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Stock Status Overview
|Queensland||Eastern Australia||ECIFFF||Sustainable||Catch, CPUE, length and age frequencies|
- East Coast Inshore Fin Fish Fishery (QLD)
Extensive tagging studies1 suggest a single east coast biological stock of Sea Mullet, extending from central Queensland to eastern Victoria. The biological stock structure of Sea Mullet off Western Australia is likely to be complex, although limited tagging and genetic studies2,3 suggest mixing of fish throughout the lower west coast region, where the majority of the catch is taken. Therefore, a single Western Australian biological stock is assumed.
Here, assessment of stock status is presented at the biological stock level—Western Australia and Eastern Australia.
This cross-jurisdictional biological stock has components in Queensland and New South Wales. Each jurisdiction assesses the part of the biological stock that occurs in its waters. The status presented here for the entire biological stock has been established using evidence from both jurisdictions.
The Queensland component of the Eastern Australian biological stock has a long history of stable commercial landings. In 2015, 1982 t was reported landed, which is close to the long-term average of around 2000 t. Length frequency information from routine monitoring shows stable distributions of fish sizes harvested by the Queensland fishery5. Age frequency information shows fish from three to five years old dominate catches, but older fish are present. Recruitment has been consistent, with evidence of recent strong year classes. The above evidence indicates that the biomass of the Queensland component of this stock is unlikely to be recruitment overfished.
Nominal effort in the Queensland component of the fishery has reduced from 8850 days in 2013 to 7505 in 2015, and the number of fishers reporting mullet (unspecified) catch has reduced from 287 fishers to 248 fishers over the same period. This decline is attributed to recent Queensland government funded buybacks of net fishing licences. Length frequency information shows stable patterns, and catch is well above minimum legal size. Age frequency information shows continued recruitment to the fishery and evidence of strong year classes. Estimates of fishing mortality are high compared with estimates of natural mortality, but they show a stable trend in combination with consistent catches. The above evidence indicates that the current level of fishing pressure is unlikely to cause the Queensland component of the stock to become recruitment overfished.
The New South Wales component of the Eastern Australian biological stock is assessed annually in terms of landings and catch rates (CPUE) in both the estuary and ocean fisheries6. The annual spawning run fishery on ocean beaches is also assessed in terms of fish sizes and ages in landings. Commercial median catch rates have remained stable in the estuary fishery (kg per day of mesh netting) and increased slightly in the ocean fishery (kg per day of beach hauling) since the early 1980s. The size compositions of fish in ocean landings have remained stable, while the age compositions of fish in this fishery are generally between two and five years old, with some variations in year class strength. The above evidence indicates that the biomass of the New South Wales component of the stock is unlikely to be recruitment overfished.
Landings in New South Wales in 2015 (2328 t) were below the long-term annual average (around 3000 t). The reported number of fisher days in the ocean fishery in 2015 was at a historical low of approximately 350, down from around 900 days in 2010. Typical length and age frequency compositions were found in landings in 2015, with most fish being between three and seven years of age, suggesting no large changes in the stock. The above evidence indicates that the current level of fishing pressure is unlikely to cause the New South Wales component of the stock to become recruitment overfished.
On the basis of the evidence provided above, the Eastern Australian biological stock is classified as a sustainable stock.
Sea Mullet biology5,7,8,9
|Species||Longevity / Maximum Size||Maturity (50 per cent)|
|Sea Mullet||Eastern Australia: 16 years; 640 mm FL Western Australia: 12 years; 790 mm FL||Eastern Australia: Males 300 mm TL; Females 330 mm TL Western Australia: Males and Females 370 mm TL|
Distribution of reported commercial catch of Sea Mullet
|249 in ECIFFF|
- East Coast Inshore Fin Fish Fishery (QLD)
|Commercial||1.99Kt in ECIFFF|
- East Coast Inshore Fin Fish Fishery (QLD)
a Queensland – Indigenous (management methods) In Queensland, under the Fisheries Act 1994, Indigenous fishers are able 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 can be obtained through permits.
b New South Wales – Indigenous (management methods) Aboriginal Cultural Fishing Interim Access Arrangement—allows an Indigenous fisher in New South Wales to take in excess of a recreational bag limit in certain circumstances, for example, if they are doing so to provide fish to other community members who cannot harvest for themselves.
c New South Wales – Indigenous (management methods) Aboriginal Cultural Fishing authority—the authority to which Indigenous persons can apply to take catches outside the recreational limits under the NSW Fisheries Management Act 1994 (NSW), Section 37 (1)(c1), Aboriginal cultural fishing authority.
Commercial catch of Sea Mullet - note confidential catch not shown
Effects of fishing on the marine environment
- The main fisheries for Sea Mullet use beach seining. This fishing method is highly targeted and as a result there is very little bycatch in these fisheries10. In Queensland, the component of by-product caught in estuarine gillnets in the Sea Mullet fishery is less than 20 per cent by number, and much of this is retained and marketed11.
Environmental effects on Sea Mullet
- Sea Mullet penetrate far up rivers, often into fresh water, and barriers to fish passage (such as weirs and dams) can reduce the amount of habitat available to the species. Being highly dependent on riverine and estuarine habitats12, Sea Mullet populations are vulnerable to fluctuations in water quality. Eutrophication and hypoxia can cause significant fish kills.
Kesteven, GL 1953, Further results of tagging sea mullet, Mugil cephalus Linnaeus, on the eastern Australian coast, Australian Journal of Marine and Freshwater Research, 4: 251–306.
Thomson, JM 1951, Growth and habits of the sea mullet, Mugil dobula Gunther, in Western Australia, Australian Journal of Marine and Freshwater Research, 2: 193–225.
Watts, RJ and Johnson, MS 2004, Estuaries, lagoons and enclosed embayments: habitats that enhance subdivision of inshore fishes, Marine and Freshwater Research, 55: 641–651.
Fletcher, WJ and Santoro, K (eds) 2015, Status reports of the fisheries and aquatic resources of Western Australia 2014/15: the state of the fisheries. Western Australian Department of Fisheries, Perth.
Fisheries Queensland monitoring data 1999–2015, Monitoring our fisheries, Queensland Department of Agriculture and Fisheries.
Stewart, J, Hegarty, A, Young, C, Fowler, AM and Craig, J 2015, Status of fisheries resources in NSW 2013–14, NSW Department of Primary Industries, Mosman, 391 pp.
Virgona, JL, Deguara, KL, Sullings, DJ, Halliday, I and Kelly, K 1998, Assessment of the stocks of sea mullet in New South Wales and Queensland Waters. Final Report Series No. 2. New South Wales Fisheries, Cronulla.
Gaughan, D, Ayvazian, S, Nowara, G and Craine, M 2006, The development of a rigorous sampling methodology for a long-term annual index of recruitment for finfish species from south-western Australia, Final report, Fisheries Research and Development Corporation project 1999/153, Fisheries Research Report 154, Western Australian Department of Fisheries, Perth.
Smith, KA and Deguara, KL 2002, Review of biological information and stock assessment for the NSW sea mullet resource, NSW Fisheries Resource Assessment Series No. 12, New South Wales Fisheries, Cronulla.
Broadhurst, MK, Wooden, MEL and Miller, RB 2007, Isolating selection mechanisms in beach seines, Fisheries Research, 88: 56–69.
- 11 Halliday, IA, Ley, JA, Tobin, A, Garrett, R, Gribble, NA and Mayer, DG 2001, The effects of net fishing: addressing biodiversity and bycatch issues in Queensland inshore waters, Fisheries Research and Development Corporation project 136 97/206), Department of Primary Industries, Queensland.
Fowler, AM., Smith, SM, Booth, DJ and Stewart, J 2016, Partial migration of grey mullet (Mugil cephalus) on Australia’s east coast revealed by otolith chemistry. Marine Environmental Research, 119: 238–244.