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Common Blacktip Sharks are found worldwide in tropical and warm temperate waters. Three biological stocks—East Coast, Gulf of Carpentaria and North and West Coast—have been identified for Australia. The East Coast and North and West Coast stocks are sustainable, while the Gulf of Carpentaria stock is undefined. Previous editions of the SAFS reports have combined Australian Blacktip Shark, Common Blacktip Shark and Spot-Tail Shark, but all three are now reported at the species level.

Photo: Michael Usher, Department of Primary Industry and Resources, Northern Territory

Common Blacktip Shark have a circumglobal distribution in tropical and warm temperate waters. In Australian waters, genetic studies have identified three biological stocks of Common Blacktip Shark, a western stock extending from the western Northern Territory into northern Western Australia, a Gulf of Carpentaria (GoC) stock and an east coast stock in Queensland and New South Wales [Ovenden et al. 2007]. The stock boundary between the North and West Coast, and Gulf of Carpentaria biological stocks is uncertain. 

Common Blacktip Shark are similar in appearance to the Australian Blacktip Shark (C. tilstoni). Previously taxonomical differentiation of these species was only possible by genetic analyses, precaudal vertebral counts or, in certain size classes, differences in size of maturity [Harry 2011]. A new identification technique, utilising body measurements and pelvic fin colouration, has been developed and may assist in distinguishing between these two species. However, accurate field identification remains difficult and is not practical during commercial fishing operations [Johnson et al. 2017]. Hybridisation between the species has also been recorded, though its implications for fisheries assessment and management remain poorly understood [Harry et al. 2012, Johnson 2017, Morgan et al. 2011]. Consequently, Common Blacktip and Australian Blacktip sharks are often reported as a species complex in commercial logbooks.  For the purpose of these assessments a portion of the combined Blacktip Shark catch for each jurisdiction has been attributed to Common Blacktip Shark using relative abundance ratios determined from on board observer programs and published research [Johnson 2017, Ovenden 2007].

Here, assessment of stock status for Common Blacktip Shark is presented at the biological stock level—North and West Coast, Gulf of Carpentaria, and East Coast.

North and West Coast

The North and West Coast biological stock straddles two jurisdictions: The Northern Territory, west of the Wessel Islands–Western Australian border; and Western Australia.

Changing operational practices in the NT Offshore Net and Line Fishery have greatly reduced the take of Common Blacktip Shark in the Northern Territory. There has been little to no shark-targeted fishing occurring in the Northern Territory since 2012 as a result of declining shark fin prices and increasing value of Grey Mackerel (Scomberomorus semifasciatus), which is currently the main target species of this fishery. In this circumstance, the declining catches have provided opportunity for the population of Common Blacktip Shark to recover.

Although there is uncertainty regarding species composition and the magnitude of historical catches of Blacktip Sharks from Western Australia, harvests of Common Blacktip Shark in this jurisdiction have been negligible since April 2009 [Molony et al. 2013], allowing the biomass to increase.

The most recent stock assessment, using data up to 2019, was undertaken for the North and West Coast biological stock of Common Blacktip Shark utilising a catch-MSY model. The results estimated that the biomass was approximately 53 per cent of the unfished biomass and that harvests were below that required to achieve maximum sustainable yield [Usher et al. 2020b]. 

On the basis of the evidence provided above, the North and West Coast biological stock of Common Blacktip Shark is classified as a sustainable stock.

Blacktip Sharks biology [Harry, 2011, Harry et al. 2019, Last and Stevens 2009]

Distribution of reported commercial catch of Common Blacktip Sharks

Western Australia – Recreational (Management methods) A recreational fishing from boat licence is required for recreational fishing from a powered vessel in Western Australia.

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

New South Wales – Indigenous (Management Methods) https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing

New South Wales commercial fisheries with less than seven active fishers are not presented due to the Privacy Act.

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”.

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.

Commercial catch of Common Blacktip Sharks - note confidential catch not shown

1. Harry, AV (2011) Life histories of commercially important tropical sharks from the Great Barrier Reef World Heritage Area, PhD thesis, James Cook University, Townsville
2. Harry, AV, Butcher, PA, Macbeth, WG, Morgan, JAT, Taylor, SM and Geraghty, PT (2019) Life history of the Common Blacktip Shark, Carcharhinus limbatus, from central eastern Australia and comparative demography of a cryptic shark complex. Marine and Freshwater Research, 70, 6, 834-848
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12. QFish, Department of Agriculture and Fisheries, www.qfish.gov.au
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15. Usher, M, Saunders, T and Braccini M (2020b) Stock Status Summary - 2020 Common Blacktip Shark (Carcharhinus limbatus) North and West Coast stock Catch-MSY. Unpublished Fishery Report
16. Usher, M, Saunders, T and Roelofs, A (2020a) Stock Status Summary - 2020 Common Blacktip Shark (Carcharhinus limbatus) East Coast stock Catch-MSY. Unpublished Fishery Report