抄録
Laboratory experiments and field surveys in a set net were conducted by use of the acoustic camera,
DIDSON, as a device to observe behaviours of various fish species without an influence on them. As a
result of laboratory experiments, it was shown that a frame rate of images taken by DIDSON peaked out
when an observation distance was shorter than 5m, while the resolution of subject improved in
proportion to a shortening of an observation distance and a frame rate improved in inverse proportion to
it when a distance was longer than 5m. This may cause an image deformation of the moving subject at a
shorter observation distance because DIDSON draws it by the interlace scan. As a result of observations
in the set net under the optimized setting of DIDSON taking above results into consideration, it was
possible to discriminate images of bluefin tuna from other species.
