Original Article Biology

Fisheries Science

, Volume 79, Issue 3, pp 417-424

First online:

Vertical behavior of juvenile yellowfin tuna Thunnus albacares in the southwestern part of Japan based on archival tagging

  • Takayuki MatsumotoAffiliated withNational Research Institute of Far Seas Fisheries, Fisheries Research Agency Email author 
  • , Takashi KitagawaAffiliated withAtmosphere and Ocean Research Institute, University of Tokyo
  • , Shingo KimuraAffiliated withAtmosphere and Ocean Research Institute, University of TokyoGraduate School of Frontier Sciences, University of Tokyo

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The behavior of juvenile yellowfin tuna Thunnus albacares in southwestern Japan was investigated using archival tag data from five fish (fork length 52.5–92 cm, days at liberty 26–280 days) released near the Nansei Islands (24–29°N, 122–130°E). Vertical behavior was classified into three patterns: “shallow” (≥50 % of daytime hours at depth of <50 m), “deep” (≥50 % of daytime hours at ≥100 m), and “intermediate” (other than “shallow” or “deep”). The pooled proportion of the number of days of each behavior was 29, 25 and 46 %, respectively. The proportion of “shallow” behavior increased with fish size. The proportion of time spent near the surface at nighttime increased in the colder season, when the thermal gradient was relatively small. Surface-oriented behavior (fish remained at a depth of <10 m for more than 10 min) occurred mainly during nighttime and between November and January. Dives exceeding 500 m were occasionally observed (0.02 day−1), and one fish dived to 1230 m. The results of our study show that yellowfin tuna were typically distributed in the mixed layer or upper thermocline where the water temperature was close to the sea surface temperature and that the vertical behavior was variable.


Archival tags Vertical behavior Yellowfin tuna Northwestern Pacific Ocean