Vertical movement and habitat of opah (Lampris guttatus) in the central North Pacific recorded with pop-up archival tags

Data from 11 pop-up archival transmitting tags attached to opah (Lampris guttatus, F. Lampridae) in the central North Pacific between November 2003 and March 2005 were used to describe their vertical movement and habitat. In the subtropical gyre northwest of the Hawaiian Islands, opah generally inhabited a 50–400 m depth range and 8–22 C temperatures. They were frequently found in depths of 50–150 m at night and in greater depths (100– 400 m) during the day, but were constantly moving vertically within this broad range. At night, excursions below 200 m were not uncommon and during the day they were very likely to spend some time at depths \175 m. Their vertical speeds were generally \25 cm s but on one occasion an opah descended at a burst speed of 4 m s. Vertical habitat use by individual opah apparently varied with local oceanographic conditions, but over a 24-h period the average temperature experienced was always in the narrow range of 14.7 to 16.5 C.