Growth and biological characteristics of pike perch Sander lucioperca (Linnaeus, 1758) in the Amur River

Linear and weight growth of pike perch in the Amur River estuary is considered using the data on age determined for 197 specimens. The growth is described by von Bertalanffy and Schmalhausen equations. Some biological parameters of pike perch as the maximum size, age of mass maturation, etc. are calculated using the age-differentiated coefficients of natural mortality. The growth and biological parameters of pike perch in the Amur estuary are compared with the same parameters of this species in the Amur River at Khabarovsk. Recently 3 ecological forms of pike perch are distinguished in the Amur basin: i) riverine ecotype self-redistributed from Lake Khanka, ii) lacustrine ecotype in the lower Amur River, and iii) highly productive semi-anadromous marime ecotype in the Amur estuary. The 3rd phase of pike perch acclimatization is observed now in the Amur estuary known as the «bloom» phase accompanied with prominent increasing of population abundance and individual growth rate acceleration. Pike perch prey in this area mainly on juveniles of non-anadromous and diadromous fish, or on pond smelt Hypomesus olidus during their concentration in the estuary in winter.

The distribution of the desalinated waters of the amur estuary in the okhotsk sea according to satellite observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.