pei oyster monitoring program - prince edward island · - i - acknowledgments the staff of the...

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 Division

P.O. Box 1180

548 Main Street

Montague, PEI

C0A 1R0

- i -

ACKNOWLEDGMENTS

The staff of the Oyster Monitoring Program, on behalf of the PEI Department of Fisheries,

Aquaculture and Rural Development, would like to thank the many people who assisted in the

delivery of the program. We would like to give special thanks and recognition of two employees

that have provided a long-term commitment to the oyster industry and specifically the oyster

monitoring program, Matt Smith and Paul Burleigh.

Additionally, the Department would like to thank all the growers who provided lines to hang

scallop shell collectors. We would like to extend our sincerest thanks to all of these people, as

well as the countless others over the history of this program, whose contributions have helped to

make this program a success.

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TABLE OF CONTENTS

ACKNOWLEDGMENTS ............................................................................................................. i

TABLE OF CONTENTS ............................................................................................................. ii

LIST OF FIGURES ..................................................................................................................... iii

LIST OF TABLES ....................................................................................................................... iv

INTRODUCTION......................................................................................................................... 1

METHODS .................................................................................................................................... 2 Larvae (Spat-fall Prediction) ...................................................................................................... 3

Spat-fall ....................................................................................................................................... 4 Water Quality .............................................................................................................................. 4

Tunicate Monitoring ................................................................................................................... 4

RESULTS ...................................................................................................................................... 5 Larvae (Spat-fall Prediction) ...................................................................................................... 5 Spat-fall ....................................................................................................................................... 5

Short-Term Collectors ............................................................................................................ 5 Long-Term Collectors ............................................................................................................. 6

Water Temperature ..................................................................................................................... 6

Tunicate Monitoring ................................................................................................................... 6

DISCUSSION .............................................................................................................................. 20 Factors to Consider in Timing Collector Deployment ............................................................. 20

Factors Affecting Oyster Set ..................................................................................................... 21 Limitations of the OMP ............................................................................................................. 21

APPENDIX I - Maps Showing Oyster and Spat Monitoring Sites ........................................ 22

APPENDIX II - Historical Spat Collection Data ..................................................................... 30

APPENDIX III - Maps Displaying Current Known Range of Invasive Species in PEI ....... 33

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LIST OF FIGURES

Figure 1. PEI Shellfish Association deploying collectors in the Bideford River. .......................... 1

Figure 2. PEI oyster landings and values from 1980 to 2011. ........................................................ 2

Figure 3. Sample collection sites for the 2012 Oyster Monitoring Program. ................................. 2

Figure 4. Oyster larvae, with foot extended, ready to set (365 µm). .............................................. 3

Figure 5. Oyster spat collectors ...................................................................................................... 4

Figure 6. Oyster collector lines in Gibb's Creek. ............................................................................ 6

Figure 7. Oyster Monitoring Sites in Bideford River: (1) Station, (2) Paugh’s Creek, (3) Old

Wharf and (4) Green Park. ............................................................................................................ 23

Figure 8. Oyster Monitoring Site 5: Foxley River and Site 6: Gibb’s Creek. .............................. 23

Figure 9. Oyster Monitoring Site 7: Enmore River and Site 8: Percival River. ........................... 24

Figure 10. Oyster Monitoring Site 9: Mill River. ......................................................................... 24

Figure 11. Oyster Monitoring Site 10: Kildare River. .................................................................. 25

Figure 12. Oyster Monitoring Site 11: Bentick Cove. .................................................................. 25

Figure 13. Oyster Monitoring Site 12: Grand River. .................................................................... 26

Figure 14. Oyster Monitoring Site 13: Bedeque Bay and Site 14: Wilmot River. ....................... 26

Figure 15. Oyster Monitoring Site 15: West River. ...................................................................... 27

Figure 16. Oyster Monitoring Site 16: North River. ..................................................................... 27

Figure 17. Oyster Monitoring in East River Site 17: Cranberry Wharf and Site 18: MacWilliams

Seafood. ........................................................................................................................................ 28

Figure 18. Oyster Monitoring Site 19: Vernon River and Site 20: Orwell River. ........................ 28

Figure 19. Oyster Monitoring Site 21: Pownal Bay. .................................................................... 29

Figure 20. Current known range of the clubbed tunicate, Styela clava. ....................................... 34

Figure 21. Current known range of the golden star tunicate, Botryllus schlosseri. ...................... 35

Figure 22. Current known range of the vase tunicate, Ciona intestinalis. .................................... 36

Figure 23. Current known range of the violet tunicate, Botrylloides violaceus. .......................... 37

Figure 24. Current known range of the green crab, Carcinus maenas. ........................................ 38

Figure 25. Current known range of the oyster thief, Codium fragile. .......................................... 39

Figure 26. Current known range of the oyster drill, Urosalpinx cinerea. .................................... 40

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LIST OF TABLES

Table 1. 2012 Oyster Monitoring data from Site 1: Bideford River - Station Site ......................... 7

Table 2. 2012 Oyster Monitoring data from Site 2: Bideford River - Paugh’s Creek .................... 8

Table 3. 2012 Oyster Monitoring data from Site 3: Bideford River - Old Wharf .......................... 9

Table 4. 2012 Oyster Monitoring data from Site 4: Bideford River - Green Park ....................... 10

Table 5. 2012 Oyster Monitoring data from Site 5: Foxley River and Site 6: Gibb’s Creek ....... 11

Table 6. 2012 Oyster Monitoring data from Site 7: Enmore River and Site 8: Percival River .... 12

Table 7. 2012 Oyster Monitoring data from Site 9: Mill River and Site 10: Kildare River ......... 13

Table 8. 2012 Oyster Monitoring data from Site 11: Bentick Cove and Site 12: Grand River .... 14

Table 9. 2012 Oyster Monitoring data from Site 13: Bedeque Bay and Site 14: Wilmot River .. 14

Table 10. 2012 Oyster Monitoring data from Site 15: West River and Site 16: North River ...... 15

Table 11. 2012 Oyster Monitoring data from East River for Site 17: Cranberry Wharf and Site

18: MacWilliams Seafood............................................................................................................. 16

Table 12. 2012 Oyster Monitoring data from Site 19: Vernon River and Site 20: Orwell River . 17

Table 13. 2012 Oyster Monitoring data from Site 21: Pownal Bay. ............................................ 18

Table 14. Summary of occurrence of oyster larvae > 250 μm at the sites in western PEI

monitored in 2012 ......................................................................................................................... 19

Table 15. Correlation of the presence of oyster larvae > 250 μm to oyster spat set on OMP

collectors and grower collectors in the Bideford River in 2012 ................................................... 19

Table 16. Correlation of the combined OMP larvae (> 250 μm) and spat data to grower

information in the Bideford River for the period 2001-2004 and 2006-2012 .............................. 31

Table 17. PEI Shellfish Association collector deployment dates and spat set results from 1990 –

2012............................................................................................................................................... 32

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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

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 (Figure 1). Information is

collected through the monitoring of the number and size of oyster larvae in water samples

collected from 21 sites throughout the province. Oyster collectors are also placed in the Bideford

River System to monitor the timing and amount of oyster spat set. Water temperature data is

collected from 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. PEI Shellfish Association deploying collectors in the Bideford River.

Since 2006, with the possibility of the clubbed tunicate, Styela clava, spreading to the Bideford

River from nearby March Water, tunicate monitoring was added to the OMP. The information

collected from monitoring for tunicates is to provide information to growers on the infestation

levels, primarily in the Bideford River.

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In 2011, the Island oyster industry (including aquaculture and the wild fishery) had landings of

5,913,310 lbs, with a landed value of $6,622,000 which was an increase of 451,310 lbs as

compared to 2010 (see Figure 2). Landings have been relatively stable since 2000, with some

fluctuations. Over the past four years some bottom leases have been converted to off-bottom

leases. Cultured production capacity is expected to continue increasing as a result of these new

lease conversions.

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Figure 2. PEI oyster landings and values from 1980 to 2011.

METHODS

Data from 21 sites in 16 river systems was collected for the OMP in 2012 (Figure 3). Staff based

in Charlottetown collected and evaluated data from sites in East River (sites are named

Cranberry Wharf and MacWilliams Seafood), North River, West River, Pownal Bay, Orwell

River and Vernon River. Staff based in the western portion of PEI monitored four sites in

Bideford River (sites are named Station, Paugh’s Creek, Old Wharf and Green Park), and

additional sites in Foxley River (sites are named Lot 10 and Gibbs Creek), Enmore River,

Percival River, Mill River, Kildare River, Grand River, Bentick Cove, Bedeque Bay and Wilmot

River. Maps displaying the locations of the 21 sites are found in Appendix I.

Figure 3. Sample collection sites for the 2012 Oyster Monitoring Program.

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Larvae (Spat-fall Prediction)

To ensure that the oyster spawning and the first appearance of oyster larvae would not be missed,

adult oysters were frequently opened and the gonads examined to monitor for the first release of

eggs and sperm. This monitoring began in early June in the Bideford River, as it is historically

one of the sites where spawning occurs first. Once the release of eggs and sperm was observed,

tows for oyster larvae were initiated.

At all of the Oyster Monitoring Program sites, 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. The

sampling period was extended from late August until late September in the Vernon and Orwell

Rivers. This sampling was done to determine when oysters were finished setting, so growers

could determine when to treat their adult oysters to kill and remove the oyster spat that had set on

them.

Water samples were obtained by towing a 2.5 metre (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 5

minutes. The 63 µm net should 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 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 larvae in the

subsample was measured and its size recorded, for Western sites only (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. 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).

- 4 -

Spat-fall

The amount of oyster recruitment was monitored at the “Station” site in the Bideford River using

oyster spat collectors. The spat collectors consisted of a length of galvanized wire with one

scallop shell (scallop shells are a very good substrate for the collection of oyster spat) placed at

30 cm (one foot), one at 60 cm (three feet), and one at 90 cm (five feet) along the wire. 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. Two collectors were placed on a long

line every two to three days (normally Monday, Wednesday and Friday). One of these collectors

was recovered when the next two collectors were deployed (short-term collector – STC) and the

second collector remained in the water for approximately three weeks (long-term collector –

LTC). The oyster spat on the top and bottom of each shell was counted using a dissecting

microscope. Long-term collectors were not left out for the entire summer, as spat would have

grown over each other or been covered and killed by fouling, making it impossible to get an

accurate count of the oyster spat. No treatment was performed on any of the department scallop

shell collectors to control fouling.

Figure 5. Oyster spat collectors

Water Quality

Water Temperature was measured at all the sites 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 the rack and bag system).

As much of the oyster seed collected in the Bideford River system is moved to leases in other

areas or public beds for enhancement purposes, there is a possibility that the tunicates could set

on the oyster collectors and then spread to other areas with the transfer of oyster spat from the

- 5 -

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 for tunicate

densities.

RESULTS

Larvae (Spat-fall Prediction)

Tables 1 – 13 display data describing the concentration and size ranges of larvae from water

samples collected on different sampling dates at each of the sites monitored. To help clarify the

timing of the spat set the tables showing data from the western PEI sites contain the actual

number of larvae present and the number of larvae > 250 μm; however, because of high

sedimentation in the water column in the eastern sites only a range (low, medium, high, and very

high) has been reported. Oyster larvae that are 250 μm are almost ready to set and will reach a

setting size of 300 – 365 μm in approximately 1-3 days.

The first observation of oyster larvae was in late June. Larvae > 250 μm were first observed at

all four of the Bideford sites between July 2nd

and July 9th

and between July 5th

and July 20th

at

other sites. The first high larvae numbers were observed between July 9th

and July 11th

at the

Bideford Sites and between July 15th

and 28th

at the other sites. This data is summarized in

Table 14.

Spat-fall

The spat set results from the OMP oyster spat collectors allows for correlation between larvae

numbers observed in the water samples and the amount of spat set for any particular time. Table

1 displays the spat set results from the ‘Station’ site in the Bideford River. The table containing

the data from the ‘Station’ site displays information for both short-term collectors (STC) and

long-term collectors (LTC).

While the number of spat on the top and bottom of 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 an area 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 15 contains data comparing the sample collection date, the number of larvae > 250

μm present, the number of spat set on STC, the number of spat set on LTC and grower results 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 6th

.

The first appearance of high numbers of spat on STC was on July 13th

, or nine days after the first

observation of larvae greater than 250 μm. The peak number of spat on STC was July 18th

, or

fourteen days following the initial observation of larvae greater than 250 μm.

- 6 -

Long-Term Collectors

The long-term collectors (LTC) were deployed weekly between July 6th

and August 10th

. The

collectors were deployed approximately every 2-3 days and remained in the water until they

were brought in approximately three weeks later. In an attempt to get a good indication of the

number of spat that set over a period of time, the collectors were retrieved before the spat started

to get so large that they would cover each other and before fouling organisms, such as sea

squirts, started to cover the spat. As a result, the collectors were not susceptible to the same

crowding and fouling that grower collectors were and this may have resulted in higher numbers

of spat on the LTC as compared to the grower collectors. The data displayed in Table 1 indicates

that there were good oyster sets on the LTC deployed at the ‘Station’ site in the Bideford River

between July 6th

and July 20th

(LTC that were deployed early had a chance to collect spat over a

long period of time if they remained clean).

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. The colonial tunicates continue to be

found in increasing abundance in Cascumpec and have also been detected in the Bideford River

(2011) In 2012, clubbed tunicate was also newly identified in Grand River and Souris River and

colonial tunicates (golden star and violet) were newly identified in North Rustico, South Rustico

and Southwest River. 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. Known range of the green crab, oyster

thief and oyster drill is also included in Appendix III.

Figure 6. Oyster collector lines in Gibb's Creek.

http://www.gov.pe.ca/fard

- 7 -

Table 1. 2012 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 LTC

June 19 L-3 90-130 0 19.0 --- ---

June 22 M-15 70-120 0 20.4 --- ---

June 25 L-3 70-80 0 19.2 --- ---

June 29 M-6 80-120 0 20.4 --- ---

July 2 H-35 90-110 0 21.7 --- ---

July 3 VH-103 80-170 0 21.8 --- ---

July 4 H-73 80-330 2 23.0 0 ---

July 6 VH-121 90-350 16 22.7 4 8084

July 9 VH-210 90-370 98 22.1 19 7448

July 11 VH-1228 100-370 504 21.4 13 8302

July 13 VH-1430 110-370 1226 22.3 361 2438

July 16 VH-812 120-370 696 22.7 236 5204

July 18 VH-221 90-370 182 23.3 955 1153

July 20 VH-473 90-370 369 21.8 632 480

July 23 VH- 266 80-370 219 23.5 5 87

July 25 H-78 90-350 57 23.2 26 119

July 27 H-67 80-340 32 24.0 21 7

July 30 M-6 120-350 3 24.9 1 4

August 1 M-17 100-350 7 25.3 2 1

August 3 M-6 110-350 1 23.9 1 1

August 6 L-5 160-200 0 25.9 0 0

August 8 M-8 70-300 1 26.1 0 0

August 10 L-1 80 0 27.4 0 0

August 13 0 --- 0 25.1 0 ---

August 16 M-6 70-90 0 25.5 0 ---

August 20 L-1 70 0 24.0 0 ---

August 23 0 --- 0 24.6 --- ---

250 micron (μm) oyster larvae take 1 to 3 days to reach a setting size of 365 μm.

--- No information available.

* Scallop shell collectors were deployed on the dates shown.

** Larvae numbers were reported as: 1 - 5 larvae as low, 6 - 19 as medium, 20 - 99 as high and ≥ 100 as very high.

- 8 -

Table 2. 2012 Oyster Monitoring data from Site 2: Bideford River - Paugh’s Creek

Date

Paugh’s Creek Larvae Data Water

Temp.

(°C)



(μm) # >250 μm STC LTC

June 19 L-2 80-90 0 20.0 --- ---

June 22 M-13 80-110 0 20.4 --- ---

June 25 L-3 80-110 0 19.2 --- ---

June 29 M-9 70 0 20.6 --- ---

July 2 H-21 70-320 2 22.2 --- ---

July 4 VH-118 90-350 17 23.2 --- ---

July 6 H-56 100-350 9 22.7 --- ---

July 9 H-68 100-320 10 22.2 --- ---

July 11 H-47 150-370 30 21.4 --- ---

July 13 VH-450 110-370 398 22.9 --- ---

July 18 VH-867 150-360 759 24 --- ---

July 20 VH-428 100-360 428 21.6 --- ---

July 23 VH-314 100-360 248 24.1 --- ---

July 25 H-54 80-360 41 23.4 --- ---

July 27 VH-115 100-340 79 24.8 --- ---

July 30 L-2 80-120 0 25.1 --- ---

August 1 M-10 110-320 3 26.0 --- ---

August 3 L-2 150-300 2 24.0 --- ---

August 6 L-1 120 0 26.5 --- ---

August 8 L-1 280 1 26.6 --- ---

August 10 0 --- 0 27.8 --- ---

August 13 L-3 70-120 0 25.1 --- ---

August 16 L-4 80-190 0 25.5 --- ---

August 20 0 --- 0 24.5 --- ---

August 23 L-2 80-370 1 25.1 --- ---


--- No information available



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Table 3. 2012 Oyster Monitoring data from Site 3: Bideford River - Old Wharf

Date

Old Wharf Larvae Data Water

Temp.

(°C)



(μm) # >250 μm STC LTC

June 25 L-1 80 0 18.8 --- ---

June 29 L-4 80 0 20.1 --- ---

July 2 M-11 80-100 0 21.7 --- ---

July 4 M-11 80-190 0 22.5 --- ---

July 6 M-10 100-180 0 22.0 --- ---

July 9 VH-125 100-370 20 22.4 --- ---

July 11 VH-308 170-350 96 21.3 --- ---

July 13 VH-714 150-350 656 22.3 --- ---

July 18 VH-298 200-360 287 22.9 --- ---

July 20 VH-211 90-370 171 21.8 --- ---

July 23 VH-435 90-360 348 23.5 --- ---

July 25 H-26 110-350 11 23.1 --- ---

July 27 H-57 70-360 32 23.8 --- ---

July 30 H-35 70-350 11 24.3 --- ---

August 1 H-32 80-350 16 25.0 --- ---

August 3 H-27 100-360 14 23.6 --- ---

August 6 M-6 110-360 11 25.4 --- ---

August 8 M-9 80-310 1 25.8 --- ---

August 10 M-11 80-330 9 26.8 --- ---

August 13 L-1 80 0 24.9 --- ---

August 16 M-8 70-80 0 25.0 --- ---

August 20 L-1 70 0 23.8 --- ---

August 23 L-3 100-200 0 24.9 --- ---





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Table 4. 2012 Oyster Monitoring data from Site 4: Bideford River - Green Park

Date Green Park Larvae Data Water

Temp.

(°C)


Total #** Size

Range (μm)

# >250 μm STC LTC

June 29 M-7 10-110 0 19.4 --- ---

July 2 M-10 80-130 0 22.2 --- ---

July 4 M-14 80-150 0 22.3 --- ---

July 6 H-44 90-230 0 21.5 --- ---

July 9 VH-231 100-370 85 22.1 --- ---

July 11 VH-158 90-370 72 21.4 --- ---

July 13 VH-430 170-370 392 22.3 --- ---

July 18 VH-454 200-360 438 22.9 --- ---

July 20 VH-143 80-370 119 22.1 --- ---

July 23 VH-162 90-360 139 23.0 --- ---

July 25 VH-104 100-360 90 23.0 --- ---

July 27 H-58 70-350 23 23.9 --- ---

July 30 H-35 70-350 112 24.3 --- ---

August 1 H-23 110-350 17 24.1 --- ---

August 3 H-41 100-350 18 23.4 --- ---

August 6 M-13 110-350 9 25.1 --- ---

August 8 M-13 80-240 0 26.9 --- ---

August 10 M-19 70-350 4 26.5 --- ---

August 13 M-7 150-340 6 24.6 --- ---

August 16 L-5 70-80 0 25.0 --- ---

August 20 M-6 70-140 0 23.8 --- ---

August 23 0 --- 0 24.5 --- ---


— No information available.

* Scallop shell collectors were deployed on the dates shown, except *** deployed July 13.


- 11 -

Table 5. 2012 Oyster Monitoring data from Site 5: Foxley River and Site 6: Gibb’s Creek

Date

Foxley River Larvae Data Gibb’s Creek Larvae Data

Total #* Size Range

(μm)

# > 250

μm

Water

Temp.

(°C)

Total #* Size Range

(μm)

# > 250

μm

Water

Temp

(°C)

June 26 L-3 80-130 0 20.4 L-2 80-100 0 19.9

June 28 L-3 70 0 21.0 L-3 70 0 20.8

July 3 H-86 80-110 0 23.9 H-58 70-110 0 23.6

July 5 VH-205 80-130 0 23.4 H-58 70-150 0 22.6

July 9 H-88 80-300 8 22.4 VH-223 80-300 6 22.8

July 11 H-59 140-330 31 22.1 VH-208 110-310 74 22.1

July 13 VH-304 90-360 261 22.9 H-69 120-340 31 22.8

July 16 VH-184 80-360 152 23.1 VH-308 110-370 279 22.0

July 18 VH-314 80-350 227 22.5 VH-552 110-360 270 21.7

July 20 VH-204 80-350 113 21.7 VH-402 120-360 251 20.4

July 23 M-12 250-350 12 --- VH-278 80-360 149 ---

July 26 L-1 350 1 22.0 VH-238 90-370 170 21.9

July 30 M-18 70-340 5 23.8 H-47 70-190 0 22.9

August 2 H-28 70-320 1 24.4 H-61 80-350 24 24.7

August 6 H-27 70-300 6 25.3 H-66 70-250 1 25.7

August 10 H-33 70-170 0 25.9 H-32 70-230 0 25.5

August 21 H-22 70-80 0 24.8 M-15 70-140 0 24.9



* 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 6. 2012 Oyster Monitoring data from Site 7: Enmore River and Site 8: Percival River Date

Enmore River Larvae Data Percival River Larvae Data

Total #* Size

Range

(μm)

# > 250 μm Water

Temp.

(°C)

Total #* Size

Range

(μm)

# > 250 μm Water

Temp.

(°C)

June 25 --- --- --- --- M-8 70-90 0 18.7

June 28 L-5 70-100 0 21.1 H-22 70-100 0 22.0

July 3 VH-999+ 80-190 0 22.8 VH-300 80-100 0 22.6

July 5 VH-999+ 90-170 0 22.9 VH-2170 70-150 0 23.3

July 9 VH-1740 70-250 40 22.4 VH-999+ 110-230 0 23.0

July 12 H-80 130-350 9 24.5 VH-1235 120-300 430 23.2

July 16 VH-1155 170-370 1023 23.4 VH-646 180-370 513 22.8

July 19 VH-1674 290-360 1674 23.2 VH-2388 190-370 1826 23.2

July 23 VH-103 70-350 92 --- VH-1762 230-350 1566 ---

July 26 H-44 90-360 26 24.5 VH-956 150-350 900 23.9

July 30 L-1 320 1 25.3 VH-168 80-306 148 24.9




- 13 -

Table 7. 2012 Oyster Monitoring data from Site 9: Mill River and Site 10: Kildare River

Date

Mill River Larvae Data Kildare River Larvae Data

Total #* Size Range

(μm)

# > 250

μm

Water

Temp.

(°C)

Total #* Size Range

(μm) # > 250μm

Water

Temp.

(°C)

June 26 M-12 80-100 0 19.4 --- --- --- ---

June 28 M-19 70-100 0 20.1 --- --- --- ---

July 3 VH-166 70-210 0 22.5 --- --- --- ---

July 5 VH-109 80-300 17 22.6 --- --- --- ---

July 9 H-69 70-200 0 22.3 L-2 80-90 0 21.1

July 16 H-60 110-360 55 22.5 --- --- --- ---

July 20 H-31 80-350 19 23.7 H-71 180-320 61 22.3

July 23 VH-103 80-350 44 --- --- --- --- ---

July 26 H-82 90-350 23 24.1 --- --- --- ---

August 2 VH-100 70-360 30 24.2 --- --- --- ---

August 6 H-79 70-350 25 25.0 --- --- --- ---




- 14 -

Table 8. 2012 Oyster Monitoring data from Site 11: Bentick Cove and Site 12: Grand River

Date

Bentick Cove Larvae Data Grand River Larvae Data

Total #* Size Range

(μm)

# > 250

μm

Water

Temp.

(°C)

Total #* Size Range

(μm) # > 250μm

Water

Temp.

(°C)

June 26 M-6 80-90 0 20.5 L-4 80-90 0 19.4

June 28 M-9 70 0 21.0 H-27 70 0 20.1

July 3 L-3 70-80 0 21.2 M-15 80-210 0 22.3

July 5 H-24 80-180 0 22.6 H-71 80-220 0 23.7

July 9 H-92 70-350 25 21.3 H-66 100-350 9 21.8

July 12 H-35 130-350 8 22.5 H-72 80-370 41 23.2

July 16 H-20 130-350 10 22.7 VH-318 170-370 262 23.9

July 19 H-92 170-360 78 22.8 VH-771 220-310 746 ---

July 23 H-54 130-360 42 --- H-51 200-360 49 23.0

July 26 VH-119 200-350 109 23.6 VH-128 170-360 111 23.9




Table 9. 2012 Oyster Monitoring data from Site 13: Bedeque Bay and Site 14: Wilmot River

Date

Bedeque Bay Larvae Data Wilmot River Larvae Data

Total #* Size Range

(μm)

# >

250μm

Water

Temp.

(°C)

Total #* Size Range

(μm)

# >

250μm

Water

Temp.

(°C)

June 26 0 --- 0 18.9 0 --- 0 18.7

July 12 VH-1088 80-200 0 21.6 VH-163 80-210 0 22.2

July 16 VH-292 90-320 192 22.1 VH-141 100-320 67 22.8

July 26 H-71 80-350 40 23.5 H-61 80-360 57 23.8




- 15 -

Table 10. 2012 Oyster Monitoring data from Site 15: West River and Site 16: North River

Date

West River Larvae Data North River Larvae Data

Total #* Size Range (μm) Water

Temp. (°C) Total #* Size Range (μm)

Water

Temp. (°C)

June 25 M 80-85 17.6 L 80 17.3

June 27 L 75-80 18.1 L 80-85 18.0

June 29 H 75-110 18.4 --- --- ---

July 3 L 80-85 20.7 H 80-115 20.3

July 6 H 90-175 21.6 --- --- ---

July 9 M 100-230 21.2 M 100-190 20.6

July 11 H 95-210 20.4 0 --- 19.7

July 16 M 95-300 20.3 H 80-260 20.7

July 18 H 90-340 20.7 M 80-160 21.0

July 20 M 80-320 20.5 M 100-320 19.5

July 23 M 85-290 21.3 M 75-250 21.3

July 25 M 85-325 20.6 L 160 22.0

July 27 M 85-320 21.7 --- --- ---

July 30 L 110-120 21.6 --- --- ---

August 1 H 75-350 22.0 --- --- ---

August 3 M 110-310 21.2 --- --- ---

August 8 L 120-230 23.9 L 120-320 23.9

August 14 M 140-340 23.6 --- --- ---



* Larvae numbers were reported as: L = low (1 - 5 larvae); M = medium (6 – 19 larvae); H = high (20 - 99 larvae);

and VH = very high (≥ 100 larvae).

- 16 -

Table 11. 2012 Oyster Monitoring data from East River for Site 17: Cranberry Wharf and Site

18: MacWilliams Seafood

Date

East River

Cranberry Wharf Larvae Data MacWilliams Seafood Larvae Data

Total #* Size Range (μm) Water

Temp. (°C) Total #* Size Range (μm)

Water

Temp. (°C)

June 25 H 75-85 18.9 H 70-80 18.8

June 27 L 75-90 19.2 M 75-90 19.0

June 29 L 80-85 20.0 M 75-100 19.3

July 3 H 70-180 23.4 H 75-130 22.8

July 6 H 100-180 23.1 H 100-200 22.4

July 9 L 110-300 22.3 M 140-230 21.7

July 11 0 --- 21.9 H 90-310 22.0

July 13 M 80-250 21.8 M 90-260 22.0

July 16 H 75-330 22.0 H 80-350 21.9

July 18 VH 80-340 22.4 VH 75-335 22.0

July 20 H 80-330 21.9 H 80-360 21.4

July 23 M 90-160 22.9 H 80-320 22.7

July 25 L 180-210 21.9 H 80-330 21.5

July 27 M 75-280 21.3 M 80-320 21.3

July 30 H 100-345 22.8 M 90-325 22.7

August 1 M 120-335 23.0 H 100-340 22.8

August 3 L 80-120 22.0 L 110-330 21.0

August 8 L 90-325 25.5 M 110-330 25.0

August14 0 --- 23.3 M 110-330 24.2





- 17 -

Table 12. 2012 Oyster Monitoring data from Site 19: Vernon River and Site 20: Orwell River

Date

Vernon River Larvae Data Orwell River Larvae Data

Total # * Size Range

(μm)

Water

Temp. (°C) Total # * Size Range (μm)

Water

Temp. (°C)

June 25 M 70-80 19.3 M 70-75 17.9

June 27 0 --- 19.5 H 70-110 18.5

June 29 M 85-110 20.2 M 80-85 18.6

July 3 H 70-120 23.9 H 75-130 20.6

July 6 H 85-130 21.8 H 90-110 20.1

July 9 H 90-210 21.9 H 85-205 20.9

July 11 L 85-230 21.7 M 100-240 21.5

July 13 H 75-260 22.0 H 85-230 21.6

July 16 H 100-340 21.5 H 90-320 20.7

July 18 H 80-340 21.0 H 80-340 20.1

July 20 H 80-350 21.4 H 80-340 20.6

July 23 M 170-310 21.9 H 85-310 21.5

July 25 L 120-180 21.4 H 180-325 21.3

July 27 L 330 22.7 H 120-330 22.1

July 30 M 120-360 22.8 M 100-340 21.8

August 1 H 80-330 22.7 H 85-340 21.9

August 3 H 90-350 22.0 H 75-345 21.5

August 8 M 120-280 24.2 H 100-340 24.0

August14 H 110-330 24.5 H 100-360 23.9





- 18 -

Table 13. 2012 Oyster Monitoring data from Site 21: Pownal Bay.

Date Pownal Bay Larvae Data

Total #* Size Range (μm) Water Temp. (°C)

June 29 L 75-80 21.0

July 4 H 85-135 21.2

July 6 H 90-170 21.7

Jul 11 H 140-240 21.6

July 16 H 120-330 21.8

August 1 H 75-345 23.1


— No information available.



- 19 -

Table 14. Summary of occurrence of oyster larvae > 250 μm at the sites in western PEI

monitored in 2012

Site

First Observation of Larvae > 250μm

1st

Observation 1

st Medium # 1

st High # Peak #’s

Station July 4 July 6 July 9 July 13

Paugh’s Creek July 2 July 4 July 11 July 18

Old Wharf July 9 July 9 July 9 July 13

Green Park July 9 July 9 July 9 July 18

Mill River July 5 July 5 July 16 July 16

Kildare River July 20 July 20 July 20 July 20

Foxley River July 9 July 9 July 11 July 13

Gibb’s Creek July 9 July 9 July 11 July 16

Enmore River July 9 July 9 July 9 July 19

Percival River July 12 July 12 July 12 July 19

Bentick Cove July 9 July 9 July 9 July 26

Grand River July 9 July 9 July 12 July 19

Bedeque Bay July 16 July 16 July 16 July 16

Wilmot River July 16 July 16 July 16 July 16

Table 15. Correlation of the presence of oyster larvae > 250 μm to oyster spat set on OMP

collectors and grower collectors in the Bideford River in 2012

Site

Larvae > 250μm OMP Collectors

Grower Collectors * STC LTC

1st

Observation

1st

High

#’s

1st High #’s Peak #’s Peak #’s Deployed Spat Set

Station July 4 July 9 July 13 July 18 July 11 July 13 Heavy

* PEI Shellfish Association and other grower information.

- 20 -

DISCUSSION

Factors to Consider in Timing Collector Deployment

Oyster growers have two types of information available to assist them in determining when to

deploy oyster collectors - historical information and current information. Historical information

is available from various sources on collector deployment dates from previous years. Current

information on the number and size of oyster larvae and spat set results are available through the

Oyster Monitoring Program phone information system.

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-

2012 is contained in Table 16 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

and as late as July 29th

. 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 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.

Table 15 summarizes the spat set information for the Bideford River Station site in relation to the

first appearance of 250 μm larvae and the 1st high number of 250 μm larvae observed in the

water samples. The information presented in this table indicates that collectors deployed at the

first appearance of 250 μm larvae have achieved a good set. The timing of the peak set observed

on short-term collectors (STC) and the set observed on the long-term collectors (LTC) suggests

collectors may have achieved an acceptable set if deployed when the first high numbers of larvae

> 250 μm were reported.

On average, grower collectors deployed by 5 – 7 days after the first 250 μm larvae 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 sets on the LTC

(collectors left out, 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 of 250 μm.

- 21 -

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, such as the following:

There were low numbers of setting size larvae.

There were 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.

There were two distinct sets and the collectors were not treated for fouling to collect the

second set.

There was a good set, but the collectors were not treated with lime and the spat were

killed by predators (starfish) or by growth of fouling organisms (bryozoa, sea squirts,

etc.).

In 2012, anecdotal reports from oyster growers indicate that this was a good year for oyster set

and department observations indicated good set in all collection areas. There were no major

problems caused by fouling organisms and predators in the Bideford River; however, sea squirts

caused enough fouling on collectors to require aquaculturalists to apply two treatments to some

of the collectors. The oyster set in East River and Vernon/Orwell Rivers was good; however, the

set in these areas appeared to be later in comparison to the western sites. As well, barnacle set

was a challenge this year in some areas along with an abundant population of sea squirts.

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 when tides

may be high or low and tidal currents ebbing or flooding. 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. Current and idling speeds will affect the amount of water that is sampled.

These and other factors can cause variable 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 tows could mean that the first 250 μm larvae may be present 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. In this report the analysis of success of spat collection

over time is based solely on the larvae and collector data observed through the OMP and on

grower results obtained through conversations with individual growers. If you have any

questions about the data contained in this report you can contact the Department at (902) 838-

0910, or by e-mailing Jarrod Gunn McQuillan at [email protected].

- 22 -

APPENDIX I

Maps Showing Oyster and Spat Monitoring Sites

- 23 -

Figure 7. Oyster Monitoring Sites in Bideford River: (1) Station, (2) Paugh’s Creek, (3) Old Wharf and (4)

Green Park.

Figure 8. Oyster Monitoring Site 5: Foxley River and Site 6: Gibb’s Creek.

- 24 -

Figure 9. Oyster Monitoring Site 7: Enmore River and Site 8: Percival River.

Figure 10. Oyster Monitoring Site 9: Mill River.

- 25 -

Figure 11. Oyster Monitoring Site 10: Kildare River.

Figure 12. Oyster Monitoring Site 11: Bentick Cove.

- 26 -

Figure 13. Oyster Monitoring Site 12: Grand River.

Figure 14. Oyster Monitoring Site 13: Bedeque Bay and Site 14: Wilmot River.

- 27 -

Figure 15. Oyster Monitoring Site 15: West River.

Figure 16. Oyster Monitoring Site 16: North River.

- 28 -

Figure 17. Oyster Monitoring in East River Site 17: Cranberry Wharf and Site 18: MacWilliams Seafood.

Figure 18. Oyster Monitoring Site 19: Vernon River and Site 20: Orwell River.

- 29 -

Figure 19. Oyster Monitoring Site 21: Pownal Bay.

- 30 -

APPENDIX II

Historical Spat Collection Data

- 31 -

Table 16. Correlation of the combined OMP larvae (> 250 μm) and spat data to grower

information in the Bideford River for the period 2001-2004 and 2006-2012

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

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

* PEI Shellfish Association and other grower information.

- 32 -

Table 17. PEI Shellfish Association collector deployment dates and spat set results from

1990 – 2012

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

- 33 -

APPENDIX III

Maps Displaying Current Known Range of Invasive Species in PEI

- 34 -

Figure 20. Current known range of the clubbed tunicate, Styela clava.

- 35 -

Figure 21. Current known range of the golden star tunicate, Botryllus schlosseri.

- 36 -

Figure 22. Current known range of the vase tunicate, Ciona intestinalis.

- 37 -

Figure 23. Current known range of the violet tunicate, Botrylloides violaceus.

- 38 -

Figure 24. Current known range of the green crab, Carcinus maenas.

- 39 -

Figure 25. Current known range of the oyster thief, Codium fragile.

- 40 -

Figure 26. Current known range of the oyster drill, Urosalpinx cinerea.

pei oyster monitoring program - prince edward island · - i - acknowledgments the staff of the...

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