Habitat and behaviour of adult yellowfin tuna (Thunnus albacares) in the waters off southwestern Taiwan determined by pop-up satellite archival tags

Abstract

Yellowfin tuna (Thunnus albacares) is an economically important species for longline and trolling fisheries in the waters off the southwestern coast of Taiwan, yet this species' movement patterns remain poorly understood. This study provides the first information on the movement and behaviour of adult yellowfin tuna using pop-up satellite archival tags in the waters off the southwestern coast of Taiwan. In total, 11 tuna (ranging from 116 to 135 cm in fork length) were tagged and released from 2011 to 2013. Seven fish were successfully tracked to provide information on depth and temperature preferences as well as horizontal movements. The majority of the vertical movements (30.3%) of yellowfin tuna occurred in the 50-m depth range in mixed layers. The mean swimming depth was 74.4 m (±50.7 m) during the daytime and 94 m (±72.5 m) at nighttime, which was a contrast to the findings in other waters. The maximum diving depth was 1000 m, where the water temperature was approximately 4°C. This value was similar to the measurements made by a CTD near a depth of 1000 m, where the water temperature was approximately 4.2°C and the O 2 level was 3.0 mg l À1. One of the tuna travelled 190 NM (straight distance) in 37 days, with most of its horizontal movements (70.6%) occurring at temperatures that ranged from 26 to 28°C, suggesting that yellowfin tuna have a preference for this temperature range throughout the period of PAST observation.

Relationship between temporal–spatial distribution of fishing grounds of bigeye tuna (Thunnus obesus) and thermocline characteristics in the Atlantic Ocean

“…The lower temperature of the thermocline in the central fishing grounds offshore Namibia ranged from 14 to 14.9°C, higher than the temperature of Tropical Atlantic. Those results suggest that the bigeye tuna stays in shallow (daily and night) in high-latitude than low-latitude, this consistent with the results of Weng et al [18], who stated that the yellowfin tuna inhabit shallow in cooler water than in warm water. We deduce that the bigeye has similarly biological habitat.…”

Cookie‐cutter shark Isistius spp. predation upon different tuna species from the south‐western Atlantic Ocean

“…bite marks, is known to use superficial waters, i.e . the epipelagic level of the water column, within the mixed layer at night and to sporadically dive towards greater depths during the day, sometimes >1000 m (Dagorn et al, ; Schaefer et al, ; Weng et al, ). Hence, some level of habitat overlap between T. albacares and Isistius spp.…”

Observations of vertical movements and depth distribution of migrating female lumpfish (Cyclopterus lumpus) in Iceland from data storage tags and trawl surveys

“…These ascents and descents were substantial, with daily vertical ranges of over 100 m being common. There is a consensus that the vertical movements of pelagic fish through the water column are linked with feeding (Hays et al, 2009;Weng et al, 2009;Dewar et al, 2011;Armannsson and Jó nsson, 2012). As the stomachs of lumpfish caught during the IGFS contain large amounts of water and food (Kennedy, pers.…”

“…Kennedy et al Weng et al, 2009;Dewar et al, 2011). This may be because the diet of lumpfish is diverse, consisting of both pelagic and benthic organisms (Davenport, 1985), thus they may feed on prey which does and does not exhibit diel patterns in vertical behaviour.…”