Abstract
Surveys were carried out at several set-net fishing grounds using a scanning sonar to study the appearance times of each species. Flying fish and salmon were observed in the daytime, while mackerel, sardine and other species during the night and day. Their appearance times were different depending on the species. Set-nets were in operation for 24 hours in order to catch all the different species of fish.
The movement behaviour of the spotted mackerel and salmon were also analyzed using the fish number and distribution data that had been gathered from the area under observation. Their movement to and from the coast was caused by their repeated movement behaviour around the set-nets. These movement behaviour patterns were regarded as being attributed to the passive capturing process of the set-nets in relation to diurnal periodicity.
