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Gemfish is found throughout southern Australia. There are two genetically distinct national stocks. The western stock, harvested in WA and Commonwealth waters, is sustainable. The eastern stock, harvested in NSW and Commonwealth waters, is depleted.

There is genetic evidence for two biologically distinct stocks of Gemfish in Australia—an Eastern and a Western biological stock—separated by a boundary at the western end of Bass Strait [Colgan and Paxton 1997; Moore et al. 2017]. Studies suggest that there are no genetic differences between Gemfish in eastern Australia and New Zealand [Colgan and Paxton 1997]. For the purposes of assessment and management, the Eastern Australia population is treated as a single biological stock, independent of the New Zealand population.

Given the evidence of two genetically distinct stocks in Australian waters, stock status is reported accordingly. Here, assessment of stock status is presented at the biological stock level—Eastern and Western.

Eastern

Eastern Gemfish is primarily caught by the Commonwealth managed Southern and Eastern Scalefish and Shark Fishery (SESSF), with small catches from State jurisdictions. Stock status classification reported here is based on stock assessments conducted for the SESSF, which include reported State catches.

Eastern Gemfish in Commonwealth fisheries was managed as a Tier 1 stock under the SESSF Harvest Strategy Framework [AFMA 2021] but is currently managed under a rebuilding strategy [AFMA 2015] with an incidental catch allowance of 100 tonnes (t). In 2009, the species was listed as Conservation dependent under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

The last accepted quantitative stock assessment for Eastern Gemfish was published in 2010, using data up to 2009 [Little and Rowling 2010]. The base-case model estimated that the spawning stock biomass in 2009 was 16% of the unfished level. That assessment [Little and Rowling 2010] included projections of Eastern Gemfish biomass based on two scenarios: zero and 100 t (retained catch) each year. The projections for catches of zero and 100 t (retained catch) indicated that the spawning stock biomass may reach the limit reference point (LRP) of 20% of unfished level by 2017 and 2025, respectively, assuming average recruitment. A preliminary update of the 2010 assessment in 2016 [Little 2016], while not accepted by the South East Resource Assessment Group, indicated that the spawning stock biomass in 2015 had decreased to 8% of the unfished level, due to a prolonged period of below-average recruitment [AFMA 2016; Little 2016].

Recent research suggests that the spawning biomass in the eastern stock has fewer effective genetically successful contributors between generations [Moore et al. 2017; Ovenden et al. 2020]. The decreased effective population size in Eastern Gemfish may be related to few effective parents contributing to spawning each year or differential selection against recruits [Ovenden et al. 2020]. Contributors to the decreased effective population size of Eastern Gemfish are unclear, but climate and oceanographic conditions driving changes in species productivity, abundance and availability have been identified as potential factors inhibiting the recovery of overfished species in south-eastern Australia [Knuckey et al. 2018].

Commonwealth-landed catch in the Commonwealth Trawl Sector and Scalefish Hook Sector of the SESSF was 73.8 t in the 2021–22 fishing season, based on catch disposal records [Emery et al. 2022]. The weighted average of the previous 4 calendar years (2017–2020) was calculated and used to estimate discards and state catches of 44.1 t and 2 t, respectively [Althaus et al. 2021]. For the 2021–22 fishing season, total catch and discards were estimated to be 119.9 t.  

Commercial landings in New South Wales (NSW) have declined over the past decade from 11.1 t in 2012–13 to 0.7 t during 2021–22, with nearly all catch coming from the Ocean Trap and Line fishery. NSW landings represent a small proportion of annual fishing mortality. Anecdotal evidence, including photographs and reports on social media websites, indicates that Gemfish are targeted and captured by recreational anglers. However, surveys of recreational catch in NSW during 2019–20 [Murphy et al. 2022] and previous years [Murphy et al. 2020; West et al. 2015] detected no Gemfish captures. This suggests recreational catch is negligible, relative to commercial catch.

Commercial landings in Tasmania have been negligible, the maximum annual catch remaining below 100 kg, some years with no catch reported.

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

There are no reliable indicators to determine whether the current level of fishing mortality will allow the stock to rebuild to above the LRP in a time frame consistent with the requirements of the Commonwealth Harvest Strategy Policy. 

On the basis of the evidence provided above, the Eastern biological stock is classified as a depleted stock.

Gemfish biology [Hutchins and Swainston 1986; Rowling 1999]

Distribution of reported commercial catch of Gemfish

Commonwealth – Commercial (Management Methods/Catch) Data provided for the Commonwealth align with the Commonwealth Southern and Eastern Scalefish and Shark Fishery for the 2021–22 financial year. 

Commonwealth – Recreational The Commonwealth 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 – Indigenous The Australian government does not manage non-commercial Indigenous fishing in Commonwealth waters, with the exception of Torres Strait. In general, non-commercial Indigenous fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters.

New South Wales – Indigenous (Management Methods) Cultural Fishing Management Arrangements. See https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing.

New South Wales - Recreational (Catch) Catch estimate of “Negligible” is based zero catches of Gemfish recorded during the 2019–20 suvey of recreational catch by 1–3 year recreational licence holders in NSW [Murphy et al. 2022].

Commercial catch of Gemfish - note confidential catch not shown

1. AFMA 2010, Southern and Eastern Scalefish and Shark Fishery Great Australian Bight Resource Assessment Group (GABRAG) meeting, minutes, 12–14 October 2010, Adelaide, Australian Fisheries Management Authority, Canberra.
2. AFMA 2010, Southern and Eastern Scalefish and Shark Fishery Great Australian Bight Resource Assessment Group (GABRAG) meeting, minutes, 12–14 October 2010, Adelaide, Australian Fisheries Management Authority, Canberra.
3. AFMA 2015, Eastern gemfish (Rexea solandri) stock rebuilding strategy, Australian Fisheries Management Authority, Canberra.
4. AFMA 2016, Stock rebuilding strategies annual reviews. Eastern gemfish stock rebuilding strategy - annual review, South East Resource Assessment Group (SERAG) meeting 2016, Australian Fisheries Management Authority, Canberra.
5. AFMA 2021, Harvest strategy framework for the Southern and Eastern Scalefish and Shark Fishery: amended (2021), Australian Fisheries Management Authority, Canberra.
6. AFMA 2022, Southern and Eastern Scalefish and Shark Fishery species summaries 2022, Australian Fisheries Management Authority, Canberra.
7. AFMA 2022, Southern and Eastern Scalefish and Shark Fishery species summaries 2022, Australian Fisheries Management Authority, Canberra.
8. Althaus, F, Thomson, R and Sutton, C 2021, Southern and Eastern Scalefish and Shark Fishery catches and discards for TAC purposes using data until 2020, CSIRO Oceans and Atmosphere, Hobart.
9. Colgan, DJ and Paxton, JR 1997, Biochemical genetics and recognition of a western stock of the common Gemfish, Rexea solandri (Scombroidea: Gempylidae), in Australia, Marine and Freshwater Research, 48(2): 103–118.
10. Emery, T, Wright, D, Davis, K, Keller, K, Woodhams, J and Curtotti, R 2022, Commonwealth Trawl and Scalefish Hook sectors, 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.
11. Hutchins, B, and Swainston, R 1986, Sea fishes of southern Australia, Swainston Publishing, Perth.
12. Knuckey, I, Boag, S, Day, G, Hobday, A, Jennings, S, Little, R, Mobsby, D, Ogier, E, Nicol, S and Stephenson, R 2018, Understanding factors in influencing under-caught TACs, declining catch rates and failure to recover for many quota species in the SESSF, final report to the FRDC, project 2016/146, Fishwell Consulting, Queenscliff, Victoria.
13. Little, R 2016, Preliminary 2016 update of the eastern gemfish (Rexea solandri) stock assessment, CSIRO Oceans and Atmosphere, Hobart, Tasmania.
14. Little, R and Rowling, K 2010, 2010 update of the eastern gemfish (Rexea solandri) stock assessment, CSIRO Marine and Atmospheric Research and NSW Fisheries, Hobart, Tasmania.
15. Moore, A, Ovenden, J and Bustamante, C 2017, Research to underpin better understanding and management of western Gemfish stocks in the Great Australian Bight, FRDC project No. 2013/014, FRDC, Canberra.
16. Murphy, JJ, Ochwada-Doyle, FA, West, LD, Stark, KE and Hughes, JM 2020, The NSW Recreational Fisheries Monitoring Program – survey of recreational fishing, 2017/18, New South Wales Department of Primary Industries.
17. Murphy, JJ, Ochwada-Doyle, FA, West, LD, Stark, KE, Hughes, JM and Taylor, MD 2022, Survey of recreational fishing in NSW, 2019/20 – Key Results, NSW DPI – Fisheries Final Report Series No. 161, ISSN 2204-8669.
18. Ovenden, J, Davenport, D and Moore, A 2020, A perfect storm of genetic drift and divergence may prevent the rebuilding of the gemfish (Rexea solandri) stock on the east Australian coast, Fisheries Research, 230: 105645.
19. Rowling, K 1999, The fisheries biology and population dynamics of Gemfish Rexea solandri, PhD thesis, University of New South Wales, Sydney.
20. Sporcic, M 2019, Tier 4 Assessment for Western Gemfish (data to 2018), CSIRO Oceans and Atmosphere, Hobart.
21. West, L, Stark, KE, Murphy, JJ, Lyle, JM and Ochwada-Doyle, FA 2015, Survey of recreational fishing in New South Wales and the ACT, 2013–14, NSW Department of Primary Industries, Wollongong.