Satellite-Driven Synthesis of Fish Production Dynamics and Carrying Capacity Mechanisms in a High-Altitude Lake...

Understanding how limited energy constrains fish populations in fragile high-altitude lakes is essential for sustainable fisheries management. This study developed a satellite-based framework that integrated MODIS-derived chlorophyll a data with a vertically generalised production model. This framework was used to map Fish Potential Production (FPP) and establish a novel Fish Carrying Capacity Index (FCCI) for the endemic naked carp (Gymnocypris przewalskii) in Qinghai Lake, China, from 2002 to 2024. Over the 23-year period, lake-wide fish production increased 50-fold (from 2592 to 127,500 t) alongside an upward trend in FPP driven by primary production. Seasonally, FPP per unit area peaked in summer (July-August: 30-50 g/m²) and declined in spring (May-June: 0-30 g/m²). Spatially, the highest values occurred near riverbank and tributary estuaries, whereas central waters remained low. The FCCI revealed significant heterogeneity; the northwestern regions experienced high food demand pressure (FCCI > 0.5), while the southeastern areas were underutilised (FCCI < 0.3). As the lake-wide FCCI never exceeded 0.6, the current level of primary productivity can support further strategic restocking, provided that releases are redirected to the southeast to relieve pressure on the northwest. This study demonstrates how remote sensing can be used to balance fish conservation and production goals in sensitive plateau ecosystems.