Balkhash perch

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Balkhash perch
Systematics
Perch relatives (Percomorphaceae)
Order : Perch-like (Perciformes)
Subordination : Percoidei
Family : Real perch (Percidae)
Genre : Perca
Type : Balkhash perch
Scientific name
Perca schrenkii
Kessler , 1874

The Balkhash perch , a scientific honor of the Livonian naturalist Alexander von Schrenk Perca schrenkii called bony fish , has on the southeast border of the distribution area of the Eurasian perch Perca fluviatilis in Kazakhstan , due to the relative isolation of the waters since the Tertiary developed as a separate species. The species was named after Lake Balkhash .

features

The Balkhash perch forms several different morphs , which live sympatric in the same waters, but in different biotopes . A pelagic and a coastal form as well as dwarf forms are known. The pelagic form used in the fishing industry is around 50 centimeters long and weighs up to 1.5 kilograms.

The Balkhash perch is slightly lower, slimmer than the river perch , yellowish, with about five dark saddle bands over the back, which usually contrast strongly against the background. As with all perches, the vomer and palatina are still toothed, the preoperculare is thorny ventrally and the gill cover (operculum) has a sharp point at the back.

There are 41 to 54 scales along the sidelines. The first dorsal fin has 12–13 spine rays, the second 2–3 spine rays and 12–13 soft rays, the anal fin has 2 spine rays and 7–9 soft rays.

Occurrence and endangerment

This Turkestan species is mainly known from Lake Balkhash and Lake Alaköl , which have quite different and fluctuating salinity . Due to the associated catchment areas, its distribution area extends as far as China . The Balkhash perch was introduced to Uzbekistan and Kyrgyzstan in the 1960s and 1970s . The species does not acquire any major economic importance, especially since larger predatory fish ( pikeperch , catfish ) have often been used in their home waters . Together with other native species, the Balkhash perch only makes up 10–17% of catches. Once of considerable commercial value, it is now in danger of survival.

Individual evidence

  1. ^ A b John F. Craig: Percid Fishes: Systematics, Ecology and Exploitation. Aiaa, 2000, ISBN 978-0632056163 , pp. 12, 18, 23.
  2. ↑ M. Kottelat, 1996: Perca schrenkii . In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. Retrieved December 15, 2010.
  3. ↑ Patrick E. O'Sullivan, Colin S. Reynolds: The Lakes Handbook: Lake restoration and rehabilitation. John Wiley & Sons, 2005, ISBN 978-0632047956 , p. 195.

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