Length-Based Assessment of Hovsgol Grayling (Thymallus nigrescens), Lenok (Brachymystax lenok), and Burbot (Lota lota) Population Status in Lake Hovsgol, Mongolia Монголын Хөвсгөл нуурын Хөвсгөл хадран (Thymallus nigrescens), шөвгөр хоншоорт зэвэг (Brachymystax lenok), гутаарь (Lota lota) загасны уртад суурилсан популяцийн төлөв байдал

Abstract

Despite the global importance of inland fisheries, data available for stock assessment is often limited. Data-limited methods that use length composition data offer a potential approach to assessing more inland fisheries. We assessed the population status of three fish species in Lake Hovsgol, Mongolia through length-based spawning potential ratio (LBSPR) analysis and evaluation of trends in eight length-based indicators of population status, catch-per-unit-effort (CPUE), and body size. Hovsgol grayling (Thymallus nigrescens) were not yet overfished, but CPUE and body size declined due to targeting of large, mature fish. Lenok (Brachymystax lenok) were experiencing overfishing, especially of small, immature fish, which contributed to size–structure truncation. The burbot (Lota lota) population was healthy according to most indicators, but the lack of local life history information exacerbated already large uncertainties. Continued monitoring and improved coordination among fishers, managers, and scientists will be critical to enhancing the sustainability of these fisheries.