Investigating the ecology of reef sharks in Tetiaroa - update 2025

Main objectives

This program aims to study the spatial ecology of two large marine predators—the sicklefin lemon shark ( Negaprion acutidens ) and the blacktip reef shark ( Carcharhinus melanopterus )—within a relatively undisturbed coastal nursery: the lagoon of Tetiaroa. The objective is to better understand how these sharks use nursery habitats according to species, size, and age, in order to establish a scientific baseline in a minimally impacted ecosystem. This knowledge is essential to inform shark management and conservation strategies at both regional and global scales.

Summary of Field Activities

During the November 2025 field mission, the team conducted:

• A full download and redeployment of the existing acoustic monitoring array
• The installation of three additional acoustic listening stations
• Acoustic tagging of 69 sharks: 51 blacktip reef sharks
• 18 sicklefin lemon sharks

To date, the program has tagged 189 sharks (136 blacktip reef sharks and 53 sicklefin lemon sharks), generating over one million acoustic detections within the lagoon.

Impacts and Preliminary Results

Data collected during this mission, combined with previous field campaigns, are now sufficient to support robust statistical analyses. A first scientific manuscript is currently in preparation and will focus on:

• Lagoon habitat use
• Shark movement patterns
• Differences related to species, size, and sex
• Seasonal and diel variations

The broader objective is to improve understanding of atoll shark nursery dynamics, using the protected lagoon of Tetiaroa as a natural laboratory.

Perspectives

The project will continue with ongoing shark tagging and movement monitoring in the Tetiaroa lagoon, alongside data analysis and the preparation of multiple scientific publications. A new field mission is scheduled for March 2026 to continue data collection and deploy additional acoustic tags and receivers, further strengthening the analyses underway.