Scientists at the Farallon Islands visually document individual white sharks based on unique external characteristics (e.g. scars, marks, fin shapes, unique coloration patterns, etc.) They note any re-sightings of each recorded animal. It may soon be possible to use these visual documentations as a mark-and-recapture technique to estimate the actual numbers of animals occupying that area. 

In Southern California, scientists from California State University Long Beach are tagging white sharks and tracking their movements. Tagging enables scientists to determine how far sharks move and where they go as well as whether there's just one population or multiple populations moving up and down the coast. Recently, a shark tagged off of the California coast was tracked moving to Hawaii and back for two years in a row. 

Scientists from the Marine Conservation Science Institute are studying white sharks at Guadalupe Island, Mexico using a photo-identification database to track the visitation patterns of individual sharks as well as monitor the status of the overall population. They also use electronic tagging technologies to study the life history and migratory patterns of northeastern Pacific white sharks