Environmental effects on the recruitment dynamics of coregonids from the Petchora River

Stock-recruitment processes in four coregonid species, Coregonus lavaretus pidschian, C. peled, C. albula maris-albi and C. autumnalis, from the Petchora River were investigated. The dynamics of density-independent mortality for the 0-group of each species were reconstructed using stock-recruitment models and compared with environmental factors including average monthly water surface temperature, average monthly water level, monthly total length of open sunshine, ice thickness during winter months, and date of steady ice cover setting. The results of a stepwise variable selection analysis showed that 68.7% to 95.1% of the recruitment variability is due to perturbations in environmental conditions. The primary factor influencing pre-recruitment mortality is insolation. Less important, but still significant, factors are water temperature and water level.