New Zealand Journal of Marine and Freshwater Research abstracts
DNA identification of Pacific bluefin tuna (Thunnus orientalis) in
the New Zealand fishery
P. J. SMITH
L. GRIGGS
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 14 901, Kilbirnie
Wellington, New Zealand
email: p.smith@niwa.cri.nz
S. CHOW
Division of Pelagic Fish Resources
National Research Institute of Far Seas Fisheries
Orido 5-7-1, Smimizu
Shizuoka 424-8633, Japan
Abstract Muscle samples were collected from 69 specimens
identified as Pacific bluefin tuna (
Thunnus orientalis) (Temminck and
Schlegel, 1844) in the New Zealand Exclusive Economic Zone (EEZ) between 1990
and 2000. Identifications before 1996 were based on body size and colour of the
caudal keel; later identifications were mostly based on the shape of abdominal
cavity. The tissue samples were tested with a diagnostic mitochondrial DNA
marker that distinguishes southern bluefin
Thunnus maccoyii (Castelnau,
1872) and Pacific bluefin tuna
T. orientalis; 59 specimens were
confirmed as
T. orientalis and 10 as
T. maccoyii.
Specimens recorded as Pacific bluefin tuna by the shape of the abdominal cavity
were correctly identified as
T. orientalis, and this character can be
used to identify large specimens landed on tuna vessels. Some specimens
recorded as Pacific bluefin tuna on the basis of colour and size were
T.
maccoyii; and early records of
T. orientalis in New Zealand waters,
based on these characters, are unreliable. Unusual colour patterns were
reported in some specimens of
T. orientalis but not
T. maccoyii.
The Pacific bluefin tuna
T. orientalis accounted for less than 0.3% of
the bluefin tuna catch in the New Zealand EEZ during the 1990s.
Keywords bluefin tuna; Thunnus maccoyii; Thunnus
orientalis; mitochondrial DNA; PCR
M01022
Received 5 March 2001; accepted 5 April 2001
PDF file of entire paper: medium quality (1391K); (scanned from paper original: notes about this process)
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