Age structure of juvenile Amur sturgeon Acipenser schrenckii and kaluga Huso dauricus in the Fuyuan reach of the Amur River, Northeast China

Abstract

Amur sturgeon Acipenser schrenckiii Brandt 1869 and kaluga Huso dauricus (Georgi 1775) are critically endangered species with populations showing significant decline from historical levels due to overexploitation, yet little is known about their population structure. Adults are not often captured in the Fuyuan reach of the Amur River, Heilongjiang Province, Northeast China, and the government prioritizes juvenile sturgeon management. This study was conducted to determine the age and length/weight relationships of juvenile Amur sturgeon and kaluga in the Fuyuan reach of the Amur River. We estimated age using pectoral fin spine sections obtained from 65 juvenile Amur sturgeon and 50 juvenile kaluga. We compared the age estimates from two readers, and found 100% between‐reader agreement in 67.7% of the Amur sturgeon and 64.0% of the kaluga. The majority of differences in estimated age were within 1 year. Length/weight relationships (LWR) were calculated, and the LWR of the Amur sturgeon and kaluga were W = 0.0025L3.106 (r2 = 0.966）and W = 0.0022L3.175 (r2 = 0.989), respectively. Our study provides the age structure and LWR in juveniles of two sturgeon species.

Seasonal variation in diet of juvenile Amur sturgeon Acipenser schrenckii in the lower reaches of the Songhua River, Northeast China

“…The standard weight of Amur sturgeon was estimated by the equation given by Li et al. (2019): Ws = 0.0025L 3.106 ( r 2 = .966). The Kruskal‐Wallis test and χ 2 test of independence were used to assess the differences in mean IF and percentage of empty stomachs relative to season development (Zar, 1984).…”