Three-dimensional Visualization of Fisheries Acoustics Data and Models

J. Michael Jech and David F. Chevrier
Northeast Fisheries Science Center, NMFS

Fisheries acoustics methods are an efficient and effective approach for providing fisheries-independent estimates of densities and abundances of commercially important fish stocks. Acoustical data collected during fisheries surveys provide continuous coverage of the entire water column along the cruise track. Concurrent biological sampling from net hauls and underwater video systems allow verification of the sources of acoustical echoes.

Typically the acoustical data are displayed as two-dimensional 'echograms' - vertical dimension through the water column, and time along the horizontal axis. Traditional echograms are not suitable for viewing the data in a geographical context. We have developed three-dimensional visualizations of multi-frequency acoustical survey data to view the data in geographical space from small to large spatial scales. Acoustical data are commonly used to provide relative indices of species-specific abundance and biomass. In order to scale the relative indices to absolute estimates, we must incorporate a measure of the echo amplitude from an individual fish. Fish are complicated acoustical scatterers by nature of their complex anatomy and behavior. We have developed three-dimensional visualizations of the fish body and swimbladder from x-ray and Computed Tomography (CT) images. These images are used in theoretical models to improve prediction of acoustical scattering over a wide range of frequencies and fish orientations. We will present three-dimensional visualizations of acoustical survey data, internal anatomy of selected fish species, and predicted acoustical backscatter, and will discuss the utility and implications of 3D visualizations in fisheries management.