Conflicts between fishermen and marine megafauna, exacerbated by the intensification of industrial fishing and the decline in marine resources, raise complex issues for marine socio-ecosystems. Margaux Mollier’s thesis as part of the french Ocean & Climate Priority Research Programme (PPR) explores these interactions between human activities and marine fauna. By aiming for a better understanding of conflicts and governance levers, this multidisciplinary research combining social and ecological sciences aims to offer sustainable and balanced solutions for a viable coexistence between fisheries and threatened species.
By Carole Saout-Grit and Laurie Henry
Growing pressure on marine ecosystems
The expansion of industrial fishing over the last six decades, combined with a significant decline in fish stocks, has contributed to an increase in interactions between fishermen and marine megafauna – sharks, marine mammals, seabirds and turtles.
These interactions often take the form of accidental catches (catches of marine species not targeted by fishermen) and depredation, when the animals consume part of the catch directly on the fishing gear. Depredation is behaviour that is often perceived by fishermen as direct competition, resulting in economic losses for fishermen, damage to property and an increase in the workload required to compensate for these losses.
Accidental catches or degradation cause damage to fishermen and threaten the survival of already vulnerable marine species. © M.Mollier
The impacts of conflicts between fisheries and megafauna are not limited to economic aspects. They also affect the survival of animal species and the health of marine ecosystems. These conflicts contribute to the decline of many already vulnerable species, making the resolution of this issue crucial to the preservation of ecosystems.
The solutions proposed to date have often been unilateral and mono-sectoral, focusing on the protection of fishery resources or the conservation of biodiversity, without taking into account the entire social and ecological system. A partial approach that leads to many unresolved conflicts that continue to escalate.
An integrated, interdisciplinary research approach
Margaux Mollier has long been fascinated by the ocean, and her academic career has focused on marine ecology, with a passion for preserving marine ecosystems.
Now a doctoral student at the EUCLIDE Doctoral School in the MARBEC joint research unit (University of Montpellier/CNRS/Ifremer/IRD) in Sète, she is working on an innovative thesis combining social sciences and ecology to analyse the conflicts between fisheries and large marine predators.
© M.Mollier
His project is funded by the PPR Océan & Climat, which aims to promote the sustainable use of ocean resources while preserving marine biodiversity. The thesis is co-directed by Camille Mazé(CNRS) and Paul Tixier (IRD) for the period 2023-2026.
Through collaboration between experts in anthropology, sociology and marine ecology, and by exploiting complex modelling tools, Margaux hopes to find viable solutions to mitigate long-term conflicts between human activities and marine ecosystems.
A case study of two zones and three areas of research to understand and reduce conflicts
Margaux Mollier’s thesis examines a case of conflict between fisheries and marine megafauna (depredation) in two very specific areas: the French Southern Territories (Crozet and Kerguelen Islands) and New Caledonia, two ultra-marine areas with contrasting socio-ecological configurations.
In the French Southern Territories, where the number of vessels and players is limited and fishing activity is tightly controlled, conflicts are concentrated around fishing for the highly prized Patagonian toothfish. Here, killer whales and sperm whales take around 30% of catches on longlines. These interactions, which began in the 1990s, now represent a major economic constraint for fishermen and can have ecological impacts on predators and associated ecosystems.
In New Caledonia, conflicts are taking on a new dimension, particularly around tuna fishing. This type of fishing involves a larger fleet, with no systematic fisheries inspectors. Interactions involve certain species of sharks and cetaceans, exacerbated by the global decline in tuna stocks and the major conservation issue for several species of megafauna. Unlike the Southern Territories, New Caledonia represents a complex socio-ecological system, where competition for resources is accentuated by more diversified local socio-economic considerations.
Close collaboration between fishermen, decision-makers and scientists is needed to resolve conflicts between fisheries and marine megafauna. © M.Mollier
The research project focuses on three main areas to assess, understand and mitigate conflicts between fishermen and marine megafauna:
- Assessing the intensity of conflicts and their socio-economic and ecological impacts, by quantifying the scale of the conflicts and their economic and ecological repercussions
- Analyse the anthropogenic and ecological factors behind conflicts, seeking to identify the causes of conflicts by examining human practices (fishing techniques, areas of activity) and ecological factors.
- Exploring management levers and behavioural adaptations, by identifying management solutions and adjustments to fishing practices to minimise conflicts.
Margaux Mollier relies on close collaboration between fishermen, managers and scientists to design solutions tailored to the local context, taking into account socio-economic needs and species conservation. Through this innovative, interdisciplinary approach based on three themes and two specific case studies, she aims to improve coexistence between fishermen and marine fauna by identifying ways in which marine ecosystems can become more resilient, while at the same time preserving human activities.
3 Questions to Margaux Mollier
Why did you decide to do a PhD in marine sciences?
I’ve always been fascinated by the ocean, so it was natural for me to do a Masters in marine ecology, during which I was able to acquire knowledge about this complex system and the issues involved in preserving it. Doing a thesis in marine sciences is therefore an opportunity to apply my skills and learn more about the different components of this system and their interactions, in order to reconcile human activities with the preservation of marine biodiversity.
What made you want to do this thesis? What were your motivations?
This thesis, co-constructed with Paul Tixier and Camille Mazé, combines marine ecology and social sciences with the aim of identifying the ecological and sociological factors behind the conflict between large predators and fishing gear, which can have major ecological and socio-economic consequences. I therefore feel that I can provide knowledge that is essential to the development of solutions to mitigate this conflict, by bringing together several disciplines and acting as a link between research and those involved in fishing activities.
How do you see your future after this thesis?
I’d like to continue in research and in the theme of my thesis through a post-doctorate, preferably abroad. In the longer term, my career path hasn’t yet been defined, but I like the idea of doing more applied research and being in direct contact with other non-scientific professionals. I need to feel useful and passionate about my work.
Référence : Mollier, Margaux, « From conflict to coexistence: understanding the sociological and ecological mechanisms of use between fisheries and marine megafauna to identify solutions », phD 2023-2026
Contact : margaux.mollier@ird.fr