Long-term movement patterns of tiger sharks Galeocerdo cuvier in Hawaii

Abstract

Little is known about the long-term movement patterns of most marine apex predators. A network of acoustic receivers was used to quantify the long-term movements of transmitterequipped tiger sharks Galeocerdo cuvier Péron & Lesueur, 1822 in the Main Hawaiian Islands. Tiger sharks were wide-ranging, swam between islands and patrolled up to 109 km of contiguous coastline. Visits to specific acoustic receiver sites were typically brief (mean duration 3.3 min), unpredictable and interspersed by absences of weeks, months or years. This pattern may be an optimal foraging strategy for capturing risk-averse prey. Tiger sharks may have to move on soon after arriving in an area because the element of surprise is quickly lost and potential prey become wary and difficult to catch. Juvenile tiger sharks were significantly wider-ranging and less frequently detected than mature females. Juveniles may be avoiding predation by larger individuals, or exploring to find suitable home ranges. Tiger sharks may also switch movement patterns and foraging strategies to take advantage of different prey types, restricting their movements to exploit seasonally abundant and naïve prey. Further empirical studies are required to directly link movement patterns with foraging. © 2009 Inter-Research.