Actually, mullet are also found in Japanese waters, but as soon as winter comes, they swim south to lay their eggs, so the Japanese have to import the roe from Taiwan.
其實日本沿海也有烏魚，但是一到冬天，氣溫降低，烏魚就結群南遊產卵，日人享受不到自產的魚子，只好向台灣購買。