Tetiaroa Society Ecostation

24 Oct, 01 AM - 30 Jun, 01 PM

ABSTRACT Coastal nursery areas are widely considered to be critical habitat for sharks, and are of increasing importance given recent declines of many populations across the globe. These essential areas provide habitats for sharks to feed, reproduce, and/or refuge to grow to maturity. Understanding how sharks utilize these habitats, both spatially and temporally, is thus critical for developing species-specific management plans and conservation measures. Previous research has focused on how multiple shark species may inhabit the same nursery, highlighting how habitats may be partitioned in time and space as well as investigating trophic interactions. Less attention, however, has been given to how these dynamics may change in relation to the size/age within a single species. Such ontogenetic shifts in how nursery areas are used could have population level consequences as a result of increased competition, which is likely to have the greatest impact on younger individuals whose survival rates strongly influences population growth rates, particularly for exploited populations. Of the limited studies that have examined differences in movement patterns between age classes, nearly all have been conducted within stressed environments that have experienced varying degrees of fishing pressure and/or habitat degradation. Accordingly, there remains a need to establish a baseline for how sharks utilize these key habitats in a relatively undisturbed ecosystem. Here we propose to study the spatial ecology of a two large marine predators, the sicklefin lemon shark (Negapron acutidens) and blacktip reef sharks (Carcharhinus melanopterus), and how these movement patterns may vary in relation to age/size within a relatively undisturbed nursery: Tetiaroa, French Polynesia. Using a combination of passive acoustic and underwater video data, we will compare how space use within the nursery differs between individuals, as well as across different age classes. Specific metrics to compare between individuals and across different age classes : Residency time, home range size, core use areas, natal homing, time before dispersal from natal site, social networks, influences of environmental factors on these metrics, and changes in species richness and relative abundances of reef fishes. METHODS Our study will be conducted within the small atoll of Tetiaroa, French Polynesia. Using a network of previously deployed (October 2021) VEMCO VR2W (69kHz) acoustic receivers (n=10), we will be able to passively monitor the movements of sicklefin lemon (n=6) and blacktip reef sharks(n=24) that were acoustically tagged in October 2021 (VEMCO acoustic transmitters; V16-H, 69kHz). Receivers will be downloaded and cleaned approximately once a month from October 2022 through June of 2023. Additionally, each receiver has a HOBO Pendant MX Temperature and Light data logger, which continuously collects both temperature and light data. Using this passive acoustic telemetry data, we will compare how space use within the nursery differs between individuals, as well as across different age classes. Furthermore, we will explore how shark movements may influence local reef fish communities by comparing shark movements to species richness and relative abundance data gathered using remote underwater camera systems. These camera systems are non-invasive, minimalist in design (e.g., using GoPro housings), and will be deployed for short durations (e.g., 1 hour) randomly throughout the lagoon. TRIP GOALS We will be making one trip to Tetiaroa under this permit. During this trip, Dr. Aaron Wirsing will lead a visit with researcher Kirk Gastrich and PhD student Aarthi Kannan between October 23 and November 12 of 2022. During this visit, we intend to download and clean all acoustic receivers currently deployed inside Tetiaroa’s lagoon, as well replace receiver batteries (estimated batter life of ~ 15 months). Following this phase, Dr. Wirsing and Mr. Gastrich will return to the US while Aarthi Kannan will remain in Tetiaroa through June 30 of 2023. During this time, she will download acoustic receivers on a monthly basis and a conduct opportunistic underwater video survey deployments.

Visit #78529 @Tetiaroa Society Ecostation

Approved

Under Project # 50266 | Research

Investigating ontogenetic shifts in the Spatial Ecology of Sicklefin lemon (Negaprion acutidens) and blacktip reef sharks (Carcharhinus melanopterus) and their ecological impact in a minimally disturbed nursey habitat

graduate_student - Florida International University

Reservation Members(s)

Aaron Wirsing Oct 24 - 31, 2022 (8 days)
eric CLUA Oct 26 - Nov 2, 2022 (8 days)
Clémentine Séguigne Oct 26 - Nov 2, 2022 (8 days)
Kirk Gastrich Oct 24 - Nov 9, 2022 (17 days)
Aarthi Kannan Oct 24, 2022 - Jun 30, 2023 (250 days)

Reserve Resources(s) | Create Invoice

Ecostation Rate 1 Oct 23 - Nov 9, 2022