Date of Completion


Embargo Period



Laura Kracker; Walter F. Bohlen

Field of Study

Materials Science


Master of Science

Open Access

Open Access


Predator-prey interactions of large vagile fishes are difficult to study in the ocean due to limitations in the space and time requirements for observations. Small-scale direct underwater observations by divers (<10m >radius) and large-scale hydroacoustic surveys (10s - 100s km2) are traditional approaches. However, large piscivorous predators identify and attack prey at the scale of meters to tens of meters. Dual- Frequency Identification Sonar, or DIDSON, is a high-resolution acoustic camera operating in the MHz range that provides detailed continuous video-like imaging of objects out to 30 m range. This technology can be used to observe predator-prey interactions at ecologically relevant space and time scales often missed by traditional methods. Here I establish an approach for quantifying predation related behaviors from DIDSON records. Metrics related to predator and prey group size, prey responses to predation, predation rate, predator strategies, and the non-random use of landscape features by both predator and prey are described, relationships between patterns in these attributes are tested, and issues regarding sampling strategies for future studies are discussed. Approaches combining direct visual observation and acoustic sampling at multiple scales are required to gain a greater understanding of variation in such relationships across underwater landscapes and the role such relationships play in the demographics of fish populations and communities.

Major Advisor

Peter J. Auster