Pablo Brosset

• PhD
• Professor (Associate) at L'Institut Agro Rennes Angers

Morphometric indices of body condition are assumed to reflect an animal’s health and ultimately its fitness, but their physiological significance remains a matter of debate. These indices are indeed usually considered as proxies of energy reserves, ignoring other physiological processes involved in animal health such as nutritional, immune and horm...

Coastal habitats play a key role in the early life stages of flatfish species, with the quantity and quality of the food they supply being central. However, survival and sufficient development until metamorphosis depend upon obtaining certain essential long-chain polyunsaturated fatty acids (LC-PUFAs). We focused this literature review on flatfish...

The interpretation of δ13C values in trophic ecology requires standardization of the lipid content of organisms estimated through their C:N ratio. To avoid time-consuming lipid extractions, the use of mathematical corrections has been developed for many years, and the conclusions generally point in the direction of species-specific adjustment of th...

Significance Humans are exposed to toxic methylmercury mainly by consuming marine fish. New environmental policies under the Minamata Convention rely on a yet-poorly-known understanding of how mercury emissions translate into fish methylmercury levels. Here, we provide the first detailed map of mercury concentrations from skipjack tuna across the P...

Food characteristics are amongst the most influential factors determining the fish life history traits as quantitative and qualitative changes in individuals' diet can lead to a decline in the energy allocated to their growth, and hence influence natural populations' characteristics. The size-at-age and weight of European sardines (Sardina pilchard...

The benefits of physiological biomarkers, knowledge and concepts are well-established in fish and wildlife management as they confer the ability to understand mechanistic processes, identify cause-and-effect relationships, and develop predictive models. Although this approach is gaining momentum in the context of species conservation, the use of ph...

Animal mortality is difficult to observe in marine systems, preventing a mechanistic understanding of major drivers of fish population dynamics. In particular, starvation is known to be a major cause of mortality at larval stages, but adult mortality is often unknown. In this study, we used a laboratory food-deprivation experiment, on wild caught s...

Climate change has resulted in physical and biological changes in the world's oceans. How the effects of these changes are buffered by top predator populations, and therefore how much plasticity lies at the highest trophic levels, are largely unknown. Here endocrine profiling, longitudinal observations of known individuals over 15 years between 200...

In the oligotrophic context of the Mediterranean Sea, riverine inputs of particulate organic matter represent an important source of food for benthic communities. However, since most of these inputs are delivered during short, but intense flood events, communities living in the vicinity of river mouths are also exposed to strong and frequent physic...

Recruitment is one of the dominant processes regulating fish population productivity. It is, however, notoriously difficult to predict, as it is the result of a complex multi-step process. Various fine-scale drivers might act on the pathway from adult population characteristics to spawning behaviour and egg production, and then to recruitment. Here...

Blue whale survival and fitness are highly contingent on successful food intake during an intense feeding season. Factors affecting time spent at the surface or at depth in a prey patch are likely to alter foraging effort, net energy gain, and fitness. We specifically examined the energetic consequences of a demonstrated reduction in dive duration...

We investigated the effect of environmental conditions on Atlantic mackerel spawning habitat in the southern Gulf of St. Lawrence (sGSL). Based on generalized additive models, we (i) modelled the optimal spawning habitat of mackerel in the sGSL using daily egg production (DEP) in June, (ii) predicted known and new potential present spawning habitat...

The true spatiotemporal structure of a fish population is often more complex than represented in assessments because movement between spawning components is disregarded and data at the necessary scale are unavailable. This can generate poor advice. We explore the impacts of modelling choices and their associated risks given limited data and lack of...

Climate variability, fishing and predation are the main factors affecting fish population dynamics. In this study, the drivers of population growth variability were investigated for 7 fish stocks (2 cod, 4 herring and 1 mackerel stock) in the Gulf of St. Lawrence (NW Atlantic). The annual population growth sensitivity to both recruitment and surviv...

Climate and density-dependent effects are important drivers of recruitment (R). In the Gulf of St. Lawrence (GSL), recent years indicated an exceptional warming of water associated with variations in plankton phenology and fish abundance. At the same time, northern shrimp (Pandalus borealis) recruitment and stock dynamics fluctuated greatly, but th...

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...

The factors affecting herring recruitment are still poorly understood, complicating the prediction of stock dynamics and the choice of operational management strategies. We investigated effects of intrinsic (SSB) and extrinsic factors (physical and biological environments, including competition and predation) on recruitment of the spring and fall s...

Population dynamics of Atlantic herring in the Gulf of St Lawrence (GSL) need to be investigated, especially considering their ecological and economical importance. Recruitment, in particular, is highly variable and constitutes a major source of uncertainty for stock management. Our first objective was to assess the role of intrinsic (spawning stoc...

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...

L’écosystème pélagique du Golfe du Lion a subi un changement très marqué de la dynamique de population des poissons petits pélagiques depuis 2008. L'anchois (Engraulis encrasicolus) et la sardine (Sardina pilchardus), exploités économiquement, sont devenus plus petits et plus maigres tandis que le sprat (Sprattus sprattus), non exploité car de faib...

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...

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....

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...

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...

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...

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...