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Red Emperor

Lutjanus sebae

  • Stephen Newman (Department of Fisheries, Western Australia)
  • Corey Wakefield (Department of Fisheries, Western Australia)
  • Julie Martin (Department of Primary Industry and Resources, Northern Territory)
  • Malcolm Keag (Department of Agriculture and Fisheries, Queensland)

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Western Australia Gascoyne GDSMF, WCDSIMF Sustainable Age structure, fishing mortality rates of indicator species
Western Australia Kimberley NDSMF Sustainable Spawning stock level; age structure, catch, CPUE
Western Australia Pilbara PTMF, PFTIMF Sustainable Spawning stock level; age structure, catch, CPUE
GDSMF
Gascoyne Demersal Scalefish Managed Fishery (WA)
NDSMF
Northern Demersal Scalefish Managed Fishery (WA)
PTMF, PFTIMF
Pilbara Trap Managed Fishery, Pilbara Fish Trawl (Interim) Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)
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Stock Structure

Red Emperor is exploited primarily in the North Coast Bioregion of Western Australia1. Smaller catches are taken in the Northern Territory and Queensland. Red Emperor is one of the indicator species used to assess the status of the demersal resources in the North Coast Bioregion. In Western Australia, analysis of otolith stable isotopes indicates that Red Emperor comprises a number of separate biological stocks, one in each of the main management regions, the Kimberley, the Pilbara and the Gascoyne2,3. Reporting of status is undertaken at the level of these individual biological stocks in Western Australia. Because multiple stocks are present within Western Australia, there is a high likelihood of multiple stocks across the Northern Territory and Queensland. However, stock delineation is not currently known in these jurisdictions. In the Northern Territory, status is reported at the jurisdictional level, while in Queensland, status is reported at the level of management units.

 

Here, assessment of stock status is presented at the biological stock level—Gascoyne, Pilbara and Kimberley (Western Australia); the jurisdictional level—Northern Territory; and the management unit level—Gulf of Carpentaria and East coast (Queensland).

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Stock Status

Gascoyne

The Gascoyne biological stock of Red Emperor is exploited as a component of the Gascoyne Demersal Scalefish Managed Fishery (Western Australia) (GDSMF)1. Red Emperor is assessed on the basis of the status of several indicator species (Snapper–Chrysophys auratus, Goldband Snapper—Pristipomoides multidens, Spangled Emperor–Lethrinus nebulosus) that represent the inshore demersal suite of species occurring at depths of 30–250 m. The major performance measures for these indicator species are either estimates of current spawning stock biomass levels or fishing mortality based assessments. The target level of spawning biomass is 40 per cent of the unfished level, and the limit level is 30 per cent of the unfished level. Indicator species assessments using an integrated age-structured model estimated that the spawning biomass levels of Snapper were close to 40 per cent of the unfished level in the GDSMF in 20111. The catch of Red Emperor in the Gascoyne is very low (11 tonnes [t]). The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished.

 

Fishing mortality based assessments1 (derived from catch curve analysis of representative samples of the age structure) indicated that the levels of F on the indicator species Goldband Snapper and Spangled Emperor were either lower than the target level, or above the limit level in some areas. This level of fishing pressure is unlikely to cause the stock to become recruitment overfished.

Based on the evidence provided above, the Gascoyne (Western Australia) biological stock is classified as a sustainable stock.

Pilbara

The major performance measures for the Pilbara biological stock landed in the Pilbara Trap Managed Fishery and Pilbara Fish Trawl Interim Managed Fishery are similar to those in the Northern Demersal Scalefish Fishery, and are based on estimates of current spawning stock levels of Red Emperor. The target level of spawning biomass is 40 per cent of unfished (1972) biomass. The limit level is 30 per cent of the unfished spawning biomass. The spawning biomass level of Red Emperor overall (across all management areas) was greater than 40 per cent in the Pilbara Demersal Scalefish Fisheries in 2007 (the year the last integrated assessment was undertaken), using an integrated age structured model4. The most recent assessment (2007) estimates that biomass in 2007 was 40 per cent of the unfished (1972) level. The stock is not considered to be recruitment overfished.

An assessment of fishing mortality derived from representative samples of the age structure of Red Emperor has also been undertaken for separate management areas in the Pilbara biological stock in 2007. These fishing mortality based assessments utilise the reference levels defined above for the Gascoyne biological stock. The fishing mortality based assessments indicated that the fishing level on Red Emperor in 2007 was between the target and the threshold level, but above the limit level in some areas4. This indicates that fishing was having an impact on the age structure of the population in some management areas. Effort reductions since 2008 have resulted in decreasing catch levels. In 2007, the Red Emperor catch from the Pilbara biological stock was 187 t. From 2008–10 the Red Emperor catch ranged from 154–167 t. In 2011, catches declined to 118 t and catches stabilised in the range of 50–61 t from 2012–14. In 2008–10, the catch rate trends of Red Emperor in all trawl managed areas increased each year. This was considered to be a response to the effort reductions imposed on the trawl fishery since 2008. In 2010–14 the catch rate trends of Red Emperor have been stable in all trawl managed areas, except Area 1, where there has been a slight decline. The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished.

Based on the evidence provided above, the Pilbara (Western Australia) biological stock is classified as a sustainable stock.

Kimberley

The major performance measures for the Kimberley biological stock of Red Emperor relate to spawning stock levels. The target level of spawning biomass is 40 per cent of unfished (1980) levels. The limit level is 30 per cent of the unfished levels. The spawning biomass level of Red Emperor was approximately 38 per cent in the Northern Demersal Scalefish Fishery (NDSF) in 2015 (the year the last integrated assessment was undertaken), as derived by synthesising the available data in an integrated age structured model4. Catch levels of Red Emperor in the NDSF over the past 5 years (2010–14) have been stable, ranging between 128 and 142 t, and are below the catch levels obtained for the preceding 5-year period (2005–09) of sustainable fishing, when catches ranged between 156 and 192 t4. From 2010–13 the catch rate trends of Red Emperor have been stable. The most recent assessment estimates that biomass in 2015 was 38 per cent of the unfished (1980) level. The stock is not considered to be recruitment overfished.

An assessment of fishing mortality derived from representative samples of the age structure of Red Emperor has also been undertaken for the NDSF in 2006, 2008 and 2012. These fishing mortality based assessments utilise reference levels defined above for the Gascoyne biological stock. The fishing mortality based assessments indicated that the fishing level on Red Emperor was close to the target reference level in 20124. This indicates that fishing is not having an unacceptable impact on the age structure of the population. The above evidence indicates that the biomass of this stock is unlikely to be recruitment overfished.

Based on the evidence provided above, the Kimberley (Western Australia) biological stock is classified as a sustainable stock.

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Biology

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Red Emperor 40–45 years; 800 mm FL  (860 mm TL) 4–6 years; 430–460 mm FL (460–490 mm TL)

Red Emperor biology5,8–10

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Distributions

Distribution of reported commercial catch of Red Emperor

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Tables

Fishing methods
Western Australia
Commercial
Various
Recreational
Spearfishing
Hand Line, Hand Reel or Powered Reels
Management methods
Method Western Australia
Commercial
Effort limits
Gear restrictions
Limited entry
Size limit
Spatial closures
Spatial zoning
Total allowable catch
Total allowable effort
Vessel restrictions
Indigenous
Laws of general application
Recreational
Bag limits
Licence
Limited entry
Passenger restrictions
Possession limit
Size limit
Spatial closures
Spatial zoning
Active vessels
Western Australia
16 in GDSMF, 8 in NDSMF, 5 in WCDGDLIMF, 37 in WCDSCMF
GDSMF
Gascoyne Demersal Scalefish Managed Fishery (WA)
NDSMF
Northern Demersal Scalefish Managed Fishery (WA)
WCDGDLIMF
West Coast Demersal Gillnet and Demersal Longline (Interim) Managed Fishery (WA)
WCDSCMF
West Coast Deep Sea Crustacean Managed Fishery (WA)
Catch
Western Australia
Commercial 10.61t in GDSMF, 131.69t in NDSMF, 4.35t in WCDSIMF
Indigenous Unknown
Recreational 9.15 t, 18.91 t
GDSMF
Gascoyne Demersal Scalefish Managed Fishery (WA)
NDSMF
Northern Demersal Scalefish Managed Fishery (WA)
WCDSIMF
West Coast Demersal Scalefish (Interim) Managed Fishery (WA)

Indigenousb,c

a Queensland – Commercial (fishing methods) In Queensland, Golden Snapper is trawled in only one of the Queensland fisheries in which it is caught commercially - the Gulf of Carpentaria Developmental Fin Fish Trawl Fishery

b In Queensland, data for the Coral Reef Fin Fish Fishery and Deep Water Fin Fish Fishery relates to the 2014–15 financial year. Data for the Gulf of Carpentaria Line Fishery and Gulf of Carpentaria Developmental Fin Fish Trawl Fishery are for the 2015 calendar year.

c In Queensland, under the Fisheries Act 1994 (Qld), indigenous fishers are entitled to use prescribed traditional and non-commercial fishing apparatus in waters open to fishing. Size and possession limits and seasonal closures do not apply to Indigenous fishers. Further exemptions to fishery regulations may be applied for through permits.

d Western Australia- Recreational (catch) Boat-based recreational catch from 1 May 2013–30 April 2014.

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Catch Chart

Commercial catch of Red Emperor

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Effects of fishing on the marine environment

  • The maintenance of high levels of biomass of Red Emperor in each of the fisheries in Western Australia results in a negligible eco-trophic risk from these fisheries. Furthermore, there has been no reduction in either mean trophic level or mean maximum length in the finfish catches recorded within the Pilbara or Kimberley in Western Australia (that is, no indication of fishing down of the food web)11.
  • Available information indicates that there are minimal impacts on habitat from trap or line based fishing methods for Red Emperor4.
  • Impacts to the habitat from trawling are expected to be minimal as trawling is restricted to only seven per cent of the north-west shelf and parts of the Northern Territory. Trawling does not occur in the Kimberley region1,4,8. Trawl nets in the Northern Territory have been designed to fish off the sea bed, reducing interaction with benthic habitats12.
  • The bycatch of dolphins and turtles has been reduced significantly since the introduction of exclusion grids in Pilbara fish trawl nets in 2005. Given the area of distribution and expected population size of these protected species, the impact of the fish trawl fishery on the stocks of these protected species is likely to be minimal15,16. Gear and fishing modification continue to reduce this level of interaction1,4,15.
  • The main Western Australian fisheries that target Red Emperor have received either full Export Exemption or Approved Wildlife Trade Operation Exemption accreditation under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The Northern Territory fisheries that target Red Emperor have received full Export Exemption accreditation under the Australian EPBC Act. The Queensland fisheries that target Red Emperor have received an Approved Wildlife Trade Operation Exemption accreditation under the EPBC Act. These assessments, subject to adherence to accompanying conditions and recommendations, demonstrate that these fisheries are managed in a manner that does not lead to overfishing, and that fishing operations have a minimal impact on the structure, productivity, function and biological diversity of the ecosystem.
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Environmental effects on Red Emperor

  • Climate change and climate variability has the potential to impact fish stocks in a range of ways including influencing their geographic distribution (for example, latitudinal shifts in distribution). However, it is unclear how climate change may affect risks to sustainability for this species.
  • Changes in oceanographic conditions have the potential to impact on the replenishment rates of fish populations and also to impact on individual growth rates and spawning output13.
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References

  1. 1 Fletcher, WJ and Santoro, K (eds.) 2015, Status Reports of the Fisheries and Aquatic Resources of Western Australia 2014/15: The State of the Fisheries, Department of Fisheries, Western Australia, Perth, Australia. 353p. http://www.fish.wa.gov.au/Documents/sofar/status_reports_of_the_fisheries_and_aquatic_resources_2014–15.pdf
  2. 2 Stephenson, PC, Edmonds, JS, Moran, MJ and Caputi, N 2001, Analysis of stable isotopes to investigate stock structure of red emperor and Rankin cod in northern Western Australia, Journal of Fish Biology, 58: 126–144.
  3. 3 van Herwerden, L, Aspden, WJ, Newman, SJ, Pegg, GG, Briskey, L and Sinclair, W 2009, A comparison of the population genetics of Lethrinus miniatus and Lutjanus sebae from the east and west coasts of Australia: evidence for panmixia and isolation, Fisheries Research, 100 (2): 148–155.
  4. 4 Newman, SJ, Wakefield, C, Skepper, C, Boddington, D, Blay, N, Jones, R and Dobson, P 2015, North Coast Demersal Fisheries Status Report. pp. 189–206. In: Fletcher, WJ and Santoro, K (eds.) 2015, Status Reports of the Fisheries and Aquatic Resources of Western Australia 2014/15: The State of the Fisheries, Department of Fisheries, Western Australia, Perth, Australia. 353p. http://www.fish.wa.gov.au/Documents/sofar/status_reports_of_the_fisheries_2014–15_north_coast_bioregion.pdf
  5. 5 O’Neill, MF, Leigh, GM, Martin, JM, Newman, SJ, Chambers, M, Dichmont, CM and Buckworth, RC 2011, Sustaining productivity of tropical red snappers using new monitoring and reference points, Final Report to the Fisheries Research and Development Corporation, Project 2009/037. 104p. http://www.frdc.com.au/documentlibrary/finalreports/2009–037–DLD.pdf
  6. 6 Leigh, GM and O'Neill, MF 2016, Gulf of Carpentaria Finfish Trawl Fishery: Maximum Sustainable Yield, Agi–Science Queensland, Department of Agriculture and Fisheries, Queensland.
  7. 7 Webley, J, McInnes, K, Teixeira, D, Lawson, A and Quinn, R 2015, Statewide Recreational Fishing Survey 2013–14, Queensland Department of Agriculture and Fisheries, Brisbane.
  8. 8 Newman, SJ and Dunk, IJ 2002, Growth, age validation, mortality, and other population characteristics of the red emperor snapper, Lutjanus sebae (Cuvier, 1828), off the Kimberley coast of North–Western Australia, Estuarine, Coastal and Shelf Science,55 (1): 67–80.
  9. 9 Newman, SJ, Skepper, CL and Wakefield, CB 2010, Age estimation and otolith characteristics of an unusually old, red emperor snapper (Lutjanus sebae) captured off the Kimberley coast of north–western Australia, Journal of Applied Ichthyology, 26 (1): 120–122.
  10. 10 Newman, SJ, Moran, MJ and Lenanton, RCJ 2001, Stock assessment of the outer–shelf species in the Kimberley region of tropical Western Australia, final report to the Fisheries Research and Development Corporation, project 97/136.
  11. 11 Hall, NG and Wise, BS 2011, Development of an ecosystem approach to the monitoring and management of Western Australian fisheries, Fisheries Research and Development Corporation Report, Project 2005–063, Fisheries Research Report 215, Western Australian Department of Fisheries, Perth.
  12. 12 Northern Territory Government 2015, Status of Key Northern Territory Fish Stocks Report 2013. Northern Territory Government, Department of Primary Industry and Fisheries, Fishery Report No. 114.
  13. 13 Johnson, JE and Welch, DJ 2010, Marine Fisheries Management in a Changing Climate: A Review of Vulnerability and Future Options, Reviews in Fisheries Science, 18 (1): 106–124.
  14. 14 Wakefield, CS, Santana-Garcon, J, Dorman, SR, Blight, S, Denham, A, Wakeford, J, Molony, BW and
  15. 15 Newman, SJ 2016, Performance of bycatch reduction devices varies for chondrichthyan, reptile, and cetacean mitigation in demersal fish trawls: assimilating subsurface interactions and unaccounted mortality, ICES Journal of Marine Science in press
  16. 16 Molony, BW, Wakefield, CB, Newman, SJ, O’Donoghue, S, Joll, L and Syers, C 2015, The need for a broad perspective concerning fisheries interactions and bycatch of marine mammals, pp.65-78, In: Kruse, GH, An, HC, DiCosimo, J, Eischens, CA, Gislason, GS, McBride, DN, Rose, CS and Siddon, CE (eds.). Fisheries Bycatch: Global Issues and Creative Solutions. Alaska Sea Grant, University of Alaska Fairbanks.

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