Abstract
A fishery simulator is developed for a bottom otter trawling in Ise Bay, which consists of fish
behavioural models for major two species and a fishing operation model. The fish behavioural models
simulate resource conditions for two major target species, conger eel and mantis shrimp, considering the
fish migration as well as the growth and the population change. The fishing operation model predicts the
behaviour of trawling boats based on economic conditions and resource distribution to calculate the fish
catch amount by each boat. The developed simulator well reproduced annual variations of CPUE （catch
per unit effort） for conger eel and mantis shrimp. It was indicated that precise environmental conditions
should be used to predict behaviour of boats accurately. The simulator was also applied to assess the
effects of variables within fishery management such as the control of mesh size for trawling nets, the
release of small fish, and introduction of facility to keep caught fish alive. The mesh size of trawl net
which maximize the fish catch will be different for each fish species. To release larger fish will be
effective only for conger eel because of the high mortality rate of released mantis shrimp. The
introduction of an on-deck shower device for caught fish will be cost effective as well as easy to reach
consensus upon.
