Abstract
We evaluated the pop-up archival tag data obtained from an adult Pacific bluefin tuna, com
paring with the ultrasonic transmitter data of the same tuna. The tag was designed to measure
light intensity every two minutes for estimation of daily tag geolocation and ambient tempera
ture every one hour. The tag was released from the fish and surfaced at a predetermined date
and downloaded data recorded while on the fish via the Argos satellite system. The nine tag
geolocation data showed the biases of easterly 1.10 ± 1.46 (mean ± SD) degree and southerly
1.24 ± 3.85 degree from the positions determined by the GPS during tracking of the transmit
ter. The geolocation errors were mainly attributed to the vertical migration of the bluefin tuna
around sunset and sunrise. The quick upward and downward behavior also affected the ambient
temperature data. Despite of these disadvantages, the pop-up tags have value in use for monitor
ing basin-scale movement of larger fish like tuna because of their advantage that the recapture
of the tags is not needed.
