Genetic Parameter Estimation of Growth Traits and Their Implications for Selective Breeding in Small Yellow Croaker (Larimichthys Polyactis).

The small yellow croaker (Larimichthys polyactis) is an important mariculture fish species, which necessitates systematic genetic analysis of growth-related traits to accelerate precision breeding. To address this, 1051 individuals from 26 full-sib families were evaluated as part of this study to determine the genetic parameters of nine growth-related traits at 10 months of age: total length, body length, head length, body height, caudal peduncle length, caudal peduncle height, trunk length, tail length and body weight. Family-level inbreeding coefficients ranged from 0.125 to 0.438, indicating moderate to high genetic relatedness within families. Genetic parameters were estimated with a single-trait animal model in which the corresponding trait measured at 6-month of age fitted as a linear covariate and days of age was included as a fixed effect. Heritability estimates for individual traits were moderate (0.29-0.42). Positive genetic and phenotypic correlations between trait pairs were consistently, ranging from 0.55 to 0.99, and 0.49 to 0.98, respectively. Repeatability estimates for the traits tested ranged from 0.60 to 0.87. Under a 30% selection ratio, the predicted genetic gain and relative genetic gain for body weight in the next generation were 3.54 and 7.95%, respectively. These results provide a robust framework for the development of selective breeding programs in small yellow croaker, enabling targeted enhancement of growth performance in aquaculture operations.