Spatial and Temporal Variation of the Fish Assemblage on a Large Artificial Reef Assessed Using Multiple-Point Stationary Observations

Abstract

Over the past decade, the sizes of artificial reefs in Japan haveincreased, with heights reaching 30 m or more. However, there are fewstudies about the efficiency of the high-rise artificial reefs, and itis not clear how effectively these reefs gather and nurse fishresources. In these large artificial reefs, it is difficult for diversto view entire schools of fish. We developed a stationary observationsystem called FISCHOM (fish school monitoring system) to replace orcomplement visual censuses conducted by divers. FISCHOM consists of astereo camera, a programmable timer, and a battery in a stainless steelpressure-resistant housing with transparent acrylic glass rated to adepth of 80 m. FISCHOM takes periodic underwater stereo images, and itsmaximum duration of operation is approximately 2 months when thephotographing interval is set to 1 h. By using multiple FISCHOM systemsaround an artificial reef, researchers can obtain quantitative data onfauna and body size compositions of the reef fish assemblages and theirtrends. In this study, we will try to describe the possibilities offeredby FISCHOM to study the artificial reef fish assemblages. Then, we willshow the survey results conducted at a high-rise artificial reef in theSea of Japan. We describe the advantages and limitations of FISCHOM forobserving artificial reef fish assemblages based on the results of thesurvey.