The present report aims to show an example of the applicability of the GIS (Geographic Information System) in marine science, as the preliminary step to assess the influence of environmental factors on the distribution of fish around artificial reefs, using the data collected from the model area, in which 8 large-scaled artificial reef clusters were constructed. One of the most effective functions of this new technique for the present purpose is to make it possible to understand easily and clearly the spatial distribution of fish and factors which probably have the relation to it, in clear visual form. From the illustration (Figs.5 & 6), many important information could be extracted. They were apt to be not taken into account, in spite of the fact that they sometimes have decisive influence on the planning of further steps of data analysis. The detailed information extracted are shown in the present report.
1. INTRODUCTION
Establishment of the method of assessing the influence of various factors on the coastal fisheries is the matter of urgent necessity for controlling and managing them.
A number of artificial reefs have been constructed along the coastal area of Japan for the enhancement of coastal fisheries.1,2) In spite of this fact, there were few papers describing the spatial distribution of the resources in relation to the environmental variables. because it has been difficult to collect time-and-space depending change of fisheries data and to visualize and quantify their relation to oceanographic and environmental conditions. The acoustic data are the most practical ones capable of being collected in real time base at high economic/effort efficiency. to express the distribution of fish.3) It is natural that the relaion of the obtained results to the following environmental conditions should be examined: the water temperature, salinity, contents of dissolved oxygen (DO) and bottom topography.
Geographic Information System (GIS) techniques, which are widely used in processing satellite imagerys,4) was adopted in the present report to develop a new tactics as the preliminary step to assess the influence of artificial reefs on the coastal fisheries using acoustic data, because fisheries acoustic data have nature similar to land use data and satellite imagery.5)
The present report aims to show the applicability and effectiveness of the method newly expanded its use into marine science.
2. MATERIALS AND METHODS
2.1 Positions of artificial reef clusters
In the present study, the area off Nagato along the Japan Sea coast of Yamaguchi prefecture (Fig.1), in which many large-scaled artificial reef clusters were
