ESTIMATION OF ENVIRONMENTAL CAPACITY OF HUCHO BLEEKERI IN TAIBAI RIVER BASED ON ECOPATH MODEL

Hucho bleekeri, a distinctive and regionally distributed cold-water fish in China, attained the status of a national first-class protected animal in 2021. To explore the current population of Hucho bleekeri in the Taibai River Basin, we estimated the existing resources based on biological survey data from the Taibai River conducted across four seasons from 2017 to 2018, utilizing systematic sampling techniques and the river reach method. Employing EwE software, we constructed an Ecopath model to depict the historical habitat of Hucho bleekeri in the Taibai River basin. The results showed that the total amount of Hucho bleekeri in the Taibaihe River was 3814 fish, with a 95% confidence interval ranging from 3624 to 4005 fish. Within this, the adult fish resources amounted to 1286, with a 95% confidence interval from 1233 to 1339, and juvenile fish resources accounted for 2528, with a 95% confidence interval ranging from 2438 to 2619. The carrying capacity of historical habitat environment for Hucho bleekeri in the Taibai River basin was 1.87 t/km², supporting approximately 5127 dult fish and 3399 young fish per kilometer square, with an additional 1728 fish for tail areas. The total productivity of the ecosystem was 1748.91 t/ (km²·a), with total primary productivity at 1643.00 t/ (km²·a), constituting 93.94% of the total productivity. The aquatic ecosystem displayed a connectivity index (CI) of 0.429 and s system omnivore index (SOI) of 0.087, respectively. Zooplankton exhibited the highest ecological nutrient conversion efficiency at 0.84. Key species identified within the ecosystem included Hucho bleekeri, Brachymystax lenok tsinlingensis, small middle and lower strata fishes. and phytoplankton. In conclusion, the existing resources of Hucho bleekeri in their historical habitats in the Taibai River Basin fall below their environmental capacity. Therefore, it is recommended that to enhance investigations of spawning grounds and habitat protection to facilitate the recovery of Hucho bleekeri.