Ecology Summary - Thunnus obesus

Língua:

Ref. principal	Collette, B.B. and C.E. Nauen, 1983
Notas	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.

Ref. principal

Collette, B.B. and C.E. Nauen, 1983

Notas

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.

Aquatic zones / Water bodies

	Marine - Neritic	Marine - Oceanic	Brackishwater	Freshwater
Marine zones / Brackish and freshwater bodies	supra-littoral zone littoral zone sublittoral zone	epipelagic mesopelagic epipelagic abyssopelagic hadopelagic	Estuários/lagunas/áreas estuarinas manguezais pântanos/brejos	rivers/streams lakes/ponds Cavernas exclusivamente

Highighted items on the list are where Thunnus obesus may be found.

Habitat

Substrato
Substrate Ref.
Habitats especiais
Special habitats Ref.

Associações

Ref.
Associações
Associada com
Comentários sobre associação
Parasitismo

Alimentação

Tipo de alimentação	mainly animals (troph. 2.8 and up)
Feeding type Ref.	Collette, B.B. and C.E. Nauen, 1983
Hábito alimentar	hunting macrofauna (predator)
Feeding habit Ref.	Collette, B.B. and C.E. Nauen, 1983

Trophic Level(s)

Estimation method	Amostra original		População virgem (não pescada)		Nota
Estimation method	Troph	s.e.	Troph	s.e.	Nota
Da composição da dieta	4.49		4.27	0.64	Troph of adults from 1 study.
Dos itens alimentares individuais	4.48	0.93			Trophic level estimated from a number of food items using a randomized resampling routine.
Ref.	Fuentes, H., E. Antonietti and A. Alano, 1988

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Aquatic zones / Water bodies

Habitat

Associações

Alimentação