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Of the six Sandfish stocks defined by either the biological stock or management unit level, three are undefined (Gulf of Carpentaria, North West Northern Territory, Queensland), one is sustainable (Kimberley), and two are depleted (Pilbara, Torres Strait).

Photo credit: NT Fisheries

Jurisdiction	Stock	Stock status	Indicators
Commonwealth	Torres Strait	Depleted	Biomass, survey densities, historical catch
Northern Territory	Gulf of Carpentaria	Undefined
Northern Territory	North West Northern Territory	Undefined
Queensland	Queensland	Undefined	Catch, CPUE, Management Evaluation
Western Australia	Kimberley	Sustainable	Modelled Biomass, CPUE, Fishery independent surveys
Western Australia	Pilbara	Depleted	Modelled Biomass, CPUE, Fishery independent surveys

Sandfish (Holothuria scabra) is widely dispersed in shallow water on soft sediments throughout the Indo-Pacific region, bounded by the East Coast Africa, the tropics of Cancer and Capricorn and west of the mid Pacific Ocean. Gene flow investigations for H. scabra populations along the north and east coasts of Australia concluded that populations can be grouped into at least 3 genetically distinct stocks: (1) southern populations from the Hervey Bay area, (2) one population from the central coast of Queensland, and (3) populations from Torres Strait (Uthicke and Benzie, 2001). The last region is closely related to samples from the Solomon Islands. A similar result was reported by Gardner et al. [2012] in relation to H. scabra populations within Northern Territory waters, suggesting the existence of genetically distinct stocks in the Gulf of Carpentaria (or eastern population) and the Arafura Sea (or western population). No equivalent studies have been done in Western Australia. However, based on the existing knowledge from isolation by distance models, it was assumed that the Kimberley and Pilbara populations of H. scabra are separate stocks for management purposes. The sandfish stock in Torres Strait is concentrated on the Warrior Reefs complex, which bridges Australia and Papua New Guinea (PNG). Sandfish in Torres Strait is assumed to be a single biological stock for assessment and management purposes. Thus, six Australian stocks of Sandfish are currently recognised for management and assessment purposes.

Here, assessment of stock status for Sandfish is presented at the biological stock level—Gulf of Carpentaria, North West Northern Territory, Kimberley Western Australia and Pilbara Western Australia—and the management unit level—Torres Strait and Queensland.

Gulf of Carpentaria

Sandfish comprise of approximately 99% of the catch in the Northern Territory Trepang Fishery. Sandfish catches in the Trepang Fishery are managed through a tiered grid catch limit system, which allocates a total allowable harvest in specified fishing grids. Recent catch in this stock is low compared to historical catches. Catch from the Gulf of Carpentaria biological stock was 14 t in the 2021–22 financial year. The annual average catch in the last 10 years was 24 t (2011–12 to 2022–23), which is almost half the annual average of the preceding 10 years (43 t). This coincides with a reduction in average annual effort (in dive hours) in the Gulf of Carpentaria stock from 505 hours for 2001–02 to 2010–11 to 259 hours for 2011–12 to 2022–23. It is uncertain if the decline in catch and effort is driven by operational/economic decisions or due to changes of stock abundance. There is insufficient information available to classify the status of this stock. 

On the basis of the evidence provided above, the Gulf of Carpentaria is classified as an undefined stock.

Kimberley

Harvest of Sandfish (H. scabra) in Western Australia is managed by a formal harvest control rule (HCR) as defined in the Western Australian Sea Cucumber Resource Harvest Strategy 2018–22 [DPIRD 2018]. This is updated annually during resource assessments [Hart et al. 2022], and in response to external audits from the Marine Stewardship Council (MSC) conformity assessment bodies [MSC 2023]. The main performance indicator (PI) is a biomass estimate from a population model, which uses catch, catch rate, and fishery independent survey data [Hart et al. 2022]. The PI is compared against reference levels defined as: Target (50% B0), threshold (40% B0) and limit (30% B0), where B0 is unfished biomass. The HCR has pre-defined management actions in response to the PI, and it is embedded within a larger harvest strategy that employs a risk-based, weight-of-evidence approach using 7 different lines of evidence.

The population model estimated an initial decline occurred to 0.4 B0 during 1995–99, but it was highly unlikely that biomass was reduced below 0.8B0 between 2006 and 2022. Also, the average weight of sandfish harvested in the Kimberley in the period 2004 to 2022 was 3 times the estimated size-at-maturity and stable over time. Based on these lines of evidence, there are no indications of unacceptable stock depletion in 2022. The stock is not considered to be recruitment impaired and the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

 

On the basis of the evidence provided above, Kimberley Sandfish in Western Australia is classified as a sustainable stock

 

North West Northern Territory

Sandfish comprise of approximately 99% of the catch in the Northern Territory Trepang Fishery. Sandfish catches in the Trepang Fishery are managed through a tiered grid catch limit system, which allocates a total allowable harvest in specified fishing grids. In the North West Northern Territory stock there has been a significant reduction effort from the historic peak. Effort has reduced from an annual average of 809 hours (1991–92 to 2000–01) to 302 hours in the last 10 years (2011–12 to 2022–23). In a similar trend, average catch has reduced from 70 t per year (1991–92 to 2000–01) to 31 t per year (2011–12 to 2022–23). There has also been a spatial contraction of effort in this stock. It is unclear if this has been driven by stock declines in unfished locations or driven by operational/economic decisions. Catch from the North West Northern Territory biological stock was 28 t in the 2021–22 financial year. It is uncertain if the decline in catch and effort is driven by operational/economic decisions or due to changes of stock abundance. There is insufficient information available to classify the status of this stock. 

On the basis of the evidence provided above, the North West Northern Territory stock is classified as an undefined stock.

 

Pilbara

Harvest of Sandfish (H. scabra) in Western Australia is managed by a formal harvest control rule (HCR), as defined in the Western Australian Sea Cucumber Resource Harvest Strategy 2018–22 [DPIRD 2018]. This is updated annually during resource assessments [Hart et al. 2022] and in response to external audits from the MSC conformity assessment bodies [MSC 2023]. The main performance indicator (PI) is a biomass estimate from a population model, which uses catch, catch rate, and fishery independent survey data [Hart et al. 2022]. The PI is compared against reference levels defined as: Target (50% B0), threshold (40% B0) and limit (30% B0), where B0 is unfished biomass. The HCR has pre-defined management actions in response to the PI, and it is embedded within a larger harvest strategy that employs a risk-based, weight-of-evidence approach using 7 different lines of evidence.  

The population model estimated a decline to 25% B0 during 2017 to 2022, which is below the limit reference point.  This suggested the point of recruitment impairment had been breached.  Also catch rates reduced significantly during 2015 to 2019, and a fishery independent survey detected an 80% reduction in biomass between 2017 and 2020. Based on these lines of evidence, there are indications of unacceptable stock depletion in 2022. Under the HCR a 3-year closure of the Sandfish fishery is required, and the fishery has been formally closed by legislation until 31 July 2026. The above evidence indicates that the biomass of this stock is considered 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.

On the basis of the evidence provided above, Pilbara Sandfish in Western Australia is classified as a depleted stock.

 

Queensland

Sandfish in Queensland are harvested by hand across the Queensland east coast (including the Great Barrier Reef Marine Park (GBRMP). Historically, most of the Sandfish harvest was from Hervey Bay and Tin Can Bay [Breen 2001; Roelofs et al. 2003], however these areas were closed to fishing in 2001 due to declining catch rates [DEH 2004; QDPIF 2004]. At its peak, over 70 t of Sandfish were reported as fished in 1996–97 [Skewes et al. 2014]. Fishers reported the early Sandfish catches were almost entirely inshore sandfish, Holothuria scabra. After the closures of Hervey Bay and Tin Can Bay, Sandfish collection was allowed to continue in the rest of the fishery area, although the species composition collected in the sea cucumber fishery changed with Sandfish no longer being targeted. Catch data for H. scabra (2.7 t in 2020–21 and 0 t in 2021–22) included in this report may be inaccurate as there are four species of Sandfish collected in Qld waters—H. scabra (Sandfish), H. lessoni (Golden Sandfish), Bohadschia vitiensis (Brown Sandfish), B. marmorata (Brown Sandfish). Catch for all species of Sandfish was 11.5 t in 2021–22. Although some H. scabra will be included in this catch, the fishery no longer targets H. scabra and is more likely to pick up the deeper water species of Sandfish when targeting other species in the fishery.

The fishery is managed under the Queensland Sea Cucumber Fishery Harvest Strategy 2021–2026, as well as under a rotational zoning scheme (RZS). Since 2000, Sandfish catches have ranged from a high of 34 t in 2005–06 to less than 200 kg in 2012–13. Management strategy evaluation (MSE) of the RZS determined that the risk of the fishery depleting Sandfish biomass to below 40% of unfished biomass was very low under Queensland Sea Cucumber (East Coast) Fishery management arrangements [Skewes et al. 2014]. Spatial closures in the Great Barrier Reef Marine Park also protect an estimated 48% of the Sandfish spawning biomass [Skewes et al. 2014]. Sandfish are considered a Tier 2 species under the harvest strategy and have a trigger reference point of 15 t, where management considers if action is required. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired.

While noting the above there remains a degree of uncertainty surrounding catch compositions and it is difficult to quantify the harvest rate of H. scabra. This in turn makes it difficult to confidentially classify the status of this stock.

On the basis of the evidence provided above Sandfish (H. scabra) in the East Coast sea cucumber fishery are classified as an undefined stock.

Torres Strait

Sandfish harvest in Torres Strait is concentrated on Warrior Reefs, with more than 100 years of boom-and-bust exploitation on both sides of the border with PNG. The latest boom on the Australian side was during the 1990s, with catch estimated to exceed 1 200 t in 1995 [Skewes et al. 2004]. Peak reported catch since 1996 was 30 t in 1997. Sandfish was subsequently considered to be overfished and has been subject to a zero total allowable catch (TAC) since 1998.  

The last survey of sandfish in Torres Strait was in 2010 [Murphy et al. 2011]. At that time, survey densities were estimated to be around 80% lower than in 1995, when the stock was already considered to be depleted. Results from the 2010 survey indicated a mean density (± standard error) of 94 ± 50 sandfish per hectare, which was similar to the 2004 estimate (94 ± 25 sandfish per hectare), suggesting that there had been no recovery up to the time of the 2010 survey. Skewes et al. [2006] estimated that a density of 1 600 sandfish per hectare would have been required to enable the 1 200 t harvested in 1995. Densities reported from surveys in 2004 and 2010 were less than 6% of that level. This indicates that the stock was substantially reduced and likely below the limit reference point (LRP) of 40% of unfished biomass [Butler et al. 2022].  

The reason for the lack of observable recovery of sandfish between 1998 and 2010 is not clear, given that the fishery has been closed since 1998. Murphy et al. [2011] suggested several possible causes, including poor recruitment and illegal fishing. There is increasing anecdotal evidence regarding illegal fishing on Warrior reef, likely targeting sandfish. However the extent of illegal take of sandfish has not been confirmed [Butler et al. 2023].

The recent survey of sea cucumbers in 2019–20 in Torres Strait [Murphy et al. 2021] did not cover the Warrior Reefs complex and so did not provide an update on the sandfish stock.  

The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely to be impaired.  

On the basis of the evidence provided above, the Torres Strait (Commonwealth) management unit is classified as a depleted stock.

Sandfish biology [Hamel et al. 2001; Kithakeni and Ndara 2002; Skewes et al. 2014].

Species	Longevity / Maximum Size	Maturity (50 per cent)
Sandfish (Sea Cucumber)	6–10 years	Females 200mm, Males 140–170mm

Distribution of reported commercial catch of Sandfish.

	Commonwealth	Western Australia	Northern Territory	Queensland
Commercial
Diving
Unspecified
Commercial
Hand collection
Indigenous
Diving
Recreational
Diving

Method	Commonwealth	Western Australia	Northern Territory	Queensland
Commercial
Area closures
Boat limits
Catch limits
Fishing gear and method restrictions
Gear restrictions
Harvest Strategy
Individual transferable quota
Limited entry
Limited entry (licensing)
Processing restrictions
Seasonal or spatial closures
Total allowable catch
Vessel restrictions
Recreational
Bag/possession limits
Boat limits
Gear restrictions
Seasonal or spatial closures

	Commonwealth	Western Australia	Northern Territory	Queensland
Commercial			41.29t

Commonwealth – Recreational. The Australian Government does not manage recreational fishing in Commonwealth waters. Recreational fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters, under its management regulations.

Commonwealth – Commercial (catch). Catch is by calendar year. All catch is Indigenous.

Commercial catch of Sandfish - note confidential catch not shown.

1. Breen, SB 2001, Queensland East Coast Bech-de-mer Fishery Statement of Management Arrangements. Queensland Fisheries Services. 22 pp.
2. Butler, I, D'Alberto, B and Cao, A 2023, Torres Strait Bêche-de-mer and Trochus fisheries, in Butler, I, Patterson, H, Bromhead, D, Galeano, D, Timmiss, T, Woodhams, J and Curtotti, R (eds), Fishery status reports 2023, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra.
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13. QDPIF 2004, Ecological assessment of Queensland's East coast Beche-de-mer Fishery. Department of Primary Industries and Fisheries, QLD.
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