UPDATE: 7 October 2012, I am finding some conflicting dates from certain authors of literature regarding the year and even the number of Chamorros from the Gani Islands that were relocated to Guam. Farrell's figures makes much more sense and now we can more accurately visualize in the updated Population Comparison chart the decline of the Chamorro population from conversion-to-conquest-to-colonization.

Sometime after the Chamorro-Spanish wars and and during the 1690s, with the exception of Rota, Chamorro families from the Northern Mariana Islands were forced to relocate to Guam. In 1694, Chamorros from Tinian and Aguiguan were relocated and resided in Pago and Hagatña. By 1698, aApproximately 1,200 (Russell, 1998:91) or 1,920 (Farrell, 2011:182)  Chamorros from the "Gani Islands" (these were the islands north of Saipan) were relocated and settled in Inarajan and other southern villages. (Russell, 1998:98) The other two southern villages on Guam are Merizo and Umatac. The 1727 Census reflects the Chamorro relocation and settlement in that only Guam and Rota were the only islands detailed in the census.  Also, occurring that same year iIn 1698, the inhabitants of Saipan too were forced to move to Guam. (Spoehr, 1954:54).

References:

Don A. Farrell. 2011. History of the Mariana Islands to Partition. Public School System, CNMI: CNMI

Levesque, Rodrigue. 1992. Population Census of the Marianas in 1727 – Fewer Than 3,000 Inhabitants, p17-45. History of Micronesia, vol. 13: Failure at Ulithi Atoll, 1727-1746. Levesque: Quebec, Canada

Scott Russell. 1998. Gani Revisited: A Historical Overview of the Mariana Archipelago's Northern Islands. Pacific Studies. 21(4), p.83-105. Retrieved from: https://ojs.lib.byu.edu/spc/index.php/PacificStudies/article/viewFile/10136/9784

Alexander Spoehr. 1954. Saipan – The Ethnology of a War-Devasted Island. Fieldiana: Anthropology, 41. Chicago Natural History Museum: IL