Individual fecundity study of Leuciscus idus in the Irtysh River of Xinjiang
To restore the resources of the natural group of Leuciscus idus in the Irtysh River Basin of Xinjiang, 117 L.idus were collected in the Burqin section of the Irtysh River in Xinjiang in May 2020, including 53 female stage Ⅳ samples, which can be used for individual fecundity related studies. The results showed that the breeding population was composed of 3+-7+ years old, and the individual absolute fecundity of individuals was 28390-97184 grains, with an average of (46955±14102) grains. The relative fecundity of standard length was (97-253) grains·cm-1, and the average was (145±32) grains·cm-1; the relative fecundity of body mass was (70-131) grains·g-1, and the average was (85±11)grains·g-1; from multivariate regression analysis, it could be concluded that ovarian mass was positively correlated with individual absolute fertility and relative fertility of standard length, and the partial correlation coefficient between ovarian weight and individual fertility was higher than of eviscerated body weight, age and gonadosomatic index. From the best-fitting equation, it could be seen that the fit degree of individual abso-lute fecundity and an ovarian mass was the highest (R2=0.916), and the relationship was F=1.074 m02+153.347 m0+ 19611.041. Therefore, the fitting equation of ovarian mass and individual absolute fecundity can predict the repro-ductive capacity of the natural population of L.idus in the Irtysh River Basin, thereby enriching its reproductive bi-ology data and providing a scientific basis for resource conservation and artificial breeding of L.idus.