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The biological stock structure of Blue Morwong is unknown, although the its likely lengthy pelagic larval phase suggests considerable potential for individuals from geographically separated areas to mix. Assessments are presented here at the jurisdictional level. Stocks are classified as sustainable in WA, negligible in NSW and SA, and undefined with limited data in TAS and by the Commonwealth.

Photo credit: Chris Dowling.

Jurisdiction	Stock	Stock status	Indicators
Commonwealth	Commonwealth	Undefined	Catch
New South Wales	New South Wales	Negligible
South Australia	South Australia	Negligible
Tasmania	Tasmania	Undefined
Western Australia	Western Australia	Sustainable	Catch, catch distribution, catch rates, biology, length and age composition, fishing mortality, index of spawning stock biomass.

Blue Morwong's natural distribution is throughout the southern coastal waters of Australia's mainland. The stock structure is largely unknown. Its family, the Cheilodactylidae, typically have a pelagic larval phase lasting several months, facilitating transport over substantial distances. For Western Australia Coulson et al. [2010] suggested that as juveniles grow, substantial numbers move from the south coast to the lower west coast where they soon mature and spawn. Larvae are then transported south and then eastwards to the south coast, which is a juvenile nursery. Here assessment of stock status is presented at the jurisdictional level—Commonwealth, New South Wales, South Australia, Tasmania and Western Australia. 

Commonwealth

In Commonwealth Waters, Blue Morwong are largely taken in the area of the Great Australian Bight by sectors of the Southern and Eastern Scalefish and Shark Fishery (SESSF). Commonwealth commercial catch has averaged 20.3 tonnes (t) annually over the last ten financial years (2012–13 to 2021–22). In the 2021–22 financial year, 11.7 t were caught. No formal stock assessment has been conducted for this species in Commonwealth waters, however risk assessments undertaken indicate that the species is at low risk from fishing. Consequently, there is insufficient information available to confidently classify the status of this stock. On the basis of the information provided above, the Commonwealth jurisdictional stock is classified as an undefined stock.

New South Wales

Stock status for the New South Wales stock is reported as Negligible due to historically low catches in this jurisdiction and the stock has generally not been subject to targeted fishing. The New South Wales commercial catch in 2017–22 averaged approximately 1.2 t per annum, and Blue Morwong is not a major component of recreational landings. Fishing is unlikely to be having a negative impact on the stock.

South Australia

Stock status of Blue Morwong in South Australia is reported as Negligible due to historically low catches in this jurisdiction and the stock has not been subject to targeted fishing. South Australia’s commercial catch of Blue Morwong over the past 20 years has averaged 1.1 t per annum, and the species is not a major component of recreational landings. Fishing is unlikely to be having a negative impact on the stock.

Tasmania

In Tasmanian waters, catches of Blue Morwong are recorded by state authorities and the Commonwealth. Total catches average less than 0.1 t per year for the last decade, primarily representing records for the Tasmanian Scalefish Fishery and indicating that the species is not actively targeted but largely a by-product of gillnet fishing operations on the northern end of the east and west coasts. The maximum recorded total commercial catch was below 0.4 t in the 1999-2000 season. The species is unlikely to be targeted by recreational fishers and species-specific estimates of recreational catches are not available. Overall minor catches suggest that the species is at low risk from fishing, but no formal stock assessment has yet been conducted. The status of the Tasmanian stock of Blue Morwong is consequently undefined.

Western Australia

In Western Australia, Blue Morwong are taken mainly by the commercial demersal gillnet sector off the lower west and south coasts. The size selectivity of the net, coupled with the larger size reached by males, results in a higher level of fishing mortality for males. Catch-at-age sampling of 2,621 south coast Blue Morwong from the demersal gillnet and recreational sectors from 2012 to 2014 suggested regular and consistent recruitment for the previous two decades [Norriss et al. 2016]. The demersal gillnet sample (n = 1,234) from the eastern sub-region of the south coast was considered the most representative for an age-based stock assessment that allowed for length related selectivity. Two alternative methods were used to generate median estimates of female spawning potential ratio (SPR, the reproductive potential of the stock at the current level of fishing mortality compared to that at an unfished level, ± 95 per cent CI): SPR1 = 0.58 (0.46–0.71) and SPR2 = 0.54 (0.41–0.68), with an almost zero chance of breaching the threshold reference point (SPR=0.30) for either method. For males, SPR1 = 0.36 (0.25–0.51) and SPR2 = 0.34 (0.23–0.50) with a 19% and 31% chance of breaching the threshold reference point, respectively. There was an almost zero chance of males breaching the limit reference point (SPR=0.20). Estimates of natural mortality M (i.e., all sources of mortality other than fishing) were 0.22 (0.18–0.26) and fishing mortality F year^-1 was F_females = 0.106 (0.072–0.137) and F_males = 0.180 (0.123–0.231), yielding point estimates of F/M of 0.49 and 0.84 for females and males respectively. The probability of F breaching the threshold level (F/M = 1) was almost zero for females and 25% for males, and almost zero for either sex breaching the limit (F/M = 1.5).

The above evidence indicated that the biomass was unlikely to be unacceptably depleted at the time of the assessment, with only a slightly higher capacity for increased catches beyond recent historical levels before risk becomes unacceptable. Subsequent annual commercial south coast catches averaged 31 t during a period when fishing effort was declining [Braccini and Watt 2023], compared to the preceding decade’s average of 46 t. The total commercial catch in 2022 was 27 t and the statewide recreational boat catch in 2020–21 was 11 t (±2 se) [Ryan et al. 2022]. While there are no formal catch limits in place, recent catches are within the historic range and unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, the Western Australian jurisdictional stock is classified as a sustainable stock.

Blue Morwong biology. Blue Morwong from the south of Western Australia reach a maximum age of 24 years, are gonochorists (do not functionally change sex) with onset of sexual maturity at age 3 to 8 years at about 40 to 60 cm FL for females and 50 to 65 cm FL for males, with moderately fast growth (at age 5 years average total length was 55 cm for females and 58 cm for males) [Coulson et al. 2010; Norriss et al. 2016].

Species	Longevity / Maximum Size	Maturity (50 per cent)
Blue Morwong	24 years, 980 mm total length FL	Females: 3–8 years, 400–600 mm FL. Males 3–7 years, 500–650 mm FL.

Distribution of reported commercial catch of Blue Morwong.

	Commonwealth	Western Australia	New South Wales	Tasmania	South Australia
Commercial
Demersal Longline
Demersal Gillnet
Danish Seine
Otter Trawl
Hand Line, Hand Reel or Powered Reels
Line
Dropline
Gillnet
Fish Trap
Longline (Unspecified)
Hook and Line
Unspecified
Recreational
Spearfishing
Rod and reel
Charter
Hook and Line
Rod and reel

Method	Commonwealth	Western Australia	New South Wales	Tasmania	South Australia
Charter
Bag limits
License
Limited entry
Marine park closures
Size limit
Spatial closures
Temporal closures
Commercial
Effort limits
Effort limits (individual transferable effort)
Gear restrictions
Licence
License
Limited entry
Marine park closures
Size limit
Spatial closures
Spatial zoning
Recreational
Bag and possession limits
Fishing gear and method restrictions
Licence (Recreational Fishing from Boat License)
Marine park closures
Size limit
Spatial closures
Temporal closures

	Commonwealth	Western Australia	New South Wales	Tasmania	South Australia
Commercial	11.73t	28.51t	1.66t
Charter		2 t
Recreational		11.1 ± 1.8 t (se) (Boat based)

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 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.

Tasmania – Commercial (Catch). Catches reported for the Tasmanian Scalefish Fishery are for the period 1 July to 30 June the following year. The most recent assessment available is for 2021–22.

Tasmania – Recreational (Management Methods). A recreational licence is required for fishers using dropline or longline gear, along with nets, such as gillnet or beach seine. A minimum size limit of 250 mm is in place for all Morwong species other than Banded Morwong in Tasmanian waters. A bag limit of 10 fish and a possession limit of 20 fish (all Morwong species other than Banded Morwong) are also in place.

Tasmania - Indigenous (Management Methods). In Tasmania, Indigenous persons engaged in traditional fishing activities in marine waters are exempt from holding recreational fishing licences but must comply with all other fisheries rules as if they were licensed. For details, see the policy document 'Recognition of Aboriginal Fishing Activities” (https://fishing.tas.gov.au/Documents/Policy%20for%20Aboriginal%20tags%20and%20alloting%20an%20UIC.pdf). 

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

Commercial catch of Blue Morwong - note confidential catch not shown.

1. Braccini, M and Watt, M 2023, Temperate Demersal Gillnet and Demersal Longline Fisheries Resource Status Report, In: Status Reports of the Fisheries and Aquatic Resources of Western Australia 2021/22: The State of the Fisheries eds. Newman, S.J., Wise, B.S., Santoro, K.G. and Gaughan, D.J. Department of Primary Industries and Regional Development, Western Australia, pp. 227-232.
2. Coulson, PG, Hesp, SA, Hall, NG and Potter, IC 2010, Life cycle characteristics of the Blue Morwong Nemadactylus valenciennesi, compared with those of other species of Cheilodactylidae. Marine and Freshwater Research, 61: 104-118.
3. Hughes, JM, Murphy, JJ, Ochwada-Doyle, FA and Taylor, MD 2023, NSW Charter Fishery Monitoring 2019/20. NSW DPI - Fisheries Final Report Series No. 162.
4. Norriss JV, Fisher EA, Hesp SA, Jackson G, Coulson PG, Leary T, and Thomson, AW 2016, Status of inshore demersal scalefish stocks on the south coast of Western Australia. NRM Project 12034 Final Report. Fisheries Research Report, No. 276. Department of Fisheries, Western Australia, 116 pp.
5. Ryan, KL, Lai, EKM and 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.