*

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).

South Australia Central Zone Fishery

The most recent assessment report for the South Australia Central Zone Fishery (SACZF) was completed in 2023 and reported to the end of the 2022 fishing season (calendar year) [Burnell 2023]. The primary measures for biomass and fishing mortality are catch-per-unit-effort (CPUE) and fishery- independent survey (FIS) of legal-sized density [PIRSA 2021]. There were several key limitations to this assessment, including (1) the use of CPUE as a key index of legal-sized abalone abundance and (2) the absence of FIS for most spatial assessment units (SAUs). A key assumption for CPUE is that it represents relative abundance of the fishable stock and that it can detect changes in relative abundance of the stock (Tarbath et al. 2005). However, CPUE can be influenced by numerous factors unrelated to abalone abundance (Stobart et al. 2017), is often hyperstable and commonly viewed as a (upwardly) biased index of relative abundance (Stobart et al. 2017). Except for Tiparra Reef, the FIS are available for a relatively short time period and cover spatially discreet areas. Collectively, these increase the uncertainty of the assessment. 

The South Australian HS assesses the fishery performance against target reference points for two equally weighted performance measures (PM), CPUE and legal density (where available) of abalone from fishery independent surveys. A scoring function is applied to these PM’s based on agreed reference periods described in the management plan, with scoring based on limit (score 0) and target (score 5) reference points within a score range of 0 - 10 (PIRSA 2021). Performance is scored at a spatial assessment unit (SAU) scale designed to represent “approximate biological populations”, the SAU scores are catch weighted and aggregated to provide a zone score that forms the basis for setting total allowable catch for the following year. The zone score also enables determination of stock status that is based on trigger reference points for biomass (zone score used as a proxy) and fishing mortality (zone score trend used as a proxy). 

The total commercial catch for Greenlip Abalone in the SACZF declined from 46 to 23 tonnes (t) (meat weight) between 2019 and 2022, a reduction of more than 50% from the average catch of 47 t over the preceding three decades. This recent decline was a result of voluntary under catch by industry associated with concern for Greenlip Abalone stocks and subsequent total allowable commercial catch (TACC) reductions [Burnell and Mayfield 2023, Burnell 2023]. 

The CPUE for Greenlip Abalone in the SACZF remained relatively stable between 1985 and 1999 (averaging 21 kg per hour) and then increased rapidly, reaching a peak of 31 kg per hour in 2001, associated with a large increase in abundance at one of the key fishing grounds, Tiparra Reef. From 2005, CPUE decreased steadily reaching a low of 19 kg per hour in 2021. In 2022, CPUE increased to 20 kg per hour, but remains among the lowest values observed since the late 1990s. Despite this current low in CPUE, 5 of the 6 SAUs in 2022 had a CPUE score between 3.9 and 5 in the HS, indicating estimates are within, or slightly below, target ranges [PIRSA 2021]. Similarly, the most recent estimates of legal-sized density from the fishery-independent surveys in the two key SAUs (Tiparra Reef and West Yorke Peninsula) had scores of 5.0 and 4.6 in the HS, respectively, indicating Greenlip Abalone density was within, or slightly below, target ranges. The sub-legal-sized density of Greenlip Abalone in 2021 at a key fishing ground - Tiparra Reef - remained below all estimates recorded in the 1990s and 2000s, but had increased by 60% from the lowest value recorded in 2015. 

Application of the harvest strategy [PIRSA 2021] resulted in a zone score of 4.5 that, in combination with the zone trend score of 5.0 (reflecting a stable trend), define the stock status for Greenlip Abalone in the CZ in 2022 as ‘sustainable’. The status is sustainable because the zone score (i.e. biomass proxy) is above the limit reference point of a score of 1, and the zone trend score (i.e. fishing mortality proxy) is above the limit reference point of <5, indicating fishing mortality is adequately controlled.  This is a change in the stock status classification of depleting from 2019 to 2021. Notably, (1) catch has also been reduced by 50% over the past three years, largely as an industry response to concerns over stock levels; and (2) the CZAF assessment, that includes a review of stock status, will be updated in late 2024 using data to 31/12/23.

The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Furthermore, the above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired. 

On the basis of the evidence provided above, the South Australia Central Zone Fishery management unit is classified as a sustainable stock.

South Australia Southern Zone Fishery

The most recent assessment report for the South Australia Southern Zone Fishery (SASZF) was completed in 2023 and reported on year-to-date data (October to April) for the 2022–23 season [Burnell and Hogg 2023]. The season in this fishery currently extends from 1 October to 30 September of the following year. Greenlip Abalone is typically harvested as a bycatch, although there is a separate total allowable commercial catch (TACC). The maximum catch of Greenlip Abalone in the SASZF was 19 t (whole weight) in 1968–69, but recent Greenlip Abalone catches have generally been small, being less than 5 t per season from 2013–14, with the current TACC set at 1.8 t. This reflects the low density and patchy distribution of Greenlip Abalone in the SASZF. There are inadequate data available to estimate biomass or exploitation rates. In addition, there is no knowledge of recruitment, and there are no defined target or limit reference levels in the harvest strategy [PIRSA 2021]. This prevents assessment of current stock size or fishing pressure. Consequently, there is insufficient information available to confidently classify the status of this stock. 

On the basis of the evidence provided above, the South Australia Southern Zone Fishery management unit is classified as an undefined stock.

South Australia Western Zone Fishery

The most recent assessment report for the South Australia Western Zone Fishery (SAWZF) was completed in 2023 and reported to the end of June 2023 [Stobart 2023]. The primary measures for biomass and fishing mortality are CPUE and fishery-independent surveys of legal-sized density by financial year [PIRSA 2021], with all reported metrics transitioning to financial year from 2021 onwards to align with the harvest strategy [Stobart et al. 2021]. 

The South Australian harvest strategy assesses the fishery performance against target reference points for two equally weighted performance measures (PM), CPUE and legal density (where available) of abalone from fishery independent surveys. A scoring function is applied to these PM’s based on agreed reference periods described in the management plan, with scoring based on limit (score 0) and target (score 5) reference points within a score range of 0 - 10 (PIRSA 2021). Performance is scored at a spatial assessment unit (SAU) scale designed to represent “approximate biological populations”, the SAU scores are catch weighted and aggregated to provide a zone score that forms the basis for setting total allowable catch for the following year. The zone score also enables determination of stock status that is based on trigger reference points for biomass (zone score used as a proxy) and fishing mortality (zone score trend used as a proxy). 

The total commercial catch for Greenlip Abalone in the SAWZF has declined by 48% from the stable catch over the decade ending 2009 (which averaged 81 t) to the 2023 catch (42.5 t) meat weight. This decline in catch was the combined effect of reductions, the removal of one licence during the elimination of displaced catch/effort as part of the implementation of state marine parks and voluntary reductions in catch by the commercial sector in 2015, 2016 and 2019 [Stobart et al. 2019, 2023]. 

The CPUE for Greenlip Abalone in the SAWZF remained relatively stable between 1980 and 1990 and then increased rapidly, reaching a peak of 30 kg per hour in 2005. From 2005, CPUE decreased substantially to 20 kg per hour in 2014. The CPUE then increased to 22 kg per hour in 2016, attributed to a combination of changing spatial and temporal fishing patterns and an increase in stock abundance [Stobart and Mayfield 2016]. However, this increase was not sustained, with CPUE again decreasing between 2015 and 2019 to 19.6 kg per hour, the fifth lowest value on record [Stobart et al. 2023]. The decline observed for the SAWFZ was widespread across fishing grounds and resulted in values that were amongst the lowest on record at the three most important Spatial Assessment Units (SAUs)—Anxious Bay, The Gap and Avoid Bay—from which 23 % of the Greenlip Abalone catch was obtained in 2019. Of the remaining Spatial Assessment Units (SAUs), most had relatively low values in 2019. Those declines occurred despite the change from fishing primarily in summer, when fish of a given shell length weigh least, to autumn when they weigh more [Stobart et al. 2013]. Subsequently, CPUE has increased steadily from 2019 to 24 kg per hour in 2023 , including the largest inter-annual increase in CPUE in the history of the SAWZF fishery occurring between 2022 and 2023. However, in contrast to these recent increases in CPUE, in 2022, legal density from fishery-independent surveys was relatively low at The Gap and the lowest value on record at Anxious Bay and Avoid Bay, as also was sub-legal-sized density. 

Application of the harvest strategy [PIRSA 2021] resulted in a zone score of 4.9 that, in combination with the zone trend score of 7.3 (reflecting an increasing trend), define the stock status for Greenlip Abalone in the WZ in the 2022–23 financial year as ‘sustainable’. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Furthermore, the above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired. 

On the basis of the evidence provided above, the South Australia Western Zone Fishery management unit is classified as a sustainable 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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