I & I NSW Wild Fisheries research Program Bugs ( spp.)

Exploitation Status Fully Fished

Four of bugs are marketed in NSW; but two species dominate commercial landings and both these species are considered to be fully fished. The recreational catch is insignificant.

Scientific name common name comment

Inshore species found mainly off central Ibacus chacei smooth bug and northern NSW.

Inshore species found mainly off southern eastern Balmain bug and central NSW.

Ibacus peronii Image © Bernard Yau

Background Trawlers off NSW catch four of the eight known A less commonly caught species is the smaller species of Ibacus, collectively marketed as (< 7.5 cm CL) Bruce’s bug (I. brucei) that mainly ‘Balmain bugs’. The most commonly caught NSW inhabits outer continental shelf and upper species are the ‘true’ eastern Balmain bug (Ibacus slope depths (120-300 m) off northern NSW and peronii) and the smooth bug (I. chacei) which . A second small species both grow in size to 8-9 cm carapace length (CL) (< 6.5 cm CL) is the deepwater bug and weigh between 300 and 400 g. The eastern (I. alticrenatus) which occurs mainly at depths Balmain bug occurs mainly on inshore grounds of 200 to 400 m around southern ; it is (<80 m deep) and is distributed around southern also found in New Zealand waters. Bruce’s bug Australia from about the NSW-Queensland is occasionally targeted by trawlers off border to southern WA including the east coast the NSW north coast and small quantities of of and Bass Strait. The smooth bug is deepwater bugs are caught by trawlers targeting mostly caught on deeper grounds (40 to fish or on the upper continental slope. 120 m) and is found off eastern Australia north More than 85% of the Australian Balmain bug from about Sydney to central Queensland. catch of about 200 t annually is harvested from northern NSW and southern Queensland waters,

status of fisheries resources in nsw, 20008/09 Bugs | p 61 wild fisheries research program

mostly as a by-product of prawn ; about Additional Notes 80% of this catch consists of smooth bugs. Balmain bugs are also taken as an incidental • Bugs are taken incidentally by prawn and fish catch by other trawl fisheries off southern NSW trawling in ocean waters off NSW. and in other states, and small quantities of • The two main species, smooth bug, Ibacus bugs are caught incidentally in spanner chacei, and eastern Balmain bug, I. peronii, are traps. There is no recreational fishery for bugs inshore species found mainly in depths less in NSW. It should be noted that an annual than 100m, whereas I. brucei and I. alticrenatus catch of around 400 t of Moreton Bay bugs or are found on the outer shelf and upper slope Bay ( spp.) are also landed by (150-400 m). Queensland trawlers. • Smooth and Balmain bugs have overlapping Research into NSW bugs revealed distinct distributions; however smooth bugs are a differences in life histories between the eastern more northern species and are abundant in Balmain and smooth bugs. Eastern Balmain bugs Queensland waters. may live for more than 15 years whereas smooth • Landings of these species continue to be bugs have a maximum life span of about 7 years. monitored with length-based sampling. Tagged smooth bugs showed a northward movement pattern that was not evident for • There is a minimum legal length of 10 cm tagged eastern Balmain bugs. Studies of their carapace width and a recreational bag limit of reproductive biology showed that maturing 20 bugs. smooth bugs moved northwards to spawn in waters off Queensland, whereas eastern Balmain bugs spawned throughout their range along Catch the NSW coast. It appears that smooth bug Recreational Catch of Bugs larvae (phyllosomata) disperse south on the East Australian Current and settle as juveniles on the The annual recreational harvest of bugs in NSW NSW continental shelf. is likely to be less than one tonne. Size at maturity for eastern Balmain and smooth bugs is around 5 cm CL. In 1999, a minimum legal size of 10 cm (carapace width) was introduced for eastern Balmain and smooth bugs Historical Landings of Bugs based on their average size of female maturity. Little is known of the biology of the other 120 species although the peak egg-bearing period 100 for all NSW bugs is winter. The two large species of bugs (I. chacei and 80

I. peronii) are not differentiated in catch returns 60 but sampling will be used to assess the catch Landings (t) composition. Collectively, bugs are considered 40 to be fully fished in NSW waters although no detailed stock assessments have been 20 completed. In Queensland, the fact that bugs 0 are relatively long-lived , with low 68/69 73/74 78/79 83/84 88/89 93/94 98/99 03/04 08/09 fecundity and relatively low population densities Financial Year has led to concern that they may be vulnerable to overexploitation. Commercial landings (including available historical records) of bugs for NSW from 1969/70 to 2008/09 for all fishing methods. Records from the mid to late 1980s are incomplete.

p 62 | Bugs status of fisheries resources in nsw, 2008/09

Length Frequency of Eastern Balmain Bugs Length Frequency of Smooth Bugs 0.15

1992/93−1994/95 0.35 2000/01−2006/07 n = 1798 n = 19 831 0.30 0.25 0.10 0.20 Proportion 0.15 Proportion 0.05 0.10 0.05 0.00 0.00 4 5 6 7 8 9 10 4 5 6 7 8 9 10 0.15

2000/01−2006/07 0.35 2007/08−2008/09 n = 5150 n = 9889 0.30 0.25 0.10 0.20 Proportion 0.15 Proportion 0.05 0.10 0.05 0.00 0.00 4 5 6 7 8 9 10 4 5 6 7 8 9 10 CL (cm)

0.15 2007/08−2008/09 The length distribution of smooth bugs in NSW n = 1277 commercial catches included a high proportion of bugs less than 5 cm CL prior to the introduction in 1999 of the minimum legal length of 10 cm carapace width 0.10 (approximately 5 cm CL). In recent years the length distribution of smooth bugs landed by NSW commercial fishers has mainly comprised bugs between 5 and 7 cm Proportion

0.05 CL. 0.00

4 5 6 7 8 9 10 CL (cm) The length distribution of eastern Balmain bugs in NSW commercial landings has remained relatively stable since the 1990s, and is mainly comprised of bugs between 5 and 9 cm carapace length (CL). The introduction in June 1999 of a minimum legal length of 10 cm carapace width (approximately 5 cm CL) has apparently had little impact of the size composition of landings of eastern Balmain bugs. Growth Curves ofEastern Eastern Balmain Balmain Bug (Ibacus Bugsperonii) Growth Curves of SmoothSmooth Bug Bugs (Ibacus chacei) 8 female female male male 6 6 4 4 CL (cm) CL (cm) 2 2 0 0

2 4 6 8 10 2 4 6 8 10

Age (years) Age (years) Growth curves of eastern Balmain bug using parameters Growth curves of smooth bug using parameters from from Stewart and Kennelly (2000). Lengths are presented Stewart and Kennelly (2000). Lengths are presented as as carapace length (CL). carapace length (CL). Bugs | p 63 wild fisheries research program

Landings by Commercial Fishery of Bugs Haddy, J.A., J. Stewart and K.J. Graham (2007). Fishery and biology of commercially exploited Australian Ocean Prawn Trawl (Primary Species) fan lobsters (Ibacus spp.). The Biology and Fisheries Fish Trawl (Primary Species) of the Slipper . K. L. Lavalli and E. Spanier. Boca Raton, Florida, CRC Press. 17: 359-375. 80 Jones, D.S. and G.J. Morgan (1994). A Field Guide to Crustaceans of Australian Waters. Sydney, Reed

60 Publications. Queensland Fisheries. (2010). Stock status of 40

Landings (t) Queensland’s fisheries resources 2009-10. Queensland, Department of Employment, Economic

20 Development and Innovation: 65 pp. Stewart, J. (1999). Aspects of the biology of Balmain 0 and smooth bugs Ibacus spp. ( : 97/98 99/00 01/02 03/04 05/06 07/08 Scyllaridae) off eastern Australia, University of Financial Year Sydney. PhD Thesis. Comercial landings of bugs by NSW commercial fisheries from 1997/98. Fisheries which contribute less than 2.5% Stewart, J. (2003). Long-term recaptures of tagged of the landings are excluded for clarity and privacy. Scyllarid lobsters (Ibacus peronii) from the east coast of Australia, Fisheries Research 63: 261-264. Stewart, J. and S.J. Kennelly (1997). Fecundity and Catch Per Unit Effort Information of Bugs Harvested egg-size of the Balmain Bug Ibacus peronii (Leach, 1815) (Decapoda, Scyllaridae) off the east coast of by Ocean Prawn Trawling in NSW Australia. Crustaceana 70: 191-197.

1.0 Stewart, J. and S.J. Kennelly (1998). Contrasting movements of two exploited Scyllarid lobsters of the Ibacus off the east coast of Australia. 0.8 Fisheries Research 36 (2-3): 127-132.

0.6 Stewart, J. and S.J. Kennelly (2000). Growth of the scyllarid lobsters Ibacus peronii and I. chacei. Marine Biology 136 (5): 921-930. 0.4

Relative Catch Rate Stewart, J., S.J. Kennelly and O. Hoegh-guldberg (1995). An optimal strategy for sampling oocytes 0.2 in female balmain bugs Ibacus peronii Leach (Decapoda, Scyllaridae). Invertebrate Reproduction & 0.0 Development 28 (1): 7-11. 93/94 98/99 03/04 08/09 Financial Year Stewart, J., S.J. Kennelly and O. Hoegh-Guldberg (1997). Size at sexual maturity and the reproductive Catch rates of bugs harvested using Ocean Prawn Trawling for NSW. Two indicators are provided: (1) biology of two species of scyllarid lobster from New median catch rate (lower solid line); and (2) 90th South Wales and Victoria, Australia. Crustaceana 70: percentile of the catch rate (upper dashed line). Note that 344-367. catch rates are not a robust indicator of abundance in many cases. Caution should be applied when interpreting these results. Please visit the CSIRO website, http://www.marine.csiro.au/caab/ and search for the species code (CAAB) 28 821019, 28 821004, 28 Further Reading 821001 and 28 821010, common name or scientific Brown, D.E. and L.B. Holthuis (1998). The Australian name to find further information. species of the genus Ibacus (Crustacea: Decapoda: Scyllaridae), with the description of a new species and addition of new records. Zoologische Mededelingen (Leiden) 72: 113-141. Haddy, J.A., A.J. Courtney and D.P. Roy (2005). Aspects of the reproductive biology and growth of Balmain bugs (Ibacus spp.) (Scyllaridae). Journal of Biology 25: 263-273.

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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 p 64 | Bugs user’s independent adviser.