Mediterranean horse mackerel

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Mediterranean horse mackerel
Trachurus mediterraneus Taxonbox.jpg

Mediterranean horse mackerel ( Trachurus mediterraneus )

Systematics
Carangaria
Order : Carangiformes
Subordination : Mackerel relatives (Carangoidei)
Family : Jackfish (Carangidae)
Genre : Trachurus
Type : Mediterranean horse mackerel
Scientific name
Trachurus mediterraneus
( Steindachner , 1868)

The Mediterranean horse mackerel ( Trachurus mediterraneus ), also called Mediterranean horse mackerel or Mediterranean horse mackerel , is a species of fish from the family of jacks (Carangidae). It is a benthopelagic marine fish, which means that it prefers to live in open water just above the seabed.

features

Mediterranean horse mackerel have a hydrodynamic, elongated, spindle-shaped and smooth-looking body that is more pointed than that of the common horse mackerel ( Trachurus trachurus , ) which is significantly higher and flattened. The largest specimens are up to 60 cm long, with the majority of the animals between 30 and 50 cm in size. The paired pectoral fins are longer than the head and the caudal fin is forked, it has a yellowish color. The back (including the head) is yellowish-brown to blue-green and dark-gray in color, while the underside is significantly lighter, namely whitish to silvery. The rear end of the upper jaw extends almost to the edge of the eye, where a fatty eyelid is developed. T. mediterraneus has two pairs of nostrils, the front being more rounded and the rear half-moon shaped.

Mediterranean horse mackerel

Like its entire family, the Mediterranean horse mackerel has two dorsal fins, with the first dorsal fin having eight hard rays. Characteristic is a dark, vertically elongated spot at the top of the posterior edge of the gill cover, which is often invisible in situ (= natural position of the body). There is also a clear indentation at the rear edge of the operculum . In addition, the species has a curved side line that is arched dorsally over the pectoral fin . Especially with some types of trachurus there is an additional side line along the back profile, which is called the accessory side line. This extends approximately to the junction of the two dorsal fins. In the very similar species T. trachurus, this second lateral line extends almost behind the second dorsal fin. On the curved (normal) side line one can see large, thick bone scales, also called shields, which are a typical feature of the genus Trachurus . The shields are less high in the front than in the back and overall much smaller in T. mediterraneus than in T. trachurus.

Geographical occurrence

Trachurus mediterraneus is a saltwater fish that occurs in the eastern Atlantic and the Mediterranean including the Black Sea , which corresponds to the coordinates 49 ° N - 28 ° N, 13 ° W - 43 ° E. According to the FAO [= Food and Agriculture Organization of the United Nations], the Mediterranean horse mackerel can be found in the three areas of the Northeast Atlantic (number 27), the Middle East Atlantic (number 34) and the Mediterranean with the Black Sea (number 37). The species is found in the East Atlantic between the Bay of Biscay and Mauritania . In the Mediterranean itself, of course, the species occurs more or less frequently in all parts. The subspecies Trachurus mediterraneus ponticus (Aleev 1956) occurs only in the Marmara Sea , in the Black Sea and in the southern and western parts of the Azov Sea .

Distribution area

Population structures

The population size and structure of individual populations of species of the genus Trachurus are not easy to estimate, which makes precise statements difficult. In 2004, however, an attempt was made to investigate the population structure of T. picturatus , T. mediterraneus and T. trachurus using regions of mitochondrial DNA . No evidence of a separation between Atlantic populations and populations of the Mediterranean could be found, which is probably due to the ability of Trachurus species to migrate long distances. More recent findings even assume good networking between the Mediterranean and the Atlantic.

Within the Mediterranean, based on countable characteristics such as: B. fins and scales, and morphometric analyzes, which relate to form and shape, make statements about the population structures. You notice a certain connectivity (connectedness) of the individual stocks. Investigations of the mitochondrial 16s rDNA provide genetic evidence for a significant heterogeneity between individual T. mediterraneus stocks in the Aegean , Ionian and western Mediterranean. It can currently be assumed that individual populations are not seriously isolated.

Lifestyle and diet

The Mediterranean horse mackerel prefers to stay at depths between 10 and 50 meters close to the bottom (benthopelagic way of life). But it can also be found at depths between 5 and 400 meters. Overall, T. mediterraneus has a temperature optimum between 14 and 20 ° C water temperature and a life expectancy of around 15 years, although the age is difficult to estimate. A study also found that the females are on average significantly larger and heavier than the males.

The species occurs in large swarms mostly over silt and sandy bottoms. T. mediterraneus forms large schools for migration , often together with other Trachurus species ( T. trachurus, T. picturatus ), and lives in open water ( pelagic ).

T. mediterraneus is a predatory shoal fish which has a wide food spectrum: smaller fish such as sardine or anchovy fish fry and fish eggs and small crustaceans (= Crustacea ), such as copepods ( Copepoda ), flea crabs ( Amphipoda ), water-fleas (Cladocera), krill (Euphausiacea), Schwebgarnelen ( Mysid ) and shrimps ( decapods = decapods). Especially small and medium-sized individuals of the mackerel species prefer to feed on hover shrimp.

T. mediterraneus is a predatory species, but is also hunted by some other species themselves, such as the pelamids ( Sarda sarda ). In addition, Lernanthropus trachuri (Brian, 1903) is added to the species of the ectoparasitic copepod .

Reproduction

Mediterranean horse mackerel reach sexual maturity at two to three years of age, reaching a size of around 16 cm. Spawning takes place annually between May and August, with the females spawning about once a week during this period. The resulting pelagic eggs have a diameter of about 1 mm and are located near the surface. In spring, populations are characterized by a high average weight and size. These parameters decrease in autumn, as the young are even smaller and lighter. During the youth stage, the juveniles gather under the shelter of jellyfish, e.g. B. the fried egg jellyfish ( Cotylorhiza tuberculata ). With a size of about five centimeters they leave the jellyfish and move as a swarm through the open water, where they often mix with yellow welts ( boops boops ) and sardines at first .

Young fish with fried egg jellyfish

Hike

Trachurus mediterraneus undertakes seasonal migrations in large schools, staying near the surface. For example, no adult individuals (> 12.5 cm) are found on the Golden Horn in the mouth of the river in Istanbul during the summer, while the juveniles are there between May and August. Also in the north-western Mediterranean, the Lingurian Sea , juveniles of T. mediterraneus occur in the shallow water in summer .

Use and importance for humans

The Mediterranean horse mackerel is a very commercially important fish and one of the main economic resources of the Mediterranean. It is a popular food fish, especially in the eastern Mediterranean and the Black Sea, but it is not eaten as often in the Atlantic. That is why over 90% of the reported catches are made in the Eastern Mediterranean and Black Seas. Of the important Trachurus species, T. mediterraneus is more common than T. picturatus , but less common than T. trachurus . For this reason, the price of Mediterranean horse mackerel in the eastern Mediterranean is three to four times higher than that of T. trachurus . Overall, the catches are often mixed from the different species, all of which are used (e.g. as fresh fish, canned fish or as fish meal). In the Black Sea, 54% of the fishery yields are from Trachurus spec. to the subspecies T. mediterraneus ponticus . The stocks have been overfished here several times in the past, leading to a population collapse in the 1960s and 1980s. According to the FAO, catches in the Black Sea have fallen dramatically since a peak in 1986 from 122,827 t to 18,000 t in 1997 and around 9,146 t in 2002. Between 2004 and 2016, the yields stabilized at around 25,000 tons per year. Most of the fishing is done in Turkey (9220 tons), closely followed by Greece (3534 tons). The catch of T. mediterraneus accounts for 6.5% of the total fishery yield in Greece. It has been observed that captured individuals have clearly lost size between 1994 and 2002. Commercial use is made of pelagic nets and bottom trawls , longline fishing , purse seine nets (with lights), traps and angling with bait.

Trapped tons of T. mediterraneus.png

threat

According to the red list of endangered species of the IUCN [= International Union for Conservation of Nature and Natural Resources (German = "International Union for the preservation of nature and natural resources")] the Mediterranean horse mackerel is "least concern". This means that it is currently not endangered and its assessment does not fall into the categories of "critically endangered, critically endangered, endangered or potentially endangered". Only species that are widespread and common are given the status of “least concern”.

In addition, the species seems to be resilient, as it has been able to recover from several stock collapses due to overfishing in the past . Furthermore, there are marine protected areas in their area of ​​distribution, in which they can also relax.

Nomenclature and Taxonomy

The term 'trachurus' comes from the Greek and means something like 'rough tail' (trachys = rough, oura = tail) and the species name 'mediterraneus' alludes to its main distribution in the Mediterranean. T. mediterraneus was first described by the Austrian zoologist Franz Steindachner in 1868 . There are typical national names for this species in practically all countries bordering the Mediterranean or the Atlantic. These are z. B. Mediterranean Horse Mackerel (English), Chicharro (Spanish), Tracuro (Italian), Sari (Turkish), Sarun (Croatian), Chinchard de la Mediterranée (French), whereby there are also some subject-specific synonyms: Caranx trachurus mediterraneus Steindachner 1868, Trachurus mediterraneus mediterraneus (Steindachner 1868), Suareus furnestini (Dardignac and Vincent 1958). The subspecies Trachurus mediterraneus ponticus (Aleev 1956) also occurs in the Black Sea .

literature

  1. ^ A b c Louisy, P .: Marine fish Western Europe Mediterranean, 750 species - 800 color photos - 1000 drawings and maps . Verlag Eugen Ulmer, Stuttgart 2002, p. 57 f .
  2. ^ A b c d Neumann, V., Paulus, T .: Mediterranean Atlas: Fish and their habitats . Mergus Verlag GmbH for nature and pet science, Melle 2005, p. 1119 f., 1136 f .
  3. ↑ a b c d e FAO Fisheries & Aquaculture - Aquatic species. Retrieved March 2, 2017 (English).
  4. ↑ a b c d e f g h https://apiv3.iucnredlist.org/api/v3/taxonredirect/198645
  5. ↑ FAO Areas Species - Trachurus mediterraneus. Retrieved March 2, 2017 (English).
  6. ↑ Fish stocks online. Barz K., Zimmermann C., accessed on November 22, 2016 .
  7. ^ Sahin, C. et al .: Age, Growth, and Gonadosomatic Index (GSI) of Mediterranean Horse Mackerel (Trachurus mediterraneus Steindachner, 1868) in Eastern Black Sea . In: Turkish Journal of Zoology . tape 33 , 2009, p. 157-167 .
  8. ^ Predators - Trachurus. Retrieved March 2, 2017 (English).
  9. ^ WoRMS - World Register of Marine Species - Trachurus mediterraneus (Steindachner, 1868). Retrieved March 2, 2017 .
  10. ↑ Sahin, C., Hacimurtazaoglu, N .: Abundance and distribution of eggs and larvae of anchovy (Engraulis encrasicolus, Linnaeus, 1758) and horse mackerel (Trachurus mediterraneus, Steindachner, 1868) on the coasts of the eastern Black Sea . In: Turkish Journal of Zoology . No. 37 , 2013, p. 773-781 .
  11. ↑ Demirel, N., Yüksek, A .: Spawning Frequency of Trachurus mediterraneus (Carangidae) in the Sea of ​​Marmara . In: Turkish Journal of Fisheries and Aquatic Sciences . No. 13 , 2013, p. 441-446 .
  12. ↑ Tzikas, Z. et al .: Seasonal size distribution, condition status and muscle yield of Mediterranean horse mackerel Trachurus mediterraneus from the North Aegean Sea, Greece . In: Fischeries Science . No. 73 , 2007, pp. 453-462 .
  13. ↑ a b Patzner R., Moosleitner H .: Underwater Guide Mediterranean: Fish . 3. Edition. Verlag Stephanie Naglschmid, Stuttgart 2006, p. 58 .
  14. ↑ Karlou-Riga, C .: Otolith morphology and age and growth of Trachurus mediterraneus (Steindachner) in the Eastern Mediterranean . In: Fisheries research . No. 46 , 2000, pp. 69-82 .
  15. ↑ Tsikliras, AC, Stergiou, KI: Age at maturity of Mediterranean marine fishes . In: Mediterranean Marine Science . No. 16 , 2014, p. 5-20 .
  16. ↑ Demirel, N., Yüksek, A .: Seasonal distribution of Trachurus mediterraneus (Steindachner, 1868) in the Golden Horn Estuary, Istanbul . In: Turkish Journal of Zoology . No. 38 , 2014, p. 361-368 .
  17. ↑ Turan, C .: Stock identification of Mediterranean horse mackerel (Trachurus mediterraneus) using morphometric and meristic characters . In: Ices Journal of Marine Science . No. 61 , 2004, p. 774-781 .
  18. ↑ Categories and Criteria (version 3.1). Retrieved March 2, 2017 .
  19. ↑ Trachurus mediterraneus summary page. Retrieved March 2, 2017 (English).
  20. ↑ Common Names List - Trachurus mediterraneus. Retrieved March 2, 2017 (English).
  21. ↑ Synonyms of Trachurus mediterraneus (Steindachner, 1868). Retrieved March 2, 2017 .

Web links

Commons : Mediterranean horse mackerel ( Trachurus mediterraneus )  - Collection of images, videos and audio files