Marlin
Marlins are a group of fast-swimming fish belonging to the Istiophoridae family, typically found in the warm surface waters of the Pacific, Indian, and Atlantic Oceans. There are four commonly recognized species: white marlin, striped marlin, Atlantic blue marlin, and Indo-Pacific blue marlin, each varying in size and habitat. Known for their remarkable speed, marlins can swim up to 40 miles (65 kilometers) per hour and employ unique feeding strategies, such as raising their dorsal fins to corral prey or using their long, rounded bills to strike fish and squid.
Marlins possess distinctive physical features including long, slender bodies, large forked tails, and multiple dorsal fins. They can be confused with swordfish, which lack the undersides fins that marlins have and possess flattened bills instead. The white marlin is the smallest, typically growing up to nine feet long, while the black marlin can weigh as much as 2,000 pounds. Marlins have varied lifespans, with some species living up to 30 years, and females generally outlive males. These fish play an essential role in marine ecosystems and are often sought after in sport fishing due to their size and speed.
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Marlin
The four most commonly-recognized species of marlins live mainly near the surface of warm ocean waters where they feed on fish and squid. A marlin can swim at 40 miles (65 kilometers) per hour.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Istiophoriformes
Family: Istiophoridae
Genus: Various (see below)
Species: Various (see below)
The warm surface waters of the Pacific, Indian, and Atlantic Oceans are home to the marlins. These fast-swimming fish can cruise 40 miles (65 kilometers) per hour. They frequently swim near the surface where they find fish and squid. Marlins may raise dorsal, or back, fins to prevent prey from escaping. Another feeding technique is to swim into a school of fish and strike their prey with their long, rounded, slender, sharply-pointed bills, or snouts. Their bills have caused them, along with swordfish, sailfish, and spearfish, to be named billfish.
Marlins have long, stretched, rounded bodies with large, forked tails. A dorsal fin runs along the back of each fish which rises to a high point in the front near the head and becomes short near the caudal region. A second or third smaller dorsal fin may sit behind the first in some species. Two anal fins are attached on the underside slightly ahead of the tail. Some species have small pelvic fins beneath their two pectoral fins.
The marlins and the swordfish resemble each other, and some people have confused them. One way to identify these species is that marlins have fins on their undersides, while swordfish do not. Another difference is that the bills of marlins are rounded, whereas those of swordfish are flattened. Marlins have two ridges along each side of their bodies just in front of their caudal fins, but swordfish only have one ridge on either side.
The smallest of the four species of common marlin is the white marlin (Kajikia albida). It lives in the Atlantic Ocean and commonly grows to be nine feet (a little over 2 1/2 meters) long and weighs 100 to 180 pounds (45 to 80 kilograms). A white marlin has blue-green skin with a pale belly and pale vertical bars along its body.
The striped marlin (Kajikia audax) makes its home in the waters of the Indo-Pacific and is larger than the white marlin. Body lengths are unavailable, but members of this species often weigh 275 pounds (125 kilograms), while there is a report of one weighing nearly 420 pounds (190 kilograms). Pale vertical bars run between the blue skin on its back and sides and the white skin on its belly. They are the only marlin species to slash their prey instead of stabbing it. They spawn in the summer, laying up to 120 million eggs in one season. They release eggs in batches over several weeks. The young reach maturity after two to three years.
The next largest in the family of marlins are the vulnerable Atlantic blue marlins (Makaira nigricans) and the Indo-Pacific blue marlins (Makaira mazara). They may grow to 16 feet (5 meters), though most are around 11 feet (3 1/2 meters). This fish lives in warm and tropical seas around the world. Deep blue skin on its back and sides becomes silver on its belly, and light, vertical bars stripe its sides.
Often considered the largest marlin species, a full-grown black marlin (Istiompax indica) measures at least as long as the blue marlin, if not longer. It may weigh as much as 1,550 to 2,000 pounds (700 to 900 kilograms). The skin on its back and sides is blue or grayish-blue and is lighter on its underside. This large fish swims in the Indo-Pacific waters.
Other species in the Istiophoridae family include the longbill spearfish (Tetrapturus pfluegeri), roundscale spearfish (Tetrapturus georgii), Mediterranean spearfish (Tetrapturus belone), and shortbill spearfish (Tetrapturus angustirostris).
Female marlins usually live longer than males. The lifespan of striped marlins is up to 10 years. Blue, white, and black marlin species live 20 to 30 years.
Bibliography
"Blue Marlin." National Geographic Society, www.nationalgeographic.com/animals/fish/facts/blue-marlin. Accessed 1 May 2024.
"Striped Marlin." Australian Fisheries Management Authority, 2 May 2023, www.afma.gov.au/species/striped-marlin#referenced-section-2. Accessed 1 May 2024.
"White Marlin." Ocean Conservancy, oceanconservancy.org/wildlife-factsheet/white-marlin. Accessed 1 May 2024.