Research.Marine ecosystems provide essential services to humans. For instance, they contribute to the regulation of climate through the biological carbon pump; they are also an important source of food. A challenge is to determine how the biomass produced at a low trophic level influences the harvestable biomass supporting fisheries, and vice versa, how the harvested biomass controls the production at lower trophic levels, both in the context of a changing climate and increasing food demand. To tackle these challenges, I use and develop marine ecosystem models (APECOSM, BOATS) that I compare and merge with data sets that describe the ecology (Fishbase, Acoustic transects), fishing (RAM Legacy, Sea Around Us Project, Global Fishing Watch), at the regional to global scale.
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Modeling the biomass flow in the California Current
Fish abundance and spatio-temporal distribution depend on prey distribution, water temperature, oxygen availability, and biomass distribution by currents. To parse the relative contribution of these distinct drivers, we implement a regional model of the biomass flow in the California Currents based on elementary size-dependent processes and the effect of the environment on them. The model, APECOSM-CC, forced with a realistic physics and biogeochemistry model, ROMS-BEC, reproduces the spatio-temporal pelagic fish dynamics between 1mm and 2m. This regional simulation, the first of its kind, is a tool to test how mesoscale dynamics influence this fish biomass distribution. |
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Reconstruction of fish biomass distribution from acoustics
Mid-trophic level fish are prey for larger predators; they are a key component of marine food-webs. To identify the spatio-temporal dynamics of mid-trophic level biomass in the California Current and the effect of the environment on it, we study EK60 acoustic transects from scientific cruises. A synoptic view of this fish biomass distribution is critically missing; it notably impairs the development and tuning of marine ecosystem models. Merging multi-frequency acoustic analysis with remote sensing observation through neural network methods, we aim to build this synoptic view. |
Bio-economical coupling of fish communities with fisheries
Fisheries yields are both influenced by fishing efforts and the productivity of fish stocks. The productivity of stocks depends on food-webs structure; it is also influenced by ecosystems' productivity and water temperature that affects fish metabolism. We use the ecosystem model BOATS to test the linkage between environmental conditions and global fishing yields. It is applied to study the influence of fishing on fisheries' past development and predict future fishing yields in a warming ocean. |