BACKGROUND

In November 2018 we traveled to the remote Tuamotus in search of tiger shark population hotspots. It is believed that the large female tiger sharks migrate between the main island of Tahiti and the islands of the Tuamotus as a part of reproductive pattern. We connected with local fishermen, who are often the most educated on shark movement patterns and habitat spatial array, in order to locate a hotspot where tiger sharks may congregate outside of the infamous La Vallee Blanche of Papeete.

“Tiger lagoon”

During our search we were led by fishermen to a protected lagoon in which tiger sharks were congregating naturally in a larger than average number socially as well as exhibiting a longer than average residency within the area. The tiger sharks observed primarily range between juvenile to sub-adult with an occasional fully mature female being observed. This is our primary site we are conducting surveys on, however we are in search of similar sites throughout the area of French Polynesia.

Photo identification

Using imagery to document individual tiger sharks using the facial countershade line, dorsal ridge and pattern, along with any distinct features can help us better understand a population baseline for this region (how many individuals use the area). Photo identification programs also allow us to observe growth rates, pregnancies, wound healing timelines, behavioral change, and more by observing the same individual multiple times over a length of time. Currently we have 36 unique individuals documented at this site ranging from sub-juveniles at less than 1.5 meters in length to our largest, fully mature female nearing 5 meters.

behavioral studies

Understanding the behavior and how it is linked to individual sharks (possibly by size, sex, etc) or how it is linked to environmental factors (possibly by current, tide, visibility, lunar cycle, etc) can help not only provide valuable knowledge on the species but can indicate conditions that are more suitable for positive human-shark interactions as well as times to avoid. Behavioral studies can also provide insight to the cognitive capacity of the species such as how quickly they adapt to patterns, provisional conditioning, and risk vs reward scenarios. Each individual shark is a unique opportunity to learn and no two sharks, even of the exact species, are the same. Social network analysis provides insight into the interactions these sharks may be having in shared environments.

genetic kinship

Understanding the relationship between the individual sharks at this site assists us in better understanding the relationship between these tigers and the importance of protecting juvenile residency areas such as Tiger Lagoon. We are currently attempting to research the genetic kinship between sharks at the study site.

conservation

Our top priority in these studies in these remote locations is to promote a positive message about the tiger sharks and to work in alliance with local fishermen to help them better understand a highly misunderstood and feared species. Through educational programs and communal gatherings we are attempting to bridge the gap between fishermen and shark protectors. The implementation and inclusion of fishermen in this project for citizen science initiatives allows population monitoring by those who are most immersed with the tiger sharks of the lagoon.