To clarify the difference of fish species attraction to artificial fish reefs according to the structure of fish reef units, fish catch experiments were performed at different reef units and a control area arranged in Furubira-cho offing, Hokkaido. The attraction effect of the fish reefs for each fish species due to differences in structure was ascertained by use of principal component analysis (PCA). As a result, accumulated contribution ratio of the directivity for the element of fish reef unit accounted for 89% and the main characteristics were explained by just four components. It was suggested that the characteristics of the attraction effect for each fish species were different among the types of the fish reefs.
