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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

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.

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].

Distribution of reported commercial catch of Sandfish.

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.

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