Do some tiger sharks prefer beaches? Insights from a broad-scale tracking program

Abstract

Human coastal populations and water-based recreation are growing, increasing potential for interactions with sharks in coastal waters near popular beaches. However, lethal means of mitigating shark bite risks may have ecological effects, while non-lethal relocation of sharks could result in recurrent risks to beachgoers. Tiger sharks (Galeocerdo cuvier) are one of three species involved in most unprovoked shark bites globally. Under the Queensland Shark Control Program, tiger sharks caught on drumlines and catch alert drumlines at beaches in the Great Barrier Reef Marine Park are tagged and relocated away from the beach. Using the IMOS acoustic tracking network of eastern Australia, we compared movements of 51 tiger sharks relocated from beaches with 82 tagged at other locations in the marine park over more than two years. We discuss whether relocated tiger sharks are more likely to visit beaches than conspecifics from locations further offshore. We also compare the broad-scale movement ecology of both groups using network analyses and assess trends in visitation and residency at beaches among sex and maturity classes. Insights from this study will help assess the risks and benefits of relocating tiger sharks away from popular beaches.