I & I NSW Wild Fisheries research Program Grey ( douglasii)

Exploitation Status Overfished

Long term declines are evident in both landings and catch rates, and the average size of harvested fish has also decreased substantially since the 1970s. The age composition of landings strongly suggests that fishing mortality is greater than natural mortality.

Scientific name Standard name comment Formerly known as rubberlip morwong and Nemadactylus douglasii grey morwong blue morwong. Sometimes marketed as deep sea bream.

Nemadactylus douglasii Image © Bernard Yau

Background Grey morwong (Nemadactylus douglasii) are commonly caught near reefs at depths of distributed along the south-eastern Australian 10-100 m. Fish, crustaceans and invertebrates coastline in continental shelf waters from are the primary food items consumed by this Moreton Bay in Queensland to Wilsons’ species. The maximum length and weight of Promontory in Victoria. They can also be found grey morwong is approximately 80 cm and along the east coast of Tasmania to Storm Bay 6 kg, but the majority of fish caught are and are also present around the north island between 25 and 35 cm fork length (FL) in length of New Zealand, where they are known as and 250 to 500 g in weight. Catches contain ‘’. The common name of this species in very few fish greater than 50 cm in length. Australia has undergone a number of changes Grey morwong mature at 22 to 25 cm FL and in the past, and it has variously been known as spawning occurs between April and June. In rubberlip, blue and grey morwong, and is often common with other members of the family sold in retail outlets as ‘deep sea bream’. Cheilodactylidae, grey morwong probably have The biology and life history characteristics a pelagic ‘paperfish’ larval stage which may of grey morwong in Australian waters have last for many months. After settlement to their recently been studied. They are demersal fish demersal juvenile habitat, grey morwong reach

status of fisheries resources in nsw, 2008/09 Grey Morwong | p 163 wild fisheries research program

15cm FL after one year and 20 cm FL after two Catch years. A recent study (Stewart and Hughes, 2009) found that growth of individual grey Recreational Catch of Grey Morwong morwong was quite variable, but on average The annual recreational harvest of grey males appeared to grow faster that females. morwong in NSW is likely to lie between 130 There was also some evidence for variation in and 210 t. This estimate is based upon the recruitment strength from year to year. The results of the offsite National Recreational and oldest fish aged in this study was 22 years old, Indigenous Fishing Survey (Henry and Lyle, but few fish larger than 45 cm FL were available 2003) and onsite surveys undertaken by to be aged, so it is likely the longevity of grey I & I NSW. morwong is much greater than this.

In NSW grey morwong are taken by trap fishers Historical Landings of Grey Morwong in the Ocean Trap and Line Fishery along the whole coast and by fish trawl south of Smokey Cape. Grey morwong are a significant catch by recreational fishers in ocean waters. 800 600 Additional Notes 400 • Long term decline in the average size of Landings (t) landed fish indicates the stock is depleted. 200 • Size at maturity is below the current legal size

and the oldest fish sampled was aged 0

22 years - it is likely the maximum age is 78/79 83/84 88/89 93/94 98/99 03/04 08/09 greater. Financial Year Commercial landings (including available historical • The fishery is predominantly based upon age records) of grey morwong for NSW from 1978/79 to classes between 3 and 14 years old. 2008/09 for all fishing methods. • The age composition indicates variable recruitment. • The life-history characteristics of grey Landings by Commercial Fishery of Grey Morwong

morwong may make them susceptible to Ocean Trap and Line (Primary Species)

overfishing. These characteristics include Fish Trawl (Key Secondary Species) relatively slow growth rates, an extended pelagic larval phase and complex social interactions 150 • There are estimates of significant discarding

of small grey morwong by fish trawlers in the 100

early 1990s (Liggins, 1996). Landings (t)

• Length-based monitoring of commercial 50 catches is continuing at the Sydney Fish Market. 0 • There is a minimum legal length of 30 cm 97/98 99/00 01/02 03/04 05/06 07/08 total length and a recreational bag limit of 10 Financial Year grey morwong. Reported landings of grey morwong by NSW commercial fisheries from 1997/98. Fisheries which contribute less • The recreational harvest of grey morwong has than 2.5% of the landings are excluded for clarity and been estimated to be approximately 3 times privacy. the commercial harvest.

p 164 | Grey Morwong status of fisheries resources in nsw, 2008/09

Catch Per Unit Effort Information of Grey Morwong Length Frequency of Grey Morwong Harvested by Fish Trapping in NSW

1969/70−1989/90 0.10 1.0 n = 9881 0.08 0.8 0.06 0.6 Proportion 0.04 0.4 0.02 Relative Catch Rate 0.00 0.2

10 20 30 40 50 60 0.0

98/99 00/01 02/03 04/05 06/07 08/09 1997/98−2006/07

Financial Year 0.10 n = 7397 Catch rates of grey morwong harvested using fish trapping for NSW. Two indicators are provided: (1) 0.08 median catch rate (lower solid line); and (2) 90th

percentile of the catch rate (upper dashed line). Note that 0.06 catch rates are not a robust indicator of abundance in Proportion

many cases. Caution should be applied when interpreting 0.04 these results. 0.02 0.00 Growth Curve of Grey Morwong 10 20 30 40 50 60

●

● ● 50 2007/08−2008/09 ● 0.10 ● ● ● n = 2757 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.08 ● ● ● ● ●●

40 ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● 0.06 ● ● ● ● ●● ● ● ● ● ● ● ●●● ● ●● ● ● ● ● ● ● ● ● ● ●● ● ●● ● ● ● ●● ● ●●● ● ●●● ● ●● ●● ● ●● ● ● ● ● ● ● ● ● ● ● ● ●●●●●●●● ● ●● ●● ● ● ● ● ● ●●● ●● ●● ● ●● ● ● ● ●● ● ●●●● ●●●● ●● ● ● ● ● ● ●●●● ● ●● ●● ●● ● ● ● ● ●●●●●●●● ● ●●● ●●● ● ●● ● ● ●● ●●●●● ● ● Proportion ●● ●●● ●●● ● ●● ● ●● ● ●●● ● ●●●● ●● ●●● ● ●● ● ● ● ● ● ● ● ● ● ● 0.04 30 ● ● ●● ● ● ● ● ● FL (cm) ● ● ●● ●●● ● ● ●● ● ●●●●●●●●●●●●● ● ●● ● ●● ●● ● ● ●●● ●● ● ● ●●● ●● ● ● ● ●●●● ● ●●● ● ● ●●●●●● ●●● ● ● ●● ● ● ● ● ●● ● ●●●● ●● ●●● ● ● ●● ●●● ●●● ● ● ● ●●●● ●●●● ●● ● ● ●● ●●● ● ● ●●●● ●●● ●● ●●●● ● ● ● ●●●●● ● ● ● ●●●●●●●● ● ●

● ● ● 0.02 ● ● ●●● ●●●● ● ● ●●●●● ● ●● ●● ●● ●● ●● ● ●●● ● ● ●●● ●●●●● ●●●● 20 ●●●● ●● ● ● ● 0.00 ● ● 10 20 30 40 50 60

● FL (cm) 10 0 5 10 15 20 The proportion of larger (>40 cm fork length (FL)) grey Age (years) morwong in commercial landings declined between the 1970s and the 1990s and recent landings have mainly Age-length data with fitted growth curve for grey comprised fish between 25 and 40 cm FL. The minimum morwong (Stewart and Hughes, 2008). Lengths are legal length of grey morwong in NSW was increased from presented as fork length (FL). 28 to 30 cm total length in September 2007.

Grey Morwong | p 165 wild fisheries research program

Further Reading Henry, G.W. and J.M. Lyle (2003). The National Recreational and Indigenous Fishing Survey. Final Report to the Fisheries Research & Development Corporation and the Fisheries Action Program Project FRDC 1999/158. NSW Fisheries Final Report Series No. 48. 188 pp. Cronulla, NSW Fisheries. Liggins, G.W. (1996). The interaction between fish trawling (in NSW) and other commercial and recreational fisheries. Final Report, FRDC Project 92/79. Cronulla, NSW Fisheries. Lowry, M. and M. Cappo (1999). Morwong, In Under southern seas: the ecology of Australia’s rocky reefs. N. Andrew, (Eds.) Sydney, University of NSW Press: 238 pp. Steffe, S., J. Murphy, D. Chapman, B.E. Tarlington, G.N.G. Gordon and A. Grinberg (1996). An assessment of the impact of offshore recreational fishing in New South Wales on the management of commercial fisheries. Project 94/053. Sydney, NSW Fisheries Research Institute: 139 pp. Stewart, J. and D.J. Ferrell (2003). Mesh selectivity in the NSW demersal trap fishery, Fisheries Research 59: 379-392. Stewart, J. and J.M. Hughes (2008). Determining appropriate sizes at harvest for species shared by the commercial trap and recreational fisheries in New South Wales. FRDC Project No. 2004/035. Fisheries Final Report Series No.97. Cronulla, NSW Department of Primary Industries: 282pp. Stewart, J. and J.M. Hughes (2009). Biological and fishery characteristics of rubberlip morwong Nemadactylus douglasii (Hector, 1875) in eastern Australia. Fisheries Research 96 (2-3): 267-274.

Please visit the CSIRO website, http://www.marine.csiro.au/caab/ and search for the species code (CAAB) 37 377002, common name or scientific name to find further information.

© State of New South Wales through Industry and Investment NSW 2010. You may copy, distribute and otherwise freely deal with this publication for any purpose, provided that you attribute Industry and Investment NSW as the owner.

Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (April 2010). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of Industry and Investment NSW or the user’s independent adviser. p 166 | Grey Morwong