AFSC/RACE/MACE: CamTrawl transition to operations

CamTrawl is a fisheries survey device that enables species and size composition data to be collected from within a midwater survey trawl using stereo cameras. This data obtained from images can be used to partially replace or supplement traditional trawl sampling, which involves capturing live fish, and sampling them on the survey vessel. Image­based sampling using CamTrawl allows for distinct periods during trawl sampling to be independently identified and analyzed, thereby increasing the spatial resolution of sampling and enabling independent assessment of discrete fish schools separated horizontally or vertically in the water column.

This sampling method can also sample without extracting fish from the environment, enabling longer tow times in highly dense fish schools without concerns of overwhelming the capacity of the trawl. Finally, without the need to handle the catch, the workload for survey personnel is greatly reduced, making it possible to reduce the number of crew and overall survey costs.

Primary purpose for this project is to transition of CamTrawl into operations, such that it becomes a standard survey device requiring little intervention from technical staff to operate and maintain, and providing consistent and timely data for direct integration into survey products. Specific components for making the system operational include standardized deployment methods, data handling and storage, and standardized and repeatable analysis procedures. Of these elements, for this task the focus is on analysis. This basically involves applying automated image processing routines to extract size and species composition information, which is then uploaded into a production catch database and can be accessed for all other aspects of survey analysis, including abundance estimation. The basic unit of data consists of a stereo ­image pair, which with the aid of stereo calibration parameters can be used to range objects seen in the images and therefore extract accurate length estimates for fish at different distances and orientations from the camera. Data extracted from Camtrawl include target length (in cm), classification (species or species group), time imaged, and depth of camtrawl unit at imaging. When inserted into the catch database, it is assigned a unique specimen id as well.