Assessment of the Effect of Artificial Reef on Fish Distribution: The Combined Use of Acoustic Data and GIS

Abstract

Artificial reefs have been constructed in numerous coastal areas off Japan to enhance coastal fisheries. The setting up of a method to assess the effectiveness of these artificial reefs is essential for controlling and managing these projects. The distribution of fish schools around reefs is frequently characterized by significant variability with respect to time and space dependent on the environmental conditions. This study aims to find methods that provide a better understanding of the spatial distribution of fish schools around reefs. The pilot study area was located in the Japan Sea off Nagato, Yamaguchi Prefecture. A survey methodology was developed that combines the acoustic method and Geographic Information System (GIS) techniques. These GIS techniques were used to demonstrate the distribution of schools on the two- and three-dimensional map. Hydroacoustic and oceanographic observations were conducted from 1996 to 2001, and 1 year of data on fish distributions and oceanographic conditions in the reef area were collected to assess the effects of artificial reefs. The relationship between the spatial distribution of fish schools and environmental factors, including the bottom topography, was assessed in visual form using GIS techniques. These results show the effectiveness of the combined use of GIS and the acoustic method to assess the distribution of fish schools around artificial reefs.