Greetings Trevor, In 1878 Courland [Kurland] was about half of the land of Latvia. You need to specify a town to improve your chances. Jamaiker is not a Latvian name. I feel that it probably is a Jewish last name. The er ending following a place name is the reason why I think so. Berliner, Hamburger, Danciger, Goldinger are Jewish surnames. The J is not pronounced as the English J but like the y in yes. The surname Jamaiker has to be rare. From 1850 on people in the countryside in considerable numbers moved to the capital Riga [never part of Kurland] which is home to about third of the people in Latvia. I have found addresses in Riga for two persons who may have connection to you.  2007 Irina Jamaikina-- during WWII one may have wanted to hide one's Jewishness. Irina is Russian first name.  1938 Izaks Jamaikers home and business address-- the s on end is Latvianization of name. Izaks is Jewish first name.