Assessment of the Southern Zone Abalone · 2017. 12. 11. · Assessment of the Southern Zone Abalone (Haliotis rubra and H. laevigata) Fishery in 2015/16 G.Ferguson, S. Mayfield,

Assessment of the Southern Zone Abalone (Haliotis rubra and H. laevigata) Fishery in 2015/16

G. Ferguson, S. Mayfield, A. Hogg and J. Carroll

SARDI Publication No. F2007/000552-6 SARDI Research Report Series No. 956

SARDI Aquatics SciencesPO Box 120 Henley Beach SA 5022

August 2017

Fishery Assessment Report for PIRSA Fisheries and Aquaculture

Ferguson, G. et al. (2017) Southern Zone Abalone Assessment in 2015/16

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Assessment of the Southern Zone Abalone (Haliotis rubra and H. laevigata) Fishery in 2015/16

Fishery Assessment Report for PIRSA Fisheries and Aquaculture

G. Ferguson, S. Mayfield, A. Hogg and J. Carroll

SARDI Publication No. F2007/000552-6 SARDI Research Report Series No. 956

August 2017


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This publication may be cited as: Ferguson, G., Mayfield, S., Hogg, A. and Carroll, J. (2017). Assessment of the Southern Zone Abalone (Haliotis rubra and H. laevigata) Fishery in 2015/16. Fishery Assessment Report to PIRSA Fisheries and Aquaculture. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2007/000552-6. SARDI Research Report Series No. 956. 62pp.

South Australian Research and Development Institute SARDI Aquatic Sciences 2 Hamra Avenue West Beach SA 5024

Telephone: (08) 8207 5400 Facsimile: (08) 8207 5406 http://www.pir.sa.gov.au/research

DISCLAIMER The authors warrant that they have taken all reasonable care in producing this report. The report has been through the SARDI internal review process, and has been formally approved for release by the Research Chief, Aquatic Sciences. Although all reasonable efforts have been made to ensure quality, SARDI does not warrant that the information in this report is free from errors or omissions. SARDI does not accept any liability for the contents of this report or for any consequences arising from its use or any reliance placed upon it. The SARDI Report Series is an Administrative Report Series which has not been reviewed outside the department and is not considered peer-reviewed literature. Material presented in these Administrative Reports may later be published in formal peer-reviewed scientific literature.

© 2017 SARDI This work is copyright. Apart from any use as permitted under the Copyright Act 1968 (Cth), no part may be reproduced by any process, electronic or otherwise, without the specific written permission of the copyright owner. Neither may information be stored electronically in any form whatsoever without such permission.

Printed in Adelaide: August 2017 SARDI Publication No. F2007/000552-6 SARDI Research Report Series No. 956

Author(s): G. Ferguson, S. Mayfield, A. Hogg and J. Carroll

Reviewer(s): A. Fowler, C. Beckmann (SARDI) and B. McGrath-Steer (PIRSA)

Approved by: T. WardScience Leader – Marine Ecosystems

Signed:

Date: 3 August 2017

Distribution: PIRSA Fisheries and Aquaculture, Southern Zone Abalone Fishery Licence Holders, SAASC Library, SARDI Waite Executive Library, Parliamentary Library, State Library and National Library

Circulation: Public Domain


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TABLE OF CONTENTS ACKNOWLEDGEMENTS ............................................................................................................ VIII EXECUTIVE SUMMARY ................................................................................................................ 1 1 INTRODUCTION ..................................................................................................................... 3

1.1 Background ...................................................................................................................... 3 1.2 History and description of the fishery ............................................................................... 4

1.2.1 Recreational Fishery ............................................................................................... 11 1.2.2 Illegal, unregulated and unreported catch .............................................................. 11 1.2.3 Economic importance ............................................................................................. 11

1.3 Management plan........................................................................................................... 12 1.4 Previous stock assessments .......................................................................................... 13

2 METHODS ............................................................................................................................. 15

2.1 Blacklip ........................................................................................................................... 15 2.2 Greenlip .......................................................................................................................... 15

3 RESULTS .............................................................................................................................. 16

3.1 Blacklip ........................................................................................................................... 16 3.1.1 Southern Zone ........................................................................................................ 16 3.1.2 Spatial assessment units ........................................................................................ 17 3.1.3 Risk of overfishing in SAUs and zonal stock status ............................................... 34

3.2 Greenlip .......................................................................................................................... 36 4 GENERAL DISCUSSION ...................................................................................................... 38

4.1 Current status of blacklip and greenlip in the Southern Zone ....................................... 38 4.1.1 Blacklip .................................................................................................................... 38 4.1.2 Greenlip ................................................................................................................... 39

4.2 Information, data gaps and uncertainty in the assessment ........................................... 39 4.3 Future research needs ................................................................................................... 41

5 REFERENCES ...................................................................................................................... 42 APPENDIX 1 - PERFORMANCE INDICATORS FOR BLACKLIP AND GREENLIP .................. 46 6 APPENDIX 2 – METHODS ................................................................................................... 47 7 APPENDIX 3 – CATCH AND CPUE BY MAPCODE FOR HIGH AND MEDIUM IMPORTANCE SAUS ................................................................................................................... 52 8 APPENDIX 4 - HARVEST STRATEGY PLOTS AND PI SCORES ..................................... 54 9 APPENDIX 5 - CATCH, CPUE AND PROPORTION LARGE FOR BLACKLIP AND GREENLIP .................................................................................................................................... 58


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LIST OF FIGURES

Figure 1-1. Fishing zones and mapcodes of the South Australian Abalone Fishery. ................................... 6 Figure 1-2. Abalone fishing areas (mapcodes, orange polygons on the main map) and exempted (i.e. historic ‘fish-down’, red squares on main map, blue polygons in inset maps) areas in the Southern Zone Abalone Fishery. ........................................................................................................................................... 7 Figure 1-3. Spatial assessment units (SAUs) and mapcodes in the Southern Zone Abalone Fishery ........ 8 Figure 3-1. Total reported catch (tonnes, black bars), effort (hours, red line), CPUE0.3 (kg.hr-1, blue line and circles, and CPUE1 (kg.hr-1, orange line and triangles) on blacklip in the Southern Zone from 1968/69 (denoted 1968) to 2015/16. Horizontal dashed line represents mean CPUE0.3 for the period 1990/01–2009/10. ...................................................................................................................................................... 16 Figure 3-2. Relative importance (ten year % of total catch) of each blacklip (black bars) and greenlip (green bars) SAU in 2015/16. Note each SAU is ranked twice, once for blacklip and once for greenlip. Red text and dotted lines indicate SAU importance and division. ............................................................................. 18 Figure 3-3. Multi-dimensional scaling (MDS) plot for SAUs showing similarity among years based on the spatial distribution of blacklip catch from the Southern Zone from 1979/80 (denoted 1979) to 2015/16. Coloured symbols and ellipses indicate different spatial distributions (SIMPROF; α = 0.05) ..................... 19 Figure 3-4. Bubble plot showing the spatial distribution of the blacklip catch among the SAUs in the SZ from 1979/80 (denoted 1979) to 2015/16. Coloured shading shows year groups with similar spatial distribution of catch. ....................................................................................................................................................... 20 Figure 3-5. The relationship between annual catch and (A) the catch cap (t) and (B) the ten-year average catch (t, 2005/06 to 2014/15) for each SAU in the SZ in 2015/16. (Ad, Admella; Bp, Beachport; BC, Blackfellows Caves; CJ, Cape Jaffa; CR, Carpenters Rocks; EPM, East Port MacDonnell; GB, Gerloffs Bay; MP, Middle Point; NC, Nora Creina; N2R, Number 2 Rocks; PM, Port MacDonnell; RB, Rivoli Bay; SE, Southend). ............................................................................................................................................ 21 Figure 3-6. Reported catch (tonnes, black bars) and CPUE0.3 (kg.hr-1, blue line) on blacklip in Middle Point from 1979/80 (denoted 1979) to 2015/16. .................................................................................................. 22 Figure 3-7. (a) Frequency distributions of shell lengths in recent years and (b) percentage of large (>150 mm SL; black bars) blacklip in the commercial catch from Middle Point from 2001/02 (denoted 2001) to 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place since September 2013. ..................................................................................................................... 23 Figure 3-8. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Middle Point from 2002/03 (denoted 2002) to 2016/17. Surveys were not conducted in 2008/09, 2010/11, 2012/13 or 2013/14. Grey bars show total blacklip. Red and black bars show blacklip 150 mm SL) blacklip (b) in the commercial catch from Gerloffs Bay between 2001/02 (denoted 2001) and 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place sinceSeptember 2013. ......................................................................................................................................... 25 Figure 3-11. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Gerloffs Bay from 2002/03 (denoted 2002) to 2016/17. Surveys were not conducted in 2008/09, 2010/11, 2012/13, and 2013/14. Grey bars show total blacklip. Red and black bars show blacklip 150 mm SL) blacklip (b) in the commercial catch from Number 2 Rocks between 2001/02 (denoted 2001) and 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place since September 2013. ..................................................................................................................... 27


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Figure 3-14. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Number Two Rocks in 2014/15 (denoted 2014) and 2016/17. No surveys was conducted in 2013/14. Grey bars show total blacklip. Red bars show blacklip 150 mm SL; black bars) blacklip in the commercial catch from the Rivoli Bay, Admella, Carpenters Rocks and Port MacDonnell SAUs between 2001/02 (denoted 2001) and 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place since September 2013. Note scales on Y-axes vary among SAUs.* indicates insufficient data. .............................................................................. 32 Figure 3-17. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Rivoli Bay from 2002/03 (denoted 2002) to 2016/17. Surveys were not conducted in 2008/09, 2010/11, and 2013/14. Grey bars show total blacklip. Red and black bars show blacklip 160 mm SL) greenlip in the SZ commercial catch from 2001/02 (denoted 2001) to 2015/16. X-axis labels in panel (a) show the upper limit of each size class. Vertical red dashes represent MLL of 130 mm SL. .................................... 37 Figure 3-21. Density of greenlip (abalone.m-2; all length classes combined) from fishery-independent surveys in the Rivoli Bay SAU from 2002/03 to 2016/17. Surveys were not conducted in 2008/09, 2010/11, 2013/14, 2015/16. ....................................................................................................................................... 37 Figure A3-1. Bubble plot of catch (t) by mapcode for high and medium importance SAUs in SZ blacklip fishery……………………………………………………………………………………………………………………………………….52

Figure A3-2. (A) Catch by mapcode, and (B) CPUE1 by mapcode, for the high importance SAU Middle Point……………………………………………………………………………………………………………………………………………....52

Figure A3-3. Catch by mapcode, for the High Importance SAU Number 2 Rocks......................................53

Figure A3-4. (A) Catch by mapcode, and (B) CPUE1 by mapcode, for the medium importance Admella SAU…………………………………………………………………………………………………………………………...…………………..53

Figure A4-1. Middle Point SAU (high importance). Performance indicators (and scores from the harvest strategy to determine the risk of being overfished) and upper and lower target (red lines) and limit (blue dashed lines) reference points. Black bars show the data and time over which the reference points were calculated. Open bars describe measures of the PI outside of the reference period. Yellow bars indicate the data and year subject to assessment for each PI i.e. the score-year……………………………………………..54

Figure A4-2. Gerloffs Bay SAU (high importance). Performance indicators (and scores from the harvest strategy to determine the risk of being overfished) and upper and lower target (red lines) and limit (blue dashed lines) reference points. Black bars show the data and time over which the reference points were calculated. Open bars describe measures of the PI outside of the reference period. Yellow bars indicate the data and year subject to assessment for each PI i.e. the score-year……………………………………………..55

Figure A4-3. Number 2 Rocks SAU (high importance). Performance indicators (and scores from the harvest strategy to determine the risk of being overfished) and upper and lower target (red lines) and limit (blue dashed lines) reference points. Black bars show the data and time over which the reference points were


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calculated. Open bars describe measures of the PI outside of the reference period. Yellow bars indicate the data and year subject to assessment for each PI i.e. the score-year………………………………………………56

Figure A4-4. Rivoli Bay, Admella, Carpenters Rocks and Port MacDonnell SAUs (medium importance). Performance indicators (and scores from the harvest strategy to determine the risk of being overfished) and upper and lower target (red lines) and limit (blue dashed lines) reference points. Black bars show the data and time over which the reference points were calculated. Open bars describe measures of the PI outside of the reference period. Yellow bars indicate the data and year subject to assessment for each PI i.e. the score-year………………………………………………………………………………………………………………………………………57

LIST OF TABLES

Table 1-1. National stock status reporting framework classifications (from Stewardson et al. 2016). ......... 3 Table 1-2. Management milestones in the Southern Zone of the South Australian Abalone Fishery. (Blacklip, BL; Greenlip, GL). .......................................................................................................................... 9 Table 1-3. For blacklip in each SAU: catch caps (shell weight), and current minimum legal shell lengths (MLLs) in place from 1 September 2015, (2015/16 season). Also shown are historical MLLs for the areas inside and outside of the historical fishdown areas (FDAs) and associated mapcodes (MC) prior to 2013/14. .................................................................................................................................................................... 10 Table 3-1. Outcome from application of the harvest strategy described in the Management Plan for the blacklip fishery in the SZ. Grey shading identifies the performance indicators and their respective scores. .................................................................................................................................................................... 35 Table A2 Summary of the formulae and data constraints underpinning their utilisation in the harvest strategy………………………………………………………………………………………………………………………………….46

Table A5.1 Blacklip catches (tonnes) by season from the Southern Zone abalone fishery, aggregated at zonal and spatial assessment unit scales, ordered by importance………………………………………………………58

Table A5.2 Blacklip catch per unit effort (CPUE) catches by season from the Southern Zone abalone fishery, aggregated at zonal and spatial assessment unit scales, ordered by importance. na indicates estimate not available for that year………………………………………………………………………………………………………………………59

Table A5.3 Proportional (%) contribution to total blacklip catch by spatial assessment units, ordered by importance. Background represents the range from minimum to maximum with the minimum value (0%) shown as red, the maximum value (48%) as blue, and the median (4%) as white, with all other values coloured proportionally…………………………………………………………………………………………………………………….60

Table A5.4 Proportion of large Blacklip (>150 mm SL) in commercial catch samples from spatial assessment units (SAU) in the Southern Zone abalone fishery, ordered by importance. na indicates estimate unavailable for that year……………………………………………………………………………………………………..61

Table A5.5. Greenlip catches (tonnes) by season from the Southern Zone abalone fishery, aggregated at zonal and spatial assessment unit scales, ordered by importance……………………………………………………….62

Table A5.6. Proportion of large Greenlip (>160 mm SL) in commercial catch samples from the Southern Zone abalone fishery………………………………………………………………………………………………………………………..62


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ACKNOWLEDGEMENTS

Funds for this research were provided by PIRSA Fisheries and Aquaculture, obtained through

licence fees. We are grateful to Brian Foureur, Peter Hawthorne, Kylie Howard and Damian

Matthews, and other SARDI divers, past and present, for assistance with diving and the collection

and management of data. We thank Angelo Tsolos and Millie Boyle for statistical support. We

thank the Southern Zone licence holders and fishers for providing abalone shells that were used

for length measurements and for their contribution to our understanding of the information

presented in this report. This report was formally reviewed by Belinda McGrath-Steer (PIRSA

Fisheries and Aquaculture), Drs Tony Fowler and Crystal Beckmann (SARDI Aquatic Sciences)

and Prof. Gavin Begg, Research Chief, SARDI Aquatic Sciences. The report was formally

approved for release by A/Professor Tim Ward, Science Leader, Marine Ecosystems and Pelagic

Fishes, SARDI Aquatic Sciences.


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EXECUTIVE SUMMARY

This fishery assessment report updates the 2015 report and assesses the status of blacklip

(Haliotis rubra) and greenlip (Haliotis laevigata) abalone in the Southern Zone (SZ) of the South

Australian Abalone Fishery (SAAF) for 2015/16.

This assessment is required under the Management Plan of the SAAF (PIRSA 2012). A review

of the harvest strategy (PIRSA 2012) is in progress and due for completion by 31 December 2017.

The stock status was determined through a weight-of-evidence analysis using the National

Fishery Status Reporting Framework (NFSRF; Flood et al. 2014; Stewardson et al. 2016).

Blacklip abalone

Prior to 2011/12, the SZ blacklip fishery was characterised by stable catches, spatial distributions

of catches, and commercial and fishery-independent (FI) length frequencies. Considerable

changes occurred from 2012/13 to 2013/14, including declining catch rates, lower proportions of

large blacklip in the catch and consequent status of key spatial assessment units (SAUs). This

resulted in the SZ blacklip fishery being classified as ‘transitional depleting’ under the NFSRF in

2013/14 and 2014/15. In response, the total allowable commercial catch (TACC) was reduced

from 151.5 t (16.8%) to 126 t for 2015/16 and 2016/17.

Despite the reduced TACC in 2015/16, there is strong evidence that the SZ blacklip fishery

remains in a poor position: (1) the TACC was not fully harvested in 2013/14 (83%) and 2014/15

(89%); (2) catches and catch rates remained low or declined in many SAUs; (3) catches were

redistributed among SAUs and mapcodes within SAUs; (4) proportions of large blacklip in catches

from many SAUs remained low or declined (exceptions were Middle Point and Number 2 Rocks);

and (5) recent FI estimates of sub-legal and legal-sized densities from FI surveys were relatively

low in two of three key SAUs (Middle Point, Gerloffs Bay) in 2014/15 and 2016/17. The output

from the harvest strategy (PIRSA 2012) classified the SZ blacklip fishery as ‘over fished’.

Collectively, this evidence demonstrates that the harvestable biomass is declining and that fishing

pressure is too high. As the stocks are not yet considered to be recruitment overfished, the SZ

blacklip fishery remains classified as ‘transitional depleting’ under the NFSRF (Flood et al. 2014; Stewardson et al. 2016), which is consistent with the stock status classification in 2013/14

and 2014/15.


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Greenlip abalone

Due to the low current and historical catch and limited data available for greenlip in the SZ, the

stock status for this species is classified as 'undefined' under the NFSRF (Flood et al. 2014; Stewardson et al. 2016).

Key statistics for the SZ blacklip and greenlip fisheries from 2013/14 to 2015/16 including stock status based on (i) the harvest strategy in the Management Plan (HS) and (ii) weight of evidence and the national fishery stock status reporting framework (NFSRF).

Blacklip Greenlip

Season No. licences TACC Catch CPUE Stock Status TACC Catch CPUE Stock Status

(t) (t) (kg.hr-1) HS NFSRF (t) (t) (kg.hr-1) HS NFSRF

2013/14 6 151.5 126 91.0 Sustainably fished Transitional depleting 7.2 3.6 na na Undefined

2014/15 6 151.5 135 90.2 Sustainably fished Transitional depleting 7.2 4.4 na na Undefined

2015/16 6 126.0 122.6 91.0 Over fished Transitional depleting 6.0 3.7 na na Undefined

Keywords: Blacklip abalone (Haliotis rubra), Greenlip abalone (Haliotis laevigata), Stock Assessment, Harvest Strategy, Stock Status, South Australia.


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1 INTRODUCTION

1.1 Background

This fishery assessment report for blacklip (Haliotis rubra) and greenlip (Haliotis laevigata)

abalone, hereafter referred to as blacklip and greenlip, respectively, in the Southern Zone (SZ) of

the South Australian Abalone Fishery (SAAF; Figure 1-1) updates previous fishery assessment

(Mayfield et al. 2015) and status reports (Ferguson et al. 2016) for the SZ. The aims of the report

are to (1) document the current status of the resource; (2) identify the uncertainty associated with

the assessment; (3) evaluate the harvest strategy for the fishery; and (4) identify future research

needs.

The report provides an analysis of fishery-dependent (FD) and fishery-independent (FI) data from

1 September 1968 to 31 August 2016 and is part of the South Australian Research and

Development Institute (SARDI) Aquatic Sciences’ ongoing assessment program for the blacklip

and greenlip fisheries in the SZ.

Table 1-1. National stock status reporting framework classifications (from Flood et al. 2014; Stewardson et al. 2016).

Stock status Description Potential implications for management of the stock

Sustainable Stock for which biomass (or biomass proxy) is at a level sufficient to ensure that, on average, future levels of recruitment are adequate (i.e. not recruitment overfished) and for which fishing pressure is adequately controlled to avoid the stock becoming recruitment overfished

Appropriate management is in place

Transitional - recovering

Recovering stock—biomass is recruitment overfished, but management measures are in place to promote stock recovery, and recovery is occurring

Appropriate management is in place, and the stock biomass is recovering

Transitional - depleting

Deteriorating stock—biomass is not yet recruitment overfished, but fishing pressure is too high and moving the stock in the direction of becoming recruitment overfished

Management is needed to reduce fishing pressure and ensure that the biomass does not deplete to an overfished state

Overfished Spawning stock biomass has been reduced through catch, so that average recruitment levels are significantly reduced (i.e. recruitment overfished). Current management is not adequate to recover the stock, or adequate management measures have been put in place but have not yet resulted in measurable improvements

Management is needed to recover this stock; if adequate management measures are already in place, more time may be required for them to take effect

Environmentally limited

Spawning stock biomass has been reduced to the point where average recruitment levels are significantly reduced, primarily as a result of substantial environmental changes/impacts, or disease outbreaks (i.e. the stock is not recruitment overfished). Fisheries management has responded appropriately to the environmental change in productivity

Appropriate management is in place

Undefined Not enough information exists to determine stock status Data required to assess stock status are needed


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1.2 History and description of the fishery

A review of the management history of the SAAF since its inception in 1964 is provided by

Mayfield et al. (2012) with further detail provided in several previous publications (Prince and

Shepherd, 1992; Zacharin, 1997, Shepherd and Rodda, 2001; Nobes et al., 2004; Mayfield and

Hogg, 2011; Mayfield et al., 2013). Major management milestones are listed in Table 1-2. Briefly,

entrants to the fishery increased in the late 1960s, and exceeded 100 operators by 1970. Licences

were made non-transferrable in 1971 to reduce the number of operators. By 1976, the number

had fallen to 30 and an additional 5 licences were issued. These 35 licences remained until 2013.

From 1 January 2014, removal of one licence – as part of the voluntary marine park buy-back

scheme – reduced the total number of licences in the SAAF to 34.

In 1971, the SAAF was divided into three zones (Western; Central; and Southern, SZ; Figure 1-1).

The SZ includes all coastal waters of South Australia east of Meridian 139°E, with the exception

of the Coorong and waters inside the Murray River mouth. The fishing season runs from 1

September to 31 August. Total Allowable Commercial Catches (TACCs) were introduced in 1988,

with most of the TACC in the SZ comprised of blacklip (Table 1-2). In 2014/15, the blacklip TACC

was 151.5 t whole weight and the greenlip TACC was 7.2 t whole weight, but both were reduced

for 2015/16 (blacklip: by 20% from 151 t to 126 t; greenlip: by 17% from 7.2 t to 6 t).

From 1 September 2013, substantial changes occurred to the management arrangements for the

SZ abalone fishery, following completion of an FRDC-funded project (FRDC 2004/019; Mayfield

and Saunders 2008) and extensive consultation through 2012 and 2013. Key among these

changes was the implementation of spatial management, with area-specific minimum legal

lengths (MLLs) and catch caps that followed an extensive program that evaluated spatial

variability in blacklip across this zone (Mayfield and Saunders 2008; Saunders and Mayfield 2008;

Saunders et al. 2009a; 2009b). There were three key changes: (1) fish-down areas (FDAs) were

removed (Figure 1-2); (2) 13 Spatial Assessment Units (SAUs) were identified, that spanned

different mapcode amalgamations (Figure 1-3); and (3) individual MLLs, catch targets and catch

caps were allocated to each SAU (Table 1-3). These changes recognised the spatial distribution

of abalone populations with different morphology and biology across the SZ (Mayfield and

Saunders 2008) and reflect approaches adopted elsewhere (e.g. Prince et al. 2008).

Commercial catch and effort data on this fishery have been collected since 1968. Licence holders

and/or divers submit daily catch and effort data to SARDI Aquatic Sciences at the end of each


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month using the research logbook. The logbook provides information on the date of fishing,

fishing area, amount of time spent fishing, whether or not an underwater vehicle was used, diving

depth and total catch landed. Few changes have been made to the data collection system.

However, in 1978, sub zones and fishing blocks were replaced by spatially smaller map numbers

(Fishing Areas; FA) and mapcodes (Figure 1.2). Supplementary, voluntary, data fields (e.g. GPS

position, number of abalone harvested) were added to the logbook in 2002. The logbook data

supplied by divers and licence holders are used by SARDI Aquatic Sciences for analyses of catch,

effort and catch-per-unit-effort (CPUE) data that underpin assessments of the fishery for each

zone for Primary Industries and Regions South Australia - Fisheries and Aquaculture (hereafter

referred to as Fisheries and Aquaculture).


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Figure 1-1. Fishing zones and mapcodes of the South Australian Abalone Fishery.


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Figure 1-2. Abalone fishing areas (mapcodes, orange polygons on the main map) and exempted (i.e. historic ‘fish-down’, red squares on main map, blue polygons in inset maps) areas in the Southern Zone Abalone Fishery.


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Figure 1-3. Spatial assessment units (SAUs) and mapcodes in the Southern Zone Abalone Fishery


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Table 1-2. Management milestones in the Southern Zone of the South Australian Abalone Fishery. (Blacklip, BL; Greenlip, GL).

Season Milestone

1964 Fishery started 1971 Licences made non-transferable

Fishery divided into three zones Minimum legal length set at 130 mm shell length (SL) for both species

1976 30 Licences remained; 5 additional licences issued 1978 Sub Zones and fishing blocks replaced by map numbers and codes 1984 Blacklip minimum legal length amended to 120 mm SL in the Southern Zone 1988 Quota introduced to the SZ

Blacklip minimum legal length amended to 125 mm SL in the Southern Zone 1993 Abolition of owner-operator regulation 1994 Four ‘fish-down’ areas defined in the Southern Zone 1997 Management Plan implemented 2003 SZ separated into ‘fish-down’ and non-‘fish-down’ areas with separate TACC 2004 Management Plan Revised 2004 Fishery assessed against the principles of ecologically sustainable development 2005 Greenlip TACC increased from 3 to 6 t

Blacklip TACC in non-FDAs increased from 96 to 99 t Blacklip TACC in the FDAs reduced from 51 to 45 t

2010 Greenlip TACC increased from 6 to 7.2 t 2011 Blacklip TACC in the FDAs increased from 45 to 46.5 t 2011 Blacklip TACC in non-FDAs increased from 99 to 105 t 2012 New Management Plan including harvest strategy 2012 Blacklip TACC in FDAs increased from 45 t to 46.5 t 2012 Zonal TACCs for BL and GL were 105 t and 7.2 t, respectively 2013 Amalgamation of mapcodes into 13 SAU individual MLLs, catch targets and catch limits 2013 Zonal TACC for BL and GL were 151.5 t and 7.2 t, respectively 2014 Zonal TACC for BL and GL were 151.5 t and 7.2 t, respectively 2015 Zonal TACC for BL reduced by 16.8% from 151.5 t to 126 t. Zonal TACC for GL decreased from 7.2 t to 6 t. 2016 Zonal TACC for BL and GL were 126 t and 3.6 t, respectively.


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Table 1-3. For blacklip in each SAU: catch caps (shell weight), and current minimum legal shell lengths (MLLs) in place from 1 September 2015, (2015/16 season). Also shown are historical MLLs for the areas inside and outside of the historical fishdown areas (FDAs) and associated mapcodes (MC) prior to 2013/14.

SAU Mapcodes 2015/16 Catch cap (t)

2015/16 Minimum legal length (SL, mm) Historical minimum legal length outside/within FDA (SL, mm)

Cape Jaffa 33A, 33B, 33C, 34A, 34B, 34C - 125 125

Nora Creina 34D, 35A, 35B, 35C, 35D 8 125 125

Beachport 35E, 36A 6 125 125

Rivoli Bay 36B 12 120 125 (outside FDA 3); 110 (FDA 3)

South End 36C 8 125 125

Number 2 Rocks 37A, 37B, 37C, 37D, 37E, 37F, 37G, 37H 30 125 125

Admella 37J, 39A 16 120 125

Carpenters Rocks 39B, 39C 12 125 125 (outside FDA 4); 110 (FDA 4)

Gerloffs Bay 39D 30 120 110 (FDA 4)

Blackfellows Caves 39E 5 125 125 (outside FDAs 1 and 4); 110 (FDA 4; FDA 1)

Middle Point 39F, 39G, 40A 35 120 125 (outside FDA 1); 110 (FDA 1)

Port MacDonnell 40B 15 120 125 (outside FDA 2); 110 (FDA 2)

East Port MacDonnell 40C, 40D 3 110 125 (outside FDA 2); 110 (FDA 2)


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1.2.1 Recreational Fishery The total recreational abalone harvest in South Australia was estimated at 17,780 abalone.yr-1 for

2000/01 (Henry and Lyle 2003). Previous surveys within South Australia suggested that 19.5% of

recreational fishing effort was expended in the SZ (Mayfield et al. 2001). Under this assumption,

approximately 3,500 abalone (1.6 t) are recreationally harvested from the SZ annually. This

represents about 1.06% of the TACC. A creel survey undertaken in 2007/08 estimated the total

recreational harvest in the SZ at


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Major costs within the SAAF include interest, management costs and fuel. The average cost of

management per licence holder has remained relatively stable since 2004/05 and ranged

between $72,438 and $86,156 from 2004/05 to 2014/15 (Magnusson et al. 2016). The average

costs per kilogram of catching Abalone also followed a downward trend, with some fluctuations,

from 2000/01 to 2014/15 (Magnusson et al. 2016).

1.3 Management plan

The second Management Plan for the SAAF (Nobes et al. 2004) was reviewed and replaced in

2012 by the current Management Plan (PIRSA 2012) that is undergoing review with

recommendations due in 2017. This Management Plan stipulates the management goals and

objectives for the fishery that reflect current policy drivers including Section 7 of the Fisheries

Management Act 2007, Ecologically Sustainable Development as described in the Environmental

Protection and Biodiversity Act 1999 and the precautionary principle.

The four management goals are to ensure: (1) the abalone resource is sustainably harvested; (2)

optimal economic utilisation and equitable distribution of the abalone resource; (3) impacts on the

ecosystem are minimised; and (4) cost effective and participative management of the fishery. This

report is directly relevant to the first goal, for which the objectives are to: (1) maintain the stocks

above ecologically sustainable levels; and (2) ensure sufficient data and information are available

to undertake the harvest strategy which underpins the management decisions. The harvest

strategy is the primary tool used to achieve the goal of sustainably harvesting the abalone

resource and it is described elsewhere (PIRSA 2012; Chick and Mayfield 2012; Mayfield et al.

2013; 2015). Briefly, it is species-specific, spatially-explicit and comprises two key components.

First, performance indicators (PIs) are used with a series of reference points to determine the risk

that the stocks in each SAU are overfished (Figure 1-3). Detailed descriptions of the formulae and

data exclusion rules for estimating PIs are given in Appendix 1. Second, the assigned risks that

the stocks are overfished are catch-weighted and summed to determine the status of that stock

for each zone. The stock status enables the TACC to be set for two years – concurrent with the

biennial assessment program – providing that zonal stock status does not change between years.

The outcomes from the harvest strategy are used in the decision-making process which integrates

information from multiple sources (e.g. divers, licence holders, fishery managers, compliance

officers, researchers) to make management decisions for each SAU. The range of management

decisions for each SAU is constrained by explicit decision rules based on the assigned risk-of


13

overfishing category (PIRSA 2012). These harvest-decision rules guide determination of future

catch contributions from each SAU in the fishery that are then summed by species for each zone

and used to adjust annual TACCs.

1.4 Previous stock assessments

The first assessment of the South Australian abalone resource was published by the South

Australian Department of Fisheries in 1984 (Lewis et al. 1984). In 1996, abalone research

arrangements were comprehensively reviewed (Andrew 1996) and fishery reports were produced

annually from 1998 to 2000 (Rodda et al. 1998; 2000; Shepherd et al. 1999). The 2001 stock

assessment report provided fishery statistics for all three zones of the fishery (Mayfield et al. 2001)

and provided the basis for more detailed stock assessments for each zone during 2002 (Mayfield

et al. 2002a,b; Mayfield and Ward 2002). The first dedicated SZ report (Mayfield et al. 2002a)

synthesised all data for the SZ from 1968 to 2002. That report has since been updated regularly

(Mayfield et al. 2003, 2004, 2005, 2006, 2007), with recent reports providing detailed analyses for

both FDA and non-FDA (Mayfield et al. 2005, 2006, 2007, 2009, 2013; Mayfield and Hogg 2011).

Historically, assessments of the status of SZ stocks were heavily weighted by commercial catch

and effort data (see Mayfield et al. 2002a, 2003, 2004, 2005, 2006). This assessment, like those

undertaken since 2007 (Mayfield et al. 2007, 2009, 2013; Mayfield and Hogg 2011), is more robust

as the assessment information is better balanced between that provided by commercial fishers

(e.g. catch and effort and catch-sampling data) and that collected by SARDI Aquatic Sciences

(i.e. biological and FI-survey data).

The 2013 report assessed the fishery against the new harvest strategy based on SAUs and also

provided an evaluation of the harvest strategy (PIRSA 2012; Mayfield et al. 2013). This

assessment concluded that blacklip stocks in the SZ were in a strong position but noted that the

impact of widespread blacklip mortality in 2011/12 had not been determined and the ongoing

capacity for blacklip populations to support historical catches remained unknown (Mayfield et al.

2013). The stock status report in 2014 reflected a decline in the estimates of CPUE for the SZ

and most SAUs across the 2011/12 and 2012/13 fishing seasons, although levels of CPUE

remained historically high (Mayfield et al. 2014).

The stock assessment in 2015 noted that considerable changes had occurred in the SZ since

2013/14 including declining CPUE; re-distribution of catches among SAUs; lower percentages of

large blacklip in commercial catch samples, and from fishery-independent (FI) surveys; and

reductions in blacklip density estimates from FI surveys. In 2013/14, the TACC was not harvested


14

and the blacklip fishery was classified as “transitional depleting”. The TACC was also not

harvested in 2014/15 and, for 2015/16, the TACC for blacklip was reduced by 16.8% from 151.5

t to 126 t and the TACC for greenlip was reduced from 7.2 t to 6 t.


2 METHODS

Fishery-dependent (FD) and FI data are available for assessment of the SZ blacklip and greenlip

fisheries. Details on data quality assurance and the methods used for analysing the FD and FI

data are provided in Appendices 1–3. Briefly, the FD data have been collected since 1968 by

fishers completing a catch and effort logbook for each fishing day and providing access to

commercial catches from which catch length-frequency data have been obtained from September

2001 to August 2016. Fishery statistics are provided at two spatial scales, the whole of the SZ,

and individual SAUs.

2.1 Blacklip

To account for the multiple changes in MLLs for blacklip over years, commercial catch sampling

data were restricted (to standard length; SL ≥ 125 mm SL) and proportion large defined as those

SLs greater than 150 mm SL (Appendix 1). Fishery statistics are provided at two spatial scales,

the whole of the SZ, and individual SAUs (Figure 1-3). For the zone, CPUE was computed using

two methods. These were using all days when blacklip was at least 70% of the total catch

(CPUE0.3) and all days when no greenlip were harvested (i.e. blacklip 100% of the catch; CPUE1).

Fishery-independent data consisted of (1) estimates of blacklip densities for sub-legal-sized and

legal-sized individuals separately (variable by SAU to account for spatial variation in MLL) and

collectively (i.e. total density); and (2) population length-frequency distribution. Inclement weather

prevented access to all survey sites in 2016/17. Consequently, the sub-sets of historical data

were constructed to match the 2016/17 sampling locations, and historical density estimates

recalculated.

All data are presented as mean ± standard error (se) unless otherwise stated.

2.2 Greenlip

Fishery-dependent data consisted of annual SZ catches and catches from the key SAUs from

which greenlip are caught (Gerloffs Bay, Rivoli Bay, Nora Creina Bay and East Port MacDonnell

SAUs). Additionally, proportion large was defined as those SLs greater than 160 mm SL in the

commercial catch (Appendix 1).

15


16

3 RESULTS

3.1 Blacklip

3.1.1 Southern Zone

From 1969/70 to 1993/94, which comprised the early, formative years of the SZ fishery, catches

of blacklip ranged from 19–186 t.yr-1 (mean: 109 t.yr-1, Figure 3-1). From 1994/95 to 2011/12, total

annual catches were relatively stable and generally higher (range: 142–151 t.yr-1; mean: 144 t.yr-1)

than the preceding 25 years. The catch of 149 t in 2012/13 was close to the contemporary

maximum of 151 t in 2011/12. However, in 2013/14 and 2014/15, the catches of 126 t and 135 t

respectively, comprised 83% and 89% of the TACC (151.5 t). In 2015/16, the catch of 122.6 t

accounted for 97% of the reduced (16.8%) TACC of 126 t, the lowest since 1991/92.

Total annual effort was 1,997 hours (hr) in 1992/93, which was the highest on record (Figure 3-1).

From 1992/93, total annual effort declined substantially (>30%) and, since 2008/09 has been

approximately 1,400 hr.y-1 among years.

Figure 3-1. Total reported catch (tonnes, black bars), effort (hours, red line), CPUE0.3 (kg.hr-1, blue line and circles, and CPUE1 (kg.hr-1, orange line and triangles) on blacklip in the Southern Zone from 1968/69 (denoted 1968) to 2015/16. Horizontal dashed line represents mean CPUE0.3 for the period 1990/01–2009/10.

From 1993/94 to 2010/11, the combination of stable catches and reductions in fishing effort

resulted in increasing catch rates and mean annual CPUE0.3 (i.e. CPUE estimated from days

Fishing season

1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

50

100

150

200Ef

fort

(hr)

600

800

1000

1200

1400

1600

1800

2000

2200

CPU

E (k

g.hr

-1)

0

20

40

60

80

100

120

Catch Effort CPUE0.3 CPUE1


17

when blacklip comprised ≥30% of the catch) exceeded 100 kg.hr-1 from 2008/09 to 2011/12

(Figure 3-1). The CPUE0.3 of 114 kg.hr-1 in 2010/11 was the highest in 30 years (i.e. since

1979/80). From 2010/11, CPUE0.3 declined (20%) over four consecutive seasons to 90 kg.hr-1 in

2014/15, the lowest since 2001/02. In 2015/16, CPUE0.3 increased by 1% to 91 kg.hr-1. For

CPUE1, (i.e. CPUE estimated from days when only blacklip were caught) annual estimates were

generally slightly higher than for CPUE0.3 but temporal trends were correlated (Pearson

Correlation Coefficient, PCC: 0.99, p


18

Figure 3-2. Relative importance (ten year % of total catch) of each blacklip (black bars) and greenlip (green bars) SAU in 2015/16. Note each SAU is ranked twice, once for blacklip and once for greenlip. Red text and dotted lines indicate SAU importance and division.

Spatial Assessment Unit

Midd

le Po

int

Numb

er 2 R

ocks

Gerlo

ffs Ba

yAd

mella

Rivoli

Bay

Carpe

nters

Rock

s

Port M

acDo

nnell

Beac

hport

South

End

Black

fellow

s Cav

esNo

ra Cr

eina

Gerl

offs B

ay R

ivoli B

ay N

ora C

reina

Cape

Jaffa

Cap

e Jaff

a

East

Port M

acdo

nnell

Unas

signe

d SZ

Midd

le Po

int

Carp

enter

s Roc

ks Ad

mella

Port M

acdo

nnell

Blac

kfello

ws C

aves

East

Port M

acdo

nnell

Beac

hport

South

End

Una

ssign

ed SZ

Num

ber 2

Roc

ks%

of t

otal

cat

ch

0

5

10

15

20

25

BL GL

High Medium Low


19

3.1.2.1 Distribution of catch among spatial assessment units

From 1979/80 to 2015/16, there were five periods in which the distribution of blacklip catches

among SAUs was similar (i.e. MDS; Figures 3-3, 3-4) i.e. the proportional distribution of catches

among SAUs differed among these periods (SIMPROF, α=0.05). The longest period of similar

spatial distribution of catches occurred from 1994/95 to 2012/13, which is generally consistent

with the 20-year reference period used in the harvest strategy (1990/91–2009/10). During this

period, total catches were stable (range 134–186 t.y-1; mean 146 ± 2.1 t.y-1), and combined

catches from Middle Point (24%), Gerloffs Bay (17%), and Number 2 Rocks (15%) contributed

55% of total catches.

From 2013/14 to 2015/16, the combined contribution from Middle Point (26%), Gerloffs Bay (7%),

and Number 2 Rocks (18%) was 51% of total catches (Figure 3-4). Also during this period,

contributions to the total catch from Port MacDonnell (12%) and Admella (12%) had increased

compared to the period from 1994/95 to 2012/13, when they were 2.4% and 7.8%, respectively.

Within the MDS ordination, the spatial distribution of catches from 2013/14 to 2015/16 was

equidistant between the prolonged period of stable catches (1994/95 to 2012/13) and the early

years of the fishery (1978/79–1983/84). This was likely due to the proportionally high contributions

from Middle Point and Number 2 Rocks, and low contribution from Gerloffs Bay in those periods.

Figure 3-3. Multi-dimensional scaling (MDS) plot for SAUs showing similarity among years based on the spatial distribution of blacklip catch from the Southern Zone from 1979/80 (denoted 1979) to 2015/16. Coloured symbols and ellipses indicate different spatial distributions (SIMPROF; α = 0.05)

1978

1979

1980

1981

1982

1983

1984

1985

19861987

1988

1989

1990

1991

1992

19931994

1995

1996

1997

1998

1999

2000

2001

2002

20032004

2005

2006

2007

200820092010

2011

2012

2013

2014

2015

2D Stress: 0.18


20

Figure 3-4. Bubble plot showing the spatial distribution of the blacklip catch among the SAUs in the SZ from 1979/80 (denoted 1979) to 2015/16. Coloured shading shows year groups with similar spatial distribution of catch.

Catches in 2015/16 were below the catch cap in all SAUs, with the exception of the Port

MacDonnell (Figure 3-5A). For the three high importance SAUs, Middle Point, Number 2 Rocks,

and Gerloffs Bay, catches were 25%, 7%, and 48% below their respective catch caps. Exceptions

were Port MacDonnell, the three remaining medium importance SAUs Admella, Rivoli Bay, and

Carpenters Rocks were 16%, 66% and 17%, respectively below their catch caps.

In 2015/16, the high importance SAUs of Gerloffs Bay (10%) and Middle Point (1%) contributed

less to the total catch than the mean contribution in the previous 10 seasons (10-year average,

2005/06 to 2014/15; Figure 3-5B). Conversely, the contribution by the remaining high importance

SAU, Number Two Rocks, to the total catch was 7% greater than the 10-year average. Among

medium importance SAUs, the contribution from Rivoli Bay was 6% less than the 10-year

average. Catches from the low importance SAUs Carpenters Rocks, Admella and Port

MacDonnell were respectively, 6%, 2% and 2% greater than the 10-year average.

Fishing season

1980 1985 1990 1995 2000 2005 2010 2015

Spat

ial A

sses

smen

t Uni

t

East Port Macdonnell

Port Macdonnell

Middle Point

Blackfellows Caves

Gerloffs Bay

Carpenters Rocks

Admella

Number 2 Rocks

South End

Rivolli Bay

Beachport

Nora Creina

Cape Jaffa

Spat

ial A

sses

smen

t Uni

t


Port Macdonnell

Middle Point

Blackfellows Caves

Gerloffs Bay

Carpenters Rocks

Admella

Number 2 Rocks

South End

Rivolli Bay

Beachport

Nora Creina

Cape Jaffa


21

Figure 3-5. The relationship between annual catch and (A) the catch cap (t) and (B) the ten-year average catch (t, 2005/06 to 2014/15) for each SAU in the SZ in 2015/16. (Ad, Admella; Bp, Beachport; BC, Blackfellows Caves; CJ, Cape Jaffa; CR, Carpenters Rocks; EPM, East Port MacDonnell; GB, Gerloffs Bay; MP, Middle Point; NC, Nora Creina; N2R, Number 2 Rocks; PM, Port MacDonnell; RB, Rivoli Bay; SE, Southend).

3.1.2.2 Temporal patterns in SAUs of high importance

Middle Point

Since 1979/80, ~26% of the blacklip catch from the SZ has been obtained from the Middle Point

SAU (range: 16–48%; Figure 3-4). Although variable among years, annual catches increased

steadily from


22

The estimated CPUE0.3 in the Middle Point SAU increased consistently (Linear regression, LR: r2

= 0.82, F1,30 = 138.8 P


23

Figure 3-7. (a) Frequency distributions of shell lengths in recent years and (b) percentage of large (>150 mm SL; black bars) blacklip in the commercial catch from Middle Point from 2001/02 (denoted 2001) to 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place since September 2013.

Figure 3-8. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Middle Point from 2002/03 (denoted 2002) to 2016/17. Surveys were not conducted in 2008/09, 2010/11, 2012/13 or 2013/14. Grey bars show total blacklip. Red and black bars show blacklip

13

4 m

m S

L)

-20

-10

0

10

20


24

then increased to 29 t in 1995/96 and remained above 15 t (range 15–30 t) until 2012/13 when

the catch was 29 t. From 2012/13, the catch declined (72%) to 8 t in 2015/16, which was the

lowest catch since 1991/92.

Catch rates (CPUE0.3) increased (93%) from 54 kg.hr-1 in 1994/95 to a peak of 104 kg.hr-1 in

2010/11. From 2010/11, catch rates declined (38%) to 63 kg.hr-1 in 2013/14. In 2015/16, the catch

rate of 73 kg.hr-1 was similar to that in 2014/15, remaining among the lowest values since 1996/97.

Interpreting size frequency distributions for Gerloffs Bay is difficult because, from 2013/14, the

MLL was increased from 110 mm to 120 mm. However, the most obvious trend is a reduced

proportion of large blacklip in commercial catches from 2012/13 (Figure 3-10).

For all size classes (i.e. total, legal-sized and sub-legal-sized), there were gradual reductions in

densities obtained from FI surveys with the estimate from 2014/15 the lowest on record (Figure

3-11). In 2016/17, total density increased slightly, reflecting increases in legal and sub-legal sized

densities. The percentage of large blacklip observed on surveys varied among seasons, but no

overall temporal trend was apparent.

Figure 3-9. Reported catch (tonnes, black bars) and CPUE0.3 (kg.hr-1, blue line) on blacklip in Gerloffs Bay between 1979/80 (denoted 1979) and 2015/16.

Fishing season

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

10

20

30

40

50

60

CPU

E (k

g.hr

-1)

20

40

60

80

100

120


25

Figure 3-10. Frequency distributions of shell lengths in recent years (a) and percentage of large (>150 mm SL) blacklip (b) in the commercial catch from Gerloffs Bay between 2001/02 (denoted 2001) and 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place since September 2013.

Figure 3-11. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Gerloffs Bay from 2002/03 (denoted 2002) to 2016/17. Surveys were not conducted in 2008/09, 2010/11, 2012/13, and 2013/14. Grey bars show total blacklip. Red and black bars show blacklip

15

0 m

m S

L)

0

2

4

6

8

10

12(a)

Size class (mm, SL)

115 120 125 130 135 140 145 150 155 160 165 170 175 180

Freq

uenc

y (%

)

0

10

20

30

4020152014201320122011

Fishing season

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

Den

sity

(aba

lone

.m-2

)

-2

0

2

% la

rge

blac

klip

(>13

4 m

m S

L)

-30

-20

-10

0

10

20

30


26

Figure 3-12), where after catches varied among years while gradually decreasing to the lowest

recorded value of 12 t in 2002/03. From 2002/03, annual catches gradually increased to 30 t in

2010/11 before declining (39%) to 18 t in 2014/15. From 2014/15, the catch increased (56%) to

28 t in 2015/16.

The CPUE0.3 on blacklip in Number 2 Rocks increased through time (LR: r2 = 0.68, F1,32 = 68.89;

P


27

Figure 3-13. Frequency distributions of shell lengths in recent years (a) and percentage of large (>150 mm SL) blacklip (b) in the commercial catch from Number 2 Rocks between 2001/02 (denoted 2001) and 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place since September 2013.

Figure 3-14. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Number Two Rocks in 2014/15 (denoted 2014) and 2016/17. No surveys was conducted in 2013/14. Grey bars show total blacklip. Red bars show blacklip 15

0 m

m S

L)

0

2

4

6

8

10

12

14

16(a)

Size class (mm, SL)

120 125 130 135 140 145 150 155 160 165 170 175 180

Freq

uenc

y (%

)

0

10

20

3020152014201320122011

Fishing season

2014

2015

2016

Den

sity

(aba

lone

.m-2

)

-2

-1

0

1

2

% la

rge

blac

klip

(>13

4 m

m S

L)

-40

-20

0

20

40


28

3.1.2.3 Temporal patterns in SAUs of medium importance

Rivoli Bay

Total annual catches of blackip from the Rivoli Bay SAU were small (~5 t.yr-1) compared to other

SAUs (Figure 3-4) prior to 1992/93 when 36 t was harvested (unrestricted fishing at a lower MLL

in FDA 3; Figure 3-15). Since 1992/93, catches have been variable among years (range 3-30 t).

Catches in 2000/01 and 2002/03, were above 25 t.y-1, then with the exception of 2006/07 (23 t),

generally declined to 2012/13 (13 t), where after they remained below 6 t. The catch of 4 t in

2015/16 was approximately one third of the long-term mean catch (1979/80–2014/15). CPUE0.3

was relatively stable (range 88–109 kg.hr-1) over 12 years from 1999/00 to 2011/12 when it was

102 kg.hr-1. From 2011/12, CPUE0.3 declined (15%) to 86 kg.hr-1 in 2012/13 (Figure 3-15). There

were insufficient data to calculate CPUE0.3 from 2013/14 to 2015/16.

Interpreting size frequency distributions for the Rivoli Bay SAU is difficult because, from 2013/14,

the MLL was reduced from 125 to 120 mm in mapcode 36B, in the area outside the historic FDA

3, and increased from 110 mm to 120 mm inside the historic FDA 3 (reflecting removal of FDAs).

However, the most obvious trend is a reduced proportion of large blacklip in commercial catches

in recent years, with none recorded in 2015/16 (Figure 3-16).

Total densities of blacklip obtained from FI surveys in Rivoli Bay were relatively stable from

2002/03 to 2011/12 (Figure 3-17), but high in 2006/07. Low densities of legal-sized and sub-legal-

sized blacklip occurred in 2012/13, immediately following a reported summer mortality (Mayfield

et al. 2013, 2014). Total densities increased from 2012/13 to 2016/17, reflecting an increase in

the densities of sub-legal-sized blacklip. The highest percentage of large blacklip estimated from

FI surveys was 13% in 2007/08. From 2007/08, the percentage of large blacklip declined

consistently to


29

From 2006/07, CPUE0.3 increased to a secondary peak of 102 kg.hr-1 in 2010/11, then declined

to 82 kg.hr-1 in 2012/13 and remained stable until 2015/16 when it was 81 kg.hr-1. This was the

lowest value since 1997/98. Declines in CPUE0.3 are evident in recent years for both mapcodes

in the Admella SAU (Appendix 3).

Interpreting size frequency distributions for the Admella SAU is difficult because, from 2013/14,

the MLL was reduced from 125 to 120 mm (Figure 3-16). Although the percentage of large blacklip

in commercial catches was variable among years (range


30

years prior to 2011/12. CPUE0.3 was 108 kg.hr-1 in 2012/13, and was relatively stable remaining

above 110 kg.hr-1 until 2015/16 when it was 109 kg.hr-1.

Interpreting size frequency distributions for the Port MacDonnell SAU is difficult because, from

2013/14, the MLL was reduced from 125 to 120 mm and there were insufficient data in 2015/16.

However, the most obvious trend is a decline in the proportion of large blacklip in commercial

catches from 2012/13, also reflected in the size frequency distribution (Figure 3-16).

3.1.2.4 Temporal patterns in SAUs of low importance

Across the low-importance SAUs, catches vary substantially among years. Nevertheless, for

several SAUs (South End, East Port MacDonnell, Cape Jaffa) the current catches are lower than

those observed historically. Exceptions are the Nora Creina and Blackfellowes Caves SAUs

where recent catches have increased. For the Beachport SAU, catches increased from 2–4 t.y-1

in the early 2000s to 10 t in 2008/09, 2009/10, and 2011/12 but declined to 3 t in 2015/16 (Figure

3-18). Insufficient data prevented estimation of CPUE0.3 in most years for these SAUs (Figure

3-18).


31

Figure 3-15. Reported catch (tonnes, black bars) and CPUE (kg.hr-1, blue line) on blacklip in the Rivoli Bay, Admella, Carpenters Rocks and Port MacDonnell SAUs between 1979/80 (denoted 1979) and 2015/16. Note scales on Y-axes vary among SAUs.

Carpenters Rocks

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

5

10

15

20

25

CPU

E (k

g.hr

-1)

20

40

60

80

100

120

Port MacDonnell

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

5

10

15

20

25

CPU

E (k

g.hr

-1)

50

60

70

80

90

100

110

120

130

Admella

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

5

10

15

20

CPU

E (k

g.hr

-1)

20

40

60

80

100

120

Rivoli Bay

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

10

20

30

40

CPU

E (k

g.hr

-1)

20

40

60

80

100

120

140


32

Figure 3-16. (a) Frequency distributions of shell lengths in recent years and (b) percentage of large (>150 mm SL; black bars) blacklip in the commercial catch from the Rivoli Bay, Admella, Carpenters Rocks and Port MacDonnell SAUs between 2001/02 (denoted 2001) and 2015/16. X-axis labels in (a) show upper limit of each size class. Dashed vertical line in (a) shows MLL in place since September 2013. Note scales on Y-axes vary among SAUs.* indicates insufficient data.

(b)

Fishing Season

2001 2003 2005 2007 2009 2011 2013 2015

% la

rge

blac

klip

(>15

0 m

m S

L)

0

2

4

6

8

10

12(a)

Size class (mm, SL)

115 120 125 130 135 140 145 150 155 160 165 170 175 180

Freq

uenc

y (%

)

0

10

20

30

40

5020152014201320122011

Rivoli Bay

(b)

Fishing Season

2001 2003 2005 2007 2009 2011 2013 2015

% la

rge

blac

klip

(>15

0 m

m S

L)

0

2

4

6

8

10

12

14

16

18(a)

Size class (mm, SL)

115 120 125 130 135 140 145 150 155 160 165 170 175 180

Freq

uenc

y (%

)

0

10

20

30

40

50

2014201320122011

(a)

Size class (mm, SL)

120 125 130 135 140 145 150 155 160 165 170 175 180

Freq

uenc

y (%

)

0

10

20

30

402015201420132012

(b)

Fishing Season

2001 2003 2005 2007 2009 2011 2013 2015

% la

rge

blac

klip

(>15

0 m

m S

L)

0

5

10

15

20

25

Admella

Carpenters Rocks

Port MacDonnell

**

* *

** **

Size class(mm, SL)

115 120 125 130 135 140 145 150 155 160 165 170 175 180

Freq

uenc

y (%

)

0

5

10

15

20

25

30201520142012

(b)

Fishing Season

2001 2003 2005 2007 2009 2011 2013 2015

% la

rge

blac

klip

(>15

0 m

m S

L)

0

2

4

6

8

10

12

14

16(a)

** ** * *

*

*

2015*


33

Figure 3-17. Density of blacklip (abalone.m-2; ± se) counted in transects during fishery-independent surveys at sites across Rivoli Bay from 2002/03 (denoted 2002) to 2016/17. Surveys were not conducted in 2008/09, 2010/11, and 2013/14. Grey bars show total blacklip. Red and black bars show blacklip 1

34 m

m S

L)

-15

-10

-5

0

5

10

15

Beachport

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

10

20C

PUE

(kg.

hr-1

)

20

40

60

80

100

120

Nora Creina

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

5

10

CPU

E (k

g.hr

-1)

20

40

60

80

100

Blackfellowes Caves

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

5

10

15

CPU

E (k

g.hr

-1)

20

40

60

80

100

120


1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

5

10

15

CPU

E (k

g.hr

-1)

40

50

60

70

80

90

100Cape Jaffa

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

1

2

3

4

5

CPU

E (k

g.hr

-1)

0

20

40

60

80

100

South End

1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

10

20

CPU

E (k

g.hr

-1)

40

60

80

100

120


34

3.1.3 Risk of overfishing in SAUs and zonal stock status

There were three high and four medium importance SAUs for blacklip in the SZ in 2015/16, with

the remaining SAUs being of low importance (Figure 3-2; Table 3-1). It was possible to determine

the risk of overfishing for five of the seven SAUs. The inability to estimate CPUE in the Rivoli Bay

SAU in 2015/16 due to insufficient data, and the lack of historical data for the Port MacDonnell

SAU during the reference period, resulted in the blacklip stocks in these SAUs being categorised

as uncertain (Table 3-1; Appendix 1). In addition, for the Number 2 Rocks SAU, the short time-

series of FI data meant that this high importance SAU could only be assessed with FD PIs (i.e.

three of a potential six PIs; Table 3-1). Summed PI scores ranged between -22 (Gerloffs Bay) and

+4 (Admella; Table 3-1). Gerloffs Bay and Middle Point SAUs were assigned to a 'red' (highest

risk), Number 2 Rocks and Carpenters Rocks to a ‘green’ (low risk), and Admella to a 'light blue'

(lowest risk) risk-of-overfishing category (Table 3-1). The catch-weighted zonal score was -0.65.

Under the harvest strategy, this score defines the status of the blacklip fishery in the SZ as ‘over fished’. (Table 3-1). It should be noted that the harvest strategy (PIRSA 2012) is currently under-review, with that review expected to be concluded by 31 December 2017.


35

Table 3-1. Outcome from application of the harvest strategy described in the Management Plan for the blacklip fishery in the SZ. Grey shading identifies the performance indicators and their respective scores.

Spatial assessment unit

%Contribution to mean total catch (SZ) over last 10 years (2006/07-

2015/16)

Importance

%Contribution to catch from high & medium SAU in 2015/16

CPUE %TACC %LargePre-

recruit density

Legal density

Mortality Combined PI score

Risk of overfishing

Catch-weighted

contribution to zonal score

Middle Point 21.0 High 30.9 0 0 -5 -4 -2 - ‐11 ‐2 ‐0.62Number 2 Rocks 16.6 High 32.7 0 2 0 ‐ ‐ ‐ 2 0 0.00Gerloffs Bay 14.5 High 9.2 ‐4 ‐3 ‐8 ‐4 ‐3 ‐ ‐22 ‐2 ‐0.18Admella 8.5 Medium 15.6 0 5 ‐1 ‐ ‐ ‐ 4 1 0.16Rivoli Bay 8.2 Medium - ND ‐3 ‐3 ‐ ‐ ‐ Uncertain Undefined ‐Carpenters Rocks 6.0 Medium 11.6 0 4 ‐5 ‐ ‐ ‐ ‐1 0 0.00Port MacDonnell 5.9 Medium - ND 8 ‐ ‐ ‐ ‐ Uncertain UndefinedBeachport 4.4 Low ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Not assessedSouth End 3.7 Low ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Not assessedBlackfellows Caves 3.3 Low ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Not assessedNora Creina 3.2 Low ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Not assessedCape Jaffa 0.4 Low ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Not assessedEast Port MacDonnell 0.2 Low ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Not assessedUnnassigned SZ 0.0 Low ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ Not assessed

Sum 96.0 100.0Zonal stock status -0.65


36

3.2 Greenlip

From 1968/69, when almost 19 t of greenlip was landed, greenlip catches in the SZ have generally

been small and did not exceed 6 t.yr-1 until 2010/11, increased to 7 t in 2010/11 and 2011/12

following an increase of the greenlip TACC to 7.2 t.yr-1 (Figure 3-19). In 2012/13 the catch was

6 t, then declined to 4 t thereafter. The TACC was reduced to 6 t in 2015/16, of which 4 t (66%)

was taken.

From 1979/80 to 2012/13, >70% of the catch was harvested from the Gerloffs Bay (40%), Rivoli

Bay (14%), East Port MacDonnell (11%) and Nora Creina SAUs (9%; Figure 3-19). Recently,

from 2012/13 to 2015/16, the relative contributions from these SAUs have changed with

decreasing contributions from Gerloffs Bay (22%) and East Port MacDonnell (1%) but increasing

contributions from Rivoli Bay (17%) and Nora Creina (20%). The high catches from the East Port

MacDonnell SAU during the mid–late 1990s had declined to negligible levels by 2005/06. Catches

from Gerloffs Bay were stable at 2–3 t from 2005/06 to 2012/13 but declined to 1 t from 2013/14

to 2015/16. In contrast, the catch from Rivoli Bay increased from 1 t in 2005/06 to 3 t in 2011/12

before declining again to one t in 2013/14 and 2014/15 with less than 0.5 t caught from this SAU

in 2015/16.

Figure 3-19. Reported catch (tonnes) of greenlip in the SZ and the Gerloffs Bay, Rivoli Bay, Nora Creina Bay and East Port MacDonnell SAUs from 1968/69 (denoted 1968) – 2015/16. The percentage of the greenlip catch harvested from the Gerloffs Bay SAU is also shown (red line).

% catch from Gerloffs Bay

Gerloffs Bay Rivoli Bay Nora Creina East Port Macdonnell Other SAUs

Fishing season

1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Cat

ch (t

)

0

5

10

15

20

% o

f cat

ch fr

om G

erlo

ffs B

ay S

AU

0

20

40

60

80

100


37

The highest proportion of large (>160 mm SL) greenlip in the commercial catch occurred in

2001/02 when it was 28% (Figure 3-20). From a secondary peak of 24% in 2009/10, the

proportion of large greenlip in catches declined to 7% in 2015/16 (Figure 3-20). Since the recent

peak of 24% in 2009/10, the percentage of large greenlip had declined to 7% by 2015/16. The

recent contraction of size frequency distributions is consistent with the trend in the proportion of

large greenlip in the commercial catch.

Estimates of total greenlip density at Ringwood Reef in the Rivoli Bay SAU generally increased

with the highest value in 2016/17 (Figure 3-21).

Figure 3-20. (a) Frequency distributions of shell lengths and (b) percentage of large (>160 mm SL) greenlip in the SZ commercial catch from 2001/02 (denoted 2001) to 2015/16. X-axis labels in panel (a) show the upper limit of each size class. Vertical red dashes represent MLL of 130 mm SL.

Figure 3-21. Density of greenlip (abalone.m-2; all length classes combined) from fishery-independent surveys in the Rivoli Bay SAU from 2002/03 to 2016/17. Surveys were not conducted in 2008/09, 2010/11, 2013/14, 2015/16.

(b)

Fishing Season

2001 2003 2005 2007 2009 2011 2013 2015

% la

rge

gree

nlip

(>16

0 m

m S

L)

0

10

20

30(a)

Size class (mm, SL)

125130135140145150155160165170175180185190195

Freq

uenc

y (%

)

0

5

10

15

20

2520152014201320122011

Fishing season

2002 2004 2006 2008 2010 2012 2014 2016

Den

sity

(aba

lone

.m-2

)

0.0

0.1

0.2

0.3


38

4 GENERAL DISCUSSION

4.1 Current status of blacklip and greenlip in the Southern Zone

4.1.1 Blacklip

From 1979/80 to 2011/12, the fishery for blacklip was characterised by (1) high, stable total

catches; (2) declining effort after 1992/93; (3) increasing CPUE; (4) stable distribution of catch

among SAUs; (5) generally stable length-frequency distributions after 2002/03; and (6) consistent

survey estimates of sub-legal-sized and legal-sized density. These patterns were reflected in the

zonal stock status classifications from the harvest strategy of ‘lightly fished’ in 2011/12 and

’underfished’ in 2012/13. During this period, the fishery was also categorised as ‘sustainable’

under the NFSRF (Flood et al. 2014; Stewardson et al. 2016).

In 2013/14 and 2014/15, the SZ blacklip fishery was classified as ‘transitional depleting’ under the

NFSRF (Mayfield et al. 2015; Flood et al. 2014; Stewardson et al. 2016) due to the failure of the

TACC to be harvested in 2013/14 (83% was landed) and 2014/15 (89% was landed), declining

catch rates across the zone and in numerous key SAUs, lower proportions of large blacklip in

commercial catch samples and from FI surveys, and reductions in the densities of legal-sized and

sub-legal-sized blacklip estimated from surveys. In response, the TACC for blacklip in the SZ was

reduced from 151.5 t to 126 t in 2015/16 (a reduction of 16.8%).

Despite the reduced TACC in 2015/16, there is evidence that the SZ blacklip fishery remains in a

weak position, including: (1) continuing decline in catches from high importance SAUs (50% in

2014/15 and 2015/16, compared to a long-term average of 58%); (2) rapid declines in catch from

traditional fishing grounds in the Middle Point and Gerloffs Bay SAUs (High Importance) replaced

by increases from Number 2 Rocks (High Importance), and Admella, Carpenters Rocks and

notably Port MacDonnell SAUs (Medium Importance); (3) redistribution of catches within the

Middle Point SAU with a reduction in the contribution from mapcode 40A resulting in almost all

the 2015/16 catch being taken from two of three mapcodes (Appendix 3), despite a decrease in

the MLL in mapcode 40A from 2013/14 (from 125 to 120 mm SL); (4) steep decline in CPUE for

the Middle Point SAU, and all three mapcodes (especially in 40A where the MLL was reduced)

comprising this SAU, over four years (2010/11 to 2015/16), and in the Gerloffs Bay SAU from

2011/12 to 2013/14 with subsequent low recent values; (5) no increase in CPUE following

reduction in the MLL from 125 to 120 mm in the Admella SAU; (6) proportions of large blacklip in

commercial catches from many SAUs remained low or declined, though small increase in the


39

Middle Point and Number 2 Rocks SAUs were noted; and (7) recent FI estimates of sub-legal and

legal-sized blacklip densities from FI surveys were relatively low in two of three high importance

SAUs (Middle Point, Gerloffs Bay) in 2014/15 and 2016/17. Application of the harvest strategy in

the Management Plan (PIRSA 2012) resulted in an ‘over fished’ stock status for blacklip in the SZ

in 2015/16. The stability in abundance implied by the stable zonal CPUE from 2012/13 to 2015/16

does not account for the likely increase in effective fishing effort over this period.

Collectively, the available evidence suggests that the SZ blacklip fishery is in a weak position.

Fishing pressure is too high and is moving the stock in the direction of becoming recruitment

overfished. Consequently, the SZ blacklip fishery remains classified as ‘transitional-depleting’ under the NFSRF (Flood et al. 2014; Stewardson et al. 2016), which was the same as the

classification for 2013/14 and 2014/15. Fishing pressure is unlikely to be the only contributing

factor to the observed declines. The blacklip mortality associated with anomalously high water

temperatures from January to May in 2013 (Vilchis et al. 2005; Mayfield et al. 2011; Government

of South Australia 2013), while documented but unquantified (Mayfield et al. 2013), has likely also

contributed to the decline in harvestable biomass of blacklip in the SZ.

4.1.2 Greenlip

The low current and historical catches, and limited data, prevent unambiguous assessment of the

current status of greenlip in the SZ. Consequently, under the NFSRF (Flood et al. 2014;

Stewardson et al. 2016), the stock status of greenlip in the SZ is classified as 'undefined'. Decisions on future TACCs are likely to continue to rely heavily on input from other sources such

as divers and licence holders in the fishery.

4.2 Information, data gaps and uncertainty in the assessment

Assessment of blacklip stock status is supported by numerous data including: (1) a well-

documented history of the management of the fishery; (2) extensive biological data (see Mayfield

and Saunders 2008); (3) spatially resolved catch, effort and commercial size data; and (4) FI

survey data on blacklip density and size frequencies for three high importance SAUs, i.e. Middle

Point, Number 2 Rocks and Gerloffs Bay. These data facilitated both the formal analysis of the

fishery’s performance and stock status based on the harvest strategy described in the Fishery

Management Plan for the commercial Abalone Fishery (PIRSA 2012) and a weight-of-evidence

analysis under the NFSRF (Flood et al. 2014; Stewardson et al. 2016) to determine stock status.


40

There were however several limitations to undertaking this assessment. Firstly, FI survey data for

Number 2 Rocks were limited to 2014/15 and 2015/16. This problem will be overcome as the

time-series of data increases with future surveys. Second, this assessment relied on estimates of

catch-rates (CPUE) based on commercial data to provide an index of relative abundance for

blacklip. Catch-rate can be influenced by numerous factors unrelated to abalone abundance

including: changes to MLLs (see Mayfield et al. 2015); market demands for particular product

types (e.g. larger or smaller abalone – although this has not been documented in the SZ); changes

in diver behaviour; increasing fishing efficiency; and variable weather conditions (e.g. wind, swell,

turbidity, access to traditional grounds). While the degree to which extrinsic factors may have

influenced CPUE in recent years remains undetermined, we note that (1) decreases in CPUE in

abalone fisheries can be considered a reliable indicator in abalone abundance (Tarbath and

Gardner 2011); and (2) reductions in CPUE likely underestimate declines in abundance because

catch rates in dive fisheries are typically hyperstable (Dowling et al. 2004) and recent changes in

fishing practice over the last 3-5 years – from vessel anchoring to live boating that would have

raised fishing efficiency – have not been taken into account in this assessment.

Third, several decision rules were used to provide a sub-set of the FD data, primarily prior to

estimating CPUE and the proportion of large blacklip in the commercial catch. This approach was

adopted because both blacklip and greenlip can be harvested, but effort within a fishing day is

not separated between species and followed a comprehensive comparison of the current,

previous and a range of alternate decision rules to estimate CPUE (Burch et al. 2011). In this

assessment we also compared blacklip catch rates on days with and without greenlip catches for

the whole SZ that confirmed mixed species fishing in the SZ has little influence on CPUE

estimation – primarily because the TACC and daily catches are dominated by blacklip.

Finally, several limitations of the relatively new harvest strategy, including over-optimistic

outcomes, have been identified (Mayfield et al. 2014; Stobart et al. 2014). Due to a lack of data,

it was not possible to score CPUE using the harvest strategy in two medium importance SAUs –

Rivoli Bay and Port Mac

Documents

Assessment of the Southern Zone Abalone · 2017. 12. 11. · Assessment of the Southern Zone Abalone (Haliotis rubra and H. laevigata) Fishery in 2015/16 G.Ferguson, S. Mayfield,