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NATURAL HISTORY

ATLANTIC WHITE MARLIN } Tetrapturus albidus
FAMILY: Istiophoridae

DESCRIPTION: The white marlin is designed for fast, continual swimming. A sleek, powerful fish, the marlin is deep blue on the upper half of its body and silvery white underneath. The marlin’s body is densely covered with bony scales. It has a long, sharp-pointed bill and a rounded dorsal fin. The tail fin is large, stiff, and deeply forked. White marlin can grow to be as long as nine feet and weigh 180 pounds, with males slightly smaller than females.

HABITAT: White marlin are found throughout tropical and temperate portions of the Atlantic Ocean. They inhabit deep areas of the open ocean with surface temperatures above 70 degrees. They are generally near the water’s surface and can be found seasonally in coastal waters.

RANGE: White marlin occur throughout the Atlantic Ocean from Nova Scotia to Argentina and from southern Europe to South Africa. They are found at higher latitudes in the summer, when water temperatures are sufficiently warm.

MIGRATION: White marlin migrate seasonally from a summer habitat in the northern Gulf of Mexico or off the Middle Atlantic coast (from Cape Hatteras to Cape Cod) to a winter habitat in the southern Caribbean (off the northern coast of South America from Colombia to the Guianas). The latter migration pattern is northward along the length of the Middle Atlantic summering grounds, easterly offshore in late summer and early fall, and then southward to the wintering grounds. No trans-Atlantic or trans-equatorial migrations have been recorded despite a substantial fishery for white marlin in the South Atlantic, particularly off Brazil. The northern migration of the species seems to be related to water temperature, with the white marlin reaching higher latitudes as the water grows warmer.

BREEDING: Spawning only once per year, white marlin migrate to subtropical waters and spawn in early summer. It is believed that they spawn in pairs, as opposed to communal or mass spawning.

LIFE CYCLE: White marlin live for 25 to 30 years.

FEEDING: White marlin feed on small fish, such as herring and dolphinfish, and on invertebrates, such as squid, which are swallowed whole. The foraging and movement patterns of white marlin reflect the distribution and scarcity of their prey in the open seas. They must cover vast expanses of ocean in search of sufficient amounts of food. White marlin are solitary hunters, although these predators sometimes become concentrated in areas where prey is dense.

THREATS: While w hite marlin are highly sought after in recreational sport-fishing, this accounts for only a small percentage of marlin mortality. The vast majority of Atlantic white marlin are killed by industrial-scale swordfish and tuna longliners using non-selective fishing gear.

POPULATION TREND: The Atlantic white marlin has been reduced to less than 10 percent of its historic population size in the Atlantic Ocean. The species has steadily declined by 3 percent each year since monitoring began in the mid-1980s.

 

Photo © Bill Boyce