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Southern Sand Flathead

Platycephalus bassensis

  • James Andrews (Department of Economic Development, Jobs, Transport and Resources, Victoria)
  • Anthony Fowler (South Australian Research and Development Institute)
  • Jeremy Lyle (Institute for Marine and Antarctic Studies, University of Tasmania)
  • Timothy Emery (Institute for Marine and Antarctic Studies, University of Tasmania)

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

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
Victoria Victoria CIF, OF, PPBF, ITF Environmentally limited Catch, biomass, CPUE
CIF
Corner Inlet Fishery (VIC)
ITF
Inshore Trawl Fishery (VIC)
OF
Ocean Fishery (VIC)
PPBF
Port Phillip Bay Fishery (VIC)
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Stock Structure

Southern Sand Flathead (Platycephalus bassensis) is endemic to Australia and distributed from the central New South Wales coast, around Tasmania to South Australia, and to Bremer Bay in Western Australia1. Southern Sand Flathead inhabit bays, inlets, estuaries and shallow coastal waters to a depth of around 100 m2. There is some evidence of regional subpopulations with differences in physical characteristics, recruitment dynamics and growth rates. For example, Southern Sand Flathead from Port Phillip Bay have slower growth and the asymptotic length is 30 per cent smaller than fish from Bass Strait and 20 per cent smaller than fish from south-east Tasmania3. However, biological stock structure has not been studied in detail and each of the jurisdictions has different management arrangements for Southern Sand Flathead.

Here, assessment of stock status is presented at the jurisdictional level—Western Australia, Victoria, Tasmania and South Australia.

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Stock Status

Victoria

Southern Sand Flathead historically comprised a significant component of the commercial catch in Victoria, with more than 200 tonnes (t) taken annually from Port Phillip Bay for a period, until the 1950s2. This species has also been an important component of the recreational fishery, with an estimated 322 t caught in 2000–013,4. In recent times Southern Sand Flathead has been a commercial bycatch species and the state-wide commercial catch for 2014–15 was less than 5 t, of which 3.6 t came from bays and inlets (mostly Port Phillip Bay)5.

 

Estimates of total biomass for Southern Sand Flathead in Port Phillip Bay, based on fishery-independent trawl surveys, declined by 87 per cent between 2000 and 2010, and the reproductive biomass declined by 60–70 per cent3. No biomass estimates are available since then however, recent commercial catch rates (between 2 and 3 kg per 1000 hook-lifts) remain below the long term average (about 6.5 kg per 1000 hook-lifts), suggesting little recovery since 20105. This decline is due to persistent poor recruitment, which is thought to relate to changing environmental conditions3. The index of recruitment for Port Phillip Bay Southern Sand Flathead (based on fish aged 0+ years) has remained very low since 1998 and appears to be stable below the long-term average. This long-term period of low recruitment will mean that natural recovery of the Port Phillip Bay Southern Sand Flathead biomass is unlikely in the near future5.

 

There is no formal management plan and no limit reference point for Victorian Southern Sand Flathead. Despite the substantial decline in biomass and the significant decline in recruitment for Port Phillip Bay populations3, there is no evidence that these trends are caused by the removal of catch. However, the spawning stock biomass is likely to have declined to the point where average recruitment levels are now significantly reduced.

 

On the basis of low catch (around 5 t per year) and a reduction to the number of licences operating in Port Phillip Bay, the current level of fishing pressure is considered to be relatively low from the commercial sector and is unknown for the recreational sector (the last estimates of exploitation rate were 10 years ago). For many years it was considered that levels of fishing pressure had little influence on Port Phillip Bay Southern Sand Flathead spawning success. This is partly because at least 50 per cent of the population is below the size at which they become vulnerable to fishing6 however, many of these small fish are either immature or have low egg production. A further increase in the size limit to 270 mm in 2009 is expected to decrease the proportion of the population able to be harvested. It is also estimated that most lip-hooked Southern Sand Flathead survive after release, if handled properly3.

 

The most recent estimate of annual exploitation rate of the reproductive biomass in 2006–07 was 44 per cent and there are signs that the age structure of the population is truncating5,6. These signals are of concern, but appear limited to the Port Phillip Bay population. Similar changes have not been found in the Western Port population and little is known about Southern Sand Flathead population status from coastal Victorian waters.

 

On the basis of the evidence provided above, Southern Sand Flathead in Victoria is classified as an environmentally limited stock

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Biology

Southern Sand flathead biology8–10

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Southern Sand Flathead 23 years (both sexes) Males 370 mm TL Females 480 mm TL Males 2.5–3.5 years, 210 mm TL Females 2.6–5.2 years, 235 mm TL
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Distributions

Distribution of reported commercial catch of Southern Sand Flathead

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Tables

Fishing methods
Victoria
Commercial
Line
Mesh Net
Haul Seine
Otter Trawl
Recreational
Diving
Hand Line, Hand Reel or Powered Reels
Management methods
Method Victoria
Commercial
Limited entry
Size limit
Spatial closures
Vessel restrictions
Recreational
Bag limits
Size limit
Active vessels
Victoria
6 in CIF, 9 in ITF, 18 in PPBF
CIF
Corner Inlet Fishery (VIC)
ITF
Inshore Trawl Fishery (VIC)
PPBF
Port Phillip Bay Fishery (VIC)
Catch
Victoria
Commercial 2.33t in CIF, 1.19t in ITF, 975.00kg in PPBF
Indigenous None
Recreational Unknown
CIF
Corner Inlet Fishery (VIC)
ITF
Inshore Trawl Fishery (VIC)
PPBF
Port Phillip Bay Fishery (VIC)

a Victoria – Indigenous In Victoria, regulations for managing recreational fishing are also applied to fishing activities by Indigenous people. Recognised Traditional Owners (groups that hold native title or have agreements under the Traditional Owner Settlement Act 2010 [Vic]) are exempt (subject to conditions) from the requirement to hold a recreational fishing licence, and can apply for permits under the Fisheries Act 1995 (Vic) that authorise customary fishing (for example, different catch and size limits, or equipment). The Indigenous category in Table 3 refers to customary fishing undertaken by recognised Traditional Owners. In 2015, there were no applications for customary fishing permits to access Southern Sand Flathead.
b Tasmania – Recreational (management methods) In Tasmania, a recreational licence is required for fishers using dropline or longline gear, along with nets, such as gillnet or beach seine.c Tasmanian – Indigenous In Tasmania, Indigenous people engaged in aboriginal fishing activities in marine waters are exempt from holding recreational fishing licences, but must comply with all other fisheries rules as if they were licensed. Additionally, recreational bag and possession limits also apply, as do size limits. If using pots, rings, set lines or gillnets, aborigines must obtain a unique identifying code (UIC). The policy document Recognition of Aboriginal Fishing Activities for issuing a Unique Identifying Code (UIC) to a person for Aboriginal Fishing activity explains the steps to take in making an application for a UIC.

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Catch Chart

Commercial catch of Southern Sand Flathead

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Effects of fishing on the marine environment

  • Because most of the catch (95 per cent) is taken by recreational anglers using hand lines, and rods and reels, the effects of fishing on the marine environment are relatively low.
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Environmental effects on Southern Sand Flathead

  • A recent review concluded that declining recruitment from the mid-1990s onwards led to the decline of Southern Sand Flathead stocks in Port Phillip Bay from 2000 onwards. This decline in recruitment coincided with a prolonged drought in Victoria from 1997–2009, characterised by substantially lower rainfall and river flows3. The authors found that recruitment in Port Phillip Bay was significantly correlated with Yarra River flows during November and December, when the majority of Southern Sand Flathead larvae occur in the water column. It is suggested that climatic effects on this stage of the life cycle may be driving variations in recruitment.
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References

  1. 1 Edgar, GJ 2000, Australian marine life: the plants and animals of temperate waters, Reed New Holland Publishers, Frenchs Forest.
  2. 2 Koopman, MT, Morrison, AK and Coutin PC (eds) 2009, Sand Flathead 2000, compiled by the Bays and Inlets Stock and Fishery Assessment Group, Fisheries Victoria internal report 10, Victorian Department of Primary Industries, Queenscliff.
  3. 3 Hirst, A, Rees, C, Hamer, PA, Kemp, JE, and Conron, SD 2014, The decline of Sand Flathead stocks in Port Phillip Bay: magnitude, causes and future prospects, Fisheries Victoria, Queenscliff.
  4. 4 Henry, GW and Lyle, JM 2003, The National Recreational and Indigenous Fishing Survey, Fisheries Research andDevelopment Corporation project 99/158, Australian Government Department of Agriculture, Fisheries and Forestry, Canberra.
  5. 5 Hamer P, Conron S, Hirst A and Kemp J 2016, Sand Flathead Stock Assessment 2015. Fisheries Victoria Science Report Series No. 13, Fisheries Victoria, Queenscliff.
  6. 6 Koopman, M, Morison, AK and Troynikov, V 2004, Population dynamics and assessment of sand and rock flathead in Victorian waters, Fisheries Research and Development Corporation project 2000/120, Primary Industries Research Victoria, Marine and Freshwater Systems, Victorian Department of Primary Industries, Queenscliff.
  7. 7 Emery, T, Lyle, J and Hartmann, K 2016, Tasmanian Scalefish Fishery assessment 2014/15, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart.
  8. 8 Ewing, GP and Lyle, JM 2015, Low-cost monitoring regime to assess relative abundance and population characteristics of sand flathead 2015 update, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart.
  9. 9 Bani, A, and Moltschaniwskyj, NA 2008, Spatio-temporal variability in reproductive ecology of Sand Flathead, Platycephalus bassensis, in three Tasmanian inshore habitats: potential implications for management, Journal of Applied Icthyology, 24(2008): 555–561.
  10. 10 Jordan, AR 1998, The life‐history ecology of Platycephalus bassensis and Nemadactylus macropterus, PhD thesis, University of Tasmania.

Archived reports

Click the links below to view reports from other years for this fish.