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Introduction
Publications
Publications (204)
Human activities and climate change have negatively affected the world’s oceans, leading to a decline of 30 to 60 % in coastal ecosystems’ biodiversity and habitats. The projected increase in the human population to 9.7 billion by 2050 raises concerns about the sustainability of marine ecosystem conservation and exploitation. Marine turtles, as sen...
In marine ecosystems, the presence of trace elements resulting from anthropogenic activities has raised concerns regarding their potential effects on marine organisms. This study delves into the intricate relationship between trace element contamination and the physiological responses of a key marine species in the Mediterranean Sea: the European s...
The intensification of warming-induced mass-mortalities in invertebrate populations including in temperate regions is a critical global issue. Mesophotic zones (30–150 m depth) have been suggested as potential refuges from climate change for gorgonian populations, offering hope for reseeding damaged shallow populations. Using a proteomic approach,...
The commercially important Atlantic bluefin tuna ( Thunnus thynnus ), a large migratory fish, has experienced notable recovery aided by accurate resource assessment and effective fisheries management efforts. Traditionally, this species has been perceived as consisting of eastern and western populations, spawning respectively in the Mediterranean S...
The increase in trace element concentrations in the aquatic environment due to anthropogenic activities, urges the need for their monitoring and potential toxicity, persistence, bioaccumulation, and biomagnification at different trophic levels. Gilthead seabream is a species of commercial importance in the Mediterranean Sea, both for the aquacultur...
To limit climate warming to 2°C above preindustrial levels, most economic sectors will need a rapid transformation toward a net zero emission of CO2 . Tuna fisheries is a key food production sector that burns fossil fuel to operate but also reduces the deadfall of large-bodied fish so the capacity of this natural carbon pump to deep sea. Yet, the c...
The commercially important Atlantic bluefin tuna (Thunnus thynnus), a large migratory fish, has experienced notable recovery aided by accurate resource assessment and effective fisheries management efforts. Traditionally, this species has been perceived as consisting of eastern and western populations, spawning respectively in the Mediterranean Sea...
The intensification of warming-induced mass-mortalities in invertebrate populations is a critical phenomenon that affects many regions worldwide, including temperate ones. Mesophotic zones (from 30 to 150 meters depth) have been hypothesized to provide refuge from climate change to gorgonian populations, a promise for re-seeding damaged or destroye...
Since 2008, there has been a major decrease in the numbers of old and large sardines in the Gulf of Lions, which has had a major effect on regional fisheries. A bottom-up process involving a shift in diet towards smaller planktonic prey has been suggested as the main driver of this development. Yet, the reproductive capacities of the sardines have...
Global warming is causing profound modifications of aquatic ecosystems and one major outcome appears to be a decline in adult size of many fish species. Over the last decade, sardine populations in the Gulf of Lions (NW Mediterranean Sea) have shown severe declines in body size and condition as well as disappearance of the oldest individuals, which...
Atlantic bluefin tuna (ABFT) is a migratory species whose exploitation is affected by its migratory behaviour. ABFT can be found the whole year round in the Gulf of Lions (GoL), with the exception of the May/June/July spawning season. The date at which ABFT fishing resumes in the GoL after spawning is variable and affects both the summer longline f...
Atlantic bluefin tuna (Thunnus thynnus) (ABFT) frequently engage in surface basking and foraging behaviour that makes them detectable from afar. This behaviour is utilized for the development of fisheries-independent abundance indices based on aerial surveys, although changes in the surface-feeding dynamics of ABFT are not yet accounted for. We inv...
An important decrease in small pelagic fish condition and size has been observed in the most productive ecosystem of the Mediterranean Sea, the Gulf of Lions, since 2008, leading to an important fishery crisis. Previous studies suggested bottom-up control to be the most probable cause for these changes. Here, we investigate whether an environmental...
Effective sustainable management of marine fisheries requires that assessed management units (that is, fish stocks) correspond to biological populations. This issue has long been discussed in the context of Atlantic bluefin tuna (ABFT, Thunnus thynnus) management, which currently considers two unmixed stocks but does not take into account how indiv...
Small pelagic fish are key components of marine ecosystems and fisheries worldwide. Despite the absence of recruitment failure and overfishing, pelagic fisheries have been in crisis for a decade in the Western Mediterranean Sea because of a marked decline in sardine size and condition. This situation most probably results from bottom-up control and...
This study investigates the association between an index of mesozooplankton biomass, derived from the Continuous Plankton Recorder survey and satellite-derived productivity fronts in the North Atlantic. While chlorophyll-a content (CHL) is commonly described as a proxy for phytoplankton biomass, the size of productivity fronts estimated from the ho...
Anticipating future changes in marine social‐ecological systems (MSES) several decades into the future is essential in the context of accelerating global change. This is challenging in situations where actors do not share common understandings, practices, or visions about the future. We introduce a dedicated scenario method for the development of M...
Sardine Sardina pilchardus, anchovy Engraulis encrasicolus and European hake Merluccius merluccius represent a significant part of the commercial landings in the Gulf of Lions (northwestern Mediterranean Sea). However, their stocks have shown severe declines during the last decades due to fishing pressure and/or environmental changes. The aim of th...
Understanding whether recruitment fluctuations in fish stock arise from stochastic forcing (e.g. environmental variations) rather than deterministic forces (e.g. intrinsic dynamics) is a long standing question with important applied consequences for fisheries ecology. In particular, the relationship between recruitment, spawning stock biomass and e...
Around 2008, an ecosystem shift occurred in the Gulf of Lions, highlighted by considerable changes in biomass and fish mean weight of its two main small pelagic fish stocks (European anchovy, Engraulis encrasicolus; European sardine, Sardina pilchardus). Surprisingly these changes did not appear to be mediated by a decrease in fish recruitment rate...
Overfishing causes frequent fish population collapses but rare extinctions
Building multiple-perspective scenarios is one way to get prepared for the future. In June 2016 a workshop was organised in Sommarøya (close to Tromsø) to explore the possible futures of the Barents Sea social ecological systems using a new method for building multiple-perspective scenarios. In this poster, you can construct your own multiperspecti...
We investigated the habitat utilization, vertical and horizontal behaviour of Atlantic bluefin tuna Thunnus thynnus (ABFT) in relation to oceanographic conditions in the northwestern Mediterranean Sea, based on 36 pop-up archival tags and different environmental data sets. Tags were deployed on early mature ABFT (127–255 cm) between July and Novemb...
This synthesis explores the complex patterns of marine dispersal and connectivity at multiple spatial and temporal scales and identifies major gaps of knowledge. In recent years these processes have become much better known, thanks to the development of new technological tools and methods such as tagging and tracking of migratory vertebrates across...
The European hake, Merluccius merluccius, is an important resource for Mediterranean fisheries. This study focuses on juvenile and adult hake feeding ecology in the Gulf of Lions, using information from scientific surveys carried out during two seasons and three years (2004-2006). Stomach content and stable isotope (δ15N, δ13C) analyses were perfor...
Recently, the abundance of young Atlantic bluefin tuna (Thunnus thynnus) tripled in the northwestern Mediterranean following effective management measures. We investigated whether its predation on sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) could explain their concurrent size and biomass decline, which caused a fishery crisis....
Small pelagic fish are among the most ecologically and economically important marine fish species and are characterized by large fluctuations all over the world. In the Mediterranean Sea, low catches and biomass of anchovies and sardines have been described in some areas during the last decade, resulting in important fisheries crises. Therefore, we...
Many highly mobile species are known to use persistent pathways or corridors to move between habitat patches in which conditions are favorable for particular activities, such as breeding or foraging. In the marine realm, environmental variability can lead to the development of temporary periods of anomalous oceanographic conditions that can connect...
Sardine populations worldwide can fluctuate drastically over short time periods, in terms of both biomass and biological characteristics. Fluctuations might be amplified by pathogens, but such hypotheses have never been considered in the absence of clear macroscopic symptoms. In the Gulf of Lions (NW Mediterranean), an enduring severe decrease in s...
Limited resources in the environment prevent individuals from simultaneously maximizing all life-history traits, resulting in trade-offs. In particular, the cost of reproduction is well known to negatively affect energy investment in growth and maintenance. Here, we investigated these trade-offs during contrasting periods of high versus low fish si...
Limited resources in the environment prevent individuals from simultaneously maximizing all life history traits, resulting in trade-offs. In particular, the cost of reproduction is well known to negatively affect energy investment in growth and maintenance. Here, we investigated these trade-offs during contrasted periods of high versus low fish siz...
Since 2008, a severe decrease in size and body condition together with a demographic truncation has been observed in sardine (secondarily in anchovy) population of the Gulf of Lions (NW Mediterranean Sea). In parallel, sprat biomass, which was negligible before, has increased tenfold. All these changes have strongly affected the regional fisheries....
An improved knowledge of habitat utilization by demersal species is a pre-requisite for their spatial management. Based on scientific survey data collected over the period 1994-2010, the present study investigates relationships between 4 environmental factors and 10 demersal species in the Gulf of Lions (northwestern Mediterranean Sea). Generalized...
Commercial tunas and billfishes (swordfish, marlins and sailfish) provide considerable catches and income in both developed and developing countries. These stocks vary in status from lightly exploited to rebuilding to severely depleted. Previous studies suggested that this variability could result from differences in life-history characteristics an...
Since 2007, the biomass of sardine and anchovy in the NW Mediterranean has remained persistently low, whereas the biomass
of the commercially low-valued sprat has exploded. Also, simultaneous decreases in condition, size, and/or age of these populations
were observed. Altogether, this resulted in a drop in landings of small pelagics. To understand...
An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5-25kg, only feeding) and large (> 25kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. te...
Pop-up archival tags (PAT) provide summary and high-resolution time series data at predefined temporal intervals. The limited battery capabilities of PATs often restrict the transmission success and thus temporal coverage of both data products. While summary data are usually less affected by this problem, as a result of its lower size, it might be...
Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to pro...
Conservation and management measures for exploited fish species rely on our ability to monitor variations in population abundance. In the case of the eastern stock of Atlantic bluefin tuna (ABFT), recent changes in management policies have strongly affected the reliability of fishery-dependent indicators due to drastic changes in fishing season/are...
Increasing human pressures and global environmental change may severely affect the diversity of species assemblages and associated ecosystem services. Despite the recent interest in phylogenetic and functional diversity, our knowledge on large spatio-temporal patterns of demersal fish diversity sampled by trawling remains still incomplete, notably...
Endogenous and environmental variables are fundamental in explaining variations in fish condition. Based on more than 20 yr of fish weight and length data, relative condition indices were computed for anchovy and sardine caught in the Gulf of Lions. Classification and regression trees (CART) were used to identify endogenous factors affecting fish c...
Mapping diversity indices, that is estimating values in all locations of a given area from some sampled locations, is central to numerous research and applied fields in ecology.
Two approaches are used to map diversity indices without including abiotic or biotic variables: (i) the indirect approach, which consists in estimating each individual spec...
Three body condition indices were compared in three small pelagic fish species.•Bioenergetic index (fatmeter) correlated well with biochemical lipid estimation.•The morphometric index appears more integrative and reflects more than just lipids.•Fatmeter repeatability was high and frozen storage did not affect its measurements.•The fatmeter allows t...
Two stocks of bluefin tuna (Thunnus thynnus) inhabit the north Atlantic; the western and eastern stocks spawn in the Gulf of Mexico and the Mediterranean Sea respectively. Trans-Atlantic movements occur outside spawning time whereas natal homing maintains stock structure. Commercial fisheries may exploit a mixed assemblage of both stocks. The incor...
In spite of its pivotal role in future implementations of the Ecosystem Approach to Fisheries Management, current knowledge about tuna habitat preferences remains fragmented and heterogeneous, because it relies mainly on regional or local studies that have used a variety of approaches making them difficult to combine. Therefore in this study we ana...
The relationship between spawning fish abundance and the number of offspring, the so-called stock-recruitment relationship, is crucial for fisheries management and conservation measures. Using the most comprehensive data set ever assembled, we quantify this relationship for 211 fish stocks worldwide, revealing a global pattern with a pervasive asym...
Understanding the ecological and anthropogenic drivers of population dynamics requires detailed studies on habitat selection and spatial distribution. Although small pelagic fish aggregate in large shoals and usually exhibit important spatial structure, their dynamics in time and space remain unpredictable and challenging. In the Gulf of Lions (nor...
We analyse fish diversity by a multiple indices and scales approach over 19 years.•Species richness and evenness are proxies of phylogenetic and functional components.•Species richness reveals hotspots for different spatial scales contrary to evenness.•All diversity components remains stable over the last two decades.
Fish stock fluctuations are affected by two potentially confounding forces: the removal of individuals by fisheries and climatic
variations affecting the productivity of fish populations. Disentangling the relative importance of these forces has thus
been a question of primary importance for fisheries management and conservation. Through the analys...
Since 2000, Ifremer has conducted yearly aerial surveys during late summer-early fall on juvenile Atlantic bluefin tuna (ABFT) in the Northwestern Mediterranean in order to calculate a fishery-independent index of abundance. This scientific survey provides crucial information for stock assessment, in particular because juvenile ABFT are no longer t...
The relative value-of-information for model based and empirical Management Procedures is compared for Mediterranean bluefin tuna using Management Strategy Evaluation. This is done by conditioning an Operating Model on alternative hypotheses about population and fishery dynamics. Data, fisheries and fisheries independent are sampled from the Operati...
Since 2007, the ecosystem of the Gulf of Lions has shifted to a different regime, characterised by a low anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) biomass and a remarkably high sprat (Sprattus sprattus) biomass. Surprisingly, the abundance and recruitment of anchovy and sardine remained high. To understand which processes (b...
The recent overexploitation of East Atlantic and Mediterranean bluefin tuna stock has been well documented in the media where it has become the archetype of overfishing and general mis-management. Beyond the public debate, the crisis also highlighted how the interactions between science and management can change through time according to the awaren...
In spite of its pivotal role in future implementations of the Ecosystem Approach to Fisheries Management, current knowledge about tuna habitat preferences remains fragmented and heterogeneous, because it relies mainly on regional or local studies that have used a variety of approaches making them difficult to combine. Therefore in this study we ana...
This study presents the results of an electronic tagging programme on mature Atlantic bluefin tuna (ABFT) that has been conducted
since 2007 offshore of the French Mediterranean Coast. The spatial distributions of ABFT showed little year-to-year variation
and the fish concentrated in a small area of the central northwestern Mediterranean, where the...
One of the aims of the EU project STROMBOLI (2000-2002) was to conduct an aerial survey for bluefin tuna in the western Mediterranean Sea to test the feasibility of computing an index of abundance from direct observation. This approach has at least two advantages: (i) to provide fishery-independent information and observation, and (ii) to compensat...