Reproductive Biology and Efficiency of Natural Reproduction of Pikeperch Sander lucioperca in the Northeastern Part of their Distribution Range at the Kama Reservoir (Perm Krai, Russia)

Pikeperch Sander lucioperca is a valuable fish species whose reproductive biology and efficiency of natural reproduction, as well as the factors determining them, are poorly studied. Based on the materials collected in 2018–2023, the results of the study of sexual maturation, gonadosomatic index (GSI), absolute (AF) and relative fecundity (RF) of pikeperch from five areas of the Kama reservoir, located on the northeastern border of the natural range of the species, are presented. Population fecundity of pikeperch and efficiency of species natural reproduction based on egg to adult survival coefficients were estimated. Latitudinal variability of pikeperch sexual maturity rates within the reservoir was revealed. A decrease in generative metabolism relative to somatic metabolism was found with the age of fish after they reached the length of 55–60 cm and 11+ age, which is manifested by stabilization of the values of RF and GSI in larger and older fish. The maximum values of GSI, AF and RF were observed for pikeperch in the lower part of the Kama reservoir, which may be related to more favorable feeding conditions for the species. The lowest values of AF and RF were characteristic for the headwaters of the Kama reservoir with highest water flow. At the same time, pikeperch in the upper part of the reservoir were characterized by the highest survival rate from eggs to adult individuals. The lowest efficiency of natural reproduction was found in the central part of the reservoir, characterized by maximum width, presence of large bays and predominant distribution of shallow water habitats.