Mesopelagic fish constitute the most abundant vertebrate group in the marine environment. They are small species inhabiting the mesopelagic zone (100-1000 m), while several species perform Diel Vertical Migrations (DVM). Together with other organisms they form Deep Scattering Layers (DSL) detected by echosounders. Mesopelagic fish constitute a link between zooplankton and apex predators, they contribute to benthic/pelagic coupling and to the “biological pump” and are responsible for a large fraction of the carbon fluxes in the oceans. Despite these, research on mesopelagic fish is still at a relatively early stage. However, recent findings have triggered an increased interest on their biology, population ecology, abundance, distribution and ecological role.
MesoBED, will explore the distribution, biological aspects and the ecological role of mesopelagic fish in the Greek seas. The project includes the application of the acoustic methodology during research cruises in selected study areas of the Aegean and Ionian Seas aiming to shed light on the properties and species composition of the DSL, to study the horizontal and vertical distribution of mesopelagic fish in relation to environmental factors and to derive density estimates of the DSL. In addition, the project will study the biology of mesopelagic fish populations, including aspects of reproductive strategies (e.g., sex ratio, maturity, fecundity), length-weight relationships, age and growth. Finally, their feeding habits will be studied and along with (i) a review of their use as a prey by predators, (ii) the biomass estimates and (iii) biological parameters, will be used to parameterise an ecosystem model in order to explore the ecological role of mesopelagic. Overall, MesoBED aims to advance knowledge on mesopelagic fish and the pelagic environment in general, to advance the application of Ecosystem Approach to Fisheries in the Mediterranean Sea as well as to set the basis for future research on this topic.