White marlin
| White marlin | ||||||||||||
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White marlin ( Kajikia albida ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Kajikia albida | ||||||||||||
| ( Poey , 1860) |
The white marlin ( Kajikia albida ) is a large oceanic predatory fish found in the Atlantic , while its sister species , the striped marlin ( Kajikia audax ), inhabits the Indo-Pacific .
features
The white marlin becomes approx. 3 m long and weighs over 80 kg. The skin is covered with very small, pointed scales (also on the rostrum or " beak "), so it is somewhat similar to that of sharks. The color of the back is a deep dark blue, usually with 16 to 22 narrow, light saddle pads; the sides are silver-white, but often cloudy brown. The elongated dorsal fin is highest in the front section, then slowly falls off and forms a broad, flipper-like section on the tail; both sections are dark blue, the front area is dotted black in front. The pectoral and anal fin are dark blue (almost black), the latter is divided into two parts. The pectoral fin, which has a rounded tip, often shows bright spots. The pelvic fins are stiff whips the length of the pectoral fin. The caudal fin is rather dark brown and surprisingly narrow (if you consider that it is the main propulsion mechanism). It is stiff and high, almost sickle-shaped. In juvenile fish of about 12 cm in length, the dorsal fin is still sail-shaped and has some eye spots.
Fin formula : D 43–52 (hardblasting), A 17–23, P 18–21, VI / 2, C 18–19. The fish has (2n =) 48 chromosomes, 24 vertebrae and no gill trap .
distribution
The northern limit of distribution runs roughly between Cape Hatteras and the Biscay , the southern between the Mar del Plata (but the fish avoids sweetness zones) and the Cape region of South Africa. This marlin is already very rare in the English Channel, especially in winter and spring, especially as it avoids shallower waters (<100 m) and water temperatures below 22 ° C.
The white marlin lives in the subtropical to tropical parts of the Atlantic, rarely also in the western half of the Mediterranean (see also the Mediterranean marlin ). Although the Tetrapturus species are less tied to the continental shelf than the Istiophorus species and are even more sedentary, they are seldom found in the offshore high seas. It is therefore unclear whether there are two distinct populations (one north and one south Atlantic) according to the superficial ocean current systems.
Stronger ocean currents don't bother him. He especially likes to find himself at water mass boundaries, upwelling zones, break edges and over submarine gorges.
nutrition
Schooling fish (such as herring , flying fish , mackerel , sunfish , perch ), squids and even smaller sharks are the main food of the marlin. He hunts them individually or in loose groups. By hitting with the rostrum it makes its prey incapable of escape.
Multiplication
The white marlin reaches sexual maturity from a size of approx. 1.3 m, whereby the females are always larger than the males. The white marlin spawns far from the coast, at 24–29 ° C, in open water (Nakamura 1985).
threat
The white marlin is a sought-after edible as well as a famous sport fish, which attracts attention with its huge leaps in the air when deep-sea angling. Despite the conservation policies that should help preserve the species, the white marlin is on the verge of extinction.
While the greatest danger comes from industrial longline fishing , the danger from trolling plays only a negligible role. It turned out, however, that white marlins are only caught with long lines in their natural habitat, between 25 m and 175 m depth. Targeted protection is therefore possible, because other sought-after fish go deeper.
The threats to the marlin also include fast sharks such as the great white shark ( Carcharodon carcharias ), mako sharks ( Isurus ) and the small cigar sharks ( Isistius ), which sometimes cut holes in its skin. There are also the usual ecto- and endoparasites, against which neither fast swimming nor jumping in the air help.
literature
- I. Nakamura (1985): FAO species catalog. Vol. 5. Billfishes of the world. An annotated and illustrated catalog of marlins, sailfishes, spearfishes and swordfishes known to date. FAO Fish. Synopsis 125 (5). 65 p.
Web links
- White Marlin on Fishbase.org (English)
- Kajikia albida onthe IUCN Red List of Threatened Species .
supporting documents
- ↑ For biology see especially http://www.flmnh.ufl.edu/fish/gallery/descript/whitemarlin/whitemarlin.html
- ↑ http://www.bigmarinefish.com/white_marlin_ESA_listing_petition_pg1.html
- ^ Report of the 2006 ICCAT Billfish Stock Assessment ( Memento of July 3, 2007 in the Internet Archive )