117

Development toward the New Management Scheme forSouthern Bluefin Tuna
Sachiko TSUJI
Fishery Information, Data and Statistics Unit (FIDI),
Food and Agriculture Organization of the United Nations (FAO)
Viale delle Terme di Caracalla, 00100 Rome, Italye-mail: sachiko.tsuji@fao.org

Abstract
Historically, management of the southern bluefin tuna had been a great dispute among relevant
parties. However, the situation is improving in recent years, mainly due to the introduction of the independent Advisory Panel to the scientific process of the Commission for the Conservation of Southern
Bluefin Tuna (CCSBT) and its agreement to adopt a management scheme based on the Management
Procedure, a set of pre-specified TAC adjustment rules evaluated with thorough simulations. Concepts
and the progress of developing Management Procedures under the CCSBT are introduced. Some of theadvantages of Management Procedure are: 1) avoids continuous and consistent struggle in selecting
appropriate management action by choosing pre-specified rule beforehand, and 2) chooses management
plan by examining effectiveness for multiple or even contradictory objectives with clear understandingon trade-off. Limitations in Management Procedures are: 1) underestimates the uncertainty intrinsic tostock assessment model in general, especially on absolute stock level and projections, and 2) only valid
within the uncertainty range that is examined.
Key words: adaptive management, CCSBT, decision rule, Management Procedure,Southern bluefin tuna (Thunnus maccoyii), stock assessment, trade-off

1. Introduction
The southern bluefin tuna, Thunnus maccoyii, is atemperate tuna species distributed in the southernhemisphere with high commercial value. This species
may have gained a reputation as the center of severe
conflicts among relevant parties regarding its management, especially through an international legal dispute
relating to the field experiment conducted in 1999 and2000 by Japan. The species was originally managed
through an informal management scheme establishedin 1983 among Australia, Japan and New Zealand.
This trilateral management scheme succeeded to implement substantial and sequential TAC (Total Allowable Catch) reductions during 1985 and 1989 and thepost-1989 TAC became about one third of the early
1980s’ level. The scheme was formalized as the
CCSBT (Convention for the Conservation of Southern
Bluefin Tuna) in 1994.
Around the same time, however, the discrepancies
in views among the parties on the stock status andhow to manage the stock became more distinct and the
CCSBT started having a difficulty in resolving management issues. This was also the time when the stock
Global Environmental Research9(2)/2005: 117-124
printed in Japan

started showing sign of recovery in young fish as a
combined result of substantial TAC reduction and several relatively high recruitments. Generally speaking,an absolute stock abundance and a recent trend of thestock are the two most difficult components to estimate accurately in stock assessment. However, those
are the key components controlling overall future
stock dynamics under a given catch scenario and information directly linking to management decisions. It
should be noted that it is even harder to assess andevaluate data and information obtained from stock
when the stock is at a turning point such as the beginning of a recovery. Thus, the scientists involved in the
CCSBT at that time eventually failed to resolve thedifference in views on stock status and could not deliver a unified recommendation for management as a
Scientific Committee. The managers fought bitterly,with one seeking an immediate TAC increase in a response to a sign of stock recovery and another doubting the credibility of the sign of stock recovery andinsisting to defer the TAC increase until the time thestock recovery would become a solid fact. Theysought different way to resolve the uncertainties instock assessment and this led to a legal dispute at the©2005 AIRIES118

S. TSUJI

end. For those who are interested in the dispute, an
overall description of the case is available at
http://www.rikkyo.ne.jp/~kanehara/article.htm and all
the legal documents for the provisional measures at
http://www.itlos.org/start2_en.html and for the arbitration at http://www.oceanlaw.net/cases/tuna2.htm.
The dispute ended with the denial of ITLOS (International Tribunal for the Law of the Sea) jurisdiction
by the Arbitral Tribunal, indicating that the ITLOS
should not and could not override disputes and decisions within the RFMO (Regional Fishery Management Organization) if other dispute settlement measures were agreed on beforehand among the RFMO
members. This meant that the CCSBT members had tosit down again and resolve the issues by themselves.
Gradually though, the members re-established goodcollaboration, even stronger than before the dispute,and took several measures to improve the impasse at
the scientific forum. Most effective among them was
the introduction of an independent Advisory Panel
who would act as arbitrators and could report directly
to the Commission when there were conflicts among
member scientists.
The first stock assessment after the dispute wasconducted in 2001 (CCSBT, 2001a). Although the
Scientific Committee delivered a report with unified
view mainly due to the efforts by the Advisory Paneland the general attitude of national scientists to accept
the wordings proposed by the Panel, this did not meanthat the wide diversion in views on the stock status
was somehow narrowed. Given a large uncertainties
around stock assessment, the Panel strongly urged the
CCSBT to move toward a new management scheme
called the Management Procedure, which was a set ofpre-determined TAC adjustment rules whose effects
and robustness were evaluated with thorough simulations beforehand. The CCSBT adopted that proposal.
The most well known and most intensively worked
example of the management procedures will be the‘Revised Management Procedure’ adopted by theInternational Whaling Commission, though they were
evaluated but not yet implemented. The scheme wasalso applied to various commercial stocks (e.g.,
Germont et al., 1999; Butterworth & Punt, 1999; Kellet al., 1999; Parma, 2002). Still, the concept was relatively new and the southern bluefin tuna will be thefirst case in which this idea is applied to a highly
migratory large pelagic species managed within aninternational setting, if successively implemented. We
are now in the final phase of developing the Management Procedure. I would like to take this opportunity
to briefly review the development process with someof my own insights.
The purpose here is to introduce the overall concept of management procedures with consideration on
their merits and demerits as well as the practical difficulties encountered during a development process.
Technical details of the model structures, assumptions,and mathematical specifications are not included
unless they are critical. Most of the description isbased on the reports of the CCSBT meetings that areavailable at http://www.ccsbt.org/docs/meeting_r.html.
The technical details discussed are usually available in
the attachments of the relevant reports.

2. Concept of Management Procedures
What are the ‘management procedures’? At the
CCSBT, the Management Procedure is defined as ‘a
set of rules that are agreed in advance, that dictate
how the Total Allowable Catch (TAC) for the fisherywill be adjusted as new data are collected’ (CCSBT,
2001a). Frequently, the term of ‘management
procedure’ also indicates the whole process including
pre-specified TAC adjustment rules and evaluation of
the performance of those rules through simulations.
Here, the term ‘management procedure’ is used toindicate the whole process and the pre-specified TAC
adjustment rules are referred to as ‘decision rules.’Figure 1 illustrates the three components required

Fig. 1 Overall scheme of Management Procedure concept (from the presentation by R. Hilborn).

Development toward the New Management Scheme for Southern Bluefin Tunain management procedure evaluation. This figure isborrowed from the slides that Ray Hilborn, one of the
Panel members, used to explain the concept ofManagement Procedure to managers and industries ata very early stage of development. It should be notedthat the terminology in this drawing is not exactly thesame as those developed within the CCSBT at a laterstage (see Annex 1).
First, it is necessary to develop a virtual world todescribe stock dynamics including the catch and data
provision processes. This virtual world will be used
to evaluate the performance of various decision rules.
To make the virtual world as similar as possible to thereality, the model should be adjusted using the available historical data. This process is called ‘conditioning’ and is illustrated as the top box named the ‘conditioning component.’ Conditioning is identical to stock
assessment in a sense, except that the purpose here is
not to find the most credible value but to identify awhole plausible range of uncertainties. Thus the outcome from the conditioning components is an assemblage of estimation results spread throughout a reasonably plausible range.
In the second box named the ‘projection component,’ various decision rules, TAC adjustment rules,
are applied to the virtual world controlled with the‘operating model.’ Although the projection part ofoperating model carries the same parameters andmodel structures that are determined in the ‘conditioning component’ in principle, further uncertainties areadded to incorporate unknown features of future projections such as recruitment fluctuations and observation errors. Types of errors to be considered have beenreviewed by Butterworth & Punt (1999).
This illustration shows a case using an assessment
model to provide a TAC for the next term. Decisionrules, however, can be either model-based or empirically based. In the case of empirical decision rules,
information obtained from the ‘sampling model’
directly goes into the ‘management model’ to determine the TAC for the next time step.
Through simulation in the ‘projection component,’
information on how well the rules work in managing
the stock is collected. This information is called ‘performance indicators’ or ‘performance statistics’ asshown in the bottom box. In fisheries management,
there are generally three objectives: i) maximizing
catches, ii) minimizing the risk of stock collapse, andiii) maximizing the stability of industry. Performancestatistics are set separately for each objective. Apparently i) and ii) are contradictory and cannot be attained simultaneously. The capability to examine theperformance of various decision rules with multiple
axes of objectives is one of the strong benefits of management procedures. Quick and simple examples of
performance statistics include an average catch for acertain period for i), a proportion of stock below acertain level for ii) and an average level of TAC
changes in an absolute term for iii).

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This whole process is repeated to make sure thatthe plausible uncertainty space is reasonably covered.
Then, in theory, it should be possible to select such arule that works reasonably well wherever the real
stock status is, as long as it is within the examined
range of uncertainty. It should be noted that this process is consistent with the precautionary approach tofisheries management determined by the FAO (Foodand Agriculture Organization of the United Nations)in 1996.

3. Progress under the CCSBTThis section briefly describes the development
process of management procedures at the CCSBT.
The CCSBT agreed to develop the Management
Procedure as the highest priority among its scientifictasks in 2001 (CCSBT, 2001b). Although the model
specification was to be determined through discussion
among national scientists and the Advisory Panel, the
CCSBT decided to hire an independent technical consultant for developing code for all necessary programs.
The national scientists’ role would be to explore arange of candidate decision rules using their own
judgment on the relative priority of different management objectives and own preference for the nature andcomplexity of the rules. This decision was made to be
sure to avoid trouble with minor discrepancies in outputs when multiple groups are engaged in programcoding of the operating model.
The original target for completion of development
was set at two years with a working schedule asshown in Table 1. Development of management procedures requires intensive efforts by the national
scientists involved in stock assessment. The CCSBTdesired to complete the development within as minimum time frame as possible and in order to concentrate its scientists’ efforts on this task, it agreed to accept a suspension of the full stock assessment in 2002
unless an examination of updated fisheries indicators
suggested a drastic and negative change in the stock(CCSBT, 2001a, b). The same decision was made laterfor 2003 (CCSBT, 2002c, d).
Ana Palma was appointed to the overall coordinator and Vivian Haist, to the consultant for developing
codes who was replaced by Trever Branch in 2005. At
the first Management Procedure Workshop held inMarch 2002, the overall structure of operating model
was determined. The Workshop decided to use themodel structure developed in 1996 as a basis of theoperating model (Butterworth et al., 2003). Single
global stock with age specific natural mortalities, highduring young and low for old, was assumed. The age
specific population dynamics model with natural andfisheries mortalities treated as discrete events was
adopted. Five fisheries, one surface fishery and four
longline fisheries specified with targeting sizes andoperating areas, were defined. The selectivity of thesefisheries was age-specific and estimated in the model.

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S. TSUJI
Table 1 Original time table for development of management procedure (from CCSBT 2002a).
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
9.10
9.11
9.12

Task:
Compile conditioning data
Prepare/debug computer code
Estimate model parameters by conditioning on historical data
Conduct first set of simulation trials using a few simple MP candidates
Meet inter-sessionally to examine model fits and consider the choice of operating
modelsMake code and input parameters (for different operating models) available tonational scientists so that they can test different MPs using chosen set of operating
modelsContinue with MP trials and document results
Hold Workshop II – update data for final conditioning estimations, produce final
specifications of operating models (robustness tests), and consider results for initial
candidate MPs
Continue with MP trials and document results
Inter-sessional meeting – evaluate conditioning and assign weights to alternate
hypotheses (new Step 5, old step 4.5) and consider results for penultimate candidate
MPs
Continue with MP trials and document results
Hold Workshop III – consider results for final candidate MPs and evaluate results,
formulate conclusions and provide advice

The selectivity of the two major fisheries, surface andhigh-sea longline, was allowed to change gradually
every four years. The relationship between recruitments and spawning stock size was assumed to be astochastic Beverton-Holt relationship with autocorrelation in residuals. Technical details of the model
equations and inputs are described in the Attachment
D of CCSBT (2002a). The Workshop also decided thatthe operating model would be developed based on thedata available in 2002, current when the model
development began, and would not be updated interms of data during the development period.
The first version of the operating model was developed based on the specifications decided on at theFirst Management Procedure Workshop. The limited
results of conditioning were presented at the Third
Meeting of the Stock Assessment Group for determination of models to be used for the first phase ofdecision rule testing as well as for further discussion
on more generalized model specifications. Examination of results under various settings revealed thatstock productivity, represented with steepness value(h) in the stock-recruit relationship, and natural mortality for adults are the two key parameters controllingstock dynamics. Since the available data was not
informative enough to estimate either of these parameters, it was decided to use nine sets of conditioning
results with a combination of three steepness values
and three natural mortality values for the first testingof candidate decision rules. Consideration was also
made on generalization of the operating models,
specification of the relationship between stock and
CPUE (catch per unit effort, used as stock abundanceindicator) and how to handle catches and selectivity inthe projection part (see CCSBT, 2002b).
The code needed for the first trials of decisionrules was distributed after the completion of the Third
Meeting of the Stock Assessment Group, and subsequently national scientists explored possible decisionrules. Those results were presented to the Second

Completion by:
May 1, 2002
August, 2002
August, 2002
August, 2002
SAG meeting, September 2002
2 weeks after SAG meeting (may notinclude the posterior distributions for Step
4 initially)
Feb/March, 2003

SAG meeting, September 2003?

March 2004

Meeting of the Management Procedure Workshop
held in April 2003 (CCSBT, 2003a). The decisionrules presented were categorized into model-based
ones, using stock assessment results to determine
future TAC, and empirical ones, determining future
TAC based simply on CPUE trends. There was no
discussion of relative performances among the rules
presented. In fact, at that time, a rather large group ofparticipants including our national scientists was still
struggling to understand the whole concept of management procedures. The majority of the time during
the Meeting was devoted again for the further specification of the operating model. For the model to be
used for the secondary trial of decision rule evaluation,
it was agreed to maintain natural mortality and productivity as the two uncertainty dimensions in conditioning. In addition, a future increase of catchability
was incorporated as the third main uncertainty axis.
Further, a series of scenarios were identified for‘robustness trials’ to examine impacts of events suchas nonlinearity of the stock relationship, alternative
assumptions in targeting and regime shift.
Development of decision rules continued and theresults of the secondary trials were presented at the
Fourth Meeting of the Stock Assessment Group in
August 2003 (CCSBT, 2003b). At this stage, the characteristics of the rules presented varied widely, reflecting the developers’ arbitrary criteria of ‘good’ performance, especially on the relative priority between
catch maximization and stock risk minimization. On
the other hand, it was also noted that the rules presented could be adjusted to attain a certain target, e.g.,stock level. There was a clear trade-off between thecatch amount taken and the attainable stock level. In
order to make candidate rules more comparable, it wasagreed to adjust the rules to attain a pre-specified
median stock level (‘tuning level’) relative to the current after 20 years and three tuning levels of 0.7, 1.1,
and 1.5 were selected. Another focus of discussion
was how to synthesize results obtained from multiple

Development toward the New Management Scheme for Southern Bluefin Tuna

operating model scenarios and an integrative approach
using the MCMC (Monte Carlo Markov Chain) was
adopted. Mortality and steepness were maintained as
key uncertainty axes and a non-linear relationship between stock and CPUE was incorporated as an additional uncertainty axis. An increase in catchability was
now incorporated for both conditioning and projection
parts but to a reduced extent.
The Third Meeting of the Management Procedure
Workshop in April 2004 was aimed at selecting thefinal decision rules among the candidates presented(CCSBT, 2004a). First, the upper and lower limits ofthe tuning levels were noted as unrealistic with an unacceptably high probability of stock collapse for 0.7
and an unrealistically severe TAC reduction for 1.5,
irrespective to the rules, so alternative limits of 0.9
and 1.3 were accepted. Four groups presented theirown candidate rules whose characteristics again reflected the developers’ criteria of ‘good’ performances.
In general, those rules that reduce TAC substantiallyin the early period tended to lead to a TAC increase at
the end of the simulation period, but those rules thatmaintained a gradual TAC reduction in the early
period led to a continuous decline of TAC at the endof the simulation year. A comparison of performance
among candidate rules revealed that the characteristicsof the rules were clustered by developer-group, so
four rules, one from each cluster, were selected forfurther consideration by the Commission.
However, the Meeting also noted that the CPUEs
realized in the last two years were outside the range
expected from the operating model. This implied thatthe operating model based on data up to 2002 could
not predict the actual situation that occurred in 2002
and 2003. This problem was first examined by updating the data, but could not be resolved. Then, theFourth Meeting of the Stock Assessment Group examined the performance of the operating model extensively and concluded that the MCMC favored a possibly unrealistically high natural mortality value(CCSBT, 2004b). Because there was no sound andquick way to fix this problem, the Meeting decided
not to pursue the MCMC but to return to a simple approach of selecting key uncertainties in a grid withpre-specified weightings. The final specification of theoperating model was determined at the Special Management Procedure Technical Meeting held in February 2005 (CCSBT, 2005a) and distributed to the members for refinement of four selected candidate rules forthe final selection at the Fourth Meeting of the ManCCSBT11:
Adoption of
Final MPCCSBT13:Run MP

2004

2006

agement Procedure Workshop in May 2005. The
Fourth Meeting of the Management Procedure Workshop (CCSBT, 2005b) examined improved versions of
the four candidate rules selected at the Third Meeting.
Again, the performance characteristics were moresimilar within the developer-groups than among them.
Subsequently, four rules, one improved version ofeach originally selected candidate, were selected andpresented to the Commission. Those rules will befurther examined after incorporating the most updated
information, especially on recent recruitments, at theforthcoming Stock Assessment Group Meeting andScientific Committee and recommendations will bemade for the final decision at the Commission.
Consultations with managers and industries were
extremely important in developing the management
procedures for two reasons: one, for developing goodunderstanding of procedures and rules that will govern
their ways of living and two, for obtaining feedbackon their preferred options regarding stock management. At the CCSBT, the first consultation with managers and industries was held at the end of the Second
Meeting of the Management Procedure Workshop in
April 2003, where the general concept of management
procedures and the work schedule were explained. In
response to the request from the industries, one of the
Panel members made trips for individual consultationin the member countries to explain the concept of the
management procedures and seek feedback on whatkind of management decisions would be preferablefrom the industries’ point of view. It was noted that
there was no strong desire for an immediate increaseof TAC, but all were strongly opposed to sudden or
substantial reductions in catch. All industries expressed sensitivity to prices as well as high desirability of stability in catch levels (CCSBT, 2003b, c). At
the Tenth Annual Meeting of the CCSBT, the scientists explained the progress made and stated that there
were two key trade-offs in managing the stock, thetrade-off between catch levels and rebuilding of thestock and the trade-off between TAC stability and themagnitude of TAC changes, and asked guidance frommanagers. The Tenth Meeting of the CCSBT agreed to
TAC changes every three years as preferred, with aneed to limit the magnitude of TAC changes and preference for some lead time prior to the first implementation of TAC changes based on the Management
Procedure, and requested to a one-year delay between
decision and implementation of TAC changes with thetime schedule illustrated Fig. 2 as an example. AddiCCSBT 16:
Run MP

1 yearwarning

2005

2007

TAC unchanged forfirst 3 years

CCSBT 19:
Run MP

1 yearwarning

2008

2009

2010

1 yearwarning

2011

TAC fixed for 3 years

TAC
Change

121

2012

2013

TAC fixed for 3 years

TAC
ChangeFig. 2 An example of Management Procedure implementation schedule proposed by
the Tenth Meeting of the CCSBT (from CCSBT, 2003c).

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S. TSUJI

tional performance statistics were also requested fromthe managers (CCSBT, 2003c).
Three management objectives were identified at
the First Meeting of the Management Procedure
Workshop in 2002: maximizing catches, safeguarding
the resource, and minimizing inter-annual variation incatches and efforts. Performance statistics corresponding to each objective were also identified. Originally,
it was tried to minimize the total number of performance statistics. However, the total number of statistics
kept increasing, especially for stock management
objectives, mainly for two reasons. One was that witha lack of pre-specified agreed management target under the CCSBT, the parties wanted to see the performance of the rules relative to their own chosen targets.
Also, the resource safeguarding objective involves
two aspects: one, to reach and maintain a target level
and two, to minimize the risk for the stock declining
to a truly undesirable low level, and separate statistics
are needed to examine both aspects. At this moment, a
total of 17 statistics have been identified, with two forcatch maximization, seven for tracing stock trajectories relative to potential management targets, two for
examining the lowest stock level and four for examining stability of TACs. Statistics are also established to
examine how often the initial direction of TAC change
is reversed later, or whether a stock trajectory and
TAC trajectory show contradictory patterns, though
there are concerns about the interpretation of thosestatistics.

4. Points Noted and Some Considerations
We are now at the final stage of developing theManagement Procedure for the CCSBT. At thismoment, although we are still waiting for the final
selection of decision rules and their adoption by theCommission, most of the tasks required to the scientists have been completed. With this opportunity, I
would like to highlight some of the points that I noted
throughout this experience.
The advantages of management procedures can besummarized as follows:a) to be able to avoid a constant struggle to selectappropriate management action by choosing
pre-specified rules beforehand,b) to be able to take action even when there are substantial uncertainties with regard to the understanding of stock status,c) to be able to evaluate the effectiveness of thoseactions through intensive simulations, andd) to be able to choose management plans by examining the effectiveness of multiple, even contradictory, objectives with a clear understanding oftrade-offs.
Points b) and c) have been emphasized on manyoccasions as aspects in line with the FAO precautionary approach to fisheries management (1996), so here
I will comment on a) and d). In conventional fisheries

management, it is not easy to reach an agreement on
management actions, especially in the international
management schemes for several reasons. Members
generally have different social, economical, and industrial backgrounds and different priorities, even whengathering to manage one common stock. In addition,
most stock assessment can only provide reasonably
reliable estimates of the stock trends but not of theabsolute level of the stock and the future behavior of
the stock. The reliability of the latter two is generally
much worse than that of the estimated relative trends.
Even worse, because the level of precision that managers desire to have, e.g., distinction of impact on
stock caused by 1,000 mt differences in catch, is far
outside that scientists can provide. Unfortunately,
scientists do not answer managers’ questions precisely
and often the two groups use different, mutually incomprehensible languages. The development processof management procedures gives some opportunity toachieve better communication between the two. When
we asked managers to examine the trajectories of 20
scenarios controlled by four candidate rules and to
express their preferences among the four, we found ahigh level of commonality among managers fromvarious countries, especially regarding the least desirable patterns. In this practice, we found that mostmanagers consider multiple factors and objectives
simultaneously in making their judgments. The factthat they only need to choose the rules also seems tocontribute in facilitating their decisions, by obscuring
a linkage between their decisions and TAC that havedirect impact on their industries.
However, the management procedures are not perfect and there are several fundamental limitations.
First, the virtual world used to evaluate rules, theoperating model, is only an extension of the stock
assessment process and has the same problems, i.e.,less reliability regarding absolute estimates and projections. The current operating model developed in the
CCSBT seems to underestimate the absolute stock
abundance, at least in recent years, judging from thefact that a substantial number of the scenarios fail toexplain the actual catch taken in 2004, the most updated catch record that was not included in the operating model conditioning. Regarding to this specificproblem, there was agreement to refine the results of
those scenarios giving a lower stock number than thecatch for 2004 when making the final presentation to
the Commission. However, it should be noted that
overall underestimation of absolute stock levels maylead to an overestimation of sensitivity of stock responses to decision rules.
It should also be noted that management procedures are only valid within the uncertainty range examined. The current process under the CCSBT does
not consider social factors or drastic changes in fishing patterns. In principle, it was decided that whenthose unexpected events arouse, there would be anevaluation of whether the same rules could be main-Development toward the New Management Scheme for Southern Bluefin Tunatained or not. Substantial TAC reductions easily trigger a shift of fishing efforts into a more profitable area,
or a change in targeting size. Shifts in fishing patterns
generally occur much more swiftly than any scientificand management process can respond to them andthose changes may have critical impacts on the performance and credibility of the management procedures．Both managers and scientists need to be prepared to handle this problem before implementing
TAC changes based on the management procedure.
Some evidence indicates that some of the recent
recruitments were substantially lower than previous
levels. Because of these potentially low recruitments,
the overall recognition of the stock status of southern
bluefin tuna and future stock behaviors has shifted
toward serious concern, in contrast with the previous
recognition of the current catch level as being close tosustainable yield. The situation is not easy but we believe that the Management Procedure will be the only
possible way to take prompt actions in response to
stock behavior. We sincerely hope that the CCSBT
will select and adopt one management rule this year asplanned and implement it at the earliest possible time.
References
Butterworth, D. S., J. N.Ianelli and R. Hilborn (2003) A statistical model for stock assessment of southern bluefin tuna withtemporal changes in selectivity. African Journal of Marine
Science,. 25:331-361.
CCSBT (2001a) Report of the Sixth Meeting of the ScientificCommittee (August 2001).
CCSBT (2001b) Report of Eighth Annual Meeting (October2001).
CCSBT (2002a) Report of the First Meeting of Management
Procedure Workshop (March 2002).
CCSBT (2002b) Report of the Third Stock Assessment Group
Meeting (September 2002).
CCSBT (2002c) Report of the Seventh Meeting of the Scientific Committee (September 2002).
CCSBT (2002d) Report of Ninth Annual Meeting (October

1232002).
CCSBT (2003a) Report of the Second Meeting of the Management Procedure Workshop (April 2003).
CCSBT (2003b) Report of the Fourth Stock Assessment Group
Meeting (August 2003).
CCSBT (2003c) Report of Tenth Annual Meeting of the Commission (October 2003).
CCSBT (2004a) Report of the Third Meeting of the Management Procedure Workshop (April 2004).
CCSBT (2004b) Report of the Special Meeting of the Commission (April 2004).
CCSBT (2004c) Report of the Fifth Meeting of the Stock Assessment Group (September 2004).
CCSBT (2004d) Report of the Ninth Meeting of the ScientificCommittee (September 2004).
CCSBT (2004e) Report of Eleventh Annual Meeting of theCommission (October 2004).
CCSBT (2005a) Report of the Special Management Procedure
Technical Meeting (February 2005).
CCSBT (2005b) Report of the Fourth Meeting of the Management Procedure Workshop (May 2005).
CCSBT (2005c) Report of the Management Procedure Special
Consultation (May 2005).
Cooke, J. G. (1999) Improvement of fishery-management advice through simulation testing of harvest algorithms. ICES
Journal of Marine Science, 56:797-810.
FAO (1996) Precautionary approach to fisheries. Part 1: Guidelines on the precautionary approach to capture fisheries andspecies introductions. FAO Fisheries Technical Paper, 350,
Part 1.
Geromont, H. F., J. A. de Oliveira, S. J. Johnston and C. L.
Cunningham (1999) Development and application of management procedures for fisheries in south Africa. ICES Journal of Marine Science, 56:952-966.
Kell, L. T., C. M. O’Brien, M. T. Smith, T. K. Stokes and B.D.
Rackham (1999) An evaluation of management proceduresfor implementing a precautionary approach in the ICES context for North Sea plaice (Pleuronectes platessa L.). ICES
Journal of Marine Science, 56:834-845.
Parma, A. M. (2002) In search of robust harvest rules forpacific halibut in the face of uncertain assessments and decadal changes in productivity. Bulletin of Marine Science,70(2):423-453.
Punt, A. E. and A. D. M. Smith (1999) Harvest strategy evaluation for the eastern stock of germfish (Rexea solandri), ICES
Journal of Marine Science, 56:860-875.

(Received 3 June 2005, Accepted 30 September 2005)

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Annex 1

Definitions of Terminology Used to Discuss Management Procedures(copied from Attachment 5 of CCSBT(2004b))

Operating model:
The operating model is used to represent the population dynamics of SBT based on fits to available data (to2000). These estimates (and the uncertainty) are used as a set of simulations for stock and fishery trajectories inorder to test management procedures.
Nautical analogy: a simulation of ocean and vessel conditions

Reference case:Is the main configuration of the operating model used for testing MPs as agreed at the 2003 SAG held in
Christchurch.
Nautical analogy: the best estimate of ocean and vessel conditions (and the associated unpredictability of theweather)

Robustness trials:
Tests conducted using more challenging scenarios than the reference set.
Nautical analogy: course made good under real (planetary) magnetic anomalies… adding previously unspecified ocean currents…placing uncharted islands in the ocean…

Decision rule:
A rule that specifies how future TACs will change based on data collected. The decision rule specifies the
TAC change but not the magnitude. An Empirical decision rule is driven by data directly. Example: CPUE
goes up, TAC goes up. A Model-based decision rule uses a model (typically a simple model) to analyze thedata and set TACs.
Nautical analogy: the autopilot as purchased (before the voyage).

Management Procedure:
In our context, a MP is a decision rule that has a specified rebuilding target (on average). The MP fully
specifies how TACs will be modified as a function of the new data.
Example: a decision rule adjusted to achieve a spawning biomass in 2022 that is 10% above current.
Nautical analogy: the autopilot set to a specific course.

Metarules:
Rules for evaluating whether or not the implemented MP is performing as anticipated and, if not, what to do.
It includes rules to apply when unexpected circumstances occur.
Nautical analogy: an unexpected reef appears on the bow… The compass was found to be in error…