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 mazara) 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 mazara 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”.
Perception Channels: tactile ; chemical
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 mazara 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.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: no special status
In terms of absolute growth rate, M. mazara is one of the most rapidly growing teleosts during the early stages. The maximum growth rate of larvae can reach ~16mm/day.
Makaira mazara 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. mazara 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.
Positive Impacts: food ; ecotourism
The blue marlin occupies a high trophic level, feeding on pelegic and benthic organisms in the ecosystem of the open ocean.
(Gardieff, 2003)
Makaira mazara 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. mazara 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. mazara 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. mazara 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. mazara and are of appropriate size as prey for an adult blue marlin.
Makaira mazara 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.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Molluscivore )
Makaira mazara 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.
Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Makaira mazara 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.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: pelagic
The maximum lifespan of females is estimated to be at least 27 years, while males are estimated to live a maximum of 18 years.
Typical lifespan
Status: wild: 20 to 30 years.
Average lifespan
Status: wild: 20-30 years.
Makaira mazara 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. mazara 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 mazara 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.
Range mass: 748 (high) kg.
Average mass: 126-181 kg.
Range length: 455.8 (high) cm.
Average length: 200-300 cm.
Other Physical Features: heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Known Predators:
The spawning season extends from July through October in the North Atlantic. In the South Atlantic, M. mazara 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.
Breeding season: varies depending on geographic location
Average gestation period: 1 weeks.
Average age at sexual or reproductive maturity (female): 2-4 years.
Average age at sexual or reproductive maturity (male): 2-4 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
The eggs are bouyant in the water and drift until hatching with no parental care.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)
The Atlantic blue marlin (Makaira nigricans) is a species of marlin endemic to the Atlantic Ocean. It is closely related to, and usually considered conspecific with, the Indo-Pacific blue marlin, then simply called blue marlin. Some authorities consider both species distinct.
The Atlantic blue marlin (hereafter, blue marlin) feeds on a wide variety of organisms near the surface. It uses its bill to stun, injure, or kill while knifing through a school of fish or other prey, then returns to eat the injured or stunned fish. Marlin is a popular game fish. The relatively high fat content of its meat makes it commercially valuable in certain markets. It is the national fish of the Commonwealth of The Bahamas and is featured on its coat of arms.
Blue marlin are distributed throughout the tropical and subtropical waters of the Atlantic Ocean. A bluewater fish that spends the majority of its life in the open sea far from land,[2] the blue marlin preys on a wide variety of marine organisms, mostly near the surface, often using its bill to stun or injure its prey. Females can grow up to four times the weight of males. The maximum published weight is 818 kg (1,803 lb) and length 5 m (16.4 ft).[3] Greater lengths have been claimed unofficially.[4]
They are sought after as a highly prized game fish by anglers and are taken by commercial fishermen, both as a directed catch and as bycatch in major industrial tuna fisheries. Blue marlin are currently considered a threatened species by the IUCN due to overfishing,[1] particularly in the international waters off the coast of Portugal where they migrate to breed in the June/July months. Some other historic English names for the blue marlin are Cuban black marlin, ocean gar, and ocean guard.[5]
The blue marlin is placed in the genus Makaira. This name is derived from the Greek word machaira, meaning "a short sword or bent dagger", and the Latin machaera, "sword".[6][7] The specific epithet nigricans is Latin for "becoming black".[8] The blue marlin is part of the billfish family Istiophoridae and is in the perch-like order Perciformes. In addition, it is in the suborder Xiphioidei and is a member of the subclass Neopterygii, which means "new wings". It is also in the class of Actinopterygii, which includes ray-finned fishes and spiny-rayed fishes, and the superclass Osteichthyes, which includes all of the bony fishes.[9][10]
The classification of the Atlantic blue marlin (M. nigricans) and the Indo-Pacific blue marlin (M. mazara) as separate species is under debate. Genetic data suggest, although the two groups are isolated from each other, they are both the same species, with the only genetic exchange occurring when Indo-Pacific blue marlin migrate to and contribute genes to the Atlantic population.[11] A separate study by V. P. Buonaccorsi, J. R. Mcdowell, and Graves indicated that both Indo-Pacific and Atlantic show "striking phylogeographic partitioning" of mitochondrial and microsatellite loci.[12]
Synonyms of M. nigricans are:[3]
The biggest females are more than four times as heavy as the biggest males, which rarely exceed 160 kg (350 lb) in weight.[13] The longest females can reach a length of 5 m (16 ft) with the bill, from eye to tip, constituting about 20% of the total body length.
Body mass in the largest female specimens has been reported from 540 to 820 kg (1,190 to 1,810 lb), depending on the source (few large specimens are scientifically verified).[14] The largest blue marlin caught by IGFA angling rules is from Vitoria, Brazil, which weighed 1,402 lb (636 kg).;[15] fishermen often refer to individual marlins that reach or exceed 1,000 pounds as "granders".
Both sexes have 24 vertebrae, of which 11 are precaudal and 13 are caudal.[16]
The marlin has two dorsal fins and two anal fins. The fins are supported by bony spines known as rays. Its first dorsal fin has 39 to 43 rays from front to back.[16] Its second dorsal fin has six or seven rays.[16] Its first anal fin, which is similar in shape and size to the second dorsal fin, has 13 to 16 rays,[16] and the second anal fin has six or seven rays.[16] The pectoral fins, which have 19 to 22 rays,[16] are long and narrow and can be drawn in to the sides of the body. The pelvic fins are shorter than the pectorals, have a poorly developed membrane, and are depressible into ventral grooves. Its first anal fin, along with its pectoral and caudal fins, can be folded into grooves. This streamlines the fish and thereby reduces drag.
Blue marlin, like other billfish, can rapidly change color, an effect created by pigment-containing iridophores and light-reflecting skin cells.[17]
Most often, however, the body is blue-black on top with a silvery white underside. It has about 15 rows of pale, cobalt-colored stripes, each of which has round dots and/or thin bars, located on both sides of the fish.[16] The first dorsal fin membrane is dark blue or almost black and has no dots or marks. Other fins are normally brownish-black, sometimes with a hint of dark blue. The bases of the first and second anal fins have a hint of silvery white.
The body is covered with thick, bony, elongated scales that have one, two, or three posterior points, with one being the most common form.[16]
The bill is long and stout. Both the jaws and the palatines (the roof of the mouth) are covered with small, file-like teeth. The lateral line system is a group of neuromasts rooted in lateral line canals that can sense weak water motions and large changes in pressure.[18] It has the appearance of a net.[19] It is obvious in immature specimens but unclear in adults, becoming progressively embedded in the skin.[16] The anus is just in front of the origin of the first anal fin.
Blue marlin are found year-round in tropical oceanic waters of the Atlantic. The range expands into temperate waters of the Northern and Southern Hemispheres during the warmer months and contracts towards the Equator during colder months.[20] Warm currents such as the Gulf Stream in the western Atlantic have a major influence on their seasonal distribution.
Being the most tropic of all the billfishes, they spend a lot of time in the water column shifting from the top to a depth of 100 meters. They spend most nights near the surface and dive to deeper depths during the day. Limited from going any lower by the water temperature and oxygen levels. [21]
The blue marlin's latitudinal range extends from about 45°N to about 35°S. It is less abundant in the eastern Atlantic, where it mostly occurs off Africa between the latitudes of 25°N and 25°S. The largest numbers are usually found in waters warmer than 24 °C (75 °F), but blue marlin have been found at surface water temperatures as high as 30.5 °C (86.9 °F) and as low as 21.7 °C (71.1 °F).[22]
Tagging studies, using conventional "spaghetti" tags, and more recently pop-up satellite tags, have given researchers a glimpse into blue marlin migration patterns and habits. Recaptures of tagged fish have shown multiple movements between the Caribbean Islands and Venezuela and the Bahamas, as well as between the Caribbean Saint Thomas, U.S. Virgin Islands and West Africa, and interocean travel. Most notably, a blue marlin tagged off the coast of Delaware was recovered near the island of Mauritius off the southeast coast of Africa in the Indian Ocean – a voyage of 9,254 miles.[23] Several fish have been recaptured in the same general area where they were tagged, implying reverse migration after/over several years, but the data are insufficient to accurately determine seasonality.[24]
Once blue marlin reach maturity, they have few predators, with the most important being killer whales and large pelagic sharks such as the shortfin mako and great white shark.[25]
Blue marlin have many parasites, including from these groups: Digenea (flukes), Didymozoidea (tissue flukes), Monogenea (gillworms), Cestoda (tapeworms), Nematoda (roundworms), Acanthocephala (spiny-headed worms), copepods, barnacles, and cookiecutter sharks.
Growth and maturity
Atlantic blue marlin reach sexual maturity at the age of two to four years. Males reach sexual maturity at a weight of 35–44 kg (77–97 lb) and females at 47–61 kg (104–134 lb).[26] Blue marlin breed in late summer and fall. Females may spawn as many as four times in one season. They often release over seven million eggs at once, each about 1 mm (0.039 in) in diameter. Few reach sexual maturity. The planktonic young drift freely in the ocean's pelagic zone. Larvae inhabit the west central Atlantic off the Southern United States, Jamaica, The Bahamas, the Dominican Republic, and Puerto Rico, and also the southwest Atlantic off Brazil.[13] The larvae may grow as much as 16 mm (0.63 in) in a day.[13] On their sides and dorsal surfaces, they are blue-black in color, while ventrally they are white. Both the caudal fin and the caudal peduncle (the narrow part of the fish's body to which the caudal or tail fin is attached) are clear. Two iridescent blue patches occur on the head, and some individuals have darker spots on their backs. In adolescents, the first dorsal fin is large and concave, gradually reducing in proportion to body size with continued growth.[5] Males may live for 18 years, and females up to 27.
Diet and feeding
The larvae feed upon a variety of zooplankton along with drifting fish eggs and other larvae. They progress to feeding on a wide range of fishes, particularly scombrids, such as mackerel and tuna, squid, and especially near oceanic islands and coral reefs, on juvenile inshore fish. Studies of stomach contents have found that smaller schooling scombrids such as frigate mackerel, bullet tuna, and skipjack tuna make up a substantial proportion of their diet. Squid and deep-sea fishes such as pomfret and snake mackerel are also important prey items in certain areas. Blue marlin have been recorded to take prey as large as white marlin, as well as yellowfin and bigeye tuna in the 100-lb range. Conversely, they are also capable of feeding on small but numerous prey such as filefish and snipefish.
Scientists and fishermen have long debated the extent to which blue marlin and other billfish use their elongated upper jaw in feeding. A 2007 Japanese study of stomach contents of fish captured in a commercial trolling fishery found that 130 undigested prey items obtained from 227 blue marlin had spearing, slashing, and other injuries that were judged to have been inflicted by the bill.[27]
Bioaccumulation
Heavy metals have been known to accumulate in the Atlantic blue marlin, a process known as bioaccumulation. In 2017, the Texas Parks and Wildlife Department issued a consumption advisory for all blue marlin caught along the coast of Texas based on the presence of mercury.[28]
Marlin has commercial value throughout the world, with landings totalling 3,064 metric tons in 2000.[13] It is particularly valued in Japan for sashimi.[13] Blue marlin meat is sometimes smoked and sold by roadside vendors.
Blue marlin are often caught as bycatch in tuna longline fisheries.
Sport fishermen first encountered blue marlin in the Bahamas in the 1920s and early 1930s, when pioneering big-game fishermen such as Van Campen Heilner and S. Kip Farrington began exploring the waters offshore of Bimini and Cat Cay. Since then, blue marlin have been renowned as one of the world's greatest game fishes. The sportfishing pursuit of marlin and other billfish has developed into a multimillion dollar industry that includes hundreds of companies and thousands of jobs for boat operators, boat builders, marinas, dealerships, and fishing tackle manufacturers and dealers.
The most established sport fisheries for blue marlin are found along the eastern seaboard and the Gulf Coast of the United States, Bermuda, the Bahamas, and several other Caribbean islands (notably St Thomas and Puerto Rico). Recreational fishing for blue marlin also takes place in Hawaii, Brazil, Venezuela, and the Atlantic coast of Mexico, particularly the Yucatan peninsula. In the eastern Atlantic, blue marlin sport fisheries exist from the Algarve coast of Portugal in the north to Angola in the south and include the islands of the Azores, Canaries, Cape Verde, Madeira, and Ascension Island.
The International Game Fish Association all-tackle world record for blue marlin currently stands at 1,402 lb 2 oz (636 kg).[5] This fish was captured in Vitoria, Brazil.
The blue marlin is under intense pressure from longline fishing. In the Caribbean region alone, Japanese and Cuban fishermen annually take over a thousand tons. All vessels within 200 mi (320 km) of the U.S. coastline are required to release any billfish caught. However, the survival rate of released fish is low because of damage during capture.[5]
Makaira nigricans is listed as a threatened species by the International Union for Conservation of Nature.[1] In 2010, Greenpeace International added the blue marlin to its seafood red list. [29]
Sport fishermen have been at the forefront of efforts to conserve blue marlin populations. The initial efforts to develop electronic tags for tracking highly migratory fish were carried out on marlin in Hawaii, in collaboration with anglers in the Hawaiian International Billfish Tournament.[23]
Both Zane Grey and Ernest Hemingway, who fished for blue marlin off the Florida Keys, The Bahamas, and most famously in Cuba, wrote extensively about their pursuit.
The blue marlin is featured prominently on the obverse of the 5 Bermudian dollar note.
In Hemingway's novella The Old Man and the Sea, a fisherman named Santiago battles a blue marlin for three days off the coast of Cuba.[2][30]
The Atlantic blue marlin (Makaira nigricans) is a species of marlin endemic to the Atlantic Ocean. It is closely related to, and usually considered conspecific with, the Indo-Pacific blue marlin, then simply called blue marlin. Some authorities consider both species distinct.
The Atlantic blue marlin (hereafter, blue marlin) feeds on a wide variety of organisms near the surface. It uses its bill to stun, injure, or kill while knifing through a school of fish or other prey, then returns to eat the injured or stunned fish. Marlin is a popular game fish. The relatively high fat content of its meat makes it commercially valuable in certain markets. It is the national fish of the Commonwealth of The Bahamas and is featured on its coat of arms.
Blue marlin are distributed throughout the tropical and subtropical waters of the Atlantic Ocean. A bluewater fish that spends the majority of its life in the open sea far from land, the blue marlin preys on a wide variety of marine organisms, mostly near the surface, often using its bill to stun or injure its prey. Females can grow up to four times the weight of males. The maximum published weight is 818 kg (1,803 lb) and length 5 m (16.4 ft). Greater lengths have been claimed unofficially.
They are sought after as a highly prized game fish by anglers and are taken by commercial fishermen, both as a directed catch and as bycatch in major industrial tuna fisheries. Blue marlin are currently considered a threatened species by the IUCN due to overfishing, particularly in the international waters off the coast of Portugal where they migrate to breed in the June/July months. Some other historic English names for the blue marlin are Cuban black marlin, ocean gar, and ocean guard.
