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Baldchin Groper (2018)

Choerodon rubescens

  • David Fairclough (Department of Primary Industries and Regional Development, Western Australia)

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Summary

WA’s Baldchin Groper is officially recovering, responding to management plans put in place between 2007 and 2010 to address overfishing. Both the commercial and recreational take for the species have been halved to help rebuild stocks.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Western Australia Western Australia GDSMF, JASDGDLMF, SBBSMNMF, WCDGDLIMF, WCDSIMF Recovering Spawning potential ratio, fishing mortality rate, catch
GDSMF
Gascoyne Demersal Scalefish Managed Fishery (WA)
JASDGDLMF
Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery (Zone 1 & Zone 2) (WA)
SBBSMNMF
Shark Bay Beach Seine and Mesh Net Managed Fishery (WA)
WCDGDLIMF
West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)
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Stock Structure

Analyses of microsatellite DNA indicates that Baldchin Groper comprises a single biological stock in Western Australia, occurring primarily in the West Coast Bioregion (WCB) south of 27°S latitude and west of 115°30´E longitude [Fairclough et al. 2011, Gardner et al. 2015].

Here, assessment of stock status is presented at the biological stock level—Western Australia.

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Stock Status

Western Australia

The Western Australian Department of Primary Industries and Regional Development uses fishing mortality (F) based assessments for data-limited species that compare to reference levels (target, threshold and limit) based on ratios of natural mortality (M) (Ftarget = 2/3M, Fthreshold = M and Flimit = 3/2M; [Wise et al. 2007]). An assessment in 2007 found that F estimated using linear catch curves for the Western Australia biological stock of Baldchin Groper exceeded the threshold, i.e. F = ~0.28, M = 0.21 [Department of Fisheries 2015, Wise et al. 2007]. External review supported the finding that this and other assessed indicator species in the demersal resource in the WCB (West Australian Dhufish and Snapper; [Newman et al. 2018]) had been experiencing recruitment overfishing [O’Neill 2009, Wise et al. 2007].

Changes to the management of fishing for demersal species, including Baldchin Groper, by both the commercial and recreational sectors in the WCB, were introduced between late-2007 and early-2010. These were designed to reduce retained catches by each sector in the WCB by at least 50 per cent of 2005–06 levels to allow recovery of stocks, such that F would fall below the threshold level (M). The 50 per cent catch reduction levels equate to 22 tonnes (t) and 33 t for the commercial and recreational sectors in the WCB, respectively.

Using methods of estimating fishing mortality that take into account recruitment variation [Fisher, 2013], an assessment of age structure data for Baldchin Groper from 2007–08 to 2010–11 (overlapping the period of management change), and a re-assessment of previous age structure data sets, indicated that F estimates had been above the limit reference point (F = 0.39–0.41, 1993–95; 2000–02) and were above the limit in 2007/08–2010/11 (F = 0.51). The spawning potential ratio (0.24) was between the limit (SPR0.2) and threshold (SPR0.3) in each of those periods [Fairclough et al. 2014].

Annual commercial catches of Baldchin Groper in the WCB have remained below 50 per cent of 2005–06 catch levels (22 t) since 2008 [Fairclough et al. 2018], not exceeding 19 t in any year. Commercial catch in recent years declined further as a result of reductions in effort entitlements in 2015 in the West Coast Demersal Scalefish (Interim) Managed Fishery and unit entitlements of the West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery. These were to limit catches of the West Coast Snapper stock to facilitate its recovery [see Fowler et al. 2018]. Estimated recreational sector catches of Baldchin Groper (biennial estimates for private recreational boat-based fishers [Ryan et al. 2017], plus annual tour operator catches) between 2011–12 and 2015–16 ranged from 38–52 t. Eighty to 90 per cent of those were taken in the WCB (i.e. 31–47 t). These catches were close to or above the 33 t maximum retained catch levels that would allow stock recovery. Management is currently evaluating options to ensure catches do not continue to exceed that level to ensure recovery occurs.

An assessment of indicator species (West Australian Dhufish and Snapper) for the demersal resource in the WCB, which includes Baldchin Groper, was conducted in 2017 (based on 2012–13 to 2014–15 data). Baldchin Groper is assessed aperiodically. Estimated F values for Western Australian Dhufish (F = 0.21) and Snapper (F = 0.23) were above their limit reference points (F = 0.165, 0.18, respectively) and spawning potential ratios were between the limit and threshold for Western Australian Dhufish (SPR = 0.2–0.3) and below the limit of SPR = 0.2 for Snapper [Department of Primary Industries and Regional Development, unpublished data]. That assessment was based on age composition data collected just after management changes were completed. Thus, it was not expected to demonstrate significant change, given the longevity of these species [Hesp et al. 2002, Norriss and Crisafulli 2010] and the likelihood that recovery would take ~20 years [Wise et al. 2007]. However, additional estimates of F were derived using a method that allows for a change in fishing mortality, i.e. for cohorts of fish that have recruited to a fishery pre- and post-management changes [Fisher 2013]. For the small number of age classes in the 2012–13 to 2014–15 data for West Australian Dhufish and Snapper that recruited to the fishery after management changes commenced in 2008, F estimates were lower than for age classes recruited to the fishery prior to management changes, i.e. F = 0.13 vs 0.21 for Western Australian Dhufish and F = 0.14 vs 0.27 for Snapper. This suggests that recovery of these species had commenced and, as indicators of the status of the resource, it is assumed that is also the case for Baldchin Groper [Department of Primary Industries and Regional Development unpublished data, Newman et al. 2018]. The above evidence indicates that at the time of the first assessment in 2007, the biomass of the Western Australia biological stock of Baldchin Groper was likely to have been depleted and recruitment was likely to have been impaired. However, from the most recent assessment, the above evidence indicates that the current level of fishing mortality should allow the stock to recover from its recruitment impaired state.

On the basis of the evidence provided above, the Western Australia biological stock is classified as a recovering stock.

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Biology

Baldchin Groper biology [Fairclough et al. 2014, Fairclough 2005, Nardi et al. 2006]

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Baldchin Groper ~25 years, ~700 mm TL Female maturity: 4 years, 279 mm TL Protogynous sex change (to male): 12 years, 479 mm TL
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Distributions

Distribution of reported commercial catch of Baldchin Groper

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Tables

Fishing methods
Western Australia
Commercial
Hand Line, Hand Reel or Powered Reels
Hook and Line
Dropline
Gillnet
Haul Seine
Unspecified
Indigenous
Spearfishing
Traditional apparatus
Handline
Recreational
Spearfishing
Handline
Management methods
Method Western Australia
Charter
Bag limits
Gear restrictions
Limited entry
Marine park closures
Passenger restrictions
Size limit
Spatial closures
Temporal closures
Commercial
Catch limits
Effort limits
Gear restrictions
Limited entry
Size limit
Spatial closures
Vessel restrictions
Indigenous
Bag limits
Gear restrictions
Possession limit
Size limit
Spatial closures
Temporal closures
Recreational
Bag limits
Gear restrictions
Licence (fishing from a boat)
Marine park closures
Possession limit
Size limit
Spatial closures
Temporal closures
Active vessels
Western Australia
53 in Charter, 7 in GDSMF, <3 in JASDGDLMF, <3 in SBBSMNMF, 5 in WCDGDLIMF, 35 in WCDSIMF
Charter
Tour Operator (WA)
GDSMF
Gascoyne Demersal Scalefish Managed Fishery (WA)
JASDGDLMF
Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery (Zone 1 & Zone 2) (WA)
SBBSMNMF
Shark Bay Beach Seine and Mesh Net Managed Fishery (WA)
WCDGDLIMF
West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)
Catch
Western Australia
Commercial 7.71t in GDSMF, JASDGDLMF, SBBSMNMF, WCDGDLIMF, WCDSIMF
Charter 13 t (2015–16)
Indigenous Unknown
Recreational 39 t (± 4 t se; 2015–16)
GDSMF
Gascoyne Demersal Scalefish Managed Fishery (WA)
JASDGDLMF
Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery (Zone 1 & Zone 2) (WA)
SBBSMNMF
Shark Bay Beach Seine and Mesh Net Managed Fishery (WA)
WCDGDLIMF
West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)

Western Australia – Commercial (catch) The GDSMF fishing season runs from 1 September–31 August.

Western Australia – Commercial (catch) The JASDGDLMF and WCDGDLIMF fishing seasons run from 1 June–31 May.

Western Australia – Commercial (catch) The WCDSIMF fishing season runs from 1 January–31 December.

Western Australia – Commercial (catch) The SBBSMNMF fishing season runs from 1 January–31 December.

Western Australia – Recreational (catch) The boat-based recreational catch is for a full year survey.

Western Australia – Recreational tour operator (catch) The recreational charter catch is for a full year from 1 July–30 June.

Western Australia – 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 those for recreational fishing.

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Catch Chart

Commercial catch of Baldchin Groper - note confidential catch not shown

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References

  1. Department of Fisheries 2015, Harvest strategy policy and operational guidelines for the aquatic resources of Western Australia, Fisheries Management Paper No. 271, Department of Fisheries, Perth.
  2. Fairclough, D 2005, The biology of four tuskfish species (Choerodon: Labridae) in Western Australia, PhD thesis, Murdoch University, Perth.
  3. Fairclough, D, Walters, S and Holtz, M 2018, West coast demersal scalefish resource status report 2017, in DJ Gaughan and K Santoro (eds), Status reports of the fisheries and aquatic resources of Western Australia 2016/17: The State of the Fisheries, Department of Primary Industries and Regional Development, Western Australia, Perth.
  4. Fairclough, DV, Edmonds, JS, Lenanton, RCJ, Jackson, G, Keay, IS, Crisafulli, BM and Newman, SJ 2011, Rapid and cost-effective assessment of connectivity among assemblages of Choerodon rubescens (Labridae), using laser ablation ICP-MS of sagittal otoliths, Journal of Experimental Biology and Ecology, 403: 46–53.
  5. Fairclough, DV, Molony, BW, Crisafulli, BM, Keay, IS, Hesp SA and Marriott RJ 2014, Status of demersal finfish stocks on the west coast of Australia, Fisheries Research Report No. 253, Department of Fisheries Western Australia, Perth.
  6. Fisher, E 2013, Tools for assessing data-limited fisheries and communicating stock status information, PhD thesis, Murdoch University Perth.
  7. Fowler, A, Jackson, G, Stewart, J, Hamer, P and Roelofs, A 2018, Snapper Chrysophrys auratus In Status of Key Australian Fish Stocks, Fisheries Research and Development Corporation, Canberra.
  8. Gardner, MJ, Chaplin, JA, Potter, IC and Fairclough DV 2015, Pelagic early life stages promote connectivity in the demersal labrid Choerodon rubescens, Journal of Experimental Biology and Ecology, 472: 142–150.
  9. Hesp, SA, Potter, IC and Hall, NG 2002, Age and size composition, growth rate, reproductive biology, and habitats of the West Australian Dhufish (Glaucosoma hebraicum) and their relevance to the management of this species, Fishery Bulletin, 100: 214–227.
  10. Nardi, K, Newman, SJ, Moran, MJ and Jones GP 2006, Vital demographic statistics and management of the baldchin groper (Choerodon rubescens) from the Houtman Abrolhos Islands, Marine and Freshwater Research 57: 485–496
  11. Newman, SJ, Brown, JI, Fairclough, DV, Wise, BS, Bellchambers, LM, Molony, BW, Lenanton, RCJ, Jackson, G, Smith, KA, Gaughan, DJ, Fletcher, WJ, McAuley, RB and Wakefield, CB 2018, A risk assessment and prioritisation approach to the selection of indicator species for the assessment of multi-species, multi-gear, multi-sector fishery resources, Marine Policy 88: 11–22.
  12. Norriss, JV and Crisafulli, B 2010, Longevity in Australian snapper Pagrus auratus (Sparidae), Journal of the Royal Society of Western Australia, 93: 129–132
  13. O’Neill, M 2009, Scientific review of the West Coast Demersal Scalefish Fishery, Western Australia, Fisheries Occasional Publication No. 66, Department of Fisheries Western Australia, Perth.
  14. Ryan, KL, Hall, NG, Lai, EK, Smallwood, CB, Taylor, SM and Wise, BS 2017, Statewide survey of boat-based recreational fishing in Western Australia 2015/16. Fisheries research Report No. 287. Department of Primary Industries and Regional Development, Government of Western Australia, Perth.
  15. Wise, BS, St John, J and Lenanton, RC (eds) 2007, Spatial scales of exploitation among populations of demersal scalefish: implications for management, Part 1: Stock status of the key indicator species for the Demersal Scalefish Fishery in the West Coast Bioregion. Fisheries Research Report No. 163, Department of Fisheries, Western Australia, Perth.