*

King Threadfin in the WA and NT jurisdictions, as well as the QLD east coast management unit are classified as sustainable. In contrast, the Gulf of Carpentaria biological stock is classified as a depleting stock.

King Threadfin have numerous populations across northern Australia that are separated by 10–100s km or by large, coastal geographical features [Moore et al. 2011, Welch et al. 2010]. With the exception of the Gulf of Carpentaria, there is a lack of information on the degree to which this separation indicates separate biological stocks, and on boundaries between possible stocks.

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

Western Australia

King Threadfin is landed in the Kimberley Gillnet and Barramundi Managed Fishery (KGBMF) of Western Australia. The catch of King Threadfin in the KGBMF has been low and stable for the past six years (2014–19), ranging from 18–25 tonnes (t), with a mean annual catch of 21.0 t. The recent catches from 2014–2019 are well below the average of 81.8 t for the 10-year period from 2004–13. This is due to low effort levels in the fishery [Newman et al. 2020] following the removal of two fishing licences from the Broome coast area. The Broome coast area has been closed to commercial fishing since late 2013. This commercial closure in the principal landing area for King Threadfin catches, in association with their rapid growth rates, is likely to have substantially increased the spawning stock biomass of this species. King Threadfin are landed by recreational fishers (estimated catch 3 t), and also by charter fishers but only in negligible quantities. The above evidence indicates the biomass of this stock is unlikely to be depleted and that the recruitment is unlikely to be impaired. Furthermore, the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, King Threadfin in Western Australia is classified as a sustainable stock.

King Threadfin biology [Welch et al. 2010]

Western Australia – Recreational (Catch) Boat-based recreational catch is from 1 September 2017–31 August 2018. These data are derived from those reported in Ryan et al. [2019]. It is important to note that catches of King Threadfin are underestimated as shore-based fishers were out of scope of the survey. Shore based catches of King Threadfin are not known.

Western Australia – Recreational (management methods) A Recreational Fishing from Boat Licence is required for the use of a powered boat to fish or to transport catch or fishing gear to or from a land-based fishing location.

Western Australia – Indigenous (management methods) Subject to application of 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.

Queensland – Indigenous (management methods) for more information see https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

Northern Territory – Charter (management methods) In the Northern Territory, charter operators are regulated through the same management methods as the recreational sector but are subject to additional limits on license and passenger numbers.

Northern Territory – Indigenous (management methods) The Fisheries Act 1988 (NT), specifies that “…without derogating from any other law in force in the Territory, nothing in a provision of this Act or an instrument of a judicial or administrative character made under it limits the right of Aboriginals who have traditionally used the resources of an area of land or water in a traditional manner from continuing to use those resources in that area in that manner”.

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