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Stock Status Overview
|Tasmania||Tasmanian Greenlip Abalone Fishery||TGAF||Transitional-depleting||CPUE|
- Tasmanian Greenlip Abalone Fishery (TAS)
Greenlip Abalone is distributed across southern mainland Australia and northern Tasmania. The biological stock structure of Greenlip Abalone has recently been examined1,2. Genetic evidence has confirmed that Greenlip Abalone comprise numerous independent biological stocks, but at a spatially broader scale than the biological stock structure evident for Blacklip Abalone1–3. There are many biological stocks across Tasmania, Victoria, South Australia and Western Australia. Given the large number of biological stocks, it is not practical to assess each separately.
Here, assessment of stock status is presented at the management unit level—Western Australian Area 2 Fishery, Western Australian Area 3 Fishery, Victorian Central Zone Fishery, Victorian Western Zone Fishery, Tasmanian Greenlip Abalone Fishery, South Australian Western Zone Fishery, South Australian Central Zone Fishery and South Australian Southern Zone Fishery.
Undertaking assessments of abalone stock status is complicated by several factors, including: spatial variation in levels of depletion within management units ; changes to management unit boundaries and size limits; absence of a performance indicator and reference points above or below which the fishery would be defined as sustainable or recruitment overfished; changes in fishing power, which impede comparisons of current and historical catch per unit effort (CPUE); the multitude of factors that affect the effort component of CPUE; the degree to which CPUE reflects abalone abundance. The methods of assessing stock status can also vary among jurisdictions and management units.
Tasmanian Greenlip Abalone Fishery
The Tasmanian abalone fishery has been quota managed with an annual TACC since 1985. Since 2000, separate TACCs for Greenlip Abalone and Blacklip Abalone have been implemented, with catch caps within the Greenlip TACC applied to four regions within the Greenlip zone. Size Limits vary with a legal minimum length (LML) of 132 mm, 145 mm or 150 mm depending on growth rates, size at maturity and maximum size of populations in different regions. An annual fishery assessment is conducted using fishery-dependent CPUE data, and until 2014 the TACC was determined by an ad-hoc approach using trends in CPUE and industry perceptions on the state of the resource. In the 2012 and 2014 Status of Australian Fish Stocks editions, this fishery was classified as undefined due to the complexities of reporting and apportioning of effort, and hence understanding CPUE, in this mixed species fishery. The fishery-dependent data time series has since been reviewed and revised and a formal process for assigning effort in mixed species fishing events established12, enabling the development of separate CPUE indices for Greenlip and Blacklip Abalone.
In 2014–15, an empirical harvest strategy (HS) was developed12,13 and tested by Management Strategy Evaluation (MSE)14–16. This HS was applied to the 2015 annual fishery assessment12. The HS assesses the fishery performance against target reference points for three performance measures (PM) derived from SCPUE data: 1) current CPUE relative to an agreed target (55th percentile of the annual standardised mean CPUE within the reference period); 2) the 4-year gradient of CPUE (target gradient is zero); and 3) the percent change in SCPUE in the past year (target change is zero). The reference period for the 2015 assessment spans fishery data between 1992 and 2015.A scoring function is applied to the three PMs, resulting in a score between zero and 10, where five is the target score and zero and 10 are the zone-wide lowest and highest values for that PM within the reference period. Weightings are applied to the three PMs 05:0.25:02.5 to provide a combined final score used in the Control Rule. The HS is applied individually to each statistical reporting block, and a zone score is obtained from the mean block score weighted by block catch. The zone target CPUE PM score is used as a proxy for biomass and the zone gradient CPUE PM score is used as a proxy for fishing mortality, F. A target CPUE score of one is the limit reference point (LRP) defining the boundary between recruitment overfished and transitional–depleting for all Tasmanian management units. This LRP is typically five per cent above the lowest SCPUE observed within the zone during the reference period. A negative zone gradient score gives evidence that fishing mortality is increasing and the magnitude of the gradient provides some information on the magnitude of F. In order to emulate a normal phase plot, five is subtracted from the gradient four PM score to provide a range of negative five–positive five, where the target reference point is zero, and defines the boundary between sustainable and transitional–depleting classifications, but also between transitional–recovering and recruitment overfished. The combination of a negative CPUE gradient and near record low CPUE score represents a cautious proxy for the true recruitment overfished reference point. No reporting blocks have collapsed within the reference period, providing a degree of certainty that the LRP will prevent stock collapse, which is supported by MSE testing of the HS12.
The TACC for the Tasmanian Greenlip Abalone Fishery has been stable at around 140 t since 2000, with only minor variation in the proportion of the TACC harvested from each of the four regions (King Island, North West, North East and Furneaux). In 2015, the zone-wide catch-weighted block mean SCPUEcw was 62.6 kg per hour, compared to 60.4 kg per hour in 1999, prior to the introduction of separate Greenlip Abalone TACC. The regional SCPUE is close to the target SCPUE in two of the four regions; the Furneaux Group region is above the target and the King Island region is below the target The current North West SCPUE of 72 kg per hour is close to the CPUE target (75 kg per hour), but has been declining rapidly since 2012 (91 kg per hour). Half of the catch cap in this region is taken from an area where the LML is set at 132 mm. With an increasing beach price offered for larger Greenlip Abalone, selective fishing for larger animals has become common place, with a negative effect on catch rates (greater handling and search time), potentially distorting SCPUE trends in this region. The King Island SCPUE has been declining for several years, although in 2015 SCPUE is above 50 kg per hour and moving towards the CPUE target of 65 kg per hour. King Island has the largest LML (150 mm) and assumed to provide greater protection of spawning biomass. Changes from a winter to late-summer (lower weight/length) fishing season in recent years and increased selective fishing are thought to have had more influence over the SCPUE trend and HS outcomes than actual changes in biomass12. However, until these factors are included in the CPUE standardisation, as a precautionary approach this stock is considered to be declining from a sustainable position. The zone-wide proxy for biomass is 4.1 and above the LRP, and the zone-wide proxy for F is negative 1.2 and below the TRP for sustainability.
The above evidence from the Tasmanian commercial Greenlip Abalone fishery indicates that the biomass of this stock is not recruitment overfished. The above evidence indicates that the current level of fishing pressure is likely to cause the stock to become recruitment overfished.
On the basis of the evidence provided above, the Tasmanian Greenlip Abalone Fishery management unit is classified as a transitional–depleting stock.
Greenlip Abalone biology16,18
|Species||Longevity / Maximum Size||Maturity (50 per cent)|
|Greenlip Abalone||20 years; 200 mm SL||3–5 years; 70-120 mm SL|
Distribution of reported commercial catch of Greenlip Abalone
|Total allowable catch|
|58 in TGAF|
- Tasmanian Greenlip Abalone Fishery (TAS)
|Commercial||143.97t in TGAF|
- Tasmanian Greenlip Abalone Fishery (TAS)
a Victoria – Indigenous (catch) In Victoria, regulations for managing recreational fishing are also applied to fishing activities by Indigenous people. Recognised Traditional Owners (groups that hold native title or have agreements under the Traditional Owner Settlement Act 2010 [Vic]) are exempt (subject to conditions) from the requirement to hold a recreational fishing licence, and can apply for permits under the Fisheries Act 1995 (Vic) that authorise customary fishing (e.g. different catch and size limits, or equipment). The Indigenous category in Table 3 refers to customary fishing undertaken by recognised Traditional Owners. In 2012–13, there were no applications for customary fishing permits to access Greenlip Abalone.
b Indigenous Subject to the defence that applies under Section 211 of the Native Title Act 1993 (Cth), and the exemption from a requirement to hold a recreational fishing licence, the non-commercial take by indigenous fishers is covered by the same arrangements as that for recreational fishing.
Commercial catch of Greenlip Abalone
Effects of fishing on the marine environment
- Because Greenlip Abalone is hand selected by commercial divers operating from vessels that seldom anchor, the fishery has limited direct physical impact on the environment. There is also substantial evidence that the ecosystem effects of removing abalone are minimal23–25.
Environmental effects on Greenlip Abalone
- Southward and westward strengthening of the warm East Australian Current into the relatively cold inshore waters in Tasmania has changed near-shore community structure and productivity, primarily through expansion of the range of the urchin Centrostephanus rodgersii from New South Wales to Tasmania26–28. This has resulted in localised depletions of abalone populations and a reduction in the habitat available for abalone29,30.
Miller, KJ, Mundy, CN and Mayfield, S 2014, Molecular genetics to inform spatial management in benthic invertebrate fisheries: a case study using the Australian Greenlip Abalone, Molecular Ecology, 23: 4958–4975.
Mayfield, S, Miller, KJ and Mundy, CM 2014, Towards understanding Greenlip Abalone population structure, Final report to the Fisheries Research and Development Corporation, project 2010/013, South Australia Research and Development Institute, Adelaide.
Miller, KJ, Maynard, BT and Mundy, CN 2009, Genetic diversity and gene flow in collapsed and healthy abalone fisheries, Molecular Ecology, 18: 200–211.
- 4 Department of Fisheries, Western Australia (in prep). Abalone resource of Western Australia harvest strategy 2016–2021, Fisheries Management Paper. DOF WA, Perth.
- 5 Hart, A, Strain, L, Hesp, A, Fisher, E, Webster, F, Brand-Gardner, S and Walter, S (in prep), Marine Stewardship Council full assessment report, Western Australian Abalone Managed Fishery, Department of Fisheries, Western Australia, Perth.
Hart, AM, Fabris, F, Brown, J and Caputi, N 2013, Biology, history and assessment of Western Australian abalone fisheries. Fisheries Research Report No. 241. Department of Fisheries, Western Australia, Perth.
- 7 Victorian Department of Environment and Primary Industries 2002, Victorian Abalone Fishery management plan, Fisheries Victoria, Melbourne.
- 8 Gorfine, HK and Dixon, D (ed.s) 1999, Greenlip Abalone—1998, compiled by Abalone Stock Assessment Group, Fisheries Victoria assessment report 26, Marine and Freshwater Resources Institute, Queenscliff.
Victorian Government 2013,Victoria Government Gazette, 28 March 2013
- 10 Gorfine, HK 2007, Assessment of abalone fishing potential in the Julia Bank region of western Victoria, Primary Industries Research Victoria–Marine and Freshwater Systems internal report 62, PIRVic, Queenscliff.
- 11 Prince, J 2008, Analysis of Greenlip Abalone sampling from Minerva and Hospital Reef, Portland, 10–11 May, 2008, unpublished report to the Western Abalone Divers Association, 13 June 2008.
- 12 Mundy, C and Jones, HJ (in prep), Tasmanian Abalone Fishery assessment 2015. Institute for Marine and Antarctic Studies Report, University of Tasmania, Hobart.
- 13 Mundy, C and Jones, H 2016, Multi-criteria decision analysis based harvest strategy for the Tasmanian abalone fishery, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart.
- 14 Buxton, CD, Cartwright, I, Dichmont, CM, Mayfield, S and Plaganyi-Lloyd, E 2015, Review of the harvest strategy and MCDA process for the Tasmanian Abalone Fishery. Institute for Marine and Antarctic Studies, University of Tasmania, Hobart.
Haddon, M, Mayfield, S, Helidoniotis, F, Chick, R and Mundy, C 2014, Identification and evaluation of performance indicators for abalone fisheries, Fisheries Research and Development Corporation project 2007/020, Commonwealth Scientific and Industrial Research Organisation, Hobart.
- 16 Haddon, M and Mundy, C 2016, Testing abalone empirical harvest strategies, for setting TACs and associated LMLs, that include the use of novel spatially explicit performance measures. Commonwealth Scientific and Industrial Research Organisation, Oceans and Atmosphere, Hobart.
Primary Industries and Regions South Australia 2012, Management plan for the South Australian commercial abalone fishery, September 2012, Government of South Australia, Adelaide.
- 18 Burnell, O, Mayfield, S, Ferguson, G and Carroll, J 2016, Central Zone Abalone (Haliotis laevigata and H. rubra) Fishery, Fishery Assessment Report for Primary Industries and Regions South Australia, Fisheries and Aquaculture, SARDI Publication No. F2007/000611-7, SARDI Research Report Series No. 927, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
Stobart, B and Mayfield, S 2016a, Assessment of the Western Zone Greenlip Abalone (Haliotis laevigata) Fishery in 2015. Fishery Stock Assessment Report to Primary Industries and Regions South Australia Fisheries and Aquaculture, SARDI Publication No. F2015/000373-2. SARDI Research Report Series No. 920, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
Stobart, B and Mayfield, S 2016b, Status of the Western Zone Blacklip Abalone (Haliotis rubra) fishery in 2015, Report for Primary Industries and Regions South Australia Fisheries and Aquaculture, SARDI Publication No. F2014/000361-2. SARDI Research Report Series No. 918, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
Dowling, NA, Hall, SJ and McGarvey, R 2004, Assessing population sustainability and response to fishing in terms of aggregation structure for Greenlip Abalone (Haliotis laevigata) fishery management, Canadian Journal of Fisheries and Aquatic Sciences, 61: 247–259.
Shepherd, SA and Rodda, KR 2001, Sustainability demands vigilance: Evidence for serial decline of the Greenlip Abalone Fishery and a review of management, Journal of Shellfish Research, 20: 829–841.
Tarbath, D, Mundy, C and Gardner, C 2014, Tasmanian Abalone Fishery assessment 2013, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart.
Ferguson, G and Mayfield, S 2016, Status of the Southern Zone blacklip (Haliotis rubra) and greenlip (H. laevigata) abalone fisheries in 2014–15, Report for Primary Industries and Regions South Australia, Fisheries and Aquaculture, SARDI Publication No. F2014/000359-2. SARDI Research Report Series No. 902, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
Hamer, P, Jenkins, G, Womersley, B and Mills, K 2010, Understanding the ecological role of abalone in the reef ecosystem of Victoria, Fisheries Research and Development Corporation, project 2006/040, Marine and Freshwater Resources Institute, Queenscliff.
Jenkins, GP 2004, The ecosystem effects of abalone fishing: A review, Marine and Freshwater Research, 55: 545–552.
Valentine, JP, Tarbath, DB, Frusher, SD, Mundy, CN and Buxton, CD 2010, Limited evidence for ecosystem-level change on reefs exposed to Haliotis rubra (Blacklip Abalone) exploitation, Austral Ecology, 35: 806–817.
Ling, SD 2008, Range expansion of a habitat-modifying species leads to loss of taxonomic diversity: a new and impoverished reef state, Oecologia, 156: 883–894.
Ling, SD, Johnson, CR, Ridgway, K, Hobday, AJ and Haddon, M 2009, Climate driven range extension of a sea urchin: Inferring future trends by analysis of recent population dynamics, Global Change Biology 15: 719–731.
Ridgway, KR 2007, Long-term trend and decadal variability of the southward penetration of the East Australian Current, Geophysical Research Letters, 34: L13613.