Abudance estimation by automatic analysis of marine species from underwater optical records, Post.dr.

In August 2002 successful video records were taken at the trawl opening at 500-600 m depth west of Spitzbergen. Very clear records of fish individuals and stable camera conditions were obtained. Simultaneous detection of fish and its bottom shadow enables a 3D detection of fish position. Thus fish length and behaviour such as 3D velocity can be calculated. In addition, the spatial distribution of the species can be determined based on succeeding detection times of each individual. A major goal of the proj ect is to develop methodology and algorithms for efficient automatic detection and analysis of marine species from trawl video records and other optical records like flash photos. The potential for improved estimates of accuracy and precision of abundance estimates will be outlined. One option is to sweep much larger areas with open trawl end, or other rigs, at the same cost as traditional techniques. Increased knowledge of behaviour, catchability, spatial distribution and trawl behaviour may also greatly improve precision and accuracy estimates of historical abundance estimates.