The association is built on five core pillars: Integrity, Rigor, Collaboration, Responsibility, and Innovation. This project would not be possible without the support of the City of Royan, IFREMER, and numerous local partners.
The Mission Thon Rouge association works in close collaboration with major players in scientific research and maritime safety.
Orca Ecology and Bluefin Tuna
By Renaud de Stephanis, researcher and founder of the CIRCE association (Conservación, Información y Estudio sobre Cetáceos).
Orcas (Orcinus orca) frequenting the Strait of Gibraltar and the Gulf of Cádiz constitute a small, highly specialized population whose ecology is closely linked to Atlantic bluefin tuna (Thunnus thynnus). During the spring tuna migration toward the Mediterranean, these orcas take advantage of the abundance of prey and develop particularly effective hunting strategies. This phenomenon represents one of the clearest examples of trophic specialization among cetaceans in European waters.
"Understanding these dynamics is essential for moving toward solutions that allow for the coexistence of fishing activities and the conservation of orcas in the Strait. These animals represent an exceptional natural heritage, the protection of which largely depends on our collective ability to understand and manage the complex relationships between marine predators, fishery resources, and human activities."
Interactions between orcas and traditional tuna fishing, notably handline or longline fishing, have been documented for several decades. In many cases, orcas take advantage of tuna caught on lines, partially or totally removing them before fishermen can retrieve them. This behavior, known as depredation, can lead to economic losses for the fishing fleet and has historically been a source of conflict.
However, these interactions also provide a unique opportunity to better understand the ecology and behavior of this orca population. Through photo-identification studies, satellite tracking, and direct observations at sea, it is possible to analyze the orcas' use of space, how these feeding strategies are learned and transmitted, as well as their relationship with the migratory dynamics of bluefin tuna.
Our team has been studying orcas in the Strait of Gibraltar from 1999 to the present day, as part of one of the most comprehensive long-term monitoring programs dedicated to this population. Over more than two decades of work, we have combined various approaches—photo-identification, satellite tagging, acoustics, and direct observations—to better understand their behavior, social structure, and interactions with human activities.
"During this conference, I will present some of the most important results obtained over these years of research, as well as the recent evolution of interactions between orcas and fisheries. I will also explain how different stakeholders—fishermen, mariners, institutions, or citizens—can contribute to scientific monitoring and the conservation of this unique population."
Safety at Sea
By Arnaud Gayrin, President of the National Sea Rescue Society (SNSM) Royan.
Off the coasts of Charente and Gironde, a unique collaboration brings together Mission Thon Rouge, the Royan National Sea Rescue Society, and IFREMER scientists around a common goal: to better understand Atlantic bluefin tuna. Through No-Kill tagging, this project embodies the intersection of science, a passion for the ocean, and maritime commitment.
"Together, we transform every trip to sea into a concrete action for the knowledge of bluefin tuna."