Biological Time Series - Marine Animals


Continental-scale shark migrations


Michelle Heupel1

Vic Peddemors2

Mario Espinoza1

Amy Smoothey2

Colin Simpfendorfer3

1 Australian Institute of Marine Science, Townsville, QLD, Australia
2 Fisheries New South Wales, NSW Department of Primary Industries, Sydney Institute of Marine Science, Mosman, NSW, Australia
3 Centre for Sustainable Tropical Fisheries and Aquaculture, College of Marine and Environmental Sciences, James Cook University, Townsville, QLD, Australia

Key Information

Understanding movement and connectivity of populations is critical to management and conservation efforts. Through the IMOS Animal Tracking Facility the movements of bull sharks were tracked along the east coast of Australia between Sydney Harbour and the central Great Barrier Reef (GBR). This continental-scale tracking data identified previously unknown population connections with large numbers of bull sharks making return trips between Sydney and the GBR and revealing the importance of both of these regions for this species.


Sydney Harbour, southern Great Barrier Reef, Bull Sharks,

Continental-scale shark migrations

Movement and connectivity of marine populations is increasingly important as human use and environmental change alter ocean ecosystems. Identifying movement patterns is particularly important for species that move long distances and thus link ecosystems (e.g., coastal and offshore regions). The ability to move across state or national boundaries is also a topic of concern for management and conservation efforts. Large predators are key components of ecosystems due to their ability to directly (through predation) and indirectly (through fear affecting prey movements and distribution) affect other species. Here we investigate the capacity for large predators to connect habitats and affect an array of communities. In addition, understanding how they move, connect habitats and interact with other species can help define their role in ecosystems, which can help identify potential consequences of any population declines.

Movements of bull sharks were examined using acoustic telemetry receiver arrays along the east coast of Australia spanning from Sydney Harbour to the central Great Barrier Reef (GBR). Acoustic tracking data were obtained from the Integrated Marine Observing System (IMOS) Animal Tracking Facility and examined to define the extent and timing of movement of tagged sharks (Australian Ocean Data Network dataset: “IMOS - Animal Tracking Facility - Acoustic Tracking - Quality Controlled Detections (2007 -2017)”). A total of 114 bull sharks were fitted with acoustic transmitters – 75 in NSW and 39 in QLD (Figure 1). Straight line distances between detection locations were determined to approximate movement along the coast. To examine the level of connectivity among acoustic receiver arrays, a chord diagram was compiled to define incoming and outgoing movements of individuals.

Approximately half (n = 36) of the bull sharks tagged in NSW moved north into tropical regions. Seventeen individuals moved north and did not return to NSW. Both males and females were recorded undertaking long-range movements. Straight line distances were estimated at 60 – 1770 km one way (Figure 2). Several individuals were recorded making multiple, repeat movements between NSW and QLD, in some cases as many as five subsequent trips. The majority of repeat movements were completed by female sharks. Larger individuals were more likely to move than smaller individuals, suggesting differences in behaviour by life stage. By contrast, only one shark tagged in QLD moved into NSW, but 25% of QLD tagged sharks moved to southern reefs or inshore habitats. Some of the individuals tagged in QLD remained resident in the area throughout the study period and 50% of individuals that left their tagging area (central GBR) returned to the area. Connectivity analysis reflected the high degree of movement among locations and the scale of movement exhibited by this species (Figure 3).

These results reveal complex linkages along the east coast of Australia, which suggest a tropical reef-based population comprised of individuals that migrate to multiple regions. Continental-scale acoustic telemetry systems can help define long-range movements and connectivity of broadly moving species such as large sharks. This analysis also revealed the importance of the GBR for adult bull sharks, which was previously unknown. The scale of movement and capacity to connect coastal temperate habitat to tropical reef habitat through movement suggest bull sharks could play a key role in ecosystem functions and energy linkage along the east coast of Australia.

The previously unknown importance of bull sharks in large marine ecosystems has been elucidated through data obtained via the IMOS Animal Tracking Facility. The analysis of bull shark movements highlights the complex challenges faced by managers when species move broadly and cross jurisdictional boundaries. Movement across state boundaries emphasises the need for cooperation among management agencies to ensure sharks receive adequate protection during their migrations. These data underscore the potential for sharks to move outside Australian waters and that this should be considered in international management agreements. This study reveals the capacity of acoustic telemetry networks to obtain valuable movement data can guide effective management and conservation policies for highly mobile species.

Heupel, M.R., Simpfendorfer, C.A., Espinoza, M., Smoothey, A.F., Tobin, A., Peddemors, V. 2015. Conservation challenges of sharks with continental scale migrations. Frontiers in Marine Science. doi: 10.3389/fmars.2015.00012

Figure 1

Measuring and tagging a captured bull shark in QLD.

Figure 2

Straight line movements of an individual released in (A) NSW and (B) QLD based on detections on acoustic arrays beyond their capture location.

Figure 3

Map indicating the location of acoustic receiver arrays along the east coast of Australia and associated connectivity plot (chord diagram), indicating movement of individuals between receiver arrays.

Download this Time Series Report

Citing this report: 

Heupel M, Peddemors V, Espinoza M, Smoothey A, Simpfendorfer (2020). Continental-scale shark migrations. In Richardson A.J, Eriksen R, Moltmann T, Hodgson-Johnston I, Wallis J.R. (Eds). State and Trends of Australia’s Ocean Report. doi: 10.26198/5e16b18449e8c

doi: 10.26198/5e16b18449e8c

Access the Data

Access the data that contributes to this time-series by clicking the icons below

08a. Acoustic telemetry-02

Acoustic Telemetry

Citing the Report

Richardson A.J, Eriksen R, Moltmann T, Hodgson-Johnston I, Wallis J.R. (2020). State and Trends of Australia’s Ocean Report, Integrated Marine Observing System (IMOS).


The State and Trends of Australia's Ocean Report was supported by IMOS. IMOS gratefully acknowledges the additional support provided by the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

The State and Trends of Australia's Ocean website is maintained by IMOS.



Australia’s Integrated Marine Observing System (IMOS) is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). It is operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent.


You accept all risks and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this site and any information or material available from it. While the Integrated Marine Observing System (IMOS) has taken reasonable steps to ensure that the information on this website and related publication is correct, it provides no warranty or guarantee that information provided by the authors is accurate, complete or up-to-date. IMOS does not accept any responsibility or liability for any actions taken as a result of, or in reliance on, information on its website or publication. Users should check with the originating authors to confirm the accuracy of the information before taking any action in reliance on that information.

If you believe any information on this website or in the related publication is inaccurate, out of date or misleading, please bring it to our attention by contacting the authors directly or emailing us at

Images and Information:

All information on this website remains the property of those who authored it. All images on this website are licensed through Adobe Stock, Shutterstock, or have permission from the original owner.