Diversity and Distribution of Genera Schizothorax and Schizothorichthyes in River Swat, Pakistan

River Swat arises from glacial fed waters of Hindukush Mountains throughout the year, flowing across the Kalam Valley through a ravine with a high speed flow to Madyan, lower plain regions of Swat Valley and Chakdarafor about 160 km. At the far south of valley, at the second time this river flows in a ravine joining River Panjkora at Qalangi and at last near Charsadda it flows down to the River Kabul (Akhtar et al., 2014).

The study area was divided into twelve different sites (Madyan (Daamanai), Qandeel, Chikrai, Kala-Kot, Bagh-Derai, Drsuh-Khela, Khwaza-Khela, Sher-Palam, NengwalaI, Manglor, Fizagat and Hayatabad (Bypass Road) (Supplementary Fig. S1). Fish were collected by fishing rods, cast nets and hand nets. The pore/hole size of the cast net was managed to capture normal length fishes and to avoid any fry and fingerling catchments. Sample were first washed in flowing water, dried and then kept on a plain platform with hard card/paper as a background and preserved in 10% formalin (Cadrin and Friedland, 1999).

The following measurements were taken from each specimen along with a snap shot depicting most of the morphological character for verifying and retaking of the measurements wherever required: lateral line scales; total length; fork length; standard length; pre-dorsal length; post-dorsal length; dorsal length; body depth; peduncle depth; peduncle length; pectoral fin rays; dorsal fin rays; pelvic fin rays; anal fin rays; caudal fin rays; head length; snout length; eye diameter; barble length; mouth position.

Table I.- Morphometric measurements (Mean±SEM, cm) and meristic counts (Mean±SEM) of genus Schizothorax recorded from River Swat.

A total number of 28 fish specimens were collected from the river swat in spring season 2015. These fish species belongs to genus Schizothorax (Heckel) and Schizothoraichtys (Misra). Six species namely Schizothorax plagiostomus, Schizothoraicthyses ocinus, Schizothoraicthys Labiatus, Schizothorax richardsonii, Schizothorax sinuautus and Schizothoraicthys macropthalmus were identified from 12 different site of the River Swat. Schizothtorax plagiostomus was recorded the most abundant (46.82 %) species of River Swat followed by Schizothoraicthys esocinus (17.85 %), Schizothoraicthys labiatus (14.28 %), Schizothorax Richardsonii (10.92 %), Schizothorax sinuautus (7.14 %) and Schizothoraicthys macropthalmus (3.57 %). Schizothtorax plagiostomus was the only species which was distributed throughout the River Swat. However, Schizothorax Richardsonii is vulnerable according to IUCN red list, 2017. This is a valuable game fish and need immediate protection. Various studies have been conducted in River swat for the illustration of fish fauna. All of the studies have shown variation in number of capture and fish species (Ahmed and Mirza, 1963; Mirza, 2007; Saeed et al., 2013).

Table II.- Morphometric measurements (Mean±SEM, cm) and meristic counts (Mean±SEM) of genus Schizothoraicthys recorded from River Swat.

Morphometrics measurements and meristic counts of individual fish species are given in Tables I and II. Fishes are sensitive to environmental changes and quickly adapt themselves by changing necessary morphometrics and morphological characters can show differences in response to different environmental (climate. temperature) and biological (food abundance) factors (Allendorf and Phelps, 1988). In the present study, fish belong to genus Schizothorax were of large size compared to fish belong to genus Schizothoraichtys. In general fish have shown variation in morphological traits both within and between the two genera and are reported to be captured from different locations of the River Swat. It has been proved that fish are more susceptible to environmentally induced changes and show morphological variations in relation to different localities of capture (Wimberger, 1992; Brraich and Akhter, 2015). Variations in meristic counts are also dependant on the body size and they increase with the increase in body length (Koshy et al., 2008). In the present study, meristic counts of genus Schizothorax are more compare to genus Schizothoraichtys and confirm that meristic counts are directly related to body size. The lateral line scales count is highly correlated to the fish locality and climatic variations (Brraich and Akhter, 2015). The results of the present study are in confirmation to the study that highly abundant fish (Schizothtorax plagiostomus) have more lateral scales (145-152) compared to other fish of this genus and genus Schizothoraichtys. The fish having more lateral scales have better adaptability in changing localities within the river (Watanable, 1998). Generally this variety in morphology results from isolation of a population fragments within regional habitat conditions. An adequate level of isolation might develop in observable phenotypic and genetic variations within species of fish populations, as a root for separation and management of different populations (Turan, 2004). Such variations could arise because of various means such as; reproductive isolation within various populations of fishes might be driven by evolving to various breeding zones (Hourston, 1982) or through hydrographic characteristics that diminish or impede migration within territories (Iles and Sinclair, 1982). Failing to distinguish or to deal with complex populations in control groups has resulted into the spawning components erosion, leading to the diminishing or fading of genetic diversity, and other unexplored environmental conclusions (Begg et al., 1999).

River Swat has suffered from severe human intervention in the last few decades resulting in habitat loss, degradation and ultimately affecting aquatic fauna. During the present study, it was observed that illegal fishing techniques; electric currents and use of explosive materials have resulted in the decrease of many important fish species. Schizothorax richardsonii is game fish and vulnerable and needs immediate conservation measures. Also the River Swat inhabits endangered fish species like Schizothorax esocinus, Tor macrolepis and Cyprinus carpio and needs immediate conservation efforts.

There is supplementary material associated with this article. Access the material online at: https://dx.doi.org/10.17582/journal.pjz/20180904060941

The authors declare no conflict of interest.