Legendary as one of the world’s greatest game fishes, Blue Marlin are also among the largest fish in the world with some females running well over 1,000 pounds.
Blue Marlin (Makaira nigricans)
(Florida Record 1046lbs.) The Blue Marlin is a large pelagic billfish that is named for the cobalt blue to blue-black color of its back. Like other billfish, the Blue Marlin has pigment-containing iridophores and light-reflecting skin cells that let it rapidly change color but it is most commonly seen with silvery-white sides and belly. There are about 15 rows of pale, cobalt-colored stripes that break up into round dots and thin bars running along both sides of the fish.
The Blue Marlin’s most distinguishing features are its long, stout bill and broad, deeply forked tail. In fact, the genus name for Blue Marlin, “Makaira” refers to the fish’s bill and is derived from the Greek and Latin words for sword or dagger. The Marlin’s bill, measured from eye to tip, constitutes about 20% of the total body length. The Blue Marlin has two dorsal fins and two anal fins, with the first dorsal fin being somewhat similar to a Sailfish dorsal fin but much smaller.
An interesting feature of the Blue Marlin is the ability of the long, narrow pectoral, caudal, and anal fins to fold down into grooves in the body to streamline the fish and reduce drag. This helps the fish reach its top speeds at around 50 miles per hour. Another unusual characteristic of the Blue Marlin is the great size of the females in comparison to the males. Females can reach 14 feet in length and weigh more than 1,400 pounds while males rarely exceed 350 pounds. Average sizes tend to be in the range of 6-8 feet and 200 to 400 pounds.
Blue Marlin Habitat and Behavior
Blue Marlin are found throughout tropical and subtropical oceans, with the Atlantic Blue Marlin being the species encountered in Florida Keys waters. It is a blue-water fish that spends most of its life in the open sea far from land and typically travels thousands of miles in its seasonal range. In the tropical Atlantic Ocean waters of the Northern and Southern Hemispheres, Blue Marlin live in a range that contracts towards the Equator during colder months. Warm currents such as the Gulf Stream have a major influence on the Marlin’s migration patterns. In the Keys, Blue Marlin can be found in mid-summer, but the best bite is in the fall from October through early November.
The Blue Marlin feeds near the surface on a wide variety of organisms. Mackerel, Tuna, and Squid are important prey items, and juvenile inshore fish will be taken by Marlin feeding near oceanic islands and coral reefs. Blue Marlin are known to take prey as large as White Marlin as well as Yellowfin and Bigeye Tuna in the 100-pound range, but they can also feed on small but numerous prey such as filefish and snipefish.
A Blue Marlin makes high-speed slashing attacks through schools of fish or other prey, using its bill to stun, injure, or kill fish then turning back to eat the wounded prey. A 2007 Japanese study of stomach contents from Blue Marlin caught by commercial trolling vessels found that almost half of the undigested prey items taken from 227 Blue Marlin had spearing, slashing, and other injuries that appeared to have been caused by the bill.
Fishing for Blue Marlin
Blue Marlin have been prized as sportfish since at least the 1920s and early 1930s when pioneering big-game fishermen encountered them offshore of Bimini and Cat Cay in the Bahamas. American authors and journalists Zane Grey and Ernest Hemingway wrote extensively about their experiences fishing for Blue Marlin off the Florida Keys, the Bahamas, and Cuba.
While not as prevalent as Sailfish, Blue Marlin can be found year-round in Key West waters. They are usually targeted southeast of Key West at a deep water bank known as Wood’s Wall, and there is a yearly tournament specializing in Marlin. Trolling orange and black lures or live baiting with big blue runners are two common ways to catch Key West Blue Marlin.
It is also typical to catch Blue Marlin while fishing for Mahi-mahi. The Marlin will show up and eat small “schoolie” Dolphinfish as they are being reeled in. A heavy rod set up with a 250 pound wind-on leader and a short 250 pound leader should be kept ready. When a Marlin is sighted, a small Dolphin is rigged as live bait and sight-cast to the hunting Marlin. A hookup results in a fight that can last for hours and leave even the toughest sportfisherman exhausted.