Construction of a remotely operated catamaran with acoustic system for observations of fish response to bottom trawls

A remotely operated catamaran (ROC) was constructed with the goal of accessing the area behind a trawling vessel, but in front of the trawl net, to observe fish behavior in this unique and otherwise difficult to access area. This report focuses on the technical components used to construct the ROC. Once constructed, the ROC was towed behind a trawling vessel and remotely steered in order to acoustically image all locations between the vessel and the front of the trawl net. The data gathered by the ROC and equivalent vessel-mounted acoustic systems were used to compare fish vertical distribution and density directly under the survey vessel and in front of the bottom trawl.