Large scale gurnard
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Large scale gurnard ( Lepidotrigla cavillone ) |
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| ( Lacepede , 1801) |
The large-scale gurnard ( Lepidotrigla cavillone) is a small and ground-living species of the gurnard family (Triglidae). It is the most common species of eight species of gurnard in the Mediterranean . It can also be found on the eastern Atlantic and on the south coast from Portugal to Mauritania. Depending on age and sexual maturity, it stays at a depth of between 30 and 450 meters, where it rummages through the seabed with its long snout in search of food.
Systematics and synonyms
Lacepède (Bernard-Germain-Étienne de La Ville-sur-Illon) named and described the species Lepidotrigla cavillone as early as 1801. Lacepède used Trigla cavillone as a synonym . The zoologist Georges Cuvier established the synonyms Trigla aspera and Lepidotrigla aspera for the same species in 1829 . Today the species name 'Großschuppiger-Knurrhahn' is used in German and 'Large-Scaled Gurnard' in English. Subspecies are not known.
features
The large-scale gurnard has two dorsal fins, a caudal fin, an anal fin, throaty pelvic fins and pectoral fins with three individual hard rays, as these are characteristic of gurnards . The individual rays are not only used for locomotion, but mainly as a tactile organ. The longest of these rays is relatively short in the large scale gurnard. It doesn't reach the anus. The first and higher of the two dorsal fins has 8–10 rays. The second dorsal fin and the anal fin 14–16 soft rays.
The large scale gurnard has an elongated body with a relatively large head, steep in profile, which is equipped with numerous bony ridges and spines. There is a notch on the back of its head, which clearly distinguishes it from other species of gurnard. There is a spine in front of the eye, as well as on the shoulder girdle and on the gill cover. The rostrum (pre-orbital bone) is short and slightly indented. In contrast to other species of gurnard, such as B. the red gurnard, the large scale gurnard has no teeth in the palate.
The large scale gurnard has ctenoid scales (a maximum of 70 in a central longitudinal row), which are higher than long and firmly attached to the body - with the exception of the breast, which is scaly. The spine consists of 30 to 32 vertebrae. The color of the body is pink to dusky pink. The pectoral fins are dark blue with pink at the base. It reaches an average body length of approx. 12 cm. The maximum length can be up to 20 cm.
distribution
The large-scale gurnard is common in the east Atlantic, on the south coast of Portugal as far as Mauritania (south of Morocco) and in the Mediterranean. He cannot be found in the Black Sea.
Way of life
The large-scale gurnard is a marine, bottom-living fish that feeds on crustaceans on sand and gravel at a depth of 30–450 m. The most commonly consumed prey (up to 80%) are Mysidaceae , so-called glass crabs and amphipods , colloquially called amphipods . The dominant species of the Mysidaceae is the Lophogaster typicus (up to 70% of the consumed Mysidaceae), which is mainly found during the day. In the spring, small amounts of Euphasiaceae ( luminous shrimp ) are also part of the diet of the large scale gurnard. In comparison to other gurnard species, which z. B. also consume larger amounts of fish and decapoda , a very specialized diet. The composition and amount of food varies depending on the subsoil, sediment, depth and season. In summer, for example, the large scale gurnard consumes on average twice as much as in winter, including larger amounts of amphipods . To catch the prey itself, it digs into the ground with its long, shovel-shaped snout.
Most often it is found at a depth of 60-200 meters. After spawning at a depth of approx. 60 meters, young animals (<7 cm) stay near the coast in shallow waters (30 meters deep) until the end of their first year of life. They then retreat to deeper waters (60–100 meters) away from the coast.
The name of the family, and thus also of the large scale gurnard, is the ability to make growling or grunting noises. These are produced by a muscle that makes the swim bladder vibrate. This type of noise is triggered especially during the mating season, but also by disruptive factors. In the attitude of gurnards, the "growling" was also observed when feeding. The frequency is between 40 Hz and 4 kHz.
Reproduction
The large scale gurnard spawns mainly between May and July at a depth of about 60 meters. A female can lay 500 to several thousand eggs, which are between 0.2 and 1 mm in size. The larvae develop pelagially. At 1.5–2 years of age, it reaches sexual maturity with a length of approx. 10 cm +/- and more than half of its maximum size. A reduction in the growth rate can then be observed. Females of the large-scale gurnard, which can reach sexual maturity with a length of approx. 7 cm, stay at this stage of life mainly at depths of 80-100 meters. The minimum depth at which spawning occurs is 60 meters. In this way, a relationship between sexual maturity, size and depth of the habitat can be established.
Importance to humans
The large scale gurnard is harmless to humans.
In a commercial sense, it is used rather little. However, it can be found regularly in the markets of the western Mediterranean and Cyprus. In Turkey it again has a low commercial value. It has become bycatch in many places through trawls.
Apart from the distribution and commercial use, little is known about the exhaustion of the stocks. It has not yet been evaluated in the Red List. In general, the species can be protected by maintaining the minimum size of the mesh of the net of 40 mm. Often this is only 22–24 mm, so that juvenile fish get caught in the fishing nets before they reach sexual maturity and are able to reproduce. The death rate from fishing is often underestimated
supporting documents
- ↑ a b c Ilkyaz, AT & Metin, G. & Soyakan, O. et al. (2010): Growth and Reproduction of Large-Scaled Gurnard ( Lepidotrigla cavillone Lacepede, 1801) (Triglidae) in the Central Aegean Sea, Eastern Mediterranean. Tübitak, 34: pp. 471-478.
- ↑ a b c d e f g h Froese, R. & Pauly, D. (2018): Eds. Fishbase. www.fishbase.org. (last accessed December 18, 2018)
- ↑ a b c d e Colloca, F. & Cardinale, M. & Ardizzone, GD (1997): Biology, Spatial Distribution and Population Dynamics of Lepidotrigla cavillone (Pisces: Triglidae) in the Central Thrrhenian Sea. Fisheries Research, 32: pp. 21-32.
- ↑ a b c Arias, AM & de la Torre, MI (2013): Edt. Base de Datos Terminilogicos y de Identification de Especies Pesqueras de Las Costas de Andalucia. [1] (last accessed December 19, 2018).
- ↑ a b c Hureau JC (1986): Triglidae. In: Fishes of the north-eastern Atlantic and the Mediterranean. (Whitehead PJP, Bauchot M.-L., Hureau J.-C., Nielsen J. & E. Tortonese, eds.), 3: pp. 1015-1473. UNESCO.
- ↑ a b Terrats, A. & Petrakis, G. & Papaconstantinou, C. (2000): Feeding Habits of Aspitrigla cuculus (L., 1758) (Red Gurnard), Lepidotrigla cavillone (Lac., 1802) (Large Scale Gurnard) and Trigloporus lastoviza (Brunn., 1768) (Rockgurnard) around Cyclades and Dodecanese Islands (E. Mediterranean). Mediterranean Marine Science, 1 (1): pp. 91-104.
- ↑ Caragitsou, E. & Papaconstantinou, C. (1990): Food and Feeding Habits of Large Scale Gurnard, Lepidotrigla cavillone (Triglidae) in Greek Seas. Internationa Journal of Ichthyology, 14 (2): pp. 95-104.
- ↑ Amorim, MCP (2006): Diversity of Sound Production in Fish. [2] (last accessed December 19, 2018).
- ^ Fischer, W. & Schneider, M. & Bauchot, ML (1987): Méditerranée et Mer Noire - Zone de Pêche 37. In: Guide FAO d'Identification des Espèces pour les Besoins de la Pêche, Vol. 2: Vertébrés. Rome.
- Jump up ↑ Ragonese, S. & Bianchini, ML (2010): Historical Growth and Mortality 'Benchmark' Values of Lepidotriga cavillone (Pisces-Triglidae) in the Strait of Sicily (Mediterranean Sea). Journal of Applied Ichthyology, 26: pp. 113-115.
Web links
- Large Scale Gurnard on Fishbase.org (English)