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CAWTHRON INSTITUTE | REPORT NO. 3275 MARCH 2019

ANNUAL ENVIRONMENTAL MONITORING AT THE FORSYTH BAY, WAIHINAU BAY, OTANERAU BAY AND RUAKAKA BAY SALMON FARMS 2018

REPORT NO. 3275


ANNUAL ENVIRONMENTAL MONITORING AT THE FORSYTH BAY, WAIHINAU BAY, OTANERAU BAY AND RUAKAKA BAY SALMON FARMS 2018

LAUREN FLETCHER, HOLLY BENNETT, DEANNA ELVINES, EMILY

MCGRATH, EMMA NEWCOMBE

Prepared for The New Zealand King Salmon Co. Ltd.

CAWTHRON INSTITUTE 98 Halifax Street East, Nelson 7010 | Private Bag 2, Nelson 7042 | New Zealand Ph. +64 3 548 2319 | Fax. +64 3 546 9464 www.cawthron.org.nz

REVIEWED BY: Anna Berthelsen

APPROVED FOR RELEASE BY: Grant Hopkins

ISSUE DATE: 01 March 2019

RECOMMENDED CITATION: Fletcher L, Bennett H, Elvines D, McGrath E, Newcombe E 2019. Annual environmental monitoring at the Forsyth Bay, Waihinau Bay, Otanerau Bay and Ruakaka Bay salmon farms 2018. Prepared for The New Zealand King Salmon Co. Ltd. Cawthron Report No. 3275. 56 p. plus appendices.

© COPYRIGHT: This publication must not be reproduced or distributed, electronically or otherwise, in whole or in part without the written permission of the Copyright Holder, which is the party that commissioned the report.


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EXECUTIVE SUMMARY

This report presents the 2018 annual environmental monitoring results for the New

Zealand King Salmon Company Limited low-flow farm sites situated in Forsyth Bay,

Waihinau Bay, Otanerau Bay and Ruakaka Bay.

Monitoring assessed depositional effects on soft-sediment and inshore habitats, as

well as effects on some aspects of water quality. Soft-sediment habitats were

assessed for both seabed enrichment and copper and zinc concentrations.

Enrichment effects were measured against ecological quality standards (EQS) set out

in the relevant resource consent. Inshore habitats were qualitatively assessed for

general health with respect to signs of excessive deposition, nutrient enrichment and

other obvious changes in visual characteristics over time. Results of the water column

monitoring were used to quantify the effect of individual farms on the surrounding

near-field environment.

All farms were compliant with the consented EQS except for the 150 m station at

Ruakaka Bay. An overview of the results of environmental monitoring at specific farm

sites and associated recommendations is provided below.

Forsyth Bay

There was considerable improvement in seabed enrichment at the Pen 2 station at

the centre of the Forsyth Bay farm (ES 3.2 ± 0.3 compared with ES 5.2 ± 0.3, October

2017). Macrofaunal indicators showed marked recovery; however, organic matter and

sediment chemistry remain impacted. Potentially bio-available zinc concentrations

have increased dramatically since the previous monitoring round and continue to

exceed the ISQG-High threshold for probable biological effects. We recommend

additional monitoring at the Forsyth site in response to zinc levels, to understand the

mechanism for this increasing contamination. Further, we do not recommend that the

Forsyth site is restocked until these issues are resolved due to the compromised

ability of the site to assimilate organic waste. Water column measurements did not

indicate impacts of farming activities due to enrichment-related processes.

Waihinau Bay

Very high levels of seabed enrichment were recorded adjacent to the net pens at the

Waihinau Bay farm, with associated high abundances of opportunistic taxa (e.g.

capitellid and nematode worms) present in all samples. There are no environmental

quality standards specified in the resource consent, and monitoring at this site is

conducted voluntarily. Potentially bio-available zinc concentrations were moderately

high (exceeding ISQG-Low at one pen station). Water column measurements did not

indicate impacts of farming activities due to enrichment-related processes.

MARCH 2019 REPORT NO. 3275 | CAWTHRON INSTITUTE

Otanerau Bay

Seabed enrichment levels adjacent to the net pens at the Otanerau Bay farm were

very high, however they were compliant with the assumed ES in the resource

consent. Macrofaunal indicators suggest the site is deteriorating beyond ‘peak-of-

opportunist’ levels, with reduced animal abundances and low taxa richness. It is

recommended that the archive samples are processed for greater certainty around

localised enrichment conditions at this station. Water column measurements indicated

localised impacts of farming activities due to enrichment-related processes.

Decreases in water column DO and increases in turbidity were recorded at the pen

stations, and to a lesser extent at the 50 m station.

Ruakaka Bay

Seabed enrichment levels adjacent to the net pens at the Ruakaka Bay farm have

decreased since the last assessment, largely driven by improvements in sediment

chemistry. Enrichment levels were within the assumed ES under the present resource

consent conditions. There has been a deterioration in seabed enrichment at the outer

zone (150 m), and this station exceeded the assumed ES allowable under the

resource consent. This result was largely driven by a high proportion of opportunistic

taxa (mainly dorvilleid worms) within two of the replicate samples. It should be noted

that the far-field control site also had an elevated Enrichment Stage score in the

current monitoring round and some degree of inter-annual variation is to be expected.

It is recommended that feed input at the Ruakaka Bay farm remains at current (or

lower) levels to allow further recovery at the pen and outer stations. Water column

measurements did not indicate impacts of farming activities due to enrichment-related

processes.


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TABLE OF CONTENTS

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

2. COMPLIANCE FRAMEWORK ....................................................................................... 3

2.1. Enrichment ..................................................................................................................................................... 3

2.2. Copper and zinc ............................................................................................................................................. 4

3. FORSYTH BAY .............................................................................................................. 5

3.1. Site details and history of feed usage ............................................................................................................. 5

3.2. Sampling overview ......................................................................................................................................... 6

3.3. Soft-sediment habitat description ................................................................................................................... 7

3.4. Assessment of seabed enrichment ................................................................................................................. 8

3.5. Copper and zinc concentrations ................................................................................................................... 12

3.6. Inshore habitats ............................................................................................................................................ 14

3.7. Water column ............................................................................................................................................... 15

4. WAIHINAU BAY ............................................................................................................16

4.1. Site details and history of feed usage ........................................................................................................... 16

4.2. Sampling overview ....................................................................................................................................... 18

4.3. Soft-sediment habitat description ................................................................................................................. 19

4.4. Assessment of seabed enrichment ............................................................................................................... 21



4.7. Water column ............................................................................................................................................... 26

5. OTANERAU BAY ..........................................................................................................28







5.7. Water column ............................................................................................................................................... 37

6. RUAKAKA BAY .............................................................................................................39







6.7. Water column ............................................................................................................................................... 48

7. SUMMARY AND RECOMMENDATIONS FOR ALL SITES ...........................................50

7.1. Forsyth Bay .................................................................................................................................................. 50

7.2. Waihinau Bay ............................................................................................................................................... 51

7.3. Otanerau Bay ............................................................................................................................................... 52

7.4. Ruakaka Bay ................................................................................................................................................ 52

8. ACKNOWLEDGEMENTS .............................................................................................55


9. REFERENCES .............................................................................................................55

10. APPENDICES ...............................................................................................................56

LIST OF FIGURES

Figure 1. Map of the Marlborough Sounds area indicating the location of the Forsyth Bay, Waihinau Bay, Otanerau Bay and Ruakaka Bay farm sites (red dots) and other NZ King Salmon consented farm sites (black dots). ................................................................. 1

Figure 2. Operational state of the Forsyth Bay (FOR) farm (occupied vs. fallowed) from 1994–2017. ................................................................................................................................... 5

Figure 3. Annual feed inputs (December through November) at the Forsyth Bay (FOR) salmon farm, 2005-2017. ................................................................................................................. 5

Figure 4. Soft-sediment sampling locations at the Forsyth Bay (FOR) site. The Pen 1 station was not sampled in Oct 2018. ............................................................................................. 6

Figure 5. Representative images of the seafloor at each of the Forsyth Bay (FOR) salmon farm monitoring stations, October 2018. ..................................................................................... 7

Figure 6. Representative sediment grab and core photos of the pen and control station sampling sites at the Forsyth Bay (FOR) farm, October 2018. .......................................................... 9

Figure 7. Sediment organic matter (% ash-free dry weight; AFDW), redox potential (EhNHE, mV), total free sulphides (µM), and macrofauna statistics for Forsyth Bay (FOR), October 2018. ................................................................................................................................. 11

Figure 8. Average (± SE) total recoverable and dilute-acid-extractable zinc concentrations at the Forsyth Bay (FOR) farm site 2013-2018. .......................................................................... 14

Figure 9. Chlorophyll-a (chl-a), dissolved oxygen (DO), salinity, temperature and turbidity (optical back-scatter; OBS), as measured by a sensor array raised through the water column, at the Forsyth Bay (FOR) Pen 1 and PS-Ctl-3 stations, October 2018. ............. 15

Figure 10. Location of the farm across the three locations since 2001: Waihinau Bay (WAI) original position, WAI 50 m inshore position, and Forsyth Bay (i.e. fallowed). ................. 16

Figure 11. Annual feed inputs (December through November) at the Waihinau Bay (WAI) salmon farm, 2005–2018. .............................................................................................................. 17

Figure 12. Monthly feed inputs at the Waihinau Bay (WAI) salmon farm from December 2017 to November 2018................................................................................................................. 17

Figure 13. Soft-sediment sampling locations at the Waihinau Bay (WAI) salmon farm site. ............. 18 Figure 14. Representative images of the seafloor at each of the Waihinau Bay (WAI) salmon farm

monitoring stations, October 2018. ................................................................................... 20 Figure 15. Sediment organic matter (% ash-free dry weight; AFDW), redox potential (EhNHE, mV),

total free sulphides (µM), and macrofauna statistics for Waihinau Bay (WAI), October 2018. ................................................................................................................................. 23

Figure 16. Chlorophyll-a (chl-a), dissolved oxygen (DO), salinity, temperature and turbidity (optical back-scatter; OBS), as measured by a sensor array raised through the water column, at the Waihinau Bay (WAI) farm sites and the PS-Ctl-1 station, October 2018. . 27

Figure 17. Annual feed inputs (December through November) at the Otanerau Bay (OTA) salmon farm, 2005–2018. .............................................................................................................. 28

Figure 18. Monthly feed inputs at the Otanerau Bay (OTA) salmon farm from December 2017 to November 2018................................................................................................................. 29

Figure 19. Soft-sediment sampling locations at the Otanerau Bay (OTA) salmon farm site. ............ 30 Figure 20. Representative images of the seafloor at each of the Otanerau Bay (OTA) salmon

farm monitoring stations, October 2018. ........................................................................... 31 Figure 21. Sediment organic matter (% ash-free dry weight; AFDW), redox potential (EhNHE, mV),

total free sulphides (µM), and macrofauna statistics for Otanerau Bay (OTA), October 2018. ................................................................................................................................. 34

Figure 22. Chlorophyll-a (chl-a), salinity, temperature and turbidity (optical back-scatter; OBS), as measured by a sensor array raised through the water column, at the Otanerau Bay (OTA) farm sites and the QC-Ctl-2 station, October 2018. ............................................... 38

Figure 23. Annual feed inputs (December through November) at the Ruakaka Bay (RUA) salmon farm, 2005–2018. .............................................................................................................. 39


ix

Figure 24. Monthly feed inputs at the Ruakaka Bay (RUA) salmon farm from December 2017 to November 2018................................................................................................................. 40

Figure 25. Soft-sediment sampling locations at the Ruakaka Bay (RUA) salmon farm site. ‘QC-Ctl’ = Queen Charlotte Sound Control. ...................................................................... 41

Figure 26. Representative images of the seafloor at each of the Ruakaka Bay (RUA) salmon farm monitoring stations, October 2018. ................................................................................... 42

Figure 27. Sediment organic matter (% ash-free dry weight; AFDW), redox potential (EhNHE, mV), total free sulphides (µM), and macrofauna statistics for Ruakaka Bay (RUA), October 2018. ................................................................................................................................. 45

Figure 28. Chlorophyll-a (chl-a), salinity, temperature and turbidity (optical back-scatter; OBS), as measured by a sensor array raised through the water column, at the Ruakaka Bay (RUA) farm sites and the QC-Ctl-3 station, October 2018. .............................................. 49

LIST OF TABLES

Table 1. Environmental quality standards (EQS) for each ‘zone’, as summarised from the resource consents (excluding Waihinau Bay), along with the Enrichment Stage (ES) assumed for each zone. ...................................................................................................... 4

Table 2. ANZECC (2000) Interim Sediment Quality Guideline concentrations for copper and zinc (mg/kg). ........................................................................................................................ 4

Table 3. Average Enrichment Stage (ES) scores and 95% confidence intervals (95% CI) calculated for indicator variables, and overall, for each Forsyth Bay (FOR) farm sampling station in October 2018. .................................................................................... 10

Table 4. Comparison of average (± 95% CI) overall Enrichment Stage scores at the Forsyth Bay (FOR) farm monitoring stations over the current and previous four assessments. ... 12

Table 5. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Forsyth Bay (FOR) pen samples, October 2018. .................................................................................. 13

Table 6. Average Enrichment Stage (ES) values and 95% confidence intervals (95% CI) calculated for indicator variables, and overall, for each Waihinau Bay (WAI) station (October 2018). ................................................................................................................. 22

Table 7. Comparison of average overall Enrichment Stage scores at the Waihinau Bay (WAI) farm monitoring stations over the current and previous four assessments. ..................... 24

Table 8. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Waihinau Bay (WAI) pen samples, October 2018. ........................................................................... 25

Table 9. Average Enrichment Stage (ES) values and 95% confidence intervals (95% CI) calculated for indicator variables, and overall, for each Otanerau Bay (OTA) station (October 2018). ................................................................................................................. 33

Table 10. Comparison of average overall Enrichment Stage scores at the Otanerau Bay (OTA) farm monitoring stations over the current and previous four assessments. ..................... 35

Table 11. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Otanerau Bay (OTA) pen samples, October 2018. ........................................................................... 36

Table 12. Average Enrichment Stage (ES) values and 95% confidence intervals (95% CI) calculated for indicator variables, and overall, for each Ruakaka Bay (RUA) station (October 2018). ................................................................................................................. 44

Table 13. Comparison of average overall Enrichment Stage scores at the Ruakaka Bay (RUA) farm monitoring stations over the current and previous four assessments. ..................... 46

Table 14. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Ruakaka Bay (RUA) pen samples, October 2018. .......................................................................... 47

Table 15. Overview of New Zealand King Salmon ‘low-flow’ salmon farm compliance in the context of the assumed Enrichment Stage of the consent, and the best management practice guidelines (BMP; MPI 2015). .............................................................................. 54


LIST OF APPENDICES

Appendix 1. General methods for soft-sediment sampling. .................................................................. 56 Appendix 2. General methods for inshore habitat assessments. ......................................................... 58 Appendix 3. General methods for water column sampling. .................................................................. 58 Appendix 4. Full results for the Forsyth Bay (FOR) salmon farm. ........................................................ 59 Appendix 5. Historical comparison of metals. ....................................................................................... 63 Appendix 6. Full results for the Waihinau Bay (WAI) salmon farm. ...................................................... 64 Appendix 7. Full results for the Otanerau Bay (OTA) salmon farm. ..................................................... 68 Appendix 8. Full results for the Ruakaka Bay (RUA) salmon farm. ...................................................... 72


1

1. INTRODUCTION

The New Zealand King Salmon Co. Limited (NZ King Salmon) is the largest finfish

farming company in New Zealand and has been operating in the Marlborough Sounds

region for over 30 years. NZ King Salmon has consents for 11 farm sites in the region

(Figure 1). Presently, eight of these sites are stocked with fish and three sites are

fallowed or vacant.

Figure 1. Map of the Marlborough Sounds area indicating the location of the Forsyth Bay, Waihinau Bay, Otanerau Bay and Ruakaka Bay farm sites (red dots) and other NZ King Salmon consented farm sites (black dots).


2

NZ King Salmon is required to undertake environmental monitoring and reporting in

accordance with its marine farm consents1. The present monitoring programme is

conducted under a marine environmental monitoring adaptive management plan

(MEMAMP), prepared by Cawthron Institute (Cawthron) on behalf of NZ King Salmon,

and approved by Marlborough District Council (MDC) prior to implementation.

This report presents the results of monitoring undertaken in October 2018 at Forsyth

Bay (FOR), Waihinau Bay (WAI), Otanerau Bay (OTA) and Ruakaka Bay (RUA) ‘low-

flow’ farm sites2.

Monitoring undertaken at these low-flow farms in 2018 addressed:

• depositional effects on soft-sediment and inshore habitats

• effects on some aspects of water quality.

An overview of the sampling methodology is provided in Appendices 1-3, with specific

details for each site provided in the relevant section for each farm within the report.

Detailed methodology and rationale for the sampling approach at all four farms can be

found in the most recent MEMAMP (Newcombe & Elvines 2018); copies are held by

MDC and NZ King Salmon. The MEMAMP is updated and modified annually to

accommodate the most relevant and effective sampling methods. Further rationale

and details related to the general monitoring procedures can be found in the Best

Management Practice (BMP) guidelines developed for salmon farming in the

Marlborough Sounds region (MPI 2015).

1 Except for at the Waihinau Bay farm, whereby the existing consent conditions have no specific requirements

relating to seabed effects and environmental monitoring. 2 ‘Low-flow’ sites have a mean current speed of less than 10 cm/s (Keeley et al. 2013).


3

2. COMPLIANCE FRAMEWORK

2.1. Enrichment

The environmental monitoring results from soft-sediment habitats are used to

determine whether the farms are compliant with the environmental quality standards

(EQS) specified in the consent conditions for each farm (except the WAI site). The

EQS are based on a seabed impact ‘zones concept’, an approach that provides an

upper limit to the spatial extent and magnitude of seabed impacts (Keeley 2012).

The EQS specified in the consent conditions (Table 1) do not set precise parameters

for the allowable enrichment states within the zones. This is particularly true when

dealing with intermediate stages on the enrichment continuum. Consequently, it is

difficult to report definitively on compliance with some consent conditions. Best

Management Practice (BMP) guidelines for salmon farming in the Marlborough

Sounds region have been developed through a targeted working group process and

represent the industry operational goal for environmental effects (BMP; MPI 2015).

Although adherence to the BMP guidelines is not required formally under the

operating consent conditions, they do provide additional context against which to

compare enrichment levels (assessed using Enrichment Stages; ES) and copper and

zinc accumulation in the sediments (see Appendix 1). It is also worth noting that

compliance zones for the BMP guidelines3 differ from those in the current farm

consents, which have a three or four zone design.

In previous reporting, Cawthron has endeavoured to interpret the existing conditions

in a quantitative manner and has ‘assumed’ the equivalent Enrichment Stages

(assumed ES; Table 1) for each of the consented zones according to the description

provided by the consent wording. Although somewhat subjective, this approach was

guided by the language and the intent of the consent conditions as much as

practicable. When discussing the results, reference is also made to the ES thresholds

set out in the BMP guidelines, to provide further context.

3 The BMP approach comprises only two ‘zones’; the ‘zone of maximum effect’ and the transition zone, the outer

boundary of which is termed the ‘outer limit of effects’.


4

Table 1. Environmental quality standards (EQS) for each ‘zone’, as summarised from the resource consents (excluding Waihinau Bay), along with the Enrichment Stage (ES) assumed for each zone.

Spatial extent Description and bottom line Assumed ES**

Beneath the pens and out to 50 m from their outside edge

Sediments become highly impacted and contain low species diversity, dominated by opportunistic taxa (e.g. polychaetes, nematodes). It is expected that a gradient will exist within this zone, with higher impacts present directly beneath the pens.

Less than 6.0*

From 50 to 150 m from the outside edge of the pens

A transitional zone. Within this zone, some enrichment and enhancement of opportunistic species may occur, however species diversity remains high with no displacement of functional groups. It is expected that a gradient will also exist within this zone.

3.5 or less*

Beyond 150 m from the outside edge of the pens

Normal conditions (i.e. background or reference conditions).

2.5 or less And

No more than 0.5 greater than the highest ES score

for a relevant reference site*

These conditions are not permitted beneath any NZKS farm

Sediments that are anoxic and azoic (i.e. no life present).

7

* Refer to MPI (2015) for further details relating to the ES continuum.

** Not explicitly specified in the farm consents.

2.2. Copper and zinc

Under the current consents there are no requirements to monitor copper and zinc

levels in the sediment, nor are there EQS against which to compare compliance for

these metals. However, results can be put in the context of the BMP guidelines (MPI

2015), which state that the ANZECC (2000) ISQG-Low4 criteria for copper and zinc as

the most appropriate first tier trigger values for sediments beneath farms (Table 2).

Therefore, these guideline thresholds should be used to trigger further action if

exceeded. For more information regarding the copper and zinc monitoring approach,

readers are referred to the BMP (MPI 2015).

Table 2. ANZECC (2000) Interim Sediment Quality Guideline concentrations for copper and zinc

(mg/kg).

ISQG-Low ISQG-High

Copper 65 270

Zinc 200 410

4 The Interim Sediment Quality Guideline-Low (ISQG-Low) and -High (ISQG-High) criteria represent two distinct

threshold levels under which biological effects are predicted. The lower threshold (ISQG-Low) indicates a possible biological effect while the upper threshold (ISQG-High) indicates a probable biological effect.


5

3. FORSYTH BAY

3.1. Site details and history of feed usage

The FOR farm site was established in 1994. Water depth at the site is c. 32 m, and

the net pens extend from the surface to a depth of c. 20 m. The average water current

speed is c. 3 cm/s. The FOR site has been managed on a rotational/fallowing basis

with the WAI site (Figure 2). FOR has been fallowed four times since its

establishment; most recently from mid-January 2016 to the present. Over the past

decade, feed inputs at this farm have ranged from 0 to 3,261 tonnes per annum

(December through November; Figure 3).

At the time of monitoring there were farm structures present at the FOR site, however,

these pens were not stocked and no feed had been discharged at the site since the

farm was fallowed. Despite the site have no ongoing feed inputs, it was recommended

that benthic monitoring was continued to track seabed recovery, given the highly

impacted conditions observed in previous monitoring (Fletcher et al. 2018).

Figure 2. Operational state of the Forsyth Bay (FOR) farm (occupied vs. fallowed) from 1994–2017.

Figure 3. Annual feed inputs (December through November) at the Forsyth Bay (FOR) salmon

farm, 2005-2017. Feed input data provided by NZ King Salmon.


6

3.2. Sampling overview

Annual monitoring at FOR was undertaken on 24 October 2018, using the techniques

summarised in Appendices 1-3.

Sampling stations are shown in Figure 4. Pen 2 and the four single-replicate stations

(Pen a-d) are all located within the old pen edge boundary (i.e. directly beneath the

pen position) to track the recovery of sediments in the worst affected areas. The

Pen 1 station was not sampled as part of the current monitoring, due to the relatively

minor effects being recorded here in the previous assessment. The 50 m and 150 m

stations at this farm were also not sampled as the farm is currently fallowed. Drop

camera video assessments were made only at the Pen 2 station (not at Pen a-d since

these are in close proximity to Pen 2). A suitable sediment core could not be collected

from the Pen c replicate due to considerably high amounts of shell hash. As such,

organic matter and metal analyses were not carried out for this sample.

Video footage for inshore habitat assessments was collected along two transects

using a towed drop-camera set-up with a surface image feed. Transects ran from the

shore toward the net pens and followed those surveyed in 2014 and 2016 (see

Figure 4). Water column monitoring was carried out at the Pen 1 and PS-Ctl-3

stations. There were no other variations to the typical sampling procedure as set out

in the MEMAMP (Newcombe & Elvines 2018).

Figure 4. Soft-sediment sampling locations at the Forsyth Bay (FOR) site. The Pen 1 station was

not sampled in Oct 2018. ‘PS-Ctl’ = Pelorus Sound Control. Position accuracy is ± 5 m.


7

3.3. Soft-sediment habitat description

The seabed at Pen 2 comprised soft muddy brown-grey sediments (see Figure 5). No

Beggiatoa-like bacterial coverage, outgassing or conspicuous epifauna were observed

in the video footage.

The substrate at the reference stations also had predominantly soft muddy sediments.

Bioturbation, in the form of burrow holes (some with polychaete tentacles visible) and

trail marks, was evident at both the near-field (PS-Ctl-2) and far-field (PS-Ctl-3)

reference stations. In contrast to the previous monitoring, conspicuous epifauna were

largely absent apart from a single hydroid noted at PS-Ctl-3.

Figure 5. Representative images of the seafloor at each of the Forsyth Bay (FOR) salmon farm

monitoring stations, October 2018.


8

3.4. Assessment of seabed enrichment

The range of overall ES scores across the Pen stations was ES 3.2–4.4 (Table 3),

and all stations would be deemed compliant in the context of both the assumed ES

and the BMP guidelines (see Table 1). The overall ES score for the Pen 2 station

(ES 3.2 ± 0.3) represents a noticeable reduction from the two most recent monitoring

assessments (May 2017: ES 5.9 ± 0.7 and October 2017: ES 5.2 ± 0.3; Table 4).

Although the seabed at the Pen 2 station demonstrates some level of recovery,

seabed condition indicators still showed a degree of impact. When compared to

reference conditions, Pen 2 had very highly elevated organic matter (16.8–9.1%),

reduced redox potential, and moderately elevated sulphides (1084–1366 µM)

(Figure 7). This was consistent with observations of impacted conditions deeper in the

sediment profile (> 1–3 cm), as seen at the time of sampling in the grab sample and

core samples (see Figure 6). However, despite the clearly impacted organic content

and sediment chemistry indicators, macrofaunal abundances were only slightly

elevated and taxa richness has increased noticeably since the previous assessments

(see Figure A4.1). Community structure still shows some differences compared to

reference conditions (e.g. the invasive bivalve Theora lubrica and dorvilleid worms

remain the predominant taxa).

ES scores at the surrounding single replicate sampling stations were considerably

reduced from the previous monitoring assessment (October 2018: ES 3.2-4.4

compared with October 2017: ES 4.7-6.4; n = 1 per station). Organic matter was still

very high for two stations (Pen a: 19.1% AFDW and Pen b: 20% AFDW; Figure 7).

Three of the stations also showed reduced redox potential, and moderately elevated

sulphides (Pen a-c: 1,004–1,265 µM) when compared to reference conditions

(Figure 7). Total abundances were high at one station (1,326 individuals per core;

Pen d), with this sample dominated by capitellid worms (1,288 individuals). The

remaining three stations had slightly to moderately elevated total abundances

(100-446 individuals per core). Taxa richness has increased over the previous 12

months (10–24 taxa per core), suggesting recolonisation of the sediments by non-

opportunistic taxa has begun. Overall, macrofaunal communities appear to have

recovered somewhat since the previous survey.

Organic matter remains high in most areas, with no change shown from the last two

monitoring assessments. This may in part be due to the limited assimilative capacity

of the still-recovering macrofaunal communities, and/or the persistence of farm-

derived organic matter deeper in the sediment profile. We note that enrichment levels

beneath the farm are low enough that would allow restocking of the area under both

the consent and the BMP guidelines. We do not consider this advisable for the

following reasons:


9

• The persistence of poor sediment conditions deeper in the sediment profile

—it is unlikely that the farm could sustain past input levels, or even reduced input

levels, without quickly becoming non-compliant with the EQS for enrichment.

• Some indicators have not recovered—monitoring should continue at the

impacted area to document recovery.

• Seabed remedial work may be required—due to the depth of the impacted

sediments and the low energy nature of the site, it is possible that the seabed will

not fully recover unless remedial work is undertaken.

A full breakdown of indicator variable contributions is provided in Appendix 4.

However, if restocking of this site occurs in the near-term, pens should be placed so

that deposition of organic matter is minimal in the middle of the lease area (where

sediments are presently most impacted).

Figure 6. Representative sediment grab and core photos of the pen and control station sampling

sites at the Forsyth Bay (FOR) farm, October 2018.


10

Table 3. Average Enrichment Stage (ES) scores and 95% confidence intervals (95% CI) calculated for indicator variables, and overall, for each Forsyth Bay (FOR) farm sampling station in October 2018. Pen a-d were single replicate samples. A full breakdown of indicator variable contributions is provided in Appendix 4. Both the assumed ES and the allowable ES under the BMP guidelines (MPI 2015) are shown for context.

Station Summary of indicator variables ES

(95% CI)

Pen 2 Organic matter (%OM) very high (4 x reference station average), redox variable (negative in two replicates), sulphides highly elevated. Total abundance slightly elevated (128-218 individuals per core) but taxa richness normal (16-22 taxa per core).

Organic loading: 5.9 (0.2)

Sediment chemistry: 4.0 (0.3)

Macrofauna: 2.6 (0.2)

Overall: 3.2 (0.3)

Pen a %OM very high (4 x reference station average), redox slightly negative, sulphides highly elevated. Total abundance slightly elevated (100 individuals in the core) and taxa richness low compared to reference stations (14 taxa).

Organic loading: 6.1

Sediment chemistry: 4.2

Macrofauna: 3.0

Overall: 3.5

Pen b %OM very high (4 x reference station average), redox slightly negative, sulphides highly elevated. Total abundance slightly elevated (175 individuals in the core) and taxa richness low compared to reference stations (13 taxa).



Macrofauna: 3.1

Overall: 3.6

Pen c No data available for %OM. Redox moderately negative, sulphides highly elevated. Total abundance elevated (446 individuals in the core) but taxa richness comparable to reference stations (24 taxa).

Organic loading: -


Macrofauna: 2.9

Overall: 3.2

Pen d %OM slightly elevated, redox positive but lower than reference, sulphides elevated. Total abundance high (1,326 individuals in the core) and taxa richness low compared to reference stations (10 taxa).



Macrofauna: 4.9

Overall: 4.4

Assumed ES < 6.0

BMP ES ≤ 5.0

PS-Ctl-2 Normal reference conditions. Macrofauna community composition indicative of background seabed conditions.




Overall: 1.9 (0.0)

PS-Ctl-3 Normal reference conditions. Macrofauna community composition indicative of background seabed conditions.




Overall: 2.1 (0.2)


11

Figure 7. Sediment organic matter (% ash-free dry weight; AFDW), redox potential (EhNHE, mV),

total free sulphides (µM), and macrofauna statistics for Forsyth Bay (FOR), October 2018. Error bars ± 1 SE, n = 3 samples unless otherwise indicated. No macrofauna data were collected for the 50 m and 150 m stations. Organic matter was not able to be calculated for one single replicate station (Pen c).


12

Table 4. Comparison of average (± 95% CI) overall Enrichment Stage scores at the Forsyth Bay (FOR) farm monitoring stations over the current and previous four assessments. The FOR site has been fallowed since mid-January 2016 until present.

Overall Enrichment Stage score

2015 2016 2017

(May)

2017

(Oct) 2018

Pen 1 5.8 (0.4) 4.8 (1.7) 5.2 (0.7) 3.0 (0.1) -

Pen 2 6.0 (0.3) 6.5 (0.1) 5.9 (0.7) 5.2 (0.2) 3.2 (0.2)

Pen 3 5.1 (0.1) 5.4 (0.5) 3.4 (0.2) - -

Pen a - - 6.7 6.0 3.5

Pen b - - 6.7 4.7 3.6

Pen c - - 5.7 5.1 3.2

Pen d - - 4.8 6.4 4.4

50 m (Zone 1–2 boundary) 2.5 (0.4) 2.6 (0.1) - 2.7 (0.3)* -

150 m (Zone 2–3 boundary) 2.0 (0.1) 2.2 (0.1) - 2.0 (0.0)* -

PS-Ctl-2 1.8 (0.1) 2.0 (0.1) - 2.1 (0.1) 1.9 (0.0)

PS-Ctl-3 2.0 (0.1) 2.0 (0.2) - 2.0 (0.0) 2.1 (0.2)

* Assessed on organic loading and sediment chemistry only

3.5. Copper and zinc concentrations

Total recoverable copper concentrations from four of the six replicates from beneath

the pens exceeded the ISQG-Low (> 65 mg/kg) criterion (Table 5). Of these samples,

one replicate also exceeded the ISQG-High criterion (> 270 mg/kg; Pen 2c). The

overall pen average of copper in the dilute-acid-extractable fraction (an indicator of

bio-availability; ANZECC 2000) was 19.1 ± 3.8 mg/kg (n = 6), and no replicates

exceeded the ISQG-Low threshold. As such, it appears that a reasonably large

proportion of copper beneath the net pens is bound in particulate form, and no

ecological effects are expected as a result. Total recoverable copper levels have

historically been variable at the FOR site, with the results of this year’s monitoring

representing a slight decrease from the last assessment, which had the highest

readings since 2008 (see Appendix 5).

Both total recoverable and dilute-acid-extractable zinc concentrations exceeded the

ISQG-High criterion for all six replicates (> 410 mg/kg; Table 5). It should be noted

that the dilute-acid-extractable concentration was higher than the total recoverable

fraction in three of the six samples (Pen 2a, Pen 2b and Pen a). As with last year’s

monitoring, it appears that total recoverable zinc in these samples was

underestimated due to as yet undetermined sample matrix-specific chemical

interactions with the acid digestion conditions. The results from the weak acid

extractable analysis are considered to be more dependable for these replicates.

Overall, zinc results indicate that a very high level of potentially bio-available zinc


13

persists in sediments beneath the FOR pen site, and ecological effects are probable

as a result.

There has been a noticeable increase in the overall pen average for both the total

recoverable and dilute-acid-extractable fractions (see Figure 8), with levels of both

almost double that of the previous monitoring round (total recoverable zinc: 773 ± 138

mg/kg; dilute-acid-extractable zinc: 598 ± 94 mg/kg, n = 10; see Fletcher et al. 2018).

Similar to copper, total recoverable zinc levels have historically been variable at the

FOR site, with the levels recorded in this year’s monitoring the second highest over

the previous 14 years (see Appendix 5). It should also be noted that the

concentrations recorded in the dilute-acid-extractable fraction are the highest

recorded at any farm site monitored. Although highly variable between replicate

samples, the persistent and increasing levels of potentially bio-available zinc in the

sediments, despite the farm being fallowed since January 2016, is of significant

concern.

Additional testing is recommended to understand the mechanism of the persistent and

increasing zinc levels at this site. The design of the testing should also consider the

limitations of the analytical methodology for testing total recoverable zinc in these

sediments, as well as the effects of zinc on seabed communities.

Table 5. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Forsyth Bay

(FOR) pen samples, October 2018. The Pen 2 and overall averages (± SE) are also shown. The ISQG threshold values are for both recoverable and extractable forms of each metal. Bold values exceed ANZECC (2000) ISQG-Low, and underlined values exceed ISQG-High.

Copper Zinc

Sample Total

recoverable Dilute-acid-extractable

Total recoverable

Dilute-acid-extractable

Pen 2

a 152.0 22.0 490.0 600.0*

b 64.0 17.3 2600.0 2800.0*

c 510.0 17.4 1630.0 1540.0

Pen 2 average 242.0 (± 136.4) 18.9 (± 1.6) 1573.3 (± 609.8) 1646.7 (± 637.3)

Pen a a 116.0 35.0 600.0 650.0*

Pen b a 72.0 16.8 2400.0 850.0

Pen c a - - - -

Pen d a 16.1 6.2 560.0 240.0

Overall Pen average 155.0 (± 73.5) 19.1 (± 3.8) 1326.7 (± 419.3) 1166.7 (± 358.9)

ANZECC ISQG-Low 65 200

ANZECC ISQG-High 270 410

* The dilute acid extractable fraction being higher than the total recoverable fraction was noted as an anomaly by

Hill Laboratories. This has been observed in previous monitoring years and is believed to be due to the form of zinc present in the samples being more soluble in dilute acid solutions. The dilute-acid-extractable fraction should be used as the bottom line.


14

Figure 8. Average (± SE) total recoverable and dilute-acid-extractable zinc concentrations at the

Forsyth Bay (FOR) farm site 2013-2018. Note that an extreme outlier (a suspected large paint particulate) in 2014 was excluded from this plot for clarity. Analysis was performed on bulk sediments in all years except 2015 (finer sediment fractions [< 250 μm] only). Only total recoverable zinc was assessed in 2013.

3.6. Inshore habitats

Both video transects began in the shallow subtidal zone inshore of the farm structures

(see Figure 4). The substrate along Transect 1 was dominated by loose cobble with

extensive coverage of crustose coralline algae. Bubble weed (Colpomenia sp.)

clumps were intermittent throughout the transect. Patches of sandy substrate became

more common with increasing water depth. Toward the end of Transect 1 the

substrate shifted to soft mud with considerable amounts of shell hash and patches of

intact, empty shells. Sediment deposition increased with distance from the shoreline,

along with the occurrence of trail marks and isolated clumps of drift algae (including

Ulva spp. and sea rimu, Caulerpa sp.). Epifauna observed included eleven-armed sea

stars (Coscinasterias calamaria), kina (Evechinus chloroticus), and large solitary sea

squirts (Cnemidocarpa sp.).

The substrate along Transect 2 was initially comparable to Transect 1. However, as

depth increased, dense patches of intact, empty shell material become more

prevalent. Conspicuous epifauna were largely absent from Transect 2 aside from sea

cucumbers (Australostichopus mollis) and eleven-armed sea stars. Overall, no signs

of excessive deposition, nutrient enrichment or other obvious changes in visual

characteristics of the inshore habitats were observed on either transect.


15

3.7. Water column

Only the pen station and one control site were sampled at FOR in 2018. All

parameters displayed similar water column characteristics at the two sites (Figure 9).

Mild stratification was apparent in the temperature, and to a lesser extent, salinity

profiles. At the pen station, chlorophyll-a (chl-a) concentration (a proxy for

phytoplankton biomass) was lower at the surface and higher mid-water. Chl-a

concentrations were all less than 2.5 µg/L. There was no indication of lower dissolved

oxygen near the seabed at the pen station than at the control station. Accordingly, no

farm-related effects on the water column were apparent.

Figure 9. Chlorophyll-a (chl-a), dissolved oxygen (DO), salinity, temperature and turbidity (optical

back-scatter; OBS), as measured by a sensor array raised through the water column, at the Forsyth Bay (FOR) Pen 1 and PS-Ctl-3 stations, October 2018. PS-Ctl = Pelorus Sound Control.


16

4. WAIHINAU BAY

Consent conditions for the WAI farm (MFL 456) have no specific monitoring

requirements relating to seabed effects, or other environmental effects. As such, the

monitoring presented in this report is voluntarily conducted by NZ King Salmon and

does not determine site compliance. The EQS from the BMP guidelines (MPI 2015)

are used to provide context against which to compare enrichment, and copper and

zinc levels.


The WAI salmon farm has been in operation since 1989. Water depth at the farm site

is c. 26 m, with the net pens extending from the surface to a depth of c. 20 m. Flows

at the site are low-to-moderate; mid-water flows average 8.4 cm/s, with maximum

velocities up to 33.7 cm/s.

The WAI farm has been managed on a rotational/fallowing basis with the FOR site. In

addition, the WAI farm position varies within the consented area, but is usually

situated over 1 of 2 approximate locations: the original farm position (i.e. 2015/2016),

and 50 m inshore of the original position. A timeline of farm movements over the past

18 years is illustrated in Figure 10. WAI was fallowed for 4 months in early 2018

(January 2018 through to late April 2018) before it was restocked with smolt.

Since 2005, feed inputs at the farm have ranged from 0 to 3,786 tonnes per annum

(Figure 11). Approximately 1,830 tonnes of feed was discharged in the 12-month

period prior to the 2018 survey (November 2017 through October 2018; note this time

period differs to that in Figure 11 and Figure 12 which show a period that allows

historical comparisons). Approximately 1,429 tonnes of feed were discharged in the

six months immediately prior to monitoring (i.e. after restocking).

Figure 10. Location of the farm across the three locations since 2001: Waihinau Bay (WAI) original

position, WAI 50 m inshore position, and Forsyth Bay (i.e. fallowed).


17

Figure 11. Annual feed inputs (December through November) at the Waihinau Bay (WAI) salmon farm, 2005–2018. Feed input data provided by NZ King Salmon.

Figure 12. Monthly feed inputs at the Waihinau Bay (WAI) salmon farm from December 2017 to

November 2018. Feed input data provided by NZ King Salmon.


18


Sampling for the WAI annual monitoring was undertaken on 24 October 2018, using

the techniques summarised in Appendices 1-3.

Sampling stations are shown in Figure 13. The farm structures had been moved

inshore from the previous annual monitoring. In addition, only the northern half of the

farm structures were stocked with fish at the time of sampling. As such, the location of

the pen stations was moved to better reflect expected sediment effects.




Figure 13). Water column monitoring was carried out at all farm stations as well as the

PS-Ctl-1 station. There were no other variations to the typical sampling procedure as

set out in the MEMAMP (Newcombe & Elvines 2018).

Figure 13. Soft-sediment sampling locations at the Waihinau Bay (WAI) salmon farm site. ‘PS-Ctl’ = Pelorus Sound Control. Position accuracy is ± 5 m.


19


The seabed at the pen stations comprised brown to grey muddy sediments (see

Figure 14), with trace levels of Beggiatoa-like bacteria visible throughout video

footage of the site. No outgassing from the sediment was observed. Polychaete

worms (likely Dorvilleidae or Capitella sp.) were abundant and seen moving on the

surface of the substrate, often forming ‘clusters’ or ‘balls’, and were frequently

associated with fish faecal material. Several egg casings and unattached green

foliose algae were visible at the Pen 1 station. The only noticeable epifauna observed

was a solitary hydroid at the Pen 2 station.

The substrate at the 180 m station comprised soft muddy sediments, lighter in colour

than sediments at the pen stations. Burrow holes (some with polychaete tentacles

visible) and trail marks were also evident. A solitary opalfish (Hemerocoetes

monopterygius) was sighted. Video footage at the reference stations was similar to

the 180 m station, with predominantly light-grey, soft muddy sediments. An eleven-

armed sea star (Coscinasterias muricata) was observed at the near-field station

(PS-Ctl-1). Burrow holes and trail marks were observed at both reference stations.


20

Figure 14. Representative images of the seafloor at each of the Waihinau Bay (WAI) salmon farm



21


The overall ES scores at the Pen 1 (ES 5.2 ± 0.7) and Pen 2 (ES 5.0 ± 0.2) stations

are indicative of very highly enriched sediments (Table 6). Both pen stations had high

organic matter and very poor sediment chemistry. One replicate sample from Pen 1

had particularly high organic matter (22% AFDW; Figure 15). Redox potential was

strongly negative for all the pen station samples. Sulphide measurements were also

elevated across all replicate samples, with one sample from Pen 2 extremely high

(16,055 µM; Figure 15). Enrichment at the Pen 1 station has increased since the

previous monitoring round, while enrichment levels at the Pen 2 station have

decreased (ES 4.8 ± 0.1 and ES 5.4 ± 0.3, respectively).

Macrofaunal communities at both stations were consistent with ‘peak-of-opportunist’

conditions5 (i.e. very low taxa richness and highly elevated abundances).

Communities were dominated by capitellid worms, nematodes, and to a lesser extent,

dorvilleid polychaetes. The Pen 1 sample with particularly high organic matter was

anomalous, in that it had considerably reduced macrofaunal abundances compared to

the other samples from this station. Combined with the poor sediment chemistry, it is

possible there has been a regression to ‘post-peak’ conditions in localised areas at

the Pen 1 station. As would be expected, sediment enrichment adjacent to the net

pens has noticeably increased since the WAI site become operational again after an

extended fallowing period during 2016 (see Table 7).

Under the BMP guidelines, the Pen 2 station would be within the allowable ES

(ES ≤ 5.0) for the zone of maximal effect (ZME). At the Pen 1 station, the ES score

(ES 5.2 ± 0.7) would elicit an ‘alert’ management response (i.e. as the lower bound of

the 95% confidence interval is < 5.0; see MPI 2015). However, we acknowledge that

environmental monitoring at this site is undertaken voluntarily, so this would be done

at the discretion of the consent holder. Despite there being no environmental

monitoring conditions in the current consent, it is advisable that feed input at the WAI

site is closely monitored to prevent further deterioration.

Organic matter, sediment chemistry and macrofaunal community indicators at the

180 m station were comparable to reference sites. The overall ES score of ES 2.2

(± 0.1) was reasonably similar to both the near- and far-field reference stations (ES

2.0 ± 0.2 and ES 2.1 ± 0.2, respectively). Under the BMP guidelines, the 180 m

station would be within the allowable ES for the outer limit of effects (OLE; ES < 3.0).

A full breakdown of indicator variable contributions is provided in Appendix 6.

5 Refers to peak abundance of opportunistic taxa (e.g. capitellids and nematodes), where waste assimilation is

theoretically maximal (see Keeley et al. 2012, 2013).


22

Table 6. Average Enrichment Stage (ES) values and 95% confidence intervals (95% CI) calculated for indicator variables, and overall, for each Waihinau Bay (WAI) station (October 2018). See Appendix 6 for a full breakdown of indicator variable contributions. The allowable ES from the BMP guidelines (MPI 2015) is shown for context.

Summary of indicator variables

ES

(95% CI)

Pen 1 Organic matter (%OM) elevated in all samples, redox values highly negative, sulphides highly elevated. Total abundances very high in two samples (2,889 and 6,972 individuals per core) and number of taxa (6-12 per core) reduced. Very high abundances of capitellid worms.




Overall: 5.2 (0.7)

Pen 2 %OM elevated in all samples, redox values highly negative, and sulphides very highly elevated. Total abundances very high (1,981-3,514 individuals per core) and number of taxa very reduced (7-9 per core). Very high abundances of capitellid worms.




Overall: 5.0 (0.2)

BMP ES ≤ 5.0

180 m Normal %OM, redox values slightly reduced in two samples. Sulphides slightly elevated. Total abundances (69-181 individuals per core) and number of taxa (20-29 per core) similar to reference conditions.




Overall: 2.2 (0.1)

BMP ES < 3.0

PS-Ctl-1 Normal background conditions. Macrofauna community measures and composition indicative of background seabed conditions (90-117 individuals per core; 21-30 taxa per core).




Overall: 2.0 (0.2)

PS-Ctl-3 Normal background conditions. Macrofauna community measures and composition indicative of background seabed conditions (49-93 individuals per core; 17-24 taxa per core).




Overall: 2.1 (0.2)


23

Figure 15. Sediment organic matter (% ash-free dry weight; AFDW), redox potential (EhNHE, mV), total free sulphides (µM), and macrofauna statistics for Waihinau Bay (WAI), October 2018. Error bars ± 1 SE, n = 3 samples.


24

Table 7. Comparison of average overall Enrichment Stage scores at the Waihinau Bay (WAI) farm monitoring stations over the current and previous four assessments. Error bars represent ± 95% CI except in 2014 (± 1 SE).


2014 2015 2016 2017 2018

Pen 1 5.4 (0.2) * 4.6 (0.2) 2.8 (0.3) 4.8 (0.1) 5.2 (0.7)*

Pen 2 4.8 (0.1) * 3.1 (0.1) 3.4 (0.6) 5.4 (0.3) 5.0 (0.2)*

180 m (Zone 2–3 boundary) 2.1 (0.1) 2.1 (0.1) 2.3 (0.1) 2.2 (0.0) 2.2 (0.1)

PS-Ctl-1 2.1 (0.0) 2.0 (0.0) 1.7 (0.1) 2.1 (0.1) 2.0 (0.2)

PS-Ctl-3 1.8 (0.0) 2.1 (0.0) 2.0 (0.2) 2.0 (0.0) 2.1 (0.2)

* Sampled under the inshore pen position


A high level of variability in total recoverable copper concentrations between

replicates was noted for both the Pen 1 and Pen 2 stations (see Table 8). The Pen 1

average slightly exceeded the ISQG-Low criterion (65 mg/kg) for total recoverable

copper concentrations, while the Pen 2 average was below this threshold. Aside from

the previous year’s monitoring, there has been a general trend of decreasing total

recoverable copper levels at the WAI site since 2012 (see Appendix 5). Copper

concentration in the dilute-acid-extractable fraction (an indicator of bio-availability;

ANZECC 2000) were more consistent across replicates. No replicates from either of

the Pen stations exceeded the ISQG-Low threshold, with an overall pen average of

9.1 ± 1.3 mg/kg (n = 6). As such, no ecological effects of copper within the sediments

are expected.

Total recoverable zinc concentrations in four of the six pen samples exceeded the

ISQG-Low criterion (200 mg/kg; Table 8), with one replicate at the threshold for the

ISQG-High criterion (410 mg/kg; Pen 2c). Zinc concentrations for the dilute-acid-

extractable fraction also exceeded ISQG-Low for the same four replicate samples.

The overall pen average slightly exceeded the ISQG-Low criterion (202.7 ± 21.6

mg/kg). These results indicate that there is a relatively high level of potentially

bio-available zinc present in sediments beneath the WAI pen site, and localised

ecological effects are possible as a result.

Both the total recoverable and dilute-acid-extractable zinc concentrations recorded

represent a marked decrease from last year’s monitoring (see Fletcher et al. 2018).

As with copper, prior to last year’s monitoring a general trend of decreasing total

recoverable zinc levels at the WAI site had been observed since 2012 (see Appendix

5).


25

Table 8. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Waihinau Bay (WAI) pen samples, October 2018. Pen and overall averages (± SE) are also shown. The ISQG threshold values are for both recoverable and extractable forms of each metal. Bold values exceed ANZECC (2000) ISQG-Low.

Sample Total

recoverable copper


copper

Total recoverable

zinc


zinc

Pen 1

a 103.0 6.4 185.0 149.0

b 116.0 7.1 270.0 230.0

c 24.0 11.0 290.0 210.0

Pen 1 average 81.0 (± 28.8) 8.2 (± 1.4) 248.3 (± 32.2) 196.3 (± 24.4)

Pen 2

a 14.1 7.7 166.0 137.0

b 17.3 7.4 260.0 210.0

c 114.0 14.7 410.0 280.0

Pen 2 average 48.5 (± 32.8) 9.9 (± 2.4) 278.7 (± 71.1) 209.0 (± 41.3)

Overall pen average 64.7 (± 20.8) 9.1 (± 1.3) 263.5 (± 35.5) 202.7 (± 21.6)




Both transects began in the shallow subtidal zone inshore of the farm structures (see

Figure 13). Shallow water substrates along Transect 1 were predominantly a mix of

course sand, cobble and boulder. As depth increased, the substrate changed to shell

hash and then transitioned to sand. Increasing levels of sediment deposition were

noted closer to the farm structures and away from the shoreline. Epifauna observed

included brittle stars (Ophiopsammus maculata), sea cucumbers (Australostichopus

mollis), eleven-armed sea stars (Coscinasterias calamaria), kina (Evechinus

chloroticus) and colonial ascidians or sponges. Large barrel-shaped sponges were

also occasionally observed along this transect. Spotties (Notolabrus celidotus) and

blue cod (Parapercis colias) were also common.

Filamentous green algae (probably Cladophora sp.) was abundant in the shallows of

Transect 2, forming dense mats which covered the majority of the seabed. Larger

brown algae (Undaria pinnatifida) were also present. Footage of this area was unable

to be obtained in 2016 due to net pen construction (and nets and ropes were being

stored on the seabed in this area), but the survey in 2014 reported similar algal

growth. It should be noted that the presence of dense filamentous algal mats has

been documented in the wider Pelorus Sound region in recent years (see Pochon et

al. 2015). In addition, comprehensive snorkel surveys throughout the wider Pelorus

Sound region in September 2018 revealed the same phenomenon in a number of


26

bays in the absence of salmon farms (pers. obs. Lauren Fletcher). While high levels of

filamentous algae can indicate enrichment (Nelson 2013), the conditions observed

during the current assessment cannot reliably be attributed to farm-related activities.

The deeper portions of Transect 2 were predominately cobble with patchy green algal

cover interspersed with coarse sand, shell hash and intact shell material. Few

conspicuous epifauna were visible on Transect 2, with only one hermit crab seen. It is

recommended that future assessments of inshore habitats at the WAI site are carried

out along the same path as Transect 2 to detect any ongoing macro-algal bloom

conditions.

4.7. Water column

Water column monitoring at only one pen station was planned in the MEMAMP (note

that all monitoring at the WAI stations is voluntary); however, two are reported here

(Figure 16) as additional data were collected. Temperatures in surface waters were

greater than in deeper waters at all stations, and stratification was apparent at 2–3 m

in the salinity profiles. Low salinity waters were associated with higher turbidity (optical

back-scatter; OBS) at the 180 m and control (PS-Ctl-1) stations. A small peak in

turbidity was apparent near the seabed at all stations and did not seem to be

associated with proximity to the pens. Slightly higher turbidity was apparent

throughout the water column at Pen 1.

Chlorophyll-a (chl-a) concentrations (a proxy for phytoplankton biomass) generally

peaked mid-water and did not exceed 3 µg/L at any station.

Dissolved oxygen (DO) was somewhat lower in mid-waters at the pen stations, and

lower overall at Pen 1. This may indicate an effect of fish respiration. However, DO

was variable and did not decrease below 7.0 mg/L at any station. There was no

evidence of a more marked decrease in DO near the seabed at the pen stations than

at the other stations.


27

Figure 16. Chlorophyll-a (chl-a), dissolved oxygen (DO), salinity, temperature and turbidity (optical

back-scatter; OBS), as measured by a sensor array raised through the water column, at the Waihinau Bay (WAI) farm sites and the PS-Ctl-1 station, October 2018. Ps-Ctl = Pelorus Sound Control.


28

5. OTANERAU BAY


The OTA farm site was established in 1990. Water depth at the site is c. 36 m, and

the net pens extend from the surface to a depth of c. 20 m. Flows at the site are low-

to-moderate with average water current speeds of c. 6 cm/s.

Since 2005, feed inputs at this farm have ranged from 1,000 to 2,289 tonnes per

annum (Figure 17). There was an increase (~190 tonnes) in feed discharged for 2018,

with a total of 1,376 tonnes discharged over the 12 month period prior to monitoring

(note the time period differs from that in Figure 17 and Figure 18 which show a period

that allows historical comparisons). The site was fallowed and had no feed discharged

during January through March 2018 (Figure 18).

Figure 17. Annual feed inputs (December through November) at the Otanerau Bay (OTA) salmon farm, 2005–2018. Feed input data provided by NZ King Salmon.


29

Figure 18. Monthly feed inputs at the Otanerau Bay (OTA) salmon farm from December 2017 to



Sampling for the OTA annual monitoring was undertaken on 26 and 27 October 2018,

using the techniques summarised in Appendices 1-3.

Sampling stations are shown in Figure 19. The location of the farm structures had not

changed since the previous annual monitoring. The Pen 3 station at OTA

demonstrated the least effect of farming activities on biological communities in the

2017 sampling round. Monitoring is only required at two pen stations at low-flow

salmon farm sites (MPI 2015), so Pen 3 was not sampled in 2018.




Figure 19). Water column monitoring was carried out at all farm stations as well as

QC-Ctl-2 station. There are no other variations to the typical sampling procedure as

set out in the MEMAMP (Newcombe & Elvines 2018).


30

Figure 19. Soft-sediment sampling locations at the Otanerau Bay (OTA) salmon farm site. ‘QC-Ctl’ = Queen Charlotte Sound Control. Position accuracy is ± 5 m.


Video footage of the seabed from both pen stations revealed soft, dark muddy

sediments with shell and biofouling debris on the seafloor (see Figure 20). Both pen

stations featured Beggiatoa-like bacteria cover on shell edges and on the sediment

surface, as well as outgassing. The only noticeable epifauna was a hydroid at the

Pen 1 station.

Sediments at the 50 m and 150 m stations comprised soft, light brown-to-grey mud

and were more homogenous than at the pen stations. A single spiny dogfish (Squalus

acanthias) was observed at the 50 m station. At the 150 m station polychaete worms

were abundant, as were burrow holes and trail marks.

The substrate at the reference QC-Ctl-1 station was soft and muddy, similar to the

50 m and 150 m stations. A number of polychaete worms were visible on the surface

of the sediment, as were signs of bioturbation (burrow holes and trail marks). The

substrate at reference station QC-Ctl-2 had considerable shell hash and larger shell

debris present. A single blue cod (Parapercis colias) and a school of spotties

(Notolabrus celidotus) was observed at this station.


31

Figure 20. Representative images of the seafloor at each of the Otanerau Bay (OTA) salmon farm



32


Mean overall ES scores at the Pen stations were ES 5.0–5.5 (Table 9), indicating very

high enrichment beneath the pens. As with the previous monitoring round, Pen 1 had

the highest overall ES score (ES 5.5 ± 0.4), indicative of ‘post-peak’ conditions6.

Organic matter was elevated in two replicate samples, while redox potential was

reduced but variable across all replicates (Figure 21). All of the Pen 1 samples had

low macrofaunal taxa richness (3–8 taxa per core) and total abundances (161–752

individuals per core). Pen 1a sample characteristics were anomalous to the other

samples, with higher organic matter (12.1% AFDW), an extremely high sulphide

concentration (17,066 µM), and very low numbers of macrofauna present (161

individuals, representing 3 taxa). The macrofauna present was almost exclusively

capitellid and nematode worms. The ES score for the Pen 1 station is within the

assumed ES under the consent conditions. Under the BMP guidelines, the two

archive samples from this station would need to be processed before a compliance

outcome could be determined.

The overall ES score at the Pen 2 station was lower (ES 5.0 ± 0.5), and within the

allowable ES score in the context of both the assumed ES under the consent

conditions and the BMP guidelines. Organic matter and total free sulphides were

moderately elevated, and redox potential reduced, across all three samples

(Figure 21). Macrofaunal communities were consistent with approaching ‘peak’

conditions (i.e. low taxa richness and elevated abundances). The overall ES scores

for both the Pen 1 and Pen 2 stations were comparable to those recorded in the

previous monitoring round (ES 5.5 ± 1.1 and ES 4.9 ± 0.2, respectively; Table 10).

The overall ES score at the 50 m station was 3.1 (± 0.4), representing no change from

the previous monitoring round (ES 3.1 ± 0.6; Table 10). This result was again largely

due to deteriorated sediment chemistry (redox potential noticeably reduced and

moderately elevated sulphides; Figure 21). Organic matter was slightly elevated

compared to reference conditions. While total abundances and taxa richness were

similar to reference conditions, community composition was marginally affected (i.e.

slightly higher AMBI biotic coefficient and slightly lower M-AMBI ecological quality

ratio scores7). The overall ES score at the 150 m station was similar to reference

conditions (ES 2.2 ± 0.3), with all indicator variables comparable. Both stations are

within their respective assumed ES under the consent. The 150 m station was also

within the allowable ES for the OLE in the context of the BMP guidelines. Both total

abundance (13-28 individuals per core) and taxa richness (7–12 taxa per core) were

considerably lower than normal for the QC-Ctl-1 station, resulting in a higher ES score

than normal for this site. It is unclear what is driving this, however, inter-annual

variation at the control sites can also be expected to some degree. A full breakdown

of indicator variable contributions is provided in Appendix 7.

6 Refers to the declining side of peak abundance (where waste assimilation is theoretically maximal). 7 Refer to the MEMAMP for an explanation of each of the biotic indices.


33

Table 9. Average Enrichment Stage (ES) values and 95% confidence intervals (95% CI) calculated for indicator variables, and overall, for each Otanerau Bay (OTA) station (October 2018). See Appendix 7 for a full breakdown of indicator variable contributions. Both the assumed ES and the allowable ES under the BMP guidelines (MPI 2015) are shown for context.

Summary of indicator variables ES

(95% CI)

Pen 1 Organic matter (%OM) elevated in two samples.

Redox variable (one replicate negative), sulphides

elevated (particularly high for one replicate). Total

abundance moderately high (161-752 individuals

per core) and taxa richness low (3-8 per core).




Overall: 5.5 (0.4)

Pen 2 %OM elevated, redox slightly negative, and

sulphides elevated in all samples. Total abundance

moderately high (254-1,706 individuals per core),

and taxa richness low (7-11 taxa per core).




Overall: 5.0 (0.5)

Assumed ES < 6.0

BMP ES ≤ 5.0

50 m %OM slightly elevated, redox moderately negative,

sulphides moderately elevated but variable. Total

abundance (35-49 individuals per core) and taxa

richness (10-17 taxa per core) similar to reference

stations.




Overall: 3.1 (0.4)

Assumed ES ≤ 3.5

150 m

%OM, redox and sulphides comparable to

reference stations. Total abundance (24-52

individuals per core) and taxa richness (13-17 taxa

per core) comparable to reference stations.




Overall: 2.2 (0.3)

Assumed ES ≤ 2.5

BMP ES < 3.0

QC-Ctl-1 %OM slightly elevated (which can occur naturally).

Normal reference conditions redox and sulphides.

Total abundance (13-28 individuals per core) and

taxa richness (7-12 taxa per core) both lower than

normal for this station.




Overall: 2.7 (0.9)

QC-Ctl-2 Normal reference conditions.




Overall: 2.0 (0.2)


34


total free sulphides (µM), and macrofauna statistics for Otanerau Bay (OTA), October 2018. Error bars ± 1 SE, n = 3 samples each.


35

Table 10. Comparison of average overall Enrichment Stage scores at the Otanerau Bay (OTA) farm monitoring stations over the current and previous four assessments. Error bars represent ± 95% CI except in 2014 (± 1 SE).


2014 2015 2016 2017 2018

Pen 1 5.0 (0.0)* 5.9 (0.4)* 5.1 (0.3) 5.5 (1.1) 5.5 (0.4)

Pen 2 5.7 (0.0)* 5.6 (0.1)* 4.9 (0.2) 4.9 (0.2) 5.0 (0.5)

Pen 3 4.8 (0.4)* 4.8 (0.1)* 5.1 (0.0) 5.0 (0.0) -

50 m (Zone 1-2 boundary) 3.5 (0.4)* 3.2 (0.1)* 2.9 (0.3) 3.1 (0.6) 3.1 (0.4)

150 m (Zone 2–3 boundary) 2.2 (0.1)* 2.3 (0.1)* 2.2 (0.3) 2.4 (0.2) 2.2 (0.3)

QC-Ctl-1 2.0 (0.0) 2.2 (0.0) 2.4 (0.0) 2.4 (0.2) 2.7 (0.9)

QC-Ctl-2 2.0 (0.1) 1.8 (0.0) 2.0 (0.2) 2.3 (0.0) 2.0 (0.2)

* Note difference in location compared to subsequent three years


The overall average total recoverable copper concentration across all pen stations

was 84.3 ± 12 mg/kg (n = 6; Table 11), slightly exceeding the ISQG-Low threshold of

65 mg/kg. While still relatively high, this represents a considerable reduction in total

recoverable copper concentrations at this site since the previous monitoring (overall

pen average in 2017: 507.1 ± 330.3 mg/kg; see Fletcher et al. 2018). Dilute-acid-

extractable copper concentrations (a surrogate for bioavailability; ANZECC 2000)

were below the ISQG-Low criterion for all replicate samples. As such, it appears that

the copper beneath the net pens may be bound in particulate form, and ecological

effects are therefore not likely.

Total recoverable zinc concentrations were above the ISQG-Low criterion (200 mg/kg;

Table 11) in all samples, with two replicates also exceeding the ISQG-High threshold

(410 mg/kg). The overall pen average was slightly below the ISQG-High threshold

(393.3 ± 19.4 mg/kg). Dilute-acid-extractable zinc concentrations (a surrogate for

bioavailability; ANZECC 2000) were above the ISQG-Low criterion in all replicate

samples (200 mg/kg; Table 11). The relatively high overall pen average for dilute-acid-

extractable zinc indicates localised biological effects are possible from zinc at this site.

There had been a general trend of decreasing total recoverable zinc levels at the OTA

site in the period 2013-2015; however, the results of the last two rounds of monitoring

represent a noticeable increase in zinc levels (see Appendix 5).


36

Table 11. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Otanerau Bay (OTA) pen samples, October 2018. Pen and overall averages (± SE) are also shown. The ISQG threshold values are for both recoverable and extractable forms for each metal. Bold values exceed ANZECC (2000) ISQG-Low, and underlined values exceed ISQG-High.

Sample Total

recoverable copper


copper

Total recoverable zinc


zinc

Pen 1 a 78.0 12.1 430.0 270.0

b 101.0 16.7 370.0 270.0

c 113.0 19.0 340.0 280.0

Pen 1 average 97.3 (± 10.3) 15.9 (± 2.0) 380.0 (± 26.5) 273.3 (± 3.3)

Pen 2

a 55.0 18.7 370.0 260.0

b 46.0 18.4 380.0 230.0

c 113.0 24.0 470.0 330.0

Pen 2 average 71.3 (± 21.0) 20.4 (± 1.8) 406.7 (± 31.8) 273.3 (± 29.6)






Figure 19). Water depth along Transect 1 transitioned from 9 to 24 m, while Transect

2 from 4 to 27 m depth. The substrate along the shallow portions of Transect 1 was

predominantly comprised loose cobble with considerable coverage of crustose

coralline algae. Patches of sand interspersed with shell hash became more common

with increasing water depth. Occasionally, microalgal (diatom) mats were observed as

well as drift algae (Ulva sp.) in the shallow portion of the transect, interspersed with

larger brown algae (Undaria pinnatifida and Carpophyllum maschalocarpum).

Substrates along Transect 2 were similar to Transect 1, with the addition of the

presence of small boulders largely covered in crustose coralline algae in shallow

water.

Both transects had similar epifauna present, including kina (Evechinus chloroticus),

brittle stars (Ophiopsammus maculata), cushion stars (Patiriella regularis), sea

cucumbers (Australostichopus mollis), hydroids, eleven-armed sea stars

(Coscinasterias calamaria), calcareous tubeworms, horse mussels (Atrina zelandica)

and colonial ascidians or sponges. Epifauna were largely confined to initial, shallow

portions of the transects, apart from kina in Transect 1 which were abundant

throughout. Triplefins (probably Forsterygion lapillum), spotties (Notolabrus celidotus)

and blue cod (Parapercis colias) were observed along Transect 1. Large purple


37

barrel-shaped sponges were also observed in deeper habitats along Transect 2.

Overall, no signs of excessive deposition, nutrient enrichment or other obvious

changes in visual characteristics of the inshore habitats were observed.

5.7. Water column

Water column monitoring at only one pen station was required by the MEMAMP,

however two are reported here as additional data were collected (Figure 22). Water

temperatures were in general greater near the surface than in deeper waters at all

stations. Stratification was apparent at 2–3 m in salinity profiles, with variation in

salinity down to 10 m at a number of stations, and a minor low-salinity layer apparent

down to nearly 20 m at the control station (QC-Ctl-2).

Chlorophyll-a (chl-a) concentrations (a proxy for phytoplankton biomass) increased

through the first half of the water column, and were relatively constant from midwater

to the seabed at most stations. The exception was Pen 1, where chl-a concentrations

were similar throughout the water column. Any increase in phytoplankton biomass as

a result of finfish aquaculture would occur after a time lag (as phytoplankton grow in

response to increased nutrients) and would therefore not be apparent at the pen

stations, but further afield. Therefore, this difference is likely to be the result of

chance, rather than the result of nutrient additions at the pen.

At the Pen 1 stations, and to a lesser extent at Pen 2 and the 50 m stations, dissolved

oxygen (DO) concentrations were lower mid-water. This is consistent with fish

respiration reducing the concentration of oxygen in the water column. Moreover, near-

bed DO was lowest just above the seabed at Pen 1, where concentration dropped to

just below 6 mg/L (69.3% saturation). Near-seabed concentrations were greater at

Pen 2 and progressively increased with distance from the pens, with the highest

values at the control station (QC-Ctl-2). This suggests the farm is also causing lower

water column DO due to biological activity associated with seabed enrichment. A

surface layer of low DO was also apparent, however this occurred at all stations, and

is therefore not farm-related.

Turbidity increased markedly near the seabed at Pen 1 and, to a lesser extent, Pen 2.

This is likely to be due to resuspension of fine particles that had settled on the

seabed, although increases higher in the water column, particularly at Pen 2, may be

associated with particulate material falling from the farm at the time of sampling.


38

Figure 22. Chlorophyll-a (chl-a), salinity, temperature and turbidity (optical back-scatter; OBS), as measured by a sensor array raised through the water column, at the Otanerau Bay (OTA) farm sites and the QC-Ctl-2 station, October 2018. QC-Ctl = Queen Charlotte Control.


39

6. RUAKAKA BAY


The RUA farm was established in 1985. Water depth at the site is c. 35 m, with the

net pens extending from the surface to a depth of c. 20 m. The site has an average

water current speed of 3.7 cm/s.

Since 2005, feed inputs have ranged from 1,661 to 3,206 tonnes per annum

(Figure 23). A total of 1,677 tonnes of feed was used over the 12-month period prior to

this year’s monitoring (November 2016 through October 2017). This is approximately

900 tonnes less than the total feed discharged during the previous 12-month period

(note this time period differs from that shown in Figure 23 and Figure 24 which show a

period that allows historical comparisons). Feed discharge was relatively continuous

throughout the 12 months preceding monitoring; feed loadings peaked in October

2018 and were lowest in February 2018 (Figure 24).

Figure 23. Annual feed inputs (December through November) at the Ruakaka Bay (RUA) salmon farm, 2005–2018. Feed input data provided by NZ King Salmon.


40

Figure 24. Monthly feed inputs at the Ruakaka Bay (RUA) salmon farm from December 2017 to



Sampling for the RUA annual monitoring was undertaken on 26 and 27 October 2018,

using the techniques summarised in Appendices 1-3.

Sampling stations are shown in Figure 25. The location of the farm structures had not

changed since the previous annual monitoring. Video footage for inshore habitat

assessments was collected along two transects using a towed drop-camera set-up

with a surface image feed. Transects ran from the shore toward the net pens and

followed those surveyed in 2014 and 2016 (see Figure 25). Water column monitoring

was carried out at all farm stations as well as the QC-Ctl-3 station. There were no

variations to the typical sampling procedure as set out in the MEMAMP (Newcombe &

Elvines 2018).


41

Figure 25. Soft-sediment sampling locations at the Ruakaka Bay (RUA) salmon farm site. ‘QC-Ctl’ = Queen Charlotte Sound Control. Position accuracy is ± 5 m.


Video footage of the seabed from the pen stations showed soft, dark muddy

sediments with minor shell and biofouling debris on the seafloor (see Figure 26).

Beggiatoa-like bacteria was present on shell edges and on the sediment surface at

both pen stations, however there was no evidence of outgassing at either station.

Several egg casings were present at Pen 1, and anemones and minor shell debris

were common at both pen stations.

The sediment at the 50 m and 150 m stations was lighter in colour and less flocculant

than the pen stations. Burrow holes (some with polychaete worm tentacles visible)

and trail marks were present at both stations. Polychaete worms (likely Dorvilleidae or

Capitella sp.) were observed moving on the surface of the substrate. Two spiny

dogfish (Squalus acanthias) were seen at the 50 m station. Substrates from the

seabed at the reference stations appeared generally similar to the 50 m and 150 m

stations with predominantly soft muddy sediments. Burrow holes and trail marks were

evident at both stations. There were no notable epifauna at the reference stations.


42

Figure 26. Representative images of the seafloor at each of the Ruakaka Bay (RUA) salmon farm monitoring stations, October 2018.


43


The seabed at the pen stations showed moderate to high enrichment (ES 3.7-4.8;

Table 12); however, a decrease in the ES score from the last year’s monitoring round

is noted (Pen 1: ES 5.0 ± 0.6 and Pen 2: ES 5.1 ± 0.2; Table 13). Conditions at the

Pen 1 station have improved considerably with a transition from a ‘peak-of-

opportunist’ stage to a ‘pre-peak-of-opportunist’ stage. While sulphide measurements

were highly elevated in the current round of monitoring (1,121-1,531 µM),

improvements in both organic matter and redox potential were noted (Figure 27).

Total abundances were elevated (1,206-3,791 individuals per core) but associated

taxa richness was high (18-28 taxa per core).

Conditions at the Pen 2 station highlight that high levels of enrichment remain at this

site. Organic matter was highly elevated, particularly in one replicate sample (16.7%

AFDW). Redox potential was reduced and sulphide measurements moderately

elevated across all three samples (Figure 27). Macrofaunal community measures

indicated communities to be at the ‘peak-of-opportunist’ stage, with mostly low taxa

richness (8–16 taxa per core) and high total abundances (1,610–3,297 individuals per

core). Macrofauna communities at the Pen 2 station were dominated by opportunist

taxa (e.g. capitellids, and to a lesser extent, nematode worms). Both Pen stations

were within the assumed ES for this zone (i.e. ES < 6.0) and both were compliant in

the context of the BMP guidelines (i.e. ES ≤ 5.0).

The seabed at the 50 m station showed moderate enrichment (ES 3.1 ± 1.2), with a

noticeable increase in ES score since the previous monitoring round (ES 2.5 ± 0.4;

Table 13). This increase was largely driven by a deterioration in sediment chemistry

indicators, with reduced redox potential and moderately elevated sulphide

measurements across all three samples (Figure 27). Total abundances and taxa

richness were low in one replicate sample (13 individuals, representing 7 taxa);

however, macrofaunal indicators for the remaining two replicates were normal. The

50 m station was within the assumed ES under the consent.

The seabed at the 150 m station also showed moderate enrichment (ES 2.9 ± 0.5),

with an increase in associated ES score since the previous monitoring round (ES

2.5 ± 0.4; Table 13). While organic matter and redox potential were comparable with

reference stations, sulphide measurements were moderately elevated in one replicate

sample. While total abundances and taxa richness were largely similar to reference

conditions, community composition was marginally different (i.e. slightly higher AMBI

biotic coefficient and slightly lower M-AMBI ecological quality ratio scores than what

would normally be considered reference). The 150 m station exceeded the allowable

ES under the resource consent (i.e. ES ≤ 2.5), however, it would be compliant for this

zone under the BMP guidelines (i.e. ES < 3.0). Similar to the QC-Ctl-1 station, both

total abundance (8-18 individuals per core) and taxa richness (4-11 taxa per core)

were considerably lower than normal for the QC-Ctl-4 site, resulting in a higher ES


44

score then normal for this site. It is again unclear what is driving this, however, inter-

annual variation at the control sites can also be expected to some degree. A full

breakdown of indicator variable contributions is provided in Appendix 8.

Table 12. Average Enrichment Stage (ES) values and 95% confidence intervals (95% CI)

calculated for indicator variables, and overall, for each Ruakaka Bay (RUA) station (October 2018). See Appendix 8 for a full breakdown of indicator variable contributions. Both the assumed ES and the allowable ES under the BMP guidelines (MPI 2015) are shown for context.

Summary of indicator variables ES (95% CI)

Pen 1

Organic matter (%OM) variable (elevated in one replicate), redox normal, and sulphides moderately elevated. Total abundance elevated (1,206-3,791 individuals per core) but taxa richness high (18-28 taxa per core).




Overall: 3.7 (0.1)

Pen 2

%OM elevated but variable (particularly high in one replicate), redox reduced (slightly negative in two replicates), and sulphides moderately elevated. Total abundance elevated (1,610-3,297 individuals per core) and taxa richness low (8-16 taxa per core).




Overall: 4.8 (0.5)

Assumed ES < 6.0

BMP ES ≤ 5.0

50 m

%OM normal, redox variable (negative in two replicates). Sulphides moderately elevated. Total abundance variable, particularly low in one replicate (13-236 individuals per core). Taxa richness low in same replicate, otherwise normal (7-33 taxa per core).




Overall: 3.1 (1.2)

Assumed ES ≤ 3.5

150 m

%OM and redox normal, sulphides moderately elevated in one replicate. Total abundance slightly elevated (40-307 individuals per core). Taxa richness slightly reduced in one replicate (11-32 taxa per core).




Overall: 2.9 (0.5)

Assumed ES ≤ 2.5

BMP ES < 3.0

QC-Ctl-3

Normal background conditions with reference to %OM, redox and sulphides. Both total abundance (17-29 individuals per core) and taxa richness (12-17 taxa per core) slightly lower than normal for this site.




Overall: 2.2 (0.1)

QC-Ctl-4 Slightly elevated %OM (which is typical of this site). Both total abundance (8-18 individuals per core) and taxa richness (4-11 taxa per core) considerably lower than normal for this site.




Overall: 3.2 (0.7)


45


total free sulphides (µM), and macrofauna statistics for Ruakaka Bay (RUA), October 2018. Error bars = ± 1 SE, n = 3 samples.


46

Table 13. Comparison of average overall Enrichment Stage scores at the Ruakaka Bay (RUA) farm monitoring stations over the current and previous four assessments. Error bars represent ± 95% CI except in 2014 (± 1 SE).


2014 2015 2016 2017 2018

Pen 1 4.0 (0.0) 5.3 (0.1) 5.1 (0.0) 5.0 (0.6) 3.7 (0.1)

Pen 2 5.6 (0.1) 5.3 (0.3) 5.7 (0.1) 5.1 (0.2) 4.8 (0.5)

50 m (Zone 1-2 boundary) 2.4 (0.1) 2.3 (0.2) 2.7 (0.7) 2.5 (0.4) 3.1 (1.2)

150 m (Zone 2–3 boundary) 2.1 (0.1) 2.0 (0.1) 2.1 (0.0) 2.5 (0.4) 2.9 (0.5)

QC-Ctl-3 2.1 (0.0) 1.8 (0.3) 2.0 (0.2) 2.2 (0.2) 2.2 (0.1)

QC-Ctl-4 2.1 (0.0) 2.0 (0.3) 2.1 (0.1) 2.5 (0.2) 3.2 (0.7)


Total recoverable copper levels beneath pens at the RUA site exceeded the

ISQG-Low trigger level (65 mg/kg; ANZECC 2000) in two of the six replicates

(Table 14). However, the overall pen average was below this threshold (44 ±

11.2 mg/kg, n = 6). Dilute-acid-extractable copper concentrations (a surrogate for

bioavailability; ANZECC 2000) were well below the ISQG-Low trigger level across all

replicates (4.1–14 mg/kg; Table 14). As such, no ecological effects of copper in the

sediments are expected.

The concentration of total recoverable zinc exceeded the ISQG-High trigger level

(410 mg/kg) in two of the six replicates, with a further two replicates also exceeding

the ISQG-Low threshold (200 mg/kg; Table 14). Dilute-acid-extractable zinc

concentrations were below the ISQG-Low trigger level in all Pen 1 replicates;

however, concentrations exceeded this threshold in all Pen 2 replicates (Pen 2c also

exceeded ISQG-High). Localised ecological effects of zinc in the sediments are

therefore possible at the Pen 2 station. The overall pen average for dilute-acid-

extractable zinc was above ISQG-Low, and higher than that recorded in the previous

monitoring round.

The results of the current monitoring represent a slight increase in total recoverable

zinc since the previous year. This is in contrast to the general trend of decreasing total

recoverable zinc levels at RUA since 2013 (see Appendix 5).


47

Table 14. Copper and zinc concentrations (mg/kg dry weight) in bulk sediment from Ruakaka Bay (RUA) pen samples, October 2018. Pen and overall averages (± SE) are also shown. Bold values exceed ANZECC (2000) ISQG-Low, and underlined values exceed ISQG-High.

Sample

Total recoverable

copper


copper

Total recoverable

zinc


zinc

Pen 1

a 31.0 8.8 141.0 85.0

b 22.0 4.1 250.0 84.0

c 12.1 4.2 121.0 53.0

Pen 1 average 21.7 (± 5.5) 5.7 (± 1.6) 170.7 (± 40.1) 74.0 (± 10.5)

Pen 2

a 69.0 13.7 380.0 360.0

b 48.0 12.7 460.0 350.0

c 82.0 14.0 520.0 440.0

Pen 2 average 66.7 (± 9.6) 13.5 (± 0.4) 453.3 (± 40.6) 383.3 (± 28.5)






Figure 25). Substrates in the shallow end of Transect 1 comprised predominantly of

cobble habitat with considerable encrusting coralline and brown algae. Scattered

clumps of brown foliose algae were observed. Sand patches were intermittent, with

substrates transitioning to coarse sand and shell hash, followed by more gravelly

substrates, as water depth increased. A layer of fine sediment covered the coarser

substrate and biogenic structures (such as shell debris) present on the seafloor as

proximity to the farm structures increased. The substrate along Transect 2 was similar

to Transect 1, with sparse clumps of brown foliose algae present. A fine layer of

sediment was again present in deeper water, nearby to the farm structures.

Both transects had similar epifauna present. Invertebrate species included kina

(Evechinus chloroticus), brittle stars (Ophiopsammus maculata), cushion stars

(Patiriella regularis), sea cucumbers (Australostichopus mollis), hydroids, eleven-

armed sea stars (Coscinasterias calamaria) and colonial ascidians or sponges.

Occasional dense patches of anemones were present in both transects. Large

calcareous tubeworms were abundant on rocks and mussel shell surfaces. In

addition, horse mussels (Atrina zelandica) were occasionally seen in deeper, sandy

habitats along with solitary sea squirts (likely Cnemidocarpa sp.). Finger sponges

were also observed along Transect 2 only. In general, no signs of excessive

deposition, nutrient enrichment or other obvious changes in visual characteristics of

the inshore habitats were observed.


48

6.7. Water column

Only one pen station was required by the MEMAMP; however, two are reported here

as additional data were collected (Figure 28). Surface temperatures generally

declined steadily with depth, although a slightly cooler layer was present in the top few

metres at stations away from the farm. It is possible that farm structures have caused

mixing of this surface layer, although this cooler layer was also observed near-farm at

the OTA site (see Section 5.7). Stratification was apparent at 2–3 m in the salinity

profiles, with minor variation in salinity apparent throughout the water column at most

stations.

Chlorophyll-a (chl-a) concentrations (a proxy for phytoplankton biomass) generally

declined with depth, with the greatest peak of approximately 2 µg/L apparent between

5 and 10 m at the control station (QC-Ctl-3).

Dissolved oxygen (DO) showed some reduction in surface to mid-waters at the Pen 2

station, but there was nothing to indicate an effect of finfish aquaculture in mid-waters

or at the seabed. Similarly, turbidity did not appear to differ based on proximity to the

pens. Based on the above observations, no clear farm-related effects on the water

column were apparent.


49

Figure 28. Chlorophyll-a (chl-a), salinity, temperature and turbidity (optical back-scatter; OBS), as

measured by a sensor array raised through the water column, at the Ruakaka Bay (RUA) farm sites and the QC-Ctl-3 station, October 2018. QC-Ctl = Queen Charlotte Control.


50

7. SUMMARY AND RECOMMENDATIONS FOR ALL SITES

This section provides a site-specific summary with recommendations (where

applicable) for each of the four surveyed farm sites. Key findings for specific indicators

are italicised. In the context of the BMP guidelines, there are four levels of response

possible depending on the assessment of overall ES score within each zone. These

are termed: ‘alert’, ‘minor action level’, ‘major action level’, and ‘destocking’ (see MPI

2015). The severity of the required management response increases in response to

the assessed level of overall Enrichment Stage. An overview of compliance, according

to both the consent conditions (i.e. compliant or not compliant) and in context of the

BMP guidelines (i.e. compliant or required action level), for all sites is provided in

Table 15.

7.1. Forsyth Bay

The FOR site has been vacant since mid-January 2016, thus no feed has been

discharged at the site for almost three years prior to this monitoring. Observations of

environmental effects were as follows:

• Seabed enrichment beneath the previous pen area was well within the allowable

ES under the BMP guidelines, and the assumed ES under the present resource

consent. Macrofaunal indicators have shown a marked improvement, although the

prevalence of opportunistic taxa is still high in some areas. Both pen stations have

very high organic matter and poor sediment chemistry across several replicate

samples.

• No ecological effects are expected from copper present in the sediments. The

copper beneath the previous pen position is likely to be bound in particulate form.

Dilute-acid-extractable copper concentrations were below the threshold for

possible biological effects across all replicate samples.

• Potentially bio-available zinc levels continue to exceed the threshold for probable

biological effects. Concentrations of potentially bio-available zinc within sediments

beneath the previous pen position have approximately doubled since the previous

monitoring round, despite no additional feed inputs.

• No signs of excessive deposition, nutrient enrichment or other obvious changes in

visual characteristics of the inshore habitats were observed on either transect.

• Water column measurements did not indicate impacts of farming activities due to

enrichment-related processes. No significant reductions of near-bottom DO or

increases in turbidity associated with the farm were apparent.

The sediments at this site are still clearly impacted by recalcitrant material deeper in

the sediment profile, and by high levels of zinc contamination. While some

improvements in sediment characteristics are evident, it appears these may be


51

restricted to the surface layers. It is likely that organic enrichment effects will persist

until remediation is undertaken. We recommend additional monitoring at the FOR site

in response to zinc levels to better understand the mechanism for this increasing

contamination. Further, we do not recommend that the FOR site is restocked until

these issues are resolved due to the present compromised ability of the site to

assimilate organic waste.

7.2. Waihinau Bay

The WAI site was fallowed for ~4 of the 12 months preceding monitoring (from

January to late April 2018). A total of 1,830 tonnes of feed was discharged over the

12-month period prior to monitoring. Feed discharge was considerably higher (c. 879

tonnes) in 2018, compared to the previous 12-month period. Observations of

environmental effects were as follows:

• Enrichment levels at the pen stations were within the assumed ES under the

resource consent. However, in the context of the BMP guidelines, seabed

enrichment at the Pen 1 station would elicit an ‘alert’ management response. The

seabed beneath the WAI farm is very highly enriched, with both sampling stations

indicating ‘peak’ macrofaunal conditions. Very high abundances of opportunistic

taxa (e.g. capitellid and nematode worms) were present across all replicate

samples.

• Seabed enrichment at the 180 m station was within the industry operational goal

in the context of the BMP guidelines. However, similar to the previous two

monitoring assessments, slightly impacted sediment chemistry and marginally

altered community composition were noted.

• No ecological effects are expected as a result of copper in the sediments. The

copper beneath the net pens is likely to be bound in particulate form. Dilute-acid-

extractable copper concentrations were below the threshold for possible biological

effects across all replicate samples.

• Moderately high levels of potentially bio-available zinc within sediments means

that localised biological effects are possible. There has been a considerable

reduction in bio-available zinc concentrations since the previous monitoring round.

• High levels of filamentous algae were recorded on one inshore transect, however

these conditions cannot be attributed to farm-related activities. No other signs of

excessive deposition, nutrient enrichment or other obvious changes in visual

characteristics of the inshore habitats were observed.


enrichment-related processes. Minor increases in turbidity and reductions in near-

bottom DO concentrations were recorded at the pen stations; however, this was

consistent across farm and reference stations.


52

7.3. Otanerau Bay

The OTA site was fallowed for ~4 of the 12 months preceding monitoring (from

mid-January to mid-April 2018). A total of 1,376 tonnes of feed was discharged over

this time. Feed discharge was slightly higher (c. 190 tonnes) in 2018, compared to the

previous 12-month period. Observations of environmental effects were as follows:

• Enrichment levels at the pen stations were within the assumed ES under the

resource consent. However, in the context of the BMP guidelines, seabed

enrichment at the Pen 1 station would require the two archive samples to be

processed before compliance could be determined. Macrofaunal conditions

appear to be deteriorating beyond from ‘peak-of-opportunist’ levels, with reduced

abundances and low taxa richness. Trace coverage of bacteria and outgassing

from the seabed were also noted during video assessments.

• Enrichment levels at both the 50 m and 150 m stations have remained largely

constant over the past 12 months. Both scores are within the assumed ES

allowable under the consent, and the 150 m station is within the ES in the context

of the BMP guidelines. The 50 m station showed deteriorated sediment chemistry.





• Potentially bio-available zinc levels exceeded the threshold for possible biological

effects at both pen stations. Concentrations of potentially bio-available zinc within

sediments have increased since the previous monitoring round.



• Water column measurements indicated localised impacts of farming activities due

to enrichment-related processes. Decreases in water column DO and increases in

turbidity were recorded at the pen stations, and to a lesser extent at the 50 m

station.

As per the BMP, it is recommended that archive samples from the Pen 1 station are

processed for greater certainty around enrichment conditions at this station.

7.4. Ruakaka Bay

The RUA site was operational during all 12 months prior to monitoring. A total of 1,677

tonnes of feed was discharged over this period, a considerable reduction (c. 900

tonnes) since the previous 12-month period. Observations of environmental effects

were as follows:


53

• The ES scores at the pen stations were within the assumed ES under the

resource consent and in the context of the BMP guidelines. There has been an

improvement in ES scores at both stations, in particular at Pen 1. Organic loading

and macrofaunal indicators remain high at the Pen 2 station. Trace coverage of

bacteria was also noted during video assessments.

• The 50 m station showed moderate seabed enrichment; however, enrichment

levels were within the assumed ES under the resource consent.

• Moderate seabed enrichment was also evident at the 150 m station. In the context

of the BMP guidelines, this station would be within the allowable ES for the outer

limit of effects (OLE; ES < 3.0). However, when assessed under the more

conservative assumed ES under the resource consent, the 180 m station

exceeded the maximum enrichment level (i.e. > ES 2.5) so would be deemed to

be non-compliant. Enrichment at the 150 m station was evident as slightly poorer

sediment chemistry and marginally higher macrofaunal abundances.





• Potentially bio-available zinc levels exceeded the threshold for possible biological

effects at the Pen 2 station. Concentrations of potentially bio-available zinc within

sediments have increased since the previous monitoring round, and localised

effects are possible.




enrichment-related processes. No significant reductions of near-bottom DO or

increases in turbidity associated with the farm were apparent.

We recommend that feed input at the RUA sites remains at the current levels to allow

further recovery of the sediments at the pen and outer stations.


54

Table 15. Overview of New Zealand King Salmon ‘low-flow’ salmon farm compliance in the context of the assumed Enrichment Stage of the consent, and the best management practice guidelines (BMP; MPI 2015). Green cells indicate compliance, orange cells indicate some degree of non-compliance (see MPI 2015). DAE = concentration of the dilute-acid-extractable fraction. Stations where monitoring was not undertaken are indicated by N/A.

Pen 1 Pen 2 Pen a-d

Transition

zone Outer zone

Compliance according to assumed ES under the consent

Forsyth Bay N/A Compliant Compliant N/A N/A

Otanerau Bay Compliant Compliant N/A Compliant Compliant

Ruakaka Bay Compliant Compliant N/A Compliant Not compliant

Compliance in the context of the BMP guidelines

Forsyth Bay

Enrichment N/A Compliant Compliant - N/A

Copper N/A Compliant - N/A

Zinc N/A Mean DAE > ISQG-High - N/A

Waihinau Bay

Enrichment Alert Compliant N/A - Compliant

Copper Compliant N/A - N/A

Zinc Compliant Mean DAE >

ISQG-Low N/A - N/A

Otanerau Bay

Enrichment TBD* Compliant N/A - Compliant


Zinc Mean DAE > ISQG-Low N/A - N/A

Ruakaka Bay

Enrichment Compliant Compliant N/A - Compliant


Zinc Compliant Mean DAE >

ISQG-Low N/A - N/A

* Station compliance cannot be determined until additional archive samples are processed.

- No Enrichment Stage standards are specified for the transition zone under the BMP guidelines.


55

8. ACKNOWLEDGEMENTS

Sincere thanks are expressed to Scott Edhouse, James Brodie, Luke Ogilvy, Rob

Major and the Cawthron Taxonomy Lab for contributions to associated fieldwork and

sample processing.

9. REFERENCES

ANZECC 2000. Australian and New Zealand guidelines for fresh and marine water

quality 2000 Volume 1. National Water Quality Management Strategy Paper

No. 4. Australian and New Zealand Environment and Conservation Council

and Agriculture and Resource Management Council of Australia and New

Zealand, Canberra.

Fletcher L, Atalah J, Elvines D 2018. Annual environmental monitoring at the Forsyth

Bay, Waihinau Bay, Otanerau Bay and Ruakaka Bay salmon farms 2017.

Prepared for The New Zealand King Salmon Co. Ltd. Cawthron Report No.

3124. 59 p. plus appendices.

Keeley N 2012. Assessment of enrichment stage and compliance for salmon farms–

2011. Prepared for New Zealand King Salmon Co. Ltd. Report No. 2080. 15 p.

Keeley NB, Cromey CJ, Goodwin EO, Gibbs MT, Macleod CM 2013. Predictive

depositional modelling (DEPOMOD) of the interactive effect of current flow and

resuspension on ecological impacts beneath salmon farms. Aquaculture

Environment Interactions 3(3): 275-291.

Keeley N, Macleod C, Forrest B 2012. Combining best professional judgement and

quantile regression splines to improve characterisation of macrofaunal

responses to enrichment. Ecological Indicators 12: 154-166.

MPI 2015. Best Management Practice guidelines for salmon farms in the Marlborough

Sounds: Benthic environmental quality standards and monitoring protocol.

Prepared by the Benthic Standards Working Group. 43 p.

Nelson WA 2013. New Zealand seaweeds: An illustrated guide. Te Papa Press,

Wellington.

Newcombe E, Elvines D 2018. Marine environmental monitoring – adaptive

management plan for salmon farms: Forsyth, Waihinau, Otanerau and

Ruakaka (2018-2019). Prepared for the New Zealand King Salmon Company

Ltd. Cawthron Report No. 3237. 12 p. plus appendices.

Pochon X, Atalah J, Wood SA, Hopkins GA, Watts A, Boedeker C 2015. Cladophora

ruchingeri (C. Agardh) Kützing, 1845 (Cladophorales, Chlorophyta): a new

biofouling pest of green-lipped mussel Perna canaliculus (Gmelin, 1791) farms

in New Zealand. Aquatic Invasions 10: 123–133.


56

10. APPENDICES

Appendix 1. General methods for soft-sediment sampling.

A1.1 Sampling locations

Sampling stations are generally allocated as follows (see map in each site section for

exact locations):

• Net pen stations, within the zone of maximal effect. These are typically sampled

below the edge of the net pen.

• 50 m and 150-180 m from the edge of the net pen, respectively. At low-flow sites,

the sampling direction is not critical as footprint deformity is typically low.

• Reference or ‘control’ stations. Typically, there is at least one near to the farm and

one in the far-field, consistent with the BMP guidelines.

A1.2 Environmental variables

Three replicate sediment grab samples were collected at each sampling station using

a van Veen grab. Each grab sample was examined for sediment colour, odour, texture

and bacterial mat coverage. The top 30 mm of one sediment core (63 mm diameter)

was analysed for organic matter (as % ash-free dry weight; AFDW), redox potential

(EhNHE, mV), and total free sulphides (µM). Samples from the pen stations were

analysed for copper and zinc concentrations (both total recoverable and dilute-acid-

extractable8). Laboratory analytical methods for sediment samples can be found in

Table A1.1.

A separate core (130 mm diameter, approx. 100 mm deep) was collected from each

grab for macrofauna9 identification and enumeration. Samples were sieved through

0.5 mm mesh before processing. Raw macrofauna data were further analysed to

calculate the total abundance (N/core), total number of taxa (S/core), Shannon-

Weiner diversity index (H’), Pielou’s evenness index (J’), Margalef richness index (d),

AMBI biotic coefficient and M-AMBI ecological quality ratio. Refer to the MEMAMP for

an explanation of each of the biotic indices.

Two additional replicate samples (‘d’ and ‘e’ replicates) were taken for redox, organic

matter and macrofauna from each net pen station and were archived in case further

certainty is required for compliance purposes.

Video footage was also collected at each station to qualitatively assess bacterial mat

coverage, general seabed condition and presence of sediment out-gassing. The sea

8 ANZECC threshold values are based on the bio-available fraction. For sediment particulates, the dilute-acid-

extractable (1M HCl) fraction is used as a surrogate for bio-availability (ANZECC 2000). 9 The term ‘macrofauna’ describes animals buried in the sediment.


57

surface was also scanned for visible sediment out-gassing as this could provide

further evidence of particularly enriched conditions. General observations of epibiota

were also made.

Table A1.1 Laboratory analytical methods for sediment samples processed by Hill Laboratories (a) or Cawthron Institute (b).

Analyte Method Default detection limit

Organic matter (as ash-free dry weight) a

Ignition in muffle furnace 550°C, 6hr, gravimetric. APHA 2540 G 22nd ed. 2012. Calculation: 100 – Ash (dry wt).

0.04 g/100 g

1M HCl extractable copper & zinc a

< 2 mm sieved fraction, 1M HCl extraction, ICP-MS. CSIRO 2005.

1.2 mg/kg (copper) 3 mg/kg (zinc)

Total recoverable copper & zinc a

Dried sample. Nitric/ hydrochloric acid digestion, ICP-MS, trace level. US EPA 200.2.

0.2-2 mg/kg (copper)

0.4-4 mg/kg (zinc)

Total free sulphides b Cawthron Protocol 60.102. Sample solubilised in high pH solution with chelating agent and anti-oxidant. Measured in millivolt (mV) using a sulphide specific electrode and calibrated using a sulphide standard.

A1.3 Assessment of Enrichment Stage (ES)

Seabed condition can be placed along an enrichment gradient that has been

quantitatively defined according to Enrichment Stage (ES). The ES assessment

references a selection of informative chemical and biological indicator variables10.

For each indicator variable (raw data), an equivalent ES score is calculated using

previously described relationships (MPI 2015). Average ES scores were then

calculated for the sediment chemistry variables (redox and sulphides), the

macrofauna composition variables (abundance, richness, evenness, diversity and

biotic indices), and organic matter (% AFDW). The overall ES for a given sample was

then calculated by determining the weighted average11 of those three groups of

variables. Finally, the overall ES for the sampling station was calculated from the

average of the replicate samples with the degree of certainty reflected in the

associated 95% confidence interval.

10 There are risks associated with placing emphasis on any individual indicator variables of ES. This is particularly

true for chemical indicators, which tend to be more spatially and temporally variable. As such, the derived overall ES value is considered a more robust measure of the general seabed state.

11 Weighting used in the current assessment is the same as that used in previous years: organic loading = 0.1, sediment chemistry = 0.2, macrofauna composition = 0.7.


58

Appendix 2. General methods for inshore habitat assessments.

Farming sites at Forsyth, Waihinau, Otanerau and Ruakaka have no significant reef

habitats within their primary depositional footprint. However, inshore habitats are

qualitatively assessed for general health with respect to signs of excessive deposition,

nutrient enrichment and other obvious changes in visual characteristics over time.

This assessment is undertaken biennially and was last undertaken in 2016. Video

footage was collected using a towed drop-camera with a surface image feed. All

transects ran from the shore toward the net pens and followed those surveyed in 2014

and 2016. Footage was reviewed and compared with that collected during the

previous survey to assess any apparent changes.

Appendix 3. General methods for water column sampling.

Water column monitoring was carried out at the same time as the benthic monitoring

component. Stations monitored at each farm included one pen station (generally

Pen 1), as well as stations at the 50 m and 150-180 m station where applicable (i.e.

unless farms were fallowed or no 50 m station exists). Water column monitoring was

also carried out at two reference stations for each farm site for comparison.

At each station, salinity, temperature, fluorescence (a proxy for chlorophyll-a), optical

backscatter (a proxy for turbidity) and DO was measured in situ using a conductivity-

temperature-depth (CTD) instrument with an attached dissolved oxygen (DO) sensor.


59

Appendix 4. Full results for the Forsyth Bay (FOR) salmon farm. Table A4.1 Detailed Enrichment Stage (ES) calculations for each station at the Forsyth Bay salmon farm, October 2018. For details about how these values were

calculated see MPI (2015). Organic matter was not able to be calculated for one single replicate station (Pen c), thus the Overall ES score is assigned based on sediment chemistry and macrofauna values only (weightings 0.25 and 0.75, respectively).


60

Table A4.1 (cont.).


61

Table A4.2 Summary of the average (± SE) sediment physical and chemical properties, macrofauna variables and calculated indices for Forsyth Bay (FOR), October 2018. Number of asterisks indicate the number of samples used to derive the score (i.e. '*' is n = 1). Pen a-d were single replicate stations, so no error value is provided. Organic matter was not able to be calculated for one single replicate station (Pen c).

Station Units Pen 2 Pen a Pen b Pen c Pen d PS-Ctl-2 PS-Ctl-3

Depth m 32 32 32 32 32 32 36

Se

dim

en

ts

AFDW % 18.2 (0.7)*** 19.1* 20* - 7* 5.4 (0.0)*** 5.5 (0.1)***

Redox EhNHE, mV 5.3 (38.9)*** -41* -9* -104* 48* 152.3 (24.4)*** 178 (30.7)***

Sulphides µM 1238.6 (82.4)*** 1265* 1265* 1004* 738* 70 (0.0)*** 85.4 (15.4)***

Bacterial mat - No - - - - No No

Out-gassing - No No No No No No No

Odour - Moderate Moderate Strong Moderate Strong None None

Ma

cro

fau

na

sta

tis

tic

s

Abundance No./core 158.7 (29.7)*** 100* 175* 446* 1326* 56 (7.5)*** 70.7 (12.7)***

No. taxa No./core 19.3 (1.8)*** 14* 13* 24* 10* 23.3 (1.9)*** 20.7 (2)***

Evenness Stat. 0.7 (0.1)*** 0.8* 0.8* 0.6* 0.1* 0.9 (0.0)*** 0.8 (0.0)***

Richness Stat. 3.7 (0.5)*** 2.8* 2.3* 3.8* 1.2* 5.6 (0.3)*** 4.6 (0.4)***

SWDI Index 2 (0.1)*** 2.1* 1.9* 2* 0.2* 2.9 (0.1)*** 2.4 (0.1)***

AMBI Index 2.7 (0.1)*** 3.5* 3.1* 4.1* 5.9* 1.8 (0.1)*** 2 (0.2)***

M-AMBI Index 0.6 (0.0)*** 0.5* 0.5* 0.6* 0.1* 0.8 (0.0)*** 0.7 (0.0)***

BQI Index 6.8 (0.5)*** 4.3* 4.7* 4.8* 3.1* 9.4 (0.3)*** 7.6 (0.3)***


62

Figure A4.1 Mean (± SE) ash-free dry weight (AFDW), infauna abundance, taxa richness, and

Capitella sp. densities recorded for Forsyth Bay (FOR) salmon farm annual monitoring since 2001. Densities of capitellid polychaetes of 1,000 individuals per m² (= 13 per 0.013 m² core) are typically considered high (ANZECC 2000 guidelines). Data for 2018 are shown in red; no infauna data are available for the 50 m and 150 m stations as only indicator monitoring was carried out (the same applies in 2014 and 2017).


63

Appendix 5. Historical comparison of metals.

Figure A5.1 Average concentrations of total recoverable copper and zinc in sediments beneath NZ King Salmon’s four low-flow operational farms and two reference

stations (PS = Pelorus Sound, QC = Queen Charlotte). Bars represent averages (± SE). Note; the 2015 metals results are not directly comparable to other years due to the methodological differences in 2015 (only < 250 µm grain size fraction analysed).


64

Appendix 6. Full results for the Waihinau Bay (WAI) salmon farm.

Table A6.1 Detailed Enrichment Stage (ES) calculations for each station at the Waihinau Bay (WAI) salmon farm, October 2018. For details about how these values were calculated see MPI (2015). Asterisks indicate cases where best professional judgement (BPJ; Keeley et al. 2012) was required. n/c indicates cases where ES values were assigned at a higher level (i.e. at the macrofauna level).


65

Table A6.1 (cont.).


66

Table A6.2 Summary of the average (± SE) sediment physical and chemical properties, macrofauna variables and calculated indices for the Waihinau Bay (WAI) salmon farm, October 2018. Number of asterisks indicate the number of samples used to derive the score (i.e. '*' is n = 1).

Units Pen 1 Pen 2 180 m PS-Ctl-1 PS-Ctl-3

Depth m 24 26 28 28 36

Sed

imen

ts

AFDW % 12.6 (4.7)*** 10.6 (1.3)*** 5.4 (0.1)*** 5.4 (0.1)*** 5.5 (0.1)***

Redox EhNHE, mV -128.7 (13.1)*** -105 (7.5)*** 91.3 (19.9)*** 172 (34.6)*** 178 (30.7)***

Sulphides µM 4917.8 (1073.3)*** 8808.6 (3977.6)*** 395.8 (102.8)*** 70 (0.0)*** 85.4 (15.4)***

Bacterial mat - Yes, patchy Yes, patchy No No No

Out-gassing - No No No No No

Odour - Strong Moderate None None None

Mac

rofa

un

a s

tati

sti

cs

Abundance No./core 3323 (1993.3)*** 2664 (450.3)*** 129.3 (32.6)*** 100.3 (8.4)*** 70.7 (12.7)***

No. taxa No./core 8.3 (1.9)*** 8 (0.6)*** 25.7 (2.8)*** 25.7 (2.6)*** 20.7 (2)***

Evenness Stat. 0.4 (0.1)*** 0.5 (0.0)*** 0.8 (0.0)*** 0.8 (0.0)*** 0.8 (0.0)***

Richness Stat. 1.1 (0.3)*** 0.9 (0.1)*** 5.1 (0.3)*** 5.4 (0.6)*** 4.6 (0.4)***

SWDI Index 0.9 (0.1)*** 1 (0.1)*** 2.7 (0.1)*** 2.5 (0.2)*** 2.4 (0.1)***

AMBI Index 5 (0.2)*** 5.2 (0.1)*** 1.9 (0.2)*** 1.7 (0.0)*** 2 (0.2)***

M-AMBI Index 0.2 (0.0)*** 0.2 (0.0)*** 0.8 (0.0)*** 0.8 (0.1)*** 0.7 (0.0)***

BQI Index 2.6 (0.3)*** 2.6 (0.1)*** 8.3 (0.2)*** 10.5 (0.5)*** 7.6 (0.3)***


67


Capitella sp. densities recorded for Waihinau Bay (WAI) salmon farm annual monitoring since 2006. Densities of capitellid polychaetes of 1,000 individuals per m² (= 13 per 0.013 m² core) are typically considered high (ANZECC 2000 guidelines). Data for 2018 are shown in red.


68

Appendix 7. Full results for the Otanerau Bay (OTA) salmon farm. Table A7.1 Detailed Enrichment Stage (ES) calculations for each station at the Otanerau Bay (OTA) salmon farm, October 2018. For details about how these

values were calculated, see MPI (2015). Asterisks indicate cases where best professional judgement (BPJ; Keeley et al. 2012) was used. n/c indicates cases where ES values were assigned at a higher level (i.e. at the macrofauna level).


69

Table A7.1 (cont.).


70

Table A7.2 Average (± SE) sediment physical and chemical properties, macrofauna variables and calculated indices for the Otanerau Bay (OTA) salmon farm stations, October 2018. Number of asterisks indicate the number of samples used to derive the score (i.e. '*' is n = 1).

Station Units Pen 1 Pen 2 50 m 150 m QC-Ctl-1 QC-Ctl-2

Depth m 36 36 38 38 43 34

Sed

imen

ts

AFDW % 9.3 (1.7)*** 10.6 (0.4)*** 8.2 (0.2)*** 6.5 (0.1)*** 7.3 (0.1)*** 5.8 (0.2)***

Redox EhNHE, mV 12 (14.4)*** -23.7 (15.3)*** -62.3 (3.4)*** 141.7 (18.7)*** 189.3 (26.9)*** 162.3 (38.4)***

Sulphides µM 7012.8 (5033.7)*** 1795.1 (381.9)*** 1035.9 (158.8)*** 153.7 (84.7)*** 74.7 (5.7)*** 183.6 (82.9)***

Bacterial mat - Yes, Minor Yes, Minor No No No No

Out-gassing - Yes Yes No No No No

Odour - Mild Moderate None None None None

Mac

rofa

un

a s

tati

sti

cs

Abundance No./core 420.3 (174.4)*** 881.7 (430.5)*** 42 (4)*** 36.7 (8.2)*** 19 (4.6)*** 55.3 (2.4)***

No. taxa No./core 5 (1.5)*** 8.7 (1.2)*** 14 (2.1)*** 15.3 (1.2)*** 10.3 (1.7)*** 24.3 (2.3)***

Evenness Stat. 0.3 (0.1)*** 0.3 (0.0)*** 0.8 (0.0)*** 0.9 (0.1)*** 0.9 (0.0)*** 0.9 (0.0)***

Richness Stat. 0.7 (0.2)*** 1.2 (0.1)*** 3.5 (0.6)*** 4 (0.3)*** 3.2 (0.5)*** 5.8 (0.6)***

SWDI Index 0.4 (0.1)*** 0.6 (0.1)*** 2.2 (0.2)*** 2.4 (0.1)*** 2.1 (0.2)*** 2.9 (0.1)***

AMBI Index 5.8 (0.1)*** 5.8 (0.0)*** 3.3 (0.3)*** 1.3 (0.1)*** 1.6 (0.3)*** 1.9 (0.2)***

M-AMBI Index 0.1 (0.0)*** 0.2 (0.0)*** 0.5 (0.1)*** 0.7 (0.0)*** 0.6 (0.1)*** 0.8 (0.1)***

BQI Index 2.2 (0.3)*** 2.9 (0.1)*** 4.9 (0.7)*** 7.2 (1.1)*** 6.2 (0.9)*** 7.8 (0.6)***


71


Capitella sp. densities recorded for Otanerau Bay (OTA) salmon farm annual monitoring since 2001. Densities of capitellid polychaetes of 1,000 individuals per m² (= 13 per 0.013 m² core) are typically considered high (ANZECC 2000 guidelines). Data for 2018 are shown in red.


72

Appendix 8. Full results for the Ruakaka Bay (RUA) salmon farm. Table A8.1 Detailed Enrichment Stage (ES) calculations for each station at the Ruakaka Bay (RUA) salmon farm, October 2018. For details about how these

values were calculated, see MPI (2015). Asterisks indicate cases where best professional judgement (BPJ; Keeley et al. 2012) was used. n/c indicates cases where ES values were assigned at a higher level (i.e. at the macrofauna level).


73

Table A8.1 (cont.).


74

Table A8.2 Average (± SE) sediment physical and chemical properties, macrofauna variables and calculated indices for the Ruakaka Bay (RUA) salmon farm stations, October 2018. Number of asterisks indicate the number of samples used to derive the score (i.e. '*' is n = 1).

Station Units Pen 1 Pen 2 50 m 150 m QC-Ctl-3 QC-Ctl-4

Depth m 36 34 35 36 34 37

Sed

imen

ts

AFDW % 6.2 (1.5)*** 13 (2.1)*** 4.6 (0.1)*** 5.1 (0.2)*** 5.9 (0.1)*** 6.8 (0.2)***

Redox EhNHE, mV 124 (13.8)*** 7.3 (20.3)*** -24.7 (31.3)*** 98 (41.8)*** 124.3 (26.3)*** 104.3 (16)***

Sulphides µM 1288.1 (124.1)*** 1716.9 (186.2)*** 1460.3 (101.8)*** 604.3 (222.6)*** 228.8 (30)*** 69 (0.0)***

Bacterial mat - Yes, Minor Yes, Minor No No No No

Out-gassing - No No No No No No

Odour - Moderate Moderate None None None None

Mac

rofa

un

a s

tati

sti

cs

Abundance No./core 2600.3 (753.1)*** 2642.3 (522.3)*** 107.3 (66.6)*** 154 (79.5)*** 23.7 (3.5)*** 13 (2.9)***

No. taxa No./core 22.7 (2.9)*** 11 (2.5)*** 20.7 (7.5)*** 19.3 (6.4)*** 14.7 (1.5)*** 7.3 (2)***

Evenness Stat. 0.2 (0.0)*** 0.1 (0.0)*** 0.8 (0.0)*** 0.6 (0.1)*** 1 (0.0)*** 0.8 (0.0)***

Richness Stat. 2.8 (0.3)*** 1.3 (0.4)*** 4.4 (1)*** 3.8 (1)*** 4.3 (0.3)*** 2.4 (0.6)***

SWDI Index 0.7 (0.1)*** 0.3 (0.1)*** 2.3 (0.4)*** 1.6 (0.3)*** 2.6 (0.1)*** 1.6 (0.3)***

AMBI Index 5.5 (0.1)*** 5.9 (0.0)*** 2.7 (0.1)*** 3.1 (0.7)*** 1.2 (0.1)*** 1.3 (0.1)***

M-AMBI Index 0.4 (0.0)*** 0.2 (0.0)*** 0.7 (0.1)*** 0.6 (0.1)*** 0.7 (0.0)*** 0.5 (0.1)***

BQI Index 5.9 (0.5)*** 3.2 (0.3)*** 6 (0.9)*** 5.1 (1.1)*** 7.5 (0.6)*** 5.8 (1)***


75


Capitella sp. densities recorded for Ruakaka Bay (RUA) salmon farm annual monitoring since 2002. Densities of capitellid polychaetes of 1,000 individuals per m² (= 13 per 0.013 m² core) are typically considered high (ANZECC 2000 guidelines). Data for 2018 are shown in red.

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