The earliest known family settled on Vilsandi in 1826 and in 1896 this family took the surname of Mänder. Over time, as the letter “ä” was not familiar to the various non-Estonian seamen in the area, some family members changed Mänder to Mender because it was easier to spell. By 1860, 18 families lived on the island. In 1934 a census recorded that 32 families and 169 people lived on Vilsandi, sustained mainly by fishing (flounder, cod, salmon) and seafaring. The surrounding ocean is shallow with some depths to . In 1931 a seabird museum was built on Vilsandi and before World War II (1939–1945) there were about 200 permanent residents on the island and about 3,000 – 5,000 tourists that would visit during the summer months.