Short-snouted marlin
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Short-snouted marlin ( Tetrapturus angustirostris ) |
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| Tetrapturus angustirostris | ||||||||||||
| Tanaka , 1915 |
The short-snouted marlin ( Tetrapturus angustirostris ) is a large predatory fish that is found in the tropical and subtropical Pacific and Indian Oceans . It avoids coasts, its distribution area extends in the Pacific from 40 ° north to 35 ° south latitude , in the Indian Ocean it is between 20 ° north and 45 ° south latitude.
features
The short-snouted marlin becomes a maximum of 2.30 meters long, but usually stays just under two meters. The average length between the eye and the tail of the specimens caught in the central South Pacific is 1.35 meters, while catches from the Eastern Pacific are 1.50 meters. The maximum published weight is 52 kg, the average weight is 18 kg. The body is elongated, laterally flattened and is densely covered with elongated scales, each of which ends in three to five points at its rear edge. The single sideline is clearly visible. The number of vertebrae is 24, 12 trunk and 12 tail vertebrae. The gonads are Y-shaped.
The fish are dark blue on the back, brownish to bluish on the sides and silvery white on the belly. There are no stains or other patterns on the pages. The first dorsal fin is black-blue without pattern, the remaining fins are brown or brown-black, and the bases of the anal fins are often silvery white. The first dorsal fin is supported by 45 to 50 fin rays, the second by 6 to 7. The first dorsal fin has a high point at the front that is higher than the body height of the fish. It then drops off steeply and remains at the same height until the 19th fin ray and then drops again.
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Of the two anal fins, the first has 12 to 15, the second 6 to 8 fin rays. The second dorsal and anal fins are symmetrically opposite each other and are very similar in shape and size. The pectoral fins are supported by 17 to 19 rays. The pelvic fins are narrow, twice as long as the pectoral fins and reach 15% of the body length. The tail fin stalk is strongly flattened on the sides and provided with a double keel and a shallow notch on the back and the belly side on each side. The anus sits in front of the beginning of the first anal fin at a distance that is usually longer than the height of the first anal fin.
Similar to the closely related Mediterranean spearfish , its spear-like elongated, round cross-section, rostrum is significantly shorter than other spearfish and only reaches 15% of the body length. The elongated lower jaw reaches more than ² / ³ of the upper jaw rust. Both jaws and the palatine bone are covered with fine teeth, gill traps are missing, the right and left Branchiostegal membranes have grown together but are free from the isthmus .
Way of life
The short-nosed marlin is an oceanic, pelagic fish that does not normally approach the coast. The Indo-Pacific species, which undertake long migrations, have only occasional sightings and catches from the South Atlantic. It is assumed that the spawning grounds are in the Indo-Pacific. When fishing for longlines in the equatorial Indian Ocean, the fewest specimens were caught in the upper water layers (0 to 200 meters), most of them at depths of 915 to 1830 meters.
Like all spearfish , Tetrapturus angustirostris is a predatory fish that feeds on fish, cephalopods and crustaceans. The prey fish include mackerel , mackerel , flying fish , sea bream , medusa and lance fish , bonitos . Deep sea fish such as lantern fish and deep sea hatchet fish are absent. It also doesn't eat as large prey fish as other spearfish.
The fish spawn in the western Indian Ocean during the winter months and in the central Pacific in March. The pelagic spawn and fish larvae also occur mainly in winter. The eggs have a diameter of 1.0 to 1.6 mm, they are colorless, semi-transparent and contain a yellowish-brown drop of fat.
use
The short-snouted marlin is not specifically pursued. It is rarely caught as bycatch when fishing for fanfish or tuna with longlines or by deep-sea anglers. Its meat is not of the high quality of other spearfish, but it is mainly marketed fresh or frozen in Japan, prepared as sashimi or used to make fish sauce.
literature
- William N. Eschmeyer, Earl S. Herald, Howard Hammann, Katherine P Smith: Pacific Coast Fishes. Peterson Field Guides, Boston 1983, ISBN 0-395-33188-9 .
- 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 . (on-line)
Web links
- Short-snouted marlin on Fishbase.org (English)
- Tetrapturus angustirostris inthe IUCN Red List of Threatened Species 2013.2. Posted by: Collette, B., Acero, A., Canales Ramirez, C., Carpenter, KE, Di Natale, A., Fox, W., Miyabe, N., Montano Cruz, R., Nelson, R., Schaefer, K., Serra, R., Sun, C., Uozumi, Y. & Yanez, E., 2009. Retrieved February 4, 2014.