The Migratory Biology and Feeding Habits of Downstream-Migrating Juvenile Chum Salmon <i>Oncorhynchus keta</i> in the Amur River of Northeast China

Abstract

The size of chum salmon juveniles is crucial to their survival. In order to understand the population status and migration patterns of juvenile chum salmon in the waters of the Amur River in China, this study investigated the status of juvenile chum salmon resources and their basic biological characteristics in the Amur River and the Ussuri River in China. The results showed that the average catch per unit effort (CPUE) of chum salmon in river margins was 0.140 ind·10−3 m3 for the Amur River and 0.255 ind·10−3 m3 for the Ussuri River. Chum salmon migrate downstream, mainly in mid-May in the Amur River and in early May in the Ussuri River, and no fish was caught in the rivers after June. Most chum salmon migrated when the water was between 10 and 14 °C. The average FL (fork length) and BW (body weight) of the Amur River samples were 37.1 ± 2.9 mm and 0.42 ± 0.09 g, respectively, while the Ussuri River samples’ FL and BW were 34.9 ± 3.7 mm and 0.36 ± 0.08 g, respectively. The empty stomach rate of the samples was zero, and the prey category of the samples was composed of fish, aquatic insects, copepods, and cladocerans, of which Ephemeroptera had the largest percentage index of relative importance (IRI%), with a value of 58.45%. The size of the downstream-migrating juvenile chum salmon in this study is similar to the size of those in some other rivers, and the CPUE varies depending on the river conditions.

Keywords

• resource density
• CPUE
• stomach content
• downstream migration pattern