| Identification
& Biology: |
This
small tuna has the typical fusiform, tuna body shape. The
back is dark metallic blue, the sides are silvery-gray and
the belly is white. Many have traces of a bronze-colored line
down each side. The most reliable identifying characteristic
is the color of the small finlets located behind the dorsal
and anal fins. In the other four species of tuna, they are
yellow or yellow, edged with black. In the blackfin, they
are distinctly dusky, although they may have a yellowish tinge.
This tuna seems to have less of a fish-based diet than other
tunas and will actually consume the tiny larvae of stomatopods
(king shrimp or mantis shrimp), true shrimp, and crabs, as
well as fish larvae. It does, of course, also eat juvenile
and adult fish and squid. They are a short-lived, fast-growing
species, with a 5 year old fish being considered old. They
reach sexual maturity at two years old and 4-6 pounds in weight
and spawn in the open sea during the summer. Blackfin tuna
are a warmer-water fish, preferring water temperatures over
68ºF. What they lack in size, they make up for in numbers
and willingness to bite. See Yellowfin
Tuna for more information on tuna biology. |
