Animal Tracking: Are Tiger Sharks Beachgoers?
Featured Image Caption: An adult tiger shark swimming in the ocean. (Image Source: ‘Tiger Shark’ by Etienne Guitton, CC-BY-NC 4.0, via iNaturalist)
Source Article: McMillan, M., Barnett, A., Bierwagen, S., Scott-Holland, T., Udyawer, V., Campbell, M., Fitzpatrick, R., Lubitz, N., Miller, I., & Currey-Randall, L. (2025, October 24). Do some tiger sharks prefer beaches? insights for shark management from a broad-scale comparative tracking study – sciencedirect. ScienceDirect. https://www.sciencedirect.com/science/article/pii/S0964569125004260
Trail and Error
As coastal populations continue to grow, human and shark interactions increase near beach environments. The spatial overlap between these interactions conflicts with human user safety and the ecological importance of shark populations. In fact, shark control programs have been adopted in countries such as Brazil, South Africa, and the U.S. and have been documented to use fatal practices to decrease dangerous shark encounters near beaches, including the tiger shark. The tiger shark (Galeocerdo cuvier) is one of three sharks responsible for unwarranted shark bites on humans.
Alternative approaches, such as the Queensland Shark Control Program (QSCP), an Australian program established in 1962 approaches shark bite mitigation mostly through non-lethal methods. The program acts across 86 beaches along Queensland’s coast, tagging potentially dangerous sharks and monitoring their locations. To measure the success of relocation methods, QSCP utilized drumlines, an aquatic trapping mechanism, to catch and tag tiger sharks after relocation. To increase the success in tracking, the QSCP coordinated with the Integrated Marine Observing System (IMOS) for a variety of results. Acoustic receivers were utilized on over 2100 kilometers of coastline to detect tiger shark habitat range and increase success in capturing accurate tracks at monitored beaches. In this study, tagged sharks were used to assess shark movements and their behavior regarding beach visitation.
A New Home?
Tagged sharks were equipped with an Innovasea V16-6X acoustic transmitter at the base of the dorsal fin. From September 2020 to December 2022, 197 tiger sharks were tagged with external and internal acoustic transmitters. After being tagged, QSCP tiger sharks were released approximately 1 kilometer from beaches, while IMOS were re-located between 24-135 kilometers away from beaches. Acoustic receivers were then deployed between the Great Barrier Reef system to New South Wales to capture shark movements across the network.
During the study period, 133 tiger sharks were used for statistical analysis. 51 out of 133 were detected by the IMOS acoustic receiver throughout Queensland, New South Wales, and Norfolk Island, with 82 sharks detected in other parts of the marine park. After relocation, sharks returned to beaches after a median period of 93 days, with some returning more frequently than others. Tiger shark beach visits were concise (<30 min), with visitations peaking from 10:00pm to 12:00am (Figure 1).
Sharks were grouped by sex/maturity class, including immature and mature sexes respectively. During analyses, immature females were the most detected but the least resident at beaches, opposite to the tendencies shown by more mature female tiger sharks. However, residency at beaches were low overall (>20%). Furthermore, sharks tagged away from beaches moved from tagging sites to adjacent coastal areas and reef sites. Researchers noted that the monitored beaches were most likely to be visited by relocated sharks, with almost 50% of sharks revisiting after relocation.
Moving Across the Waters
The researchers reiterate the statement that beaches with low-use areas have low residency, meaning beachgoers are at low risk. Tiger shark visits mostly occurred at night, further limiting harmful human and shark interactions. The specimens tagged further offshore visited beaches far less than those tagged onshore. Relocated beach sharks were most likely to visit due to natural behavior patterns, such as partial migrations and foraging strategies. Tiger shark foraging activity is a driver in behavioral characteristics, which explains why some sharks visited mainland beaches more than others.
In regard to foraging behavior, lighting conditions and hunting adaptations may also influence why tiger sharks tend to visit beaches. Shallow areas such as beaches may enhance foraging success, especially during night where there is limited light available. Although tiger sharks prefer surface waters for hunting, low-light conditions may increase hunting success due to low-visibility. Also, the sex/maturity categories may suggest that female tiger sharks may use inshore nurseries, which is a common behavior of other shark species.
Managing Tiger Shark Populations
The study suggests that beach-relocated tiger sharks are more likely to return to mainland beaches, but after an average timespan of three months. This indicates that the likelihood of risks are significantly reduced to humans, with lower shark bite risks overall. Due to most visitations occurring at night, risks are further limited. In order to decrease shark outlook negativity, the QSCP has also started an educational program to promote important information regarding sharks, including shark bite mitigation and peak shark time activities.
Tracking of sharks helps understand their behaviors better and thus mitigate possible risks. The relocation methods used by the QSCP also assists in promoting non-lethal efforts in population management efforts. Although sharks are overall looked at negatively, they provide important ecological benefits as an apex predator by regulating the marine food web and controlling prey populations. In light of future conservation efforts, it is anticipated that wildlife and environmental management looks towards more peaceful solutions for shark management.
