ESTIMATION OF POTENTIAL BAIT RESOURCES AND CARRYING CAPACITY OF JUVENILE CHINESE STURGEON (ACIPENSER SINENSIS) IN BAILONG ISLAND MARINE RANCH

Mariculture conservation is an important initiative to complement the life history of Chinese sturgeon (Acipenser sinensis) and implement land-sea relay conservation. In order to investigate the potential bait resources of Chinese sturgeon in offshore marine pastures and the ability of marine enclosures, we conducted an annual survey of the Bailong island marine ranch off the coast of Wenzhou, Zhejiang Province, and assessed the amount of benthic and lower-middle biological resources in the marine ranch. Through the analysis of the feeding and growth status of the Chinese sturgeon and the contents of the digestive tract, the types of food that the Chinese sturgeon can eat in the marine pasture were obtained and verified, and the maximum resource carrying capacity of the Chinese sturgeon was estimated. The results showed that a total of 47 species of prey organisms were collected from the Bailong island marine ranch, belonging to 5 phyla and 8 classes, including 38 species of benthic animals and 9 species of lower-middle organisms. According to historical literature data, all of them could be eaten by Chinese sturgeon; According to the analysis of the contents of the digestive tract, the stocked Chinese sturgeon was adapted to the marine ranch and feed on their own. It is verified that it has ingested a total of 16 species of prey organisms collected from 4 phyla and 5 classes. The food composition was arranged according to the relative importance index (IRI): Crustacea (mainly shrimp and crabs)>Gastropoda>Fish>Pleurobranchia>Polychaete, and the feeding preference was arranged according to the size of the feeding selection coefficient: Crustacea>Belly Foot class>Petalbranch class>Polychaete>Fish. The annual maximum sustainable yield of potential bait resources of Chinese sturgeon in Bailong island marine ranch is about 811.389 kg, which can be used for 69 Chinese sturgeon juveniles to grow to sexual maturity. The results of this study indicate that the offshore fenced marine ranch is a potential model for marine conservation of Chinese sturgeon. In the next step, it is necessary to further study how to improve the scale and effect of marine fence conservation under the mode of artificial supplementation of natural bait, so as to provide basic data for the formation of Chinese sturgeon land-sea relay conservation.