Visualizing fish movement, behavior, and acoustic backscatter

Abstract

Acoustic surveys of aquatic organisms are notorious for large data sets. Density distribution results from these surveys are traditionally graphed as two-dimensional plots. Increasing information content through wider acoustic frequency ranges or multiple angular perspectives has increased the amount and complexity of acoustic data. As humans are visually oriented, our ability to assimilate and understand information is limited until it is displayed. Computer visualization has extended acoustic data presentation beyond two dimensions but an ongoing challenge is to coherently summarize complex data. Our goal is to develop visualizations that portray frequency- and behavior-dependent backscatter of individual fish within aggregations. Incorporating individual fish behavior illustrates group dynamics and provides insight on the resulting acoustic backscatter. Object-oriented applications are used to visualize fish bodies and swimbladders, predicted Kirchhoff-ray mode (KRM) backscatter amplitudes, and fish swimming trajectories in three spatial dimensions over time. Through the visualization of empirical and simulated data, our goal is to understand how fish anatomy and behavior influence acoustic backscatter and to incorporate this information in acoustic data analyses.