Tagging Study

A tagging study marks individual fish with external tags, archival or satellite tags, or chemical and genetic markers, then uses recaptures or transmitted data to estimate movement, growth, stock structure, and mortality. Conventional mark-recapture supports estimates of population size, total mortality, and exploitation rate; the recapture rate against the number released drives the math. Electronic archival and pop-up satellite tags reconstruct migration tracks and depth and temperature use for tuna, sharks, and billfish, informing RFMO stock-boundary decisions. Tagging programs depend on fisher cooperation to report recaptures, so they are often run as cooperative research with reward schemes. Tag loss, reporting rate, and tagging mortality are the bias sources that have to be corrected.