Marlins are large fish with elongated, bill-like snouts, fairly high dorsal fins, and a streamlined body. They belong to the order Perciformes and the suborder Scombroidei. Marlins are among the fastest of all fish and are highly valued by sporting fishers.
The order Perciformes is the largest and most diverse of all fish orders, encompassing about 8,000 species. Distributed worldwide, fish of this order exist in both marine and freshwater habitats and represent species of diverse sizes, habitats, and behaviors. This order is broken into 150 families and 1,370 genera.
The suborder Scombroidei is divided into six families. The Sphyraenidae family includes the barracudas, classified in one family (Sphyraena ) and 20 species. The Trichiuridae family includes nine genera and 32 species of hairtails, ribbonfishes, and cutlassfishes. The Gempylidae contains 16 genera and 23 species of snake mackerels. The Scombridae includes the albacores, bonitos, mackerels, and tunas, classified in 15 genera and 53 species. The Xiphiidae family contains only one species, the broadbill swordfish (Xiphias gladius ), distinguished from the Istiophoridae by a lack of pelvic fins and a long, flattened bill. The Istiophoridae family includes marlins, sailfishes, and spearfishes. Members of this family have an elongated, rounded snout, called a bill, and live in tropical and subtropical seas. The Istiophoridae includes three genera and about nine species. The three genera are: Istiophorus or sailfishes; Tetrapturus or spearfishes; and Makaira or marlins. The genus Makaira contains two species of marlin—the blue marlin (M. nigricans ) and the black marlin (M. indica ). Marlins are different from the other two genera in that their dorsal fins do not measure in height as much as their bodies measure in depth. As with other fish in their family, the dorsal fins are long with many rays, and their tail has two sets of side keels.
Marlins are among the swiftest fish and greatest leap-ers. While the sailfish are commonly regarded as the fastest swimming fish, the blue marlin offers strong competition. It is one of the few fish that can swim fast enough to eat tuna species on a regular basis. In fact, marlins can attain speeds of up to 50 mph (80 km/h). Furthermore, when they are hooked on a line, they struggle heroically, sometimes jumping more than 40 times.
The marlins’ speed makes them fierce predators. Rushing a school of fish, marlins thrash with their bill, wounding and killing many fish unlucky enough to be in their path. Once the slaughter is finished, they return to feast on the dead and wounded.
There are four species of fish with the common name marlin. These fish are classified into two genera. In the strictest sense, marlins belong to the genus Makaira. Examples of marlins in this genus are the blue marlin and the black marlin. Two additional species with the common name marlin are the striped marlin (Tetrapturus audax ) and the white marlin (Tetrapterus albidus ).
Blue marlins are colored blue or gray-blue on the back, and their shading gets lighter toward their belly, which is silver. These marlins measure 10-15 ft (3-4.6m) in body length. Their mature weight commonly varies from about 200-400 lb (91-181 kg), but they can weigh more than 1,800 lb (800 kg). These fish have a streamlined body with a crescent shaped tail. They live in tropical and temperate seas throughout the world. They are found in temperate seas in the eastern Atlantic, ranging from northern Spain south to South Africa, and in the western Atlantic as far north as Massachusetts and as far south as Uruguay. Blue marlins swim in open seas and make regular seasonal migrations to the equator in the winter and away from it in the summer. They swim in surface waters and are a highly prized sporting fish.
The black marlin is the largest of all of the billfish. It reaches 16 ft (5 m) in body length and can weigh more than 1,500 lb (681 kg). Its pectoral fins are rigid and do not fold into its body. It lives in the Pacific Ocean near the surface of warm, open waters from southern California to Chile.
The striped marlin is similar in appearance to the blue marlin, having an elongated bill and a streamlined body. The striped marlin lives in the Indian and Pacific Oceans and is more likely to inhabit temperate waters, such as from Oregon to Chile. It lives in the open sea, but sometimes will be seen in inshore waters. This species is distinguished by dark-blue or white vertical bars on its sides. Additionally, its pelvic fins are much longer than its pectoral fins and it has a relatively high dorsal fin. The striped marlin spawns from May to August in the Northern Pacific. It grows to about 10 ft (3 m) in length and eats fish and various species of deepwater and surface squid. It is a highly specialized sport fish and also an excellent food fish.
Dorsal fin —A fin located on the back of a fish.
Pectoral fin —The uppermost of paired fins, usually located on the sides; this fin follows the gill openings.
Pelvic fin —The fin usually located and to the rear of the pectoral fin.
The white marlin usually weighs about 50 lb (23 kg), but can measure as much as 10 ft (3 m) in length and weigh up to 180 lb (82 kg). This migratory fish is found in the eastern part of the Atlantic Ocean, from south of Portugal to the southwestern Mediterranean, and in the western Atlantic from Nova Scotia south to Brazil. It has also occurs in the Gulf of Mexico and the Caribbean. The white marlin is bluish green, brown, or gray on top and silver underneath.
Marlins are among the most popular sporting fish in the world. However, their numbers are decreasing because of intense commercial and sport overfishing. Because they are relatively large, old fish, they frequently have naturally high concentrations of mercury in their flesh, and concerns about the potential human-health hazard of eating these species limits the commercial hunt to some degree. There is a pressing need for better conservation measures in support of these valuable species, or they will become endangered.
Nelson, Joseph S. Fishes of the World. 4th ed. New York: John Wiley & Sons, 2006.
Webb, J.E. Guide to Living Fishes. Macmillan Publishing, 1991. Whiteman, Kate. World Encyclopedia of Fish and Shellfish. New York: Lorenz Books, 2000.