*

The long-lived Mangrove Jack is classified as sustainable in WA, recovering in the Gulf of Carpentaria and undefined in the NT and East Coast QLD. Stock status is negligible in NSW.

Mangrove Jack are a long lived (> 50 years), late maturing species that can reach a length of over 1 m [Russell et al. 2003]. They are broadly distributed throughout the tropical and sub-tropical Indo-West Pacific [Allen 1985] and exhibit a biphasic life history pattern, where juveniles spend several years in freshwater and estuarine habitats before migrating offshore as they near sexual maturity, and have been reported to a depth of at least 175 m [Pradella et al. 2013].

The distribution of this species within Australian waters extends from approximately Perth, Western Australia, around the north of the continent to Sydney, New South Wales [Pember et al. 2005, Russell et al. 2003]. Genetic analyses indicate that Mangrove Jack consist of a single biological stock across its Australian range [Russell et al. 2003]. This level of mixing is consistent with a life history that involves offshore spawning by adults. However, Mangrove Jack experience moderate to high harvest rates in some Australian fisheries (particularly those targeting adults of this long-lived species), which may cause localised depletion. While juvenile fish have been shown to migrate from freshwater and estuarine habitats to offshore reef environments, often with a movement component of up to 335 km [Russell et al. 2003], once these ontogenetic movements have occurred there have been no reports of adult fish undertaking extensive movements, although studies are limited. As such, limited evidence of adult movement in combination with evidence of varying stock status in different regions indicates that Mangrove Jack likely comprise separate management units.

Here, assessment of stock status is presented at the management unit level―East Coast Queensland and the Gulf of Carpentaria; and at the jurisdictional level―Western Australia, Northern Territory and New South Wales.

East Coast Queensland

Mangrove Jack is taken as a minor by-product species in Queensland commercial line and net fisheries - the Coral Reef Finfish Fishery (CRFFF) and the East Coast Inshore Finfish Fishery (ECIFFF). Catch of Mangrove Jack in the commercial line (1.9 t in 2018–19) and net (1.1 t in 2018–19) fisheries is stable and has averaged 2.5 t in total since 2010–11 [QFISH 2020].  Catch rates for the commercial net and line fishery are not considered to be reliable indicators of biomass because this species is not commercially targeted within this management unit.

There is a significant recreational fishery for this species (average 62 t from 2000 to 2019) [Teixeira et al. 2021], but the Indigenous catch is considered to be low. Mangrove Jack is a popular recreational species in all habitats they occupy but considered to be difficult to target. The MLS is less than the size at maturity and preliminary fishery-dependent monitoring has documented a majority (> 90 per cent in 2017) of recreationally caught‑ fish are less than the size at maturity (L₅₀ for females) [DAF unpublished data]. The impact of this on the stock is unknown. A portion of the biomass is not available to the fishery because of state marine parks and the Great Barrier Reef Marine Park (GBRMP) although the proportion protected has not been quantified. There is insufficient information available to confidently classify the status of this stock.

On the basis of the evidence provided above, the management unit is classified as an undefined stock.

Gulf of Carpentaria

Mangrove Jack were exposed to foreign trawling activity between 1950 and 1990 [O'Neill et. al. 2011] with catches being slightly lower than contemporary harvests. During 2002–2011 the Gulf of Carpentaria Developmental Fin Fish Fishery (GOCDFFTF) harvest averaged approximately 50 t which was considered higher than the 30 t MSY identified in a previous assessment [O’Neill et al. 2011]. Since 2012–13, effort has been absent or very low in the GOCDFFTF but has increased to above 40 t in the Northern Territory Demersal Fishery (DF) in 2019. Mangrove Jack in the GOC have been previously considered to be recovering from overfishing due to the MSY being exceeded. The current assessment uses a modified catch-MSY model (developed by Martell and Froese [2013] and modified by Haddon et al. [2018]) and uses data from both Queensland and Northern Territory. The outputs from the model estimated that the 2019 biomass of Mangrove Jack in the GOC was 56 per cent of unfished levels [Saunders and Roelofs 2020] suggesting that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Similarly, the model estimated that the fishing mortality (0.1) in 2019 was well below the limit point indicating that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, the management unit is classified as a sustainable stock.

Mangrove Jack biology [Pember et al. 2005, Piddocke et al. 2015, Russell et al. 2003]

Distribution of reported commercial catch of Mangrove Jack

Western Australia Active Vessels data is unreportable as there were fewer than three vessels operating in Pilbara Fish Trawl Interim Managed Fishery and Pilbara Trap Managed Fishery.

Western Australia – Recreational (Catch) Boat-based recreational catch is from 1 September 2017–31 August 2018. These data are derived from those reported in Ryan et al. [2019]. Shore based catches of Mangrove Jack are not known.

Western Australia – Recreational (management methods) A Recreational Fishing from Boat License 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.

Northern Territory Recreational Catch from West et al. [2012].

Queensland – Indigenous (management methods) for more information see https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

1. 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. 35p.
2. FAO species catalogue, volume 6, snappers of the world. FAO Fisheries Synopsis 125.
3. Gulf of Carpentaria Mangrove Jack Stock Status Summary - 2020. Unpublished Fishery Report
4. Haddon M, Punt A and Burch P 2018, simpleSA: A package containing functions to facilitate relatively simple stock assessments. R package version 0.1.18.
5. Martell, S, and Froese, R. 2013, A simple method for estimating MSY from catch and resilience. Fish and Fisheries 14:504–514.
6. 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.
7. Newman, SJ, Wakefield, C, Skepper, C, Boddington, Blay, N 2020. North Coast Demersal Resource Status Report 2019. pp. 158–168. In: Gaughan, D.J. and Santoro, K. (eds.) 2020. Status Reports of the Fisheries and Aquatic Resources of Western Australia 2018/19: The State of the Fisheries. Department of Primary Industries and Regional Development, Western Australia, Perth, Australia. 291p.
8. Northern Territory Mangrove Jack Stock Status Summary - 2020. Unpublished Fishery Report
9. O’Neill, MF, Leigh, GM, Martin, JM, Newman, SJ, Chambers, M, Dichmont, CM and Buckworth, RC 2011, Sustaining productivity of tropical red snappers using new monitoring and reference points, The State of Queensland, Department of Employment, Economic Development and Innovation, Brisbane, Queensland.
10. Pember MB, Newman SJ, Hesp SA, Young GC, Skepper CL, Hall NG and Potter IC 2005, Biological parameters for managing the fisheries for Blue and King Threadfins, Estuary Rockcod, Malabar Grouper and Mangrove Jack in north-western Australia. Final Report to the Fisheries Research and Development Corporation (FRDC) on Project No. 2002/003. Centre for Fish and Fisheries Research, Murdoch University, Murdoch, Western Australia, Australia. 172p.
11. Piddocke, TP, Butler, GL, Butcher, PA, Stewart, J, Bucher, DJ and Christidis, L 2015, Age and growth of mangrove red Snapper Lutjanus argentimaculatus at its cool-water-range limits, Journal of Fish Biology, 86, 1587–1600.
12. Pradella, N, Fowler, AM, Booth, DJ, Macreadie, PI 2013. Fish assemblages associated with oil industry structures on the continental shelf of north-western Australia. Journal of Fish Biology, 84(1): 247–255.
13. QFish, Department of Agriculture and Fisheries, www.qfish.gov.au
14. Russell, DJ, McDougall, AJ, Fletcher, AS, Ovenden, JR and Street, R 2003, Biology, management and genetic stocks structure of mangrove jack (Lutjanus argentimaculatus) in Australia. FRDC Project Number 1999/122, Department of Primary Industries, Queensland and the Fisheries Research Development Corporation, Brisbane.
15. Ryan KL, Hall NG, Lai EK, Smallwood CB, Tate, A, Taylor SM, Wise BS 2019, Statewide survey of boat-based recreational fishing in Western Australia 2017/18. Fisheries Research Report No. 297. Department of Primary Industries and Regional Development, Government of Western Australia, Perth. 
16. Teixeira, D., Janes, R. and Webley, J. (2021) 2019/20 Statewide Recreational Fishing Survey Key Results. Project Report. State of Queensland, Brisbane. In press.
17. Webley, J, McInnes, K, Teixeira, D, Lawson, A, Quinn, R 2015, Statewide Recreational Fishing Survey 2013–14, Queensland Department of Agriculture and Fisheries, Brisbane.
18. West, LD, Lyle, JM, Matthews, SR and Stark, KE 2012, A survey of recreational fishing in the Northern Territory, 2009–10, Fishery report 109, Northern Territory Government Department of Resources, Darwin.