This project seeks to design and construct a BIOacoustic Sensing Platform And Relay system (BIOSPAR). This is an autonomous dual beam acoustic profiler that will automatically measure and telemeter biologically produced acoustic backscattering and target strength data from remote oceanic locations to shore based laboratories. The down-looking system, with 420 and 120 kHz dual- beam echo sounders, will be packaged first for autonomous deployment in a spar buoy and coupled to a satellite telemetry system. Profiles of acoustic backscattering by range gating returns into 1 meter depth intervals in the upper 100 meters will be obtained. All data will be stored on a mass storage unit in the buoy for post processing. Partially processed data in the form of a target strength histogram and integrated intensity for 10 depth intervals at each frequency will be averaged over 2 hour intervals for daily transmission to shore. The system will be tested at sea and used on a research cruise in 1990 to study variations in the abundance and size-frequency distribution, and diel migration of plankton and nekton in a Gulf Stream ring. The field tests will involve the use of a towed net system to collect zooplankton and micronekton for comparion with acoustic data. Designs for alternate deployment modes (bottom landers, deep-sea moorings) will also be planned. This instrument offers the potential to revolutionize our ability to obtain information about the distrubution and interactions of important oceanic plankton and neckton over periods of time. Such data is now extremely complex and costly to obtain.