Broad-scale coastal movements of white sharks off Western Australia described by passive acoustic telemetry data

Abstract

Movements of 89 acoustically tagged subadult and adult white sharks (Carcharodon carcharias) were monitored off the south and west coasts of Western Australia (WA) between December 2008 and May 2016 by a network of up to 343 passive acoustic receivers. In all, 290 inter-regional movements, totalling 185092km were recorded for 73 of these sharks. Estimated rates of movement in excess of 3kmh–1 (mean 1.7kmh–1; maximum 5.6kmh–1) were common, even over distances of thousands of kilometres. Detections indicated that white sharks may be present off most of the south and lower west coasts of WA throughout the year, although they are more likely to be encountered during spring and early summer and are least likely to be present during late summer and autumn. There was limited evidence of predictable return behaviour, seasonal movement patterns or coordination of the direction and timing of individual shark’s movements. Nevertheless, the data suggest that further analyses of movements in relation to ecological factors may be useful predictors of shark activity at local scales. It is hoped that these data may be useful for informing public safety initiatives aimed at mitigating the risks associated with human encounters with white sharks off the WA coast.

Broad-scale movements of juvenile white sharks Carcharodon carcharias in eastern Australia from acoustic and satellite telemetry

“…White sharks in the Australasian region differ genetically from other populations (Pardini et al 2000), and data suggest there are 2 populations in southern Australia separated east and west by Bass Strait (Blower et al 2012). This Australasian population structure is further supported by acoustic and satellite tagging studies (Bruce & Bradford 2012, McAuley et al 2017.…”

“…These rates are consistent with other studies. McAuley et al (2017) estimated that a 1.8 m (TL) male white shark travelled at a rate of 5.6 km h −1 covering 193 km in only 35 h. A further 25 sharks were estimated to have rates of movement of over 3 km h −1 for distances between 103 and 3362 km. Domeier & Nasby-Lucas (2008) showed that adult white sharks travelled along a migration corridor offshore into the eastern Pacific at speeds of approximately 3.2 km h −1 , suggesting that rapid, direct, longdistance movements are relatively common for this species.…”

“…Apex predators can potentially have a profound influence on their surrounding ecosystem (Ruppert et al 2013). Understanding the extent of their movements and habitat use will assist with conserving such species, managing marine communities and, in the case of white sharks, the prospect of minimising threats to human safety (McAuley et al 2017). Using a combination of acoustic telemetry and satellite tracking data, this project documents the large-scale movements of juveniles over a 7 yr period along the east coast of Australia.…”

Where technology meets ecology: acoustic telemetry in contemporary Australian aquatic research and management

“…This technology has since seen widespread application in the real-time detection of potentially dangerous megafauna along the Australian coast, principally to help manage the risk of shark attacks along popular beaches. McAuley et al (2017) provide a recent application of this technology to understand ecological drivers of white shark (Carcharodon carcharias) movements in a public safety context. This synthesis found little evidence of predictable movement patterns across broad scales, either in the location of animals, the direction of their migration or the timing of their movements; however, the data did suggest some predictable patterns in movement at smaller, regional scales (McAuley et al 2017).…”

“…McAuley et al (2017) provide a recent application of this technology to understand ecological drivers of white shark (Carcharodon carcharias) movements in a public safety context. This synthesis found little evidence of predictable movement patterns across broad scales, either in the location of animals, the direction of their migration or the timing of their movements; however, the data did suggest some predictable patterns in movement at smaller, regional scales (McAuley et al 2017). The integration of this technology with both the national network and use of smartphone apps (see http://www.dpi.nsw.…”