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.
Highlights
Utilización del hábitat vertical del atún aleta amarilla (Thunnus albacares) marcado y liberado en la Reserva de la Biosfera Archipiélago de Revillagigedo, México
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
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
Summary
Ciencias Marinas, Vol 44, No 4, 2018 and are associated with floating objects, catch volumes are low in the case of the latter (Aldana 2000, Dreyfus 2008, IATTC 2016). Internal temperature regulation rates in different fish size groups and the ability to remain at deeper depths with minimal oxygen concentrations determine the frequency and dwell time of YFT in deep zones (Brill et al 1998, Schaefer et al 2011). The objective of this study was to determine the depth preferences, during day and night hours, of YFT from different age groups and tagged with archival tags in the Revillagigedo Archipelago Biosphere Reserve, a protected natural area. El presente estudio tiene como objetivo conocer la preferencia de profundidades durante las horas del día y de la noche de los diferentes grupos de edad de los AAA marcados con marcas archivadoras en el área natural protegida de la Biosfera Archipiélago de Revillagigedo. The fish were recaptured by the purse-seine fleet, being 41 from dolphin sets and 27 from school sets (Fig. 1, Table 1)
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