Some biological parameters of chum salmon in the spawning runs to the Paratunka River (Avachinsky Bay, Kamchatka) are analyzed on the materials of ichthyological researches conducted in 2010-2015 (3699 specimens sampled), observations on filling of the spawning grounds, and fishery statistics. The age at return is defined using scale samples and the age structure of the spawning run both for wild and hatchery populations. The fish origin is determined by the scale circuli patterns in the zone representing the juvenile period, comparing the scale samples from natural spawning grounds and hatchery weir. Accuracy of this method is estimated in 82-99 %. Abundance of the spawners had the increasing tendency since 2009. Three runs with different age structure and size of the fish were observed in the lower river: in early summer, late summer, and fall. The elder wild chum ran to spawning while the body length, weight and fecundity were similar for both stocks. The hatchery stock had higher male : female ratio. Survival of the wild fish from egg to the return was estimated as 0.67 %, and of the hatchery fish as 0.28 %. Portion of the hatchery fish was 44-48 % at the Paratunka mouth and 25-35 % on the spawning grounds, whereas it was 70-83 % at the hatchery. The chum salmons’ straying to certain loci of the river basin is determined.