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Western Rock Lobster

Panulirus cygnus

  • Simon de Lestang (Department of Fisheries, Western Australia)
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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Western Australia West Coast Rock Lobster Managed Fishery WCRLMF Sustainable Catches, catch rate, recruitment, egg production and harvest rate
WCRLMF
West Coast Rock Lobster Managed Fishery (WA)
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Stock Structure

Western Rock Lobster is a single biological stock, with a distribution along the mid–lower west coast of Western Australia1,2.

Here, assessment of stock status is presented at the biological stock level—West Coast Rock Lobster Managed Fishery (Western Australia).

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Stock Status

West Coast Rock Lobster Managed Fishery

The stock status for Western Rock Lobster (Panulirus cygnus) is determined using a weight of evidence approach based on empirical and modelled estimates of a range of indices, including catches, catch rates, recruitment, egg production and harvest rate3.

The most recent assessment shows that catches in the West Coast Rock Lobster Managed Fishery (Western Australia) have increased slightly over the past few seasons due to small increases in quota and an increase in recreational catch however, they remain 55 per cent lower than the historical average level of catch. Standardised commercial catch rates indicate that biomass has increased in recent years and is now over three-times greater than under input controls. Under current exploitation rates, catch rates are predicted to remain stable or increase. The Integrated Population Model (IPM) indicates that catch rates in all locations of the fishery will continue to increase with a continuation of fishing at similar or slightly higher total allowable commercial catches (TACCs) than in the recent past.

Puerulus (post-larval lobsters) monitoring indicates that the current settlement levels are slightly below the historic average. The IPM suggests that this is sufficient to maintain/increase stock abundance at current harvest levels. The IPM currently indicates that the fishery is operating at harvest rates of between 25–30 per cent and these will continue to decline at current or slightly higher TACCs. Fishery-independent egg production indices at all sites are well above long-term levels and above threshold reference levels. These indices indicate high levels of spawning stock exist throughout the fishery. The IPM indicates that the biomass and egg production in all locations of the fishery is currently at the highest levels recorded since the mid-1970s, and that a continuation of fishing at similar or slightly higher TACCs will continue to result in increasing biomass and catch rates.

The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished, and the current level of fishing pressure is unlikely to cause the stock to become recruitment overfished.

On the basis of the evidence provided above, the West Coast Rock Lobster Managed Fishery (Western Australia) biological stock is classified as a sustainable stock.

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Biology

Western Rock Lobster biology3

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Western Rock Lobster 20+ years; >150 mm  CL  5–7years; 65–80 mm  CL, depending on location
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Distributions

Distribution of reported commercial catch of Western Rock Lobster

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Tables

Fishing methods
Western Australia
Commercial
Batten and beehive pots
Indigenous
Diving
Rock Lobster And Crayfish Traps And Pots
Recreational
Diving
Rock Lobster And Crayfish Traps And Pots
Management methods
Method Western Australia
Commercial
Gear restrictions
Limited entry
Size limit
Spatial closures
Total allowable catch
Indigenous
Bag limits
Gear restrictions
Size limit
Recreational
Bag limits
Gear restrictions
Size limit
Spatial closures
Temporal closures
Active vessels
Western Australia
237 in WCRLMF
WCRLMF
West Coast Rock Lobster Managed Fishery (WA)
Catch
Western Australia
Commercial 6.05Kt in WCRLMF
Indigenous Unknown
Recreational 330t
WCRLMF
West Coast Rock Lobster Managed Fishery (WA)

a Indigenous Subject to the defence that applies under section 211 of the Native Title Act 1993 (Cth), and the exemption from a requirement to hold a recreational fishing licence, the non-commercial take by indigenous fishers is covered by the same arrangements as that for recreational fishing.
b Western Australia – Commercial (catch) The commercial fishing season spans 15 January 2015–14 January 2016.c Western Australia – Indigenous (catch) The recreational fishing season spans 15 October 2014–30 June 2015.

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Catch Chart

Commercial catch of Western Rock Lobster

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Effects of fishing on the marine environment

  • The legislated design of rock lobster pots (batten and beehive), including the materials they are made from, prevents ‘ghost fishing’ problems. A study of human impacts on the marine environments of the Abrolhos Islands estimated that potting impacts less than 0.3 per cent of the surface area of fragile habitat (corals)4. For the coastal fishery, rock lobster fishing occurs on sand areas around robust limestone reef habitats, covered with coralline algae and macro-algae such as kelp (Ecklonia spp.). This type of high energy coastal habitat is regularly subjected to swell and winter storms, and so is considered highly resistant to damage from rock lobster potting. The significant recent reductions in fishing effort will have reduced these risks even further5,6.
  • The incidental capture of juvenile sea lions, recognised as a management issue by the Western Australian Department of Fisheries, has resulted in the introduction of sea lion excluder devices in high-risk areas7. This has reduced captures of sea lions, and no captures were recorded since their introduction in 2010.
  • Entanglements between West Coast Rock Lobster Managed Fishery (Western Australia) fishing gear and migrating whales increased in recent years due to an increase in whale population and an extension in the fishing season. As a result, gear modifications were mandated in 2014 throughout the fishery during the whale migration (May−October). These modifications have significantly reduced interactions with whales by approximately 60 per cent.
  • Sea lions, seals and sharks have been found to be particularly susceptible to injury or death through entanglement in uncut plastic bait bands. Historically, these bands also contribute to plastic debris washed up on shorelines. In 2012, a state-wide ban on the carriage of bait bands out to sea was implemented.
  • Research monitoring of commercial bycatch occurs continuously across the fishery; no issues of concern have been identified6.
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Environmental effects on Western Rock Lobster

  • Annual variation in the abundance of puerulus (post-larval lobsters) has historically been associated with fluctuations in offshore water temperatures during the early larval phase; water temperatures are influenced by the strength of the Leeuwin Current and the incidence of storm fronts crossing the west coast during spring8. More recently, other factors, such as timing of the onset of spawning (which is affected by water temperature), have been identified as possible contributors to these variations—in particular, the 7 years of below-average settlement (2006–07 to 2012–13), including the record low settlement of 2008–096,9,10.
  • Many aspects of the Western Rock Lobster life history, such as growth, migration, size at maturity and catchability, appear to be sensitive to changes in water temperature11–13. Increasing trends in long-term water temperature have co-occurred with declines in the size at maturity13 and size at migration11, and an increase in the proportion of female lobsters moulting out of setose in autumn12.
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References

  1. 1 Thompson, AP, Hanley, JR and Johnson, MS 1996, Genetic structure of the Western Rock Lobster, Panulirus cygnus, with the benefit of hindsight, Marine and Freshwater Research, 47: 889–896.
  2. 2 Johnson, MS 1999, Temporal variation of recruits as a basis of ephemeral genetic heterogeneity in the Western Rock Lobster, Panulirus cygnus, Marine Biology, 135: 133–139.
  3. 3 de Lestang, S, Caputi, N, How, J, Thomson, A and Stephenson, P 2012, Stock assessment for the West Coast Rock Lobster Fishery, Fisheries Research Report 217, Western Australian Department of Fisheries, Perth.
  4. 4 Webster, FJ, Dibden, DJ, Weir, KE and Chubb, CF 2002, Towards an assessment of the natural and human use impacts on the marine environment of the Abrolhos Islands, Fisheries Research Report 134, Western Australian Department of Fisheries, Perth.
  5. 5 Caputi, N, de Lestang, S, Reid, C, Hesp, A and How, J 2015, Maximum economic yield of the western rock lobster fishery of Western Australia after moving from effort to quota control,  Marine Policy, 51: 452–464.
  6. 6 Fletcher, WJ and Santoro, K (ed.s) 2013, Status reports of the fisheries and aquatic resources of Western Australia 2013/14, Western Australian Department of Fisheries, Perth.
  7. 7 Campbell, R 2005, Report for the sea lion scientific reference group, Fisheries Occasional Paper 16, Western Australian Department of Fisheries, Perth.
  8. 8 Caputi, N, Feng, M, de Lestang, S, Denham, A, Penn, J, Slawinski, D, Pearce, A, Weller, E and How, J 2014, Identifying factors affecting the low western rock lobster puerulus settlement in recent years, Final FRDC report—Project 2990/18, Fisheries Research Report 255, Western Australian Department of Fisheries, Perth.
  9. 9 Caputi, N, Chubb, CF and Pearce, A 2001, Environmental effects on recruitment of the western rock lobster, Panulirus cygnus, Marine and Freshwater Research, 52: 1167–1175.
  10. 10 de Lestang, S, Caputi, N, Feng, M, Denham, A, Penn, J, Slawinski, D, Pearce, A and How, J 2014, What caused seven consecutive years of low puerulus settlement in the western rock lobster fishery of Western Australia? ICES Journal of Marine Science, 72: 149–158.
  11. 11 Caputi, N, Melville-Smith, R, de Lestang, S, Pearce, A and Feng, M 2010, The effect of climate change on the Western Rock Lobster (Panulirus cygnus) fishery of Western Australia, Canadian Journal of Fish and Aquatic Sciences, 67: 85–96.
  12. 12 de Lestang, S and Melville-Smith, R 2006, Interannual variation in the moult cycle and size at double breeding of mature female western rock lobster (Panulirus cygnus), ICES Journal of Marine Science, 63: 1631–1639.
  13. 13 Melville-Smith, R and de Lestang, S 2006, Spatial and temporal variation in the size at maturity of the western rock lobster Panulirus cygnus George, Marine Biology, 150: 183–195.

Archived reports

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