Comparison of feeding conditions in adult marbled rockfish Sebastiscus marmoratus between an inclined sea wall of Kansai International Airport and a natural rocky shore

Abstract

In order to evaluate the capacity of the inclined sea wall of Kansai International Airport island as a nursery ground of marine organisms, we examined feeding conditions of adult marbled rockfish Sebastiscus marmoratus caught from a rubble mound type inclined sea wall of the airport and a natural rocky shore near the southern mouth of Osaka Bay. We also compared fauna and abundance of macrobenthos between the two habitats. Sebastiscus marmoratus caught from the sea wall took less food than those from the natural shore. Amphipods accounted for a high percentage of its food items instead of decapods, which are ordinarily the principal food organisms of adult S. marmoratus. On the other hand, the fauna, weight, and number of macrobenthos on the sea wall were generally less than those on the natural shore. Particularly, the number of decapods was about one third of that on the natural shore. These facts indicated that there is a shortage of the food preferred by S. marmoratus on the sea wall of Kansai Airport. We also discuss the relationship between these feeding conditions and the shape of the sea wall of the airport.