Золотой окунь

Золотой окунь
Большой, укомплектованный женским золотым окунем, пойманной из -за обдумывания: приманка для рыбалки все еще во рту.
Статус сохранения
Наименьшее беспокойство ( МСКН 3.1 )
Научная классификация
Домен:	Эукариота
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Percichthyidae
Genus:	Macquaria
Species:	M. ambigua
Binomial name
Macquaria ambigua (J. Richardson, 1845)
Synonyms
Datnia ambigua J. Richardson, 1845 Plectroplites ambiguus (J. Richardson, 1845) Ctenolates macquariensis Günther, 1871 Dules auratus Castelnau, 1872 Dules flavescens Castelnau, 1875

Золотой окунь ( Macquaria Ambigua ) представляет собой вид среднего, желтого или золотого цвета австралийской пресноводной рыбы , который можно найти в основном в системе реки Мюррей-Дарлинг , хотя подвид обнаружен в системе озера Эйр - Купер-Крик и в другом подвиде. подозревается, что является наследственным для всех других популяций, находится в системе реки Фицрой в Квинсленде . Другими распространенными названиями для золотистого окуня являются « Goldens », « Yellowbelly » и « Callop », последние обычно используются только в Южной Австралии .

Золотой окунь - это не настоящий окунь , который принадлежит роду Perca от семейства Percidae , а член семейства Percichthyidae ( умеренного окуня ). Этот относительно широко распространенный и широко укомплектованный вид является важной рыболовной спортивной рыбой в Австралии.

Описание

Золотой окунь-это рыба среднего размера, обычно 30–40 см и 1–2 кг в реках. Рыба с рек меньше и несколько обтекания-рыба в искусственных задусках гораздо более глубоко тела и показывают гораздо большие средние и максимальные размеры. В реках было зарегистрировано до 9 кг, в результате 15 кг. 24-килограммовая рыба, пойманная на Коу Болоте, Виктория в начале 1900-х годов, и маркированная и продаваемая как «окунь Мюррея», часто называют самым большим зарегистрированным золотым окунем, но эта запись сомнительна-эта запись сильно превышает все остальные Записи размера для золотистого окуня, и рассматриваемый образец гораздо чаще был треской Murray ( Maccullochella peelii ), которые растут до гораздо больших размеров, чем золотые окунь

Golden perch have an elongated, deep but laterally compressed body, with a sizeable mouth, small to moderate-sized eyes, a distinct curve to the forehead, and a distinct "hump" above the head. The opercula or gill covers possess a small, flat spine sharp enough to cut unwary fishermen's fingers. The caudal fin, soft dorsal fin, and anal fin are rounded. The spiny dorsal fin is short to moderate in length and strong. Golden perch vary from in colour from pale silvery-gold (turbid waters) to deep yellow/gold or bronze-black (very clear waters).

A wild golden perch from an upland river: Note the much leaner, slimmer shape of wild specimens and the intense golden colouration.

Taxonomy

The genus name Macquaria derives from the Macquarie River, where the first species in the genus, the Macquarie perch (M. australasica), was collected. However, the genus name Macquaria was applied to golden perch much later. The naturalist Richardson actually named golden perch Datnia ambigua and applied the specific name ambigua (Latin for "doubtful") to the species because, as he states in his species description, he could not decide in which of two genera to place it, Dules (now Kuhlia species) or Datnia (now various Terapontidae species):

“I have had much doubt as to whether this fish should be placed in the genus Dules, or Datnia. It agrees with the group of Dules that has two opercular points, in the number of dorsal rays, and in the presence of palatine teeth, but in general habit it is more like Datnia, strongly resembling it in the strength of its dorsal and anal spines, and in the number of rays in the anal. The only two specimens [8.5 and 14 inches standard length] I had the opportunity of examining are dried, and are both mutilated in the caudal fin, so that I am unable to describe the form of that member, and can give no anatomical details.”

This choice of specific name was unwittingly appropriate. Golden perch are neither a khulid nor a terapontid, and Richardson also erroneously stated the golden perch's habitat was "Western Australia", when in fact the species is not found in that state. (This error was corrected, presumably by Richardson himself, in at least one reprint of the publication in question.)

Range

Golden perch are native primarily to lowland reaches of the Murray–Darling River system, but also extend far into slope habitats and occasionally even lower upland reaches. In the Murray–Darling system golden perch are often found in sympatry with Murray cod.

The Macquaria perches, of which golden perch are one, continue the trend present in Murray–Darling native fish genera of diversification into more generalist lowland species and more specialist upland species. Golden perch, M. ambigua, represent the lowland species, while the closely related Macquarie perch, M. australasica, is the more specialised upland species which used to inhabit the upland reaches of the southern Murray–Darling basin, although this endangered species has now been almost wholly displaced by introduced trout species, dams, and associated effects such as cold-water pollution, and habitat degradation/modification.

Like many Murray–Darling native fish, golden perch have crossed river catchments through natural river capture/connection events. Golden perch are found naturally in the Fitzroy–Dawson River in central Queensland and the internal Lake Eyre–Cooper Creek drainage system of Central Australia. The fish has also been successfully introduced to other river systems in the Northern Territory, Queensland, and New South Wales, confusing studies of the natural range. Introductions into Western Australia have been unsuccessful.

Both of these separate populations are at least subspecies, possibly separate species, due to isolation from Murray–Darling populations, genetic drift, and natural selection. The taxonomy of golden perch has not been updated to reflect this, although the term Macquaria ambigua oriens, denoting subspecies status, has recently appeared in literature discussing the Fitzroy–Dawson population. Some research indicates the Fitzroy River population is the ancestral golden perch population.

Reproduction and biology

In the Murray River, wild male golden perch generally reach sexual maturity at 3 years of age and 32.5 cm in length, and wild female golden perch at 4 years of age and 40 cm in length. The latter fact is a concern given that minimum size limits for the species are currently less than 40 cm, at 30 cm.

Originally, temperatures close to 24 °C were considered necessary for golden perch to spawn, but as with all Murray-Darling fish species, multiple field studies have shown that their "required" spawning temperature is flexible and that they can and do spawn at lower temperatures. In the Barmah Forests region of the Murray River, for instance, fertilised drifting golden perch eggs have been netted in water temperatures as low as 16.9 degrees Celsius (full range 16.9 to 24.7 degrees). Golden perch have a flexible breeding strategy but generally (but not always) require a spring or summer flood or "fresh" (temporary, within-channel increase in flow) to stimulate spawning. Like some other primarily lowland native fish species of the Murray–Darling river system, these floods or freshes appear to be necessary for good survival and recruitment of spawned fish. Very small freshes appear to be sufficient for some spawning and recruitment, however.

Golden perch are highly fecund; females between 2.2 and 2.4 kg produce about half a million eggs per spawning event, with fish above 2.5 kg producing well in excess of this number. The eggs are generally planktonic, and hatch fairly quickly (24 to 36 hours).

Like other Macquaria species, sexual dimorphism is present, with females reaching much larger maximum sizes than males. Females also reach sexual maturity at older ages and larger sizes than males.

Very long migrations are part of the golden perch's ecology, particularly preceding spawning. Adult fish have been recorded migrating well over 1,000 km when flood conditions allow passage over weirs and other man-made obstructions. Smaller migrations are important in the ecology and dispersal of juvenile fish. The evidence suggests that before European settlement, huge shoals of golden perch roamed the entire lowland and slope reaches of the vast Murray-Darling River system, unimpeded. Thus, the gradual loss of fish passage through the numerous dams, weirs, locks, and other barriers (estimated at 4,000 in the Murray-Darling system) now present has had severe impacts on the species. Some major weirs have been remediated to provide fish passage, however.

Golden perch have unusually broad temperature limits, from 4 to 37 °C, and unusually high salinity limits for a freshwater fish, up to 33 parts per thousand.

Golden perch continue the trend, among many native fish of southeast Australia, of being very long-lived. Longevity is a survival strategy in the often challenging Australian environment which ensures that most adults participate in at least one exceptional spawning and recruitment event. These events are often linked to unusually wet La Niña years and may only occur every one or two decades. Maximum recorded age is 26 years.

Diet

Adult golden perch are carnivores, feeding on smaller fish and macrocrustaceans, including yabbies, shrimp, frogs, small fish, and aquatic invertebrates.

Angling

Generally a very good angling species (though renowned for being "moody"), golden perch are fished throughout their range. Baits include small yabbies and shrimp, as well as various types of deeper-running lures. Recreational harvest of the species is suspected to be significant.

Conservation

Wild populations have declined significantly, and a number of populations lost in upper reaches of rivers, due to dams and weirs blocking migration, mitigating floods and freshes, regulating flows, and releasing unnaturally cold water ("thermal pollution"), all of which interfere with migration, spawning, and recruitment. They are listed under the Victorian Flora and Fauna Guarantee Act 1988 and classified as "Vulnerable" for management purposes. Golden perch are extremely migratory and migration appears to have been important in maintaining populations over the length of rivers, particularly the upper reaches.

Weirs are proving to be a more significant threat to golden perch than first thought, with a 2006 study showing that about 90% of golden perch larvae passing through undershot weirs are killed. The species is bred in hatcheries, though, in large numbers, and stocked. Concerns over genetic diversity issues are growing.

References

• Froese, Rainer; Pauly, Daniel (eds.). "Macquaria ambigua". FishBase. October 2005 version.
• King AJ, Tonkin Z and Mahoney J (2008). Environmental flow enhances native fish spawning

and recruitment in the Murray River, Australia. River Research and Applications. DOI: 10.1002/rra.1209

• Koehn, J. D. and Harrington, D. J. (2005). Collection and distribution of early life stages of the Murray cod (Maccullochella peelii peelii) in a regulated river. Australian Journal of Zoology 53: 137–144.
• Lake, J.S. (1967). Rearing experiments with five species of Australian freshwater fishes. I. Inducement to spawning. Australian Journal of Marine and Freshwater Research 18: 137–153.
• Lintermans M (2007). Fishes of the Murray-Darling Basin: An introductory guide. Murray-Darling Basin Commission, Canberra.
• "Macquaria ambigua". Integrated Taxonomic Information System. Retrieved 11 March 2006.
• Ричардсон, Джон. Ихтиология путешествия HMS Erebus & Terror, под командованием капитана сэра Джеймса Кларка Росса, RN, FRS London: M.Dccc.xliv - M.Dccc.xlviii [1844–1848]. Лонгман, Браун, Зеленый и Лонгманс.
• Rowland, SJ (1996). Разработка методов масштабного воспитания личинок австралийской пресноводной рыбы Golden Perch, Macquaria Ambigua (Richardson, 1845). Морские и пресноводные исследования 47: 233–242.

Внешние ссылки

• Недниковая рыба Австралия - страница золотистого окуня