As fishing gear consists mainly of netting and rope, and lacks a definite geometry of its own, external forces acting on the netting and other rigging determine its geometry. The underwater geometries and loads of most fishing gear cannot be grasped in detail. However, the versatile simulation technique that we have developed for fishing gear allows us to understand the physical properties of dynamic fishing gear underwater. This will allow companies to design optimal fishing gear, based on scientific research and avoiding empirical procedures. In addition, it will allow fishermen to evaluate and improve their standard operating techniques, and to develop optimal techniques. The calculation model assumes that the net consists of lumped point masses that are interconnected by mass-less springs. The equations of motion of these point masses can be expressed in a local coordinate system, which simplifies the treatment of the hydrodynamic forces acting on each mass using the inertia transformation algorithm. The computer simulation not only estimates the overall shape of fishing gear but also its mesh geometry, the tension on the netting, and the impact force on the sea bed. This will allow the development of smart gear and smart fishing. Users will be able to develop and operate fishing and aquaculture gear based on a sound understanding of the physical parameters, and design gear that is economical, efficient to operate, and less harmful to the ecosystem. In this paper, we introduce the net geometry simulation system (NaLA) and discuss how to apply the system to developing smart gear and smart fishing.

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