Ecology of Thunnus obesus
 
Main Ref. Collette, B.B. and C.E. Nauen, 1983
Distribution
Marine - Neritic
  • supra-littoral zone
  • littoral zone
  • sublittoral zone
Marine - Oceanic
  • epipelagic
  • mesopelagic
  • epipelagic
  • abyssopelagic
  • hadopelagic
Brackishwater
  • estuaries/lagoons/brackish seas
  • mangroves
  • marshes/swamps
Freshwater
  • rivers/streams
  • lakes/ponds
  • caves
  • exclusively in caves
Highighted items on the list are where Thunnus obesus may be found.
Remarks Temperature and thermocline depth seem to be the main environmental factors governing the vertical and horizontal distribution of this species (Ref. 168). Bigeye tuna are more tolerant of lower temperatures and lower dissolved oxygen concentration than are other tunas and tend to occupy deeper waters (Ref. 30326). For example, during the day, adult bigeye tuna inhabit the thermocline zone at about 150-250 m in tropical waters where temperatures descend to almost 10°C, provided dissolved oxygen concentration is more than 1 mg per l (Ref. 28952, 30327). The tuna make occassional short ascents to 100 m or shallower (Ref. 6390). Young bigeye tuna have not been reported outside tropical waters (Ref. 30326). In Australia, bigeye tuna smaller than 20 kg may form surface-dwelling schools of similar sized fish with other species such as yellowfin tuna and skipjack tuna (Katsuwonus pelamis). Schools of only bigeye tuna are less common (Ref. 30328). In tropical waters, young bigeye tuna are often caught 50-100 m below floating objects such as logs and fish aggregating devices (Ref. 30326). Adults tend to be solitary (Ref. 6390). Behavioural studies in Hawaiian waters using ultrasonic tags (Ref. 30329) found that the distribution of adult bigeye tuna was closely correlated with the 15°C isotherm during the day (Ref. 6390). Like yellowfin tuna, bigeye tuna move into the warmer surface waters (within 50 m of the surface) at night. Feed during the day and at night. In Hawaii, more abundant in late fall through late spring.

Substrate

Substrate
Substrate Ref.
Special habitats
Special habitats Ref.

Associations

Ref.
Associations
Associated with
Association remarks
Parasitism

Feeding

Feeding type mainly animals (troph. 2.8 and up)
Feeding type ref Collette, B.B. and C.E. Nauen, 1983
Feeding habit hunting macrofauna (predator)
Feeding habit ref Collette, B.B. and C.E. Nauen, 1983
Trophic level(s)
Original sample Unfished population Remark
Estimation method Troph s.e. Troph s.e.
From diet composition 4.49 4.27 0.64 Troph of adults from 1 study.
Ref. Fuentes, H., E. Antonietti and A. Alano, 1988
From individual food items 4.48 0.93 Trophic level estimated from a number of food items using a randomized resampling routine.
(e.g. 346)
(e.g. cnidaria)
Entered by Luna, Susan M. on 06.10.91
Modified by Pablico, Grace Tolentino on 07.01.08
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