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West Australian Dhufish (2018)

Glaucosoma hebraicum

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

Western Australian Dhufish is found only in WA. It has a single biological stock that is assessed as recovering.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Western Australia Western Australia JASDGDLMF, WCDGDLIMF, WCDSIMF, WL (SC), FBLC74 Recovering Catch, fishing mortality, spawning potential ratio
FBLC74
Fishing Boat Licence Conditions (WA)
JASDGDLMF
Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery (Zone 1 & Zone 2) (WA)
WCDGDLIMF
West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)
WL (SC)
Open Access in the South Coast (WA)
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Stock Structure

Molecular analyses of microsatellite DNA indicates that West Australian Dhufish comprises a single biological stock in Western Australia, occurring primarily in the West Coast Bioregion (WCB) between 26°30′S latitude and 115°30′E longitude [Berry et al. 2012, Fairclough et al. 2013].

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

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Stock Status

Western Australia

Assessments completed in 2007 and 2009 demonstrated that fishing mortality (F) rates for the Western Australia biological stock exceeded the limit reference point of 1.5 times natural mortality (M) indicating this species may have been experiencing recruitment overfishing [Fairclough et al. 2009, O’Neill 2009, Wise et al. 2007]. Significant changes to the management of both the commercial and recreational sectors in the WCB were introduced between late-2007 and early-2010. These were designed to reduce retained catches in each sector by at least 50 per cent of 2005–06 levels to allow recovery of stocks, such that fishing mortality rates would fall below the threshold level of F = M. These 50 per cent catch reduction levels equate to 82 tonnes (t) and 126 t for the commercial and recreational sectors, respectively. An assessment of West Australian Dhufish based on age structure data collected in 2008–09 to 2010–11, overlapping the period of management change, indicated that at that time F estimates were still around or above the limit, while the spawning potential ratio (SPR) was between the limit and threshold [Fairclough et al. 2014].

Annual catches of West Australian Dhufish by the West Coast Demersal Scalefish Interim Managed Fishery (WCDSIMF) in the WCB have remained below 50 per cent of 2005–06 catch levels since 2009 [Fairclough et al., 2018], when effort limitations for this managed fishery commenced. Total commercial catches in the WCB have also been close to or below the benchmark of 82 t since 2009 and total commercial catches at the stock level in 2017 were 44 t. The decline in commercial catch in recent years is a result of reductions in effort entitlements of the WCDSIMF and unit entitlements of the WCDGDLIMF to limit catches of Snapper in the West Coast of Western Australia stock to its recovery benchmarks. Recreational sector catches in the WCB (based on biannual estimates of catch by recreational boat-based fishers [Ryan et al. 2017], plus annual charter catch estimates) have remained around or below the benchmark of 126 t since management changes were completed in early-2010. The most recent catch range estimate in the WCB in 2015–16 was 127 t (boat-based fishing 113 t, 95 per cent confidence interval = 97–129 t; charter fishing point estimate = 14 t) [Fairclough et al. 2018].

The most recent unpublished assessment from 2017 (based on 2012–13 to 2014–15 data) indicated that the estimated F of 0.21 year-1 remained above the limit reference point of 1.5M (0.165 year-1) and thus well above the threshold, and the SPR (0.15) was below the limit of SPR = 0.2 [Department of Primary Industries and Regional Development, unpublished data]. As that assessment was based on age composition data collected just after management changes were completed, it was not expected to demonstrate significant change, given the biological characteristics of West Australian Dhufish, for example, being long-lived [Hesp et al. 2002], and the likelihood that recovery would take ~20 years [Wise et al. 2007]. The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely to be impaired. However, using a method that takes into account a change in F as a result of management change [Fisher 2013], estimated F for age classes recruited to the fishery after management changes commenced in 2008 were lower than for age classes recruited to the fishery prior to management changes (i.e. F = 0.13 vs 0.27), indicating recovery had commenced [Department of Primary Industries and Regional Development, unpublished data]. 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

West Australian Dhufish biology [Hesp et al. 2002, Smallwood et al. 2013]

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
West Australian Dhufish ~41 years, ~1 220 mm  TL ~3 years Females ~300 mm TL Males ~320 mm TL
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Distributions

Distribution of reported commercial catch of West Australian Dhufish
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Tables

Fishing methods
Western Australia
Commercial
Hand Line, Hand Reel or Powered Reels
Hook and Line
Dropline
Gillnet
Unspecified
Fish Trap
Longline (Unspecified)
Indigenous
Spearfishing
Hook and Line
Traditional apparatus
Recreational
Spearfishing
Hook and Line
Management methods
Method Western Australia
Charter
Bag limits
Boat limits
Gear restrictions
Licence
Marine park closures
Passenger restrictions
Possession limit
Size limit
Spatial zoning
Temporal closures
Commercial
Effort limits
Gear restrictions
Limited entry
Size limit
Spatial closures
Vessel restrictions
Indigenous
Bag limits
Boat limits
Gear restrictions
Possession limit
Size limit
Temporal closures
Recreational
Bag limits
Boat limits
Gear restrictions
Licence (boat-based sector)
Marine park closures
Possession limit
Size limit
Spatial zoning
Temporal closures
Active vessels
Western Australia
52 in Charter, <3 in FBLC74, 9 in JASDGDLMF, 5 in WCDGDLIMF, 40 in WCDSIMF, 33 in WL (SC)
Charter
Tour Operator (WA)
FBLC74
Fishing Boat Licence Conditions (WA)
JASDGDLMF
Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery (Zone 1 & Zone 2) (WA)
WCDGDLIMF
West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)
WL (SC)
Open Access in the South Coast (WA)
Catch
Western Australia
Commercial 44.04t in FBLC74, JASDGDLMF, WCDGDLIMF, WCDSIMF, WL (SC)
Charter 13.29 t in Tour Operator
Indigenous Unknown
Recreational 113 t (±16 t se; 2015–16)
FBLC74
Fishing Boat Licence Conditions (WA)
JASDGDLMF
Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery (Zone 1 & Zone 2) (WA)
WCDGDLIMF
West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)
WL (SC)
Open Access in the South Coast (WA)

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 that for recreational fishing. Western Australia – Commercial (catch) (a) The GDSMF fishing season runs from 1 September–31 August; (b) The JASDGDLMF and WCDGDLIMF fishing seasons run from 1 June–31 May; (c) The WCDSIMF runs from 1 January–31 December; and (d) The WL(SC) fishery runs from 1 January–31 December.

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Catch Chart

Commercial catch of West Australian Dhufish - note confidential catch not shown
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References

  1. Berry, O, England, P, Fairclough, D and Jackson, G 2012, Microsatellite DNA analysis and hydrodynamic modelling reveal the extent of larval transport and gene flow between management zones in an exploited marine fish (Glaucosoma hebraicum), Fisheries Oceanography, 21: 243–254.
  2. Fairclough, D, Lai, E and Bruce, C 2009, West Coast Demersal Scalefish Fishery status report, in WJ Fletcher and K Santoro (ed.s) State of the fisheries report 2008–09, Department of Fisheries, Western Australia, Perth, pp 71–79.
  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, Jackson, G, Lenanton, RCJ, Kemp, J, Molony, BW, Keay, IS, Crisafulli, BM and Wakefield, CB 2013, A comparison of the stock structures of two exploited demersal teleosts, employing complementary methods of otolith element analysis, Journal of Experimental Marine Biology and Ecology, 439: 181–195.
  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. 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.
  8. 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.
  9. 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.
  10. Smallwood, CB, Hesp, SA and Beckley, LE 2013, Biology, stock status and management summaries for selected fish species in south-western Australia, Fisheries Research Report No. 242, Department of Fisheries, Western Australia, Perth.
  11. 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.