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West Australian Dhufish (2020)

Glaucosoma hebraicum

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

Date Published: June 2021

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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 Stock status Indicators
Western Australia Western Australia Recovering

Catch, fishing mortality, spawning potential ratio

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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

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]). Spawning potential ratios (SPR) are determined from these F estimates.

Assessments in 2007 and 2009 demonstrated that F for the Western Australia biological stock of West Australian Dhufish exceeded the limit reference point (F=0.165) indicating this species may have been experiencing recruitment overfishing [Wise et al. 2007, Fairclough et al. 2009, O’Neill 2009]. Significant changes were made to the management of both the commercial and recreational sectors in the WCB between late 2007 and early 2010 to reduce catches in each sector by at least 50 per cent of 2005–06 levels (the 'stock recovery benchmarks'). This was designed to allow recovery of stocks, by reducing F to below the threshold level (F = 0.11). The stock recovery benchmarks are 82 tonnes (t) and 126 t for the commercial and recreational sectors in the WCB, respectively. 

The most recent estimated landings of West Australian Dhufish in Western Australia (which includes catches in the West and South Coast bioregions) comprised 64 t by the commercial sector in 2019 and 149 t by the recreational sector (private boat-based fishers and charter fishers) in 2017–18 [Ryan et al. 2019, Gaughan and Santoro, 2020]. 

In the WCB, where the majority of the catch of West Australian Dhufish is takentotal annual commercial catches have been below its stock recovery benchmark of 82 t since 2009 (e.g. 53 t in 2019). Catches of the primary commercial fishery for West Australian Dhufish (the West Coast Demersal Scalefish Interim Managed Fishery; WCDSIMF) have also been below its stock recovery benchmark of 72 t since effort limitations for this managed fishery commenced, e.g. 44 t landed in 2019 [Fairclough et al., 2020]. Recent lower commercial catches are also influenced by further reductions in 2015 in effort entitlements of the multi-species WCDSIMF and unit entitlements of the WCDGDLIMF to limit catches of Snapper in the WCB to below its commercial stock recovery catch benchmark (see Snapper: West Coast Stock report [Fowler et al. 2020]. 

In the WCB only, recreational sector catches (based on periodic estimates of catch ranges by boat-based recreational fishers, plus annual charter catch estimates) have been around or below the benchmark of 126 t since management changes were completed in early 2010. The most recent catch range estimate (95 per cent confidence limits) in the WCB in 2017–18 was 117–153 t. This comprised 123 t (95 per cent confidence interval = 105–141 t) by private boat-based fishers and 12 t by  charter fishers [Ryan et al. 2019, Fairclough et al. 2020]. Since management changes to recover stocks, release rates of West Australian Dhufish by the recreational sector have been relatively high (59% by boat based fishers in 2017–18 and 39% by charter fishers in 2018–19). Given an estimated average release mortality rate of 50% in cage-based experiments, high release rates would be resulting in additional fishing mortality on the stock [Ryan et al. 2019, Fairclough et al. 2020].

Assessments of West Australian Dhufish based on age structure data collected in 2008–09 to 2010–11 and 2012–13 to 2014–15 demonstrated that the estimated F (F = 0.21 y-1  in 2012–13 to 2014–15) remained above the limit reference point and SPR was between the limit and threshold (SPRlimit = 0.2, SPRthreshold = 0.3) [Fairclough et al., 2020]. As those assessments were based on age composition data collected during and just after the introduction of management changes,  they were not expected to demonstrate significant change, given the biological characteristics of West Australian Dhufish. For example, as a relatively long-lived species [Hesp et al. 2002], recovery would likely take ~20 years [Wise et al. 2007]. The above evidence indicates that the biomass of this stock was likely to be depleted and recruitment 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 [Fairclough et al., 2020]. 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
Line
Dropline
Gillnet
Longline (Unspecified)
Charter
Spearfishing
Rod and reel
Indigenous
Spearfishing
Hook and Line
Traditional apparatus
Unspecified
Recreational
Spearfishing
Hook and Line
Management methods
Method Western Australia
Charter
Bag limits
Boat limits
Gear restrictions
Licence
Limited entry
Marine park closures
Passenger restrictions
Possession limit
Size limit
Spatial zoning
Temporal closures
Commercial
Effort limits
Gear restrictions
Limited entry
Marine park closures
Size limit
Spatial closures
Spatial zoning
Total allowable effort
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
Catch
Western Australia
Commercial 63.68t
Charter 13 t
Indigenous Unknown
Recreational 136 t (2017–18)

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, and Walters, S 2020, West coast demersal scalefish resource status report 2019, in DJ Gaughan and K Santoro (eds), Status reports of the fisheries and aquatic resources of Western Australia 2018/19: The State of the Fisheries, Department of Primary Industries and Regional Development, Western Australia, Perth.
  3. 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.
  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. Fowler, A, Stewart, J, Victorian Fisheries Authority, Roelofs, A, Garland, A and Jackson, G 2020, Snapper. Status of Australian Fish Stocks.
  8. Gaughan, D and Santoro, K 2018, 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.
  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. 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.
  11. Ryan, KL, Hall, NG, Lai, EK, Smallwood, CB, Tate, A, Taylor, SM and Wise, BS 2019, Statewide survey of boat-based recreational fishing in Western Australia 2015/16. Fisheries Research Report No. 297. Department of Primary Industries and Regional Development, Government of Western Australia, Perth.
  12. 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.
  13. 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.

Downloadable reports

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