Authorities around Japan's largest lake have launched a "catch-and-eat" drive to eliminate the bluegill as the emperor himself voiced regret about introducing the fish. Emperor Akihito, a fish expert, brought the bluegill from the United States a half-century ago when he was crown prince, hoping to offer a new source of food to Japan.But the bluegill, once celebrated as "prince fish," has turned into a nuisance in Japanese rivers and lakes by feeding on native species, leading the emperor to offer unusually personal comments of regret earlier this month.The central province of Shiga has introduced what it calls "catch-and-eat," encouraging people who fish bluegill in Japan's largest Lake Biwa not to release but to eat them.The prefecture's official website has pictures showing how to slice open the fish along with recipes to make bluegill fries and cook them with sweet-and-sour sauce."The fish taste very good," Shiga fisheries official Kunihiko Kuwamura said, adding there was also "bluegill sushi" offered by a private company.Bluegill is common dinner fare in the United States and is the state fish of Illinois, where Chicago's legendary mayor Richard J. Daley offered the fish specimen as a gift to the visiting Akihito in 1960.Akihito voiced regret in a speech at a fisheries event on November 11, saying Lake Biwa's catch had plunged due to foreign-origin fish."I brought bluegill back from the United States nearly 50 years ago and donated them to a research institute of the Fisheries Agency," said Akihito, whose public remarks are usually ceremonial."Its cultivation started as there were great expectations of raising them for food in those days. My heart aches to see it has turned out like this," Akihito said.The Fisheries Agency says its research institute received the fish in 1960 and bred and distributed them around the country.Shiga prefecture denies bluegill escaped its institute's nets. They were first spotted swimming in Lake Biwa in 1965, according to Kuwamura.Kuwamura said the prefecture has tried for years to get rid of foreign-origin fish and that the emperor's remark "is a boon for us.""We will keep pushing ahead," he said.