The Acoustic Measurement of Plankton Population Density

Measurement of the density of populations of particles or organisms in suspension in a fluid has been a matter of interest for some years. This paper outlines some of the underlying principles involved in using acoustic backscatter and gated, echo-squared integration to perform such measurements, It presents the Gamma distribution as the statistical descriptor for the integrator output. It then describes the design of a broad-band, high-frequency sonar devised for the estimation, particularly, of plankton population density. Experiments used to assess performance are outlined, and results are presented which confirm the theoretical distribution of echo-squared integrator output.