Hyperprosopon argenteum

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Hyperprosopon argenteum
Hyperprosopon argenteum - from Brehms Thierleben, 3rd edition, vol. 8, 1892

Hyperprosopon argenteum - from Brehms Thierleben , 3rd edition, vol. 8, 1892

Systematics
Perch relatives (Percomorphaceae)
Ovalentaria
incertae sedis
Family : Surf perch (Embiotocidae)
Genre : Hyperprosopon
Type : Hyperprosopon argenteum
Scientific name
Hyperprosopon argenteum
Gibbons , 1854

Hyperprosopon argenteum (English Walleye Surfperch ) is a schooling sea ​​fish from the surf perch family. He lives on the Pacific coast of North America .

features

Like all surf perch, Hyperprosopon argenteum is oval, disc-shaped, i.e. high-backed and rather flattened on the sides. It becomes a maximum of 30 cm long. This shape is characteristic of fish that live in the surf zone, but go to places with little current to acquire food. The spine (33–37 vertebrae) runs straight through the body.

The color is (bluish) silvery with a slightly darker head and back. The fish often show up to twelve dark bands across the sides, which appear slightly offset from one another above and below the curved side line . Sometimes you can also see about 20 horizontal, shimmering stripes over the sides of the fuselage. The scales are very small (approx. 80 along the sideline) and smooth-edged ( cycloid ).

Fins

Fin formula : D VIII – X / 25–28, A III / 33–35, P 25–28, VI / 5, C 21.

The pectoral fin is remarkably rich in radiation. The middle dorsal hard rays are the longest. As with all surf perch, the dorsal fin is laid down in a wide furrow (hence an earlier name for the family "Holconoti", " furrow back ").

The pelvic fins are almost bulbous and lined with black towards the outer edge. This feature makes it easy to distinguish Hyperprosopon argenteum from similar species such as Hyperprosopon ellipticum .

The swimming style of Hyperprosopon argenteum is - also characteristic of the family - labriform . The fish holds its trunk and tail steady and rows its large triangular pectoral fins. In pictures these are often shown strongly folded. But when they are spread out against the trunk, their trailing edge is half as high as this. The caudal fin is only used for acceleration in an emergency, for example to escape or in a strong current - otherwise only as a control.

skull

The head is completely scaled. The mouth is finely toothed, and there are often replacement teeth behind the front row of teeth. The ploughshare (vomer) and the adjoining palatine bones (palatina) are, as is generally the case with the subordination of the wrasse-like, toothless. The upper jaw can hardly be advanced.

The size of the eyes (3/8 to 1/3 the length of the head) is very striking. All surf perch are big-eyed, but this is especially true for hyperprosopon , although surf perch are mostly diurnal. However, the fry (0+) seem to eat plankton at night too. The larger fish spend the night in the seaweed forest off the coast. The reason for the common English name Walleye Surfperch is a light reflection on a retina - tapetum , which improves twilight vision, similar to that of the cat. The absorption maximum of the visual pigments is shifted towards yellow, as is the case with other fish in this hardly ever clear sea zone.

The prefrontal is widened in the middle and supports the eyeball in front. The surf perch have five or six branchiostegal rays and no pyloric tubes .

Occurrence and ecology

Hyperprosopon argenteum occurs between the south coast of Vancouver Island in British Columbia ( Canada ) and Punta Rosarito on the coast of the state of Baja California ( Mexico ) as well as around Isla Guadalupe . It is common near the coast where there is a sandy bottom between rocks with algae growth (e.g. seaweed), including at harbor moles and jetties .

The temperature range of this species, which occurs from subtropical to temperate latitudes, is between 7 and 21 ° C. There are corresponding seasonal hikes in deeper (up to about 30 m) or shallower water. Some of the fish migrate to shallower bays such as Humboldt Bay in California to spawn in summer . Occasionally, individual schools penetrate into the estuaries of rivers, but the brackish water does not disturb them. Their diet consists of smaller epibenthic crustaceans ( amphipods , sea ​​lice , small decapods , hover shrimp , mussel shells ), as well as bristle worms , fish eggs and larvae. Accordingly, the gill trap is well developed (with about 32 spines on the first gill arch). In contrast to those of several other bearfish species, their pharyngealia (the ventral ones are fused) are too weak to be able to crush snails or mussels in significant quantities. The fish have noses with two openings each, four whole gills and free pseudobranchia .

Reproduction

Towards autumn, the swarms (often hundreds of animals beforehand) gradually dissolve. After an advertising ritual by the males, each female makes a choice for herself and pairs are formed. The males then become aggressive towards possible competitors and drive them away. Mating usually takes place from October to December (also several times) by pressing the slightly protruding genital openings together for seconds, whereby the thickened hard rays of the anal fin of the male improve adhesion. The young are released after about five to six months next spring (February, March in the south, May to July in the north). They are then approx. 38 mm long and largely identical to their parents. They were fed via the mother's vascular system (pseudoplacenta in the ovary). The eggs themselves are very small and poor in yolk.

Sexual maturity occurs in almost all males and in 60% of females within a year. Cases of sexually mature newborn males are known. In the first year of life, the mother animals are still small (around 10–12 cm) and only have three to five young. Later this number increases to an average of 10–12 boys. The largest females, up to 30 cm long and weighing around 1 kg, but very rarely, can carry up to 24 embryos. These are then tightly arranged in the mother's body. The body cavity is then still extended on both sides of the hemal thorns of the caudal vertebrae. Such females are then seven or eight years old, which is the maximum life span that Hyperprosopon argenteum can achieve. Young females are initially only slightly larger than males of the same age, but from the age of three you can notice more significant differences in size.

Danger

Thanks to the comparatively low mortality rate among juveniles, the one to three year old juveniles are the most common and have the most offspring, although individually they can carry fewer juveniles than older, larger females. The older fish are increasingly falling prey to predators (sea lions, otters, birds such as the cormorant, and predatory fish such as tuna and perch). From the middle of the 20th century, a noticeable decrease in stocks was observed. In addition to sport fishing, which is very important in California and can be successfully operated from jetties and jetties, commercial fishing by the Chinese has also started in California. The catch has now been partially regulated in terms of time, quantity and size, but many specimens of this species are still lost as by-catches and through poaching. Nevertheless, due to these protective measures, a recovery of the populations of the species Hyperprosopon argenteum compared to the 1990s could be determined in the years 2007 to 2009 . As coastal fish that penetrate into the estuaries , the populations at least in parts of the distribution area are influenced by the development of industry and settlement and the associated wastewater volume.

History of taxonomy

William P. Gibbons described Hyperprosopon argenteum in May 1854 in a lecture given to the California Academy of Natural Sciences . He established the new genus Hyperprosopon for this species . In this lecture he also described Hyperprosopon ellipticus , which at that time, however, he placed in the genus Cymatogaster . That same year the descriptions were also published in the Proceedings of the Academy of Natural Sciences of Philadelphia . Hyperprosopon literally means “over face”, and since “face” in Greek as well as in German can specifically mean the sense of sight, the reference to the “oversized eyes” can be easily established. Tarp gives a simpler explanation: the face is pointed 'upwards'. The specific epithet argenteum means silver. The English trivial name Silver Surfperch does not refer to this species, but to the related Hyperprosopon ellipticus . Hyperprosopon argenteum , on the other hand, is called Walleye Surfperch in English . Alfred Brehm called the fish the silver double hole . The designation double hole is a translation of the generic name Ditrema , which was introduced in 1862 by A. Günther for Hyperprosopon argenteum and some relatives. Brehm took many scientific names and descriptions of fish from Günther. Today this German name for Hyperprosopon argenteum is no longer in use.

literature

  • William P. Gibbons: Description of four new species of viviparous fish, read before the California Academy of Natural Sciences, Monday evening, May 15, 1854. Daily Placer Times and Transcript, Wednesday, May 18, 1854, page 2, column 3 [ newspaper]. Also published later as: Description of four new species of viviparous fishes from Sacramento River, and the Bay of San Francisco . Proceedings of the Academy of Natural Sciences of Philadelphia, 7, pp. 105-106, 1854 (first description)

Individual evidence

  1. ↑ a b c d e f Roger Tory Peterson, Earl S. Herald, William N. Eschmeyer: A Field Guide to Pacific Coast Fishes: North America. , Houghton Mifflin Verlag, 1999, ISBN 978-0618002122 , p. 230.
  2. ↑ Hyperprosopon argenteum on Fishbase.org (accessed on February 19, 2011)
  3. ↑ a b Common Surfperches of California ( Memento of the original from June 20, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Comparison of different species  @1@ 2Template: Webachiv / IABot / www.dfg.ca.gov
  4. ^ Louis Agassiz: On extraordinary fishes from California, constituting a new family. American Journal of Scientific Arts, ser. 2, 16, separate, pp. 1-12, 1853
  5. ^ Frederick W. Munz: The Photosensitive Retinal Pigments of Fishes from relatively Turbid Coastal Waters. In: The Journal of General Physiology , 42, 2, pp. 445-459, 1958 doi : 10.1085 / jgp.42.2.445
  6. ^ A b Fred Harald Tarp: A Revision of the Family Embiotocidae (The Surfperches). California Department of Fish and Game, Fish Bulletin 88, 1952 ( online )
  7. ^ ED Lane, W. Wulff, A. McDiarmid, DE Hay, B. Rusch: A review of the biology and fishery of the Embiotocids of British Columbia. P. 49. ( Online ; PDF; 1.2 MB)
  8. ↑ HW Frey: California's living marine resources and their utilization. Calif. Fish Game, Sacramento 1971
  9. ^ A b Robert D. Anderson and Charles F. Bryan: Age and Growth of Three Surfperches (Embiotocidae) from Humboldt Bay. California Transactions of the American Fisheries Society, 99, pp. 475-482, 1970 doi : 10.1577 / 1548-8659 (1970) 99 <475: AAGOTS> 2.0.CO; 2
  10. ^ John R. Moring, Feeding of Underyearling Walleye Surfperch, Hyperprosopon argenteum, in a Northern California Bay. Estuaries, 7, 1, 1984, p. 103. ( doi: 10.2307 / 1351961 )
  11. ^ Edward E. DeMartini: A correlative study of the ecology and comparative feeding mechanism morphology of the Embiotocidae (surf-fishes) as evidence of the family's adaptive radiation into available ecological niches. Wasmann J. Biol., 27, pp. 177-247, 1969
  12. ↑ a b Michael H. Horn: Intertidal Fishes: Life in Two Worlds. Academic Press, 1998, ISBN 978-0123560407 , p. 168.
  13. ↑ John Keast Lord: Ditrema argenteum . In: The naturalist in Vancouver Island and British Columbia. Vol. 1, pp. 106–120, 1866 ( full text at google books )
  14. ↑ North-Central Management Area: San Francisco Bay District Current California Ocean Recreational Fishing Regulations, Department of Fish and Game, California, Update December 1, 2010
  15. ↑ Surf Fish Population Study ( Memento of the original from November 12, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Department of Fish and Game, California  @1@ 2Template: Webachiv / IABot / www.dfg.ca.gov
  16. ^ Alfred Edmund Brehm : Brehms animal life. General customer of the animal kingdom. Volume 8. Third edition, Bibliographisches Institut, Leipzig and Vienna 1892, pp. 204–205
  17. ^ Albert Carl Ludwig Gotthilf Günther : Catalog of the Acanthopterygian fishes in the collection of the British Museum, Vol. 4, London 1862, p. 245

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