Shark biology breakthrough: Study tracks tiger sharks to Maui mating hub

(Press-News.org) Researchers from the University of Hawaiʻi at Mānoa's Hawaiʻi Institute of Marine Biology (HIMB) Shark Lab have solved a long-standing global mystery in shark biology: the location and nature of tiger shark mating. A new study, based on six years of acoustic tracking data, provides the first concrete evidence of a potential seasonal mating aggregation site for tiger sharks, located off Olowalu, Maui.

This discovery challenges the conventional understanding of tiger sharks as purely solitary animals, revealing a predictable seasonal convergence of mature males and females that coincides with the humpback whale calving season in Hawaiʻi.

Solving the Mating Mystery For years, it was unclear how tiger sharks, which are typically solitary wanderers, came together to reproduce, or if mating was simply a result of random encounters. The new findings strongly suggest an annual, predictable gathering site.

“Tiger sharks typically roam widely in what can seem like random patterns, so finding such a strong and consistent seasonal trend in their movements around Maui was unexpected,” explains Paige Wernli, lead author of the study and a graduate student in the HIMB Shark Lab. “We were surprised to see that these sharks are so predictably present at one location and time of year.”

The long-term tracking data revealed a strong, predictable seasonal presence and high spatiotemporal overlap of both mature male and female sharks at Olowalu, with both sexes exhibiting physical signs of mating activity.

“To our knowledge, no group mating site for tiger sharks has ever been identified. This paper adds an important piece to the puzzle of tiger shark reproduction,” shares Carl Meyer, co-author of the paper and Principal Investigator of the HIMB Shark Lab.

Dual Motivations: Mating and Foraging While the presence of mature sharks of both sexes strongly 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 unique ecological overlap indicates that the sharks may be positioning themselves to take advantage of foraging opportunities, such as vulnerable calves or placental falls.

“Mating and foraging on humpback whales may not be mutually exclusive,” explains Wernli, “and both could influence tiger shark movement patterns in Hawaiʻi.”

The researchers noted that these gatherings are not dense but rather diffuse, spanning multiple months and several kilometers. 

“This study expands our knowledge of tiger shark mating and challenges our conventional understanding of the term ‘gathering,’” adds Meyer. “Together, the results suggest that both reproduction and food availability play key roles in shaping tiger shark movements in Hawaiʻi.”

Tenacity and Technology: Six Years of Tracking The six-year study required the research team to safely catch and implant acoustic transmitters in large sharks, then maintain a vast network of underwater listening stations across the Main Hawaiian Islands.

“Tracking wild sharks in the open ocean is inherently challenging,” shares Wernli. “Even with all that effort, wide-ranging sharks don’t always show obvious patterns, so a lot of patience and persistence is required to get meaningful results.”

Moving forward, the research team plans to equip tiger sharks with camera accelerometer tag packages to directly document mating behavior and shark-whale interactions, providing a real "shark's eye view" into their daily lives.

This work was funded by the Hawaiʻi Department of Land and Natural Resources (DLNR) and the Pacific Islands Ocean Observing System (PacIOOS).

END