Zoarces americanus
| Zoarces americanus | ||||||||||||
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Zoarces americanus |
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| Scientific name | ||||||||||||
| Zoarces americanus | ||||||||||||
| ( Bloch & Schneider , 1801) |
Zoarces americanus ( Syn . : Macrozoarces americanus ) is afish that is nativeto the coast of northeastern North America, its English name Ocean pout could betranslatedas sea stubborn . It isvery similar tothe European eel mother ( Zoarces viviparus ), but unlike her, it is not viviparous .
Special features
The length of the fish is eight to eleven times (young fish) its height. Compared to the eel mother, the jugular (ie standing at the "throat") pelvic fins are very small and short. The dorsal fin is connected to the caudal fin by the prickly section and is higher than that of the eel mother. The edge of the unpaired fins is supported by approx. 260 mostly flexible rays (D: 95-100 + 16-25 St. + C: approx. 25 + A: 100-118). The sting part is perhaps important during the egg-laying, the act of spawning . The number of vertebrae is 131-144 and thus differs from that of the eel mother. The scales are very small and thickly covered with mucus. It is believed that when threatened, like the hagfish , the fish produces additional mucus.
The rather large mouth is underneath, with thick, soft "lips". The teeth form two rows one behind the other, the second row is replacement teeth that can move outwards if necessary.
Zoarces americanus can move in different ways, rowing with the pectoral fins (labriform), by undulating movements of the unpaired fin like with the puffer fish ( tetraodontiform ) or like with the eel-like ( anguilliform ) with the tail (also backwards).
The color is very variable, from orange or brownish yellow-gray to dark olive-green, with all sorts of darker, cloudy spots, e.g. Sometimes in rows on the dorsal and anal fin. A dark streak always runs through the small eye to the gill cover. Young fish have a black spot in the front of the dorsal fin.
Zoarces americanus can be twice as long as the eel mother (over 1 m) and weighs over 6 kg, but most catches are significantly smaller (30–70 cm). The age can be up to 18 years.
food
Mollusks like mussels and snails are eaten with their shells; next feeds Zoarces americanus of echinoderms , crustaceans , worms, and tunicates , fish he caught mostly only as carrion. The fish eats between 0 and 17 ° C. Initially, the young mainly live on copepods ( Harpacticoida ). According to MacDonald (1983), the fish also takes its mouth full of sediment and sorts out food.
Reproduction
Towards the end of the 1930s, a rubber boot was fished from the Passamaquoddy Bay in which a pair of Zoarces americanus guarded a pile of yellowish jelly-like eggs from which some 3 cm long fry had already hatched. Since then it has been clear that the Dickkopf does its spawning business in a similar way to the butterfish ( Pholis ). The eggs are fertilized by the male with his genital papilla still in the fallopian tube of the female, at temperatures below 10 ° C. The number of eggs can exceed 4000, but the females that spawn at three to four years of age are only about 30 cm long and have around 1000 eggs. The spawning season is autumn, the young appear 2-3 months later (December – February).
Occurrence
Labrador to Virginia (in the southern parts of the Labrador Current ; therefore with "frost protection" - glycoproteins ). Near the coast, the fish can be found in shallow water or in the intertidal zone (especially the juvenile fish), further seaward it lives in greater depths of up to about 400 m on sandy, gravel and rocky bottoms, but also occurs in the seagrass and seaweed Vegetation in front. He is quite faithful to the location and at most makes shorter hikes in season. It sometimes penetrates estuaries but avoids fresh water.
fishing
Zoarces americanus is considered an edible fish, but until the 1930s it was mostly discarded as unused bycatch in commercial fisheries . During the Second World War , a commercially quite successful fishery for Zoarces americanus developed for a short time in 1942-45 , which, however, came to an end again soon afterwards when unicellular parasites were discovered in the meat, which caused the demand to collapse.
In the late 60s and early 70s, the ocean pout was heavily fished industrially for use as fish meal , after which it only played a minor role as a locally marketed fish fillet in the late 90s. Since that time the catch has decreased continuously and are now of no economic importance. The strong fluctuations in the catches can v. a. can be attributed to changes in the legal regulations, for example to the permissible mesh sizes of the trawls used.
relationship
Zoarces viviparus and Z. americanus are to be understood as vicarious species that were divorced (perhaps 3 million years ago) by the continental drift . In North America, the species is often viewed as a representative of its own ( monotypical ) genus, Macrozoarces Gill 1863: Fishbase and JS Nelson (2006) can - also with good reasons - but not "get through": the question is objectively undecidable.
literature
- Henry B. Bigelow & William C. Schroeder (1953): Fishes of the Gulf of Maine. Fishery Bulletin of the Fishery and Wildlife Service 53: 510-515. Available online: Ocean Pout (accessed March 13, 2011)
Notes and web links
- Zoarces americanus on Fishbase.org (English)
- ↑ on biology see: W. Frank Steimle, Wallace W. Morse, Peter L. Berrien, et al .: Ocean Pout, Macrozoarces americanus, Life History and Habitat Characteristics . Northeast Fisheries Science Center, NOAA Technical Memorandum NMFS-NE-129, September 1999 (accessed March 13, 2011; PDF; 2.5 MB)
- ↑ cf. Biegelow and Schröder (1953), note 49: cf. White, Jour. Fish. Res. Vol. Canada, vol. 4, pt. 5, 1939, pp. 337-338.
- ↑ Zuxu Yao and Laurence W. Crim: Spawning of ocean pout ( Macrozoarces americanus L.): evidence in favor of internal fertilization of eggs. In: Aquaculture vol. 130: 4, 1 March 1995, pages 361-372 ( doi : 10.1016 / 0044-8486 (94) 00337-N )
- ^ Biegelow and Schröder (1953), Section Importance .
- ^ SE Wigley, L. Col, and CM Legault: Section O: Ocean pout . In: Northeast Fisheries Science Center. 2008. Assessment of 19 Northeast Groundfish Stocks through 2007: Report of the 3rd Groundfish Assessment Review Meeting (GARM III) , Northeast Fisheries Science Center, Woods Hole, Massachusetts, August 4–8, 2008. Available online: Section O: Ocean pout ( Memento from August 19, 2014 in the Internet Archive ) (English; PDF, 299 kB); see. also Steimle et al. (1999), p. 5: Status of the Stocks.