Draft Rock Lobster Fishery
Harvest Strategy
An Information Paper
December 2015
Contents
Introduction ___________________________________________________________________________ 1
What is a harvest strategy? ______________________________________________________________ 2
2009 Rock Lobster Harvest Strategy
Why has the harvest strategy been changed?
2
2
Proposed Rock Lobster Fishery harvest strategy ___________________________________________ 3
What is the aim of the new harvest strategy?
What are the main components of the harvest strategy?
What is standardised CPUE and why is it being used?
Getting the harvest rate right
Rationale for choosing these harvest rates
Other harvest rate options considered
3
3
3
3
4
5
How does the strategy work? ____________________________________________________________ 5
Harvest rate and limit reference points
Pre-recruit index
Egg production
TACC Caps
One-jump rule
TACC Tables
5
6
6
6
6
7
How will TACCs be set? _________________________________________________________________ 8
Decision Rules
8
Conclusion ___________________________________________________________________________ 9
References ___________________________________________________________________________ 9
Appendix 1 __________________________________________________________________________ 10
What are the components of a harvest strategy?
10
Appendix 2 __________________________________________________________________________ 11
Key Fishery Statistics – Western Zone
Key Fishery Statistics – Eastern Zone
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Introduction
This paper provides an overview of the proposed harvest strategy for the Victorian Rock Lobster
Fishery. It also explains how the harvest strategy was developed and why certain parameters were
chosen.
The proposed strategy is based on commercial catch rate and has been designed to be more
transparent and less reliant on model outputs. The previous management plan, put in place in 2009,
used a harvest strategy with an explicit rebuilding target and timeline. Rebuilding the stock required
substantial reductions in total allowable commercial catches but resulted in improvements in catch
rate and stock levels.
Despite these improvements, the catch rates in Victoria remain the lowest of the rock lobster fisheries
in Australia and New Zealand. A common goal for the Government and Industry is to ensure that the
fishery has the capacity to continue rebuilding and to future-proof itself should any unfavourable
conditions (e.g. environmental changes, low recruitment, falling egg production) arise in the future.
The proposed harvest strategy takes a precautionary approach and uses egg production, standardised
catch rate and numbers of juvenile lobsters in the population as determinants for setting the annual
total allowable commercial catches.
The strategy aims to be precautionary enough to ensure that the conditions for export approval
required by the Environment Protection and Biodiversity Conservation Act 199 and that the
sustainability requirements of the Status of Key Australian Fish Stocks are met.
The proposed harvest strategy is part of the new draft Rock Lobster Fishery Management Plan and was
developed by Fisheries Victoria with the assistance of an independently chaired Steering Committee.
The Steering Committee was comprised of representatives from the commercial and recreational
fishing, conservation, and government sectors and included an independent scientific advisor.
The Management Plan and harvest strategy have been released for public consultation as per the
requirements in the Fisheries Act 1995.
The Management Plan and the harvest strategy will be used to set the TACCs in the Rock Lobster
Fishery for the season commencing 1 July 2016 and will be in effect for a minimum of five years.
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What is a harvest strategy?
Put simply, harvest strategies set catch limits for commercial fisheries and provide a clear framework
for how those catch limits will be set. Harvest strategies use a systematic approach to assess the
status of a fishery and a include set of rules that are used to determine what the catch limits will be.
Because these rules are set out in advance, fishers and fishery managers know what actions will be
taken in response to the conditions in the fishery.
2009 Rock Lobster Harvest Strategy
The previous harvest strategy was designed at a time when the fishery was experiencing some of the
lowest catch rates in its history and below average recruitment levels. The aim of the harvest strategy
was therefore to rebuild the rock lobsters stocks in both commercial zones of the fishery.
To ensure that rebuilding took place and was kept on track, a target of 40% of the stock level in 1951
by the year 2020 was used.
Since the introduction of that harvest strategy in 2009, the declining trend in catch rate in both zones
has been reversed. Catch rates in the Western Zone increased from 0.37kg/pot lift to 0.56kg/pot lift in
2013/14 and from 0.38kg.pot lift to 0.52kg/pot lift in the Eastern Zone. This improvement in catch rate
reflects the improvement in the stock in the fishery (the available biomass) (Figure 1).
To achieve these increases in catch rate and stock, it has been necessary to reduce annual total
allowable commercial catches.
Eastern Zone
Western Zone
2009 Harvest
Strategy
Available biomass (tonnes)
Available biomass (tonnes)
1800
1600
1400
1200
1000
800
600
400
200
0
600
500
400
2009 Harvest
Strategy
300
200
100
0
Figure 1: Abundance of legally-sized rock lobsters in each zone. Improvements are evident from 2009 onwards.
Why has the harvest strategy been changed?
While the 2009 harvest strategy was successful in rebuilding the rock lobster stock, it was heavily
reliant on a stock assessment model to estimate future conditions in the fishery and to set the TACC
each year. Because of this reliance, it was difficult for fishers and fishery managers to predict and plan
for future TACCs until the modelling had been completed.
There was therefore a need for a harvest strategy that was simple, straightforward and which allowed
fishers to be able to better predict upcoming TACCs using fishery data available throughout the season.
For that reason, the new harvest strategy uses catch rate as a basis to determine the TACC.
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Proposed Rock Lobster Fishery harvest strategy
What is the aim of the new harvest strategy?
The harvest strategy aims to achieve two main operational objectives, both of which link to the
overarching objectives in the Management Plan. These are:
1. Continue to rebuild the rock lobster population by setting appropriately conservative TACCs on
an annual basis.
2. Maintain standardised catch rates above 0.40 kg/pot lift.
What are the main components of the harvest strategy?
1. The harvest strategy is a catch rate-based strategy that uses standardised catch per unit effort
(CPUE).
2. TACCs are predetermined for a particular catch rate and are based on harvesting a set
proportion of the stock (the harvest rate).
3. The harvest rate is constant unless the catch rate falls below 0.4kg/pot lift (the upper limit
reference point, refer to Appendix 1), when it is incrementally reduced. The fishery will be
closed if the catch rate falls to 0.25kg/pot lift (the lower limit reference point) or less.
4. TACCs are set using the standardised CPUE in that year’s stock assessment and a pre-recruit
index in combination with a set of decision rules that determine whether the annual TACC is
increased or decreased in the following season.
What is standardised CPUE and why is it being used?
Catch rate, or CPUE, is representative of rock lobster abundance.
Catch rates are, however, influenced by factors that are not related to abundance including changes in
fishing areas locations, fishing experience and changes in fishing gear that make fishers more efficient.
To get the most accurate estimate of the abundance in a zone, data from the catch and effort logbooks
is, therefore, standardised for differences among regions, depth ranges, fishing seasons, months,
fishers and vessels.
Standardising catch rates allows fishery managers to accurately compare catch rates between years
and to see changes in abundance.
It is acknowledged that there continues to be concern from Industry regarding the factors being
standardised and the method of standardisation. These will be evaluated in 2016.
Getting the harvest rate right
The foundation of this harvest strategy is the harvest rate (also referred to as exploitation rate), which
is the proportion of the available stock that can be caught.
Setting the right harvest rate is a balance between sustainability of the resource and maximising the
economic value of the industry.
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Setting the harvest rate too low may rebuild the stock faster but it could result in lower TACCs in the
short-term and a challenging economic situation for fishers. A harvest rate that is too high can result
in minimal to no increase in biomass over time and therefore no improvement to the stock status,
catch rates, economic efficiency or profitability of the industry.
The proposed harvest strategy does not include a rebuilding target so it is important that the harvest
rate is conservative enough to ensure that the stock rebuilds, that catch rates improve, that profits are
maximised and that the objectives of the harvest strategy and management plan can be met.
The harvest rates in the proposed harvest strategy are 30% for the Western Zone and 15% for the
Eastern Zone. These values mean that, in the case of the Western Zone for example, 30% of the total
stock above legal size can be caught and 15% in the Eastern Zone.
Rationale for choosing these harvest rates
Between 2011/12 and 2013/14, the harvest rates in the Western Zone have been between 38% and
39% of the available stock biomass. Over the same timeframe, harvest rates in the Eastern Zone have
been 21%, 16% and 18% per season (refer to Figures 5 and 8 in Appendix 2).
The harvest rates used for this harvest strategy are therefore a slight reduction on the recent averages
in each zone.
While there have been improvements in stock levels, there are concerns about the capacity of the
fishery to continue rebuilding and to future-proof itself should any unfavourable conditions (such as
environmental changes) arise in the future:







Levels of egg production are low across the whole of south-eastern Australia.
The numbers of pre-recruits and undersize lobsters continue to be below average in Victoria.
Biomass levels in the fishery are about 50% of 1978 levels (1978 = catch and effort logbooks
introduced).
Levels of CPUE are still reasonably low at around 0.55kg/pot lift (unstandardised) in each zone
and have not improved for the last three years.
The CPUEs in Victoria continue to be some of the lowest values in rock lobster fisheries in the
country and overseas.
Although stock has been rebuilding, the numbers of lobsters that have been growing through
the fishery have come from higher levels of recruitment and the indications are that these
trends will not continue.
High beach prices have kept the fishery profitable but profitability should come from increased
catch rates and a decreased effort to catch the quota.
A summary of a number of important fishery trends can be found in Appendix 2.
These trends emphasise that a precautionary approach is necessary and that the lower harvest rates
are the only way to ensure stocks will continue rebuild and that catch rates and industry profitability
improves.
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Other harvest rate options considered
A range of harvest rates were considered to make sure the most appropriate was chosen for each
zone. An examination of the likely future effects of the different options was also undertaken by
modelling the outputs going forward 15 years. For the Western Zone, harvest rates of 25%, 30%,
32.5% and 35% were considered and for the Eastern Zone, 15%, 17.5% and 20%.
Noting that modelling future outcomes is not exact, in both zones, the most conservative harvest rates
gave the most immediate stock rebuilds, considerably higher levels of CPUE and much lower levels of
effort (number of pot lifts) to catch the TACCs. The levels of stock growth were also considerably
higher under these scenarios. Consideration was therefore given to the potential economic impact on
industry profitability through a potential reduction in TACC.
Conversely, under the 35% and 20% harvest rate scenarios for the Western and Eastern Zones,
respectively, the improvements to the biomass and the CPUE over the 15-year time frame were almost
negligible. Consideration was therefore needed regarding whether these scenarios supported the
objectives of the Fisheries Act and the Management Plan to rebuild the stock and make the industry
more profitable.
The most viable options that supported a strong rebuild in the stock as well as a reduction in effort
without creating a significant burden on industry were the harvest rates of 30% and 15% for the
Western and Eastern Zones, respectively.
How does the strategy work?
Harvest rate and limit reference points
Under this harvest strategy, harvest rates remain constant as long as the standardised CPUE remains
above the upper limit reference point (Figure 2). This means that as the stock biomass grows, the
TACC will also increase (i.e. 30% of a 500 tonne stock biomass is 150 tonne and 30% of a 1000 tonne
stock is 300 tonnes).
When the standardised CPUE is above the limit reference point and improving, the TACCs can be
increased as long as certain conditions are met. These conditions are explained in the following
section.
The limit reference point acts like a safety measure. In the case of this harvest strategy, an upper and
a lower limit reference point have been established; both are CPUE-based. If the annual standardised
CPUE falls below the upper limit reference point, the harvest rate is decreased each year until the
CPUE is again above the upper limit.
If the standardised CPUE falls below lower limit reference point, the fishery will be closed to all fishing.
The upper limit reference point was determined based on the objective in the harvest strategy to stay
above a standardised CPUE of 0.40kg/pot lift.
The lower limit reference point, a standardised CPUE of 0.25kg/pot lift, was chosen based on the
lowest values experienced in the fishery.
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Upper limit reference point
Harvest rate decreases
Constant harvest rate
30%
15%
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0.45
0.4
0.35
0.325
0.3
0.275
0.25
0
0
Harvest rate
Lower limit reference point
Fishery closed
Standardised CPUE (kg/pot lift)
Figure 2. Theoretical construction of the proposed harvest strategy framework.
Pre-recruit index
The pre-recruit index (PRI) is an indicator of the likely future stock levels in the fishery and is used as a
threshold value in this harvest strategy. A threshold value sets a baseline with which to make
comparisons, i.e. whether the PRI is above or below the threshold value. The threshold values for the
PRI will be determined using the average number of undersize lobsters per pot lift from the fixed site
surveys over a particular length of time.
The threshold PRIs for each zone will be established during the first year of the harvest strategy. The
PRI for that year must be above the threshold level for a TACC increase in the zone to be considered.
Egg production
Egg production is an estimate of the spawning capacity of the stock. It is a crucial determinant of the
health of the stock and is used in this strategy as a primary indicator in the decision rules. A measure
of egg production has been set that is equivalent to 20% of the estimated egg production in 1951 (the
beginning of commercial fishing records). To be able to consider an increase in TACC, the egg
production must be above this threshold.
TACC Caps
An upper limit, or cap, on possible TACC levels has been included in this harvest strategy. The cap for
the Western Zone is 300 tonne and is 70 tonne for the Eastern Zone. This means that, over the life of
the harvest strategy, the TACCs cannot go above a certain level even if the standardised CPUE values
are continually increasing.
One-jump rule
To maintain the focus on rebuilding the rock lobster stocks, the TACCs can only be increased by one
level at any one time.
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TACC Tables
The levels of TACC are pre-set and based on the chosen harvest rate. The values of the TACCs and the
corresponding CPUE are in Tables 2 and 3.
These tables, in association with the decision rules (see next section) will be used to set the TACCs for
the fishery over the life of the Management Plan.
Table 2: CPUE bands and corresponding TACC
levels for the Western Zone
WESTERN ZONE TACC LEVELS
Table 3: CPUE bands and corresponding TACC
levels for the Eastern Zone
EASTERN ZONE TACC LEVELS
CPUE band
TACC Levels with 300t cap
CPUE band
TACC Levels with 70t cap
<0.25
0.25 - <0.275
0.275 - <0.3
0.3 - <0.325
0.325 - <0.35
0.35 - <0.375
0.375 - <0.4
0.4 - <0.45
0.45 - <0.5
0.5 - <0.55
0.55 - <0.6
0.6 - <0.65
0.65 - <0.7
0.7 - <0.75
0.75 - <0.8
0
18
39
64
92
123
158
202
226
250
274
298
300
300
300
<0.25
0.25 - <0.275
0.275 - <0.3
0.3 - <0.325
0.325 - <0.35
0.35 - <0.375
0.375 - <0.4
0.4 - <0.45
0.45 - <0.5
0.5 - <0.55
0.55 - <0.6
0.6 - <0.65
0.65 - <0.7
0.7 - <0.75
0.75 - <0.8
0
4
8
14
20
26
33
42
47
51
56
60
65
69
70
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How will TACCs be set?
The annual TACC is determined using a combination of the TACC tables (see previous section) and the
PRI and is set using decision rules. The decision rules used in the harvest strategy provide clear
guidance on the TACC-setting process by defining how estimates of standardised CPUE and PRI should
be interpreted and linking them to a set of rules for adjusting the TACC.
Decision Rules
1. Egg production. Modelled estimated egg production must be above the limit reference point
of 20% of the egg production in 1951 (E1951)with a 90% probability. If this decision rule is not
met, the TACC will be determined using the rock lobster fishery projection model to ensure
that the TACC returns the egg production to above the limit reference point within two years
with a 90% probability.
This decision rule must be satisfied before the CPUE-based harvest strategy can be used to set
the TACC.
2. TACC Determination. When Decision Rule #1 has been met, the TACC is set using the
standardised CPUE tables.
Using the standardised CPUE of the preceding season, the appropriate CPUE band is identified
and the corresponding TACC level is set according to the following conditions:
a. The TACC can be increased to the next level when:


the standardised CPUE is in a band higher than in the previous season; and
the PRI is at or above the trigger point of xx undersize per pot lift for the
Western Zone or xx undersize per pot lift for the Eastern Zone (Note: these
values will be determined over 2016/17 by the Rock Lobster Resource
Assessment Group).
The TACC can only be increased one level per year.
b. The TACC will remain at the same level when:
i. the standardised CPUE remains in the current band;
OR
ii. the standardised CPUE has increased to a higher band but the PRI is below the
trigger point.
c. The TACC will be decreased when:

the standardised CPUE has decreased into any lower band.
The TACC will be set at the level that corresponds to the standardised CPUE.
3. TACC Cap. A TACC cap of 300 tonnes in the Western Zone and 70 tonnes in the Eastern Zone
will be used over the life of the harvest strategy.
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Conclusion
The draft Rock Lobster Fishery Management Plan and harvest strategy have been released for public
comment.
Written submissions can be made by Friday, 4 March 2016 to:
The Rock Lobster Fishery Manager
2A Bellarine Highway
Queenscliff VIC 3226
or melissa.schubert@ecodev.vic.gov.au.
At the conclusion of the public consultation, comments received will be reviewed and any necessary
changes or amendments will be made. The Management Plan will then be published and the harvest
strategy used to set the TACCs in the Rock Lobster Fishery for the season commencing 1 July 2016.
Any written submissions received in relation to the consultation being conducted by Fisheries Victoria
will be published on the Department's website. In making a submission, unless the person making the
submission indicates to the contrary, they will be consenting to their submission, including their name
only, being published on the Department's website for 90 days from the conclusion of the consultative
process.
References
Sloane, S. R., Smith, A. D. M., Gardner, C., Crosthwaite, K., Triantafillos, L., Jefferies, B. and Kimber, N.
(2014). National Guidelines to Develop Fishery Harvest Strategies. FRDC Report – Project 2010/061.
Primary Industries and Regions, South Australia, Adelaide, March
Fletcher, W. J., Chesson, J., Fisher, M., Sainsbury, K., Hundloe, T.M.F., Smith, A.D.M., and Whitworth, B.
(2002). National ESD Reporting Framework for Australian Fisheries: The ‘How To’ Guide for Wild
Capture Fisheries. FRDC Project 2000/145, Canberra, Australia, 120p.
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Appendix 1
What are the components of a harvest strategy?
In practice, there are a number of components that make up a harvest strategy. Most commonly,
harvest strategies are written in combination with a fishery management plan. The fishery
management plan sets out high level strategic management objectives to guide the direction of the
fishery and these are translated into operational objectives in the harvest strategy. Operational
objectives need to be easily measured and linked to performance indicators, reference points and
decision rules. The operational objective, performance indicator and reference point form a package
and are the system used to measure the performance of the fishery (Sloan et al 2014, Fletcher et al
2002)
Management Plan
 High level strategic objectives
Harvest Strategy
 Operational objectives
Performance
Indicators




Reference
Points
Decision
Rules
Operational objectives are practical and measureable, and explicitly state what is intended by
the harvest strategy.
Performance indicators are quantities that can be measured and are used to track the fishery’s
performance against achieving an operational objective (Fletcher et al 2002).
Reference points are the ‘benchmarks’ for the performance indicators and are linked to setting
acceptable levels of biological impact on the fishery. There are three types of reference points:
target, limit and trigger. If, during the assessment of the fishery, a reference point is breached,
the pre-determined management action will result, consistent with established decision rules
(Sloan et al 2014).
o A target reference point represents a fishery indicator that is ideal or at which
management should aim. Often, target reference points are based on economic or
social outcomes (e.g. high catch rates, achieving maximum economic yield).
o A limit reference point sets the level at which that indicator for the fishery should not
go below. These reference points and associated indicators are usually connected to
biological sustainability of the fishery.
o A trigger reference point represents the point when a substantial change occurs. They
are often set at levels which, if reached, provide an alert that stock trends in the fishery
have deteriorated.
Decision rules are predetermined management responses that relate to the status of the
fishery as determined through the fishery assessments.
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Appendix 2
Key Fishery Statistics – Western Zone
Figure 3. Model estimated level of egg production through time in the WZ with a probability of 75%.
Figure 4. Nominal and standardised catch rates (kg/pot lift) in the WZ.
Figure 5. Relationship between abundance of legally-sized lobsters (available biomass) and exploitation rate
(catch/available biomass) in the WZ.
Key Fishery Statistics – Eastern Zone
Figure 6. Model estimated level of egg production through time in the EZ with a probability of 75%.
Figure 7. Nominal and standardised catch rates (kg/pot lift) in the EZ.
Figure 8. Relationship between abundance of legally-sized lobsters (available biomass) and exploitation rate
(catch/available biomass) in the EZ.
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vic.gov.au/fisheries