Towards the end of the 19th century Spanish, Portuguese, German and Fernandino planters started developing large cacao plantations. With the indigenous Bubi population decimated by disease and forced labour, the island's economy came to depend on imported agricultural contract workers. A Labour Treaty was signed with the Republic of Liberia in 1914, the transport of up to 15,000 workers was orchestrated by the German Woermann-Linie. The Liberian labour supply was cut off in 1930 after an International Labour Organization (ILO) commission discovered that contract workers had "been recruited under conditions of criminal compulsion scarcely distinguishable from slave raiding and slave trading".