Development of GIS using acoustic measurement methods for quick quantitative assessment of marine bioresources

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This study aimed to develop quick assessment methods of aquatic living resources using Geographical Information System (GIS). We measured mesopelagic fishes and seagrass/seaweed beds, which haven't investigated, with quantitative echosounders and acoustic measurement instruments. We quantified alfonsin (Beryx splendens), one of the most important mesopelagic commercial fish around seamounts in Japanese exclusive economic zone by using a split-beam echosounder. We mapped precise bottom topography of seamounts with multibeam sonar and differential-GPS. These data were incorporated into the system that can quickly assess the relation between quantitative fish distribution and bottom topography using GIS. We also developed the system that can show substrate including seagrass scanned by echosounder on the display of portable personal computer in real time. The developed software processes signals from the echosounder and D-GPS and classify substrate localizing ship position with GPS. We made field surveys on seagrass and seaweed beds in Sanriku Coast, in Miura Peninsula of Kanagawa Prefecture and Posidonia beds in Mediterranean Sea. Sea truth was also done in these areas. In Sanriku Coast, we studied ecology and biomass of Zostera caulescens. In addition, we made analysis with GIS on change in intertidal ecosystem polluted by Nakhodka oil spill accident and management of coastal area as studies using GIS applied to fisheries science and fisheries oceanography. Acoustic survey has needed highly specialized knowledge for use and produced large quantity of data. Therefore acoustic survey has been very complicated method to estimate resources. Acoustic survey is recommended to estimate fisheries resources because it is independent from the fisheries activity. Our study succeeded to develop easy quick assessment methods integrating GIS and acoustic survey data. We plane to develop another quick assessment methods for other marine bioresosauces with variety of life forms.