Changes in Fishery Resources in Relation to Water Environments in Osaka Bay

Abstract

An attempt was made to analyze the relationship between the change in the quantity of fishery resources and the change of phosphorus load deposited into Osaka Bay. The phosphorus load had steadily increased from 1955 to 1975, then decreased slowly towards the 2000s. The major benthic fishery organisms, such as octopus, shrimp and crab, mantis shrimp, tongue-fish and right-eye flounder, were employed to examine the characteristics of change in fishery resources in relation to water environments of Osaka Bay. Excluding shrimp and crab, catch amounts showed a largely equivalent response to phosphorus load in the bay. The results presented here demonstrate that a close relationship exists between phosphorus emissions and benthic fishery resources in Osaka Bay.