Yellowfin and Bigeye tuna
Follow the key for identification shown by the numbers !
①Pectoral fin shape and length
Good for identification of;
-
Small size (under FL40cm) △
-
Medium size (FL45cm to FL120cm) 〇
-
Lage size (over FL120cm) ×
Pectoral fin is as long as the base of 2nd dorsal fin= Yellowfin tuna
Pectoral fin extends the base of 2nd dorsal fin= Bigeye tuna
Edge of the Pectoral fin is rather rounded= Yellowfin tuna
Edge of the Pectoral fin is rather sharpe= Bigeye tuna
Notes;
Best indicator as a first step, however individual difference exists.
Photo examples
Photo examples
Photo examples
②Caudal fin
Good for identification of;
-
Small size (under FL40cm) △
-
Medium size (FL45cm to FL120cm) 〇
-
Lage size (over FL120cm） 〇
Distinct notch observed = Yellowfin tuna
Notch like shape is rather smooth = Bigeye tuna
Notes;
Good indicator, however caudal fin could be easy damaged during the fishing process or condition of preservation. Also it has some individual differences.
Examples photos
③Pattern (belly)
Good for identification of;
-
Small size (under FL40cm) 〇
-
Medium size (FL45cm to FL120cm) 〇
-
Lage size (over FL120cm） ×
Regular pattern (unbroken stripes with regular spots) = Yellowfin tuna
Irregular pattern (broken stripes with random spots)= Bigeye tuna
Notes;
Good indicator, however pattern can become unclear depending to the condition of preservation.
Example photos
Example photos
④Liver (needs dissecting)
Good for identification of;
-
Small size (under FL40cm) 〇
-
Medium size (FL45cm to FL120cm) 〇
-
Lage size (over FL120cm） 〇
One part of the liver extends and pointed, with no clear lines = Yellowfin tuna
Liver is separated in approximately same size, with clear lines around the edge = Bigeye tuna
Notes;
Perfect indicator for all sizes, however needs dissecting.
Example photos
⑤Swim bladder shape
(needs dissecting)
Good for identification of;
-
Small size (under FL40cm) △
-
Medium size (FL45cm to FL120cm) △
-
Lage size (over FL120cm） △
When inflated, present in the anterior half of the body cavity = Yellowfin tuna
When inflated, present throughout the body cavity= Bigeye tuna
Notes;
Condition of swim bladder (inflated or not inflated) may depend on fish condition and needs careful dissecting for observation.
Example photos (Inflated condition)
Example photos (Moderately inflated condition)
Example photos (Non-inflated condition)