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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. 

Victoria Central Zone Fishery

Blacklip Abalone commercial catch per unit effort (CPUE) doubled from about 50 kg per hour in the early 1980s to around 100 kg per hour in the early 2000s, a pattern consistent throughout the state. The increase is thought to be at least partly due to changes in fishing practices that improved fishing efficiency [VFA 2017a]. Similar patterns have been observed during the same period in the other Australian Blacklip Abalone jurisdictions, and have been partially attributed to increased exploitable biomass. The introduction of a total allowable commercial catch (TACC) in the Victoria Central Zone in 1988 was expected to improve biomass and contribute to CPUE increases to some extent. The TACC was stable for more than a decade prior to the introduction of marine parks which reduced the available fishing grounds, probably because catch quotas were not linked to biomass trends at that time [Victorian Department of Natural Resources and Environment 1996].

Since the peak in the early 2000s CPUE has shown a declining trend, and by 2017–18 was almost one quarter lower at 74 kg per hour. Some of the smaller short-term fluctuations in CPUE during the past decade may be attributable to increases and decreases in abalone size limits. The abalone viral ganglioneuritis (AVG) outbreak west of Cape Otway contributed to a 50 t decline in catches and probably reduced catch rates to some extent. The TACC was reduced substantially from 620 t in 2006–07 to 285 t in 2010–11, following which it fluctuated between years by up to 8 per cent. Landings in 2021/22 were 241.4 t, 96% of the TACC [Dixon et al. 2023]. 

Trends in abundance estimated from fishery-independent survey (FIS) data were consistent with observed declines in CPUE, showing a major decline since 2003 of approximately 50–60 per cent in the relative abundance of sub-legal sized (pre-recruit) and legal-sized (recruit) abalone. Both of these FIS indices have been relatively stable since 2010, with recruit abundance increasing for the last three years. Although there are no prescribed reference points for these fishery-independent indicators of stock status, a draft harvest strategy specifies CPUE reference points with limits ranging from 40–50 kg per hour, thresholds from 60–70 kg per hour, and targets from 70–130 kg per hour among 11 of the 12 defined spatial management units (SMU) for which the Central Zone fishery is regulated [Dixon et al. 2023]. In the absence of recent catches, the Port Phillip Bay SMU was excluded. Current CPUE values in 2021/22 were between 49.5–89.5 kg per hour among the SMU, all above the limit reference points but with three below their respective thresholds and none above the target [Dixon et al. 2023]. 

The stable, or slightly increasing, abundances observed in FIS indices indicate that the decline in biomass observed over two decades may have stabilised, or possibly begun to reverse, but on balance, the stocks across the zone appear to be depleting, particularly over longer time frames, which is how the information must be interpreted given uncertainties in both CPUE and FIS abundances [Dixon et al. 2023]. Importantly, however, pre-recruit abundance levels are similar to those for recruits, implying that reasonable recruitment has been occurring at recent stock levels. The current challenge facing the fishery is ensuring that the spatial distribution of catch is aligned with catch targets that reflect the biological productivity of the resource and enable stocks to rebuild. 

The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. For the period 2009/0–2021/22 the biomass declined, but the stock is not yet considered to be recruitment impaired. Evidence based on the pre-recruit abundance index indicates that reasonable recruitment has been occurring at recent stock levels [Dixon et al. 2023].

On the basis of the evidence provided above, the Victoria Central Zone Fishery management unit is classified as a depleting stock.

Victoria Eastern Zone Fishery

The Eastern Zone management unit was not affected by abalone viral ganglioneuritis (AVG) but has experienced impacts from environmental and ecosystem changes such as increasing abundance of the Longspined Sea Urchin (Centrostephanus rodgersii). These urchins denude reefs of macro-algae, turning them into ‘barrens’ that are unsuitable for abalone, with significant areas of reef in the Eastern Zone having been affected by urchins in this manner over the past 20 years [Gorfine et al. 2012]. It is also likely that reproductive capacity has been reduced by habitat loss caused directly by the increased density of urchins [Bell 2020]. Industry has a history of stewardship and working with fishery managers to sustain the fishery, including active control of urchins for more than ten years. However, increasing abundance of urchins may have led to an increased concentration of fishing effort on urchin-free reef areas, with an increased associated risk of localised depletion.  

In common with other jurisdictions, improvements in fishing methods (e.g. transition to live-boating) have also occurred in this management unit and are thought to have contributed to fishing efficiency-related increases in catch per unit effort (CPUE) from the mid-1990s to early 2000s. The introduction of a total allowable commercial catch (TACC) in the Victoria Eastern Zone in 1988 was expected to improve biomass and contribute to CPUE increases to some extent. The TACC was stable for more than a decade prior to the introduction of marine parks which reduced the available fishing grounds, probably because catch quotas were not linked to biomass trends at that time [Victorian Department of Natural Resources and Environment 1996].

The Eastern Zone catch was relatively stable from 1992 to 2002, ranging from 431 to 445 t per quota year before increasing to 480 t in 2003. Catch was maintained at this level until 2008 and has slowly declined thereafter. Landings in 2020/21 were 282.3 t, the lowest on record, with the TACC being under-caught as a result of COVID restrictions and market conditions. In 2021/22, landings increased to 357.0 t, with the inclusion of a carryover from the previous seasons’ under-caught TACC [Dixon et al. 2022].

Standardised CPUE significantly increased from 1992 to 2011, before significantly declining over five years from 2011 to 2016, then increasing again from 2016 to 2019. In 2020/21, CPUE reduced, which was at least partially a result of market demand for large, live abalone, and CPUE increased in 2021/22. Current CPUE values in 2021/22, for all seven Spatial Management Units (SMU), are well above the limit reference point of 50 kg per hour specified throughout the Eastern Zone, as well as SMU threshold and target reference points specified in a draft harvest strategy, that vary respectively between 70–80 kg per hour and 100–130 kg per hour [Dixon et al. 2022]. However, a review of CPUE standardisation, and the reliability of catch rate as a proxy for biomass more generally, has revealed that CPUE is likely to be relatively unreliable in this fishery [Dixon et al. 2022].

In contrast with the CPUE trends, the fishery-independent survey indices show that pre-recruit abundance has declined by almost 70 per cent from historically high levels in 1995. The survey index of recruit abundance declined by 50 per cent and has since remained relatively stable in most SMU [Dixon et al. 2022]. However, a review of the fishery independent surveys is currently underway with preliminary indications that the fishery has since moved inshore following the depletion of deeper areas and thus the fishery independent surveys may provide limited information on the biomass of the stock where much fishing is currently concentrated [Dixon et al. 2022].

Given the uncertainties around both CPUE and the fishery independent surveys, there is considerable uncertainty in the trajectory of the biomass in the Victorian Eastern Zone management unit [Dixon et al. 2022]. However, it is apparent that there have been significant declines in biomass over the last 2–3 decades, and recent landings have not been consistent with targets meaning several SMU have received a disproportionally high level of fishing pressure [Dixon et al. 2022] and are therefore likely to have experienced further declines in biomass. Coupled with the effects of increased urchin abundance, the available evidence indicates that the biomass of Blacklip Abalone in the Victorian Eastern Zone management unit is still declining, but not to the extent that the stock could be considered to have become depleted or recruitment impaired. 

On the basis of the evidence provided above, the Victoria Eastern Zone Fishery management unit is classified as a depleting 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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