Telemetry reveals potential mating aggregation behavior of tiger sharks (Galeocerdo cuvier) in Hawai'i.

Tiger sharks (Galeocerdo cuvier) are typically solitary marine predators that are rarely observed forming aggregations. We analyzed long-term acoustic telemetry data from the Hawaiian Archipelago that indicate that there are seasonal partial migrations within the population. We investigated whether these migrations are driven primarily by mating or foraging behaviors. Mature tiger sharks tagged around O 'ahu migrated seasonally to Maui, with timing aligned with the known mating season in Hawai 'i. In contrast, sharks tagged around Maui displayed year-round residency (no seasonal departures). Seasonal philopatry was most pronounced at Olowalu, Maui. At this site, we observed a high spatiotemporal overlap between mature males and females and physical signs of mating activity for both sexes, which suggested a mating aggregation. Shark abundance at Olowalu peaked approximately one month prior to the peak presence of adult humpback whales (Megaptera novaeangliae). Whale calf abundance was moderately correlated with shark detection rates, suggesting that foraging opportunities might also influence the timing of shark aggregations. These aggregations appear diffuse rather than dense, extending over several kilometers and persisting for several weeks. Our findings provide the first evidence of potential seasonal mating aggregations in tiger sharks, a behavior previously undocumented for this typically solitary species.