Dataset: shrimp acoustic survey locations

This project attempted to test whether an acoustic component could be successfully added to the annual summer survey for Northern Shrimp, Pandalus borealis. The summer shrimp survey consists of 15-minute bottom trawl tows conducted in a stratified, random design with station density per stratum weighted by the historical presence of shrimp. Relying on a trawl survey means only a small portion of the total bottom is surveyed, due to time constraints and limited areas where a net can be towed. Additionally, it is impossible to know whether a high-catch tow represents a tow that passed through the center of a medium sized school, or one that passed through the edge of a much larger school. Acoustic survey techniques are generally not hampered by rough, untowable bottom and have the potential to cover areas more rapidly and completely than an equal amount of effort spent conducting trawl surveys. The participants hoped to demonstrate whether acoustics could be used to inform the results of the tow samples and to conduct surveys in areas that cannot be assessed using a bottom trawl. Despite carrying out operations in areas where shrimp were know to be present and using frequencies other groups have used successfully to detect Pandalus borealis, shrimp schools were never recorded by the 40, 75 or 120 kHz equipment used in this project. While other equipment and techniques (different frequencies and multibeam systems for example) might be effective in detecting and discriminating shrimp, results from this project indicate the tools and techniques tested in this study were not suited to assessing shrimp in the Gulf of Maine.