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Brownlip Abalone is found along Australia’s southwest coast. In WA there are two management areas, Area 2 Fishery is depleted and Area 3 fishery is sustainable. The stock in SA is undefined, with limited information available.

Brownlip Abalone is distributed from the south-west of Western Australia to the west of South Australia. Brownlip Abalone are endemic to the south-west of Australia, but there is evidence to suggest that they are genetically similar to, and potentially conspecific with, Blacklip Abalone (Haliotis rubra rubra) [Brown and Murray 1992], which are distributed east from Western Australia across southern mainland Australia to northern New South Wales and Tasmania. The biological stock structure of Brownlip Abalone has not been examined. As there is no genetic evidence to confirm biological stock structure of Brownlip Abalone, assessment of stock status is presented here at the management unit level—Western Australia Area 2 Fishery, Western Australia Area 3 Fishery and South Australia Western Zone Fishery.

Western Australia Area 2 Fishery

Brownlip Abalone catches in the Western Australia Area 2 and Area 3 Fisheries (WAA2F and WAA3F) are controlled by a Total Allowable Commercial Catch (TACC), set annually in accordance with harvest control rules defined in the Abalone Resource of Western Australia Harvest Strategy 2021–26 [DPIRD 2023]. The harvest control rule uses 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 outputs from model-based assessments that have provided estimates of biomass relative to the levels associated with Maximum Sustainable Yield (MSY); i.e., B_MSY. The target, threshold and limit reference levels for SCPUE in each management area are now equivalent to the values of SCPUE corresponding to estimated biomass at 1.2 B_MSY, B_MSY and 0.5 B_MSY, respectively [DPIRD 2023]. The Western Australia Area 2 Fishery is defined as depleted if the PI is below the limit reference level.

In the WAA2F, the annual SCPUE for Brownlip Abalone was relatively stable between 1999 and 2011, just under the threshold reference level. However, over the next five seasons (2012–16) the SCPUE declined markedly to below the limit reference level. The SCPUE then increased over the next two seasons (above limit in 2018) before declining again to below the limit (2019). The SCPUE has been below the limit reference level for the last four seasons. The Brownlip abalone SCPUE in the WAA2F has been at historical low levels for the last ten seasons since a sharp decline following the 2011 marine heatwave. The TACC was reduced to 50% of the long-term sustainable harvest level (MSY) in 2021 and further reduced to 25% of MSY in 2022 as directed by the harvest control rule in the revised Harvest Strategy [DPIRD 2023]. Brownlip Abalone mean meat weight (individual animal) has been relatively constant at 230 to 260 g since 2010, however this is lower than the 270 to 280 g for Brownlip Abalone caught through the early to mid-2000s [Hart et al. 2017]. The fishery has a legal minimum length of 145 mm, which allows 2–4 years of spawning to occur before recruitment to the fishery.

Results from biomass dynamics models applied to the available annual catch and SCPUE data for Brownlip Abalone in WAA2F, including a state space model [Winker et al. 2018], indicate that the stock is currently depleted. Thus, current biomass is estimated to be around the limit reference level (0.5 B_MSY). Estimates of fishing mortality (F) exhibit a general increasing trend from 1989 through to 2014, at which time the value was well above F_MSY (i.e., the long-term average level of fishing mortality required to achieve MSY), indicating that the stock was being overfished. Estimates of F have subsequently declined to well below F_MSY in the last two years, indicating that fishing mortality has been sufficiently reduced to allow stock recovery. The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely to be impaired. The above evidence further indicates that 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 2 Fishery management unit is classified as a depleted stock.

Western Australia Area 3 Fishery

Brownlip Abalone catches in the Western Australia Area 3 Fishery (WAA3F) are managed by the same Harvest Strategy and TACC setting process as described above in the WAA2F and defined in the Abalone Resource of Western Australia Harvest Strategy 2021–26 [DPIRD 2023]. In the WAA3F, the annual SCPUE for Brownlip Abalone fluctuated greatly during the 1999 to 2010 period. From 2011 to 2018, the SCPUE exhibited an increasing trend from below the threshold level to above the target (i.e., equivalent to 1.2 B_MSY). Over the last five seasons the SCPUE has fluctuated around the target reference level. Between 2012 and 2015 the TACC was reduced by 37.5%, after which time the SCPUE increased from below the threshold level to above the target by 2018. Brownlip Abalone mean meat weight (individual animal) in WAA3F increased from 230 g in 2013 to 271 g in 2019, reaching the 270 to 280 g meat weights that prevailed through the 2000s before declining sharply between 2009 and 2013 [Hart et al. 2017]. During the last three seasons, meat weights declined further to 256 g. The fishery has a legal minimum length of 150 mm, which allows 2–4 years of spawning to occur before recruitment to the fishery.

Results from biomass dynamics models applied to the available annual catch and SCPUE data for Brownlip Abalone in WAA3F, including a state space model [Winker et al. 2018], indicate that the stock is currently sustainable. Thus, current biomass is estimated to be above the target reference level (1.2 B_MSY). Estimates of fishing mortality (F) have remained below F_MSY (i.e., the long-term average level of fishing mortality required to achieve MSY) in most years between 1989 and 2022. In recent years, the values of F are well below estimated F_MSY, indicating that overfishing is not currently occurring. The above evidence indicates that current levels of fishing mortality and biomass of Brownlip Abalone in WAA3F are sustainable.

An integrated length-based stock assessment model [Strain et al. 2017], using data mainly from WAA3F but with some from WAA2F, has been applied to available data for Brownlip Abalone up to 2020, including commercial catch and SCPUE data, length composition data, and parameters associated with growth and reproduction. The integrated model estimated that the spawning biomass (relative to that for an unfished stock) has remained above the level equating to B_MSY in 2020, which implies that the stock in WAA3F is likely to have remained above this level. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

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

Brownlip Abalone biology [Strain et al. 2017; Strain et al. 2020]

Distribution of reported commercial catch of Brownlip Abalone

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

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

1. Brown, LD and Murray, ND 1992, Genetic relationships within the genus Haliotis. In: Abalone of the World: Biology, Fisheries and Culture. Shepherd, SA, Tegner, MJ, and Guzman del Proo, SA (eds). Blackwell Scientific Publications Ltd, Oxford, pp.19–23.
2. DPIRD 2023, Abalone resource of Western Australia harvest strategy 2021–2026: Version 2.0. Fisheries Management Paper No. 283. Department of Primary Industries and regional Development, Western Australia, Perth. 53pp.
3. Hart, A, Strain, L, Hesp, A, Fisher, E, Webster, F, Brand-Gardner, S and Walter, S 2017, Marine Stewardship Council full assessment report Western Australian Abalone Managed Fishery. Department of Fisheries, Western Australia, Perth. 288pp.
4. Smallwood, CB, Ryan, KL, Lai, EKM, Rudd, LJ and Strain LWS 2023, Recreational fishing for Abalone in Western Australia in 2021/22: estimates of participation, effort and catch. Fisheries Research Report No. 333. Department of Primary Industries and Regional Development, Western Australia. 33pp.
5. Strain, LWS, Hesp, SA, Fabris, F, and Hart, AM 2017, Demographic performance of Brownlip abalone: exploration of wild and cultured harvest potential. FRDC Project No. 2012/016. Fisheries Research Report No. 280. Department of Fisheries, Western Australia, Perth. 104pp.
6. Winker, H, Carvalho, F, and Kapur, M 2018, JABBA: Just Another Bayesian Biomass Assessment. Fisheries Research 204; 275-288.