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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: Department of Industry, Tourism and Trade, 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 and, while a new investigation is helping to understand the prevalence and dynamics of this phenomenon [Queensland Department of Agriculture and Fisheries 2021], the current knowledge regarding its implications for fisheries assessment and management is limited [Harry et al. 2012; Johnson et al. 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 et al. 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.

East Coast

In Queensland, the last stock assessment for the Common Blacktip Shark was completed in 2015 and was based on data up to and including 2013 [Leigh 2015]. This assessment produced Maximum Sustainable Yield (MSY) estimates for the Common Blacktip Shark on the Queensland east coast ranging from 237 t to 907 t. The lower bound of the MSY estimate range is highly conservative and was included in the assessment in response to concerns surrounding the quantity and quality of the available data on shark harvests [Leigh 2015].

Harvest for the Common Blacktip Shark peaked between 2003–04 and 2007–08 with an average annual harvest of 111 t. In 2021–22, the annual commercial harvest was 24 t, which was below the 10-year average of 35 t and well below the most conservative MSY estimate of 237 t [Leigh 2015]. This reflects a sustained long-term drop in harvest for the Common Blacktip Shark. 

Observed declines in the annual harvest are attributed to poor market demand, declining effort and management reforms targeted at the commercial net fishery rather than declining biomass. The most significant reforms were implemented in 2009 and included the introduction of a combined 600 t Total Allowable Commercial Catch (TACC) limit for retained sharks and rays. In 2021, this limit was reduced to 400 t (not including Hammerhead Sharks) as part of a broader reform program for the East Coast Inshore Fishery (ECIF). These reforms included a transition in the ECIF to regional management, and a fishery-specific harvest strategy. The harvest strategy includes reference points, trigger limits and other measures to guide the long-term management of sharks harvested on the Queensland east coast [Queensland Department of Agriculture and Fisheries 2020]. 

Outside of the commercial fishing sector, the catch of Common Blacktip Sharks in Queensland waters is low to negligible. The Queensland Shark Control Program typically reports the capture of less than five individuals per year [Queensland Government 2023]. No recreational data is available for this species [Teixeira et al. 2021]. However, recreational harvest is limited by a one shark in possession limit and a maximum legal size limit of 1.5 m total length. Commercial catch records for the New South Wales Ocean Trap and Line Fishery indicate that the annual reported commercial catch of Blacktip Sharks (comprising mostly Common Blacktip Shark) from New South Wales waters ranged from 13–66 t during the 10 year period spanning financial years from 1998–99 to 2007–08 [Macbeth et al. 2009]. However, significant use of catch reporting categories 'Unspecified Sharks' (5–204 t) and 'Unspecified Whaler Sharks' (7–26 t) during that period suggest that these historical quantities are most probably underestimates. Since management intervention in this fishery in 2009, the tonnage of Blacktip Sharks caught has dropped substantially and the reliability of species-specific catch reporting has improved considerably [Macbeth et al. 2018]. A total of 24.1 t of Blacktip Sharks (comprising mostly C. limbatus) was landed in New South Wales during the 2022 fiscal year The catch of Blacktip Sharks in the New South Wales Shark Meshing Program is negligible, at less than 1 t per year [Dalton et al. 2023]. Collectively, these figures indicate that the overall catch of this species in New South Wales waters is minimal in terms of impacting the East Coast stock. 

The most recent assessment, using data up to 2019, was undertaken for the East Coast biological stock of Common Blacktip Shark utilising a catch Maximum Sustainable Yield (catch-MSY) model. The assessment estimated that the harvest rate for Common Blacktip Shark was below that required to reach MSY and that the biomass in 2019 was 68% of the unfished biomass [Usher et al. 2020a]. Overall, the information provided above indicates that the biomass of the stock is not considered to be depleted and that 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, the East Coast biological stock of Common Blacktip Shark is classified as a sustainable stock. 

Gulf of Carpentaria

The Gulf of Carpentaria biological stock straddles two jurisdictions: The Northern Territory, east of the Wessel Islands-Queensland border and Queensland, west of Torres Straight Islands to the Northern Territory border. In this stock, most Common Blacktip Sharks are reported by Queensland Fisheries (Queensland 18 t; Northern Territory 1.3 t). However, there are limitations associated with the species identifications which impact the quantity and reliability of available catch data [Leigh 2015]. As a result of these deficiencies, Maximum Sustainable Yield (MSY) could not be estimated for the species in the Gulf of Carpentaria [Leigh 2015] and estimates of harvest in Queensland are currently Null as catch is attributed to C. tilstoni following Leigh [2015] and Ovenden et al [2007]. 

On the basis of the evidence provided above, the Gulf of Carpentaria biological stock of Common Blacktip Shark is classified as an undefined stock.

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

Distribution of reported commercial catch of Common Blacktip Shark

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 informationsee https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

Queensland – Commercial (Catch). Queensland commercial and charter data have been sourced from the commercial fisheries logbook program. Due to low confidence in species-specific reporting caused by challenges in distinguishing between C. limbatus and C. tilstoni, catch for this species has been derived by combining harvest across the multiple blacktip shark reporting categories and applying a latitudinal split following Leigh [2015] and Ovenden et al. [2007]. Further information available through the Queensland Fisheries Summary Report https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/data/queensland-fisheries-summary-report

Queensland – Recreational Fishing (Catch). Data with high uncertainty (Residual Error >50 %) has been excluded and listed as unknown. More information available at: https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/monitoring-reporting/statewide-recreational-fishing-surveys  

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

Queensland – Commercial (Management Methods). Harvest strategies are available at: https://www.daf.qld.gov.au/business-priorities/fisheries/sustainable/harvest-strategy  

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

Northern Territory - Indigenous (management methods). The Fisheries Act 1988 (NT), specifies that: “Unless expressly provided otherwise, nothing in this Act derogates or limits the right of Aboriginal people who have traditionally used the resources of an area of land or water in a traditional manner to continue 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 Shark - note confidential catch not shown

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