*

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

ACL

Aboriginal Coastal License (NT)

CLF

Coastal Line Fishery (NT)

DF

Demersal Fishery (NT)

TRF

Timor Reef Fishery (NT)

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 can 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 different 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―Queensland Gulf of Carpentaria and East Coast Queensland; and at the jurisdictional level―Western Australia, Northern Territory and New South Wales.

Northern Territory

Mangrove Jack is a highly regarded fish in the Northern Territory but is one of the less common Lutjanids in this jurisdiction. Almost all Mangrove Jack caught by recreational fishers in the Northern Territory are harvested from estuarine and inshore habitats [West et al. 2012], whereas the majority of the commercial harvest (by the multi-species Timor Reef and Demersal Fisheries) occurs offshore.

The magnitude of the recreational harvest of this species is around 5 per cent of the commercial catch (derived from West et al. [2012] using a regional weight multiplier of 0.8 kg per fish, and contemporary commercial catch data). There are no estimates of the Indigenous harvest of Mangrove Jack in the Northern Territory. The lack of a long-term time series on recreational and Indigenous catches means that the assessment presented here is based on data from commercial logbooks.

The average annual commercial catch of Mangrove Jack in the Northern Territory for the decade spanning 2008–17 was 32 t. A preliminary assessment of this species using SimpleSA [NTG unpublished] indicates that the biomass of the stock is above the target biomass (at ≥ 50 per cent of 1983 biomass) but that fishing mortality rate from 2015–17 may have exceeded the target harvest rate (at 0.19 per annum). However, the level of uncertainty around these model outputs is too wide to make an informed judgement on the status of the stock. This uncertainty arises from the fact that Mangrove Jack is not actively targeted by the Timor Reef Fishery or the Demersal Fishery and because these fisheries have only scaled up in recent years. Hence, there is insufficient information available to confidently classify the status of this stock.

On the basis of the evidence provided above, Mangrove Jack in the Northern Territory is classified as an undefined stock.

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

Distribution of reported commercial catch of Mangrove Jack

ACL

Aboriginal Coastal License (NT)

CLF

Coastal Line Fishery (NT)

DF

Demersal Fishery (NT)

TRF

Timor Reef Fishery (NT)

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 2015–31 August 2016. These data are derived from those reported in Ryan et al. [2017]. 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 Subject to the defence that applies under 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 Commercial catch from 1 July 2016–30 June 2017.

Queensland – Recreational (catch) Survey of Queensland residents only from August 2013–October 2014 [Webley et al. 2015].

Queensland – Indigenous Under the Fisheries Act 1994 (Qld), Indigenous fishers in Queensland are entitled to use prescribed traditional and non-commercial fishing apparatus in waters open to fishing. Size and possession limits, and seasonal closures do not apply to Indigenous fishers. Further exemptions to fishery regulations may be applied for through permits.

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. 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.
4. Newman, SJ, Wakefield, C, Skepper, C, Boddington, D, Jones, R and Smith, E 2018. North Coast Demersal Resource Status Report 2017. pp. 127–133. In: Gaughan, D.J. and Santoro, K. (eds.). Status Reports of the Fisheries and Aquatic Resources of Western Australia 2016/17: The State of the Fisheries. Department of Primary Industries and Regional Development, Western Australia, Perth, Australia. 237p.
5. 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.
6. 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.
7. 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.
8. 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.
9. Queensland Department of Agriculture and Fisheries 2018, Queensland Stock Status Assessment Workshop Proceedings 2018. Species Summaries. 19–20 June 2018, Brisbane.
10. 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.
11. Ryan KL, Hall NG, Lai EK, Smallwood CB, Taylor SM, Wise BS 2017, Statewide survey of boat-based recreational fishing in Western Australia 2015/16. Fisheries research Report No. 287. Department of Primary Industries and Regional Development, Government of Western Australia, Perth. 
12. Webley, J, McInnes, K, Teixeira, D, Lawson, A, Quinn, R 2015, Statewide Recreational Fishing Survey 2013–14, Queensland Department of Agriculture and Fisheries, Brisbane.
13. 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.