Fisheries Acoustics Research - Introduction Introduction Fisheries acoustics uses sound to detect, map, and count distributions of aquatic organisms. Accurate conversion of acoustic data to estimates of animal size or population abundance requires an understanding of the scattering properties of fish and invertebrates. Animals in the water are complicated scatterers of sound due to their shape, composition, curvature, and behavior. To study these scattering properties we use anatomically-based, numeric models to quantify the relative importance of biological and physical factors that influence the amount of sound backscattered from aquatic organisms. This is important when estimating abundance or discriminating targets because interpretation of data is influenced by the amplitude and variability of backscattered sound.
Fish come in all shapes and sizes.
The amount of sound that a fish reflects largely depends on whether it has a swimbladder, its size, its orientation to the sound source, and what frequency you are using to view the fish. The dark colored organ in the radiograph is the swimbladder. Most of the returned sound from a fish is reflected by the swimbladder. Check out our radiograph gallery to see a collection of fish x-ray images. To quantify variance in backscatter amplitudes we compare model predictions of individual or aggregations of fish to measurements from tethered fish or research survey data.