-360 296 21.2
July 29 M-8 80-90 0 21.2 July 29 V-274 110-350 234 20.2
August 01 H-69 90-330 17 22.8 August 01 V-148 90-330 50 22.1
August 05 M-18 90-280 1 24.6 August 05 M-18 90-330 2 22.1
--- --- --- --- --- August 14 V-160 90-330 10 21.8
--- --- --- --- --- August 22 M-7 150-300 2 22.4
--- --- --- --- --- August 27 L-0 0 0 20.9
250 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, 20 - 99 as high and ≥ 100 as very high.
- 15 -
Table 7. 2013 Oyster Monitoring data from Site 8: Percival River and Site 9: Enmore River
Date
Percival River Site Larvae Data
Date
Enmore River Site Larvae Data
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp.
(°C)
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp
(°C)
--- --- --- --- --- June 27 L-2 70-80 0 18
July 03 H-21 80-130 0 20.6 July 03 M-14 80-150 0 21
July 09 M-16 80-150 0 23.0 July 09 V-1520 80-300 62 23.1
July 16 V-754 80-340 612 25.9 July 16 V-362 80-340 225 26.3
July 18 H-77 80-340 18 23.1 July 18 V-427 90-330 390 23.2
July 23 V-208 80-320 24 22.8 July 23 V-192 70-320 46 23.3
July 25 V-122 70-320 51 22.6 July 25 H-58 80-310 2 23.5
July 30 H-74 90-330 48 21.0 July 30 L-3 80-270 1 21.3
August 06 V-186 90-270 8 22.3 August 06 V-572 80-130 0 22.3
250 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, 20 - 99 as high and ≥ 100 as very high.
- 16 -
Table 8. 2013 Oyster Monitoring data from Site 10: Mill River and Site 11: Dock River
Date
Mill River Site Larvae Data
Date
Dock River Site Larvae Data
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp.
(°C)
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp
(°C)
July 04 H-25 70-130 0 20.8 --- --- --- --- ---
--- --- --- --- --- July 16 V-1576 150-350 1321 23.3
July 23 H-72 80-340 10 21.3 --- --- --- --- ---
--- --- --- --- --- July 30 L-4 200-290 1 20.9
250 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, 20 - 99 as high and ≥ 100 as very high.
Table 9. 2013 Oyster Monitoring data from Site 12: Bentick Cove
Date Bentick Cove Site Larvae Data Water Temp.
(°C) Total #* Size Range (μm) # >250 μm
July 03 M-14 85-110 0 20.5
July 09 V-100 85-180 0 23.4
July 16 H-24 130-350 2 24.5
July 18 V-116 80-340 62 25.6
July 23 H-80 110-350 64 22.7
July 30 H-22 140-340 12 21.9
August 06 H-24 100-350 4 22.2
July 03 M-14 85-110 0 20.5
July 09 V-100 85-180 0 23.4
250 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, 20 - 99 as high and ≥ 100 as very high.
- 17 -
Table 10. 2013 Oyster Monitoring data from Site 13: Dunk River and Site 14: Wilmot River
Date
Dunk River Site Larvae Data
Date
Wilmot River Site Larvae Data
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp.
(°C)
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp
(°C)
July 03 H-24 75-90 0 20.5 July 03 M-19 78-95 0 20.4
July 09 V-100 70-160 0 22.7 July 09 V-100 70-140 0 22.2
July 16 H-35 80-320 1 24.6 July 16 H-73 70-240 0 25.2
July 23 H-98 90-350 58 22.0 July 23 H-80 100-340 48 ---
July 30 M-17 80-360 8 21.6 July 30 H-35 70-350 15 21.5
August 06 H-21 80-360 1 21.5 August 06 H-21 110-340 1 21.5
250 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, 20 - 99 as high and ≥ 100 as very high.
Table 11. 2013 Oyster Monitoring data from Site 15: West River and Site 16: North River
Date
West River Site Larvae Data
Date
North River Site Larvae Data
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp.
(°C)
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp
(°C)
--- --- --- --- --- July 02 H-48 75-150 0 21
July 12 M-13 70-85 0 19 July 10 M-7 90-320 3 21.3
July 24 V-100 80-125 0 21.3 July 29 H-48 110-330 3 22.5
August 06 M-16 115-340 14 21.4 --- --- --- --- ---
250 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, 20 - 99 as high and ≥ 100 as very high.
- 18 -
Table 12. 2013 Oyster Monitoring data from East River for Site 17: Cranberry Wharf and
Site 18: MacWilliams Seafood
Date
Cranberry Wharf Site Larvae Data
Date
MacWilliams Site Seafood Larvae
Data
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp.
(°C)
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp
(°C)
June 25 M-11 68-74 0 23.0 June 25 M-6 62 - 75 0 22.4
June 28 M-6 70-100 0 18.8 June 28 H-21 70-80 0 18.4
July 02 M-7 75-100 0 20.8 July 02 M-17 80-90 0 20.4
July 05 H-20 70-140 0 22.9 July 05 H-25 75-120 0 21.7
July 08 H-34 75-135 0 24.2 July 08 H-51 75-120 0 23.8
July 10 H-23 85-135 0 21.3 July 10 H-39 80-130 0 22.5
July 12 H-30 85-170 0 23.2 July 12 H-29 75-170 0 23.2
July 15 H-27 130-220 0 25.1 July 15 H-33 140-250 1 24.9
July 17 H-25 150-330 3 24.1 July 17 H-27 90-320 5 23.8
July 19 H-84 140-350 60 22.8 July 19 H-68 90-330 27 23.0
July 22 H-27 120-340 11 23.7 July 22 M-18 100-320 9 23.0
July 24 M-15 90-320 11 22.5 July 24 H-30 80-330 15 ---
July 26 0 --- 0 22.2 July 26 L-1 320 1 21.9
July 29 M-6 200-330 5 21.7 July 29 L-2 200-350 0 21.9
July 31 L-3 120-330 2 22.6 July 31 M-13 160-330 10 22.2
August 05 M-8 80-320 1 24.0 August 05 H-20 120-350 4 23.5
August 07 L-2 120-140 0 23.1 August 07 M-12 120-350 1 23.0
August 09 0 --- 0 23.5 August 09 M-11 180-330 4 23.1
August 20 0 --- 0 22.5 --- --- --- --- ---
August 28 0 --- 0 20.8 --- --- --- --- ---
250 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, 20 - 99 as high and ≥ 100 as very high.
- 19 -
Table 13. 2013 Oyster Monitoring data from Site 19: Vernon River and Site 20: Orwell River
Date
Vernon River Site Larvae Data
Date
Orwell River Site Larvae Data
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp.
(°C)
Total
#*
Size
Range
(μm)
# >
250
μm
Water
Temp
(°C)
June 25 L-3 73-80 0 21.7 June 25 M-13 65-80 0 20.9
June 28 L-4 80-90 0 17.0 June 28 M-12 75-90 0 17.2
July 02 L-4 75-90 0 20.6 July 02 L-4 80-100 0 20.2
July 05 H-27 75-115 0 21.3 July 05 H-30 70-90 0 20.6
July 08 V-100 80-110 0 24.9 July 08 V-100 75-115 0 23.7
July 10 V-100 80-140 0 22.6 July 10 V-100 80-130 0 22.0
July 12 H-52 90-190 0 22.8 July 12 H-64 80-175 0 21.6
July 15 H-39 130-215 0 23.2 July 15 H-29 110-220 0 24.0
July 17 H-59 110-320 7 23.1 July 17 H-43 130-330 4 22.9
July 19 H-62 110-330 8 22.4 July 19 H-70 130-340 12 21.9
July 22 H-82 90-350 40 22.8 July 22 H-44 180-340 24 22.5
July 24 H-23 130-340 15 22.3 July 24 H-30 90-330 15 22.1
July 26 M-17 210-330 12 21.4 July 26 H-21 130-330 11 21.8
July 29 M-9 300-340 9 21.2 July 29 H-24 200-350 20 21.3
July 31 H-28 120-340 15 23.2 July 31 M-7 130-310 1 22.7
August 05 H-47 70-320 2 24.1 August 05 H-84 80-340 4 23.7
August 07 H-42 100-240 1 23.3 August 07 H-30 120-350 2 22.6
August 09 L-4 180-280 1 22.3 August 09 M-13 150-270 1 23.3
August 14 L-1 210 0 22.5 August 14 L-3 110-320 1 22.5
August 20 L-4 310-335 4 22.2 --- --- --- --- ---
August 28 0 --- 0 21.1 --- --- --- --- ---
250 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, 20 - 99 as high and ≥ 100 as very high.
- 20 -
Table 14. Oyster Monitoring data from Site 21: Pownal Bay
Date Pownal Bay Site Larvae Data Water Temp.
(°C) Total #* Size Range (μm) # >250 μm
July 08 V-100 85-140 0 24.0
July 15 H-34 130-250 1 24.9
July 19 H-58 80-250 0 22.2
July 22 H-32 130-320 5 22.5
July 26 M-15 310-340 15 ---
August 21 M-12 280-340 12 22.1
250 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, 20 - 99 as high and ≥ 100 as very high.
- 21 -
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
1st Observation 1
st Medium # 1
st High # Peak #’s
Station July 8 July 8 July 8 July 15
Paugh’s Creek July 8 July 8 July 15 July 22
Old Wharf July 8 July 10 July 10 July 19
Green Park July 10 July 10 July 12 July 22
Mill River/Dock River July 16 July 16 July 16 July 16
Lot 10 Foxley River July 8 July 8 July 10 July 19
Lot 6 Foxley River July 8 July 8 July 8 July 19
Gibb’s Creek July 8 July 8 July 8 July 12
Enmore River July 9 July 9 July 9 July 18
Percival River July 16 July 16 July 16 July 16
Bentick Cove July 16 July 18 July 18 July 23
Dunk River July 16 July 23 July 23 July 23
Wilmot River July 16 July 23 July 23 July 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 *
1st Observation 1
st High #’s 1
st High #’s Peak #’s Deployed Spat Set
Station July 8 July 8 July 15 July 17 July 11-12 Moderate
* PEI Shellfish Association and other grower information.
- 22 -
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 1990-
2013 is contained in Table 17 in Appendix III. During these years, the period from July 9th –
15th
has been the most common period for collector deployment. However, there are years when
deployment has been as early as July 4th
(2006) and as late as July 29th
(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.
- 23 -
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 1st 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 2013.
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.
- 24 -
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)
838-0910, or by e-mailing Jarrod Gunn McQuillan at [email protected].
- 25 -
APPENDIX I
Maps Showing Oyster and Spat Monitoring Sites
- 26 -
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 6.
- 27 -
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
- 28 -
Figure 11. Oyster Monitoring Site 12 - Bentick Cove.
Figure 12. Oyster Monitoring Site 13 - Dunk River and Site 14- Wilmot River.
- 29 -
Figure 13. Oyster Monitoring Site 15 - West River.
Figure 14. Oyster Monitoring Site 16- North River.
- 30 -
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.
- 31 -
Figure 17. Oyster Monitoring Site 21- Pownal Bay.
- 32 -
APPENDIX II
Historical Spat Collection Data
- 33 -
Table 17. PEI Shellfish Association collector deployment dates and spat set results from
1990 – 2013.
Year Collector Deployment Date Set Results
1990 July 20 Good
1991 July 15 Good
1992 July 29 Fair
1993 July 15 Fair
1994 July 11 Good
1995 July 10 Good
1996 July 15 Good
1997 July 11 Fair
1998 July 9 Good
1999 July 5 Good
2000 July 10 Poor
2001 July 9 Poor
2002 July 15 Good
2003 July 14 Good
2004 July 21 Good
2005 July 18 Good
2006 July 4 Good
2007 July 16 Good
2008 July 10 Good
2009 July 13 Poor - Good
2010 July 12 Good
2011 July 18 Poor-Good
2012 July 11 Good
2013 July 11-12 Moderate
- 34 -
Table 18. Correlation of the combined OMP larvae (> 250 μm) and spat data with grower
information from the Bideford River for 2001-2013.
Year
Larvae > 250 μm Spat Set (STC) Spat Set (LTC) Grower Collectors *
1st 1st High
# Peak 1st
1st High # Peak Set
Period
Peak Deployed Spat Set
2001 Jul
6-18
Jul 9-
Aug 3
Jul 17-
Aug 3
Jul
11
Jul
13-17
Jul 13-
Aug 9
Jul 6 –
Aug 6
Jul
11-30
Jul
9-11
Nil
(most)
2002 Jul
11-17
Jul
17-22
Jul 19-
Aug 23
Jul
17-19
Jul
19
Jul
26
Jul 12-
Aug 5
Jul
12-22
Jul
15-18
Heavy
2003 Jul
8-11
Jul
9-11
Jul
14-25
Jul
11-14
Jul
11-18
Jul
14-21
Jul
11-21
Jul
11-18
Jul
15-18
Nil-heavy
2004 Jul
14-22
Jul
22
Jul 22-
Aug 9
Jul
20-22
Jul
22-28
Jul 28-
Aug 2
Jul 20-
Aug 4
Jul
20-26
Jul
19-23
Moderate
2005 --- --- --- --- --- --- --- --- --- ---
2006 Jul
4-5
Jul
4-10
Jul
12-26 Jul
7-10
Jul
7-12
Jul
12 & 21 Jun 29-
Jul 28
Jul
10-21
Jul
4-6
Light-
Heavy
2007 Jul
9-13
Jul
20-27
Jul 20-
Aug 8
Jul
9-20
Jul
18-27
Jul 27-
Aug 10
Jul 13-
Aug 10
Jul
8-23
Jul
16-19
Heavy
2008 Jul
10
Jul
14-16
Jul
14-30
Jul
11-14
Jul
14-16
Jul
18-25
Jul 8-
Aug 11
Jul
18-23
Jul
10-14
Heavy
2009 Jul
10-11
Jul
10-13
Jul 13-
Aug 5
Jul
10-13
Jul
17
Jul
17-27
Jul 10-
Aug 17
Jul
10-22
Jul
10 - ?
Nil-heavy
2010 Jul
8-12
Jul
12-14
Jul
13-26
Jul
9
Jul
9-14
Jul
12-23
Jul 9-
Aug 9
Jul
9-28
Jul
12 - ?
Heavy
2011 Jul
14
Jul
18
Jul
20
Jul
15
Jul
20
Jul
22
Aug
1
Jul
13
Jul
18
Nil-heavy
2012 Jul
4
Jul
9
Jul
13
Jul
6
Jul
13
Jul
18
Jul 6 -
Aug 10
Jul
11
Jul
11-16
Heavy
2013 Jul
8
Jul
8
Jul
15-22
Jul
12
Jul
15
Jul
17
--- --- Jul
11-12
Moderate
* PEI Shellfish Association and other grower information.
--- No information available
- 35 -
APPENDIX III
Maps Displaying Current Known Range of Invasive Species in PEI
- 36 -
Figure 18. Current known range of the clubbed tunicate, Styela clava.
- 37 -
Figure 19. Current known range of the golden star tunicate, Botryllus schlosseri.
- 38 -
Figure 20. Current known range of the vase tunicate, Ciona intestinalis.
- 39 -
Figure 21. Current known range of the violet tunicate, Botrylloides violaceus.
- 40 -
Figure 22. Current known range of the green crab, Carcinus maenas.
- 41 -
Figure 23. Current known range of the oyster thief, Codium fragile.
- 42 -
Figure 24. Current known range of the oyster drill, Urosalpinx cinerea.