Effects of environmental parameters on morphological traits of Squalius namak in the Jajrood River

Fish shape is influenced by variable environmental parameters and in morphological studies, the relationship between the morphological features and environmental parameters are barely investigated. Therefore, the present study aimed to investigate the body shape of Namak Whitefish (Squalius namak) being influenced from environmental factors of the Jajrood River and also evaluate the contribution of each factor in shape variation. 103 specimens were collected from the Jajrood River. The environmental factors, i.e. water velocity, depth, temperature, pH, oxygen, the diameter of substrate stones, EC and TDS were record in the sapling points. The specimens were photographed and 13 landmarks for the geometric morphometric methods using TPSDig2 and 17 distance features for traditional morphometrics were measured. The geometric morphometric data were analysed using the package Geomorph in R software. The relationship between distance features in the traditional morphometric and the environmental factors were examined using two-block partial square regression. That was a positive significant correlation between the variables of traditional morphometrics and the environmental factors. The diameter of stone had the greatest positive significant relationship with the morphological features including pre-dorsal and pre-pectoral lengths.  As to the geometric morphometrics, the greatest positive relationship was found between the depth and the landmarks 4, 9, 5 and 6. The present study indicated that there was polymorphism in Namak Whitefish because of environmental factors.