*

Of eight Greenlip Abalone stocks defined by management area, three are undefined (SA Southern Zone, VIC Central Zone, VIC Western Zone), three are depleting (TAS Greenlip Abalone Fishery, SA Central Zone and SA Western Zone), one is depleted (WA Area 3 Fishery), and one is recovering (WA Area 2 Fishery).

Greenlip Abalone is distributed across southern mainland Australia and northern Tasmania. The biological stock structure of Greenlip Abalone has recently been examined [Mayfield et al. 2014, Miller et al. 2014]. 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 Abalone [Miller et al. 2009, Mayfield et al. 2014, Miller et al. 2014]. There are many biological stocks across Western Australia, Tasmania, Victoria and South Australia. Given the large number of biological stocks, it is not practical to assess each separately, and they are neither fished nor managed at that separate biological stock level.

Here, assessment of stock status is presented at the management unit level—South Australia Central Zone Fishery, South Australia Southern Zone Fishery and South Australia Western Zone Fishery (South Australia); Tasmania Greenlip Abalone Fishery (Tasmania); Victoria Central Zone Fishery, Victoria Western Zone Fishery (Victoria), Western Australia Area 2 Fishery, Western Australia Area 3 Fishery (Western Australia).

Western Australia Area 2 Fishery

Greenlip Abalone catches in the Western Australia Area 2 and Area 3 Fisheries are controlled by a total allowable commercial catch (TACC), set annually in accordance with a harvest control rule defined in the Abalone Resource of Western Australia Harvest Strategy 2021–26 [DPIRD 2023]. The harvest control rule uses the annual standardised catch per unit effort (SCPUE) as the key performance indicator (PI) against specified limit, threshold and target reference levels. The reference levels for the Western Australia Area 2 and Area 3 Fisheries have recently been updated based on estimates of biomass relative to the levels associated with Maximum Sustainable Yield (MSY), i.e., BMSY. The target, threshold and limit reference levels in each management area are now equivalent to the SCPUE corresponding to the estimated biomass at 1.2BMSY, BMSY and 0.5BMSY, respectively [DPIRD 2023]. The Western Australia Area 2 Fishery (WAA2F) is defined as depleted if the PI is below the limit reference level.

In the WAA2F, the catch of Greenlip Abalone for the 2022 season was 16 t (99% of TACC). Between 2014 and 2020 the annual catches declined by 60 t due to reductions in TACC, however the TACC and catch has remained constant for the last 2 seasons. The annual SCPUE for Greenlip Abalone oscillated between the threshold and limit reference levels from 1992 to 2014, with a declining trend from 2010 to below the limit reference level in 2015. This decline in SCPUE arrested between 2015 and 2020 (below limit reference level), and the SCPUE has increased over the last two seasons to above the limit reference level in 2021 and 2022. The arrested decline and subsequent increase in SCPUE indicates the stock has responded to the reductions in catch between 2014 and 2020. Sub-area analysis of raw catch rate, average meat weight per individual and length-frequency distributions from commercial catch sampling are consistent with the decline in the SCPUE trend from 2010 to 2015 [Hart et al. 2013, Hart et al. 2017]. Recent (post-2015) SCPUE stabilisation and increase is consistent with trends in nominal catch rates for WAA2F and all five sub-areas. There has also been evidence of an increase in meat weight of individual animals over the last seven seasons, but to varying degrees across the sub-areas. 

The fishery has a legal minimum length of 145 mm, which allows 2–5 years of spawning to occur before recruitment to the fishery. Above-average water temperatures since 2011 (extreme marine heatwave in the 2010–11 summer) are likely to have had negative effects on abalone growth or recruitment, but evidence for this type of impact needs to be assessed further.

The above evidence indicates that the biomass of this stock is recovering from a period of being depleted where recruitment was likely to be impaired. For the period 2010–2015 the biomass declined, and between 2015 and 2020 the stock was considered to be recruitment impaired. Under the Harvest Strategy, management action was implemented in the WAA2F to bring the TACC in line with the harvest control rule. This resulted in the TACC being reduced over the 2015 to 2020 period to 20 per cent of long-term, commercial sustainable harvest level (16 t whole weight) [DPIRD 2023]. The reductions in TACC have reduced the fishing mortality and based on the increases in SCPUE and meat weight in recent seasons it suggests that the WAA2F is recovering. The above evidence indicates that the biomass of this stock was likely to be depleted and that recruitment was likely to be impaired. However, for the period 2019 to 2023 these indicators suggest a recovering stock and the current level of fishing mortality should allow the stock to continue to recover from previous recuitment imparied state.

Based on the evidence provided above, the Western Australia Area 2 Fishery management unit is classified as a recovering stock.

Western Australia Area 3 Fishery

Greenlip Abalone catches in the Western Australia Area 3 Fishery (WAA3F) are managed by the same total allowable commercial catch (TACC) setting process as described above for the Western Australia Area 2 Abalone Fishery, and defined in the Abalone Resource of Western Australia Harvest Strategy 2021–26 [DPIRD 2023].

In the WAA3F, the catch of Greenlip Abalone for the 2022 season was 10.7 t (100% of TACC). Between 2013 and 2019 the annual catches declined by 82 t due to reductions in TACC, however the TACC and catch has remained constant for the last 2 seasons. The annual standardised catch per unit effort (SCPUE) for Greenlip Abalone exhibited a declining trend from above the threshold reference level in 2000, towards the limit in 2005. A steady increase in annual SCPUE then occurred until 2010, whereafter it declined until 2018 and went below the limit reference level from 2015. The reference levels were updated in 2021 as part of the Harvest Strategy review and based on estimates of biomass relative to the levels associated with Maximum Sustainable Yield (MSY), i.e., BMSY. [DPIRD 2023]. In 2019, the major component of WAA3F (the Augusta sub-area provides 54% of annual commercial catch in WAA3F) was closed to commercial fishing and the TACC (remaining open areas) reduced to 11.8% of the long-term, commercial sustainable harvest level (10.7 t whole weight). The SCPUE increased over the next two seasons to the limit reference level but declined slightly in 2021. However, this only represents the open regions of WAA3F.

Analysis of raw catch rate, average meat weight per individual and length-frequency distributions from commercial catch sampling support evidence of the declining trend in SCPUE between 2010 and 2018 [Hart et al. 2013, Hart et al. 2017]. However, steady raw catch rates and increases in meat weight per individual have occured over the last four to five seasons. Fishery-independent surveys in the Augusta sub-area indicate the total density of Greenlip Abalone has been at low levels for the last eight years. Densities of juvenile animals (4–8 cm shell length) increased in 2018 after four years of record low values (2014 to 2017) but have declined slightly since 2018 [Hart et al. 2017]. The fishery has a legal minimum length of 150 mm which allows 3–6 years of spawning to occur before recruitment to the fishery. Above-average water temperatures since 2011 (extreme marine heatwave in the 2010–11 summer) are likely to have had negative effects on abalone growth or recruitment, but evidence for this type of impact needs to be assessed further.

Under the previous Harvest Strategy [Department of Fisheries 2017], management action was implemented in the WAA3F to bring the TACC in line with the harvest control rule in 2017. However, since 2017, the TACC has been reduced further, until in 2019 a reduction of quota by 50% was achieved through the closure of the Augusta sub-area to commercial fishing for Greenlip Abalone. The 2019 TACC reduction to 11.8% of the long-term sustainable harvest level (10.7 t whole weight) was predicated on; (1) the SCPUE being below the limit reference level; (2) the Harvest Control Rule outcome; (3) additional stock indicators exhibiting a declining trend; (4) Augusta sub-area SCPUE continued decline; and (5) fishery-independent surveys in the Augusta sub-area indicating that total, juvenile and legal-sized density are all at, or near, historical low levels. The TACC has remained at this level for the last four seasons (Augusta sub-area closed) and while the SCPUE has increased it was not above the limit reference level in 2022.

The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely impaired. Current fishing mortality is constrained by management to a level that should allow the stock to recover from its recruitment impaired state; however measurable improvements are yet to be detected.

Based on the evidence provided above, the Western Australia Area 3 Fishery management unit is classified as a depleted stock.

Greenlip Abalone biology [Burnell et al. 2016, Haddon and Mundy 2016, Hart et al. 2017]

Distribution of reported commercial catch of Greenlip Abalone

Victoria – Indigenous (Management Methods) A person who identifies as Aboriginal or Torres Strait Islander is exempt from the need to obtain a Victorian recreational fishing licence, provided they comply with all other rules that apply to recreational fishers, including rules on equipment, catch limits, size limits and restricted areas. Traditional (non-commercial) fishing activities that are carried out by members of a traditional owner group entity under an agreement pursuant to Victoria’s Traditional Owner Settlement Act 2010 are also exempt from the need to hold a recreational fishing licence, subject to any conditions outlined in the agreement. Native title holders are also exempt from the need to obtain a recreational fishing licence under the provisions of the Commonwealth’s Native Title Act 1993.

Commonwealth – Indigenous (Management Methods) 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.

Western Australia - Recreational (Catch Volume) [Smallwood et al. 2023]

Commercial catch of Greenlip Abalone - note confidential catch not shown.

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