Sammendrag
IMR (Norway) tested the Deep Vision in-trawl stereo camera system during part of the 2021 IESSNS. The system was tested both in five surface trawl hauls, with comparative hauls without Deep Vision at the same survey stations, and in five deep hauls without comparative hauls. Results indicated the camera system did not affect the trawl’s geometry and there are indications that catch rates were in fact higher with the Deep Vision system in the trawl (result just statistically significant). A RetinaNet neural network did a good job of differentiating between Atlantic mackerel; Atlantic herring and blue whiting, with good correspondence to species percentages measured from the catches. Absolute counts are less accurate due to double-counting the same individual in consecutive images and difficulty detecting all individuals when the density of fish passing the camera was extremely high. Counts can likely be improved by training the network with more high-density images. Work to automate measurements of length from images is in very early stages. The Deep Vision system will not be used during the 2022 IESSNS, but will be implemented during the Norwegian portion of the 2022 IESNS.
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