A grouped ecological operation technique to accommodate the spawning needs of different fish species

<p indent="0mm">At present, ecological reservoir operations mainly focus on promoting the spawning of specific fish species, such as the “Four Major Chinese Carps”, often neglecting the needs of other fish species. A major challenge in advancing ecological regulation is accommodating the spawning requirements of a wider range of fish species within a limited regulation period. This paper proposes a grouped ecological regulation technique that considers the diverse spawning needs of various fish species. In the study area, indigenous fish were classified based on spawning time, spawning type, and water temperature requirements to establish an overall framework for ecological regulation. For each group, the spawning habitat suitability evaluation method was improved, and discharge and water level constraints were coordinated for fish species that lay adhesive demersal eggs and drifting eggs. This approach proposes a discharge process designed to maximize the spawning requirements of indigenous fish during the regulation period. This technique was applied to optimize the ecological regulation plan for the cascade reservoirs in the lower reaches of the Jinsha River. Critical water temperatures for ecological regulation were set at 13.5°C, 16°C, 20°C and 22°C. An optimization strategy for the timing of ecological regulation, based on spawning effectiveness evaluation, was proposed, forming an ecological regulation plan that addresses the diverse spawning demands of fish at different periods. Without increasing the total number and duration of ecological regulation, the four-group regulation approach can cover more than 90% of the spawning demand of indigenous fish.