| Summary: | To investigate the age composition, growth pattern, mortality, and exploitation rate of <i>Triplophysa scleroptera</i> in the upper reaches of the Yellow River, we measured the total length (<i>L</i>) and body weight (<i>W</i>) of 347 individuals based on three sampling surveys from 2022 to 2023. The otoliths were used in this investigation to determine age. The total length of the collected samples ranged from 5.69 cm to 18.40 cm, body weight ranged from 1.65 g to 50.22 g, and the age ranged from 1 to 7 years old. The relationship of total length and body weight was <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>W</mi><mrow><mo>=</mo><mn>0.009</mn></mrow><msup><mrow><mi>L</mi></mrow><mrow><mn>2.942</mn></mrow></msup></mrow></semantics></math></inline-formula> for the total samples, and the growth pattern observed in the study belongs to the isometric type. The von Bertalanffy growth equation revealed that the fish had an asymptotic total length <i>L</i><sub>∞</sub> of 37.536 cm, and the growth coefficient <i>K</i> was 0.064 yr<sup>−1</sup>. Total instantaneous mortality rate (<i>Z</i>) of total samples calculated by the age-based catch curve method was 1.092 yr<sup>−1</sup>. The average instantaneous rate of the natural mortality (<i>M</i>), estimated by three different methods, for the total samples was 0.237 yr<sup>−1</sup>. The instantaneous rate of fishing mortality (<i>F</i>) for the total samples was calculated as 0.855 yr<sup>−1</sup>, and the exploitation rate (<i>E</i>) was determined as 0.783. As a whole, compared with other <i>Triplophysa</i> fishes, the growth rate of <i>T. scleroptera</i> in the upper reaches of the Yellow River is relatively slow, and the population of <i>T. scleroptera</i> has been overexploited. It is crucial to establish some effective management strategies to protect this species.
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