Britain's interest in the Upper Guinea region declined with the end of the British slave trade in 1807 and became focused on Sierra Leone after the Boloma Island settlement was abandoned. At the start of the 19th century, the Portuguese felt reasonably secure in Bissau and regarded the neighbouring coastline as their own. Their control was tenuous: for much of the 19th century the Portuguese presence in Guinea was mainly limited to the rivers of Guinea, the settlements of Bissau, Cacheu and Ziguinchor (the last now in Senegal). Elsewhere it was preserved, with little official assistance, by local Creole people and Cape Verde islanders, who owned small plantations (pontas).