I & I NSW WILD FISHERIES RESEARCH PROGRAM Jackass Morwong (Nemadactylus macropterus) EXPLOITATION STATUS OVERFISHED The commercial harvest is predominantly by trawlers in the Commonwealth Southern and Eastern Scalefish and Shark Fishery. Commonwealth assessment is based on a full population model which shows a very significant decline in biomass since the 1980s. The biomass has recently been estimated to be about 20% of the unexploited level. SCIENTIFIC NAME STANDARD NAME COMMENT Nemadactylus macropterus jackass morwong Nemadactylus macropterus Image © Bernard Yau Background 10 - 13 cm fork length (FL). Maximum lengths observed were 43 cm FL for males and The worldwide distribution of jackass morwong 46 cm FL for females. Growth of juveniles is (Nemadactylus macropterus) includes waters rapid with fish attaining a size of about 26 cm at of New Zealand, southern South America, 3 years of age. After fish reach sexual maturity southern Africa and some islands in the Atlantic at 4 to 5 years of age, growth slows. A maximum and Indian oceans. Jackass morwong are age of 30 years for females and 41 years for distributed in Australian waters from Moreton males was recorded in this Tasmanian study, Bay in Queensland to Perth in WA. They occur in however few fish were older than 25 years. depths to 450 m and, in Australian waters, are most abundant between 100 and 200 m. From the 1950s to the 1970s annual landings of jackass morwong frequently exceeded Jackass morwong have a summer-autumn 1500 t. There was a consistent decline in spawning period with larger, older females landings through the 1980s and 1990s, and by being more fecund. They have an extended 2000 total annual landings were about 800 t, pelagic post-larval stage known as a ‘paperfish’, of which about 50 t were caught off NSW. Most which can be distributed up to 250 km offshore. jackass morwong are caught by trawlers in the After settlement they are demersal fish with Commonwealth South East Fishery, and the juveniles inhabiting the shallow reefs of Bass Commonwealth has developed a quantitative Strait and Tasmania. stock assessment, which considers stocks east Sampling of jackass morwong along the and west of Bass Strait separately. In 2008 southern and eastern shelf region of Tasmania the eastern stock biomass was assessed as showed that newly settled juveniles were about being at about 19% of the unexploited level, STATUS OF FISHERIES RESOURCES IN NSW, 2008/09 JacKASS MORWONG | P 181 WILD FISHERIES RESEARCH PROGRAM and the stock was considered to be subject to Landings by Commercial Fishery of Jackass overfishing (Wilson et al. 2009). However, there Morwong was some uncertainty about the veracity of a separate western stock (which was assessed as Ocean Trap and Line (Key Secondary Species) being at 68% of the unfished biomass) and there Fish Trawl were also concerns about the completeness and accuracy of some of the recent data (e.g. 50 discard rates had been very poorly estimated). The 2009 assessment addressed some of 40 these uncertainties, and the eastern stock was assessed to have improved slightly, to 24% of 30 unfished biomass. The stock of jackass morwong Landings (t) off eastern Australia is still considered to be very 20 significantly depleted. 10 0 97/98 99/00 01/02 03/04 05/06 07/08 Additional Notes Financial Year Reported landings of jackass morwong by NSW • Small quantities are caught by trap fishers in commercial fisheries from 1997/98. Fisheries which southern NSW waters. contribute less than 2.5% of the landings are excluded for clarity and privacy. • Recent buyouts may reduce catch from Commonwealth operators as 8% of the jackass morwong quota was bought back. • There is a minimum legal length of 30 cm Growth Curve of Jackass Morwong total length and a recreational bag limit of 10 for jackass morwong in NSW. 30 Catch 20 Recreational Catch of Jackass Morwong The annual recreational harvest of jackass FL (cm) morwong in NSW is likely to be less than 10 t. 10 This estimate is based upon the results of the offsite National Recreational and Indigenous 0 Fishing Survey (Henry and Lyle, 2003) and onsite surveys undertaken by I & I NSW. 0 5 10 15 20 Age (years) Historical Landings of Jackass Morwong Growth curve of jackass morwong using parameters from Jordan (2001). Lengths are presented as fork length (FL). 1200 1000 800 600 Landings (t) 400 200 0 78/79 83/84 88/89 93/94 98/99 03/04 08/09 Financial Year Commercial landings (including available historical records) of jackass morwong for NSW from 1978/79 to 2008/09 for all fishing methods. Note that the small decline in reported catch during the 1990s was due to changes in catch recording requirements for fishers with both NSW and Commonwealth licences. P 182 | JacKASS MORWONG STATUS OF FISHERIES RESOURCES IN NSW, 2008/09 Length Frequency of Jackass Morwong Further Reading Andrew, N.L., K.J. Graham, K.E. Hodgson and G.N. Gordon (1997). Changes after twenty years 1970/71-1978/79 n = 37 478 in relative abundance and size composition 0.10 of commercial fishes caught during fishery independent surveys on SEF trawl grounds, FRDC Project 96/139. NSW Fisheries Final Report Series. Cronulla, Sydney, NSW Fisheries: 212 pp. 0.06 Proportion Bruce, B.D., K. Evans, C.A. Sutton, J.W. Young and D.M. Furlani (2001). Influence of mesoscale oceanographic processes on larval distribution and 0.02 stock structure in jackass morwong (Nemadactylus macropterus : Cheilodactylidae). ICES Journal of 0.0 Marine Science 58 (5): 1072-1080. 20 30 40 50 Han, V.C.F. (1964). Studies on the biology of the jackass fish,Nemadactylus macropterus Bloch and Schneider 1979/80-1988/89 n = 48 798 (1801). Sydney, University of Sydney. M.Sc. Thesis. 0.10 Henry, G.W. and J.M. Lyle (2003). The National Recreational and Indigenous Fishing Survey. Final Report to the Fisheries Research & Development 0.06 Corporation and the Fisheries Action Program Proportion Project FRDC 1999/158. NSW Fisheries Final Report Series No. 48. 188 pp. Cronulla, NSW Fisheries. 0.02 Jordan, A.R. (1999). The ecology of sand flathead and jackass morwong, University of Tasmania. PhD 0.0 Thesis: 191 pp. 20 30 40 50 Jordan, A.R. (2001). Age, growth and spatial and interannual trends in age composition of jackass 1989/90-1991/92 morwong, Nemadactylus macropterus, in Tasmania. n = 5907 Marine and Freshwater Research 52: 651-660. 0.10 Jordan, A.R. (2001). Spatial and temporal variations in abundance and distribution of juvenile and adult jackass morwong, Nemadactylus macropterus, in 0.06 Proportion south-eastern Tasmania. Marine and Freshwater Research 52: 661-670. Klaer, N.L. (2004). Abundance indices for main 0.02 commercial fish species caught by trawl from the south-eastern Australian continental shelf from 0.0 1918 to 1957. Marine and Freshwater Research 55 (6): 20 30 40 50 561-571. FL (cm) Smith, D.C. (1983). Annual mortality and population The length distribution of jackass morwong landed structure of jackass morwong (Nemadactylus by NSW commercial fishers between 1970 and 1992 macropterus Bloch & Schneider) in eastern remained reasonably stable and comprised mainly fish Australian waters. Australian Journal of Marine and between 25 and 40 cm fork length (FL). No recent length Freshwater Research 34: 253-260. composition data are available for NSW catches. The minimum legal length for jackass morwong in NSW is Wilson, D., R. Curtotti, G. Begg and K. Phillips, Eds. 30 cm total length. (2009). Fishery Status Reports 2008: status of fish stocks and fisheries managed by the Australian Government. Canberra, Bureau of Rural Sciences & Australian Bureau of Agricultural and Resource Economics. Please visit the CSIRO website, http://www.marine.csiro.au/caab/ and search for the species code (CAAB) 37 377003, 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. JacKASS MORWONG | P 183 WILD FISHERIES RESEARCH PROGRAM P 184 | JacKASS MORWONG.