The Andō controlled trade with the Ainu via Tosaminato. Some records indicate that Port Tosa was destroyed in an enormous tsunami in 1340; however, historical records for this period are scarce and lack veracity. What is more certain is that the Andō were defeated by the Nanbu clan in 1442, and the port fell rapidly into disuse after that date. During the Edo period, the port was rebuilt as the point where rice harvested in the Hirosaki Domain was exported to the Osaka, but it never regained its former prosperity and fell into disrepair again after the proliferation of railroads during the Meiji period. The ruins of Port Tosa are preserved today as a National Historic Site. The folk song and dance pays tribute to the lagoon and the port. Economically, Lake Jūsan is noted today for its production of "shijimi" clams.