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Fig. 3. Data from Barkley et al.
(1978); Brill
(1994); Dagorn et al.
(2000); Schaefer and Fuller
(2002) rendered into a
three-dimensional depiction of the vertical distribution of three tuna species
in relation to ocean temperature (black isotherms) and O2 depth
profiles (thick blue lines) in the vicinity of 160° W longitude of the
equatorial Pacific Ocean. The back panel shows sea surface temperature (SST)
isotherms in relation to latitude. Vertical panels show temperature and
O2 at depth and the occurrence of each species (shaded areas).
Skipjack of <4 kg move freely between the surface and 200 m but do not
enter water at <18°C or with less than 3.5 ml O2
l-1 (dark blue line). Larger skipjack have the same low temperature
and O2 limits but are also restricted by warm temperatures:
4–9 kg skipjack are restricted to <26°C whereas >9 kg skipjack
are confined to 18–22°C. Yellowfin extend from the surface to depths
greater than 400 m but have the same O2 limit as skipjack. Bigeye
are found at greater depths than the other two species and have an
O2 limit of 1.0 ml O2 l-1 (light blue
line).
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