Researchers from the University of Hawaiʻi at Mānoa's Hawaiʻi Institute of Marine Biology (HIMB) Shark Lab have identified a potential seasonal mating aggregation site for tiger sharks. This discovery, detailed in a new study based on six years of acoustic tracking data, is located off Olowalu, Maui.
The findings challenge the previous understanding of tiger sharks as purely solitary animals. The research indicates a predictable seasonal convergence of mature males and females. Long-term tracking data revealed a consistent seasonal presence and high spatiotemporal overlap of both mature male and female sharks at Olowalu, with both sexes exhibiting physical signs consistent with mating activity.
While the presence of mature sharks of both sexes suggests a mating aggregation, the timing of their convergence also aligns with the arrival of humpback whale mothers and newborn calves in the area. This ecological overlap suggests that the sharks may be positioning themselves to take advantage of foraging opportunities, such as vulnerable calves or placental falls. The researchers noted that these gatherings are diffuse, spanning multiple months and several kilometers.
The six-year study involved safely catching and implanting acoustic transmitters in large sharks, then maintaining a network of underwater listening stations across the Main Hawaiian Islands.
Moving forward, the research team plans to equip tiger sharks with camera accelerometer tag packages. This aims to directly document mating behavior and shark-whale interactions. The Hawaiʻi Department of Land and Natural Resources (DLNR) and the Pacific Islands Ocean Observing System (PacIOOS) funded this work.