VERTICAL AND HORIZONTAL MOVEMENTS OF STRIPED MARLIN (TETRAPTURUS-AUDAX) NEAR THE HAWAIIAN-ISLANDS, DETERMINED BY ULTRASONIC TELEMETRY, WITH SIMULTANEOUS MEASUREMENT OF OCEANIC CURRENTS

We measured the vertical and horizontal movements of striped marlin (Tetrapturus audax) off the leeward coast of the Island of Hawaii between 20 November and 18 December 1992 while simultaneously gathering data on water temperature and oceanic currents. Fish movements were monitored by ultrasonic depth-sensitive transmitters, depth-temperature profiles by an expendable bathythermograph system, and oceanic current patterns by an acoustic Doppler current profiler. Like IndoPacific blue marlin (Makaira mazara), striped marlin near Hawaii spend >85% of their time in the mixed layer (i.e., above 90 m depth). The maximum depth for striped marlin appears to be limited by water temperatures 8C degrees colder than the mixed layer, rather than by an absolute lower temperature. We also found that the horizontal displacements of some striped marlin can be strongly influenced by currents.