The Balkhash perch (''Perca schrenkii'') is a species of
perch
Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Percif ...
endemic to the
Lake Balkhash
Lake Balkhash ( kk, Балқаш көлі, ''Balqaş kóli'', ; russian: озеро Балхаш, ozero Balkhash) is a lake in southeastern Kazakhstan, one of the largest lakes in Asia and the 15th largest in the world. It is located in the ea ...
and
Lake Alakol
Alakol Lake ( kk, Алакөл, , from Turkic "motley lake") is a lake located in the Balkhash-Alakol Basin, part of the Almaty and Shyghyz regions, east central Kazakhstan. Its elevation is above sea level.
The lake is the northwest extensio ...
watershed system, which lies mainly in
Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
. It is similar to the other two species of
perch
Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Percif ...
, and grows to a comparable size, but has a slimmer build and is lighter in colour.
It has suffered a population decline which is blamed on introduced bream and predatory fish such as the
Volga pikeperch
The Volga pikeperch, or Volga zander (''Sander volgensis''), is a species of fish in the perch family Percidae. It is found in Austria, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Croatia, Hungary, Moldova, Romania, Russia, Serbia, Slovakia, and ...
.
Discovery and first scientific description
An expedition of
Alexander von Schrenk
Alexander Gustav von Schrenk (4 February 1816 – 25 June 1876) was a Russian naturalist born near Tula in what was then the Russian Empire. He was a brother to zoologist Leopold von Schrenck (1826–1894).
From 1834 to 1837, he studied science ...
to eastern
Turkestan
Turkestan, also spelled Turkistan ( fa, ترکستان, Torkestân, lit=Land of the Turks), is a historical region in Central Asia corresponding to the regions of Transoxiana and Xinjiang.
Overview
Known as Turan to the Persians, western Turke ...
collected this species in 1842, and deposited preserved specimens at the Imperial Academy of Sciences in St. Petersburg;
Karl Kessler
Karl Fedorovich Kessler (19 November 1815 – 3 March 1881) was a German-Russian zoologist and author of zoological taxa signed ''Kessler'', who was mostly active in Kyiv, Ukraine. He conducted most of his studies of birds in Ukrainian region ...
's formal description was published much later, in 1874, after the rediscovered specimens were sent to him by
Alexander Strauch
Alexander Strauch (1 March 1832, in Saint Petersburg – 14 August 1893, in Wiesbaden, Germany) was a Russian naturalist, most notably a herpetologist.
In 1861 he started working as a curator of the zoological museum at the Imperial Academy of Sci ...
.
[ The description was included in an article on fishes collected by the later expedition to Turkestan of ]Alexei Pavlovich Fedchenko
Alexei Pavlovich Fedchenko (russian: Алексей Павлович Федченко;
31 August/15 September 1873), a.k.a. Alexei Pavlovich Fedtschenko, was a Russian naturalist and explorer well known for his travels in central Asia. Alterna ...
.[Mamilov p. 71]
The fish is named in honor of Alexander von Schrenck (1816–1876) the Baltic-German Russian naturalist and collector/explorer of Central Asia and northern Russia. Von Schrenck published observations about this species in 1840.
Characteristics
The Balkhash perch resembles its congeners, the European perch
The European perch (''Perca fluviatilis''), also known as the common perch, redfin perch, big-scaled redfin, English perch, Euro perch, Eurasian perch, Eurasian river perch, Hatch, poor man’s rockfish or in Anglophone parts of Europe, simply th ...
(''Perca fluviatilis'') and the yellow perch
The yellow perch (''Perca flavescens''), commonly referred to as perch, striped perch, American perch, American river perch or preacher is a freshwater perciform fish native to much of North America. The yellow perch was described in 1814 by Samu ...
(''Perca flavescens''), in its general profile and its modest size,[ reaching a maximum total length of 50 cm and weight of 1.5 kg.] Like them it has spines on the tips of the opercula and in the dorsal, pelvic and anal fins, as well as sharing a similar dentition. It also shares with them the ctenoid scales that lend a rough texture to the fish when handled.[Mamilov p. 49]
It differs in its longer, thinner build and lower first dorsal fin;[ and whilst its congeners have marked vertical dark bars on their bodies, the Balkash perch normally lacks such markings when it attains its larger sizes, and is of a much paler hue. When vertical bars are present they are usually much less visible than in the other ''Perca'' species. There are, however, populations in which such bars are visible, along with coloured fins reminiscent of the other ''Perca'' species.][Mamilov p. 50] The body is covered with larger scales than those of its congeners, with 44–54 on the lateral line.[
It is a markedly variable species, occurring in ]ecomorph Ecomorphology or ecological morphology is the study of the relationship between the ecological role of an individual and its morphological adaptations. The term "morphological" here is in the anatomical context. Both the morphology and ecology ex ...
ic forms that have been termed 'pelagic', 'shoreline', 'riverine' and 'dwarfish'.[Mamilov p. 51] In other locations forms that grow at different speeds have been distinguished, or in another case 'lake' and 'reed' forms that differed in colour and body shape. Local extirpation has made it impossible to further verify these data.[
Individually variable features of the morphology include the presence or absence of a black spot on the first dorsal fin, and the presence or absence of scales on the opercula, as well as the position and number of mucus glands on the head.][Mamilov p. 55]
Distribution
FishBase
FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web. reports only that the Balkhash perch is found in Lake Balkhash
Lake Balkhash ( kk, Балқаш көлі, ''Balqaş kóli'', ; russian: озеро Балхаш, ozero Balkhash) is a lake in southeastern Kazakhstan, one of the largest lakes in Asia and the 15th largest in the world. It is located in the ea ...
and Lake Alakol
Alakol Lake ( kk, Алакөл, , from Turkic "motley lake") is a lake located in the Balkhash-Alakol Basin, part of the Almaty and Shyghyz regions, east central Kazakhstan. Its elevation is above sea level.
The lake is the northwest extensio ...
,[ both in ]Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
. N. S. Mamilov, a zoologist working in Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
, has described it as endemic to "the Balkhash lake watershed, including the Alakol Lakes system",[Mamilov p. 47] and has mapped the presence and absence of the species in various rivers and other water bodies in that area.[Mamilov p. 48] Maurice Kottelat
Maurice Kottelat (born 16 July 1957 in Delémont, Switzerland[C ...](_blank)
, in his 1996 IUCN assessment states that the species' range also extends into parts of this catchment area that are in China, though no data on such populations were available.
The Balkhash perch was introduced into the Nura and the Chu rivers, but in neither case was this a success.[
]
Fisheries
Historically the Balkhash perch was a food fish that provided economically important, and sometimes dominant, fisheries. It constituted one third of the volume of the commercial catch in Lake Balkash, and two thirds in the Alakol Lakes system, in the 1930s and 1940s.
Conservation status
In assessments from 1986 to 1994, the IUCN Redlist status of the Balkhash perch was already assessed as 'rare'. The 1996 assessment noted that the population had declined and noted that this decline was blamed on the introduction of bream
Bream ( ) are species of freshwater and marine fish belonging to a variety of genera including '' Abramis'' (e.g., ''A. brama'', the common bream), '' Acanthopagrus'', ''Argyrops'', '' Blicca'', '' Brama'', '' Chilotilapia'', ''Etelis'', '' L ...
and predatory species, such as the Volga pikeperch
The Volga pikeperch, or Volga zander (''Sander volgensis''), is a species of fish in the perch family Percidae. It is found in Austria, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Croatia, Hungary, Moldova, Romania, Russia, Serbia, Slovakia, and ...
(''Sander volgensis''). The population trend was described as 'unknown' and the overall assessment was that the species was data deficient
A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...
.
Mamilov wrote in 2015 that "Although the external morphology and life strategy of the Balkash perch appear rather adaptable, the species' future is uncertain."[
]
References
Sources
* Mamilov, N.S., Biology of Balkhash Perch (''Perca schrenkii'' Kessler, 1874). Chapter 3 in
{{Taxonbar, from=Q729804
Perch
Fish of Central Asia
Freshwater fish of China
Taxa named by Karl Kessler
Fish described in 1874
Lake fish of Asia
Lake Balkhash