Aquatic biodiversity of the Yarlung Zangbo River is both unique and fragile, with its ecological environment currently under significant pressure. However, comprehensive studies on the biological characteristics and resource status of fish in its tributaries remain insufficient. In this study, we analyzed the population structure, growth characteristics, and resource dynamics of 2058 specimens of Schizopygopsis younghusbandi that were collected from four major tributaries in the middle reaches of the Yarlung Zangbo River (Duoxiong Zangbo, Lhasa River, Niyang River, and Nianchu River) between 2023 and 2024. Population parameters were estimated using the Von Bertalanffy growth equation, revealing asymptotic body lengths (L∞) between 387.877 and 414.535 mm and growth coefficients (k) ranging from 0.154 to 0.174. Notably, the k values exhibited a gradual decline in growth rate with increasing altitude. Based on calculations from FiSAT II software, the exploitation rate (E) revealed that the Duoxiong Zangbo population remained within a safe range (E < 0.5), whereas the Nianchu, Lhasa, and Niyang River populations were overexploited (E > 0.5), with their population structures showing signs of under-ageing and miniaturization. To ensure stable population continuity, the minimum catchable body lengths were estimated as 248 mm, 240 mm, 233 mm, and 236 mm for the Duoxiong Zangbo, Nianchu, Lhasa, and Niyang Rivers, respectively, with slight variations among tributaries. These findings suggest that S. younghusbandi populations in the Yarlung Zangbo River tributaries are adversely affected by external pressures and face a decline, necessitating effective conservation and restoration strategies.

Clarifying the genetic structure and population history of a species can reveal the impacts of historical climate and geological changes, providing critical insights for developing effective conservation strategies for ecologically significant fish. The Markakol grayling (Thymallus brevicephalus), an endangered species found in the Altai‐Sayan Mountain region of Central Asia, serves as an ideal model for studying these factors. In this study, populations of a grayling (Thymallus) species discovered in the upper Irtysh River headwaters in Xinjiang, China, were analyzed to assess genetic diversity and population structure. Mitochondrial DNA sequences (cytochrome b and control region), along with 10 microsatellite markers, were used to examine genetic variation. Phylogenetic and genetic distance analyses confirmed the species, long misidentified as Arctic grayling (T. arcticus), as T. brevicephalus. This species can be divided into two distinct geographic groups: eastern and western, with the Crane River acting as the boundary. The divergence between these groups likely corresponds to refugia formed during the Pleistocene glaciation of the Altai Mountains, approximately 0.48 MA (million years ago) (range: 0.30 to 0.71 Ma). High haplotype diversity (Hd > 0.5) and low nucleotide diversity (π < 0.005) suggest that, despite the species' genetic richness, T. brevicephalus remains vulnerable to genetic drift, which could threaten its long‐term survival. This vulnerability may stem from inbreeding within small refugial populations during the glacial period, followed by gradual population expansion. Our study offers novel insights into grayling populations, with results that have direct implications for management by serving as a tool for the identification of conservation units.

The Yarlung Zangbo River (With a total length of 2057 km, the river forms part of the Ganges–Brahmaputra River system), located in the core region of the Tibetan Plateau, hosts a unique yet fragile aquatic ecosystem. Fish populations inhabiting this ecosystem have been significantly impacted by external factors, leading to declining resources. This decline is particularly evident in local tributaries, including the DuoXiong Zangbo River—a main tributary where scientific research remains scarce due to its geographic remoteness. Consequently, the status of schizothoracinae in this river remains poorly understood, necessitating research on their population structure, growth characteristics, and resource dynamics, as well as the extent of external disturbances. During the 2023–2024 season, fishery surveys were conducted during two sampling periods: summer (June–July) and autumn (September–October). This study focuses on the Duoxiong Zangbo River, a tributary of the Yarlung Zangbo River, targeting three schizothoracinae fish species: Schizothorax o’connori, Oxygymnocypris stewartii, and Ptychobarbus dipogon. The results show that their body lengths ranged from 23.02 to 440.00 mm, 23.02 to 460.00 mm, and 45.18 to 418.00 mm, with body weights ranging from 0.30 to 1394.30 g, 0.20 to 1013.00 g, and 1.20 to 814.30 g. Age distributions spanned 0–14, 0–16, and 0–13 years, respectively, indicating a trend toward younger and smaller individuals. Von Bertalanffy growth modeling revealed asymptotic body lengths (L_∞) of 591.233 mm, 507.557 mm, and 515.292 mm, with growth coefficients (k) of 0.098, 0.122, and 0.118, respectively. These parameters suggest that the populations are exhibiting accelerated growth strategies in response to fishing pressure. Using FiSAT II, exploitation rates (E) were calculated as 0.547, 0.758, and 0.711 for the three species, with predicted maximum sustainable exploitation rates of 0.579, 0.882, and 0.884, respectively. These findings indicate that the three schizothoracinae species have approached the threshold of overexploitation and are facing threats of overexploitation. In summary, this study demonstrates that schizothoracinae in the DuoXiong Zangbo River are experiencing adverse effects from external pressures, with populations at risk of decline. These results underscore the urgent need for targeted conservation and management strategies.