Studying Dvm Using Stationary, Submerged Echosounders Cabled to Shore

There is a long history of using echosounders from moving vessels in population studies of Diel Vertical Migrations (DVM). Stationary echosounders additionally facilitate studies of individuals, since individual organisms may be followed over many “pings” in a non-moving acoustic beam. Submerged echosounders provide superior resolution of individuals in deep waters. And systems cabled to shore provide continuous observations which can unveil short-term, seasonal and yearly variations in migration patterns. In this talk we show how stationary, submerged echosounders cabled to shore may be used to unveil information on DVM behavior among individuals as well as populations of both plankton and fish. Results for a variety of taxa show that populations may split into different groups that simultaneously exhibit deviating migration behavior. Behavioral repertoirs unveiled in this way comprise no DVM, asynchronous DVM, inverse DVM, and (varieties of) normal DVM, the relative prevalence of these behaviors often varying over time within the same population.