An investigation on systematic history and distribution areas of tarek ( Alburnus tarichi (Güldenstädt, 1814))

This study aimed to determine the distribution area of tarek ( Alburnus tarichi (Güldenstädt, 1814)) and to define how it must be called according to the scientific name by evaluating its previous studies made by various systematisers and their reports on its distribution, and by comparing literature knowledge. The taxonomic characteristics of the collected samples were evaluated and several measurements and counts were taken on the samples; analfin origin 0-4 scales behind dorsal fin-base; 72-91 lateral line scales; 21-29 gill rakers; 7½-10 branched dorsal-fin rays and 10-12½ branched anal-fin rays. Body and caudal peduncle was moderately compressed. Body was covered by overlapping scales. Tarek has five different populations in the Basin. They are Van, Erçek, Nazik and Aygır Lakes and Koçköprü Dam Lake populations. The main living area of the tarek population is Lake Van; however, between May and June, mature individuals of tarek enter to tributaries of Van Lake. Some of them are Karasu, Bendimahi, Deliçay, Zilan, Karmuç, Sapur, Yanıkçay, Gevaş, Engil, Kurubaş and Akköprü Streams. At the end of study, it was concluded that tarek should be called as Alburnus tarichi (Güldenstädt, 1814) and it is an endemic fish species distributed only in Van Lake Basin.


Introduction
First systematic classification of tarek was at the study of Pallas, Zoographia Rosso Asiatica first published in 1814 (Pallas, 1814). In subsequent years, its taxonomic characters were examined by Gunther, Deyrolle, Sauvage, Battalgil, Kosswig-Battalgil, Ladiges and Kuru (Geldiay and Balik, 2009). The name of the species remains valid as tarichi as in the first literature. Cetinkaya (1999) reported that this naming was an Arabic originated word associated with "history" for Lake Van in Futuh-ul Buldan (El Belazuri, 1987). Although this word means "salted and stored small fish" in Arabic, it may be derived from Greek word "tarichos" referring salted fish or processed salted fish (Cetinkaya, 2000).
The initial distribution area of tarek was given as Gökçe Lake (Sevan) by Pallas (1814), however subsequent studies, only Van Lake has been reported as distribution area. Kuru (1975) recorded Başkale (Çığlı) Stream, the tributary of the Tigris River as the distribution area beside Van Lake Basin.
Evaluation of living organism in the ecosystem is primarily important for the protection of nature (Periotto and Tundisi, 2017). Maximum length values of tarek vary significantly depending on its habitat. Elp et al. (2014) reported that the biggest individuals have been lived in Erçek Lake introduced from Van Lake. The maximum fork length caught from Erçek Lake was 35 cm. However, Van Lake and surrounding streams flowing to the lake constitute the basic distribution area of tarek. The largest individual caught from Van Lake was recorded as 22.5 cm fork length (Elp and Cetinkaya, 2006). In Nazik Lake and Koçköprü Dam Lake, maximum fork length of tarek does not exceed 20 cm (Kocabas, 1999;Elp, 2002).
Aquatic organisms unpredictably resistant to hydrological variations (Figueiredo et al., 2019). Tarek is an anadromous fish. While it migrates from the salty-alkaline waters of Van and Erçek Lakes to freshwater streams for reproduction, but it is showed in shallow waters of Nazik Lake, a freshwater source (Kocabas, 1999;Ekici and Duyar, 2005). In Koçköprü Dam Lake, they migrate from dam lake to the tributary (from a freshwater to other freshwater) (Elp, 2002). Tarek has different five populations in the Basin; they are Van, Erçek, Nazik, Aygır Lakes and Koçköprü Dam Lake (Sen et al., 1999(Sen et al., , 2014Elp and Sen, 2006;Elp et al., 2014Elp et al., , 2016.

Study area and sampling
The study area consisted of the Van Lake Basin and Başkale (Çığlı) Stream, a tributary of the Tigris River, where the tarek has been reported by Kuru (1975). Some samples were collection materials which were used at the Elp et al. (2013). In addition, other samples were collected from Başkale Stream and Van Lake Basin with the permission of the local ethic committee (approval date: 25.06.2015 and decision number: 2015/08). Electroshock method was used to reduce the selectivity to minimum in sampling.

Measurements and counts
Study material consists of Alburnus tarichi. In order to determine distribution area of tarek, the samplings were done in Van Lake and Başkale Stream Basins. The taxonomic characteristics of the collected samples were evaluated and several measurements and counts were taken on the samples at laboratories of the Fisheries Faculty, Van Yuzuncu Yil University, Turkey.
Measurements and counts were taken according to Kottelat and Freyhof (2007). Standard length was measured as the distance measured from the nose tip to the end of hypural complex. Caudal peduncle was measured as the distance from the end of the anal fin to the end of the hypural complex. The number of the scales on the lateral line was counted from the first perforated scale on the upper edge of operculum to the scale on the end of the hypural complex, and those on the tail fin are expressed as "+". Gill rakers were counted through the first gill arch. When the last two branched rays at dorsal and anal fins connected to a single pterygiophore it was recorded as "1½". The origin of anal fin was determined based on the location of the first anal fin rays and how many scales there were behind the dorsal fin base.

Description
Body and caudal peduncle was moderately compressed; Head profile was slightly concave; back was not humped behind head; mouth was slightly superior; lower jaw was slightly projecting beyond tip of upper jaw; pelvic fin origin in front of dorsal fin origin; caudal fin forked, lobes rounded; pelvic fins were not reached anus. Body was covered by overlapping scales. Lateral line was complete, reaching caudal fin base. Pharyngeal teeth are in two rows, 2.5-5.2 (Elp et al., 2013).

Colour
Body colour is metallic grey, back darker, ventral whitish.

Results
In the samplings of this and other studies, it was observed that tarek has been distributed only in Van Lake Basin. Tarek has five different populations in the Basin. They are Van, Erçek, Nazik and Aygır Lakes and Koçköprü Dam Lake populations (Figure 2). The main living area of the tarek population is Lake Van; however, between May and June, mature individuals of tarek enter to tributaries of Lake Van. Some of them are Karasu, Bendimahi, Deliçay, Zilan, Karmuç, Sapur, Yanıkçay, Gevaş, Engil, Kurubaş and Akköprü Streams (Figure 2). Van and Erçek Lakes, with different tarek populations, have alkaline and salty water, whereas Nazik and Aygır Lakes have completely Koçköprü Dam Lake was constructed on Zilan Stream (Erciş, Van, Turkey) in 1992, and population of tarek in Van Lake had separated from the other water sources. A new population of tarek has formed after the dam constructed. It has been observed that population of tarek in Koçköprü Dam Lake enters to the Zilan, Ilıca, Kömürcü and Kündük Streams between May and August (Elp et al., 2006).
Tarek has been introduced to Erçek Lake from population of Van Lake in 1980s and different population took place from the other water sources. Individuals of this population are larger than the others. Mature tareks of this population go in to Memedik Stream and other small water sources for reproduction between May and June (Elp and Sen, 2006).
Apart from these populations, no other population was found in other water sources in the Van Lake Basin, except during reproduction period.
The samplings were made in Başkale (Çığlı-Zapbaşı) Stream that located in Tigris River Basin in different periods with electroshock method because of to be reported by Kuru (1975), and there was no individuals of Alburnus genus.

Discussion
Alburnus is a genus of Cyprinidae family distributed in Europe and Asia Minor. The distinguishing characters of Alburnus tarichi are shown in a recent study as follows: total lateral line scales number 70-90, gill raker number 21-29, anal fin origin 3-4 scales behind the dorsal fin, anal fin branched rays number 10-11 ½, scattered black spots located on scales (Elp et al., 2013). Individuals carrying these characters have been recognized as tarek.
First systematic records relating tarek were in Zoographi Rosso Asiatica written as 3 volumes by Pallas between 1811-1814 and in this book, tarek was called as Cyprinus tarichi. In binominal nomenclature, it was defined as Alburnus tarichi (Pallas, 1811). However, information on tarek was located in Volume 3 published in 1814. Moreover, this information does not belong to Pallas. In that regard, the information was given at the beginning of that section and it was recorded that its definition was done by Güldenstädt (Pallas, 1814). Since its first description, tarek has been evaluated in different genera of Cyprinidae family (Geldiay and Balik, 2009). Referring to, only in recent systematic studies, it has been reported in the genus Alburnus (Elp et al., 2013(Elp et al., , 2014. Belong to this information; it should be named Alburnus tarichi (Güldenstädt, 1814) according to the binominal naming. After these reporting, Alburnus tarichi has been begun to use in some studies (Cicek et al., 2015;Kaptaner, 2015;Oğuz, 2015;Sen et al., 2015;Kaptaner et al., 2016;Arihan et al., 2017;Caf et al., 2018).
Information about the distribution of tarek has been also given by various researchers. The first information has located in Volume 3 of Zoographi Rosso Asiatica by Güldenstädt. It was indicated that the tarek distributed in Gökçe Lake (Sevan) (Pallas, 1814). However, there is no living species of the genus Alburnus at that lake. In addition, the presence of tarek is not mentioned in "study of fish and fisheries in Lake Sevan" (Savvaitova and Petr, 1999).
This wrong knowledge was noticed by Berg and it was noted that location information by place Güldenstädt was mistake (Berg, 1949) and he reported that samples of Güldenstädt belonged to Van Lake. In subsequent years, the tarek has also been reported from Lake Van Basin.
Tarek introduced to Burdur Lake (Turkey) in 1966 and Erçek Lake in 1989. Introducing to both lakes were successful, however it has been reported that economic production was not at the predicted level because of waste waters discharged into Burdur Lake. Today, there is no tarek in Burdur Lake (Aksiray, 1982;Balik and Ustaoglu, 2006;Sen et al., 2015). Kuru (1975) reported that Başkale (Çığlı) Stream, one of the upper branches of Tigris River Basin, was a distribution area of the tarek beside Van Lake Basin. In the samplings of the present study and other studies on Çığlı Stream (Sen et al., 2014;Sen and Kara, 2016), tarek could not be caught. Samples were taken twelve times at the villages Atlılar and Albayrak around the stream and its tributaries. In these samples, there were individuals belonging to the genus Capoeta, Barbus and Turchinemachilus, but there was not caught individual belonging to the genus Alburnus. During face to face interview, these issues were asked to Kuru, he said that there might be a labelling mistake in the recordings of Başkale Stream.