Vertical habitat utilization by tagged yellowfin tuna (Thunnus albacares) released in the Revillagigedo Archipelago Biosphere Reserve, Mexico

Abstract

A description of vertical habitat use by yellowfin tuna, Thunnus albacares, captured and released with archival tags in the Revillagigedo Archipelago Biosphere Reserve, Mexico, during the 2006–2011 period is given. An analysis was made of internal and ambient temperatures, depth, and time of day registered in 68 archival tags recovered from tuna caught mostly in sets associated with dolphins by Mexican purse-seine vessels. Tuna were classified into 3 age groups (I, II, and III) for analyses. Vertical movements were analyzed by dividing the water column into 10 depth strata. The 3 age groups remained the longest in the uppermost stratum (0–25 m), and their presence began to diminish in subsequent strata, with some occasional visits at >500-m depths. In the >500 m stratum, age group III was the one with the longest time investment with 45 min on average. Presence at different depths throughout the day showed significant differences among age groups (Wald’s test expressed as χ², P < 0.05). The physiological adaptation of yellowfin tuna to maintain minimal changes in its internal temperature at different depths gives it the advantage to expand its food search to deep zones where temperature oscillates around 5 ºC.