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Blacklip Abalone is harvested in NSW, SA, TAS and VIC, with twelve management zones. Stocks are sustainable in six zones, depleting in two zones, depleted in two zones, undefined in one zone and negligible in one zone.

There are substantial difficulties in applying classical stock assessment models to abalone resources, given the possibly large number of stocks in each fishery, and that stock structure in abalone depart substantially from dynamic pool assumptions required by integrated models. In some regions Haliotis rubra rubra also displays spatially variable growth rates and maturity curves. All jurisdictions therefore rely on indicators and empirical performance measures. Primarily these are commercial catch and catch per unit effort (CPUE; as kg of abalone harvested per hour). but they can also include commercial catch per area searched (CPUA), and metrics derived from fishery independent surveys, and commercial and fishery-independent size composition.   CPUE and similar indicators from individual fishing events are relevant locally but are not indicative of status broadly [Parma et al. 2003], and status of the many populations within a management unit cannot be assumed to be trending in the same direction. Thus, it is only the average CPUE across each spatial reporting unit that provides the broader perspective for fishery assessment. Fishery assessment is usually based on a combination of indicators, and some jurisdictions combine the indicators to give a combined score for stock status. The annual catch by Blacklip Abalone fisheries is generally close to the established total allowable commercial catches (TACCs), with little over-catch or under-catch of the TACC. 

South Australia Central Zone Fishery

The fourth management plan for the South Australian Abalone Fishery (SAAF) was developed from 2015–16 to 2019–20 and is currently in draft form (PIRSA 2020 in prep). The draft management plan includes the draft harvest strategy intended to be the primary tool used to achieve the goal of sustainably harvesting the abalone resource and allocating stock status in accordance with the National Status Reporting Framework (NSRF). The draft harvest strategy provides a structured, species-specific and spatially explicit framework for decision making and includes assignment of stock status consistent with the NSRF. It has three main phases: (1) a monitoring phase in which information is collected for the two performance indicators, catch per unit effort (CPUE) and legal density of abalone from fishery-independent surveys (FIS), along with other relevant fishery information; (2) the stock assessment phase where the performance of each spatial assessment unit (SAU; minimum spatial scale currently used to assess the fishery) is scored based on a CPUE score and, for some key SAUs, a legal density score. This scoring is based on a range from 0 to 10 where the target reference point is 5 and the limit reference point is 0. Aggregated scores for the SAUs provide an overall stock status based on trigger reference points for biomass (zone score used as a proxy) and fishing mortality (zone score trend used as a proxy); and (3) the final step where zone score is translated to a recommended zonal catch. During this step a workshop is held with industry to share relevant information, and zonal catch can be adjusted within a 10 per cent range based on the information through harvest decision rules. The adjusted zonal catch helps to inform a total allowable commercial catch (TACC) for the following season.

Following the implementation of a TACC in 1990, Blacklip Abalone catches and CPUE in the South Australia Central Zone Fishery (SACZF) were stable for more than a decade, at ~13 t meat weight per year and ~25 kg meat weight per hour, respectively. A long-term decline in CPUE began in the mid-2000s, and despite multiple reductions in TACC from 14.1 to 6.4 t, by 2016 CPUE had declined to 21 kg per hour. In 2017, CPUE declined further to 18 kg per hour, which was the lowest catch rate on record (38 years) and 12 per cent below the next lowest value. At the start of the 2018 season, the fishery was voluntarily closed by industry, with the TACC set at zero, and was subsequently classified as ‘depleted’. These declines in catch rate, despite the reduced catches, indicate that recent recruitment levels have been substantially below those that have historically supported substantially larger catches. There had also been an apparent spatial contraction of the fishery, principally into the south-western corner of Kangaroo Island, from a previously broader spatial distribution across the south coast of Kangaroo Island.

The most recent assessment for the SACZF was completed in 2020, reporting up to the conclusion of the 2019 calendar season [Burnell et al. 2020a]. The key indicator for biomass and fishing mortality is commercial CPUE. While the TACC of 6.4 t was reinstated in 2019, catches were limited under an industry-managed agreement, with approximately 1 t of Blacklip Abalone harvested. These small catches, often taken as a bycatch when targeting Greenlip Abalone, were insufficient to estimate CPUE, or infer changes in stock biomass. Application of the proposed harvest strategy in 2019 resulted in a zone score of 0.6 that, in combination with the zone trend score of 4.4 (reflecting a decreasing trend), define the stock status for Blacklip Abalone in the SACZF in 2019 as ‘depleted’.

The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely to be impaired. Furthermore, the above evidence indicates that current fishing mortality has been reduced 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.

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

South Australia Southern Zone Fishery

The fourth management plan for the South Australian Abalone Fishery (SAAF) was developed from 2015–16 to 2019–20 and is currently in draft form (PIRSA 2020 in prep). The draft management plan includes the draft harvest strategy intended to be the primary tool used to achieve the goal of sustainably harvesting the abalone resource and allocating stock status in accordance with the National Status Reporting Framework (NSRF). The draft harvest strategy provides a structured, species-specific and spatially explicit framework for decision making and includes assignment of stock status consistent with the NSRF. It has three main phases: (1) a monitoring phase in which information is collected for the two performance indicators, catch per unit effort (CPUE) and legal density of abalone from fishery-independent surveys (FIS), along with other relevant fishery information; (2) the stock assessment phase where the performance of each spatial assessment unit (SAU; minimum spatial scale currently used to assess the fishery) is scored based on a CPUE score and, for some key SAUs, a legal density score. This scoring is based on a range from 0 to 10 where the target reference point is 5 and the limit reference point is 0. Aggregated scores for the SAUs provide an overall stock status based on trigger reference points for biomass (zone score used as a proxy) and fishing mortality (zone score trend used as a proxy); and (3) the final step where zone score is translated to a recommended zonal catch. During this step a workshop is held with industry to share relevant information, and zonal catch can be adjusted within a 10 per cent range based on the information through harvest decision rules. The adjusted zonal catch helps to inform a total allowable commercial catch (TACC) for the following season.

Catches of Blacklip Abalone in the South Australia Southern Zone Fishery (SASZF) were consistent around 140 t after TACCs were introduced in the early 1990s. Commercial CPUE increased consistently through time, almost doubling between the mid-1980s and 2010–11. Following record high CPUE (~122 kg per hour) and TACC-constrained catch (~150 t) between 2010–11 and 2011–12, a number of key indicators of stock performance began to decline across the SZ. Subsequently, the fishery was classified as ‘depleting’ between 2013–14 and 2015–16, and TACCs decreased from 151.5 t to 126 t. Preceding this period of depleting stock status, widespread abalone mortalities were reported across the SASZF as a result of anomalously high water temperatures during the summer of 2012–13, which likely contributed to stock decline.

The most recent assessment report for the SASZF was completed in 2020 and reported up to the conclusion of the 2018–19 season [Burnell et al. 2020b]. The primary measures for biomass and fishing mortality are commercial CPUE and FIS of legal-size abalone density. During the past two fishing seasons CPUE in the SASZF has increased to levels slightly below historical peaks (~112 kg.hr^-1). Estimates of CPUE for most SAUs were increasing and/or well above historical averages, while the FIS indicate the number of abalone at key locations within the fishery have been relatively stable over the last five seasons. In 2018–19, these stable or increasing proxies for biomass, were accompanied by a modest increase in catch and TACC from 126 to 132 t. This current position of the stock contrasts with the period of declining stock status and relative instability prior to 2016.

Application of the proposed harvest strategy in 2018–19 resulted in a zone score of 7.0 that, in combination with the zone trend score of 6.4 (reflecting an increasing trend), define the stock status for Blacklip Abalone in the SASZF in 2019 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 Southern Zone Fishery management unit is classified as a sustainable stock.

South Australia Western Zone Fishery

The fourth management plan for the South Australian Abalone Fishery (SAAF) was developed from 2015–16 to 2019–20 and is currently in draft form (PIRSA 2020 in prep). The draft management plan includes the draft harvest strategy intended to be the primary tool used to achieve the goal of sustainably harvesting the abalone resource and allocating stock status in accordance with the National Status Reporting Framework (NSRF). The draft harvest strategy provides a structured, species-specific and spatially explicit framework for decision making and includes assignment of stock status consistent with the NSRF. It has three main phases: (1) a monitoring phase in which information is collected for the two performance indicators, catch per unit effort (CPUE) and legal density of abalone from fishery-independent surveys (FIS), along with other relevant fishery information; (2) the stock assessment phase where the performance of each spatial assessment unit (SAU; minimum spatial scale currently used to assess the fishery) is scored based on a CPUE score and, for some key SAUs, a legal density score. This scoring is based on a range from 0 to 10 where the target reference point is 5 and the limit reference point is 0. Aggregated scores for the SAUs provide an overall stock status based on trigger reference points for biomass (zone score used as a proxy) and fishing mortality (zone score trend used as a proxy); and (3) the final step where zone score is translated to a recommended zonal catch. During this step a workshop is held with industry to share relevant information, and zonal catch can be adjusted within a 10 per cent range based on the information through harvest decision rules. The adjusted zonal catch helps to inform a total allowable commercial catch (TACC) for the following season.

In response to a depleting stock status from 2013 onwards, the TACC in the South Australia Western Zone Fishery (SAWZF) was reduced in 2013, 2014, 2016, 2018 and 2019. The total catch was further reduced through a voluntary reduction in catch by the commercial sector in 2015, 2016 and 2019 [Stobart et al. 2020]. Overall, this resulted in a 45 per cent catch reduction from 93.4 t in 2012 to 51.1 t in 2019.

The most recent assessment for the SAWZF was completed in 2020 and reported up to the conclusion of the 2019 financial year season [Stobart et al. 2020]. The primary measures for biomass and fishing mortality used are commercial CPUE and FIS of legal-sized density by financial year. The financial-year CPUE for Blacklip Abalone in the SAWZF increased from 24.4 kg per hour in 1979 to 30.7 kg per hour in 2005, the highest level on record. CPUE then decreased and, in 2018, was 20.0 kg per hour, the lowest value on record. CPUE has subsequently increased to 21.4 kg per hour in 2019. With one exception, the long-term declining trend between 2005 and 2018 occurred across all of the high and medium importance SAUs for the fishery [Stobart et al. 2020]. Estimates of legal-sized density from FIS also show general decreases following the late 2000s, with subsequent stabilisation or increases by 2019, generally matching the observed CPUE trend. The recent increase in CPUE and increases in legal density from most FIS sites suggest that the reductions in catch may now have arrested the observed declines in CPUE from 2005 to 2018. The trend reversal in both metrics is evidence that, although biomass is low, fishing mortality is likely to be adequately controlled to avoid the stock becoming recruitment impaired. Additional years of CPUE and FIS data are required to confirm the recent change in harvestable biomass trajectory remains.

Application of the proposed harvest strategy resulted in a zone score of 3.3 that, in combination with the zone trend score of 5.04 (reflecting an increasing trend), define the stock status for Blacklip Abalone in the WZ in the 2019–20 FY 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 abovethe South Australia Western Zone Fishery management unit is classified as a sustainable stock.

Blacklip Abalone biology [Shepherd 1973, Officer 1999, Tarbath et al. 2001, Tarbath and Officer 2003]

Distribution of reported commercial catch of Blacklip Abalone

New South Wales – Indigenous (Management Methods) https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing

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.

Commercial catch of Blacklip Abalone - note confidential catch not shown

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