The economy of Hull was built on trading and seafaring, firstly whaling and later seafishing. Merchant's houses such as Blaydes House and some warehouses survive in the Old Town, where trade was centred on the River Hull, later shifting to the Humber docks. Another major industry was oilseed crushing. Although the fishing industry declined in the 1970s due to the Cod Wars, the city remains a busy port, handling 13 million tonnes of cargo per year. The port operations run by Associated British Ports and other companies in the port employ 5,000 people. A further 18,000 are employed as a direct result of the port's activities.