*

Ruby Snappers are widely distributed throughout northern Australian waters. There are two biological stocks. The Northern Australia stock encompasses all Australian waters west of Torres Strait (i.e. waters off the NT and WA), while the Eastern Australian stock occurs off the east coast of QLD, extending south into NSW. The Northern Australia stock is sustainable, while the Eastern Australia stock is currently undefined, although the level of catch is very low.

Photo: Stephen Newman, Department of Primary Industries and Regional Development, Western Australia

Andrews et al. [2016] examined the phylogeny of deepwater snappers of the genus Etelis using two mtDNA loci and two nuclear introns. The analyses of Andrews et al. [2016] indicated that species identified as Etelis carbunculus is comprised of two distinct, non-interbreeding lineages separated by a deep divergence, i.e., it was comprised of two cryptic species, E. carbunculus and a larger Etelis boweni (described by Andrews et al. 2021). Both cryptic species exhibit overlapping Indo-Pacific distributions, with E. carbunculus being more widespread across the Indo-Pacific, whereas the larger E. boweni is reported mainly from the Indian Ocean and Western Central Pacific [Andrews et al. 2016]. While these two species are morphologically similar, there are differences in the coloration of the upper-caudal fin tip, the shape of the opercular spine, differences in adult body length, body depth, and head length, and otolith morphometrics that can be used to separate the species [Wakefield et al. 2014; Andrews et al. 2016]. These species are now commonly referred to as pygmy ruby snapper (E. carbunculus) and giant ruby snapper (E. boweni). The main species landed in northern Australian waters is E. boweni [Andrews et al. 2021]. 

Andrews et al. [2020] investigated the population structure of E. carbunculus and E. boweni (as well as Etelis coruscans) across their distributional range in the Indo-Pacific. Andrews et al. [2020] examined a total of 1,064 specimens of E. carbunculus from 11 regions, and 590 specimens of E. boweni from 16 regions. Samples of E. carbunculus were analysed using mtDNA and 9–11 microsatellite loci, while E. boweni was analysed with mtDNA only. Etelis carbunculus exhibited low but significant levels of isolation for the Hawaiian Archipelago, and divergence between Tonga and Fiji. Etelisboweni exhibited little structure except a strong pattern of isolation for both Seychelles and Tonga at the edge of their distribution (east and west, respectively). This indicates populations are structured on the wider scale of ocean basins and the capacity for widespread dispersal throughout the Indo-Pacific region. As such, Australian populations of Ruby Snappers are likely to form a single biological stock in the Western Pacific area (east coast) and the eastern Indian Ocean area (west coast). 

Here, assessment of stock status of Ruby Snappers is presented at the biological stock level—Northern Australia (Western Australia, Northern Territory, Commonwealth, Queensland); and Eastern Australia (Queensland, Commonwealth, New South Wales).

Northern Australia

The assessment of the stock status of Ruby Snapper in Northern Australia is based on an assessment of the relative contributions of catch from each jurisdiction and a formal assessment using a catch curve and per-recruit analyses based on age composition data of E. boweni in Western Australia. The Ruby Snapper complex comprises two species, E. carbunculus (pygmy ruby snapper) and E. boweni (giant ruby snapper) [Wakefield et al. 2014]. These two cryptic species are sympatric and typically co-occur in catches throughout their distribution. The main species landed in northern Australian waters is E. boweni. Ruby snappers in North Western Australia are landed predominately by commercial line fishers in the Pilbara Line Fishery, Gascoyne Demersal Scalefish Managed Fishery, West Coast demersal Scalefish (Interim) Managed Fishery and in small quantities by trap fishers in Northern Demersal Scalefish Managed Fishery and the Commonwealth's Western Deepwater Trawl Fishery.  The Giant Ruby Snapper is one of the indicator species for North Western Australia [Newman et al. 2018] and as such the stock status of Ruby Snapper contributes to determining the risk-level for the biological sustainability of the deep water demersal scalefish resources in North Western Australia. An assessment using catch curve and per-recruit analyses based on representative age composition data of Giant Ruby Snapper has also been undertaken for North Western Australia. Fishing mortality based estimates are assessed relative to reference levels based on ratios of natural mortality [DPIRD 2017]. Assessment models are also used to estimate a female spawning potential ratio (SPR, based on female spawning biomass per recruit) using a traditional per-recruit model assuming constant recruitment (SPR). In the absence of a direct estimate of B_MSY for the stock, the estimates of SPR for females in 1997 and 2011 were compared to a proxy reference level based on a proportion of the unfished spawning biomass, B₀. Where 0.3 B₀ is considered a proxy threshold level for State-managed Western Australian fisheries and is consistent with B_MSY estimates [Wakefield et al. 2020]. This assessment of Giant Ruby Snapper is supported by predictions for biomass and harvest rates from a data-limited Catch-MSY assessment model compared periodically to a median model estimate for maximum sustainable yield (MSY). 

The stock assessment for Giant Ruby Snapper (Etelis boweni) in the North Western Australia region of Northern Australia is based on an assessment of fishing mortality derived from catch curve analysis of representative samples of the age structure [Wakefield et al. 2020]. Point estimates of fishing mortality (F = 0.038 [1997] and 0.052 year[-1] [2011]) and associated confidence limits were well below the value for natural mortality (M) of 0.11 year[-1], indicating that, on average over the life span of the fish in the samples, exploitation has been relatively low. Estimates of mortality and selectivity from 1997 and 2011, and analyses of the female relative spawning potential ratio suggest the Etelis boweni stock in North Western Australia region has remained at around 60% of the unfished level over the years represented by the age composition sample [Wakefield et al. 2020]. Given that this species is longer lived than E. carbunculus [see Williams et al. 2017] and is more dominant in catches, the status of this species is considered to represent the status of Ruby Snappers in the Northern Australia stock. Catches across the distributional range of Etelis boweni are low. 

The total catch of Ruby Snappers in WA have been variable over the last 10 years (2013–2022), ranging from 15.4–41.7 t, with a mean annual catch of 28.5 t. This is considerably lower than the average catches across the previous 10 years of 69.6 t. The recreational and charter catch are relatively low compared to the commercial catch, in the past 10 years where reliable catches estimates are available, the proportion of the total catch has averaged 25%. The Commonwealth commercial catch in the Western Deepwater Trawl Fishery, operating off the West Australian Coast has been variable over the last decade (2012–13 to 2021–22 financial years), ranging from 0 to 21 t (5 t in 2021–22; 2 t in 2020–21). Analyses using a Catch-MSY model applied to data on annual catches for this species (1993–2022) in Western Australia, demonstrated that the annual catches since 2013 have remained below the median model estimate for maximum sustainable yield (MSY), after having been above the 95% CI of MSY for the period of 2001–2012. This is also consistent with the predicted values for biomass increasing in recent years to just below B_MSY, and fishing mortality remaining below F_MSY. However, it is important to recognise that Catch-MSY is a data-limited technique with relatively strong assumptions, dependent on user inputs. For this assessment, these included specified ranges for initial depletion (0.8–0.975), based on the late development of the deep water fishery and the species are not exploited continually across the entire distribution, final depletion (0.15–0.7), based on recent catches relative to maximum recorded annual catch and the non-targeted nature, and low resilience (r=0.1–0.6, consistent with species longevity, of ~32 years). For the Northern Territory part of the management unit, only relatively small catches are recorded in the Timor Reef fishery. Targeting of Ruby snappers by this fishery is constrained by the fact that this species distribution largely resides outside of the fishery boundary. As a result, during the period 2013–2022 the average annual catch by this fishery was less than 2.5 t.  Additionally, the offshore distribution of Ruby Snapper in NT waters means that the recreational and Fishing Tour Operator landings are likely to be insignificant. Commercial harvest of Ruby Snapper in the eastern Gulf of Carpentaria is managed as part of the ‘other species’ quota category in the GOCDFFTF (largely inactive since 2016), which comprises other reef finfish species. Ruby Snapper is also commercially harvested by the GOCLF where there are no caps on total catch at the species or complex level. Catch has not been recorded in either Queensland fishery since 2008, when a total of 8.3 t was recorded. The above evidence indicates that the biomass of Ruby Snappers is unlikely to be depleted, and the current level of fishing mortality is unlikely to cause the stock of Ruby Snappers to become recruitment impaired. 

On the basis of the evidence provided above, the Ruby Snappers species group in north-western region of Northern Australia is classified as a sustainable stock.

Ruby Snappers biology [Wakefield et al. 2020]

Distribution of reported commercial catch of Ruby Snappers

Western Australia – Recreational (Catch). Boat-based recreational catch is from 1 September 2020–31 August 2021. These data are derived from those reported in Ryan et al. 2022.

Western Australia – Recreational (Management Methods). A Recreational Fishing from Boat Licence is required for the use of a powered boat to fish or to transport catch or fishing gear to or from a land-based fishing location.

Western Australia – Indigenous (Management Methods). Subject to application of Section 211 of the Native Title Act 1993 (Cth), and the exemption from a requirement to hold a recreational fishing licence, the non-commercial take by Indigenous fishers is covered by the same arrangements as that for recreational fishing.

New South Wales – Recreational (Catch). Murphy et al. [2022].

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

Queensland – Indigenous (Management Methods). For more information see: https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

Queensland – Commercial (Catch). Queensland commercial and charter data have been sourced from the commercial fisheries logbook program. Further information available through the Queensland Fisheries Summary Report: https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/data/queensland-fisheries-summary-report

Queensland – Recreational Fishing (Catch). Data with high uncertainty (Residual Error > 50 %) has been excluded and listed as unknown. More information available at: https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/monitoring-reporting/statewide-recreational-fishing-surveys

Queensland – Commercial (Management Methods). Harvest strategies available at: https://www.daf.qld.gov.au/business-priorities/fisheries/sustainable/harvest-strategy

Northern Territory – Charter (Management Methods). In the Northern Territory, charter operators are regulated through the same management methods as the recreational sector but are subject to additional limits on license and passenger numbers.

Northern Territory - Indigenous (Management Methods). The Fisheries Act 1988 (NT), specifies that: “Unless expressly provided otherwise, nothing in this Act derogates or limits the right of Aboriginal people who have traditionally used the resources of an area of land or water in a traditional manner to continue to use those resources in that area in that manner.”

Commonwealth – Commercial (Management Methods/Catch). Data provided for the Commonwealth align with 2021–22 financial year.

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 – 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.

Commercial catch of Ruby Snappers - note confidential catch not shown

1. Andrews, KR, Copus, JM, Wilcox, C, Williams, AJ, Newman, SJ, Wakefield, CB and Bowen, BW 2020, Range-wide population structure of three deepwater Eteline snappers across the Indo-Pacific basin. Journal of Heredity
2. Andrews, KR, Williams, AJ, Fernandez-Silva, I, Newman, SJ, Copus, JM, Wakefield, CB, Randall, JE, and Bowen, BW 2016, Phylogeny of deepwater snappers (Genus Etelis) reveals a cryptic species pair in the Indo-Pacific and Pleistocene invasion of the Atlantic. Molecular Phylogenetics and Evolution 100: 361-371.
3. DPIRD 2017, North Coast demersal scalefish resource harvest strategy 2017 – 2021, Version 1.0, Fisheries Management Paper No. 285, Department of Primary Industries and Regional Development, Government of Western Australia, Perth, Australia, 35 pp.
4. Murphy, JJ, Ochwada-Doyle, FA, West, LD, Stark, KE,Hughes, JM and Taylor, MD 2022, Survey of recreational fishing in NSW, 2019/20. NSW DPI - Fisheries Final Report Series No. 161.
5. Newman, SJ, Brown, JI, Fairclough, DV, Wise, BS, Bellchambers, LM, Molony, BW, Lenanton, RCJ, Jackson, G, Smith, KA, Gaughan, DJ, Fletcher, WJ, McAuley, RB and Wakefield, CB 2018, A risk assessment and prioritisation approach to the selection of indicator species for the assessment of multi-species, multi-gear, multi-sector fishery resources. Marine Policy, 88: 11–22.
6. Queensland Department of Agriculture and Fisheries 2020, Reef line fishery harvest strategy: 2020–2025. Brisbane, Queensland.
7. Ryan KL, Lai EKM, Smallwood CB. 2022. Boat-based recreational fishing in Western Australia 2020/21. Fisheries Research Report No. 327 Department of Primary Industries and Regional Development, Western Australia. 221pp.
8. Teixeira, D, Janes, R, and Webley, J 2021, 2019–20 Statewide Recreational Fishing Survey Key Results. Project Report. State of Queensland, Brisbane.
9. Wakefield, CB, Williams, AJ, Fisher, EA, Hall, NG, Hesp, SA, Halafihi, T, Kaltavara, J, Vourey, E, Taylor, BM, O'Malley, JM, Nicol, SJ, Wise, BS and Newman, SJ 2020, Variations in life history characteristics of the deep-water giant ruby snapper (Etelis sp.) between the Indian and Pacific Oceans and application of a data-poor assessment, Fisheries Research 230 (105651)
10. Wakefield, CB, Williams, AJ, Newman, SJ, Bunel M, Dowling, CE, Armstrong, CA and Langlois, TJ 2014, rapid and reliable multivariate discrimination for two cryptic Eteline snappers using otolith morphometry, Fisheries Research 151: 100–106
11. Williams, AJ, Wakefield, CB, Newman, SJ, Vourey, E, Abascal, FJ, Halafihi, T, Kaltavara, J and Nicol, SJ.2017, Oceanic, latitudinal, and sex-specific variation in demography of a tropical deepwater snapper across the Indo-Pacific region. Front Mar Sci. 4: 382.