Acoustic Doppler Current Profilers (ADCPs) are now used routinely by physical oceanographers. A by-product of the signal processing for calculating the Doppler shift used to determine current velocity is the intensity of the acoustic backscatter, and this, in turn, is a measure of biomass. ADCPs can therefore potentially provide biological oceanographers with quantitative in- formation, collected routinely and non-intrusively in near real time. If these acoustic measurements are ob- tained concurrently with hydrographic data, the possibil- ity of collecting quantitative biological information on the same time and space scales as physicochemical data becomes a reality. ADCPs have been routinely operated on NERC ships for several years. Examples of the types of biological information which can be obtained are de- scribed here in the hope that this will stimulate other users to make use of a potentially valuable source of data.