This pelagic and migratory species occurs in
tropical and warm temperate oceanic waters.
In the Atlantic Ocean it is found from 45°N
to 35°S, and in the Pacific Ocean from 48°N
to 48°S. It is less abundant in the eastern
portions of both oceans. In the Indian Ocean
it occurs around Ceylon, Mauritius, and off
the east coast of Africa. In the northern
Gulf of Mexico its movements seem to be
associated with the so called Loop Current,
an extension of the Caribbean Current.
Seasonal concentrations occur in the
southwest Atlantic (5°-30°S) from January to
April; in the northwest Atlantic (10°-35°N)
from June to October; in the western and
central North Pacific (2°-24°N) from May to
October; in the equatorial Pacific
(10°N-10°S) in April and November; and in
the Indian Ocean (0°-13°S) from April to
October.
Japanese longliners report that the blue
marlin is the largest of the istiophorid
fishes. It apparently grows larger in the
Pacific. All giant marlins are females, and
male blue marlin rarely exceed 300 lb (136
kg). The pectoral fins of blue marlin are
never completely rigid, even after death,
and can be folded completely flat against
the sides except in the largest specimens.
The dorsal fin is high and pointed
anteriorly (rather than rounded) and its
greatest height is less than the greatest
body depth. The anal fin is relatively large
and it too is pointed. Juveniles may not
share all the characteristics listed above,
but the peculiar lateral line system is
usually visible in small specimens. In
adults it is rarely visible unless the
scales or skin are removed. The vent is just
in front of the anal fin, as it is in all
billfish except the spearfish. The back is
cobalt blue and the flanks and belly are
silvery white. There may be light blue or
lavender vertical stripes on the sides, but
these usually fade away soon after death,
and they are never as obvious as those of
the striped marlin. There are no spots on
the fins.
They are known to feed on squid and pelagic
fishes, including blackfin tuna and frigate
mackerel. A powerful, aggressive fighter,
they run hard and long, sound deep, and leap
high into the air in a seemingly
inexhaustible display of strength. Fishing
methods include trolling large whole baits
such as bonito, dolphin, mullet, mackerel,
bonefish, ballyhoo, flying fish and squid as
well as various types of artificial lures
and sometimes strip baits.
Some taxonomists believe that the Atlantic
and Pacific blue marlins are closely related
but separate species. They apply the
scientific name Makaira nigricans, Lacepede,
1892, to the Atlantic species only and the
name Makaira mazara (Jordan & Snyder, 1901)
to the Pacific and Indian Ocean species.
Others treat the two populations as
subspecies, Makaira nigricans nigricans and
Makaira nigricans mazar
