Detecting, Predicting and Protecting Pelagic Megafauna Hotspots in the Coral Sea

Informations projet

MEGAFAUNA

N° de convention de subvention: 845178

DOI

10.3030/845178

Projet clôturé

Date de signature de la CE 17 Avril 2019

Date de début 1 Février 2020

Date de fin 31 Janvier 2022

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 196 707,84

Contribution de l’UE

€ 196 707,84

Coordonné par

UNIVERSITE DE MONTPELLIER
France

Periodic Reporting for period 1 - MEGAFAUNA (Detecting, Predicting and Protecting Pelagic Megafauna Hotspots in the Coral Sea)

Période du rapport: 2020-02-01 au 2022-01-31

Résumé du contexte et des objectifs généraux du projet

Marine megafauna, including marine mammals, sea turtles, sharks and rays, plays critical roles in marine ecosystems such as food webs regulation and nutrients transfer. Aside from these key ecological functions, marine megafauna also provides important socio-economic benefits to society through ecotourism, as many species in this group are charismatic. However, marine megafauna is highly threatened worldwide due to cumulative human-derived pressures from fishing, habitat loss, pollution, and climate change. Together, these pressures have triggered population declines and many species are now rare or on the brink of extinction. Efficient and fast techniques are thus urgently needed to survey marine megafauna in space and time and inform the strategic placement of new marine reserves for their effective conservation. Delineating key areas for conservation is particularly timely given the new ambitious target of protecting 30% of the ocean by 2030.

This project focused on New Caledonia, an overseas Territory of France that hosts an exceptional diversity of marine megafauna species, half of which are listed as threatened by the IUCN. The objectives of this project were: (1) to develop a novel cutting-edge technique to detect marine megafauna in New Caledonia, (2) to derive maps of marine megafauna hotspots in these waters, and (3) to design a network of reserves effectively protecting marine megafauna across New Caledonia.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

The covid crisis 2 months after the start of the project prevented my planned fieldwork in New Caledonia. I was able to cope with this challenge by remotely organizing data collection through a collaboration with a local tourism company, which uses a light airplane to fly tourists over the lagoon of Poé (western coast of New Caledonia). We fitted a Gopro camera underneath the plane to collect aerial videos of marine megafauna. This collaboration allowed us to collect over 50 hours of aerial videos, many of which included marine megafauna observations. We analyzed these videos with deep learning models for the detection of two key species of marine megafauna (dugongs and eagle rays) (objective 1) and for the mapping of eagle rays in the Poé lagoon (objective 2). The work on dugong detection is published in Conservation Biology. The work on eagle rays detection and mapping was conducted through the mentoring of a Master student and is published in Biological Conservation. I also communicated this work to the public, through an article for children (accepted in Frontiers for Young Minds), press releases in French and English, and an article on the University of Montpellier website. Furthermore, I communicated this work to conservationists and managers through an invited presentation at the IUCN World Conservation Congress in Marseille.

My trip to New Caledonia became possible in May 2021. During my mission in New Caledonia, I conducted a dedicated survey of marine megafauna, using the same airplane but flying over pre-determined transects. In total, we collected 45 hours of videos over a much broader area of the western lagoon of New Caledonia. The analysis of these videos for the mapping of marine megafauna hotspots is in progress (objective 2). This trip also gave me the opportunity to present the survey and its initial results to local managers in New Caledonia. I also made a video for the public (available on my Youtube channel) explaining how the survey takes place and which species we can observe from the air.

To pursue objective 3 (designing a reserve network) ) in spite of delays in the survey data collection and analysis, I relied on an extensive database of shark abundance collected from baited remote underwater cameras by my collaborators in New Caledonia. I analyzed this database with systematic conservation planning algorithms in order to design the reserve network most effectively protecting sharks in New Caledonia. A paper is in preparation for submission to a journal in 2022.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

Until now the distribution and abundance of marine megafauna was assessed using a variety of methods with limitations in their data acquisition. Underwater visual surveys from scuba divers and baited videos systems are traditionally used to detect and count marine megafauna (especially sharks) but they remain limited in terms of spatial and temporal coverage and fail to detect elusive species. Tagging techniques faces limitations, including the high costs of tags, the challenge of deploying them on individuals and the often low spatial resolution of the data. Observer-based surveys from airplanes have the ability to detect many megafauna species across large spatio-temporal scales. However, they are very costly and can suffer from observation biases caused by observers’ fatigue and subjective perception of the environment. Thus, a new, unbiased, and reproducible survey method is needed to assess the distribution and abundance of marine megafauna across large and temporal scales.

The main achievements of this project are:
(1) A novel method for monitoring threatened marine megafauna in coral reef ecosystems by coupling aerial imagery and cutting-edge deep learning models
(2) Groundbreaking maps of marine megafauna hotspots in New Caledonia and statistical models to predict these hotspots
(3) A reserve network to effectively protect sharks at the scale of the New Caledonian archipelago

The results of this project are important for marine megafauna conservation in New Caledonia and beyond. The survey method and novel maps will help managers of the New Caledonia Provinces to monitor populations, assess the effectiveness of existing reserves, and identify critical habitats needing protection. This cost-effective survey method is also widely exportable to other tropical regions such as Mayotte, the Maldives and Indonesia. It will be particularly useful to define priority areas for marine megafauna conservation in regions where protection is urgently needed due to declining populations (e.g. some parts of Indonesia). Hence the project results have the potential to help expand marine reserves worldwide, thereby contributing to the 30 x 30 objective endorsed my many European countries that aims at protecting 30% of the world’s oceans by 2030.

This project also provided to the public an exciting application of new technologies (imagery and artificial intelligence algorithms) to the conservation of charismatic marine species. The project made available to the public appealing videos, images and maps of marine megafauna through an online video, press releases and popularization articles. I hope these materials helped raised the public’s interests on the conservation and ecology of these threatened species.

Map of megafauna hotspots (here seaturles) in the Poé lagoon in New Caledonia

Images of the camera fitted under the plane and some encountered megafauna species