Comparing the reproductive indices between and within different common carp (Cyprinus carpio) populations

This study aimed to compare reproductive indices of broodstocks between and within (control and selected treatments) four different populations common carp of Hungarian-originated (TATA), North Iran, China-originated (RAN), and South Iran (Khuzestan). Control and selected treatments in each population comprised the average of the broodstock population and those chosen deliberately from 30% above the population mean (apart from shooter fish with excessive growth and out of the normal range), respectively, to calculate the genetic progress. Male and female reproductive indices were checked respectively by evaluating sperm quality (spermatocrit, sperm density per milliliter, percentage of motile sperm, and motility duration) and measuring working and relative fecundity, ovum and hydrated egg diameter, fertilization rate, hatching rate, the larval survival rate, and larval size after hatching. The results showed that, despite the high fecundity in the South Iran population, it has the lowest egg diameter and larval survival rate (p<0.05). Although the China-originated (control and selected treatments) population had the lowest sperm volume, sperm density per milliliter, and percentage of spermatocrit among different populations, the selected-treatment had the highest motile sperm percentage and the motility duration, which resulted in the most elevated fertilization rate belonging to it (p<0.05). The highest survival rate 24 hours post-hatching was observed in China-originated (control and selected) and North Iran-control, and the lowest in TATA (control and selected), North Iran-selected, and South Iran populations (p<0.05). China-originated control population gained the highest larval survival rate 72 hours after hatching. Although it did not differ significantly with the North Iran (control and selected) and TATA-control (p>0.05) populations, it has meaningful difference with the South Iran, TATA-selected, and China-originated-selected (p<0.05). The larval size in TATA-selected, North Iran-control, and South Iran is significantly smaller than other populations (p<0.05). There is no considerable difference in larval length size of the North Iran population between the control and the selected treatments, but it is significantly more in control than selected treatments in the China-originated and TATA populations. This finding illustrated that the selective breeding of broodstocks did not affect the reproductive indices within populations and the larval survival rate in F1. However, it improved the larval size. China-originated and North Iran populations performed satisfactorily in male and female reproductive indices, respectively, and it is worth bringing into mind hybridization between the two populations in future studies.