INFLUENCE OF BENTHIC INVERTEBRATE ABUNDANCE ON THE STOCK OF JAPANESE EEL IN TWO COASTAL STREAMS

Abstract

 Japanese eel is now endangered, and there is an emergent need for accumulating ecological knowledge during its riverine life. This study aimed to elucidate the influence of benthic invertebrate abundance (i.e. food availability) on the stock of Japanese eel based on quantitative surveys conducted in two coastal streams in Ehime Prefecture, southwestern Japan. As a result, eel abundance was shown to be high at study sites with high invertebrate abundance. This result suggests that conserving food resource can be an effective option for the conservation of Japanese eel. However, since this relationship differed depending on the rivers and seemed to be confounded with other physical factors, we suggest that extensive survey and analysis is required for disentangling the causal relationships among factors affecting eel stock and for better conservation planning.