Sailfish
| Sailfish | ||||||||||||
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Sailfish ( Istiophorus platypterus ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Istiophorus | ||||||||||||
| Lacepède , 1801 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Istiophorus platypterus | ||||||||||||
| ( Shaw , 1792) |
The Sailfish ( Istiophorus platypterus ), often sailfish called, is a large, living in the open ocean predator that grows in the tropical and subtropical regions almost worldwide.
In addition to Istiophorus platypterus , another Istiophorus species has been described, the "Atlantic sailfish", Istiophorus albicans (Latreille, 1804). However, both species are so similar that science increasingly only recognizes Istiophorus platypterus and makes Istiophorus albicans a synonym for the first. At the genetic level, too, no differences have been found that would justify a separation into two species.
features
The unmistakable characteristic of the sailfish, which can also be recognized from a boat in a fish swimming close to the sea surface, is the large, sail-like first dorsal fin, which is higher than the fish's body at its highest point. The body of the sailfish is elongated and strongly flattened on the sides. They usually reach lengths of around 2.5 meters. The maximum length stated is 3.80 meters. The fish reach a weight of 50 to 100 kg. Very large specimens are always females. Sailfish can supposedly reach top speeds of 40 to 59 knots (approx. 75–110 km / h) and are therefore considered to be the fastest fish. More recent studies, however, strongly question this information, according to which fan fish do not exceed speeds of 36 km / h. A new study shows that the theoretically maximum expected maximum speed is 36 to 45 km / h.
The top of the fish is dark blue, the flanks light blue with brown color markings and about 20 vertical stripes composed of many light blue dots. The belly and the base of the first and second anal fin are silvery white. The membrane of the large first dorsal fin is dark blue or almost black with isolated small, round, black dots. The remaining fins are blackish brown or dark blue.
The sword-like elongated rostrum is, as with all istiophores and in contrast to the swordfish , round in cross-section. The jaw and palatine bone of adult animals are covered with small teeth. Gill trap rays are missing, the right and left Branchiostegal membranes have grown together. The sailfish uses its rostrum to catch fish by striking horizontally or by gently bumping into individual fish and throwing them off balance.
Of the two dorsal fins, the first is very large, with a long fin base that extends from the rear edge of the head to almost the second dorsal fin on the tail fin stalk. It is supported by 42 to 49 (maximum 46 in I. albicans ) fin rays. The second, much smaller dorsal fin has seven to eight fin rays. The large dorsal fin plays an important role in fishing as it stabilizes the head (much like the keel of a boat) before the sailfish hits a blow with its rostrum.
The first of the two small anal fins is supported by twelve to 17 fin rays (eleven to 14 in I. albicans ), the second is six to seven. The second anal fin starts a little further forward than the second dorsal fin. The anus is close to the beginning of the first anal fin.
The pelvic fins are very long and reach the anus. When swimming quickly, they can be placed in a pit and are supported by a hard beam and two to three soft beams that have grown together. The pectoral fins have 18 to 20 fin rays. In immature specimens (from 90 cm in length) they are longer in I. albicans relative to body length than in I. platypterus . The tail fin stalk is double keeled on both sides and has a flat notch on the back and the belly side. Both tail fin parts are sickle-shaped.
Sailfish have a single, clearly visible sideline . The scales take on a different shape as they grow. Those of the adults have a single, rather blunt point and two posterior ends. They are completely embedded in the skin. The number of vertebrae is 24 (twelve precaudal vertebrae and twelve vertebrae in the caudal spine).
distribution
The sailfish occurs in the western Pacific from 45 ° to 50 ° north latitude and 40 ° to 35 ° south latitude and in the cooler eastern Pacific between 35 ° N and 35 ° S. In the western Indian Ocean the distribution area extends north of the 45 ° south latitude, in the east north of the 35 ° south latitude. In the north, the range is limited by the coast of South Asia. The fish also live in the Red Sea and migrate into the Mediterranean through the Suez Canal .
In the Atlantic, the Atlantic sailfish population occurs between 40 ° north latitude in the northwest and 50 ° north latitude in the northeast and 40 ° S in the south-west and 32 ° S in the south-west. In addition to the Mediterranean Sea, both sailfish populations only have contact with one another and can mix on the coast of South Africa .
Sailfish prefer water that is between 21 and 28 ° C and mainly stay above the thermocline , but can also dive deeper.
Way of life
Sailfish live pelagically at depths of 200 meters to the surface of the sea. They undertake long hikes and often stay near the coast or near islands. Specimens of the same size form schools of up to 30 individuals or loose collections over a larger region. Sailfish often hunt in groups that can contain up to 70 animals. When attacking a school of fish, an average of two prey fish are injured with the rostrum, but only every fifth attack leads to a successful catch. Over time, more and more fish are injured and are therefore easier to catch.
Most of the time the sailfish take turns attacking schools of fish. While a sailfish is waiting to be attacked, other sailfish are already injuring fish in the school and favor the success of their next attack. The hunt in the group thus creates an efficiency advantage for the members and one speaks therefore of protocooperation.
nutrition
Sailfish feed on smaller pelagic fish, crustaceans, or squids . Among the prey fish are sardines , halfbeak pike , mackerel , cutlassfish , trevally , sea bream and gurnard . Even paper boats are consumed. Underwater observations show that the sailfish shoot into schools of fish at full speed with their ventral fins attached, then brake with a sharp curve and spread ventral fins and kill fish within reach with quick sword strokes and then eat them head first. Often several individuals show some kind of team behavior and work together on the hunt. They also form feeding communities with other large marine predators such as dolphins , sharks , marlins , tuna and golden mackerel .
Small sailfish larvae mainly feed on copepods , but as they grow in size, the diet is quickly switched to fish larvae and very small fish only a few millimeters in length.
Reproduction
Sailfish show no external sex difference. The largest specimens are always female. Reproduction occurs mostly during the local summer, but can also occur all year round. They spawn in shallow water near the coast, in pairs or a female with two or three males. A lot of eggs are released. In a 33.4 kg female, 4.8 million eggs were found to mature in three groups in succession in the ovaries, so that the female spawns three times during the breeding season of one year. The ripe eggs are 0.85 to 1.3 mm in diameter. They are translucent with no structure on the yolk and contain a drop of oil that keeps them suspended in the water. The larvae are also pelagic.
External system
Sailfish belong to the Istiophoridae family , which also includes marlins and marlins. They differ from the swordfish , which have a flattened sword that is sharp on the sides and no ventral fins, by the ventral fins and the sword, which is round in cross section. The sailfish are the sister group of the blue marlin ( Makaira nigricans ). Together they are the sister group of all other marlin and spearfishes. A by analysis of mitochondrial - DNA and the principle of maximum parsimony Calculated cladogram showing the relationships of all Xiphioidei (Istiophoridae and Xiphidae):
| Xiphioidei |
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use
Sailfish are an attractive trophy for deep sea anglers . Their meat is prepared in a variety of ways and is also used for sashimi and sushi .
swell
literature
- Izumi Nakamura: FAO Species Catalog An Annotated and Illustrated Catalog of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date. ISBN 92-5-102232-1 online
Web links
- Sailfish on Fishbase.org (English)
- Istiophorus platypterus inthe 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., 2010. Retrieved February 4, 2014.
Individual evidence
- ↑ a b Bruce B. Collette, Jan R. McDowell, John E. Grawe: Phylogeny of recent Bill Fishes (Xiphioidei). In: Bulletin of Marine Science. 79 (3), 2006, pp. 455-468.
- ↑ Istiophorus platypterus on Fishbase.org (English)
- ↑ Kurt Fiedler: Textbook of Special Zoology. Volume II, Part 2: Fish. Gustav Fischer Verlag, Jena 1991, ISBN 3-334-00339-6 , p. 390.
- ↑ Sailfish, Istiophorus platypterus. Retrieved January 5, 2013 .
- ↑ academic.oup.com
- ↑ MBS Svendsen, P. Domenici, S. Marras, J. Krause, KM Boswell, I. Rodriguez-Pinto, ADM Wilson, RHJM Kurvers, PE Viblanc, JS Finger, JF Steffensen: Maximum swimming speeds of sailfish and other large marine predatory fish species based on muscle contraction time: A myth revisited. In: Biology Open. 5, 2016, pp. 1415-1419. (bio.biologists.org)
- ↑ a b P. Domenici, ADM Wilson, RHJM Kurvers, S. Marras, JE Herbert-Read, JF Steffensen, S. Krause, PE Viblanc, P. Couillaud, J. Krause: How sailfish use their bill to capture schooling prey. In: Proceedings of the Royal Society London. B 281, 2014, p. 20140444. (rspb.royalsocietypublishing.org)
- ↑ a b c J. E. Herbert-Read, P. Romanczuk, S. Krause, D. Strömbom, P. Couillaud, P. Domenici, RHJM Kurvers, S. Marras, JF Steffensen, ADM Wilson, J. Krause: Group hunting sailfish alternate their attacks on their grouping prey to facilitate hunting success. In: Proceedings of the Royal Society London. B 283, 2016, S. 20161671. (rspb.royalsocietypublishing.org)
- ↑ S. Marras, T. Noda, JF Steffensen, MBS Svendsen, J. Krause, ADM Wilson, RHJM Kurvers, J. Herbert-Read, P. Domenic: Not so fast: swimming behavior of sailfish during predator-prey interactions using high -speed video and accelerometry. In: Integrative and Comparative Biology. 55, 2015, pp. 718-727. (academic.oup.com)
- ↑ youtube.com