The Great Marlin Race relies upon Wildlife Computers MK-10 pop-up tags. Each tag
is attached to a marlin with a titanium dart, attached to a heavy monofilament leader
connected to a special pin at the bottom of the tag. Once the fish is tagged, the
tag records depth, temperature and light - which is used to calculate the fish's
location. At a pre-programmed date, the pin at the bottom of the tag corrodes away,
setting the tag free from the fish. The foam float at the top of the tag carries
it to the surface, allowing the antenna to relay summaries of the stored data, via
the Argos satellite system, back to the laboratory.