Ibacus peronii, Ibacus brucei, Ibacus chacei, Ibacus alticrenatus, Ibacus spp.

  • John Stewart (Department of Primary Industries, New South Wales)
  • Brad Zeller (Department of Agriculture and Fisheries, Queensland)
  • Craig Noell (South Australian Research and Development Institute)
  • Brett Ingram (Victorian Fisheries Authority)
  • Mervi Kangas (Department of Primary Industries and Regional Development, Western Australia)

You are currently viewing a report filtered by jurisdiction. View the full report.

Toggle content


Australia has four closely related species of fan lobster. These are collectively assessed as Balmain Bugs. The main east coast stock in NSW and QLD is sustainable. Stocks in WA and SA are considered negligible. Stocks are undefined in VIC.

Toggle content

Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Queensland East Coast ECOTF Sustainable Catch rates, catch, effort, size structure, risk assessment
East Coast Otter Trawl Fishery (QLD)
Toggle content

Stock Structure

The common name ‘Balmain Bug’ refers to four similar species of fan lobster: Ibacus alticrenatus, I. brucei, I. chacei and I. peronii [Haddy et al. 2007]. These species partially overlap in their distributions on the east coast of Australia and have evolved different life-history strategies, tending to occupy different depth ranges. However, here, they are assessed as a single species group because they are rarely distinguished by fishers or fish marketers.

The true Balmain Bug (I. peronii) is widely distributed around the southern half of the continent, from around the Queensland–New South Wales border (latitude 28°S) to central Western Australia (latitude 29°S), including the east coast of Tasmania and Bass Strait. The true Balmain Bug is mainly found close to shore, in waters less than 80 m deep. The Smooth Bug (I. chacei) is distributed between northern Queensland (latitude 17°S) and southern New South Wales (latitude 36°S), although it is rarely caught south of Sydney (latitude 34°S). It is most abundant on the mid-continental shelf in depths of 50–150 m. The Honey Bug (I. brucei) is distributed between central Queensland and northern New South Wales. It is most abundant on the outer continental shelf and upper slope in waters from 120–300 m deep. The Deepwater Bug (I. alticrenatus) is distributed throughout southern Australian and New Zealand waters. It is most abundant at depths of 200–400 m on the upper continental slope, and stock structure remains unknown [Haddy et al. 2007].

Given the prevailing influence of the East Australian Current along the east coast out to 150 m depth, a protracted pelagic larval phase and a northerly migration of older stages, true Balmain Bugs, Smooth Bugs and Honey Bugs are thought to each constitute single biological stocks across Queensland and New South Wales [Haddy et al. 2007]. Stock status of the Balmain Bugs species group in these jurisdictions is therefore presented at the biological stock level—East Coast biological stock.

Landings in Victoria, South Australia and Western Australia are thought to be predominantly true Balmain Bugs (I. peronii). However, the stock relationship between Balmain Bugs caught in these jurisdictions and those caught off New South Wales and Queensland is unknown. Stock status in these jurisdictions is therefore presented at the jurisdictional level.

Toggle content

Stock Status

East Coast

In Queensland, fishers harvest Balmain Bugs as a byproduct of Eastern King Prawn fishing. Logbook data indicate that Balmain Bugs contribute only a very minor component of the Eastern King Prawn fishers’ catch and landed value. Balmain Bugs fishing mortality is managed by a prohibition on landing of egg-bearing females; conservative minimum legal size (MLS), which were updated in 2009; and mandatory use of turtle excluder devices since the early 2000s, which have been shown to lower the incidental catch rates of scyllarid lobsters, including Balmain Bugs [Courtney et al. 2007, Courtney et al. 2008]. In addition, the spawning stock is partly protected from fishing during an annual seasonal closure. Landings in 2017 were 45 per cent below the 2000–16 average of 76 tonnes (t) per year. Nominal catch rates since 2011 continue to decline and the 2017 catch at 42 t was relatively low. This is considered to be a result of increased MLS for I. chacei and recently changed fishing practices and not declining abundance.

Risk assessment of the Queensland East Coast Otter Trawl Fishery found a low risk of recruitment overfishing the Queensland part of the East Coast Balmain Bug stock south of the Great Barrier Reef Marine Park (GBRMP) at the 2009 fishing effort level [Jacobsen et al. 2018], where about 83 per cent of the catch is taken. The average annual number of days when Eastern King Prawn was harvested in Queensland has increased slightly since 2009 by five per cent, not greatly raising the risk of overfishing the main part of the Queensland stock. The risk of recruitment overfishing within the GBRMP has also been assessed and found to be intermediate to high [Pears et al. 2012]. However, annual fishing effort in the GBRMP has declined by an average of 17 per cent since 2009, substantially reducing risk for this part of the stock.

The above evidence indicates that the biomass of the Queensland part of the stock is unlikely to be depleted, recruitment is unlikely to be impaired, and the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

In New South Wales, Balmain Bugs (primarily I. peronii and I. chacei) are trawl target species and have been assessed in terms of their commercial nominal catch rates and length compositions in landings. Median catch rates (kg per day in the ocean prawn trawl fishery) have fluctuated throughout the past 25 years but have shown no overall trends and the size compositions in landings have remained stable for both species [NSWDPI unpublished]. The above evidence indicates that the biomass of this part of the stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Landings have declined slowly during the past 15 years, from an average of approximately 63 t per year during 2002–03 to 2006–07 to 26 t per year during 2012–13 to 2016–17. Current landings are at historically low levels (18 t in 2016-17) as a result of a large reduction in fishing effort, with the number of ocean prawn trawling days fished in 2016–17 being less than 30 per cent of those fished in 2000 [NSWDPI unpublished]. This reduction in fishing effort in combination with stable size compositions in landings indicates that fishing mortality is constrained in New South Wales waters to sustainable levels. The above evidence indicates that the current level of fishing pressure is unlikely to cause this part of the stock to become recruitment impaired.

On the basis of the evidence provided above, the entire East Coast biological stock is classified as a sustainable stock.

Toggle content


Balmain Bugs biology [Haddy et al. 2005, Haddy et al. 2007, Stewart 1999, Stewart et al. 1997, Stewart and Kennelly 2000]

Species Longevity / Maximum Size Maturity (50 per cent)
BALMAIN BUGS Balmain Bug: 15 years, 86 mm CL Smooth Bug: 5–7 years, 80 mm CL Honey Bug: longevity largely unknown, maximum CL in Queensland samples is 72 mm for females and 66 mm for males. Deepwater Bug: longevity largely unknown, maximum CL in Queensland samples is 55 mm for both females and males. Balmain Bug: 2 years, 50 mm CL Smooth Bug: 2 years, 55 mm CL Honey Bug: 47 mm CL Deepwater Bug: 45 mm CL Balmain Bug: 2 years, 50 mm CL Smooth Bug: 2 years, 55 mm CL Honey Bug: 47 mm CL Deepwater Bug: 45 mm CL
Toggle content


Distribution of reported commercial catch of BALMAIN BUGS
Toggle content


Fishing methods
Otter Trawl
Management methods
Method Queensland
Limited entry
Retention of females with eggs prohibited
Size limit
Vessel restrictions
Commercial 42.16t in ECOTF
East Coast Otter Trawl Fishery (QLD)

Queensland – Indigenous (management methods) In Queensland, under the Fisheries Act 1994, Indigenous fishers can 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.

New South Wales – Indigenous (management methods) (a) Bag limits - The 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 themselves; (b) Section 37 (1d)(3)(9), Aboriginal cultural fishing authority - The Aboriginal cultural fishing authority is the authority that Indigenous persons can apply to take catches outside the recreational limits under the Fisheries Management Act 1994 (NSW), Section 37 (1d)(3)(9), Aboriginal cultural fishing authority; and (c) Native Title - In cases where the Native Title Act 1993 (Cth) applies fishing activity can be undertaken by the person holding native title in line with S.211 of that Act, which provides for fishing activities for the purpose of satisfying their personal, domestic or non-commercial communal needs. In managing the resource where native title has been formally recognised, the native title holders are engaged with to ensure their native title rights are respected and inform management of the State's fisheries resources.

Victoria – Indigenous (management methods) In Victoria, regulations for managing recreational fishing may not apply to fishing activities by Indigenous people. Victorian traditional owners may have rights under the Commonwealth's Native Title Act 1993 to hunt, fish, gather and conduct other cultural activities for their personal, domestic or non-commercial communal needs without the need to obtain a licence. Traditional Owners that have agreements under the Traditional Owner Settlement Act 2010 (Vic) may also be authorised to fish without the requirement to hold a recreational fishing licence. Outside of these arrangements, Indigenous Victorians can apply for permits under the Fisheries Act 1995 (Vic) that authorise fishing for specific Indigenous cultural ceremonies or events (for example, different catch and size limits or equipment). There were no Indigenous permits granted in 2017 and hence no Indigenous catch recorded.

Toggle content

Catch Chart

Commercial catch of BALMAIN BUGS - note confidential catch not shown
Toggle content


  1. Courtney, AJ, Campbell, MJ, Roy, DP, Tonks, ML, Chilcott, KE and Kyne, PM 2008, Round scallops and square-meshes: a comparison of four codend types on the catch rates of target species and bycatch in the Queensland (Australia) Saucer Scallop (Amusium balloti) trawl fishery, Marine and Freshwater Research, (59): 849–864.
  2. Courtney, AJ, Haddy, JA, Campbell, MJ, Roy, DP, Tonks, ML, Gaddes, SW, Chilcott, KE, O’Neill, MF, Brown, IW, McLennan, M, Jebreen, JE, Van Der Geest, C, Rose, C, Kistle, S, Turnbull, CT, Kyne, PM, Bennett,MB and Taylor, J 2007, Bycatch weight, composition and preliminary estimates of the impact of bycatch reduction devices in Queensland’s trawl fishery, Department of Primary Industries and Fisheries. Project No. 2000/170 Report to the Fisheries Research and Development Corporation, May 2007.
  3. Haddy, JA, Courtney, AJ and Roy, DP 2005, Aspects of the reproductive biology and growth of Balmain Bugs (Ibacus spp.) (Scyllaridae), Journal of Crustacean Biology, 25(2): 263–273.
  4. Haddy, JA, Stewart, J and Graham, KJ 2007, Fishery and biology of commercially exploited Australian fan lobsters (Ibacus spp.), in KL Lavalli and E Spanier (eds), The biology and fisheries of the Slipper Lobster, Crustacean Issues, vol. 17, CRC Press, Boca Raton.
  5. Jacobsen, I, Zeller, B, Dunning, M, Garland, A, Courtney T and Jebreen, E 2018, An Ecological Risk Assessment of the Southern Queensland East Coast Otter Trawl Fishery and River and Inshore Beam Trawl Fishery, Fisheries Queensland, Department of Agriculture and Fisheries, Brisbane.
  6. NSWDPI Unpublished. Status of Australian Fish Stocks 2018 – NSW Stock status summary – Balmain Bugs (Ibacus peronii, Ibacus brucei, Ibacus chacei, Ibacus alticrenatus).
  7. Pears, RJ, Morison, AK, Jebreen, EJ, Dunning, M, Pitcher, CR, Courtney, AJ, Houlden, B and Jacobsen, IP 2012, Ecological Risk Assessment of the East Coast Otter Trawl Fishery in the Great Barrier Reef Marine Park: Summary Report, Great Barrier Reef Marine Park Authority, Townsville.
  8. Stewart, J 1999, Aspects of the biology of Balmain and Smooth Bugs, Ibacus spp. (Decapoda: Scyllaridae) off Eastern Australia, PhD thesis, University of Sydney.
  9. Stewart, J and Kennelly, SJ 2000, Growth of the scyllarid lobsters Ibacus peronii and I. chacei, Marine Biology, 136: 921–930.
  10. 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: 391pp.
  11. Stewart, J, Kennelly, SJ and Hoegh-Guldberg, O 1997, Size at sexual maturity and the reproductive biology of two species of scyllarid lobster from New South Wales and Victoria, Australia, Crustaceana, 70(3): 344–367.
  12. VFA Unpublished. Species Stock Status Summary 2017 - Balmain Bugs

Downloadable reports

Click the links below to view reports from other years for this fish.