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

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

Date Published: June 2021

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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.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Stock status Indicators
New South Wales East Coast Sustainable

Catch rates, catch, effort, size structure, risk assessment

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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.

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Stock Status

East Coast

In Queensland, Balmain Bugs form a very minor by-product harvest in the trawl fishery for Eastern King Prawn. Balmain Bugs fishing mortality is managed by a prohibition on landing of egg-bearing females; a conservative minimum legal size (MLS), which was updated in 2009; and mandatory use of turtle excluder devices since the early 2000s, which also 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 2019 were 37 per cent below the 2000–18 average of 75 tonnes (t) per year. Nominal catch rates declined from 2011 to 2016 however they have been relatively steady since [QFISH 2020]. The 2019 catch at 47 t was slightly greater than the previous two years but still low compared to the long-term average harvest. The lower harvest from 2017 to 2019 is considered to be a result of increased MLS for I. chacei and changed fishing practices rather than declining abundance.

An ecological 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 post 2009 for the Eastern King Prawn fishery is similar to 2009, indicating that the risk of overfishing the main part of the Queensland Balmain Bug stock is unchanged. 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 of overfishing for this part of the stock.

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 and show an overall slight increase, especially during 2018-19 when the catch rate was approximately double the average catch rate during the previous five years [Stewart 2020]. 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 fluctuate annually but show an overall decline during the past 15 years, from an average of approximately 63 t per year during 2002–03 to 2006–07 to 36 t per year during 2014–15 to 2018–19. Landings in recent years have been increasing with approximately 58 t being reported during 2018-19 which is the highest catch since 2004-05.  Nevertheless, effort in the ocean prawn fishery has declined substantially since the early 2000s, from approximately 16,000 days to an average of 4,660 days during the previous 5 years [Stewart 2020]. This reduction in fishing effort in combination with stable size compositions in landings [Stewart 2020] 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.

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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
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Distribution of reported commercial catch of BALMAIN BUGS

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Fishing methods
New South Wales
Otter Trawl
Management methods
Method New South Wales
Limited entry
Size limit
Spatial closures
Vessel restrictions
Customary fishing management arrangements
Bag limits
Marine park closures
Possession limit
Size limit
Spatial closures
New South Wales
Commercial 51.91t
Indigenous Unknown
Recreational Unknown

Queensland – Indigenous (management methods) for more information see https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

New South Wales – Indigenous (management methods) https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing

Victoria – Indigenous (Management Methods) A person who identifies as Aboriginal or Torres Strait Islander is exempt from the need to obtain a Victorian recreational fishing licence, provided they comply with all other rules that apply to recreational fishers, including rules on equipment, catch limits, size limits and restricted areas. Traditional (non-commercial) fishing activities that are carried out by members of a traditional owner group entity under an agreement pursuant to Victoria’s Traditional Owner Settlement Act 2010 are also exempt from the need to hold a recreational fishing licence, subject to any conditions outlined in the agreement. Native title holders are also exempt from the need to obtain a recreational fishing licence under the provisions of the Commonwealth’s Native Title Act 1993.

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Catch Chart

Commercial catch of BALMAIN BUGS 

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  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. 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.
  7. QFish, Department of Agriculture and Fisheries, www.qfish.gov.au
  8. Stewart J 2020, Status of Australian Fish Stocks 2020 – NSW Stock status summary – Balmain Bugs (Ibacus peronii, Ibacus brucei, Ibacus chacei, Ibacus alticrenatus).
  9. Stewart, J 1999, Aspects of the biology of Balmain and Smooth Bugs, Ibacus spp. (Decapoda: Scyllaridae) off Eastern Australia, PhD thesis, University of Sydney.
  10. Stewart, J and Kennelly, SJ 2000, Growth of the scyllarid lobsters Ibacus peronii and I. chacei, Marine Biology, 136: 921–930.
  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.

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