The Fourth International Stock Enhancement & Searanching

Poster Abstract

11. THREATENED FISHES OF THE WORLD: SCHIZOTHORAX ZARUDNYI NIKOLSKII, 1897


Mahdi Ghanbari and Mansoureh Jami
Institute of Hamun International Wetland, Zabol University, Zabol, Iran. Tel: +98542-2236961-2, Fax: +98542-2226765
ghanbari.msc@gmail.com

Common name: (English name: Snow Trout, Persian name: Anjac, Hamun Mahi, Mahi Khaju, Shir Mahi & local name: white fish pronounced sefidak). Conservation status: Endangered (Ghanbari et al., 2009a, Zabihi, 2006). Identification: Body is cylindrical, dorsally blackish and lateral side is pale yellow incolour. Biometric details are: Depth 5.3-20.2% of SL, Dorsal spines(total): 4 - 4; Dorsal soft rays (total): 8; Anal spines: 2; Anal soft rays: 5. The breast is naked or sparsely scaled. There is a pelvic axillary process. The scale sheath around the anal papilla and anal fin extends about one third to half way between the anal fin origin and the pelvic fin base. Scales are very small, horizontally ovoid and have an almost central focus. Scales are obliquely inserted in the scale pockets on the mid-flank above the lateral line and below the dorsal fin. Scales on the nape are none to minimally imnbricate. Radii are found on all fields and are numerous. Gill rakers are long, reaching the third to the sixth adjacent raker when appressed. The interior margin of each raker is serrated. Pharyngeal teeth usually 2,3,5-5,3,2, spoon-shaped with a slightly hooked tip. Anterior teeth are more rounded and thicker. There are 2 pairs of barbels, the anterior ones long to rudimentary in literature sources. The barbels are subequal in length, the anterior ones not reaching the eye and the posterior ones not reaching beyond the eye. The mouth is usually slightly subterminal but can be terminal or have the lower jaw projecting slightly. The gut is elongate and coiled (Coad, 2002). The chromosome number is 2n=96, NF=142, comprising 9 pairs of metacentric, 14 pairs of submetacentric and 25 pairs of acrotelocentric chromosomes, and the fish is a tetraploid (Hosseini and Kalbasi, 2003; Kalbassi et al., 2008). Distribution: This fish is native of Sistan zone and its settlement was in Hamun Lake, but this lake became dry because of the drought in the field. Now, we can see this fish only in Chah-nimeh reservoirs (61°36'–61°43'N, 30°45'–30°50'E,) (Ghanbari et al., 2009b, Zabihi, 2006, Coad, 2002). Chahnimeh reservoirs occupy an area of 4.700 ha and 680 million cubic meter capacity. They are composed of three sub sectors 1(21 km2), 2(9 km2), and 3(17 km2) connected together by a system of channels. There is no continuous source of water supply into the reservoirs. The main source of water is Hirmand River which, unfortunally, is often dry. Abundance: The snow trout population size is poorly studied and there is no population stimate. Accounted for 60% of total harvest before the drough in the Hamun Wetland but now is rarely found (Ghanbari et al., 2009a). Habitat and ecology: Found in the open lake, in reed beds and in pools in Sistan. It is the only species in Sistan common in the open lake in winter. Young probably make their way up upstream in the flood season as only adults are found in the lake in winter. The species is extremely abundant in pools left in stream beds when the floods recede. Spawning may occur in rivers as fry have not been found in the lakes (Coad, 2002). Zabihi (2006) characterises it as a potamodromous species and notes that in March and April, if there is no flow in the rivers and thus no migration from the lake is possible, female gonads are reabsorbed. Reproduction: Mature specimens migrates during April- May from rivers and lakes to cold and well oxygenated waters (Streams and their tributaries) to breed in shallow pools within boulders, sand and gravel. The breeders after laying eggs migrate back to rivers and lakes leaving their young ones behind. The fertilized eggs are adhesive in nature and normally stick to sand, gravel or other substrate so that they are saved from being washed away by strong currents, floods etc. During the breeding season the species exhibit definite secondary sexual characters. Females are characterized by possessing soft, enlarged and distended belly whiles, while males develop prominent nuptial tubercles on the snout coupled with roughness of the body. The roughness of the body and the tubercles becomes evident just before spawning season and disappear shortly after the spawning. Males normally mature about a month earlier than females under almost identical ecological condition (Ghanbari et al., 2009a). Threats: Propagation of the said species in nature has been drastically effected. Recruitment is not to the level of maintaining its population. The fish catch has shown declined trend (Ghanbari et al., 2009a,b). Overfishing is a potential cause of population declines and a serious complicating factor for conservation. Conservation action: SHILAT, according to the Government sector priorities, is taking up a priority to save this species before it gets extinct from natural water bodies. Experimental trials on artificial breeding and rearing of the species have been conducted by several research institutes in Iran. Conservation recommendation: Some form of legal protection should be instituted, education of local people initiated, captive breeding undertaken. Research for population preservation and restoration is required. Natural habitats should be protected.

References
Coad B W (2002) Freshwater Fishes of Iran.  First posted 26 February 2002 at www.briancoad.com, maintained by Brian W. Coad and Nicholas P. Coad, Ottawa, Ontario, Canada. 2039 pp., 287 figures.
Ghanbari M, Jami M, Rahnama M (2009). Studying natural reproduction, spawning grounds and spawning period of Schizothorax zarudnyi population in Chahnimeh Reservoirs, Sistan Province, Iran. Iran J Fish Sci In press. In Farsi.
Ghanbari M, Jami M, Omrani M, Shah-Hosseini GH (2009). Studying some biological characteristics of Schzothorax zarudnyi (Cyprindae), an endemic fish and little-known in Iran. The First International Conference of Water Crisis. Zobol, Iran. 
Hosseinie SV, Kalbasi MR (2003) Karyological study on snow trout, Schizothorax zarudnyi, in Zahak of Sistan-Balochestan Province - Iran. Iran J Marine Sci 2(1):13-22. In Farsi.
Kalbassi MR, Hosseini SV, Tahergorabi R (2008) Karyotype analysis in Schizothroax zarudnyi from Hamoon Lake, Iran. Turk J Fish Aquat Sci 8(2):335-340.
Zabihi M (2006) Some aspects of reproductive biology of Schizothorax zarudnyi. Iranian Fisheries Research Organization, Agriculture Research and Education Organization, Ministry of Jihad-e-Agriculture, Zabol. http://en.ifro.ir (abstract).
Zabihy M, Pourkazemi M, Kazemi R, Kamalai A (2004) Determination spawning season and changes in reproductive cycle of Schizothorax zarudnyi and condition factor in Hamoon Lake. Iran J Fish Sci, 12(4):41-56. In Farsi.