The archival tags are placed either in the dorsal or the ventral side of the fish and track depth, fish-muscle and water temperatures and light. But in order to record this data, the tags must be retrieved, so the researchers are offering $500 for each archival tag. They would prefer the fish be returned intact with the tag, but if that is not possible, anglers must remove the entire tag. The necessary contact information is printed on the stalk of each tag. Anglers may keep the tagged bluefin even if it is undersized without it counting against their daily catch limit.