Blue Morwong (2020)
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The biological stock structure of Blue Morwong is unknown, although the its 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.
Stock Status Overview
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.  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.
In Tasmanian waters, catches of Blue Morwong are recorded by state authorities and the Commonwealth. Total catches average only about 0.1 t per year, 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 coast. The maximum recorded total commercial catch was below 0.4 t in the 1999–00 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.
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)|
24 years, 98 cm total length
Females: 3–8 years, 400–600 mm FL. Males 3–7 years, 500–650 mm FL.
Distribution of reported commercial catch of Blue Morwong.
|Bag and possession limits|
|Fishing gear and method restrictions|
|Marine park closures|
New South Wales – Indigenous (Management Methods) https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing
New South Wales – Recreational (Catch) Murphy et al. .
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 2018/19.
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://dpipwe.tas.gov.au/Documents/Policy%20for%20Aboriginal%20tags%20and%20alloting%20an%20UIC.pdf).
Commercial catch of Blue Morwong - note confidential catch not shown.
- Coulson, P.G., Hesp, S.A., Hall, N.G. and Potter, I.C. (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.
- Murphy, J.J., Ochwada-Doyle, F.A., West, L.D., Stark, K.E. and Hughes, J.M., 2020. The NSW Recreational Fisheries Monitoring Program - survey of recreational fishing, 2017/18. NSW DPI - Fisheries Final Report Series No. 158.
- 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.
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