There is an urgent need for developing policy-relevant future scenarios of biodiversity and ecosy... more There is an urgent need for developing policy-relevant future scenarios of biodiversity and ecosystem services. This paper is a milestone toward this aim focusing on open ocean fisheries. We develop five contrasting Oceanic System Pathways (OSPs), based on the existing five archetypal worlds of Shared Socioeconomic Pathways (SSPs) developed for climate change research (e.g., Nakicenovic et al., 2014 and Riahi et al., 2016). First, we specify the boundaries of the oceanic social-ecological system under focus. Second, the two major driving forces of oceanic social-ecological systems are identified in each of three domains, viz., economy, management and governance. For each OSP (OSP1 " sustainability first " , OSP2 " conventional trends " , OSP3 " dislocation " , OSP4 " global elite and inequality " , OSP5 " high tech and market "), a storyline is outlined describing the evolution of the driving forces with the corresponding SSP. Finally, we compare the different pathways of oceanic social-ecological systems by projecting them in the two-dimensional spaces defined by the driving forces, in each of the economy, management and governance domains. We expect that the OSPs will serve as a common basis for future model-based scenario studies in the context of the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES).
The basic components of an age-size and space-time structured statistical stock assessment model ... more The basic components of an age-size and space-time structured statistical stock assessment model are presented. The model could be flexible enough to capture some of the main population dynamics features observed in many tuna populations. The model could be applied to bigeye tuna (Thunnus obesus) data in the Atlantic Ocean. RÉSUMÉ Les éléments fondamentaux d=un modèle d=évaluation de stock structuré dans l=espace et dans le temps sont présentés ici. Le modèle pourrait être suffisamment flexible pour appréhender certains des aspects principaux de la dynamique des populations qui sont observés dans nombre de stocks de thon. Le modèle pourrait être appliqué aux données sur le thon obèse (Thunnus obesus) dans l=Atlantique. RESUMEN Se presentan los componentes básicos de un modelo de evaluación estadística del stock estructurado espacio-temporalmente y por edad-talla. El modelo puede ser lo suficientemente flexible para detectar algunos de los rasgos principales de dinámica de poblaciones observados en muchas poblaciones de túnidos. El modelo puede aplicarse a los datos de patudo (Thunnus obesus) del océano Atlántico.
The IOTC will soon implement a large tagging program in the Indian Ocean in order to obtain the p... more The IOTC will soon implement a large tagging program in the Indian Ocean in order to obtain the parameters needed to achieve reliable stock assessment for the target tropical tuna species, bigeye, yellowfin and skipjack. One of the first step of this work is the simulation of tag-recapture experiments. For that purpose, a habitat based tuna spatial dynamics model has
We develop an advection-difiusion size-structured flsh population dynamics model and apply it to ... more We develop an advection-difiusion size-structured flsh population dynamics model and apply it to simulate the skipjack tuna population in the Indian Ocean. The model is fully spatialized, and movements are parame- terized with oceanographical and biological data; thus it naturally reacts to environment changes. We flrst formulate an initial-boundary value problem and prove existence of a unique positive solution. We
The model PROCEAN (PROduction Catch-Effort Analysis) is a bayesian statistical catch/effort analy... more The model PROCEAN (PROduction Catch-Effort Analysis) is a bayesian statistical catch/effort analysis framework based on a generalized production model. The use of such a production model could be usefull in IOTC where reliable size data are missing for stock assessment. The aim of this paper is to present the PROCEAN model. PROCEAN is a multi-fleet non equilibrium generalized production model which includes process error for both catchability time series and carrying capacity of the stock. PROCEAN assumes that fluctuations of the stock surface may only have consequences on fleets catchability and on the stock carrying capacity. Our objective is not to propose a very realistic representation of the fishery. We propose a tool to extract the maximum amount of information from the data set by structuring it given a simple and well established theoretical model. Then, modeling is used here as a mean to explore data sets according to various hypothesis.
The IOTC initiated a discussion to organize a large scale tagging program concerning the major tr... more The IOTC initiated a discussion to organize a large scale tagging program concerning the major tropical tuna species and fisheries. According to the terms of reference for the working party on tagging (Anon., 1999), prospective simulations are needed to help designing tag-recapture experiments. The purpose of this paper is to present the methodology developed to help designing the future tagging
Bioaccumulation is difficult to document because responses differ among chemical compounds, with ... more Bioaccumulation is difficult to document because responses differ among chemical compounds, with environmental conditions, and physiological processes characteristic of each species. We use a mechanistic model, based on the Dynamic Energy Budget (DEB) theory, to take into account this complexity and study factors impacting accumulation of organic pollutants in fish through ontogeny. The bioaccumulation model proposed is a comprehensive approach that relates evolution of hake PCB contamination to physiological information about the fish, such as diet, metabolism, reserve and reproduction status. The species studied is the European hake (Merluccius merluccius, L. 1758). The model is applied to study the total concentration and the lipid normalised concentration of 4 PCB congeners in male and female hakes from the Gulf of Lions (NW Mediterranean sea) and the Bay of Biscay (NE Atlantic ocean). Outputs of the model compare consistently to measurements over the life span of fish. Simulation results clearly demonstrate the relative effects of food contamination, growth and reproduction on the PCB bioaccumulation in hake. The same species living in different habitats and exposed to different PCB prey concentrations exhibit marked difference in the body accumulation of PCBs. At the adult stage, female hakes have a lower PCB concentration compared to males for a given length. We successfully simulated these sex-specific PCB concentrations by considering two mechanisms: a higher energy allocation to growth for females and a transfer of PCBs from the female to its eggs when allocating lipids from reserve to eggs. Finally, by its mechanistic description of physiological processes, the model is relevant for other species and sets the stage for a mechanistic understanding of toxicity and ecological effects of organic contaminants in marine organisms.
This paper gives an overview of the ecosystem model APECOSM (Apex Predators ECOSystem Model) whic... more This paper gives an overview of the ecosystem model APECOSM (Apex Predators ECOSystem Model) which is developed in the framework of the GLOBEC-CLIOTOP Programme. APECOSM represents the flow of energy through the ecosystem with a size-resolved structure in both space and time. The uptake and use of energy for growth, maintenance and reproduction by the organisms are modelled according to the DEB (dynamic energy budget) theory and the size-structured nature of predation is explicit. The pelagic community is divided into epipelagic and mesopelagic groups, the latter being subdivided into vertically migrant and non-migrant species. The model is mass-conservative. Energy is provided as the basis of the model through primary production and transferred through 3D spatially explicit size-spectra. Focus species (tunas at present, but any predator species can be considered) are ''extracted" from the global size-spectra without losing mass balance and represented with more physiological and behavioural details. The forcing effects of temperature, currents, light, oxygen, primary production and fishing are explicitly taken into account.
The goal of this paper is to present a generic multi-region nonlinear age-size structured fish po... more The goal of this paper is to present a generic multi-region nonlinear age-size structured fish population model, and to assess its mathematical well-posedness. An initial-boundary value problem is formulated. Existence and uniqueness of a positive weak solution is proved. Eventually, a comparison result is derived : the population of all regions decreases as the mortality rate increases in at least one region.
Aim The aims of this study were: (1) to identify global communities of tuna and billfish species ... more Aim The aims of this study were: (1) to identify global communities of tuna and billfish species through quantitative statistical analyses of global fisheries data; (2) to describe the spatial distribution, main environmental drivers and species composition of each community detected; and (3) to determine whether the spatial distribution of each community could be linked to the environmental conditions that affect lower trophic levels by comparing the partitions identified in this study with Longhurst's biogeochemical provinces.
Climate-induced changes in the physical, chemical, and biological environment are expected to inc... more Climate-induced changes in the physical, chemical, and biological environment are expected to increasingly stress marine ecosystems, with important consequences for fisheries exploitation. Here, we use the APECOSM-E numerical model (Apex Predator ECOSystem Model -Estimation) to evaluate the future impacts of climate change on the physiology, spatial distribution, and abundance of skipjack tuna, the worldwide most fished species of tropical tuna. The main novelties of our approach lie in the mechanistic link between environmental factors, metabolic rates, and behavioral responses and in the fully three dimensional representation of habitat and population abundance. Physical and biogeochemical fields used to force the model are provided by the last generation of the IPSL-CM5 Earth System Model run from 1990 to 2100 under a 'business-as-usual' scenario (RCP8.5). Our simulations show significant changes in the spatial distribution of skipjack tuna suitable habitat, as well as in their population abundance. The model projects deterioration of skipjack habitat in most tropical waters and an improvement of habitat at higher latitudes. The primary driver of habitat changes is ocean warming, followed by food density changes. Our projections show an increase of global skipjack biomass between 2010 and 2050 followed by a marked decrease between 2050 and 2095. Spawning rates are consistent with population trends, showing that spawning depends primarily on the adult biomass. On the other hand, growth rates display very smooth temporal changes, suggesting that the ability of skipjack to keep high metabolic rates in the changing environment is generally effective. Uncertainties related to our model spatial resolution, to the lack or simplification of key processes and to the climate forcings are discussed.
1] In recent decades, it has been found useful to partition the pelagic environment using the con... more 1] In recent decades, it has been found useful to partition the pelagic environment using the concept of biogeochemical provinces, or BGCPs, within each of which it is assumed that environmental conditions are distinguishable and unique at global scale. The boundaries between provinces respond to features of physical oceanography and, ideally, should follow seasonal and interannual changes in ocean dynamics. But this ideal has not been fulfilled except for small regions of the oceans. Moreover, BGCPs have been used only as static entities having boundaries that were originally established to compute global primary production. In the present study, a new statistical methodology based on non-parametric procedures is implemented to capture the environmental characteristics within 56 BGCPs. Four main environmental parameters (bathymetry, chlorophyll a concentration, surface temperature, and salinity) are used to infer the spatial distribution of each BGCP over 1997-2007. The resulting dynamic partition allows us to integrate changes in the distribution of BGCPs at seasonal and interannual timescales, and so introduces the possibility of detecting spatial shifts in environmental conditions.
There is an urgent need for developing policy-relevant future scenarios of biodiversity and ecosy... more There is an urgent need for developing policy-relevant future scenarios of biodiversity and ecosystem services. This paper is a milestone toward this aim focusing on open ocean fisheries. We develop five contrasting Oceanic System Pathways (OSPs), based on the existing five archetypal worlds of Shared Socioeconomic Pathways (SSPs) developed for climate change research (e.g., Nakicenovic et al., 2014 and Riahi et al., 2016). First, we specify the boundaries of the oceanic social-ecological system under focus. Second, the two major driving forces of oceanic social-ecological systems are identified in each of three domains, viz., economy, management and governance. For each OSP (OSP1 " sustainability first " , OSP2 " conventional trends " , OSP3 " dislocation " , OSP4 " global elite and inequality " , OSP5 " high tech and market "), a storyline is outlined describing the evolution of the driving forces with the corresponding SSP. Finally, we compare the different pathways of oceanic social-ecological systems by projecting them in the two-dimensional spaces defined by the driving forces, in each of the economy, management and governance domains. We expect that the OSPs will serve as a common basis for future model-based scenario studies in the context of the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES).
The basic components of an age-size and space-time structured statistical stock assessment model ... more The basic components of an age-size and space-time structured statistical stock assessment model are presented. The model could be flexible enough to capture some of the main population dynamics features observed in many tuna populations. The model could be applied to bigeye tuna (Thunnus obesus) data in the Atlantic Ocean. RÉSUMÉ Les éléments fondamentaux d=un modèle d=évaluation de stock structuré dans l=espace et dans le temps sont présentés ici. Le modèle pourrait être suffisamment flexible pour appréhender certains des aspects principaux de la dynamique des populations qui sont observés dans nombre de stocks de thon. Le modèle pourrait être appliqué aux données sur le thon obèse (Thunnus obesus) dans l=Atlantique. RESUMEN Se presentan los componentes básicos de un modelo de evaluación estadística del stock estructurado espacio-temporalmente y por edad-talla. El modelo puede ser lo suficientemente flexible para detectar algunos de los rasgos principales de dinámica de poblaciones observados en muchas poblaciones de túnidos. El modelo puede aplicarse a los datos de patudo (Thunnus obesus) del océano Atlántico.
The IOTC will soon implement a large tagging program in the Indian Ocean in order to obtain the p... more The IOTC will soon implement a large tagging program in the Indian Ocean in order to obtain the parameters needed to achieve reliable stock assessment for the target tropical tuna species, bigeye, yellowfin and skipjack. One of the first step of this work is the simulation of tag-recapture experiments. For that purpose, a habitat based tuna spatial dynamics model has
We develop an advection-difiusion size-structured flsh population dynamics model and apply it to ... more We develop an advection-difiusion size-structured flsh population dynamics model and apply it to simulate the skipjack tuna population in the Indian Ocean. The model is fully spatialized, and movements are parame- terized with oceanographical and biological data; thus it naturally reacts to environment changes. We flrst formulate an initial-boundary value problem and prove existence of a unique positive solution. We
The model PROCEAN (PROduction Catch-Effort Analysis) is a bayesian statistical catch/effort analy... more The model PROCEAN (PROduction Catch-Effort Analysis) is a bayesian statistical catch/effort analysis framework based on a generalized production model. The use of such a production model could be usefull in IOTC where reliable size data are missing for stock assessment. The aim of this paper is to present the PROCEAN model. PROCEAN is a multi-fleet non equilibrium generalized production model which includes process error for both catchability time series and carrying capacity of the stock. PROCEAN assumes that fluctuations of the stock surface may only have consequences on fleets catchability and on the stock carrying capacity. Our objective is not to propose a very realistic representation of the fishery. We propose a tool to extract the maximum amount of information from the data set by structuring it given a simple and well established theoretical model. Then, modeling is used here as a mean to explore data sets according to various hypothesis.
The IOTC initiated a discussion to organize a large scale tagging program concerning the major tr... more The IOTC initiated a discussion to organize a large scale tagging program concerning the major tropical tuna species and fisheries. According to the terms of reference for the working party on tagging (Anon., 1999), prospective simulations are needed to help designing tag-recapture experiments. The purpose of this paper is to present the methodology developed to help designing the future tagging
Bioaccumulation is difficult to document because responses differ among chemical compounds, with ... more Bioaccumulation is difficult to document because responses differ among chemical compounds, with environmental conditions, and physiological processes characteristic of each species. We use a mechanistic model, based on the Dynamic Energy Budget (DEB) theory, to take into account this complexity and study factors impacting accumulation of organic pollutants in fish through ontogeny. The bioaccumulation model proposed is a comprehensive approach that relates evolution of hake PCB contamination to physiological information about the fish, such as diet, metabolism, reserve and reproduction status. The species studied is the European hake (Merluccius merluccius, L. 1758). The model is applied to study the total concentration and the lipid normalised concentration of 4 PCB congeners in male and female hakes from the Gulf of Lions (NW Mediterranean sea) and the Bay of Biscay (NE Atlantic ocean). Outputs of the model compare consistently to measurements over the life span of fish. Simulation results clearly demonstrate the relative effects of food contamination, growth and reproduction on the PCB bioaccumulation in hake. The same species living in different habitats and exposed to different PCB prey concentrations exhibit marked difference in the body accumulation of PCBs. At the adult stage, female hakes have a lower PCB concentration compared to males for a given length. We successfully simulated these sex-specific PCB concentrations by considering two mechanisms: a higher energy allocation to growth for females and a transfer of PCBs from the female to its eggs when allocating lipids from reserve to eggs. Finally, by its mechanistic description of physiological processes, the model is relevant for other species and sets the stage for a mechanistic understanding of toxicity and ecological effects of organic contaminants in marine organisms.
This paper gives an overview of the ecosystem model APECOSM (Apex Predators ECOSystem Model) whic... more This paper gives an overview of the ecosystem model APECOSM (Apex Predators ECOSystem Model) which is developed in the framework of the GLOBEC-CLIOTOP Programme. APECOSM represents the flow of energy through the ecosystem with a size-resolved structure in both space and time. The uptake and use of energy for growth, maintenance and reproduction by the organisms are modelled according to the DEB (dynamic energy budget) theory and the size-structured nature of predation is explicit. The pelagic community is divided into epipelagic and mesopelagic groups, the latter being subdivided into vertically migrant and non-migrant species. The model is mass-conservative. Energy is provided as the basis of the model through primary production and transferred through 3D spatially explicit size-spectra. Focus species (tunas at present, but any predator species can be considered) are ''extracted" from the global size-spectra without losing mass balance and represented with more physiological and behavioural details. The forcing effects of temperature, currents, light, oxygen, primary production and fishing are explicitly taken into account.
The goal of this paper is to present a generic multi-region nonlinear age-size structured fish po... more The goal of this paper is to present a generic multi-region nonlinear age-size structured fish population model, and to assess its mathematical well-posedness. An initial-boundary value problem is formulated. Existence and uniqueness of a positive weak solution is proved. Eventually, a comparison result is derived : the population of all regions decreases as the mortality rate increases in at least one region.
Aim The aims of this study were: (1) to identify global communities of tuna and billfish species ... more Aim The aims of this study were: (1) to identify global communities of tuna and billfish species through quantitative statistical analyses of global fisheries data; (2) to describe the spatial distribution, main environmental drivers and species composition of each community detected; and (3) to determine whether the spatial distribution of each community could be linked to the environmental conditions that affect lower trophic levels by comparing the partitions identified in this study with Longhurst's biogeochemical provinces.
Climate-induced changes in the physical, chemical, and biological environment are expected to inc... more Climate-induced changes in the physical, chemical, and biological environment are expected to increasingly stress marine ecosystems, with important consequences for fisheries exploitation. Here, we use the APECOSM-E numerical model (Apex Predator ECOSystem Model -Estimation) to evaluate the future impacts of climate change on the physiology, spatial distribution, and abundance of skipjack tuna, the worldwide most fished species of tropical tuna. The main novelties of our approach lie in the mechanistic link between environmental factors, metabolic rates, and behavioral responses and in the fully three dimensional representation of habitat and population abundance. Physical and biogeochemical fields used to force the model are provided by the last generation of the IPSL-CM5 Earth System Model run from 1990 to 2100 under a 'business-as-usual' scenario (RCP8.5). Our simulations show significant changes in the spatial distribution of skipjack tuna suitable habitat, as well as in their population abundance. The model projects deterioration of skipjack habitat in most tropical waters and an improvement of habitat at higher latitudes. The primary driver of habitat changes is ocean warming, followed by food density changes. Our projections show an increase of global skipjack biomass between 2010 and 2050 followed by a marked decrease between 2050 and 2095. Spawning rates are consistent with population trends, showing that spawning depends primarily on the adult biomass. On the other hand, growth rates display very smooth temporal changes, suggesting that the ability of skipjack to keep high metabolic rates in the changing environment is generally effective. Uncertainties related to our model spatial resolution, to the lack or simplification of key processes and to the climate forcings are discussed.
1] In recent decades, it has been found useful to partition the pelagic environment using the con... more 1] In recent decades, it has been found useful to partition the pelagic environment using the concept of biogeochemical provinces, or BGCPs, within each of which it is assumed that environmental conditions are distinguishable and unique at global scale. The boundaries between provinces respond to features of physical oceanography and, ideally, should follow seasonal and interannual changes in ocean dynamics. But this ideal has not been fulfilled except for small regions of the oceans. Moreover, BGCPs have been used only as static entities having boundaries that were originally established to compute global primary production. In the present study, a new statistical methodology based on non-parametric procedures is implemented to capture the environmental characteristics within 56 BGCPs. Four main environmental parameters (bathymetry, chlorophyll a concentration, surface temperature, and salinity) are used to infer the spatial distribution of each BGCP over 1997-2007. The resulting dynamic partition allows us to integrate changes in the distribution of BGCPs at seasonal and interannual timescales, and so introduces the possibility of detecting spatial shifts in environmental conditions.
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Papers by Olivier Maury