Yellowfin Whiting (2020)
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Yellowfin Whiting is found in the coastal waters of south-western Australia. There are two stocks in WA and two in SA. All are assessed as sustainable.
Stock Status Overview
|Western Australia||Southern Western Australia||Sustainable||
|Western Australia||Northern Western Australia||Sustainable||Catch, effort, CPUE, age composition|
Yellowfin Whiting is endemic to south-western Australia, being found in coastal waters around Exmouth in Western Australia to the gulf waters of South Australia [Gomon et al. 2008]. There is some uncertainty about the continuity of the species' distribution through the remote coastal waters between Western Australia and South Australia. Based on this possible discontinuous distribution, there is a possibility of separate stocks in these areas [Steer et al. 2018]. Western Australian populations in northern (Gascoyne Coast Bioregion) and southern (West Coast and South Coast Bioregions) regions also appear to have low connectivity. Adults in northern and southern regions have distinctly different size-at-age due to different growth rates, which suggests low levels of movement among regions [DPIRD unpublished data]. Northern and southern regions are therefore assumed to support separate biological stocks. In South Australia, oceanographic separation of the two gulfs during the spawning season in summer must considerably reduce the opportunity for mixing of eggs and larvae. As such, the populations in the gulfs may constitute separate stocks, but more evidence is required to confirm this.
Here, assessment of stock status is presented at the biological stock level—Northern Western Australia, Southern Western Australia, Spencer Gulf (South Australia) and Gulf St. Vincent (South Australia).
Northern Western Australia
The majority of commercial and recreational catches of Yellowfin Whiting in northern Western Australia occur in Shark Bay. The long-term catch and catch rate trends are relatively stable. Recent commercial catches in Shark Bay have declined due to a reduction in effort, but catch rates in this area have increased, possibly due to strong recruitment after the 2010–11 marine heatwave event, as seen in the Southern Western Australian stock [Jackson et al. 2020]. The age structure of fish in Shark Bay was sampled in 2001–03 and 2014 and was similar in both periods [Brown 2014, Coulson et al. 2005]. Age structure in 2014 was used to estimate fishing mortality and spawning potential ratio (SPR). Estimates of SPR were above the Target Reference Level of 40 per cent. The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Furthermore, the above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.
On the basis of the evidence provided above, the Northern Western Australia biological stock is classified as a sustainable stock.
Southern Western Australia
The previous level 3 assessment was based on age structure data collected in 2015 and 2016. ‘Per recruit’ modelling (SPR) suggested that spawning biomass was above the threshold level (30 per cent).
The current assessment of Yellowfin Whiting taken in Southern Western Australia is primarily based on estimates of biomass and fishing mortality from a data-limited Catch-MSY assessment model, compared periodically to reference levels relating to estimates of Maximum Sustainable Yield (MSY). The estimated biomass expected to achieve MSY (BMSY) is considered as the threshold reference level for the stock, and 50 per cent BMSY is set as the limit reference level. The target level is considered as any stock levels above BMSY.
The estimated fishing mortality experienced by the stock in 2019 was 0.07 year-1, with the 95 per cent CLs ranging from 0.06 to 0.11 year-1. As the upper 95 per cent CL of this performance indicator is well below the level of FMSY (0.3 year-1), the stock is unlikely to deplete to a level at which recruitment could be impaired if the current catch level is maintained.
The point estimate for relative stock biomass in 2019 was high at 0.87 of the unfished level (95 per cent CLs = 0.78–0.95). The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Furthermore, the above evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.
On the basis of the evidence provided above, the Southern Western Australia stock is classified as a sustainable stock.
Yellowfin Whiting biology [Ferguson 2000, Hutchins and Swainston 1986, Hyndes and Potter 1997]
|Species||Longevity / Maximum Size||Maturity (50 per cent)|
|Yellowfin Whiting||Western Australia: 12 years, 420 mm TL South Australia: 11 years, 420 mm TL||Western Australia: 2 years, 180– 200 mm TL South Australia: 2 years, 220–240 mm TL|
Distribution of reported commercial catch of Yellowfin Whiting
|Hand Line, Hand Reel or Powered Reels|
|Hook and Line|
|Rod and reel|
|Recreational||7 t (2017/18)|
Western Australia – Recreational (catch) Recreational catches of Yellowfin Whiting are taken by shore-based fishers. The current recreational catch is unknown due to the absence of any recent surveys of shore-based fishing.
Commercial catch of Yellowfin Whiting - note confidential catch not shown
- Brown, J 2014, Shark Bay Beach Seine and Mesh Net Managed Fishery Stock Status Report December 2014. Unpublished report. Department of Fisheries, Western Australia. 19pp.
- Coulson, PG, Hesp, SA, Potter, IC and Hall, NG 2005, Comparisons between the biology of two co-occurring species of whiting (Sillaginidae) in a large marine embayment. Environmental Biology of Fishes, 73: 125–139.
- Department of Fisheries, September 2017, Addendum to: Johnston, DJ, Smith, KA, Brown, JI, Travaille, KL, Crowe, F, Oliver, RK, Fisher, EA 2015, Western Australian Marine Stewardship Council Report Series No. 3: West Coast Estuarine Managed Fishery (Area 2: Peel-Harvey Estuary) and Peel-Harvey Estuary Blue Swimmer Crab Recreational Fishery. Department of Fisheries, Western Australia. 284pp
- Ferguson, G 2000, Yellowfin whiting (Sillago schomburgkii). South Australian Fisheries Assessment Series 00/10.
- Giri, K and Hall, K 2015, South Australian Recreational Fishing Survey. Fisheries Victoria Internal Report Series No. 62.
- Gomon, M., Bray, D, Kuiter, R. (2008). Fishes of Australia's Southern Coast. New Holland Publishers (Australia) Pty Ltd. 928 pp.
- Hutchins, B and Swainston, R 1986, Sea fishes of southern Australia: complete field guide for anglers and divers. Swainston Publishing, Perth.
- Hyndes, GA and Potter, IC 1997, Age, growth and reproduction of Sillago schomburgkii in south-western Australian, nearshore waters and comparisons of life history styles of a suite of Sillago species. Environmental Biology of Fishes 49: 435–447.
- Jackson, G, Lyttleton, C, Jones, R, Walters, S, and Turner, S 2020, Gascoyne Inner Shark Bay Scalefish Resource Status Report 2019. In: Status Reports of the Fisheries and Aquatic Resources of Western Australia 2018/19: The State of the Fisheries eds. D.J. Gaughan and K. Santoro. Department of Primary Industries and Regional Development, Western Australia.
- Smith, K and Grounds, G, 2020, West Coast Nearshore and Estuarine Finfish Resource Status Report 2019. In: Status Reports of the Fisheries and Aquatic Resources of Western Australia 2018/19: The State of the Fisheries eds. D.J. Gaughan and K. Santoro. Department of Primary Industries and Regional Development, Western Australia.
- Steer, MA, Fowler, AJ, Rogers, PJ, Bailleul, F, Earl, J, Matthews, D, Drew M, Tsolos, A 2020, Assessment of the South Australian Marine Scalefish Fishery in 2018. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2017/000427-3. SARDI Research Report Series No. 1049. 213 pp.