39 REVIEW OF THE TASMANIAN ABALONE COUNCIL REPORT ON RISKS TO THE ABALONE FISHERY FROM FURTHER EXPANSION OF THE SALMONID INDUSTRY

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REVIEW OF THE TASMANIAN ABALONE COUNCIL REPORT ON RISKS TO THE
ABALONE FISHERY FROM FURTHER EXPANSION OF THE SALMONID
INDUSTRY
Technical Report · July 2015
DOI: 10.13140/RG.2.1.3815.7526

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REVIEW OF THE TASMANIAN ABALONE
COUNCIL REPORT ON RISKS TO THE ABALONE
FISHERY FROM FURTHER EXPANSION OF THE
SALMONID INDUSTRY

COLIN BUXTON

Colin Buxton & Associates

July 2015


Title

Author

REVIEW OF THE TASMANIAN ABALONE COUNCIL REPORT ON RISKS
TO THE ABALONE FISHERY FROM FURTHER EXPANSION OF THE
SALMONID INDUSTRY
Colin Buxton

Disclaimer
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errors or omissions. The author does not accept any form of liability, be it
contractual, tortious, or otherwise, for the contents of this document or for any
consequences arising from its use or any reliance placed upon it by any third
party. The information, opinions and advice contained in this document may not
relate, or be relevant, to a reader’s particular circumstance.
Copyright
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no part of this report may be reproduced by any process, electronic or otherwise,
without the specific written permission of the copyright owner. Information may
not be stored electronically in any form whatsoever without such permission.
 Colin Buxton & Associates.
Enquires should be directed to:

Prof Colin Buxton
Colin Buxton & Associates
27 Wandella Ave, Taroona 7053


ii


Executive Summary
On 3 December 2014 the Department of Primary Industries, Parks, Water and Environment
(DPIPWE), with the endorsement of the Minister for Primary Industries and Water
commissioned a review of a report by the Tasmanian Abalone Council Ltd (TAC) entitled:
Risks to the Tasmanian Abalone Fishery from further expansion of the Salmonid Industry
(TAC 2014).
After consultation with Tassal Group Ltd (Tassal), Huon Aquaculture Group Ltd (Huon
Aquaculture) and the TAC, the Terms of Reference (TOR) determined for the review were:
1. Against current scientific knowledge, assess and report on the veracity of the
assertions listed in the TAC Ltd report that relate to the potential impacts of salmonid
farming on the abalone sector in Tasmania.
2. Review the statutory monitoring requirements implemented for soluble and solid
waste from salmonid farming and report on its adequacy for assessing impacts of
salmonid farming in relation to the detection of impacts on rocky reef habitats.
3. Assess the status and productivity of fishing blocks 14b, 14c and 15 in SE Tasmania
and report on possible salmon farming impacts on abalone productivity.
4. Review the planned salmon industry amendments and expansion and report on the
potential risks to abalone and rock lobster fisheries, including harmful algal blooms
and disease transmission.
5. Assess the potential impacts of sediment from salmon farming on the abalone biology
and ecology.
In the preparation of this review the consultant interviewed the key stakeholders: TAC,

Tassal, Huon Aquaculture and researchers from the Institute for Marine and Antarctic Studies
at the University of Tasmania. The Tasmanian Rock Lobster Fisherman’s Association was
also consulted who indicated that they had resolved their concerns over the proposed
amendments with the salmon industry.
The structure of the review includes a section on each of the Terms of Reference.
The major findings are summarised as follows:
1. An analysis of changes to the marine farming zones and lease areas for each of the
recently approved and proposed marine farming development plan amendments
shows that, while there has been an overall increase in zone area (597.67ha), the
changes to the lease areas, i.e. where the farming occurs, have been relatively small
(105.57ha). The net effect has been an increase in leasable area for salmon marine
farming of 19.94ha, which is 1.86% of the total lease area (1073ha). The data do not
support the argument that there has been a significant expansion of salmon farming
operations in SE Tasmania as an outcome of the marine farming development plan
amendments in question.

1


2. An extensive literature exists on the near field impacts of salmon farming on the
marine environment in Tasmania. Research shows that while salmon farming may
have significant near field impacts below the cages, there is a gradient of impacts such
that effects beyond 35m from the lease boundary are minor. While the impact on reefs
is less well understood, the recent review of the Broadscale Environmental
Monitoring Program (BEMP) found no evidence of any major broadscale impacts of
salmon farming at present in the Huon / D’Entrecasteaux Channel region. This
suggests that MFDP amendments to salmon farming activities in the Channel will not
pose an unacceptable risk to the key abalone fishing areas to the south of this region.
3. Salmon farming has the ability to alter the environment, but the research and
monitoring conducted to date demonstrates that changes arising from the impacts of

solid wastes attributable to salmon farming are localised in relation to impact on
sediments below cages. Since the onset of salmon farming parts of the Huon and
D’Entrecasteaux system have changed from being oligotrophic (low nutrient) to
mesotrophic (moderate nutrient). However, within the limits of the imposed Total
Permissible Dissolved Nitrogen Output (TPDNO), these changes do not pose a
significant or unacceptable broadscale risk to the environment.
4. The impacts of salmon farming on exposed oceanic environments such as Storm Bay
are likely to be similar to those in sheltered waters elsewhere in SE Tasmania, with
one major difference that the impacts are likely to be dispersed more widely and
diluted more quickly. The current lack of understanding of the impact of salmonid
farming in open ocean exposed sites has been recognised and there are a number of
studies underway to improve our knowledge in this area. However, there are no data
to support the argument that future expansion should feature cages located four or
more nautical miles from inshore reef habitat.
5. DPIPWE uses an adaptive management approach to both fisheries and marine
farming, but this is clearly sector by sector. Given the concerns expressed by the
abalone sector, an opportunity exists for greater engagement. Such an approach to
adaptive management in the D’Entrecasteaux would seem appropriate and would
build on the planning provisions of the Marine Farming Planning Act 1995 which
enable the concerns and aspirations of competing interests to be identified, considered
and responded to in the statutory marine farming planning processes.
6. Evidence for a direct cause and effect relationship between loss of abalone
productivity and salmon farming is not clearly apparent from catch and effort data.
This analysis points to depletion in the fishery itself to be the most likely cause for a
loss of productivity in the Southeast and the Eastern zones in general. However, a
combination of factors, including salmon farming, may have a localised effect in
some places, especially where salmon farming occurs over an area of reef that is
currently or was historically suitable abalone habitat. Port Esperance is likely such an
example.
2

7. While abalone reef is found in proximity to salmon farms throughout the Channel,
and while some areas may have produced significant yields historically, most of these
areas are now minor to the fishery. The key fishing areas for abalone are at least
11kms from the nearest lease at Lippies Point and thus well outside of the detectable
impacts of salmon farming.
8. Recent amendments to MFDPs do not constitute a major expansion of marine salmon
farming in the Huon and D’Entrecasteaux regions and the industry operates within
prescribed TPDNO limits determined to ensure that there are no unacceptable
broadscale impacts to the environment from salmonid farming. Elevated nutrients
levels are mostly in the northern parts of the system while the main abalone fishing
areas occur in the south and are located well beyond the detectable limits of impact
from salmon farming. These factors suggest that recent and proposed amendments to
marine farming development plans will not increase the risk of Harmful Algal Blooms
(HABs) to the abalone industry.
9. While there is the potential for disease transfer from escaped fish, the low level of disease
in farmed Tasmanian salmonids combined with relatively low loss rates from recent years
means that such a risk is very low. More generally, pathogens do not cross phylum
barriers hence the risk of disease transmission between salmon and other species such
as abalone and rock lobster would appear to be low.
10. Inshore marine environments receive inputs from a number of sources including
upstream activities that include agriculture and forestry, marine farming, industrial
outfall and waste treatment plants, as well as numerous natural sedimentation
processes. No evidence supports the claim that the ‘milky dust’ on macroalgae in
parts of the system is derived from salmon farming. Until such time that the sediments
can be properly sampled and analysed it is premature to attribute the source, or a
portion of the source, to any sector.

3

TABLE of CONTENTS

1. Against current scientific knowledge, assess and report on the veracity of the assertions
listed in the TAC report that relate to the potential impacts of salmonid farming on the
abalone sector in Tasmania. ....................................................................................................... 6
1.1 Do the proposed amendments in the lower D’Entrecasteaux Channel represent a
significant expansion of salmon farming operations in the area? .......................................... 6
1.2

Does salmon farming impact the water quality and substrate characteristics? ........... 7

1.3 What localised amenity impacts from salmon farming may impact the abalone
fishery? ................................................................................................................................... 9
1.4 How well are near field and far field impacts of salmon farming on the environment
understood? .......................................................................................................................... 10
1.5

What is known about the impacts of salmon farming in “oceanic” environments? . 10

1.6 Does the current environmental monitoring of near-farm and/or broadscale effects
represent a conflict of interest or lack of independence? ..................................................... 11
1.7

What is the risk of eutrophication of the system arising from salmon farming? ...... 11

1.8 What is the origin of the fine sediment observed on macroalgae in the Port
Esperance area ..................................................................................................................... 12
1.9 How is the Precautionary Principle used in the making of decisions relating

environmentally sustainable development in an adaptive management context? ............... 12
2. Review the statutory monitoring requirements implemented for soluble and solid waste
from the salmonid farming and report on its adequacy for assessing impacts of salmonid
farming in relation to the detection of impacts on rocky reef habitats. ................................... 15
2.1

Introduction ............................................................................................................... 15

2.2 Monitoring and reporting requirements – D’Entrecasteaux Channel, Huon River and
Port Esperance MFDP areas. ............................................................................................... 16
2.3

Evaluating the BEMP ................................................................................................ 17

2.4

Detecting impacts on rocky reefs .............................................................................. 20

3. Assess the status and productivity of fishing blocks 14B, 14C and 15 in SE Tasmania
and report on possible salmon farming impacts on abalone productivity. .............................. 23
4. Review the planned salmon industry amendments and expansion and report on the
potential risks to abalone and rock lobster fisheries, including harmful algal blooms and
disease transmission. ................................................................................................................ 34
4.1

Introduction ............................................................................................................... 34

4.2

Planned expansion of the salmon industry ................................................................ 34

4.3

Recent amendments to salmon farming in the Huon and D’Entrecasteaux Channel 35
4


4.4

Risks to abalone and other reef fisheries ................................................................... 38

5. Assess the potential impacts of sediment from salmon farming on the abalone biology
and ecology. ............................................................................................................................. 43
5.1

Organic sedimentation from salmon farming............................................................ 43

5.2

Organic and inorganic sedimentation in the marine environment ............................ 44

5.3

In situ net cleaning as a potential source of sediments ............................................. 45

6.

References ........................................................................................................................ 47

7.

Appendices ....................................................................................................................... 51
Appendix 1 - Environmental monitoring and reporting requirements of salmonid licence
holders in the D’Entrecasteaux Channel and Huon River and Port Esperance marine
farming development plan areas ...................................................................................... 51
Appendix 2 – Schedule 3 BEMP ..................................................................................... 56
Appendix 3: Current and planned research aimed at improving the understanding of the
broadscale, far-field and reef impacts of salmonid farming in Tasmania........................ 72

5


1. Against current scientific knowledge, assess and report on the veracity
of the assertions listed in the TAC report that relate to the potential
impacts of salmonid farming on the abalone sector in Tasmania.
Concerns relating to the potential impacts of salmon farming on the abalone wild fishing
sector in Tasmania have been made in a report entitled “Risks to the Tasmanian Abalone
Fishery from further expansion of the Salmonid Industry” (TAC 2014). The major assertions
listed in the report are examined through a series of questions:
-

Do the proposed amendments in the lower D’Entrecasteaux Channel represent a
significant expansion of salmon farming operations in the area?
Does salmon farming impact the water quality and substrate characteristics?
What localised amenity impacts from salmon farming may impact the abalone
fishery?
How well are near field and far field impacts of salmon farming on the environment
understood?
What is known about the impacts of salmon farming in “oceanic” environments?
Does the current environmental monitoring of near-farm and/or broadscale effects

represent a conflict of interest or lack of independence?
What is the risk of eutrophication of the system arising from salmon farming?
What is the origin of the fine sediment observed on macroalgae in the Port Esperance
area?
How is the Precautionary Principle used in the making of decisions relating
environmentally sustainable development in an adaptive management context?

A summarised answer to each of these key questions is presented below, while more detailed
consideration and referencing is found in subsequent sections that relate to Terms of
Reference 2-5.

1.1 Do the proposed amendments in the lower D’Entrecasteaux Channel represent a
significant expansion of salmon farming operations in the area?
Page 7 of the TAC Report outlines plans for the expansion of farming operations in the
southern part D’Entrecasteaux Channel (Tassal) and north Bruny Is. (Huon Aquaculture).
This question relates to the suggestion that salmon farming has expanded significantly in the
D’Entrecasteaux Channel (Channel) and that this represents a risk to the abalone fishery,
particularly in the southern part of the Channel which is adjacent to the key abalone fishing
area of Block 13. These concerns are addressed in more detail under Section 2 and Section 4.
An analysis of changes to the marine farming zones and lease areas for each of the recently
approved and proposed amendments shows that, while there has been an overall increase in
zone area (597.67ha), the changes to the lease areas, i.e. where the farming occurs, have been
relatively small (105.57ha) (see Table 4.2). In two cases, Flathead Bay and Lippies Point,
6


increases in the Channel have been offset by similar decreases in lease area in the Huon River
and Channel respectively. The net effect of all of these amendments has been an increase in
leasable area for salmon marine farming of 19.94ha, which is 1.86% of the total lease area
(1073ha) in the Huon River and Port Esperance Marine Farming Development Plan (MFDP)

and D’Entrecasteaux Channel MFDP areas.
The increase in lease area in the Channel are of primary concern to TAC, however, as a
percentage of the total lease area in the D’Entrecasteaux Channel MFDP this still only
represents a 3.11% increase.
The data do not support the argument that there has been a significant expansion of salmon
farming operations in the area.

1.2 Does salmon farming impact the water quality and substrate characteristics?
The TAC Report states (pg 7): “It is a widely acknowledged fact that salmon farming (as
previously and currently practised in Tasmania) has a detrimental effect on water quality and
substrate characteristics in close proximity to farming operations”.
Page 8 of the TAC Report states: “The principal ongoing risk to the abalone industry is
degradation of the marine environment upon which the resource and the industry depend”
and “Salmon farming is one anthropogenic activity that poses a risk to the Tasmanian wild
abalone fishery. This risk increases when salmon farming is conducted in close proximity to
the benthic reef communities that abalone inhabit”.
This question addressed the potential environmental impact of salmon farming in the
D’Entrecasteaux Channel and the risk that this might pose to reef communities and hence the
abalone fishery. It is discussed in more detail below under Section 2 and Section 4.
Since 2009 nitrogen released into the marine environment by fish farms in the Huon River
and Port Esperance MFDP and the D’Entrecasteaux Channel MFDP has been regulated via
limits or caps on total permissible dissolved nitrogen output (TPDNO). The cap for the
D’Entrecasteaux Channel MFDP area is 1,190.42 1 tonnes in any 12 month period. Ross &
Macleod (2013) show that in the D’Entrecasteaux Channel MFDP area inputs have increased
from 709 tonnes in 2009 to 849 tonnes in 2011. Despite this increase, the data show that
farms were operating well within the TPDNO limits set for the MFDP area (see Table 4.1).
An extensive literature exists on the near field impacts of salmon farming on the marine
environment in Tasmania. These studies show that nutrient enrichment from uneaten food
and faecal material may have a considerable impact on the benthos immediately below the
cage and within lease boundaries, but that there is a gradient of impact that diminishes with

1

This figure was increased from 1140.67 tonnes in March 2015

7


distance from the cage and that impacts of salmon farming were minor at distances of 35m
from the lease boundary (see Edgar et al. 2005 and references therein).
Early studies of the broadscale impacts of effluent from marine farming on rocky reef
communities found no apparent patterns of change in macroalgal community composition
over a10 year time period between 1992 and 2002 (Crawford et al. 2006). However, more
recent work on the macroalgal composition in the Huon and D’Entrecasteaux Channel (Oh
2009) has shown that macroalgal composition at sites located 100m from farms was clearly
different from reference sites 5km away in both exposed and sheltered areas. While
differences were apparent at the sites situated 400m metres away from fish farms, these were
not significantly different from sites 5km away.
Analogous to the results elsewhere in the world, Oh (2009) showed that the effect of
salmonid marine fish farms in SE Tasmania was characterised by increases in the cover of
epiphytes and total opportunistic algae (which included opportunistic green algae,
filamentous algae and algal turf). In particular, opportunistic green alga of the genera
Chaetomorpha, Ulva and Cladophora (the main constituent of filamentous green algae in this
region) were collectively responsive to the proximity of fish farms. Despite limitations in
study design (including the re-analysis of reef survey data not specifically designed to test the
effects of salmon farming), her findings appear to support anecdotal observations of changes
in the Channel.
However, Oh (2009) found that there was no apparent decline of canopy algae close to fish
farms (as has been reported for other cases of eutrophication), and, although average diversity
and species richness were lowest at sites 100m from fish farms, they were not significantly

different from reference sites. This suggested that while variations in the detectable effects of
fish farms could be anticipated at scales of several hundreds of metres from fish farms, they
rarely reached distances of several kilometres away from farming areas.
While abalone reef is found in close proximity to some salmon farms throughout the
Channel, and while some of these areas may have produced significant yields historically,
most of these areas are now insignificant to the fishery (see Section 3). The key fishing areas
for abalone in Block 13 are at least 11kms from the nearest salmon marine farming leases at
Browns Point and Lippies Point and thus well outside of the near field impacts of salmon
farming.
Research shows that while salmon farming may have significant near field impacts below the
cages, there is a gradient of impacts such that effects beyond 35m from the lease boundary
are minor (Edgar et al. 2005). While the impact on reefs is less well understood, the recent
review of the Broadscale Environmental Monitoring Program (BEMP) found no evidence of
any major broadscale impacts of salmon farming at present in the Huon / D’Entrecasteaux
Channel region (Ross & Macleod 2013).
This suggests that proposed MFDP amendments to salmon farming activities the Channel
will not pose an unacceptable risk to the key abalone fishing areas to the south of this.
8


Modelling (Wild-Allen et al. 2005; Volkman et al. 2009) has demonstrated that the Huon and
D’Entrecasteaux region are hydrodynamically well connected (to the Southern Ocean in the
south and Storm Bay in the north), with a residual circulation from south to north which
flushes the whole region (a full exchange of water) over about two and a half weeks. This
disperses local nutrient sources widely, however, there has been a regional elevation of
nutrient and phytoplankton biomass to a modest degree. As a consequence, Volkman et al.
(2009) conclude that since the onset of salmon farming the system has changed from being
oligotrophic (low nutrient) to mid band mesotrophic (moderate nutrient).
Ross and Macleod (2013) concluded that despite the changes in ammonium and oxygen
concentration in the Huon River there was no evidence of a change in water column

productivity. There was, however, some evidence to support a change in phytoplankton
composition in the system.
It is clear that salmon farming has the ability to alter the environment, but the research and
monitoring conducted to date demonstrates that these changes are localised in relation to
impact on sediments below cages and that, within the limits of the TPDNO, nutrients from
salmon farming do not pose a significant or unacceptable broadscale risk to the ecosystem in
the Huon River and Port Esperance and D’Entrecasteaux Channel MFDP areas.

1.3 What localised amenity impacts from salmon farming may impact the abalone
fishery?
The TAC Report states (pg 7): “Salmon farming generates localised amenity impacts such as
noise and visual pollution, boating & navigational hazards and reduces waterway area
available for general unrestricted use”.
The local amenity impacts from salmon farming are discussed in detail in each of the
Environmental Impact Statements relating to proposed amendments to MFPDs in the Huon
River and D’Entrecasteaux Channel.
Apart from simply noting the concerns expressed by TAC in relation to these issues, it is hard
to understand how abalone fisheries are impacted by reduction in waterway area, visual
pollution and noise. Major abalone fishing grounds are located for the most part well away
from salmon leases.
Sharks are an ever present OH&S risk to commercial diving operations, however, the
salmonid industry reports very limited shark interactions with any of their dive teams
working on a full time basis around the State. There is no data to suggest sharks are attracted
to salmon farming operations and no data to suggest that interactions are increasing.
Navigational hazards around marine farming lease areas exist but are explicitly managed and
mitigated by Marine and Safety Tasmania regulations.

9

1.4 How well are near field and far field impacts of salmon farming on the environment
understood?
The TAC Report states (pg 7): “The salmonid industry and State and Federal Governments
have invested significant resources into understanding the near-farm environmental effects of
salmonid production. The broadscale and long-term environmental impacts of salmonid
farming on the marine environment are less well understood”.
This question relates to possible near field and far field risks of salmon farming to abalone
fisheries and is discussed in more detail under Section 2 and Section 4.
The near-farm (i.e. within the marine farming zone) environmental effects of salmon farming
in Tasmania have indeed been well studied, but there is also a considerable body of research
into the broadscale effects of salmon farming on the environment in SE Tasmania. What is
less well understood are what is termed far field effects, i.e. those that occur beyond the
boundary of the farm zone, and particularly the impacts on reefs. This deficiency has been
recognised and there are a number of studies underway to improve our knowledge in this
area. These are listed under Section 4.
Understanding the potential long term environmental impacts is the aim of the ongoing
BEMP. The recent review of the BEMP data found that to date there is no evidence of any
significant or unacceptable broadscale impacts of salmon farming at present in the Huon /
D’Entrecasteaux Channel region.

1.5 What is known about the impacts of salmon farming in “oceanic” environments?
The TAC Report states (pg 7): “There is a general lack of research regarding the
environmental impacts of salmonid farming on inshore Tasmanian oceanic benthic flora and
fauna communities”.
Page 22 of the TAC Report recommends: “….future expansion….should feature the use of
offshore cage systems that are located four (4) nautical miles away from inshore oceanic reef
habitat”.
Salmon farming in SE Tasmania MFDP areas has to date occurred in the relatively sheltered
waters of the Huon River estuary, Port Esperance and the D’Entrecasteaux Channel,
however, Huon Aquaculture has recently commenced farming on the open ocean exposed

north eastern shore of Bruny Island outside of these areas.
The impacts of this farming on this environment are likely to be similar to those elsewhere,
with one major difference being that the area is more exposed and thus the waste products of
farming (uneaten feed and faecal material) as well as products of in situ net cleaning are
likely to be dispersed more widely.
The current lack of understanding of the impact of salmonid farming in open ocean exposed
sites has been recognised and there are a number of studies underway to improve our
10


knowledge in this area (see Appendix 3). While research will need to be undertaken to better
understand these effects, the dilution effect of more open water farming is likely to mitigate
these risks to the marine environment. However, there are no data to support the argument
that future expansion should feature cages located four or more nautical miles from inshore
reef habitat.

1.6 Does the current environmental monitoring of near-farm and/or broadscale effects
represent a conflict of interest or lack of independence?
Pg 7 of the TAC Report lists the environmental monitoring of broadscale effects undertaken
by the salmon industry as “…raising concerns regarding conflict of interest/lack of
independence”.
License holders must comply with environmental management standards in carrying out
operations on the marine farming lease area. Companies and/or consultants undertake this
work according to specifications prescribed by DPIPWE and the data is reviewed by
DPIPWE.
The BEMP sample collection for the years 2009-2012 was undertaken by Aquenal, an
independent environmental consultancy employed by the industry peak body, the Tasmanian
Salmonid Growers Association (TSGA) and authorised by the Secretary DPIPWE to
undertake such work.
Aquenal Pty Ltd is an environmental consulting company based in Hobart with offices in

Perth that provides services in the areas of biological and environmental assessment of
marine, estuarine and coastal habitats.
Consultants operate under strict requirements set by DPIPWE for the collection of monitoring
data and may be audited by DPIPWE

1.7 What is the risk of eutrophication of the system arising from salmon farming?
The TAC Report states (pg 10): “Artificial salmon feed residues and salmon excreta in high
concentrations can lead to eutrophication within the water column – i.e. nutrient overload
which in turn can lead to hypoxia (oxygen depletion) and phytoplankton blooms”.
This question is examined in more detail in Section 4.
Studies show that phytoplankton biomass in the Channel is higher in the warmer summer
months with peaks in spring and autumn. The timing and intensity of blooms is highly
variable as are their appearance at different sites within the system. Fish farm discharges
impact the biogeochemistry of the Huon River and D’Entrecasteaux Channel by increasing
the supply of nitrogen and phosphorous available for phytoplankton growth particularly in
summer when nutrients are limiting. Biogeochemical modelling has demonstrated that the
11


region is hydrodynamically well connected with a residual circulation from south to north
which flushes the whole region over about two and a half weeks. This disperses local nutrient
sources widely and results in regional elevation of nutrient and phytoplankton biomass to a
modest degree (Wild Allen et al. 2005). Since the onset of salmon farming parts of the
system have changed from being oligotrophic (low nutrient) to mesotrophic (moderate
nutrient). Volkman et al. (2009) showed that within the nutrient limits imposed by the
TPDNO the proportion of the system classified as mesotrophic would increase from
approximately 10% (no salmon farming) to around 54%. This was insufficient to produce
eutrophication and therefore considered an acceptable risk of marine salmonid farming to the
environment.

1.8 What is the origin of the fine sediment observed on macroalgae in the Port
Esperance area
The TAC report presents an underwater video that claims to provide imagery of the impact of
salmonid farming on the marine environment (pg 13) in the form of a ‘milky dust’ on
macroalgae.
The area in question, Port Esperance, is a sheltered bay that is a receiving environment from
several sources including:
-

Riverine inputs including upstream activities that include agriculture and forestry
Salmon and mussel farming
The outfall of a fish processing factory
The Dover Wastewater Treatment Plant
Natural sedimentation via the faecal products of zooplankton and phytoplankton.

Salmon farming is a source of sediments derived from excess feed, faecal material and more
recently through in situ net cleaning – these topics are covered in more detail in Section 5.
Contrary to statements in the TAC report (pg 10), mussels and other bivalves may also be a
significant source of sedimentation through the production of psuedofaeces, which arise when
there are either excess or unwanted material filtered from the environment.
No evidence is provided to support the TAC claim and until such time that the sediments can
be properly sampled and analysed it is premature to attribute the source, or a portion of the
source, to the salmon industry.

1.9 How is the Precautionary Principle used in the making of decisions relating
environmentally sustainable development in an adaptive management context?
The TAC Report calls for the adoption of the Precautionary Principle in Government decision
making (pg 4). It quotes the Wikipedia definition of the principle as: “The precautionary
principle or precautionary approach states that if an action or policy has a suspected risk of
12

causing harm to the public or to the environment, in the absence of scientific consensus that
the action or policy is not harmful, the burden of proof that it is not harmful falls on those
taking an action”. .
The Precautionary Principle rose to prominence following its inclusion in the Rio Declaration
on Environmental Development (Principle 15) which describes the precautionary approach
and its use in the context of environmental conservation as, “[w]here there are threats of
serious or irreversible damage, lack of full scientific certainty shall not be used as a reason
for postponing cost-effective measures to prevent environmental degradation”.
This description substantially differs from the Wikipedia definition used by the TAC in that it
is explicit that the risk must be one of serious or irreversible damage. Recent reviews of the
precautionary principle confirm that identification of a threat, and determination that that
threat is significant, should be key prerequisite steps in accepting the application of the
Principle (Kearney et al. 2012).
In the application of the precautionary principle, public and private decisions should be
guided by:
-

Careful evaluation to avoid, wherever practicable, serious or irreversible damage to
the environment; and
An assessment of the risk-weighted consequences of various options.

A major characteristic of the precautionary principle is that it specifies that measures must be
taken if there are threats of serious or irreversible environmental damage and these measures
should be relaxed only if research demonstrates that they are not needed.
It is not consistent with the Principle to allow scientific uncertainty to negate the necessity to
assess whether any particular action or event is a threat. Nor is it appropriate to assume that a
threat, once identified, is sufficiently significant to uncritically trigger precautionary action.
The need for precaution should not be used to provoke or justify an assumption that

something is a threat without sufficient evidence. UNESCO 2005 states, “Some form of
scientific analysis is mandatory; a mere fantasy or crude speculation is not enough to trigger
the Precautionary Principle”
The National Strategy for Ecologically Sustainable Development (ESD) has three core
objectives: to enhance individual and community well-being and welfare by following a path
of economic development that safeguards the welfare of future generations; to provide for
equity within and between generations; and to protect biological diversity and maintain
ecological processes and life support systems.
The strategy is implemented under the guidance of a number of ecological and development
principles. The ecological principles are:
-

Decision making processes should effectively integrate both long and short-term
economic, environmental, social and equity considerations,
13


-

-

Where there are threats of serious or irreversible environmental damage, lack of full
scientific certainty should not be used as a reason for postponing measures to prevent
environmental degradation, and
The global dimension of environmental impacts of actions and policies should be
recognised and considered.

The developmental principles are:
-

The need to develop a strong, growing and diversified economy which can enhance
the capacity for environmental protection should be recognised,
The need to maintain and enhance international competitiveness in an
environmentally sound manner should be recognised, and
Cost effective and flexible policy instruments should be adopted, such as improved
valuation, pricing, and incentive mechanisms, and decisions and actions should
provide for broad community involvement on issues which affect them.

The strategy emphasises that a balanced approach is required for ESD and these guiding
principles and core objectives need to be considered as a package. No objective or principle
should predominate over the others.
Management judgements have to be based on the available scientific evidence of the risk
being undertaken, and the levels of short and long-term impacts that are acceptable in the
socio-economic as well as ecological areas.
Adaptive management is an approach for simultaneously managing and learning about
natural resources (Williams 2011), and is an approach used by DPIPWE in the management
of abalone and other wild fisheries as well as salmon farming. A key step in the adaptive
management process is to engage appropriate stakeholders and to ensure their involvement in
the process. This has been the motivation behind projects such as Your Marine Values (Ogier
& Macleod 2013) and underpins the Fisheries Advisory Committee (FAC) process which
includes stakeholders in the co-management of all Tasmanian fisheries resources. Clearly, to
date, adaptive management has proceeded sector by sector and it is probably appropriate, in
the context of concerns expressed by the abalone industry over the potential impacts of
salmon farming on the environment, to seek ways of integrating this response. To achieve
this each sector would have to articulate common objectives that accounted for the
aspirations of each other. Such an approach to adaptive management in the D’Entrecasteaux
would seem appropriate and would build on the planning provisions of the Marine Farming
Planning Act 1995 which enable the concerns and aspirations of competing interests to be
identified, considered and responded to in the review of draft MFDP’s and draft amendments
to MFDP’s.

14


2. Review the statutory monitoring requirements implemented for soluble
and solid waste from the salmonid farming and report on its adequacy
for assessing impacts of salmonid farming in relation to the detection of
impacts on rocky reef habitats.
2.1 Introduction
Open cage salmon aquaculture is a significant point source of nutrients to the marine
environment. Volkman et al. (2009) estimate that approximately 30% of the nutrients added
through fish feed are removed from the marine ecosystem as fish at salmon harvest, but the
remainder are released to the environment as metabolic wastes and uneaten feed. Of this an
estimated 80% of the total nutrient losses from fish farming are dissolved and in a form that
is readily available to macroalgae, microalgae and plants such as seaweeds.
To date most of the research and monitoring of the nutrient impacts of salmon farming on the
environment has focussed on understanding and measuring impacts on benthic soft sediment
habitats below and adjacent to the cages (Crawford et al. 2002; Macleod et al. 2002;
MacLeod et al. 2004; Edgar et al. 2005), and understanding the broadscale impacts of
nutrient enrichment on primary production, predominantly phytoplankton (CSIRO 2000,
Volkman et al. 2009).
Studies have shown that nutrient enrichment from uneaten food and faecal material may have
a considerable impact on the benthos immediately below the cage (Macleod 2004b and
references therein), but that there is a gradient of impact that diminishes with distance from
the cage (Edgar et al. 2005 and refs therein). Benthic impacts of salmon farming were minor
at distances of 35m from the lease boundary (Edgar et al. 2005) although local conditions
greatly influenced the level of impact at the level of individual farm leases (Macleod et al.
2004b).
Building on the Huon Estuary Study (CSIRO 2000), Volkman et al. (2009) showed that
eutrophication will become a problem if the assimilation capacity of a salmon-growing area

for nutrients is exceeded. This could lead to phytoplankton blooms, which may include
harmful species that produce harmful algal blooms (HABs) (see commentary on HABs in
Section 4), or be manifested as increased production of benthic microalgae, macroalgae or
epiphytic algae. The released nutrients may change ambient nitrogen/phosphorus (N/P) ratios
and can alter the ratio of key phytoplankton species (e.g. from diatoms to dinoflagellates).
Effects of increased nutrients may also be seen at higher trophic levels, by altering the
abundance and species composition of zooplankton, which in turn can affect fish
communities.
Rocky reefs are a dynamic and productive ecosystem, usually dominated by canopy-forming
perennial macroalgae, performing an important ecosystem function in terms of carbon
storage, nutrient cycling and the provision of food and habitat for a diverse range of fish and
invertebrates (Worm & Lotze 2006). In Tasmania rocky reefs are essential habitat for
important commercial species such as abalone and rock lobster.
15


Coastal nutrient enrichment due to human activities has been shown to result in a decline of
perennial species and the growth and dominance of annual filamentous and sheet like algae
on temperate rocky reefs (Kraufvelin et al. and references therein). Boris and Lotze (2006)
showed that grazers were important in structuring rocky reefs as they were able to keep
bloom forming species in check, however, grazing could not override the effects of increased
eutrophication.
2.2 Monitoring and reporting requirements – D’Entrecasteaux Channel, Huon River
and Port Esperance MFDP areas.
Marine farming operations in Tasmania are managed under the provisions of Marine
Farming Planning Act 1995 (MFPA) and the Living Marine Resources Management Act
1995 (LMRMA).
The MFPA provides for the preparation of marine farming development plans (MFDP) which
contain management controls to manage and mitigate negative effects of marine farming
operations. Management controls include provisions relating to environmental monitoring

and management of marine farming operations.
Management controls contained within the Huon River and Port Esperance and
D’Entrecasteaux Channel marine farming development plans cover a range of issues
including:
-

Levels of unacceptable effects
Nitrogen outputs
Carrying capacity
Monitoring requirements
Chemical usage and reporting
Waste
Disease
Visual effects
Access and marking
Odour
Noise
Marine farming equipment
Predator control

The LMRMA requires marine farming leaseholders to hold a marine farming license to farm
fish (under the LMRMA fish include a range of species). Marine farming licenses provide
the authorization to the holder to engage in the activity of marine farming and contain
specific provisions in relation to environmental monitoring and management of marine
farming operations. In many cases license conditions contain specific requirements to
expand and support the provisions of MFPP management controls.
A summary of the environmental monitoring and reporting requirements of salmonid licence
holders in the D’Entrecasteaux Channel and Huon River and Port Esperance MFDP areas is
16

provided in Appendix 1. The information presented is derived from salmonid marine farming
schedules, the statutory instruments used to mandate monitoring and reporting requirements.

2.3 Evaluating the BEMP
The Broadscale Environmental Monitoring Program (BEMP) was initiated in 2009 to assess
water and sediment quality and is a regulatory compliance requirement, in accordance with
salmonid marine farming licence conditions. The aim of the BEMP is to provide data to
enable a comprehensive assessment of the ecological condition in the D’Entrecasteaux
Channel and the Huon River estuary.
The BEMP was initiated following an extended period of scientific research funded through
the Fisheries Research and Development Corporation (FRDC) and the Finfish Aquaculture
Cooperative Research Centre (Aquafin CRC) between 1996 and 2009. It was based primarily
on recommendations of research undertaken by Thompson et al. (2008) and Volkman et al.
(2009), which looked at the effects of salmonid aquaculture on the environment.
The key elements of the BEMP are:
-

to assess water and sediment quality and benthic infaunal condition at a specified
number of sites throughout the region (see Figure 2.1),
that all licence holders in the MFPD must participate in the monitoring,
that monitoring is undertaken by an independent and appropriately qualified
consultant,
that all data and reports are lodged with the DPIPWE and
that assessment and review of the resultant data be undertaken at regular intervals
with a view to ensuring that both the water column and sedimentary environment
remain in a satisfactory condition and that the monitoring program is relevant and
effective.

The BEMP sample collection is undertaken by Aquenal, an independent environmental

consultancy employed by the industry peak body, the Tasmanian Salmonid Growers
Association (TSGA).

17


Figure 2.1 Map showing the location of monitoring sites in the D’Entrecasteaux Channel and Huon Estuary.
Sediment assessment sites are shown as red circles (B1-B15) and water quality monitoring sites as green squares
(M1-M15). The control site at Recherche Bay is located in the bottom left corner of the map (B15/M15) (after
Ross & Macleod 2013).

The most recent assessment of the BEMP data was undertaken by the Institute for Marine and
Antarctic Studies (IMAS) at the University of Tasmania and is summarised in a report by
Ross and Macleod (2013). The aim of this report was to provide an evaluation of the
observed monitoring data and to assess the outputs against ecosystem performance measures.
Specifically this included:
-

-

Analysis and interpretation of the environmental data collected as part of the BEMP
assessments between 2009 and 2012 in the context of other available information
(including catchment input data and other historical environmental data available
from the Huon Estuary, D'Entrecasteaux Channel and elsewhere).
Provision of advice to the DPIPWE regarding the relationship between the monitoring
data, relevant CSIRO model outputs and recommended trigger levels.
18


-

Identification of any significant gaps in the monitoring data and making
recommendations regarding data collection and analysis.

Key findings of the BEMP review may be summarised as follows (Ross & Macleod 2013):
a) Water Quality
- Catchment inflows, fish farms and oceanic inputs are the major sources of nutrients,
particularly nitrogen, but they vary in the form of nitrogen they input to the system.
o Catchment inputs are predominately organic nitrogen, fish farms are the most
significant source of ammonium, and oceanic inputs are the major source of
nitrate and nitrite.
o Waste Water Treatment Plants (WWTP) and industrial inputs are relatively
small at the whole of system level, yet their loads are predominately in the
form of ammonia which may be significant with respect to the local receiving
environment.
o Nitrogen inputs from fish farms are based on feed data. Inputs of dissolved
nitrogen in the Huon River and Port Esperance MFDP Area have remained
relatively stable at ~ 1000 tonnes p.a. across the calendar years (i.e. 2009,
2010 & 2011) that incorporated this BEMP monitoring period. In the
D’Entrecasteaux Channel MFDP area, however, inputs have increased from
709 tonnes in 2009 to 849 tonnes in 2011. Seasonally, feed inputs are at their
lowest in late summer before increasing through winter to a maximum in
spring each year. This trend is more defined in the Huon than the Channel
where autumn seems to be the period whee feed inputs are lowest.
o Ammonium is one of the most labile forms of N and is readily taken up by
plankton and algae.
o There is a considerable exchange of D’Entrecasteaux Channel and Huon
Estuary waters with oceanic waters across the northern and southern
boundaries of the system, predominantly in winter. Oceanic inputs are the
major source of nitrate and nitrite and represent approximately 60% of the

nitrogen load to the system.
- Biological uptake of nutrients occurs predominantly in spring and autumn which is
reflected in peak phytoplankton growth. Blooms typically occur between spring and
autumn.
- Ammonium concentrations are higher in the Huon Estuary and the northern parts of
the Channel which is consistent with the understanding of regional circulation that
would accumulate nutrient inputs in these areas.
- A comparison of the BEMP data collected from 2009-12 with historical data sets from
the Huon Estuary (HES: 1996-1998 and Aquafin CRC: 2002-2005) and the
D’Entrecasteaux Study (Aquafin CRC: 2002-2005) suggested that, despite
considerable spatial and temporal variability in data, there was evidence of decadal
system wide changes that were consistent with the increased inputs of organic matter
and nutrients. They included an increase in ammonium concentrations in bottom and
19


-

surface waters and a decrease in bottom water oxygen concentrations in the Huon.
Although variability in the region’s hydrodynamics may have contributed to these
changes it seemed likely that they were due to a combination of increased organic
load to sediments and subsequent remineralisation as well as increased inputs via fish
excretion. A lack of comparable data in the Channel pre BEMP obfuscated a
meaningful assessment in the Channel.
Despite the changes in ammonium and oxygen concentration in the Huon there was
no evidence of a change in water column productivity. There was however, some
evidence to support a change in phytoplankton composition in the system.

b) Sediments
- The BEMP is a substantial baseline dataset of sediment condition for all of the

broadscale monitoring sites.
- Infaunal community relationships and comparisons with previous studies provide no
evidence of any major broadscale impacts of salmon farming beyond the lease area
boundary in the Huon Estuary and D’Entrecasteaux Channel regions.
- Spatial patterns were very similar to those observed in previous studies (Macleod &
Forbes 2004a,b; Edgar et al. 2005; Macleod et al. 2008).
- There was no evidence in the infaunal community composition of any significant
organic enrichment or change in the community or function.

2.4 Detecting impacts on rocky reefs
Research and monitoring of the impacts of salmon farming on the environment has been
focussed on near field impacts close to the cages and broadscale impacts on other, closely
connected, aspects of the ecosystem. Few studies have assessed the impacts on rocky reefs.
This approach has been justified because salmon farms, with few exceptions, are usually
located over soft sediments (Table 2.3) with more recent amendments deliberately avoiding
proximity to reefs (DPIPWE 2015).
In recent decades anthropogenic eutrophication has been shown to change the structure and
diversity of marine benthic communities (Pearson & Rosenberg 1978, Lotze & Schramm
2000, Kraufvelin et al. 2010) with opportunistic fast-growing species frequently occurring in
eutrophic coastal waters (Cederwall & Elmgren 1990). These macroalgal blooms are
generally explained by increased nutrient loads which selectively favour filamentous and
foliose macroalgae.
Several studies have found significant differences in the macrobenthic assemblages near fish
farms and there has been a growing awareness of the potential far-field impacts of salmon
farming on the system (see Oh 2009 and references therein). A study of the macroalgal
composition in the Huon River and D’Entrecasteaux Channel showed that macroalgal
composition at sites located 100m from farms were different from reference sites 5000m
away in both exposed and sheltered areas. Sites situated 400m away from fish farms were,
however, not significantly different from sites 5000m away (Oh 2009).
20

Table 2.3 – Size and distance from the shore of marine farming lease areas in Port Esperance and
D’Entrecasteaux Channel (* denotes recent amendments or proposed amendments to MFDPs)
LEASE
Electrona MF76
Gunpowder Jetty MF76
Tinderbox MF90
Sheppards Point MF94
Simmonds Point MF154
Roberts Point MF142
Sykes Cove MF73
Apollo Bay MF74
Meads Creek MF77
Soldiers Point MF110
Simpsons Point MF115
Simpsons Point MF182
Satellite Island MF34
*Zuidpool Rock MF141
Great Taylors Bay MF185 & MF203
*Butlers Point MF109
*Lippies Point MF78 -Existing
*Lippies Point MF78 - Proposed
Stringers Cove MF209
Stringers Cove MF244
*Browns Point MF262

FROM
COASTLINE
(meters)

Touches
150
185
50
240
58
14
53
Touches
790
10
234
Touches
2600
1320
470
1200
1460
80
125
1130

SIZE
(hectares)
8 combined
19
20
7
30
3

10
38
15
9
15
30
154
75 + 75
28
38
77
25
5
38

FROM
REEF
(meters)
Over reef
100
210
35
220
48
Over reef
13
Over reef
120
Over reef
155

Over reef
1100
1280
450
430
410
30
Over reef
410

Analogous to the results of other studies on macroalgal composition and nutrient enrichment
from other anthropogenic sources, Oh (2009) found the effect of fish farms was characterised
by increases in the cover of epiphytes and total opportunistic algae (which included
opportunistic green algae, filamentous algae and algal turf). In particular, opportunistic green
alga of the genera Chaetomorpha, Ulva and Cladophora (the main constituent of filamentous
green algae in this region) were collectively responsive to the proximity of fish farms.
Oh (2009) also found that there was no apparent decline of canopy algae close to fish farms,
as has been reported for other cases of eutrophication. The study suggested that while
variations in the detectable effects of fish farms could be anticipated at scales of hundreds of
metres, they rarely reached distances of several kilometres away from farming areas.
However, Crawford et al. (2006) undertook an analysis of a 10 year dataset from two small
marine protected areas (Ninepin Point at the mouth of the Huon estuary and Tinderbox near
North West Bay) for changes in abundance of the seven most abundant macroalgal species.
This study was aimed at assessing whether broadscale impacts of effluent from marine
farming activities could be detected at rocky reef communities and found no apparent
patterns of change in macroalgal community composition over the 10 year time period.
From this it would appear that although nutrient impacts have been detected some distance
from salmon farms the nutrient load has been insufficient to result in significant changes to
macroalgal communities on rocky reef habitats.
The relative lack of information on the far-field impact of salmon farming on temperate reefs

in the D’Entrecasteaux Channel and perceived inadequacies in the BEMP have been
21


highlighted in several submissions to the Marine Farming Planning Review Panel (the Panel)
in relation to the most recent amendments to the Huon River and Port Esperance and the
D’Entrecasteaux Channel MFPDs. The Panel in making its decision on these amendments
has recognised this deficiency stating for example:
“The Panel noted concerns that the BEMP did not adequately address impacts of marine
farming on reef fauna and macroalgae, but also noted the current research being undertaken
by IMAS to examine possible relationships”
“The Panel concluded that the BEMP provided an adequate monitoring framework for the
adaptive management of marine farming in the MFDP in terms of local (benthic sediments
within the farm zone) and broadscale nutrient inputs. The Panel was, however, concerned
that the amendments to the Huon and Channel plans could result in alterations to the
distribution of nutrient inputs to the system which could have impacts which would probably
not be identified by the current monitoring regime” (MFPRP Zuidpool Decision Report).
In response to these concerns, several research projects are underway or planned to further
improve the understanding of the impact of salmon farming, especially on temperate reefs
(Dr Catriona Macleod IMAS pers. comm.). They are listed below and summarised in
Appendix 3:
FRDC 2011/042: Atlantic Salmon Aquaculture Subprogram: clarifying the relationship
between salmon farm nutrient loads and changes in macroalgal community structure/
distribution.
FRDC 2012/024: INFORMD Stage 2: Risk-based tools supporting consultation,
planning and adaptive management for aquaculture and other multiple-uses of the
coastal waters of southern Tasmania.
Seafood CRC Project 2011/735 - An evaluation of the options for the expansion of
salmonid aquaculture in Tasmanian waters. Phase III: Information Assessment/
Decision Support Framework (Pilot Study-Storm Bay).

FRDC 2015/024 Managing ecosystem interactions across differing environments:
building flexibility and risk assurance into environmental management strategies.
FRDC CC035 Reassessment of intertidal macroalgal communities near to and distant
from salmon farms and an evaluation of using drones to survey macroalgal distribution
FRDC TRF (submitted) Understanding broadscale impacts of salmonid farming on
rocky reef communities

22