Makaira nigricans is distributed mainly in the tropical and temperate waters of the Atlantic, Pacific, and Indian Oceans. It is the most tropical of all billfishes.
In the Atlantic Ocean, its range extends to around 40-45N in the North Atlantic and to 40S in the western Atlantic, 30S in the central South Atlantic and 35S in the eastern south Atlantic, but is absent from the Mediterranean Sea. In the Pacific, its range extends to about 45N in the western North Pacific, 35N in the eastern North Pacific, 35S in the western South Pacific, and 25S in the eastern South Pacific. In the Indian Ocean, its range extends to 45S in the southwestern Indian Ocean and 35S in the southeastern Indian Ocean.
Larvae are found extensively in the tropical and subtropical waters of the western and central Pacific Ocean, south of Maldives Islands, around the Mascalene Islands, and off the south coasts of Java and Sumatra in the Indian Ocean. In the western central Atlantic, larvae are found off Georgia, North Carolina, Florida, Jamaica, Bahamas, Arecibo, and also off Brazil in the southwest Atlantic. (Nakamura, 1985)
Makaira nigricans is an epipelagic and oceanic species. It is the most oceanic of all istiophorids, usually remaining far from land except where the continental shelf is narrow. It can be found in waters with surface temperatures of 22-31C, but it prefers the warm mixed layer above the thermocline, and spends the majority of its time in the uniformly warm near-surface waters from 25-27C. It shows preference for blue waters, at least in the northern Gulf of Mexico. (Block, et al., 1992a; Block, et al., 1992b; deSylva and Breder, 1997; Nakamura, 1985)
Makaira nigricans possesses a long bill that is very stout and round in cross section, with a conspicuous elevated nape (the part of neck posterior to the head). Small, file-like teeth line both jaws and the roof of its mouth. It has two dorsal fins, and two anal fins. The body is densely covered with elongated, thick bony scales, each with mostly 1 or 2, sometimes 3 posterior points. Body coloration is blue black on the dorsal side and silvery white on the ventral side, with approximately 15 rows of pale cobalt-colored strips made up of round dots and/or narrow bars running down both sides of the body. The first dorsal fin is blackish or dark blue, while the other fins are usually dark brown, sometimes tinged with dark blue. The bases of the anal fins are tinged silvery white.
When swimming rapidly, M. nigricans can fold its first dorsal, first anal, and pectoral fins down into fin grooves on the body to increase streamlining. In contrast, the pectoral fins of its near relative, Makaira indica (black marlin), are rigid and cannot be folded back against its body.
Makaira nigricans is one of the largest fish in the world. Weight averages between 126 kg and 181 kg. Length averages from about 200 to 300 cm lower jaw fork length (LJFL), which is measured from the tip of the lower jaw to the posterior margin of the middle caudal ray. The largest male recorded in the scientific literature is 170.3 kg, 263.1 cm LJFT, while the largest female is 748.0kg, 445.8 cm LJFT.
Sexual dimorphism is exhibited in weight, where the females are typically heavier than males. Weight dimorphism begins at 140 cm LJFL when the females start growing at a faster rate than the males. Females usually grow to at least 540 kg, while males seldom exceed 160kg. (Nakamura, 1985; Wilson, et al., 1991)
The spawning season extends from July through October in the North Atlantic. In the South Atlantic, M. nigricans exhibits fall spawning when the sea surface temperature is at 28C. In the Pacific Ocean, spawning occurs from December to January during the southern hemisphere’s summer. Females can spawn up to four times during the reproductive season, while males can spawn year round.
Sexual maturity is reached at 2-4 years of age. Females reach sexual maturity at 120kg or below. The smallest mature female recorded weighs 45kg. Fecundity of a female at 124 kg is estimated to be 7 million eggs, and 10.9 million eggs for a female of 147kg. Eggs are spherical, transparent, white to yellow in color, and around 1mm in diameter. (Bartlett and Haedrich, 1968; deSylva and Breder, 1997; Erdman, 1968; Kume and Joseph, 1969; Nakamura, 1985)
The eggs are bouyant in the water and drift until hatching with no parental care. (Nakamura, 1985)
The maximum lifespan of females is estimated to be at least 27 years, while males are estimated to live a maximum of 18 years. (Hill, et al., 1989)
Makaira nigricans is rare and primarily solitary, in contrast to the other schooling scrombids. It is highly migratory, and has exhibited transequatorial and transatlantic movements. Evidence from The Cooperative Game Fish Tagging Program in the western North Atlantic demonstrated two-way, seasonal movements between the Caribbean Islands, Venezuela and the Bahamas, and at least one-way travel from St. Thomas at the U.S. Virgin Island to the Ivory Coast of West Africa (7,000 km). Makaira nigricans also engages in a daily cycle of vertical migration, swimming deeper in the day and closer to the surface at night.
Makaira nigricans is a subcarangiform swimmer that propels itself with its caudal fin and displaces water with side to side undulatory movements, similar to a shark. It follows a straight or slightly curving course when swimming. Typically, it travels at low speeds of around 2-3km/h for long periods, which are punctuated by short bursts of rapid speed associated with descents down the water column. The fastest speed measured by a speedmometer is 225cm/s, though it has been observed to attack fish bait trawled at 800cm/s. As a continuous swimmer, it can cover 40-70 km in a day. (Block, et al., 1992a; Block, et al., 1992b; Hebrank, et al., 1990; Holland, et al., 1990; Witzell and Scott, 1990)
Makaira nigricans is an apex predator. Often, it approaches a school of fish or invertebrates at full speed, slashes through with its bill, then returns to devour the stunned or dead prey. It forages mostly in the near-surface waters, but the presence of benthic and demersal species in its stomach indicates it also feeds near the bottom. It consumes a large variety of prey species of different sizes and morphology from various trophic levels. But it also disproportionately targets a few species. This indicates that M. nigricans is a specialized but opportunistic feeder, a foraging mode suited to the warm water oceans where food is unevenly distributed.
The numbers and types of species consumed vary, depending on the location and season. For instance, M. nigricans feeds mainly on bullet mackerel (Auxis spp.) off the coast of Mexico, and on shipjack tuna (Kutsuwonus pelamis) in the central Pacific. Fish is the most frequent prey, and can constitute up to 86% of the total volume of food consumed by M. nigricans in Hawaii. Scrombidae, especially tuna-like species, are consistently the most important prey items, among which shipjack tuna (K. pelamis) and frigate mackerel (Auxis thazard) are the most common. Tuna-like species are abundant, co-occur over the geographic range and epipelagic habitat of M. nigricans and are of appropriate size as prey for an adult blue marlin.
Makaira nigricans also feeds on a small amount of inshore juvenile fish, among which Balistidae and Acanthuridae are more common. Among the cephalopods that are consumed, squids from the family Ommastrephidae are commonly consumed, along with many other kinds of squids. (Abitia-Cardenas, et al., 2000; Baker, 1966; Block, et al., 1992b; Brock, 1984; Erdman, 1962; Nakamura, 1985; Royce, 1957; Strasburg, 1970)
The blue marlin occupies a high trophic level, feeding on pelegic and benthic organisms in the ecosystem of the open ocean.
Makaira nigricans is usually caught as bycatch in tuna longline fisheries but has some commercial value throughout the world. In 2000, blue marlin landings totaled 25717 metric tons in the Pacific and 3064 metric tons in the Atlantic. The countries with the largest landings are Taiwan, China (13618 mt) and Japan (7899 mt). Other countries with blue marlin captures include Ghana, Brazil, Cote divoire, and South Korea. Blue marlin flesh is of excellent quality. It is especially valuable in Japan, where flesh with high fat content is used raw for sashimi.
Due to its rarity, large size, legendary speed, and powerful aerobics on rod and reel, M. nigricans is a popular and prestigious catch for recreational fishermen. In fact, an entire multi-million dollar industry has evolved around this “rare event” species. Sport fisheries are especially developed in the U.S., Venezuela, Bahamas, Brazil, the Caribbean, and along the coast of West Africa. (FAO, 2002; ICCAT, October 2002; Witzell and Scott, 1990)
The blue marlin stock in the Atlantic has probably been overfished for the last 10-15 years. Its maximum sustained yield is estimated to be 2000 metric tons, so the stock is being depleted faster that it can replenish itself at landings of 3064 metric tons in 2000. The predominant blue marlin landings occur as bycatch in offshore longline fisheries that target tropical and temperate tunas by fishing shallow, and to a lesser degree in offshore longline fisheries and drift nets targeting swordfish and bigeye tuna by fishing deep.
Due to their migratory nature, wide geographic range, and multinational fishing pressure, it is difficult to manage and set up regulations to protect the blue marlin stock.
The International Commission for the Conservation of Atlantic Tunas (ICCAT) is a major international organization with 32 contracting countries aiming to conserve tunas and tuna-like species in the Atlantic Ocean and adjacent seas. Makaira nigricans is one of the 30 species of direct concern to ICCAT. The Commission has recommended that the blue marlin landings of pelagic longlines and purse seine vessels be reduced to at most 50% of the 1996 or 1999 level, whichever is greater. In the US, the NMFS has imposed a size limit of 251cm LJFL on the recreational blue marlin catch, and has prohibited commercial fishermen from fishing, taking, or retaining blue marlin. (Block, et al., 1992a; FAO, 2002; ICCAT, October 2002)
There is an ongoing disagreement on whether blue marlin populations in the Atlantic and Indo-pacific regions are distinct species. Some consider them to be a single pantropical species occurring in the Atlantic, Pacific and Indian Ocean. Others consider them to be two distinct species, namely the Atlantic blue marlin (Makaira nigricans) and Indo-Pacific blue marlin (Makaira mazara), due to their different lateral line patterns. Lateral line is a series of organs enclosed in tubular scales along the side of the body of a fish. Blue marlin in the Atlantic have a reticulate, complicated network of lateral line patterns, while Pacific blue marlin have single looped patterns. The presence of identical haplotypes in blue marlin samples from the Atlantic and Pacific suggests that they should be considered a single species.
Makaira nigricans is the giant monster the “old man” battled with for three days and nights non-stop in Ernest Hemingway’s classic “The Old Man and the Sea”. (Graves and McDowell, 1995; Nakamura, 1985)
William Fink (editor), University of Michigan-Ann Arbor.
Luana Tung (author), University of Michigan-Ann Arbor.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
fertilization takes place outside the female's body
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
an animal that mainly eats fish
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
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