Evaluation of Fish Farm Environments by Identifying Community Types of the Macrobenthos

Abstract

In order to evaluate the fish farm environments, a quantitative survey of the macrobenthos was conducted in 22 fish farms along the coast of Kumano-nada, middle Japan. Six macrobenthic communities were recognized by cluster analysis. These communities were classified into three groups in the gradients of fish production and an index “ED”, which was defined in the previous report to indicate the topographic conditions of the sampling site. These groups consisted of a group with high density and high diversity, a group characterized by an impoverished fauna and an azoic site group, which indicated conditions as healthy, cautionary and critical, respectively. As fish production increased, habitat of the assemblage at the cautionary zone shifted to the offshore, deeper areas with smaller ED values, suggesting the influence of aquacultural activities on the macrobenthos. We can evaluate environmental conditions of the fish farm by identifying community types of the macrobenthos that may lead us to decide the appropriate location of the farm and the proper fish production for sustainable aquaculture.