Thunnus Albacares
English language common names referring to this tuna include yellowfin tuna, yellow fin tuna, allison tuna, long fin tunny, longfin, Pacific long-tailed tuna, and tuna.
Colour, Shape and Size
The body is metallic dark blue or greenish above, while the belly and lower sides are silvery white and crossed by many vertical, interrupted lines. Perhaps most distinctly, a golden stripe runs along the side. The second dorsal and anal fins and finlets are bright yellow, and the finlets are bordered by a
are bordered by a narrow band of black.
Natural History
Yellowfin is a large tuna. Its body is strongly fusiform, and deepest under its first dorsal fin, while tapering considerably towards the caudal peduncle. Two dorsal fins are present. In adults, the second dorsal fin is very long, as is the anal fin, which is directly below the second dorsal. These fins become relatively longer in larger individuals. The pectoral fin is also long, reaching beyond the space between the dorsal fins. The caudal peduncle is very slender and includes three sets of keels. Seven to ten dorsal and ventral finlets are present. Scales are lacking behind the corselet, a band of large scales forming a circle around the body behind the head. A swim bladder is present. The eyes are small; teeth are small and conical.
Similar species occurring in the same areas as yellowfin tuna include bigeye tuna (Thunnus obesus), blackfin tuna (T. atlanticus), and albacore (T. alalunga).
Size at maturity varies by region, and may also be different between individuals found near- and offshore. All yellowfin are reproductively mature by the time they reach a length of 47 in. (120 cm) fork length (corresponding to an age of 2-3 years), however some are mature by 20-23 in. (50-60 cm) fork length (corresponding to 12-15 months). In juvenile fishes and adults up to 55 in. (140 cm), the sex ratio is approximately 1:1. The proportion of females declines in fishes larger than this size, however the reason for this is not understood.
Capture
At the surface, they are primarily caught by purse seine. A purse-seine vessel first encircles a school with a large net. The bottom of the net is closed off, and the net is pulled upwards and brought aboard the boat, where the catch can be released by reopening the bottom of the net once it is out of the water. The purse-seine method is central to the "dolphin-safe" tuna fishing legislation.
Specific Catch Restrictions
Commercial catches are subject to quota
