AUTHOR=Hill Cruz Mariana , Kriest Iris , Getzlaff Julia 

TITLE=Diving deeper: Mesopelagic fish biomass estimates comparison using two different models

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1121569

DOI=10.3389/fmars.2023.1121569

ISSN=2296-7745

ABSTRACT=A growing population on a planet with limited resources demands finding new sources of protein. Hence, fisheries are turning their perspectives towards mesopelagic fish, which have, so far, remained relatively unexploited and poorly studied. Large uncertainties are associated with regards to their biomass, turn-over rates, susceptibility to environmental forcing and ecological and biogeochemical role. Models are useful to disentangle sources of uncertainties and to understand the impact of different processes on the biomass. In this study, we employed two food-web models -- OSMOSE and the model by Anderson et al. (2019, or A2019) -- coupled to a regional physical--biogeochemical model to simulate mesopelagic fish in the Eastern Tropical South Pacific ocean. The model by A2019 provides a larger biomass of mesopelagic fish compared to OSMOSE. The temporal variability in OSMOSE is affected by an explicit life cycle and food web. The model by A2019 is more convenient to perform uncertainty analysis and it can be easily coupled to a biogeochemical model to estimate mesopelagic fish biomass. OSMOSE is convenient to understand the interactions of the ecosystem and how including different life stages affects the model response. The combined strengths of both models allows to study mesopelagic fish from a holistic perspective, taking into account energy fluxes and biomass uncertainties based on primary production, as well as complex ecological interactions.