Emperor distressed after introducing fish to Japan

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The Emperor of Japan has expressed contrition over the his role in introducing the Bluegill sunfish into Japan, where it is now threatening native fishes.

Speaking at a national convention on fisheries and conservation in the city of Otsu, Emperor Akihito told Yomiuri Shimbun "I myself brought some Bluegills (Lepomis macrochirus) back from the United States about 50 years ago.

I donated them to a research body of the Fisheries Agency. Initially, there were high expectations of the fish being used as a food source. Farming of the fish started soon afterward.

However, seeing the resulting situation now makes me feel deeply distressed."

The bluegills were given to the Emperor (who is a keen ichthyologist) by the mayor of Chicago when he visited the city in 1960 as the Crown Prince.

The donated fish were cultured and bred by the Fisheries Agency, who gave 1400 of them to the Shiga Prefectural government in 1963"64 for further culture in Lake Biwa (the largest lake in Japan).

The fish has subsequently gone on a rampage in the lake, with the number peaking at about 50 million in 2002. The number has since been halved thanks to an extermination campaign.

Although efforts were made to promote the bluegill as a desirable food fish, the idea never really caught on. Officials at Lake Biwa now regularly catch bluegills to for use as fertilizer or chicken feed. A decline in the fisheries of Crucian carp (Carassius carassius) in Lake Biwa is attributable to the introduction of the Bluegill.

Together with other introduced fish species such as the Largemouth bass (Micropterus salmoides), the Bluegills are said to be responsible for driving the native Rosy bitterling (Rhodeus ocellatus) close to extinction and threatening other native species.