*

Blue Grenadier

Macruronus novaezelandiae

  • Lee Georgeson (Australian Bureau of Agricultural and Resource Economics and Sciences)

You are currently viewing a report filtered by jurisdiction. View the full report.

Toggle content

Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Commonwealth Commonwealth Trawl Sector SESSF (CTS) Sustainable Spawning stock biomass, fishing mortality
Commonwealth Great Australian Bight Trawl Sector SESSF (GABTS) Sustainable Current and historical fishing pressure
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
SESSF (GABTS)
Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (CTH)
Toggle content

Stock Structure

Comparative analysis of otolith chemistry and shape indicates two biological stocks of Blue Grenadier: one in the region of the Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (Commonwealth) and the other in the region of the Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (Commonwealth) (SESSF [CTS])1. There is some evidence that Blue Grenadier from the western Tasmanian and eastern Bass Strait regions of the SESSF (CTS) may constitute separate sub-stocks, but these are currently assessed and managed as a single Commonwealth Trawl Sector stock2.

Here, assessment of stock status is presented at the biological stock level—Commonwealth Trawl Sector and Great Australian Bight Trawl Sector (Commonwealth).

Toggle content

Stock Status

Commonwealth Trawl Sector

Blue Grenadier in the Commonwealth Trawl Sector (SESSF [CTS]) and the Gillnet, Hook and Trap Sector (Commonwealth) (SESSF [GHTS]) of the Southern and Eastern Scalefish and Shark Fishery (Commonwealth) is managed under a multiyear total allowable catch (TAC). The SESSF (CTS) accounts for the majority of the catch. Given the relatively low catch from the SESSF (GHTS) from the area of the SESSF (CTS), the biological stock is referred to in this report as the Commonwealth Trawl Sector biological stock.

The Blue Grenadier stock assessment was updated in 2013 with new catch-at-age and catch rate data up to 2012, as well as estimates of spawning biomass from acoustic surveys (industry-based) and egg survey indices of female spawning biomass3. The assessment estimated a large recruitment event in 2010. The stock was assessed as being above the target reference point at 77 per cent of unfished biomass in 2012, and trending upwards. This stock is not considered to be recruitment overfished4.

Blue Grenadier was managed under multiyear TACs of 4700 tonnes (t) for the 2009–10 to 2011–12 seasons, and 5208 t for the 2012–13 and 2013–14 seasons. The 2013 assessment estimated an increased 3-year recommended biological catch of 8810 t, starting in 2014–15. A 2014–15 TAC of 6800 t was implemented after consideration of industry's preference for a cautious approach to increasing the TAC, to promote economic stability5. The multiyear TAC increased to 8796 t in the 2015–16 season. Reported landings in 2015–16 were 1754 t, of which 1745 t was taken in the SESSF (CTS). Discard estimates have been variable, ranging between six per cent in 2012 and 32 per cent in 20146. Discard estimates are not yet available for 2015. This level of fishing pressure is unlikely to cause the stock to become recruitment overfished.

On the basis of the evidence provided above, the Commonwealth Trawl Sector biological stock is classified as a sustainable stock.

Great Australian Bight Trawl Sector

There have been no stock assessments for the Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (Commonwealth) biological stock of Blue Grenadier, and no estimates of fishing mortality or biomass have been made. A catch trigger of 400 t is in place; if this is exceeded, data collection and the development of an assessment plan are required. A cease-to-fish catch trigger of 500 t also applies7.

This Blue Grenadier biological stock is targeted on the upper continental slope (around 200–700 m). Fishing effort on the Great Australian Bight continental slope has decreased since 2005, with commercial catches of Blue Grenadier reducing from a peak catch of 423 t in 2005–06 to a low of 3 t in 2015–16. There are large areas of slope habitat across the Great Australian Bight and Western Australia, with fishing generally limited to a small area. It is therefore likely that parts of this biological stock remain unfished. 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 Great Australian Bight Trawl Sector (Commonwealth) biological stock is classified as a sustainable stock.

Toggle content

Biology

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Blue Grenadier 25 years; 1 100 mm TL , weight 6 kg 4–5 years, females 640 mm TL, males 570 mm TL

Blue Grenadier biology1

Toggle content

Distributions

Distribution of reported commercial catch of Blue Grenadier

Toggle content

Tables

Fishing methods
Commonwealth
Commercial
Otter Trawl
Midwater Trawl
Recreational
Hand Line, Hand Reel or Powered Reels
Management methods
Method Commonwealth
Commercial
Limited entry
Spatial closures
Total allowable catch
Trigger limits
Active vessels
Commonwealth
38 in SESSF (CTS), 3 in SESSF (GABTS), 18 in SESSF (GHTS)
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
SESSF (GABTS)
Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (CTH)
SESSF (GHTS)
Southern and Eastern Scalefish and Shark Fishery (Gillnet Hook and Trap Sector) (CTH)
Catch
Commonwealth
Commercial 1.74Kt in SESSF (CTS), 2.88t in SESSF (GABTS)
Indigenous Unknown
Recreational Unknown
SESSF (CTS)
Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (CTH)
SESSF (GABTS)
Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (CTH)

Recreationala Indigenousb

 

a The Commonwealth does not manage recreational fishing in Commonwealth waters. Recreational fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters, under its management regulations.

b The Australian government does not manage non-commercial Indigenous fishing in Commonwealth waters, with the exception of Torres Strait. In general, non-commercial Indigenous fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters.

Toggle content

Catch Chart

Commercial catch of Blue Grenadier

Toggle content

Effects of fishing on the marine environment

  • There is bycatch in the fish trawl sector. In 2006, mandatory requirements for otter trawls to use 90 mm square-mesh codend panels were introduced in an effort to reduce the catch of small species and juvenile fish8.
  • Interactions also occur with animals protected under the Environment Protection and Biodiversity Conservation Act 1999, including marine mammals (dolphins, seals and sea lions), seabirds, some shark species and seahorses and pipefish (syngnathids). These interactions are reported quarterly by the Australian Fisheries Management Authority (AFMA)9 and on-board observer programs are used to validate the reporting in commercial logbooks.
  • In 2007, the South East Trawl Fishing Industry Association released an industry code of practice that aims to minimise interactions with fur seals, as well as addressing the environmental impacts of the fishery more generally10. Operators have developed other mitigation protocols that have further reduced seal mortalities, including using breakaway ties that keep the net closed until it is below depths that seals regularly inhabit, adopting techniques to close the trawl opening during recovery to minimise opportunities for seals to enter the net, switching off gantry lights that are not required during night trawling to avoid attracting bait species and seals, and dumping offal only when the boat is not engaged in deploying or hauling gear10.
  • The AFMA mandated individual vessel seabird management plans11. The seabird action plans are used in the Southern and Eastern Scalefish and Shark Fishery (Commonwealth Trawl Sector) (SESSF [CTS]) to mitigate the impacts of trawling on seabirds. From 1 May 2017, all vessels in the SESSF (CTS) and Southern and Eastern Scalefish and Shark Fishery (Great Australian Bight Trawl Sector) (Commonwealth) (SESSF [GABTS]) fisheries must use one of the following mitigation devices: sprayers; bird bafflers; or pinkies with zero discharge of fish waste12.
  • The effects of trawl fishing on the marine environment are assessed through an environmental risk assessment and risk management framework and mitigated through spatial closures, and the implementation of bycatch and discard workplans13,14 in the SESSF (CTS) and SESSF (GABTS) fisheries.
Toggle content

Environmental effects on Blue Grenadier

  • Changes in ecosystem structure and function due to changes in climate may affect larval recruitment of Blue Grenadier15. Stock assessments indicate substantial interannual recruitment variability, with occasional years of very high recruitment, which are probably environmentally driven3.
Toggle content

References

  1. 1 Hamer, P, Kemp, J, Robertson, S and Hindell, J 2009, Use of otolith chemistry and shape to assess the stock structure of Blue Grenadier (Macruronus novaezelandiae) in the Commonwealth Trawl and Great Australian Bight fisheries, final report to the Fisheries Research and Development Corporation, project 2007/030, Fisheries Research Branch, Queenscliff.
  2. 2 Morison, AK, Knuckey, IA, Simpfendorfer, CA and Buckworth, RC 2013, South East Scalefish and Shark Fishery 2012 stock assessment summaries for species assessed by GABRAG, ShelfRAG and Slope/DeepRAG, report for the Australian Fisheries Management Authority, January 2013.
  3. 3 Tuck, GN 2014, Stock assessment of blue grenadier Macruronus novaezelandiae based on data up to 2012, in GN Tuck (ed.), Stock assessment for the Southern and Eastern Scalefish and Shark Fishery 2013, part 1, Australian Fisheries Management Authority and CSIRO Marine and Atmospheric Research, Hobart.
  4. 4 Georgeson, L, Nicol, S, Moore, A, and Green, R 2016, Commonwealth Trawl and Scalefish Hook sectors, in Patterson, H, Noriega, R, Georgeson, L, Stobutzki, I and Curtotti, R (ed.) 2016, Fishery status reports 2016, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, 135-230.
  5. 5 SEMAC 2014, 'South East Management Advisory Committee (SEMAC) minutes, meeting 14, 30–31 January 2014', Australian Fisheries Management Authority, Canberra.
  6. 6 Upston, J 2015, Integrated Scientific Monitoring Program for the Southern and Eastern Scalefish and Shark Fishery—discard estimation 2014, Australian Fisheries Management Authority and CSIRO Marine and Atmospheric Research, Hobart.
  7. 7 Australian Fisheries Management Authority 2008, Southern and Eastern Scalefish and Shark Fishery—Great Australian Bight Trawl Sector. Management arrangements booklet, AFMA, Canberra.
  8. 8 Australian Fisheries Management Authority 2005, SESSF direction no. 05: gear requirements for the Commonwealth Trawl Sector, AFMA, Canberra.
  9. 9 Australian Fisheries Management Authority, Protected species interaction reports, AFMA, Canberra.
  10. 10 South East Trawl Fishing Industry Association 2007, Industry code of practice to minimise interactions with seals, SETFIA, Shearwater, Tasmania.
  11. 11 Australian Fisheries Management Authority, Seabirds, AFMA, Canberra.
  12. 12 AFMA 2016, AFMA moves to strengthen seabird safety, AFMA media release 15 July 2016.
  13. 13 Australian Fisheries Management Authority 2014, Commonwealth Trawl Sector (Otter Board Trawl and Danish Seine) bycatch and discarding workplan 2014 - 2016, AFMA, Canberra.
  14. 14 Australian Fisheries Management Authority 2014, Great Australian Bight Trawl Sector bycatch and discarding workplan 2014 – 2016, AFMA, Canberra.
  15. 15 Hobday, AJ, Poloczanska, ES and Matear, R 2007, Implications of climate change for Australian fisheries and aquaculture: a preliminary assessment, CSIRO Marine and Atmospheric Research report to the Australian Government Department of Climate Change, Canberra.

Archived reports

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc vel ornare magna, nec viverra ante. Ut in ipsum tellus.