Studying the Ocean Planet requires measuring and sampling instruments to feed models that take into account its complexity.  This book presents the diversity of observation and monitoring techniques at various scales, but also different kinds of model that take into account some conceptual schemes incorporating various scientific knowledge. Sampling is approached via the efficiency of fishing gears; underwater acoustics is used to detect, count, identify and listen to live and mobile living resources. Bio-logging allows us to rely on the behavior of marine animals to help investigate environments that are difficult to sample by conventional means, while listing the physiological changes they undergo. Modeling is presented not only in a functional framework, but also in an exploratory design incorporating various scenarios for ecosystem changes under the pressure of global change. This ninth volume completes the “Seas and Oceans� Set that adopts a transversal approach leading to the governance and sustainable management of the marine environment.