Successful Ultrasonography-Assisted Artificial Reproduction of Critically Endangered Sichuan taimen (Hucho bleekeri)

Sichuan taimen (Hucho bleekeri), a critically endangered species, is listed as a first-class protected species in China. The natural population has been missing from most of its known distribution areas for many years but was rediscovered in the Taibai River in 2012, providing an important resource for the conservation stocking of the Sichuan taimen. In this study, 43 wild adult Sichuan taimen collected from the Taibai River were determined for gamete maturity for artificial reproduction using ultrasonography. The echogenicity of the gonads before and after hormonal induction was described to determine broodstock identification, injection dose of hormones, and spawning time. Four batches of artificial breeding were successfully achieved in 2013, 2014, and 2016. Broodstock (19 females and 16 males) spawned with average fertilization and hatching rates reaching 80.2% and 61.0%, respectively. This study demonstrates that ultrasonic imaging is a convenient and efficient method to track the state of gonads of mature Sichuan taimen during artificial reproduction, which will assist in broodstock cultivation, and further large-scale proliferation and effective resource restoration of the Sichuan taimen.