INDIVIDUAL BIOLOGY OF CHUM SALMON FROM SUIFEN RIVER

To study the individual biology of chum salmon, 447 samples were collected in Dongning section of the Suifen River from 2012 to 2017. The results showed that the age groups of samples were 1⁺—5⁺, of which 3⁺ and 2⁺ age are dominant for females and males respectively. The relationships between body weight and body length of male and female salmon were as follows: W=0.0082×L^3.0604; W=0.0076×L^3.0746, which were all belonged to the type of uniform growth. Von Bertalanffy growth function was used in simulating the fork length growth of chum salmon. The fork length growth equations of male and female chum salmon aged 3⁺ years were L_t,F=141.64×e^{–0.11·(t+1.55)} and L_t,M= 119.51×e^{–0.13·(t+1.45)}, respectively. The fork length growth rate of chum salmon was inversely proportional to the age of sexual maturity. The total fork length of 50% male and female individuals reaching sexual maturity (L₅₀) was estimated by logistic moderating function with 42.15 cm for male and 51.53 cm for female. ARSS analysis revealed a significant difference between male and female individuals for L₅₀. Results showed that the average of absolute fecundity (F) and relative fecundity (F_L and F_W) were 3412 eggs, 52.42 eggs/cm and 1.17 eggs/g respectively. The positive correlation between F and fork length, body weight, and gonad weight of female chum salmon was significant, while the significant positive correlation between GSI and fork length, body weight, F was found. The power exponential equation was used to simulate the relationships of F and fork length, body weight respectively, and the regression function as follow: F=0.0311×L^2.7745(R²=0.638); F=1.946×W^0.9374(R²=0.704). This study will provide basic information for the conservation of chum salmon.