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Australia has four stocks of Commercial Scallop. Two are sustainable – the Bass Strait Central Zone Scallop Fishery and the Port Phillip Bay Dive Scallop Fishery. One is classified as depleted (Victoria’s Ocean Scallop Fishery), and one is classified as a recovering stock (the Tasmanian Scallop Fishery).

There are several Commercial Scallop bed regions fished commercially in Commonwealth, Victorian and Tasmanian waters. Commercial Scallops in Port Phillip Bay (Victoria) and D’Entrecasteaux Channel (Tasmania) are genetically distinct from conspecifics in most other locations in south-eastern Australia [Woodburn 1990; Semmens et al. 2015; Ovenden et al. 2016]. Beds in north-eastern Bass Strait are also genetically distinct to adjacent Bass Strait beds and may not contribute to wider recruitment based on biophysical models of larval movement [Ovenden et al. 2016].  

Here, assessment of stock status is reported at the management unit level—Bass Strait Central Zone Scallop Fishery (Commonwealth), Ocean Scallop Fishery (Victoria), Port Phillip Bay Dive Scallop Fishery (Victoria) and Tasmania Scallop Fishery.

Tasmania Scallop Fishery

The Tasmanian Scallop Fishery (TSF) is managed under a harvest strategy where surveys are undertaken to estimate abundance and decision rules are used to open or close an area (or areas) to fishing with TACs based on the estimated abundance. Like the Bass Strait Central Zone Scallop Fishery (Commonwealth) (BSCZSF), these decision rules include a minimum size limit and a maximum discard rate, which is not to exceed 20%. The minimum size limit is 90 mm shell length (noting that this can be varied with an exemption); animals of this size are approximately 3 years of age and have spawned at least twice [Young et al. 1989]. Unlike the BSCZSF, until recently there was no requirement to close a proportion of the beds surveyed in a particular region of the fishery. Instead, protection of scallop habitat, which may contain scallop beds, was only afforded through a ban on scallop dredging in waters less than 20 m and a network of dredge-prohibited areas around the state. However, since the 2022 scallop season, to open one of the six TSF Scallop Fishery Areas for harvest with a total allowable catch (TAC) equal to or greater than 1,000 t, an area with a minimum estimated biomass of 1,000 t of scallop with a ‘medium’ density (approximately 0.6 scallops/m2) that meets the discard criteria must be closed to commercial fishing for the entire season as a spawning biomass closure. To open a Scallop Fishery Area with a TAC less than 1,000 t, a spawning biomass closure equivalent to the TAC must be established.

Biomass in the TSF is historically overfished with recruitment and production levels now affected. In 2013, 2014 and 2015, surveys generally found low scallop densities and limited evidence of successful recent recruitment but did identify two beds (one on the north-west coast and the other on the east coast) containing commercial quantities [Semmens et al. 2018]. Surveys in 2016 and again in 2017 generally only found very low levels of scallop abundance and limited evidence of successful recruitment, with no area considered to contain commercially viable quantities in either year. This includes the east and north-west coast beds fished in 2013–15, which appeared to have been fished down to a commercially unviable density at the time, with no subsequent recruitment evident. Given the results of the 2016 and 2017 surveys, there was a low expectation that conducting surveys in 2018 and 2019 would reveal the presence of commercially viable scallop beds, and as such, surveys were not conducted. In 2020 surveys were again conducted, and the results were dominated by low to moderate densities of legal sized scallops in multiple areas, including the east coast beds (which were fished in 2013–15) and the Flinders Island region adjacent to the BSCZSF. This demonstrated signs of recruitment that suggested the possibility of supporting a commercial fishery in the near- to medium-term post 2020.  

The 2021 survey subsequently covered three Flinders Island beds (Scallop Fishery Area 3) with an estimated legal-sized (greater than 90 mm SL) biomass of 17,145 t, one central east coast bed (Scallop Fishery Area 4) with an estimated legal-sized biomass of 384 t and one lower east coast bed (Scallop Area 5) with an estimated legal-sized biomass of 9,366 t [Ewing et al. 2021].

Scallop Area 3 opened to fishing in September 2021, the first season since 2015, with the TAC set at 1,494.9 t. However, there had been a major die-off post survey, most likely due to a warm-water incursion in the Flinders Island area and only 44.5 t was landed due to poor quality and recovery. The remainder of the Scallop Fishery Areas remained closed.

Surveys were again undertaken in 2022 and covered one north-west coast (western Bass Strait) bed (Scallop Fishery Area 1) with an estimated legal-sized (greater than 85 mm SL) biomass of 21,624 t and two lower east coast beds (Scallop Fishery Area 5) with an estimated legal-sized biomass of 16,608 t [Semmens et al. 2022].

Scallop Fishery Area 5 subsequently opened to fishing in late June 2022, with the TAC set at 3 495 t. However, again there had been a major die-off post survey and only 604 t was landed from this area due to predominately poor quality and poor recovery. However, Scallop Fishery Area 1 opened to fishing in early July under the established TAC, with a total of 2,793 t landed from that area. The TAC was increased in October to 4 495 t.  

Fishing mortality is managed with the aim of restricting catches to beds of mature scallops near the end of their lifespan. The combination of the harvest strategy and depleted biomass has led to a history of closures due to low abundance. In recent times, the fishery was closed between 2000–02 and again between 2009 and 2010. Areas with commercial density of scallops towards the end of their lifespan were opened to fishing each year between 2013–15. The fishery was subsequently closed again between 2016–20. However, surveys since 2020 have shown evidence of wide-scale recruitment that has occurred during the most recent closure period and fishing has occurred in 2021 and 2022, although this has been hampered somewhat by sudden bed die-off events in the eastern portion of the fishery, which may become more common with warming waters from the East Australian Current pushing further southward and predicted heatwave events.

On the basis that successful broadscale recruitment events during 2016–20 have increased biomass, and that current restrictions, particularly the new model of closing some biomass to fishing in the Scallop Fishery Area where fishing is taking place, are effectively limiting fishing mortality, the Tasmania Scallop Fishery management unit is classified as a recovering stock.

Commercial Scallop biology [Young et al. 1989; Woodburn 1990; Semmens et al. 2015; Ovenden et al. 2016]

Distribution of reported commercial catch of Commercial Scallop

Commonwealth – Commercial (Catch). Data provided for the Commonwealth align with the Commonwealth Bass Strait Central Zone Scallop Fishery for 2021.

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. Recreational fishing sectors in the Indian Ocean are South Australia, Victoria and Western Australia. Recreational sectors in the Pacific Ocean are New South Wales, Queensland and Tasmania.

Commonwealth – Indigenous. The Australian Government does not manage non-commercial Indigenous fishing in Commonwealth waters, with the exception of the Torres Strait. In general, non-commercial Indigenous fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters. Indigenous fishing sectors in the Indian Ocean are South Australia, Victoria and Western Australia.

Victoria – Commercial (Catch). (a) To protect commercial confidentiality of data, the catch in the Ocean Scallop Fishery (Victoria) and Port Phillip Bay Dive Scallop Fishery (Victoria) cannot be reported because there are fewer than five licence holders; and (b) In Victoria, the reporting period is fishing season, which runs from 1 April–30 March.

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. 

Commercial catch of Commercial Scallop - note confidential catch not shown

1. AFMA 2007, Harvest strategy for the Bass Strait Central Zone Scallop Fishery, Australian Fisheries Management Authority, Canberra.
2. AFMA 2012, Harvest strategy for the Bass Strait Central Zone Scallop Fishery, Australian Fisheries Management Authority, Canberra.
3. AFMA 2014, Harvest Strategy for the Bass Strait Central Zone Scallop Fishery, Australian Fisheries Management Authority, Canberra.
4. AFMA 2015, Harvest Strategy for the Bass Strait Central Zone Scallop Fishery, Australian Fisheries Management Authority, Canberra.
5. Bromhead, D, Blake, S and Curtotti, R, 2022, Bass Strait Central Zone Scallop Fishery, in Patterson, H, Bromhead, D, Galeano, D, Larcombe, J, Timmiss, T, Woodhams, J and Curtotti, R (eds), Fishery status reports 2022, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra.
6. Coleman, N 1998, Counting scallops and managing the fishery in Port Phillip Bay, south-east Australia, Fisheries Research, 38: 145–157.
7. Conron, SD, Bell, JD, Ingram, BA and Gorfine, HK 2020, Review of key Victorian fish stocks — 2019, Victorian Fisheries Authority Science Report Series No. 15, First Edition, November 2020, VFA, Queenscliff, 176 pp.
8. DEPI 2013, Commercial Scallop Dive Fishery (Port Phillip Bay) Baseline Management Arrangements, Fisheries Victoria, Melbourne.
9. Ewing, G, Moreno, D, Kilpatrick, R, Dudgeon, A and Semmens, J 2021, 2021 Tasmanian Scallop Fishery Pre Season Survey Report, Institute for Marine and Antarctic Studies, University of Tasmania.
10. Gwyther, D 2015, Review of The TACC For the Dive Fishery for Scallops in Port Phillip Bay – Report to Port Phillip Bay Scallops, 27 March 2015, Melbourne, Picton Group Pty Ltd, 6 pp.
11. Harrington, J, Leporati, S and Semmens, JM 2010, 2009 Victorian Scallop Fishery Survey, final report to Fisheries Victoria. Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Hobart.
12. Koopman, M, Knuckey, I and Hanley, M 2021, Eastern Victorian Ocean Scallop Fishery 2020 survey of “Tarwhine” scallop bed, Report to the Victorian Fisheries Authority, Fishwell Consulting, 9 pp.
13. Koopman, M, Knuckey, I and Hudson, R 2022, Eastern Victorian Ocean Scallop Fishery 2022 Pre-season Abundance Survey, Report to the Victorian Fisheries Authority, Fishwell Consulting, 39 pp.
14. Koopman, M, Knuckey, I and Hudson, R 2023, Eastern Victorian Ocean Scallop Fishery 2023 Pre-season Abundance Survey, Report to the Victorian Fisheries Authority, Fishwell Consulting, 28 pp.
15. Koopman, M, Knuckey, I, Harris, M and Hudson, R 2018, Eastern Victorian Ocean Scallop Fishery – 2017-18 Abundance Survey, Report to the Victorian Fisheries Authority, Fishwell Consulting, 42pp.
16. Ovenden, JR, Tillett, BJ, Macbeth, M, Broderick, D, Filardo, F, Street, R, Tracey, SR and Semmens, J 2016, Stirred but not shaken: population and recruitment genetics of the scallop (Pecten fumatus) in Bass Strait, Australia, ICES Journal of Marine Science, 73(9): 2333–2341.
17. Semmens, J, Ewing, G and Keane, J 2018, Tasmanian Scallop Fishery Assessment 2017, Institute for Marine and Antarctic Studies, 34 pp.
18. Semmens, JM and Jones, N 2012, Victorian scallop fishery survey final report, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart.
19. Semmens, JM, Ovenden, JR, Jones, NAR, Mendo, TC, Macbeth, M, Broderick, D, Filardo, F, Street, R, Tracey, SR and Buxton, CD 2015, Establishing fine-scale industry based spatial management and harvest strategies for the Commercial Scallop fishery in South East Australia, final report to the Fisheries Research and Development Corporation, project 2008/022, FRDC, Canberra.
20. Woodburn, L 1990, Genetic variation in southern Australian Pecten, in Proceedings of the Australasian Scallop Workshop, Tasmanian Government, Hobart.
21. Young, P and Martin, R 1989, The scallop fisheries of Australia and their management. Reviews in Aquatic Sciences, 1(4): 615–638.