He introduced the bluegill into Japan considering the serious food situation in those days, but the bluegill was later revealed to be a fish that damages the ecosystem indigenous to Japan by preying aquatic insects, roe, and small and young fishes.
これは当時の貧しい食糧事情を思っての事であったが、ブルーギルは水生昆虫や魚卵・仔稚魚を捕食して日本固有の生態系を破壊するものであった。