Blue marlin
| Blue marlin | ||||||||||||
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Blue marlin jumping out of the water |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Makaira | ||||||||||||
| Lacepède , 1802 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Makaira nigricans | ||||||||||||
| Lacepède, 1802 |
The blue marlin ( Makaira nigricans , from Latin nigricans , blackish, dark) is a large predatory fish that lives in the Atlantic and Indo-Pacific. It lives in the open ocean, comes little near the coast and feeds on other fish and cephalopods .
distribution
Of all spearfishes, the blue marlin is most tied to a tropical climate, occurs primarily in tropical and subtropical areas of the Atlantic and, judging by the number of catches in the fishery, is more common in the warmer western Atlantic than in the eastern Atlantic. Its distribution area extends in the northern Atlantic from 40 ° to 45 ° north latitude to 40 ° south latitude in the western South Atlantic, 30 ° S in the central South Atlantic and 35 ° S in the eastern South Atlantic. The fish live off the coast of Africa mainly between 25 ° N and 25 ° S. Since he can heat up his eyes and brain, occasional forays into cooler waters (<21 ° C) do not cause him any difficulties.
features
The blue marlin has an elongated, laterally only slightly flattened body. It is covered by thick, elongated scales, which are sunk deep into the skin, usually with only one rear point, sometimes with two, rarely with three points. The sword is long, thick at the base, and round in cross-section. The head profile is steep, the body is at the front, directly behind the head, highest and sloping more and more towards the back. The first of the two dorsal fins is long and extends over most of the length of the body. Its first section, which towers to a point, is high, but always lower than the height of the body. It begins above the rear edge of the gill cover , extends to just before the second dorsal fin and is supported by 39 to 43 fin rays. The second dorsal fin has six to seven fin rays and is symmetrical to the second anal fin , which has the same number of fin rays. The larger first anal fin has 13 to 16 fin rays. The anus is located just before the first anal fin. The sickle-shaped pectoral fins are supported by 19 to 22 fin rays. They can be placed very close to the body. The slightly shorter, rod-shaped pelvic fins are very close and can be inserted into a furrow. Your fin membrane is only slightly developed. The caudal fin stalk is flattened on the sides and has two strong cartilaginous keels on each side for stabilization. All fin rays are unsegmented and not articulated. The swimming style of the marlin is carangiform (tail compress).
The blue marlin has 24 vertebrae, eleven of which are in front of the anus and 13 are caudal vertebrae. There are tiny teeth on the jaw, palate and vomer . The Branchiostegalmembranen have grown together completely. Gill trap rays are absent. The skeleton shows a scleral bone covering around the eye, which is not deformed even under heavy stress from fast swimming. The sideline system forms a wire mesh-like network, which is clearly visible in not yet sexually mature animals, but is increasingly covered by skin in older marlins and is only visible in fully-grown animals when the epidermis is removed.
The blue marlin can be up to 3.75 meters long and weighs 580 kg. The length of the animals caught in longline fishing is usually between 2.30 and 3.45 meters, of which 2.0 to 2.75 is the body length. Deep sea anglers also reported catching 680 kg marlins. The highest weight confirmed by the International Game Fish Association was 581.51 kg, the second heaviest specimen weighed 461.98 kg.
The back is black-blue, the belly white-silver. On the back there are 15 narrow, cobalt blue ribbons, which are composed of round dots or narrow stripes, the contrast of which depends on the mood. The dorsal fin is dark blue to black without points or other markings. The remaining fins are more brown-black with a blue sheen in some individuals, the anal fins are silvery white at the base.
hikes
The blue marlin is a species that lives in the epipelagic (the upper 200 meters) of the open oceans. The heat-loving fish prefer water temperatures between 22 and 31 ° C. In contrast to the sailfish ( Istiophorus albicans ) it rarely forms schools and mostly lives as a loner. There seems to be a connection between the color of the water and the occurrence of the widely migratory species, at least in the northern Gulf of Mexico it is mainly observed in blue water. In the western Atlantic, most fish are between 5 ° and 30 ° S from January to April and between 10 ° and 35 ° N from June to October. In May, November and December the animals seem to migrate. In the northern Gulf of Mexico, anglers most often catch the blue marlin when the catches of the white marlin ( Kajikia albida ) are lowest and vice versa.
nutrition
The blue marlin mainly hunts near the surface of the sea. He preyed on other large, fast-swimming predatory fish, such as golden mackerel , mackerel and tuna-like fish such as bonitos . The size of the prey fish is between 20 cm and one meter, that of the captured cephalopods between 15 cm and 60 cm. Stomach examinations revealed an 11 kg squid in an Atlantic blue marlin weighing around 135 kg, while a 290 kg animal caught in the Gulf of Guinea had swallowed a 50 kg bigeye tuna . The discovery of deep-sea fish such as Pseudoscopelus in the stomachs of marlins shows that they occasionally go to greater water depths to catch their prey. They avoid the night hours and seem to prefer the morning.
Reproduction
The breeding time and the spawning grounds of the marlin are poorly known. Sexual maturity occurs at the age of two to four years. A female can spawn four times in one season, while a 124 kg female can shed up to seven million eggs. In the North Atlantic, they spawn from July to October. So far only larvae and juvenile fish have been caught off the coast of the southeastern USA and in the Caribbean. The eggs of the fish are transparent, whitish to yellow and have a diameter of one millimeter.
Systematics
The blue marlin belongs to the spearfish family (Istiophoridae), which also includes the sailfish ( Istiophorus platypterus ) and other marlin and marlin species. The spearfishes differ from their relatives, the swordfish , in a number of characteristics : the latter have a flattened sword that is sharp on the sides, while the spearfish has a round cross-section. In addition, swordfish lack teeth, pelvic fins, pelvis and a keel on each side of the tail stem - fanfish and spearfish, on the other hand, have two keels per side. In addition to Makaira nigricans , the Indo-Pacific blue marlin ( Makaira mazara (Jordan & Snyder 1901)) has also been described. Both species differ only in the pattern of the lateral line system, which is simpler in the Indo-Pacific species, and are otherwise so similar that scientists increasingly only recognize Makaira nigricans as a pantropical species and make Makaira mazara a synonym for the first. At the genetic level, too, no differences have been found that would justify a separation into two species. The blue marlins are the sister group of the sailfish. Together with this they are the sister group of all other marlin and spearfish.
A by analysis of mitochondrial - DNA and the principle of maximum parsimony Calculated cladogram showing the relationships of all swordfish-like (Xiphioidei (Istiophoridae and Xiphidae)):
| Xiphioidei |
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fishing
The blue marlin has excellent meat and is a valued food fish. Long lines, harpoons and nets are used for fishing. Because of its size and wildness, it is a coveted trophy for deep sea anglers. When trying to break free from the line, the marlin engages in a protracted fight and shoots out of the water in spectacular leaps.
Culture
The blue marlin is also the fish that Ernest Hemingway immortalized in the novel The Old Man and the Sea in 1951 .
literature
- Izumi Nakamura: FAO Species Catalog An Annotated and Illustrated Catalog of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date. Rome 1985, ISBN 92-5-102232-1 online
Web links
- Blue Marlin on Fishbase.org (English)
- Tung, L. 2003. Makaira nigricans Animal Diversity Web.
- Makaira nigricans onthe IUCN 2013 Red List of Threatened Species . Posted by: Collette, B., Acero, A., Amorim, AF, Boustany, A., Canales Ramirez, C., Cardenas, G., Carpenter, KE, de Oliveira Leite Jr., N., Di Natale, A ., Die, D., Fox, W., Fredou, FL, Graves, J., Guzman-Mora, A., Viera Hazin, FH, Hinton, M., Juan Jorda, M., Minte Vera, C., Miyabe, N., Montano Cruz, R., Nelson, R., Oxenford, H., Restrepo, V., Salas, E., Schaefer, K., Schratwieser, J., Serra, R., Sun, C. , Teixeira Lessa, RP, Pires Ferreira Travassos, PE, Uozumi, Y. & Yanez, E., 2009. Retrieved February 4, 2014.
Individual evidence
- ↑ B. A. Block, J. R. Finnerty, A. L. Stewart and J. Kidd: Evolution of endothermy in fish: mapping physiological traits on a molecular phylogeny. Science 1993 260: 210-214.
- ↑ a b Bruce B. Collette, Jan R. McDowell, John E. Grawe: Phylogeny of recent Bill Fishes (Xiphioidei). Bulletin of Marine Science: 79 (3), 455-468, 2006